ater ese ighasatelnty penne eee TT Se peste te a! eater! - Sie deserese eee ETO ee TE ao Soomsanrene reise 3 rie ate het we eR kaid x hie eet dsb tea iererayra teres een Sth ld Ad | —- ge Wwe ONG espe a ee ot ad Oe ed (hes ON tes er em 1d O nebo ne Sg a we ay Ne f i é ete | impaunetad et | . NAY ee TT pre UNG, Me * an peer DOS prem wt mL | wastes PNG ae | ahs 2 sc § Nr = vy” ie v vee - Ee yest ETTLT Naw AEC EET, ae As oe aes meer wil enn wet U ayy VSS be mA atte A Si tte heer Ter wibetslableh she » Vs gris > wh ; a Me | | aeowK “Ott VIC AIS 7 Whbhidettih paces «ety oh v x “ah 1) “a eas Wyynh avand be ay ee 'p ae aes re Coe oS ahaa dents Jail Shine ©. Viviiites an 7 wee oe. Bele seipepoayes : gee WN Za ANS ar PIES er ar ~ = NS AVY OK ] 44 NW iN ; Ne SCE SSSI ANN NS panne tri wt ey bali ti | wees - WEL Ge wersyy Ui Sofwe roi Wea maf t aa ; ' i Ly cog | we Ok havi b Se es Jeans Malo BUOG oy rial a an = i.| J AR | | KN a eo iy ere Ce BE AL 4 1 et Neteg? z vepeee ty TORE Hs * Avil suits y a Wet ab . ? \ : “ v ; 1 MANY ait alias a a Wy way ee Wnvaynees. tat | | | iv vue re rh vy | Ty a nwino MSL = Se + By vy. a ; Na hia | 1a Nae OE Na i tt nd a hd eae ea tant Fd doy Se ye oe tMOC S| age, s eefit Lenoree Ww leg Tey ety es epee | || ames Maia mire Wi Laan NS nMtinnrersi neni Ayer Wi Rca se eit wre | pa batt | | eps ON ave Seeerro Ny ou 4 Lh had ve il abhian: | oe Sa K ‘ Aah vi aii Vr" act Pe eee 1 SAre F +p a5" veseadtl sey 4 meCAn) 0 oe “yi M Shay Ay, OT Cee it tale \ A : “nde hie wer SIN 4.0 v Sw De m~b eens Plath sk Py Glay Neel Pi een f 2 ] Nou t Hatiivces erin ti weetaegy V4 ahs TESTE SAL EET on POE CUTETCy ines MAA wt LEE xt ike INVA Vv toe Maret q44 R Mab was AW WW RAM Ge. fron Pag v a ~ ; ’ (: FS poe en a : = ™S a cay ae EAA MIRAE Neg | ae au x ict Ser: avinnnnedil bBa 2 vettttt at, ‘i ALLELE att pad Wl TPM | LU paar ||} | | wr) ny i didi LJ Pasa Me vy i fats See pe wine ak VOU Re Wily TEE bi et : ye oT he ei eee, we &S : AT, oe phat | iy ee \ " high aagaitg || wi jks | {io J A hips Toye, het Ae Lo ST ATS = SS erseseeitl Spd eeueege piece z arf | tA OTH AT) sanepaiad gis ye v scahetinn bahar ste Siu a SNe cn “ Nip ane as WI | Mp. BU [oh So ure A : mec rersvcver BUSSE NOCILEL UeU LLU 1 a e ie zk MARASCAR SS a weve’ = ADEA { 5 3 \ woe LT Ss 4 yey 4 y j — Pg SAAN dd i fat Pati ean MAAS i sy mesKAC Gy! | inert’ eld Jt PA 2 i \ v us ¢ é tor. h 1 aay i= i f a [> > 5 A ue ihe aa ; *, Sy 440) TI j Ty Ayes 5 latte Nettie bh YU | yen wn eae oa ide ( . Lf { \ moe : ayes ae te CN ane SEE TERy: wd ‘ is LtTT Pps Bae Sa i ee lar. ‘Sh eh Age! j és @ sae! ey. { Us a | 1 Bi oe Vey . +€ S 4ip [Bees avhet ny : Bes a PNA © & We © We Be AP ire ryt wal! Tig I y a |) \ Rs oie ee US se. ar id Phe a Aly Moth ws “e ~ nut \ : : WiGe Te wt a Ty Snes ‘ wu raw J Fe on? Sd - : i Lae b bi. } : fe “Go Gre ig v' __T.lhlc( D|CwCrLKkttDtl LUC lll lOO OO lll Vey ‘ee: ne | e: Ny NA Defi , = ee Se ay » | b Pach ahh . os, | Cie Ar? wi Ly bul Ava 4 dif ne ere, | ¢ (Vu . ly oy iy aa eds PP idel | phe. yu Cle, ie . AMERICAN JOURNAL OF SCIENCE. JAMES D. anp EDWARD 8S. DANA. ASSOCIATE EDITORS Prorgssors JOSIAH P. COOKE, GEORGE L. GOODALE anp JOHN TROWBRIDGE, or Cameripar, Proressors H. A. NEWTON anp A. BE. VERRILL, or New Haven, Prorgessor GHORGE F. BARKER, or PuinapEeLputa. THIRD SERIES, VOL. XXXV.—-[WHOLE NUMBER, CXXXV.| Nos. 205—210. : Pie ‘ \hser aN it NOLAN POM SOON, isss. / reas 1 o56 lee WITH VII PLATES. Nt fons Wiice rmsann - . -NEW HAVEN CONN.: J. D. & BE, S. DANA. 1888, es ee ey j Tuttle, Morehouse & Taylor, 5 ‘ otk i j 371 State st., New Np CONTENTS OF VOLUME XXXV. Number 205. Page Art. I.—Speed of Propagation of the Charleston Harth- ; quake; by 8S. Newcomps and C. HE. Durron ._--------- 1 II.—History of the changes in the Mt. Loa Craters; by J. D. Dane bart i Kilauea) (Plate), 2 3 ee ie aes 15 IlJ.—Analysis and Composition of Tourmaline; by R. B. INIGGS Ts Nee ver. aie Se RPE ORSEUIS To 2 Wiel ea CCL SLICE I Be 35 IV.—Different types of the Devonian System in North AMELIA OY) TLCS. WV ELE AMS| 1) Sasa oy 6 aa 51 V.—Law of Double Refraction in Iceland Spar; by C. 8. , ETPASTINGS wks Snes as OMe eet Mae ES ie deans ee eae) 60 VI.—Notice of a New Genus of Sauropoda and other new Dinosaurs from the Potomac Formation; by O. C. NIAC lg Rete sy dy ae a A es IS ies Ak cee 89 VIT.—Notice of a New Fossil Sirenian, from California; by O. C. Marsa SCIENTIFIC INTELLIGENCE. Chemistry and Physics. — Decomposition of the Hydrides of the Halogens by Light in presence of Oxygen, RIcHARDSON, 73.—Influence of Liquid water in promot- ing the decomposition of Hydrogen chloride, ARMsrrone, 74.—Concentration of Solutions by Gravity, Gouy and CHAPERON, 75.—Percentage of Oxgen in the Air, HempreL: Constitution of Selenous Acid, MicHarnis and LANDMANN: Indexing of Chemical Literature, 76.—Mechanical Equivalent of Heat, Drer- ERICI: Radiation in absolute measure, BorromMLEy: Maximum of Light Inten- sity in the Solar Spectrum, MENGARINI, 77.—Relation of the wave-length of light to its intensity, EBERT: Brief notice of a paper by Mr. Hallock, Spring, 78.—Lessons in Elementary Practical Physics, Stewart and GEE, 79. Geology and Natural History.a—Communication by Raphael: Pumpelly, 79.—Geo- logical listory of the Swiss Alps, 80.—-Gradual variation in intensity of meta- morphism, 82.—Mission Scientifique du Cap Horn, 83.—The American Geolo- gist: Geology and Mining Industry of Leadville, Colorado, 8. F. Emons: Fifteenth Annual Report on the Geological and Natural History Survey of Minnesota, N. H. WincHErt, 84.--New York Paleontology: Annual Report of the Geological Survey of Pennsylvania: Fossil Mammals from the White River formation contained in the Museum of Comparative Zoology, W. B. Scorr and H. F. Osporn, 85.—Diatomaceous Karth in Nebraska: The Upper Beaches and Deltas of the Glacial Lake Agassiz, W. UpHAM; Supposed diamonds in a Meteorite: Cryptolite: Grundriss der Kdelsteinkunde, P. Grorm: Rivista di Mineralogia e Cristallografia Italiana, R. PANEBIANCO: Catalogue of all recorded Meteorites, O. W. Huntineron, 86.—A chapter in the History of Meteorites, W. Frieut: Das pflanzenphysiologische Praktikum, DETMER, 87. Miscellaneous Scientific Intelligence.—Proceedings of the Colorado Scientific Society: Relative Proportions of the Steam Engine, W. D. Margs: Modern American Methods of Copper Smelting, E. D. Perers, 88. Obituary.— FERDINAND V, HAYDEN, 88, iv CONTENTS. Number 206. Page Arr. VIII.—Seismoscopes and Seismological Investigations ; i bye C MEN DEN H ADL alee eee eee pews eae eee 97 IX.—Petrographical Microscope of American Manufacture ; loys Ge EL 9 WW We LTA MS) SU OS sep co eae ee 114 X.—New Ammonite which throws additional light upon the geological position of the Alpine Rhetic; by W. B. (Sy NaH ca a NEPAL Sti ey ROA Reg or 5 Nal a 118 XI.—Three Formations of the Middle Atlantic Slope; by Weds MicGmi) (Wothke ate iih)) es ese ee eae 120 XII.—Experiments with the Capillary Electrometer of Lipp- mann; by) JEL (PRATT vice ys Ue pael at Sau Bu ye eee 143 XITI.—Period of the Rotation of the Sun as determined by the Spectroscope; by Henry, Crew. 220-222-2225 151 XIV.—Theory of the Bolometer; by H. F. Reip-_------_-- 160 XV.—Are there Deep-Sea Meduse ? by J. W. FEwxkzEs_--- 166 Obituary.— FERDINAND V. HAYDEN, 179. Number 207. Page ART NOV L——ASa, Gmanyis7 iva ADVAN Augen ot Set nr Sheers ee 181 XVII._—Calibration of an Electrometer; by D. W. Suma -.. 204 XVIII.—On the so-called Northford, Maine, Meteorite ; by BUC UENOBENS ON 72.00 G0 20a) 7E SCE saan orgs Je US eer ea 212 XIX.—History of the Changes in the Mt. Loa Craters; by ~ eS eACMSRE S|) TED 2 9D) aia Ses Ns Git Uo IT re is ee eka a 213 XX.—The Taconic System of Emmons, and the use of the name Taconic in Geologic nomenclature; by Cuas. D. Watcorr, of the U.S. Geological Survey2_--22 32-2 see 229 X XI.—On the crystalline form of Polianite; by Epwarp 8. DAN Avand (Sang ri 10. Tem EEG De 26. eae ieee ee 243 SCIENTIFIC INTELLIGENCE. Chemistry and Physics —Stalagmometer and its use in quantitative analysis, TRAUBE, 248.—Apantlesis, a Separation of the Constituents of a Solution by Rise of Temperature, MALLET: Properties of Fluorine, Morssan, 249.—Oxygen Carriers,* LotHar Mryer: Atomic Weight of Zine, REYNOLDS. and Ramsay, 250.—Text-book of Inorganic Chemistry, VicToR von RICHTER, HpG@ar F. SmirH: Manual of Analytical Chemistry, JouNn Muter: New instrument for measuring heat, WEBER, 251.—Velocity of Sound, A. W. Rucker: Transmis- sion of power by alternating electrical currents, T. H. BLAKESLEY: Measurement of Hlectromotive Forces, WiLLIAM THomson: Influence of Magnetism on the Thermo-electric behavior of Bismuth, GIOVANNE PIETRO GRIMALDI: Coincidences between lines of different Spectra, 252 —Influence of thickness and luminosity of light-producing layers, upon the character of Spectra, EBERT: Measurement of force of gravitation, M. DEFrorGES; Influence of temperature on Magnetiza- tion, 253. CONTENTS. Vv Geologi y and Mineralogy—Note respecting the term Agnotozoic, T. C. CHAMBER- LIN, 254.—Contributions to the Paleontology of Brazil, CHARLES A. WHITE: Arkansas Geological Survey: Fossils of Littleton, New Hampshire: Palzeo- lithic Man in No orthwest Middlesex, J. A. Brown, 255.—Organization of the Fossil Plants of the Coal Measures, W. C. WILLIAMSON: Catalogue of the Fos- sil Mammalia in the British Museum, R. LyDEKKER: Geological Evidences of Evolution, A. Hrmprin, 256.—Kilauea: Allgemeine und chemische Geologie, J. RorH: Mineral Resources of the United States, D. T. Day Native Plat- inum from Canada, G. C. HOFFMANN, 257 _—Shepard Collection of Minerals: Natural Gas, 258. Botany—Respiratory Organs of Plants, L. Jost: Combination of the Auxanome- ter with the Clinostat, ALBRECHT, 258.—-Die natiirlichen Pflanzenfamilien, A. ENGLER and K. PRANTL, 259.—Botanical Necrology for the year 1887, 260., Miscellaneous Scientific Intelligence — Hann’s Meteorological Atlas, 263.—New Meteorites, 264. Number 208. Page Art, XXI.—The Absolute Wave-length of Light; by L. ; LRT SU tase ed Pre ae Ua ease NAAN AES ape RTE EE UE TO nat 265 XXIiI.—History of the changes in the Mt. Loa Craters ; by : J.D. Dawa. (With Plates IV and AYA Vela te EI 282 XXIV.—The Electromotive Force of Magnetization ; by He INTeHomsiand: Wi Sag Eh RANT, Miia ee ieee a0 290 XXV.—Notes on certain rare Copper Minerals from Utah ; by W. F. Hititepranp and H. 8. Wasuineton ---- ---- 298 XXVI.—The Taconic System of Emmons, and the use of the narne Taconic in Geologic nomenclature; by C. D. NEA COmiaen(NVAIt eEdate TET Wa POe ians SiN ca sea 307 ae —Three Formations of the Middle Atlantic Slope ; Ve WV Patecdiere Vic Giarerroretenie mipet a eect Oak hs NE SS 328 XXvill —Diorite Dike at Forest of Dean, Orange County, INES see ayes ane IG MiP Het ane Ua Lene UNA Ne yale al 331 XXIX.—New Lecture Apparatus for determination of Re- flection and Refraction; by W. L. Stevens _...._--. 332 SCIENTIFIC INTELLIGENCE. Chemistry and Physics—Spectrum of the Residual Glow, CrooKus, 334.—Pres- ence of Chlorine in Oxygen prepared from Potassium chlorate, BELLAMY: Interaction of zinc and sulphuric acid, Murr and ADIs, 335. — Organic Analysis, A. B. Prescorr: Practical Physics, B, Srewarr and W. W. H. GEE, 336.— Spectrum ot the oxyhydrogen flame, G. D. Liveine and J. Dewak: Application of the Electrolysis of Copper to the Measurement of Electric Currents, GRAY: Influence of light upon electrical discharges: Wave-lengths of standard lines, F. KURLBAUM, 337. Geology and Natural History.—Distribution of strain in the Earth’s crust resulting from secular cooling, C. Davison and G. H. DARwtn, 338.—Lavas of Krakatoa: Geologie von Bayern, K. W. von GUMBEL: Recent contributions to our knowl- edge of the vegetable cell, 341. al CONTENTS. Miscellaneous Scientific Intelligence—Beitrage zur Geophysik, G. GERLAND, 344. Klima und Gestaltung der Hrdoberfliche in ihrer Wechselwirkung dargestellt von J. Propst: Beobachtungs-Ergebnisse der Norwegischen Polarstation Bossekop in Alten, A. 8S. Steen: The Asteroids, or Minor Planets between Mars and Jupiter, D. Kirkwoop: Manual of Descriptive Geometry, C. A, Watpo, 345 —Annals of the Astronomical Observatory of Harvard College, H. ©. PICKERING: Movements of the Karth, J. N Lockyrr: Publications of the Lick Observatory of the University of California, HE. S. Honpen: Cordoba Observations: Elementary Treatise on Analytical Mechanics, W. G. PECK, 346. Obituary.—JAMES C. Booru, 346. Number 209. Page Art. XX X.—The Absolute Wave-length of Light ; by Louis BELLS Part Noe oie 2 poh ih yee an Pees) XXXI.—Three Formations of the Middle Atlantic Slope; by W. J. McGrz. (With Plates VI and VII) .------- 367 XXXIJI.—On some peculiarly spotted Rocks from Pigeon Point, Minnesota: by: We Ss. Bavuny 2° 2) 0. Sees 388 XXXIII.—The Taconic System of Emmons, and the use of the name Taconic in Geologic nomenclature; by Cras. DDEAWE AE CORT! NETO NE AEE ss a Sn es de Sr 394 XXXIV.—Terminal Moraines in North Germany ; by Pro- fessor Re Da SauisBURY: 221s) oc Be ES es ee ee 401 XXXV. —Note on the Viscosity of ‘Gases at High Tempera- tures and on the Pyrometric use of the principle of Vis- COSiby Mwy (CATT oS AIR US) nyse ete ears eine Om SCIENTIFIC INTELLIGENCE. Chemistry and Physics—Boiling-point and molecular formula of Stannous chloride, Bintz and VictorR Mryer: Occurrence of Germanium in Kuxenite, Kruss, 410.—Ilouble Acetate of calcium and copper, RUpoRFF: Ueber die Realktions- geschwindigkeit zwischen islandischem Doppelspat und eimigen Sauren, W. Serine: Integral Weight of Water, T. 8. Hunt, 411 _— Absorption Spectra, Pr STENGER. 412.—Wave- length of the MO red lines of . potassium : Explosion of gases, A. von GiTTINGEN and A. von GERNer: Dust particles in the Atmos- phere, JoHn AI?KIN, 413.—Magnesium and Zinc, Hirn: Gravity, 414. Geology and Mineralogy—Geology: Chemical, Physical and Stratigraphical, J. PRESTWICH, 414.—Level-of-no-strain and mountain making: Geology of Rhode Island; Franklin Society Report: Annual Report for 1886 of the Geolovical Soa of Pennsylvania: Annuaire Géologique universel, Revue de Géologie et - Paléontologie. 415.—The Geological Record for 1879, W. WuiTakeR and W. H. DALTon: Manual of the Geology of India, Part IV, Mineralogy, F. R. MALLET: Brief notes on recently described minerals, 416.-—-Note on Xanthitaue, L. G. Eaniys, 418. Botany and Zoology—Receut contributions to our knowledge of the vegetable cell, Loew and Boxorky, 4!9.—Garden and Forest, C. S. SarGentT: Bibliotheca Zoologica, 420.—Report on the Annelids, of the Dredging Expedition of the U. S. Coast Survey Steamer ‘‘ Blake,” H. KHLERS, 424. Miscellaneous Scientific Intelligence—N ational Academy of Sciences, 424, Obituary—OscaR HARGER, 425.—JULES-EMILE PLANCHON, 426. Propagation of the Charleston Earthquake. 3 nine seconds. Mr. Allan is authority for the statement that its reading next morning was 9:51 exactly. He had received the time signal on August 31st, but as the clock was within the limit of tolerance he did not correct: it. Subject to this limit he had no knowledge of the exact error of his clock and his memory on this point ‘did not serve him The second clock was the regulator which controls the time of the North Eastern Railway. This clock was compared with the’ time signal on August 31st, but was not corrected, its error being within the limit of tolerance, which was eight seconds. It had been reset two days previously. Its reading was 9:51:15. It was stopped by the point of the pendulum catching behind the metallic are in front of which it properly vibrates. The third clock was that which regulates the time of the Charleston & Savannah Railroad. It had been reset two days previously and compared with the time signal on August 31st, and was within the limit of tolerance, eight seconds. Its reading was 9:51:16 and it was stopped in the same manner as the preceding one. The fourth clock was that of the South Carolina Railroad. It had been reset by the daily time signal on the day of the earthquake. Its reading was 9:51:48. Although these records range through an interval of 48 seconds they may be reconciled. The azimuths of the planes of oscillation of their pendulums were as follows: TameseAllamuia CONS oe. ene eek manne ae N. 85° E INortheMassennkvall road, |e 8 ee Bee N. 40° E Charleston & Savannah Railroad__--__-- N. 66° K Southe@arolinagivailroadieis 2). 2hawiee: N. 30° W These azimuths may be put into relation with what is now known concerning the varying phases of the shocks, their respective durations and directions of vibratory motion. The earthquake at Charleston began as a light tremor, steadily in- creasing in power through an interval estimated to be from 10 to 15 seconds’ duration; then suddenly or by swift degrees it swelled into the full power of the first maximum, then sub-. sided to a minimum, then swelled suddenly to a second maxi- mum and lastly died away gradually. ‘The interval from the beginning of the first maximum to the close of the second maximum is estimated at from 35 to 55 seconds; the subsid- ing tremors are estimated at about 6 to 8 seconds: the total duration from 55 to 75 seconds. It may be expressed graphi- cally by the following curve in which the abscissas TEBE Sene time and the ordinates an arbitrary scale of intensity. In the first maximum the waves were mainly normal and came from N. 80° W. In the second maximum the direction of vibration was about at right angles with the foregoing or + Newcomb and Dutton—Speed of about N. 60° E. It will now be seen that the planes of oscil- lation of the first three clocks made wide angles with the di- rection of motion of the first maximum, while the plane of the fourth clock was almost exactly parallel with that direction and perpendicular to the direction of motion of the second max- imum. The fourth clock, then, may easily have escaped arrest ghoim simids Sim2%s s5imsds Sim 40s 51m 50s sem until the second maximum while the other three would have little chance of escaping the first maximum, even if they did not stop during the lighter preliminary tremors. That the sec- ond and third clocks stopped during the first maximum is ren- dered probable by the way in which their pendulums were caught. It would require a considerable acceleration in a di- rection perpendicular to their planes of oscillation and at times when the pendulums were near the extremities of their ares of vibration in order to throw their bobs far enough backward to catch in the manner they did. These two clocks are relied upon as giving the time of the first maximum. The chances ° are, however, that the pendulums were not caught in this par- ticular way during the first three or four oscillations, but went staggering along for a very few beats until finally caught. An interval of three or four seconds was probably occupied in the rapid swelling of the quake from the preliminary milder phase into the full power of the maximum. If we assume for the beginning of the first maximum an instant of time about three or four seconds earlier than that indicated by the two railroad clocks, i. e. 9:51:12, our actual error, it is believed will not exceed four seconds. The clock of James Allan & Co. prob- ably stopped at a slightly earlier phase. If it may be assumed to have been six or eight seconds slow, its stopping would have been easily possible at that phase; for many less sensitive clocks throughout the country were arrested by tremors no more forcible than\those in Charleston at the particular phase thus indicated. We shall reach the same result, 9:51:12, if we throw out the fourth clock as relating to the second maxi- mum and (giving the weight 2 to both the second and third clocks and the weight 1 to the first) take the mean readings of the three. The whole tenor of the evidence from other clocks’ in Charleston points strongly to a time a few seconds later than 9:51 for the first maximum. It is plainly necessary to select some phase of the earthquake in Charleston or at the centrum as the beginning, with which the beginning in all other places must be compared. It must Propagation of the Charleston Earthquake. 5 plainly be a phase at which the shocks had very great power, sufficient to make themselves felt hundreds of miles away. This phase should obviously be that which has been called the beginning of the first maximum. It still remains to find the corresponding time at the centrum. As the speed of propaga- tion is now known to have been in the neighborhood of three miles a second and as the distance of Charleston from the theoretic centrum is 20 miles, the subtraction for the time at the centrum is taken to be six seconds, making the time of be- ginning at that point 9:51:06 standard time of the 75th meridian. The full catalogue was next examined in order to ascertain what reports should be finally rejected. In the final report this catalogue will be published, together with a list of the rejected observations showing the grounds of rejection. For present purposes a summary view of these reports is given, showing the number of observations corresponding to specific minutes or falling betweeen consecutive minutes. Table showing the numbers of reporis corresponding to specified minutes or falling between consecutive minutes. G-AV/eanGe SCCOMUS een ye ais die CL oN Use hs ieee ALR aap EAS ones Uwe ag BEMIS 4 Ue RN al he ARCA HC NAY zed CM Ue bw 3 6S ts) a re ye ry te Re nue eco er cara ea nn AIRS 32 Cea yl ioe etapa tite a geen ele pete, peel EUAN 3 a Map Ne Melee UR Uae 6 Goris AMSEC OMS poe ey een racheanatit ye A Gta eae 6 EO RI MAE IN Sse gL Al eek a ete gD DF On I Se RRL MENG 25 DDT CLES CC ONG Sioa a tty seat IY eT ao PRU tscy 9 COO Ra 3s Be aM Sh Iie A cle a cn et Zl ag NAadae Ae e R O 28 Ca oF ayia Mee NON | fXEX OVO OCG eh cs is es eo (UN Ir NN ho i 16 POOP SS ccc ane Boy Ga Gael sore t Sil OAS AINGASE COM Sy coe ie ee = ae srl i Ac neal ch ULE NEA Ua 9 9 is had Tal gh ay tye ease ara UR TEN Tec Aa &6 9:55 and seconds EBONY Set EN Aca) RET ants i aE 8 S51 aE pas Rea) AS EUE CLR AIM GASES rT A Mn WN te A 21 Ded OVA CUSS COM Sian Ll ile CNT SEAN MN ES Sean at 2 Oe yee CaM RIP tL ae MUN P tel CUNO UNS SOR ty At tents MW Rt 8 REI fe am pipiens Nay SUN 2 RY beh = er Ry USL Pe EK rear A en ae 5 OSHA CASECOMGS kn Cee unraLyce Na nANEDD | Semel il Gy Fay) a rr ch Fee Medloneah year as Baresi AU eR mehr AN HEN ieee 3 VCO) OKO eke or FE ke Sy at OU oh hao a (eae Oe 13 ORO Ve aan ses 7 Ooi MA NEL GIVEN NA UNIS IN cs UALR ay cit 2 BASS (2 arpa em eee eas nan ear mee ELL ne MCN IN yr Ll od 1 ANG Cellemepn te uieRi sence nek PEIN LAR nse aii") Mail, MN Aalae 316+ There are thus four reports giving times earlier than 9:50 and three later than 10 o’clock. The synopsis illustrates well the tendency of people to give time in terms which are multiples 6 Newcomb and Dutton—Speed of of five minutes. Thus we have 32 giving 9:50, but none giv- ing 9:49, and only six giving 9:51. There are 13 giving 10 o’cloeck and there would have been many more of them if the eatalogue had included these which stated the time as being “about” 10 o’clock or “near” 10 o’clock. There are 86, or more than one fourth the whole number, which give 9:55. Every one of the 9:50 reports is rejected. It is certain that they all involve errors greater than one minute too early, and the large number of them would introduce a large systematic error into the mean; and as there is no apparent reason for re- jecting or keeping one observation rather than another, all of them are thrown out. All of the 10 o’clock observations are thrown out. For, upon further examination, all giving 9:58 and seconds, 9:59, 10:01 and 10:02 will be rejected on their merits. This would leave the 10 o’clock reports as an isolated group in an otherwise comparatively orderly series, and its effect would be to introduce an error of unknown magnitude and of anoma- lous character. In dealing with those giving 9:55 there is more difficulty. The following course has been adopted. Wherever a report states clearly, or raises a strong presump- tion, that this was really the nearest minute observed, to the exclusion of any other, it is accepted if otherwise unobjection- able. Where this evidence is wanting the report is rejected. It is quite probable that some thus rejected are very good ob- servations; but it is clearly better to reject many possibly good observations (provided a suflicient number remain) than to admit a few bad ones with the certainty of introducing an un- known error. The number of 9:55 reports thus rejected is 43, which happens to be just one half. Still other observations are rejected on their merits. A ma- jority of these are thrown out for what are presumed to be large unexplained errors. There are 29 of them, of which 15 are rejected for being two minutes or more too early and 14 for being as much, or more than as much, too late, when com- pared with a larger number of much better observations in the same locality or in the immediately surrounding region. The rejection of these 29 observations does not greatly affect the deduced speed, but.it does diminish notably the computed probable error. The total number rejected for all causes is 130 and the number accepted is 186. These have been sepa- rated into four groups, each containing data which are consid- ered to be as nearly homogeneous as possible ; that is to say, in each group the observations are presumed to have the same sources of error, whether accidental or systematic. The first group is required to fulfill the following condi- tions: (1) The report must specify the beginning, or the time when the tremors first became sensible. (2) It must give not Propagation of the Charleston Harthquake. 7 only the minutes, but also the seconds, with an uncertainty not exceeding 15 seconds. (3) It must have been obtained from a clock kept running with accuracy upon standard time or equally reliable local time, or from a clock or watch compared with such time within a few hours of the occurrence. There are five observations besides that of Charleston which meet these requirements. The second group will consist of those which fulfill the same conditions as the first, except that they will be required to give only the minute or half minute nearest to the beginning. There are eleven which answer to these requirements. The third group will include all that remain after taking out groups I, II, and the stopped clocks. Some of these state that the time is that of the beginning, but fail to show that any attempt was made to ascertain the error of the time-piece. Some give a satisfactory account of the time-piece, but fail to state the phase to which the reported time refers. Many do neither the one nor the other. ‘The number of reports in this group is 125. The fourth group consists of accepted reports of clocks stopped by the first great shock. The clocks, however, must be stated to have been regulated carefully by standard time or by local time known to be equally accurate. In all the groups there is more or less discordance among the several observations, no two giving the same speed. As the errors of the first two groups are believed to be mainly of the accidental class, the best method seems to be to submit them to the process of least squares. The equations of condition may be formed very simply in the following manner: The computed time of the beginning at the centrum (which has already been given) must be presumed to have some error, which may be designated by w If ¢, be the computed time at the centrum (9:51:06) and ¢ the reported time at any other locality, then (¢—t,) = the number of seconds in the observed time-interval taken by the wave to travel from the centrum to the place of observation. If D be the distance in statute miles, and y the number of seconds or fraction of a second required to travel one mile, we may form the following equation: «+Dy=t—Z,, in which there are only two unknown quantities, x andy. This implies that the speed is uniform. If this implication differs widely from the truth, indications of it may be expected to appear in the residuals. It is necessary to put the equations of condition into a form in which a time and not a speed shall be the unknown quantity, because the times and not the distances are the data into which the greatest uncertainty enters. If, - putting v for the speed of transmission, we put our equations into the form of v(t — t,).=D, they would be subject to the objection that their uncertain quantities would be the coefti- 8 Newcomb and Dutton—Speed of cients of the unknown quantities and not the absolute terms. The distances from the centrum have been taken from the Land Office map of the United States by measurement with a seale. They are subject to possible errors as great as three or © four miles, but this error is so small in comparison with the best times that the distances may be regarded as sensibly exact. The following reports constitute the first group. For the sake of brevity the full accounts of these reports are here omitted. They will appear in the final work on the earthquake. Grove I.——The best Observations. : Time 9h+- Locality. State. Distance. m. 3s Weight. Observer. Centrum, S.C: 0 51 06 Prof. Newcomb Alex. McAdie. R. Randolph. Washington, D.C. 452 53 20 Washington, D.C. 452 53 23 Baltimore, Md. A487 5320 New York, N.Y. (645 54 30 M. C. Whitney. Dyersburg, Tenn. 569 54 00 Louis Hughes. From these observations the following equations of condition may be formed. me Doe bo bh bo Wt. ‘Resid. e+ y= 0 OG x + 452y = 135°8 4. + 16 a + 487y = 184 | thang e = 569y ==) 174 1 — 08 e+ 645y = 204 Dh MN mec th) By the process of least squares the normal equations are: lov + 4154 = 1258 4154% + 2210196 = 672408 The solution is, a = — 26s + 4°7s.-and y = 0°309 + 0:01. The resulting speed is, 3:°236+ 0105 miles or 5205 + 168 meters per second. Group IL-—-Good reports, giving the time of beginning to the nearest minute or half minute. Locality. State. Distance. Time. Weigh Observer. Centrum, uC: 0 STZ OGE 2 Nashville, Tenn. 438 5330 1 J.D. Leonard. Covington, Ky. 488 53 41 1 Jos. Brookshaw. Pikesville, Md. 490 53 30 1 OC. R. Goodwin. Evansville, Ind. 545 54 1 FE. W. Norton. Cleveland, O. 604 54 1 Wrm. Line. Cleveland, O. 604 54 1 G.H. Tower. Crawfordsville, Ind. 620 54 +E. C. Simpson. Belvidere, INGy nen 54 1 G. W. Holstein. New York, N.Y. 645 54 30 1 a No Y¥ioilerald: Stockbridge, Mass. 765 56 + J. O.Jacot. Albany, IN BOGS es 0) 55 1 W.. (Gs Duekers Propagation of the Charleston Harthquake. 9 From these we may form the following equations. “Weight. Residuals. Re OO) == 0 2 — 16 x + 438y = 144 ] - 98 x + 488y = 155 ah OG) e+ 490y = 144 1 + 6'3 e+ 545y = 174 | — 66 x + 604y = 174 2a +-11°6 ee 620i —— Te 4 +16°6 we + 622y = 174 1 17:2 * + 645y = 204 1 — 56 x + T6sy = 294 On — 584 e+ T70y = 234 1 + 3°1 The normal equations are : 12 @ + 5898°5 y = 1811. 5898°5x% + 35773665 y = 1100677. The; solution gives'¢ = — 1:68. +. 7s. y = 0:31 = 0:014s. The resulting speed is, 3°226 +0147 miles or 5192 + 236 meters per second. Group III consists of reports which fail to give either the means of judging of the comparative accuracy of clocks and watches or of determining to what phase the observation re- fers. Many and indeed the majority of them are defective in both of these respects. Quite probably some of them are good observations but fail to give the evidence of it. So far as errors of clocks and watches are concerned the errors may be considered as belonging to the accidental class. But all errors as to the phase must be systematic. That some of them refer to more or less advanced phases is certain, and it becomes difficult to determine how many of them do so, and how great is the average tardiness. It is obvious that the effect of all such errors is to make the time too late and the resulting speed tooslow. The general indications are, however, that this system- atic error is not a large one. By comparing miscellaneous reports from those cities which have also given better verified reports belonging to groups I and II there seems to be a ten- dency of the average value of this error to fall between one- tenth and one-twentieth of the mean value of the time-interval. In discussing this group it seems unnecessary to go to the length of formulating a hundred equations of condition, and an equally good result or even a better one may be obtained by the following more summary process. We may take them in sets, the first of which shall comprise all times within 200 miles of the centrum, the second set all between 200 and 800 miles, the third all between 800 and 400 miles, and so on until the last, 10 Newcomb and Dutton—Speed of which shall comprise all beyond 800 miles. In each set we may then take the weighted arithmetic means of the times and dis- tances as if they were single observations. Group III.—Zist of 125 miscellaneous Time Reports. Locality. Statesburg, Columbia, Savannah, Augusta, Laurinburg, Darien, Brunswick, Macon, Jacksonville, Fernandina, Olustee, Palatka. Thomasville, Wytheville, Knoxville, Zellwood, Chattanooga, Norfolk, University, Ashland, Shelby Iron Works, Catlettsburg, Pungoteague, Decatur, Ironton, Nashville, Washineton, Louisville, Baltimore, Dayton, Newport, Cincinnati, Lancaster, Wyoming, Columbus, Hamilton, Paris, Pittsburg, Brookville, New Philadelphia, Sewickly, Mt. Vernon, Wellsville, Oxford, Paducah, Philadelphia, Burlington, Indianapolis, Cairo, Titusville, Helena, Toledo, ’ Newark, Jamestown, State. 8. C. Distance. Time. DX Ov or Or Ot OF Or Cr DDOwwewww pw pw fA 53 30 30 20 27 300; Remarks. mean of 3 obs. mean of 2 obs. mean of 3 obs. mean of 2 obs. mean of 4 obs. mean of 2 obs. mean of 6 obs. mean of 4 obs. mean of 2 obs. mean of 3 obs. Propagation of the Charleston Earthquake. 11 Locality. State. Distance. Time. W't. Remarks. Brooklyn. INE GYe 643 54™30s 3 mean of 4 good obs. New York, INES: 645 54 12 6 mean of 10 obs. Hackensack, Nigidle 654 54 1 Warwick, INE: . 661 56 i Gowanda, Aland 666 55 1 Detroit, Mich. 675 55 12 3 mean of 5 obs. Valparaiso, : Ind. 705 53 1 London, Ont. 706 55 il Peoria, Til. 710 55 1 New Haven, Conn. a 55 30 2 mean of 2 obs. Port Huron, Mich. 712 55 1 Hudson, INES T47 57 1 Hartford, Conn. 147 54°45 2 mean of 2 good obs. Stuyvesant, INGE 760 57 iL Kast Saginaw, Mich. 766 58 ] Albany, INEYSs 770 56 40 1 Fonda, INGEYe 715 55 il Saratoga, NeeYs 797 53 1 Greenfield, Mass. 799 55 il Keokuk, Iowa. 810 boy NPV Dighton, Mass. 812 56 1 Davenport, Ta. 827 55 il Lake Placid, INE AYS: e27 55 1 Jamaica Plain, Mass. 828 57 1 Blue Mt. Lake, IN DG 830 56 1 Bellows Falls, Vt. 832 53 1 Boston, Mass. 832 55230) ) i 2obs! Dubuque, Ta. 878 57 il Prairie du Chien, Wis. 924 ND. Bl) (val Taking these in groups in the manner just indicated we have: Weight. Residuals. Centrum otal Ook) 2 + 4:06 0 to 155 Gy JM e) 9 = 1-90 208 to 284 « + 240y = 84 8 Be oO 302 to 377 xe + 342y = 122 7 — 4:43 405 to 49] x + 462y = 158 16 — 60 501 to 588 xe + 542y = 184 18 — "05 608 to 675 COLO)? Iii, 20 + 1°80 70510799 «© + 744y = 255 15 = 4°00 810 to 924 e+ 837y = 278 jal + 3°85 The normal equations are: 106% + 55768y = 18940. 55768a + 34474772y = 11668675. The solution gives ¢ =+ 4:06 + 1°7 seconds, y = 0°3319 + 00029. The resulting speed is, 3013 + 0:027 miles or 4848 ++ 43 metres per second. To this result some correction must be applied for the systematic error, which, as already stated, there is reason to believe probably lies between one-tenth and one-twentieth of the mean. time-interval and therefore of the speed. Suppose it be taken at one-fifteenth of the amount, with a probable error of one third of the correction. This ° 12 | Newcomb and Dutton—Speed of would make the corrected result 3°214 + 0:072 miles.or 5171 +116 metres per second. STOPPED CLOCKS. It is natural to suppose that if a clock were stopped by an earthquake and if its error at the time were known it would give the best possible record of the time of advent of the shock. An examination of the time reports of this earthquake, how- ever, strongly contradicts this conclusion. A clock may stop at almost any phase of the disturbance. A sensitive one may pass through an earthquake of considerable violence and not stop at all. A jeweler’s clock in Charleston was found going the next morning, and when the telegraph wires were re-opened its error was found to be small, showing that its escapement had missed very few beats, if any. Clocks in Columbia, Savannah, Augusta and Wilmington, N. C., in many cases kept going. Inquiry at Wilmington elicited the reply that no jewelers’ clocks had been stopped. Several reports describe clocks whose rates are satisfactorily vouched for but whose times can be ac- counted for only upon the theory that they were stopped by the second powerful shock, which was felt at Charleston about five minutes after the principal one, ¢ g., Branchville, 8. C., Augusta, Rome, Ga., Cape Canaveral, Camden, Ala., Memphis, Tenn. There are some cities where the time of beginning is well established by independent observation and which also re- port stopped clocks. In every such ease the time of the stopped clock is much later. Thus at Nashville the time of beginning was noted by a clock which continued going for 42 seconds and then stopped. Similar means of comparison come from Cincinnati, Covington, Ky., Pittsburg, Newark, N. J., Brooklyn and New York. And in general wherever stopped clocks can be compared with really good personal observations they invari- ably show a later timie and usually a much later one. The dif ference is plainly due to the fact that it generally takes a con- siderable time and an accumulation of the effects of the vibra- tions of the building upon the pendulum to stop a clock. An attempt has been made to evaluate this difference by taking those cases where a comparison can be made between the read- ings of stopped clocks and independent determinations of the times of the beginning in the same locality. Intervals by Intervals by Locality. State. personal obs. stopped clocks. Ratios. Weights. : Seconds. Seconds. Nashville, Tenn. 144 186 1°29 2 Covington, Ky. 155 235 1°52 1 Cincinnati, O. 155i 195 1:26 2 Pittsburg, ia 174 © 234 1°34 1 Brooklyn, IN-BYe 204 934 1:15 if New York, N.Y: 204 249 122 2 ' Mean ratio, 1°28 Propagation of the Charleston Earthquake. 13 In the above table the comparison at Cincinnati takes account only of a single clock, whose error happened to be known ex- actly. The time of beginning in that city is also known with exceptional certainty and accuracy. It will not differ more than eight or ten seconds from 9h. 16m. (Cincinnati local mean time or 9h. 58m. 41s.). If we consider Cincinnati and suburban towns within fifteen miles of the city which are supplied with local time from the Cincinnati observatory, we have no less than twenty-two time reports, of which nine are stopped clocks. ‘Two personal observations giving 9:15 local have been rejected because they are multiples of five. One report giving 9:17:45 has been rejected because its author, be- sides indicating that it refers to an advanced phase, throws doubt on his own observation. Of the remaining ten personal observations one gives 9:15:40, eight give 9:16, and one gives 9:16:30. Of the stopped clocks, three were in the central of- fice of the Western Union Telegraph Co. They kept standard time and were read only to the nearest minute. All three are reported to have stopped at 9:54. The clock in the fire tower is the one whose error was known. Its corrected reading was 9:16:40. The remaining elocks gave (9:15), (9:16), (9:17), (9: 17:20), and (9:19). Four of the latter were from the suburban town of Lockland. Reducing to standard time and taking their mean, the ratio of the time-interval by stopped clocks to that by personal observation is 1.26, a result identical with that de- rived from the clock in the fire tower alone and nearly the same as that in the table. There is reason to believe, however, that this ratio is a little too great for the mean of stopped clocks throughout the entire country, and especially so for those of very distant localities; for if the ratio were uniform, the absolute differences between the two kinds of data would be very wide in remote regions and small near the centrum. This is not the case. The absolute differences at very remote localities are very little, if any, greater than those at the middle distances. This difficulty prevents us from assigning any specific value to the correction and from determining its prob- able error. Nevertheless the comparisons just made indicate that the systematic error is probably of such magnitude that, if due allowance were made for it, the corrected result for the stopped clocks would not differ much from those of the pre- ceding groups. While this group furnishes evidence which strongly supports the approximate correctness of the results of the other three it cannot be a source of greater precision nor can it furnish the means of reducing the final probable error. 14 Newcomb and Dutton—Speed of Earthquake, ete. Group IV.—Stopped Clocks. Locality. State. Distance. Time. No.of clocks. W't. Centrum, SaGe 0 51™06§ Charleston, 8. C. 20 Sie iky 4 3 Columbia, 8. C. 89 51 2 2 Savannah, Ga. 89 bilieoo 2 2 Langley, 8. C. 103 53 1 1 Augusta, Ga. ital RQ 1 1 Cochran, Ga. 192 52 2 2 Macon, Ga. 203 51130 1 1 Jacksonville, Fla. 211 59 1 1 Atlanta, Ga. 252 OX DD 4 3 Catlettsburg, Ky. 405 53 1 1 Nashville, Tenn. 438 54 12 ] 1 Columbus, Miss. 481 56 i 1 Covington, Ky. 488 55 1 if Cincinnati, O. 49] 54 3 2 Cincinnati, O. AQ91 54 21 1 1 Meridian, Miss. 500 54 iL 1 Lockland, O. 505 54 26 4 3 Havre de Grace, Mad. 515 55 1 1 Pittsburg, ae 525 55 1 1 Neweastle, Del. 538 54. 1 1 Atlantic City, Newel: 552 54 1 1 W ooster, O. 558 55 45 1 1 Newcastle, Pa. 565 B5 il 1 Indianapolis, Ind. 581 55 if 1 Memphis, Tenn. - 587 54 50 6 4 Cairo, Til. 588 53 1 1 Meadville, Pa. 608 55 i 1 Newark, MINE Apa 640 55 1 1 Brooklyn, INE 643 5d it 1 New York, INE Ye 645 By 5) 2 1 Ithaca, NEY 696 55 1 1 Manistee, Mich. 855 57 1 1 We may arrange these in groups or sets according to their distances, as was done in the discussion of group III, and ob- tain the following equations of condition. Weight. Residuals. Oto 89 e+ 59y= 15 7 + 12°29 103 to 192 BB a MOS OS) 4 = = 52) 203 to 252 x2 + 234y = 110 5 — 16°37 405 to 491 x + 469y = 194 7 — 11°29 500 to 588 x + 549y = 209 16 + 4:04 608 to 696 x + 642y = 237 5 + 12°80 855 we -+ 855y = 354 1 — 24°97 The normal equations are : 45a + 183335 y = 7172. 18335x% 4+ 9567895 y = 3717233. J. D. Dana—History of the Changes in Kilauea. 15 From which 2 = + 5:0, y = 0:379. The resulting speed is 2°638 + 0°105 miles, or 4245 + 168 meters per second. If the correction for tne systematic error has a value approximately that which has been derived from the comparisons of the stopped clocks with well determined times of particular locali- ties, or not less than one-fifth the amount, the corrected speed would be from 5100 to 5200 meters. We may now proceed to combine the results of the first three groups and obtain from them a single mean. The probable error of the fourth group being uncertain it is necessary to omit it. Taking the weights inversely as the squares of the probable errors we have: t. Group I, 5205” + 168™ Group IT, 5192™ + 236™ Group ITI, 5171™ + 116™ Mean result, 5184™-+ 80™ mas It remains to inquire whether the data indicate any variation of the speed. The answer is in the negative. The data are inconsistent with any variation of a systematic character and there is no apparent means of detecting an unsystematic one. A small irregular variation, such as might be caused by varying density and elasticity of the propagating medium, would not be inconsistent with the data; but the evidence of it cannot be separated from the errors of observation. Art. Il.—History of the changes m the Mt. Loa Craters ; by JAmes D. Dana. Part I. Kitaveas. (With Plate I). [Continued from vol. xxxiii, p. 433 (June), vol. xxxiv, p. 81 (August), and p. 349 (November). | 4, GENERAL SUMMARY, WITH CONCLUSIONS. From the foregoing review of publications on Kilauea, it appears that we have already much real knowledge about the changes in the crater, and that this knowledge embraces facts that are fundamental to the science of volcanic action. This will be made more apparent’ by the Summary and Con- clusions which follow. It will be convenient to consider, first, the Historical conclusions, and secondly, the Dynamical. I. HISTORICAL. 1. Periodicity or not in the discharges of Kilauea. In the sixty-three years from 1823 to 1886, there appear to have been at least eight discharges of Kilauea. Four of them were of prime magnitude—those of 1823, 1832, 1840 16 J.D. Dana—History of the Changes in Kilauea. and i868—distinguished by a down-plunge in “he floor of the crater making in each case a lower pit several hundred feet deep. Others, as those of 1849, 1855, 1879, 1386, were minor discharges, discharges simply of the active lakes, without any appreciable or noticed sinking of the floor of the crater. The eruption of 1849 might be questioned; but it was preceded by far more activity in the crater than that of 1886. Other subterranean discharges may have occurred since 1840 of which no record exists. Even small breaks below might empty Halema’uma’u. The mean length of interval between the first three erup- tions was 8 to 9 years (xxxiv, 81). The great eruption of 1789, the only one on record before that of 1828, occurred 34 years back of 1823, or 4 x 84 years; and the 1868 eruption was 3 X 94 years after that of 1840. _ The above approximate coincidences in interval and multiples of that interval seem to favor some law of progress. But it is not yet proved that they have any significance. The minor eruptions which have been referred to above have intervals varying from 6 to 13 years. Moreover, looking to the summit crater of Mt. Loa for its testimony, we find still greater irregu- larity, the successive intervals between its six great outflows from 1843 to 1887 being 9, 4, 34, 9, 123, 64 years. A partial dependence of the activity of the fires on seasons of rains was suggested by Mr. Coan; and there is some foundation for the opinion in the times of occurrence of the Kilauea discharges mostly within the four months, March to June, as shown in the following table: 1823 March? : 1855 October. 1832 June (Jan. ?) (xxxili, 445) 1868 April 2. 1840 May. 1879) , Aprils2ie 1849 May. 1886 March 6, In addition, there was a brightening of the fires around the crater in October of 1863; and again in May and June of 1866; whether followed by a discharge of the Great Lake is not known. The future study of the crater should have special reference to this point. 2. Mean rate of elevation of the floor of the crater after the great eruptions. After the eruption of 1823, between the spring of that year and October of 1829, an interval of 6% years, the bottom, if the depth was 800 feet as inferred after the measurement of the upper wall by Lieut. Malden, rose at a mean annual rate of 188 feet, or, taking the depth at 600 feet, of 93°3 feet. Lieut. Malden’s 900 feet for the upper wall, J. D. Dana—History of the Ohanges in Kilauea. 17 sustained, after explanation (xxxill, 440), may need reduction on the oround that the present width of the erater is greater than in 1825, owing to falls of the walls; but it is useless with present knowledge to make any definite correction. Only general results are possible. After the 1832 eruption, the lower pit in February of 1834, was 362 feet deep, by the barometric measurement of Mr. Douglas,* and in May of 1838, about 44 years later it was filled to within 40 feet of the top; whence the mean annual rate of 714 feet. After the 1840 eruption, between January, 1841, and the summer of 1846, 53 years, the 342 feet of depth, found for the lower pit by the Wilkes Expedition, was obliterated, and the floor was raised on an average 40 or 50 feet beyond this; a rise of 400 feet in the 53 years would give for the mean annual rate, 722 feet. Subsequent to 1846 the rising of the floor was slower. Between 1846 and 1868, 22 years, the rise over the central plateau is estimated at 200 feet. It is not certain that subsi- dences in the plateau of greater or less amount did not take place at the eruptions of 1849 and 1855, or at other times. 3. Levels of the floor after the eruptions of 1823, 1832, 1840, 1868 and 1886. The measurements of depth already given and the mean annual rate of progress deduced are approximate data for determining the depth of the lower pit as it existed immediate- ly after the great eruptions. The Geet after the 1823 eruption is considered above. To arrive at the depth after the 1832 eruption, the depth obtained in 1834 by Douglas has to be increased by an allowance for change during the previous year and a half, which, at the rate arrived at above, would give 450 feet. This is so much less than the estimate of Mr. Goodrich (xxxiii, 446) that it is almost certainly below rather than above the actual fact. For the depth in June 1840, the Wilkes Expedition measurement, 342 feet, should be increased for a preceding interval of seven months, which at the rate deduced above for the next four years, would make the amount about 385 feet. In 1868, according to the two estimates a i lower pit (xxxiv, 92), the depth was about 300 feet. . Severance of Hilo, in- formed me in August last that the ah in 1868 was as deep as in 1840. The lower estimate is adopted beyond. In 1880, the lower pit of 1868 had wholly disappeared, and, according to * See the first part of this paper. vol. xxxiii, p.446, June, 1887, where the facts are definitely given, and also other evidence. AM. JOUR. ScI.— THIRD SwurRies, VoL. XXXV, No. 205.—Jan., 1888. 9 a 18 J.D. Dana—TMistory of the Changes in Kilauea. the description of Mr. Brigham (xxxiv, 95, from page 20 of the same volume) the bottom of the crater had already the form of a low eccentric cone, the surface rising from the foot of the encircling walls to the summit about Halema’uma’u. This has continued to be the form of the bottom, and the Government map gives the present depth. (See the accom- panying Plate [).* The following table contains (A) the above deduced figures for the depth of the lower pit; (B) the height of the highest part of the western wall; and (C) the level of the center of the pit below the top of the western wall. Height of W. Wall Height of W. Wall Depth of Lower Pit. above ledge. above centes of ottom. Afier eruption of 1823 600 (800?) 900 (?) Malden 1500 (1700?) 1832 450 (600? ) 71d Douglas 1165 (1315 ?) 1840 385 650 Wilkes + - 1030 1868 300 600 (550 2) 900 (850 2) 1886 0 500 Govt. Survey 380 These numbers have much instruction in them notwithstand- ing all uncertainties. The following diagram, based on them, represents a transverse section of the crater at the several levels of the floor and black ledge. The minimum depths for 1828 and 1832 are here accepted, there being in them no probability of exaggeration. A500 1823 The sides of the pit in this section are made vertical from 1823 onward—an error which there are no data for correcting. * Mr. Brigham’s paper gives results of his barometric measurements in 1880, that are not reconcilable wiih those of the Government or of earlier determina- tions except on the assumption of great changes of level between 1880 and 1886 and small difference of level as regards the base of the cone between 1840 and 1880. His depths are 650 feet at the northern base of the cone near the place of descent, where Wilkes made the depth 650 feet, and the Government map in 1886, 481 feet; and 300 at Halema’uma’u, where the Government survey made the depth nowhere less than 320 feet. By the reported measurements. the cone had a height of 350 feet in 1880, and of 150 in 1886; accordingly the base of the cone to the north had been raised 140 feet in the 6 years after 1880 while nothing or little in the 40 years preceding it, although large overflows during the interval, adding 50 to 100 feet to its height. are mentioned by Mr. Brigham and others; and the level about Halema’uma’u had lost 30 feet between 1880 and 1886. The latter difference of level is not impossible; but the former it is natural to ques- tion, since so great a rise of the border in 6 years could not have taken place by any method without being noticed. + The Wilkes Expedition appears to have made the place of encampment the datum point. The exact position of the place is not precisely known. It may probably be ascertained nearly enough to give by leveling the height with refer- ence to the Voleano House; but at this time the height has not been determined. r a J.D. Pana—Mistory of the Changes in Kilauea. 19 The diminution since 1823 in the height of the western wall above the black ledge is probably due almost wholly to the flooding of the black ledge. According to the numbers, this diminution was about 185 feet from 1823 to 1832; 65 from 1832 to 1840; and 160 feet since 1840. But subsequent to 1840, as Emerson’s map shows, the diminution of level along the black ledge or lateral portion of the pit has been much less than over the central, the amount of diminution at center having been at least 200 feet, and about Halema’uma’u 250 to 300 feet. The bottom of the emptied basin of Halema’uma’u after the eruption of 1886 was 900 feet below the ‘Voleano House; and this was 50 to 100 feet above the liquid lava of the basin in 1840. The relations between the amounts discharged in 18238, 1832, 1840 and 1868 could be approximately inferred from the size of the lower pit as determined by the mean breadth of the black ledge, if the width of the crater were the same at all pe- riods. But in addition to other uncertainties we have that arising from sloping walls, and very sloping on the southeast side. The pit of 1823 should therefore have been narrower at the black-ledge level than that of 1840. Still, the width of the ledge in 1823, according to all the observations and maps, was so very narrow compared with that in 1840, that we may feel sure of the far larger amount of the earlier discharge. But the depth of the lower pit was also greater in 1823, and this requires an addition of one half to the amount which the area of the lower pit suggests, if not a doubling of it. For an estimation of the discharge of 1832 we are still more uncertain as to the mean width of the ledge. But that the ledge was narrow, much like that of 1823, is most probable. In 1868 the down-plunge, according to the most reliable esti- mate, was a fourth less than in 1840, the depth of the pit being not over 300 feet. There are no sufficient data for putting in figures the rela- tive amounts of discharge at the great eruptions. But the general fact of a large diminution in the amounts since the first in 1823 is beyond question. It has to be admitted, however, that we can hardly estimate safely the discharge in 1868 from the size of the pit then made, since the thickness of the solid floor of the crater may have prevented as large a collapse in proportion to the discharge. But it did not take place until 28 years had passed after 1840, and this strengthens the evi- dence as to an apparent decline in the outflows, whatever be true as to the activity. The following eighteen years produced only minor eruptions. 4. Other points in the Topographic history of the Kilauea region. Besides the points considered, the chief events in the topo- graphic history since 1823 are: (1) avalanches and subsidences bo ED: Dana—History of the Changes in Kilauea. along the border of the crater; and (2) overflowings and changes of level over the bottom. Down-falls of the walls and sinkings of the borders are re- ported as having been common during periods of eruption and - earthquake; but direct testimony as to the amount at any time does not exist. In view of the great numbers of deep fis- sures about Kilauea (xxxiv, 358) and the many fault-planes and sunken areas, the fact cannot be doubted; and Mr. Brigham has estimated* that the crater in 1880 was five per cent larger than it was 18 years before. The increase in mean diameter on this estimate would be 300 feet. I think the estimate large. KILAUEA Encamp, i 8. EXPL. EXPED. ment, Encampment above the sca 3970. ft. Depth to Black Ledge 650 to bottom 342° Of the gradual changes over the bottom of the crater pretty full records have been gathered from the published accounts. But we naturally look with the greatest confidence to the maps that give the results of personal surveys, especially with regard to changes in the outline of the walls. We have two such maps—that made personally by Wilkes in 1841, and that by Brigham in 1865, besides the recent map by the Hawaiian * This Journal, III, xxxiv, 20. JS. D Dana—History of the Changes in Kilauea. 21 government, under Professor Alexander’s charge, completed in 1886. For convenient comparison the reduced copies of Wilkes’s and Brigham’s maps are here reprinted ; that of the Government survey is reproduced in Plate 1 of this volume. In using the maps a difficulty is encountered at the outset in consequence of a discrepancy between the first two of the maps and that of the Government survey as to the dimensions of the crater. Accepting the latter as right, the scale of each of the others should be diminished about an eighth to bring the three Re ud CEG Ne aan VA SW coo D i y eZ SS KILAUEA NCE A WM. T. BRIGHAM 1865 maps into correspondence. The maximum diameters in Wilkes’s map, using his own scale, are 16,000 and 11,000 feet; while according to the Government map they are about 14,000 and 9800 feet ; and the length of the line from K to B on the for- mer is 10,000 feet and on the latter 8500 feet. It is certain that the crater in 1840 was not larger at top than now. Mr. Brigham’s map appears to have been carefully made, but for 22 J. D. Dana— History of the Changes in Kilauea. some reason it requires the same correction. Such a diserep- | aney unavoidably throws doubts over other parts of the maps. But while closer study increases confidence in Mr. Brigham’s, the result is not so satisfactory with the Wilkes map. The following remarks suppose the scale of the two maps to have been corrected. Wilkes’s map of Kilauea.—The relations of the map made by Capt. Wilkes to that of the Government Survey is exhib- ited on Plate 1, the outline of the crater from the former being drawn over the latter where it is essentially divergent. This diverging part of the outline is lettered A BC DE, D Eshow- ing the outline of the sulphur banks of 1840. Besides this, the outline of the black ledge of 1840 is indicated by the line LLL, and its surface by cross-lining. Some important features from Brigham’s map also are drawn in and indicated by italic ~ letters. These include small lava-lakes, the outline of Hale- ma’uma’u as given by him, small cones, fissures, ete. The plate shows, in the first place, a general conformity be- tween the eastern wall of the Wilkes and Government maps, but a far greater width of sulphur banks in that of 1840. These sulphur banks have become submerged by the lava flows of later time, and thus the floor of the crater has in this part been extended eastward about 2500 feet. Of this I believe there is no doubt. In the second place, there is no conformity between the maps in the southern half of the western wall. Instead, on Wilkes’s map, south of the Uwekahuna station, the west wall (A BC on Plate 1) is 1200 to 1500 feet inside of the position of the existing wall as given on the Government map; show- ing, apparently, a very great topographical change on- that side of Kilauea since January, 1841, and one of the highest in- terest; a change either by subsidence, or by overflowings of lava streams, adding nearly 10,000,000 square feet to the area of the crater. Looking about for other evidence of this change, and finding no allusion to it in Mr. Coan’s reports, and nothing in Mr. Liyman’s paper or map of 1846 (xxxiv, 83), but, on the contrary, a general conformity in Lyman’s map to that of the recent survey, I was led to question the unavoidable conclusion, although it involved a doubt of the Wilkes map. A conse- quence of the doubt was my sudden determination to revisit Hawaii and sustain the conclusions from Wilkes’s map if possi- ble; for they made too large a piece in the history to be left in doubt. Mr. Drayton’s sketch, reproduced as Plate 12 in a former part of this paper (xxxiii, 437), suggested the method of deciding the question. J. D. Dana—History of the Changes in Kilauea. 28 The conclusion arrived at while on the ground in August last, was that Drayton’s sketch represented sufficiently well the existing outline of that part of the crater, that is, of the crater of to-day. It follows, consequently, that the west wall of 1841 and of 1887 are essentially alike in position, and that Wilkes’s map of the southern half of its western wall is 1200 to 1500 feet out of the way. To make this large correction on Wilkes’s map involves some other large changes; namely, the widening greatly of the black ledge west of Halema’uma’u; and also a probable widen- ing of the Halema’uma’u part of the lower pit with the entrance- way toit. Both changes are favored or required by Drayton’s sketch. The entrance-way referred to is thus widened (on the ground of Drayton’s sketch chiefly), from Wilkes’s 800 feet at top of wall to about 1500 feet. The dotted line L’L’L’ on Plate 1 is believed to show the probable limit of the 1840 black _ ledge along the west border of Halema’uma’u.* So large an error in so small a map excites an uncomfortable query as to all the rest of its details ; fortunately not, however, as to the depth of the crater and its lower pit, since this was obtained by the independent measurements of two of the Expe- dition officers, Lieutenants Budd and Eld. Moreover the map may be used for some general conclusions. Drayton’s sketch was probably taken from the point marked Dn on the map, south of Wilkes’s encampment, or on the higher land to the west of this point.t+ The sketch has three headlands along the west wall. Of these, only the second and third exist as they then were. The first or nearest stood, as the sketch shows, between the Uwekahuna sum- mit and the second of the deep western bays on Wilkes’s map of the lower pit, a spot where great subsidence has taken place in the western wall, east or southeast of the Uwekahuna station (xxxiv, 358); and the sketch appears to be sufficient testimony for the reality of this subsidence and its amount. Looking again at Wilkes’s map (page 20), it is seen that, as al- ready stated, the outer eastern wall has the same position that it has on the Government map, but that the sowtheastern wall of Wilkes is not continuous with his western, but is an independent one situated more to the eastward; and here came in the error. The error is so extraordinarily great that we sought while at the cra- ter for some extraordinary excuse for it. We concluded (Mr. * Another smaller change is proposed in the eastern outline of the lower pit, near ¢, suggested by Brigham’s map. No attempt is made to give on the Govern- ment map Wilkes’s outline of the southeast angle of the crater, as the existing features offer no available suggestions. + While the sketch bears evidence of being generally faithful to the facts, the foreground appears to be modified for the artistic purpose of giving distance to the rest. 24 J.D. Dana—History of the Changes in Kilauea. Merritt and myself) that Captain Wilkes in his visit to “all the stations around the crater in their turn” (xxxili, 451), on reach- ing the high Uwekahuna summit, instead of relying on his angles, probably took the shorter way of sketching in the ridges that stood to the southeast and south; and that he was led by insuffi- cient topographical judgment to throw the wall, together with the parallel ridge outside of it, too far to the eastward. The error, as we saw when there, is an easy one for him to have made. This cramped the map to the southward about the Great South Lakes, but the angles taken from other stations were not enough to serve for the needed correction and the sketching was allowed to con- trol the lines. However this may be, it is lamentable that a cor- rect map, with a careful determination of heights around the crater, was not made in 1840. An important error also exists in Wilkes’s determination of the longitude of his encampment near the crater. The Surveyor- General of the Islands, Prof. Alexander, informed me that the position Wilkes gives Kilauea is 85 minutes too far west; and that the error affects all the southeastern quarter of his map of Hawaii including the position of the coast line. His longitude of the summit of Mt. Loa is correct. Subhas Sys iaps ef , Redhet Cave are eae 0 “ The wh dle iferior <= an elevate oCave plain from 150te 100677 ? ft. alove the peng a Mack Ledagiot ow uneven and sloping northward . \\) Nanny ‘ 7M gunna 2s oviablelayy Bf HTAVEYS Jp0u} Misery , KILAUEA stoping Bankenoy cf descent © Ss. LYMAN eee ie 1846 Mr. Brigham’s map.—Mr. Brigham’s map is a register of the facts of 1864-65, a period just half way between 1841 and 1887. It indicates unfinished changes in progress within the crater which were commenced in 1840, and other conditions that became pronounced only in later years. J. D. Dana—History of the Changes in Kilauea. 25 The remnants it represents of Lyman’s ridge of lava-blocks, —the talus of the lower wall uplifted upon the rising floor of the lower eee already been referred to (xxxiv, 89). That it may be fully appreciated, the reader is directed again to Mr. Lyman’s map, here reprinted with corrections by him ;* and then to Plate 1, which shows these remaining parts of the long ridge drawn, from Brigham’s map, on the recent map of the Government survey (lettered ef, gh). The ridges are not put as far from the east wall of the crater as on Brigham’s map, but are made to accord with the statement of each Lyman and Coan, and of Brigham also, that they followed the course of the lower-pit wall of 1840 a little inside of its position, over the site of the original talus—Wilkes’s position of the wall being adopted except for a short distance near ¢. Halema’uma’u, as the dotted line inside of the basin of the Government map shows, was small in 1864-65, it being only 1,000 feet in diam- eter and but little raised above the level of the liquid lavas. The preceding additional view of the crater is introduced _at this place because it contains the remains of the Lyman ridge as mapped by Mr. Brigham, and is further testimony as to its * The copy of Prof. lyman’s map, reproduced on page 85 of the last volume of this Journal, is not from a tracing of his original map, but from a roughly drawn copy left on the islands. The original was lost by him, as he informs me, when in California on his return to New Haven. He has here placed the ‘‘canal” along side of the ridge, in accordance with the statement in his description and also in his note-book of 1846, which makes the interval between them ‘10 to 40 and 50 yards.” Before publishing the map I endeavored to obtain corrections from him. But on account of his ,illness at the time I could not communicate with him. 26 J. D. Dana—Lfistory of the Changes in Kilauea. position with reference to the walls. The view is from a photograph of a painting made by Mr. Perry, a California artist, in 1864 (?) the year of Mr. Brigham’s first visit, and which | received from Mr. Brigham in March, 1865.* The sketch of the crater bears evidence throughout of great accuracy of de- tail. It has much interest also because it gives, with clear defi- nition, the outlines of the depression (on the left) between Kilauea and the side crater Kilauea-iki;—in which respect it is more satisfactory than Drayton’s sketch. The point of view was on the north border of Kilauea, a little to the east of Drayton’s; and consequently it necessarily differs widely from Drayton’s sketch as regards the headlands of the western wall, yet resembles it quite closely on the eastern side. Halema’u- ma’u is not defined; and this is explained by Mr. Brigham’s map and deseription. Mr. Brigham’s map shows also the positions of active lava- lakes in 1864 or 1865, lettered 2, %, 7, m; and the interesting fact is to be noted that two of them, to the northwest, 7, & lie ai the edge of the black ledge, while 1, m are a little back of it, but in a line with %, &. The long curving line of deep fissures and fault-plane, already reterred to as marking the outline of the Halema’uma’u region, is seen on Plate 1, at a b, not to be concentric with the Hale- mauma’u basin of either Brigham’s map (p. .21) or of the re- cent map; but to that of Halema’uma’u plus the New Lake region of 1884 to 1887. Thus in 1865, when Halema’uma’u appeared as a small basin 1,000 feet broad (not half its existing breadth), the fissure indicated the presence of deep-seated con- ditions as to the fires and forces, that finally ultimated in its extension over the New Lake area. And the expression of this fact in 1865 was doubled by a second concentric fissure 500 feet farther north (Plate 1,¢d). Further, four of the cones mapped by Brigham in the vicinity of Halema’uma’u in 1865, Ps % 7; 8, 00 Plate 1, are inside of the existing Halema’uma’u basin ; and one of the others, 0, is near the north border, and another, ¢, is close by the east side of New Lake. On Mr. Brigham’s map, the position is given of a very large loose block of lava, which is shown at w, on Plate 1. It lies, as is seen, in the northwest part of the crater, and is over the lower edge of what in 1840 (see Wilkes’s map, p. 20) was an inclined but even lava plain to the bottom that had been made in 1840 by an oblique down plunge (xxxiy, 82) carrying the inner side of the great mass down and leaving the other, that against the black ledge, on a level with the ledge, with a broad * See Brigham’s Memoir, page 419, where a wood-cut from it is introduced, but without doing the photograph justice. Mr. Brigham does not state in his memoir the date of the painting. ‘ Perry” is mentioned as the painter on page 468. J. D. Dana—HMistory of the Changes in Kilauea. 27 fissure between. The block probably slid down the slope to its bottom ; and, as the talus at the bottom of the lower wall was lifted on the rising floor to make Lyman’s ridge, so it appears that this loose block was lifted in the northwest corner; and the lift along that part of the crater consisted in the restoring of the half engulfed mass with the lava-block on its surface, to its former horizontal position—the position it had when Mr. Brigham’s map and observations were made. It is interesting to note thus how the 1864-1865 condition of Kilauea grew out of that of 1840, and foreshadowed that of 1887. It is worthy of consideration also that just as the fault- plane @ is concentric with the Halema’uma’u basin plus New Lake, so the far greater Kilauea fault-planes, 2000 to 5000 feet north and northeast of the crater (xxxiv, 358), are concentric, not with Kilauea, but with Kilauea plws Kilauea-iki. 2. DYNAMICAL CONCLUSIONS. General cycle of movement in Kilauea—The history of Kilauea, through all its course since 1823, illustrates the fact that the cycle of movement of the volcano is simply: (1) a rising in level of the liquid lavas and of the bottom of the cra- ter; (2) a discharge of the accumulated lavas down to some level in the conduit determined by the outbreak ; (8) a down- plunge of more or less of the floor of the region undermined by the discharge. Then follows another cycle: a rising again, commencing at the level of the lavas left in the conduit by the discharge ; which rising continues until the augmenting forces, from one source or another, are sufficient for another outbreak. In 1832 the conditions were ready for a discharge when the lavas had risen until they were within 700 or 800 feet of the top; in 1840, when within 650 feet; in 1868, when within 500 or 600; in 1886, when within 350 feet. The greater height of recent time may seem to show that the mountain has become stronger, or better able to resist the augmenting forces. But it also may show a less amount of force at work. In 1823, 1832 and 1840, the down-plunge affected a large part of the whole floor of the crater, which proves not only the vastness of the discharges, but also indicates active lava through as large a part of the whole area preceding the discharge, while in 1886, the down-plunge and the active fires in view were confined to Halema’uma’u and its vicinity. It was not in earlier time, therefore, the greater weakness of the mountain, but probably the greater power of the volcanic forces. The broad low-angled cone which the voleano tends to make, has a great breadth of stratified lavas to withstand rupturing forces. How great may easily be calculated by comparing a 28 J. D. Dana—History of the Changes in Kilauea. cone of 8° or 10° with one of 30°, the latter the average angle of the greater volcanic mountains of western America ; and this suggests important differences in the results of volcanic action independent of those consequent on the possible prevalence of cinder-ejections in the latter. But somehow or other Mauna Loa breaks easily—very easily, its quiet methods say—and it seems to be because such rocks, however thick, can offer but feeble resistance to rupturing voleanic agencies. In the discussion beyond of the operations going on and of their causes, I speak, I, of Kilauea as a Basalt-volcano, the basis of its peculiarities ; II, of the size of the Kilauea conduit; II, of the ordinary work of the volcano; IV, of its eruptions ; and V, of the contrast in voleanic action between Kilauea and volcanos of the Vesuvian type. I. KILAUEA A BASALT—VOLCANO. 1. The mobility of the lavas——The phenomena of Kilauea are largely due to the fact that it is a basalt-volcano in its nor- malstate. By this I mean, first, that the rock-material is doleryte or basalt, and secondly, that the heat is sufficient for the perfect mobility of the lavas, and therefore for the fullest and freest action of such a volcano. It is essentially perfect mobility although there is not the fusion of all of its minor ingredients, that is of its chrysolite and magnetite. This is manifested by the lavas, whether they are in ebullition over the Great Lake, throwing up jets 20 to 30 feet high, throughout an area of a million square feet or more, or when only splashing about the liquid rock and dashing up spray of little lava drops from areas of afew square yards. There is in both conditions the same free movement, almost like that of water, and suggesting to the observer no thought of viscidity. Of the two conditions just mentioned, the former was that of November, 1840, the latter that of August, 1887; and that of August seemed to be the more wonderful, because we naturally look for some of the stiffening of incipient solidification where only a few square yards of lava are in sight. 2. This mobility is dependent largely on the fusibuity of the chief constituent minerals of the lava.—Along with augite, a relatively fusible species, the rock contains, as its other chief constituent, labradorite, almost as fusible as augite, and the most fusible of the feldspars. Andesine and oligoclase are less fusible feldspars, and orthoclase is of difficult fusibility. Thus in this prominent physical character the feldspars widely differ, and accordingly there should be, and are, voleanoes of different characteristics, for example, Andesyte volcanoes, in which oligoclase or andesine is the pre- J. D. Dana—TListory of the Changes in Kilauea. 29 dominant feldspar, and Trachyte and Rhyolyte volcanoes in which orthoclase is a chief constituent; and, besides these, there are also intermediate grades or kinds. The differences in form and action among these kinds of volcanoes depend chiefly on the physical quality of fusibelity, but partly on that of specific gravity. Neither of these qualities, it is to be noted, has any relation to the acidic or basic character of the feldspar or rock, that is to the amount of silica present. The distinction of basic and acidic, of great interest mineralogically and chemically, has in fact little importance in the science of volcanoes, while that of fusibility is fundamental. The most basic of all the felds- pars, anorthite, is as little fusible as the most “acidic” of feldspars, orthoclase, and more so than the equally “acidic” albite.* It is plain therefore that the quality of being baste, does not explain the fusibility of the lavas. Neither “does it explain any other of the physical characteristics on which the peculiarities of the voleano depend. It is also true that the chrysolite (or olivine), the ultra-basie constituent of the lavas, has little influence on their physical characters except through its high specific gravity—which is about 3°3 to 3-4. The mineral chrysolite is infusible, and cannot crease the mobility of the lavas; and there is commonly not enough of it in the Kilauea rocks to diminish the mobility; for a large part of the lava contains less than 5 per cent, and much of it less than -1 per cent. Chrysolite, is ultra-basic ; but this quality has little voleanic importance. It is not the little amount of silica in it that is influential voleanically but the much iron, the ingredient that gives it its high density or specific gravity. The presence of much chrysolite may affect the distribution of the lavas in the conduit, or of the out-flows from the conduit, on account of their high density ; but it does not accomplish this through the ultra-basicity of chrysolite, but through its ultra-ferriferous character, and the conditions under which it is formed. 3, The degree of mobility 1s dependent also on temperature. —lIt is probable, that at the temperature of fusion, or better a little above it, all the feldspars, the least and the most fusible, are nearly alike in mobility. But the lower the degree of fusibility the less likely is the heat to be deficient, or below that required for complete fusion and mobility; and here comes in the great difference among them as regards lavas and volcanoes. The basalt-voleano has special advantage over all others in this respect, as the copious Mount Loa lava-streams and the *Tn my Manual of Mineralogy and Petrography, page 436, I point out further that the distinction of alkali-bearing and not alkali-bearing among the silicates is of much more geological importance than the much used one of acidic and basic. 30 J.D). Dana—LHistory of the Changes in Kilauea. immense basaltic outflows of other regions exemplify. In Hawaii the heat required for the existing mobility is no greater than the deep-seated conditions below the mountain can keep supplied, in spite of cooling agencies from the cold rocks, the subterranean waters and the air; it is no greater than it can continue to supply for half a century and more, as the records have shown ; and supply freely to the top of a conduit 3000 to 3500 feet above the sea-level, and even to the top of another conduit but twenty miles off, rising to a height of 13,000 feet above the sea-level. The temperature needed for this mobility judging from published facts, is between 2000° F, and 2500° F. The fusing temperature of augite and lab- radorite has not yet been determined. We are certain that a white heat exists in the lava within a few inches of the surface; for the play of jets in a lava-lake makes a dazzling net- work of white lightning-like lines over the surface; and white heat is equivalent to about 2400° F. Considering the height of Mt. Loa and the greatness of its eruptions, and the vastness of basaltic outflows over the globe, we may reasonably assume that the temperature needed for the normal basalt-voleano has long been, and is now, easy of supply by the earth for almost any voleanic region; and that the difficulty the earth has in supplying the higher heat for equal mobility in a trachyte or rhyolyte volcano is the occasion of the common semi-lapidified pasty condition of their outflowing lavas. Even if the higher temperature required for orthoclase- lavas, were always present quite to the surface in the volcano, the ordinary cooling influences of cold rocks and subterranean waters and air would be sure to bring out, in some degree, on a globe with existing climatal conditions, the characteristics of the several kinds of volcanoes designated. I do not say that this higher heat required for the complete fusion of trachyte or rhyolyte is wanting at convenient depths below; for it has been manifested in the outpouring of vast floods of these rocks through opened fissures, many examples of which over the Great Basin are mentioned in King’s “Systematic Geology” of the 40th Parallel. But inthe voleano, whose work, after an initial outflow, is carried forward by periodical ejections and requires for long periods a continued supply of great heat, the more or less granulated or pasty condition of the outflowing orthoclase-bearing lava streams is the usual one. Consequently, when a volcano changes its lavas from the less fusible to the more fusible, as sometimes has happened, some change in the features of the volcano should be looked for, except perhaps when the change occurs directly after the initial discharge. J. D. Dana—History of the Changes in Kilauea. 31 Here the question suggests itself whether the temperature existing at depths below may not be one of the conditions that determine whether the discharged lavas shall be of the less fusible or the more fusible kind. But a dasalt-voleano also may fail to have heat enough for perfect fusion, and hence have partially lapidified or pasty lavas, and thus be made to exhibit some of the characteristics of the other kinds of volcanoes. This condition may result from three causes: (1) A decline in the supply of heat of the conduit, as when the partial or complete extinction of the vol- cano is approaching; (2) When the lava is discharged by lat- eral openings or fissures, in which case the lateral duct of lava may not be large enough to resist completely the cooling agen- cies about it; (3) The sudden entrance of a large body of © water into the conduit. The effects from the jist of these conditions—declining heat connected with approaching extinction—are strikingly exem- plified in two great volcanic mountains of the Hawaiian Islands, Mt. Kea on Hawaii, and Haleakala on Maui. Those of the second, in which the ejections are from lateral openings, are abundantly illustrated in the cinder and tufa cones of the islands, and also in widespread cinder or ash deposits through the drifting of the ejected material by the winds. ‘The third, a sudden incursion of waters through an opened fissure, if a possibility, should both lower the temperature and produce vio- lent projectile results, and even Kilauea bears evidence of at least one eruption of great magnitude which was thus catastro- phically produced ; for the region bordering the crater on all its sides, and to a distance of ten or fifteen miles to the southwest, ~ is covered with the ejected stones or bowlders, scoria and ashes of such an eruption. 4, Eruptive characteristics of a Basali-volcano.—tThe ob- vious results of superior mobility and density in lavas, are, as in other liquids: (1) First: greater velocity on like slopes, and thus an easier flow, with less liability to be impeded by obstructions; a lower minimum angle of flow, and consequently a less angle of slope for the lava cones. (2) Secondly: The vapors ascending through the liquid lava encounter comparatively feeble resistance, and hence the ex- pansive force required for escape of bubbles through the lava to the surface is feeble; and so also are the projectile effects due to the explosion of the bubbles. Hence the projected masses com- monly go to a small height—it may be but a few yards—and fall back before cooling, instead of reaching to a height that involves their cooling and solidification in the fall and the making thus of cooled fragments of lava or scoria, called cinders and volcanic ashes. 32 J. D. Dana—Lfistory of the Changes in Kilauea. The projectile process in the basalt-voleano, as long as it is in its normal stage, makes not cinder-cones, but drzbblet-cones, 15 to 40 feet high, out of the projected masses, the falling driblets becoming plastered together about the smaller places of ejec- tion. Such cones consist of cohering drops, clots, pancake-like patches, or abortive streamlets, and form into spires and col- umns on rude bases and take other fantastic shapes. They are necessarily small, and mostly of blow-hole origin, because when the vent is broad, like a lava-lake, the jettings fall back into it again; yet enough may fall on the margin of a lava-lake to eradually raise and steepen its border. Such driblet-cones are of all angles from 30° to 90°. Among the projectile results of voleanoes, driblet-cones are at one extremity of a series, and cinder or tufa cones, many hundreds of feet high, at the other. A cinder cone of 1000 feet in height has 15,000 to 20,000 times the bulk of any driblet-cone. The process is one; but the result varies with the mobility and fusibility of the lavas. Further: in the great lava cone of a basalt-voleano in its nor- mal stage, cinder or tufa deposits rarely alternate with the large lava-streams, while they commonly alternate in other kinds of volcanoes. Further: cinder.cones and beds of volcanic ashes may form about a basalt-vocano, as already explained, whenever the con- dition of insufficient heat is in any way occasioned. The above views as to the characteristics of a normal basalt- voleano are sustained by the facts from the voleanic mountains of all the Hawaiian Islands. In the first place, the slopes are not only the lowest possible, usually from 1° to 10°, but continuous flows of 10° to 90° occur. I have seen many of them descending as unbroken streams vertical precipices on southern and western Hawaii. Again the alternation of the lava-streams of the great volea- noes with deposits of voleanic sand, scoria or stones that were ejected from the great craters, is of rare occurrence, and such deposits make only thin beds of the kind whenever they occur. In such examinations as I have been able to make of the walls’ of Kilauea and Haleakala, and of the precipices and bluffs of Oahu, I have not succeeded in finding cinder or tufa deposits among the layers. The walls of Kilauea are stratified from top to bottom, but with lava-streams, and comparatively thin streams; I could find no evidence, in my examination of its walls, of any intervening stratum or bed of scoria, tufa or stones like that which now covers its border. This testimony is not conclusive as to the absence of such projectile eruptions in former times, for thin beds of scoria or sand like that just re- ferred to—its thickness is only 25 to 30 feet—might be fused J. D. Dana—HMistory of the Changes in Kikauea. 33 and annexed -to the succeeding lava-flow. But the evidence against great tufa deposits, excepting those from lateral ejec- tions, is, I believe, sufficient; and by great I mean 50 or 100 feet; not the 1000 feet and more common in the regions of the Rocky Mountains and the Pacific border. On the island of Maui, I found no such beds of projectile origin in the walls of Haleakala, or in those of Wailuku valley the probable crater cavity of western Maui. On Oahu, the pitch of the layers of lava along the Manoa and Nuuanu val- leys is only 1° to 8°; and in the precipices and bluffs which bound them I saw no layer of tufa. .The thick tufa deposits are confined to cinder and tufa cones, and these are common.* This point needs investigation; for the existence of even thin tufa beds in alternation with the lava beds of the great volcanoes of the islands, may still be true, and such facts would have much interest. 5. The crater of a basalt-volcano is the same in origin, history and functions as those of volcanoes of other kinds, but differs usually in form.—The crater of a great voleano probably has always its beginning—as I set forth in my Exploring Expedi- tion report—in a great discharging fissure. But once open, it usually continues open until a temporary or final decline of voleamic action, whatever the kind of voleano. It continues open because (1) of the fixed position of the supply conduit; because secondly of the conduit-work going on through it in the discharge of vapors and lavas; and because, thirdly, of the down-plunges in the crater consequent on the undermining which the discharge of the conduit occasions. The open end of a deep-reaching conduct determines thus, by its discharges and the subsequent underminings, the existence of the crater; and the crater, by the work done within and about it, makes the volcanic cone. This appears to be the order of rank or im- portance in the phenomena—the crater begins in the opened fissure and is the indicator and future builder of the cone. In the history of the volcano, the era of summit outflows may pass, and only lateral discharges take place; and still the dis- charge of vapors from the lava-conduit and the accompanying movements in the lavas, together with the down-plunges in the erater following the discharges, will keep the crater, or por- tions of it, in continued existence, and the work of eruption or outflow, if subaerial, is still adding to and shaping the cone. This is the present stage of Kilauea and Mt. Loa; and these are the results as they exemplify them. ‘The action, functions * The cinder or tufa deposits of lateral cones have often great extent. This is well seen on Oahu where Diamond Hill, Punchbowl, and the region about Aliapaakai or the Salt Lake, are examples. Am. Jour. Sci.—TuHirp Series, Von. XXXV, No. 205.—JAN., 1888. 3) v 34 J. D. Dana—History of the Changes in Kilauea. and processes are the same whether the lavas fill up to the summit before cutflowing, or become discharged at a lower level by an opened fissure. Examples in the Hawaiian Islands teach also that volcanoes may end with an open crater over 2,000 feet deep, like Halea- kala, a cone 10,000 feet high, or with a filled crater, as in the case of Mt. Kea, 18,800 feet high. The preceding remarks about the permanence of craters apply to other kinds of volcanoes as well as the basaltic; but in the form of the crater the basalt voleano has peculiarities, owing to the mobility of the lavas and the paucity of cinder dis- charges. The ordinary crater of such volcanoes is pit-like, with the walls often nearly vertical, and the floor may be a great, nearly level plain of solid lavas. The liquid material of the extremity of a conduit works outward from the hotter center, through the fusing heat and the boiling and other cauldron-like movements; and hence, where the mobility favors freedom of action in these respects, it tends to give the basin or crater a nearly circular form with steep sides—an ex- planation I give in my Expedition report. Besides, when the discharge takes place there is usually a fall of the walls which is still another reason for vertical sides, and the pit-like form. The small lava-lakes of Kilauea, and the Great South Lake also after a discharge, (or an eruption as it is usually called) are literally pit-craters. Such was the condition of the Great Lake after the eruption of 1886. They all illustrate how the great pit-crater, Kilauea, was made. The lower pits of 1823, 1833, 1840 are other examples. Such pit-craters are normally circular; but where there isa large fissure beneath the crater, they may be much elongated. From the considerations which have been presented we see why the volcanic mountains of the Hawaiian Islands, with slopes rarely exceeding 10° in angle, differ so widely from the great andesyte cones of western North America, with their high slopes of 28 to 85 degrees. We see that the fact of be- ing basalt-made means much in a volcano; that it affects pro- foundly all the movements and the results of those movements as well as the shapes of the mountains and of their craters, [To be continued. ] LR. B. Riggs—Composition of Te ourmaline. B5 Art. IIl.—The Analysis and Composition of Tourmaline ; by R. B. Riees.* Apart from the work by Rammelsberg (Pogg., Ixxx, 449, Ixxxi, 1, exxxix, 379, 547), very little has been done toward solving the question of the composition and constitution of the varieties of tourmaline. Their apparent complexity and the difficulties attending the determination of certain constituents have possibly turned many aside, possibly also the impression that with Rammelsberg’s investigations the matter was settled. While Rammelsberg’s work was comprehensive and was good for the times, his analyses are so seriously faulty in certain important respects, as to justify a new investigation. Though the direct estimation of both water and boric acid would seem to be of the highest importance, before any satisfactory conclu- sions could be reached with reference to the constitution of tourmaline, we find that, having failed in one single attempt to determine the water directly, he falls back on the loss on igni- tion, deducts therefrom an amount equal to the amount of sili- con tetrafluoride, representing the fluorine found in the mineral, and calls the balance water. He takes it for granted that the fluorine is driven off quantitatively. But while this supposition is questionable, it is not the ground of objection. In the re- vision (Pogg., exxxix, 379) of his earlier work, Rammelsberg comes to the conclusion that the iron contained in tourmaline is all there in the ferrous condition, yet wholly ignores the fact of its possible oxidation on ignition, especially an ignition such as would be necessary to expel the fluorine. Ina few cases boric acid is determined directly, but by amethod (Stromeyer’s) which has ever been counted one of the most unsatisfactory. In the majority of the analyses it is estimated by difference. But if the results called water are incorrect and low, as they surely are, the boric acids ought to be correspondingly high or the analysis must be elsewhere at fault. The direct estimation of water being possible, and a satisfac- tory method for determining boric acid having lately been de- vised by Dr. F. A. Gooch, (Am. Chem. Jour., Feb., 1887), new tourmaline analyses seemed desirable. Through the kind- ness of many, abundant and varied material has been at my disposal. * An abstract of a paper which is to appear in a forthcoming Bulletin of the U. S. Geol. Survey. 36 Jie oy Riggs—Composition of Tourmaline. Methods of Analysis. A few words on the methods of analysis may not be out of place here, that the character of the work may be the better judged. Water.—The water was directly determined by igniting a mixture of the mineral and carbonate of soda in a Gooch tubu- lated crucible, the sodium carbonate being used to hold back any fluorine that might otherwise be driven off. The carbonate of soda used was first fused, and then, in order to ensure perfect dryness, the mixture of mineral and reagent was again dried in an air bath at 105° ©. for two or three hours. This estimation, as wellas all the other more important ones, was made in dupli- cate. Boric acid.—Where the tourmaline contained fluorine, the same portion was used for determining both the boric acid and the fluorine, the filtrate, from the mixed carbonate and fluoride precipitates, being used for the estimation of the boric acid. The borate of lime, which may be formed, is sufficiently soluble in hot water so that no difficulty is experienced in bringing it quantitatively into the filtrate. After evaporating this filtrate to a conveniently small volume, it is brought into a retort and acidified with nitric acid. The boric acid is then volatilized as methyl borate, according to the Gooch method, and weighed as borate of lime. It is scarcely necessary to say that throughout this treatment, nitric acid should be used as the neutralizing reagent, and that, if care be taken in its use, in no case need the amount of salt, which is to be br ought into the retort, become inconveniently great. Where no fluorine is present, the soda fusion may be digested with water at once, the solution, con- taining the borate of soda, filtered off, neutralized and treated as above indicated. One might save himself even this filtration, but for the fact that, in using the whole fusion, a quantity of bases would thus be brought into the retort, which, even at the low heat required by the | “distillation, give up their nitrie acid, thereby rendering the determination, j in its after stages, both more difficult and possibly less exact. Fluorine.—The fluorine was estimated by the Berzelian method. Though it is far from a good method, care and ex- perience enable one to obtain fairly reliable results. The ten- dency is toward too high results, because of the difficulty of freeing the calcium fluoride from last traces of alumina and silica; and a better method will probably show even less fluorine to be present in the tourmaline than the insignificant quantity now found. Ferrous owide.—Tourmaline, especially the varieties contain- ing lithia and iron, are decomposed by acids with extreme R. B. Riggs—Composition of Tourmaline. 37 difficulty. This fact together with the fact that the iron in tourmaline, possibly for some inherent organic reason, as the high and unstable degree of oxidation of the boric acid, oxidizes with unusual ease, has rendered the determination of the condi- tion of this constituent most troublesome On account of its refractory nature, usually not more than 0-2 grams of the finely ground mineral was taken for this determination. Several methods of decomposition were tried without any satisfactory results other than to lead to the conviction that the presence of ferrous iron in large amounts was doubtful, until the digestion of the mineral with hydrofluoric acid, in a sealed platinum ecru- cible over the direct flame, was resorted to with fairly satisfactory and conclusive results. ist. The mineral was digested with hydrofluoric and sul- phuric acids ina sealed platinum crucible in boiling water from one toseven days, a treatment which decomposes most minerals in the course of a few hours. In a few cases complete decom- position seemed to have been effected, in the greater number however it was at the best very incomplete. In no case was more than one per cent of ferrous oxide found, though between thirty and forty experiments were made, and some of the tour- maline analyzed contain as high as eleven per cent of the metal. These attempted determinations were made in a deep heavy platinum crucible of about 60 ¢.¢. capacity. This crucible is made with a flaring mouth into which fits a platinum head secured in place by a gallows screw clamp. Though the platinum joints are ground, arubber washer is inserted between the cap and the lip of the crucible to ensure tightness. Before sealing the cru- cible a little carbonate of ammonia is thrown in to expel the air. During the period of digestion the crucible is kept com- pletely immersed in water, so that itis hard to comprehend how the outside air can play any part in the oxidation of the iron. Iam accordingly tempted to think that we have here to deal with a very slow reduction of a highly oxidized condition of the boric acid at the expense of which there is a corresponding oxidation of the iron. Either the change goes on very slowly or the explanation proves too much. 2d. From 0:2 to 0°5 grams of the mineral were treated with sulphuric acid—4 parts acid to 1 of water—in sealed glass tubes, from one to four days, at temperatures varying from 150° ©. to 250° ©. Although the tubes were taken out of the bath frequently and shaken, decomposition, in none of the fifteen attempts, was more than partial. As even the best acid contains organic matter, sometimes in considerable quan- tities, a higher heat than 200° C. is likely to be attended by a reduction of the acid, thus vitiating the results. This was the method used by Mitscherlich (Journ. prakt. Chemie, Ixxxvi, 1) 92 38 RL. B. Riggs—Composition of Tourmaline. in establishing the fact that the iron in tourmaline is chiefly ferrous oxide. Rammelsberg, following in his steps, afterwards confirmed the results. But from what I can learn of their de- terminations they involved a correction which is of such a nature as to render the results worthless as quantitative results. The decomposition being invariably incomplete, the undecomposed material was removed from the glass tube, its amount determined, and a correction made accordingly. 3d. The mineral was also fused with bisulphate and with bi- fluoride of potash respectively in an atmosphere of carbon dioxide. Though decomposition was usually effected in a couple of hours, the iron was invariably all oxidized. A reduc- tion of the sulphuric acid may be the cause of the result when bisulphate of potash was used. No such explanation avails in the case of the bifiuoride fusion. 4th. Convinced, by the summations of some of the analyses, and by comparing the loss on ignition with the corresponding direct water determinations, that the iron in tourmaline must be there, in large part at least, in the ferrous condition, I finally heated the mineral with hydrofluoric and _ sulphuric acids in the closed platinum crucible over the direct flame, thus digesting at a moderately high temperature and.a correspond- ingly high pressure, and at the same time securing a constant agitation of the powdered mineral—a condition of vital im- portance. In these determinations a thin lead washer replaced the rubber. A half hour, with these conditions, usually suf- ficed to bring about complete decomposition. The crucible was cooled in an atmosphere of carbon dioxide and the iron determined in the ordinary way with a permanganate solution. Fair results were obtained, such as to indicate that the iron in tourmaline is there chiefly in the ferrous condition. Alkalies.—Several vain attempts were made to decompose the tourmaline with hydrofluoric and sulphuric acids. As show- ing the refractory nature of the mineral the following is a case in point: One gram of the pale green Auburn variety, after being ignited, was evaporated to dryness with 20 ¢.c. of hydroflu- oric acid five times, and yet left an insoluble residue of 0°473 grams. The Lawrence Smith method was finally adopted and with highly satisfactory results. The only precautions neces- sary are that the mineral be finely powdered and that the mix- ture with ammonium chloride and calcium carbonate be inti- mate, which latter condition is only to be secured by grinding the several ingredients together. When these conditions are what they should be, there is no trouble in bringing about complete decomposition in the course of an hour’s gentle igni- tion. After the alkalies have been leached out with water the residue should of course be treated with acid to test the com- R. B. Riggs—Composition of Tourmaline. 39 pleteness of the disintegration. In the case of the tourmalines, with their low silica percentages, the solution is usually com- plete if the decomposition has been complete. After the alkalies have been freed from the other bases by the usual well-known methods, though the greater part of the boric acid will have been driven off by the repeated evapora- tions, more or less may remain. This residual is removed by two or three evaporations with methyl alcohol. The sep- aration of lithia from the other alkalies was made by the Gooch method, i. e., by boiling the mixed chlorides in amyl alcohol, and the further separation of the potash and soda effected after the usual manner. Silica.—On the strength of the belief that tourmaline some- times contained fluorine in considerable amounts, the silica was at first estimated by precipitating it with carbonate of am- monia. When the bases, thrown out by this reagent, are so in excess of the silica as they are in tourmaline, its precipitation is quite easy and quantitative. Nevertheless, when the method was used of duplicate determinations, the higher was taken in the summation of the analysis. (Save where the silica is greatly in excess of the bases thrown down by ammonium ear- bonate, the addition of zinc or like compounds, as is commonly recommended, is wholly unnecessary. In fact, even in dealing with such minerals as the lepidolites, which contain about fifty per cent of silica and less than thirty of alumina, the addition of zine compounds gives no better results than can be obtained by simple evaporation with carbonate of ammonia, the evap- oration being repeated several times.) So soon as it became evident that the amount of fluorine, if present at all, wasso small that its influence in carrying off silica (the amount of silica carried off by fluorine on evap- orating a soda fusion with hydrochloric acid is but a small part of the tetrafluoride equivalent) could be neglected, the ordi- nary method of separation was employed. In all cases the silica was corrected by evaporation with hydrofluoric acid. Alumina.—The only point worthy of mention in this con- nection is the necessity of testing the alumina for the silica which it frequently contains. This is usually done by fusing the ignited oxides with bisulphate of potash. But when they amount to as much as they do in the tourmaline a carbonate of soda fusion works more satisfactorily. It can be continued longer and at a higher temperature. This fusion is readily con- verted into a sulphate fusion and the desired silica separation thus accomplished. As regards other determinations nothing in particular need be said. 40 RL. B. kiggs—Composition of Tourmaline. ANALYSES. Analyses have been made of material from the following lo- ealities: Auburn, Rumford, and Paris, Maine; Calhao, prov- ince of Minas Ger aes, Brazil; Dekalb, Gouverneur and Pierre- pont, N. Y.; Hamburg, N. J age Orford, N. H.; Monroe and Haddam, Ct.; Stony Point, N. C., and Nantic Gulf, Baffin’s Land. These represent well the variations in physical properties and chemical composition which characterize the different va- rieties of tourmaline. The results of these analyses are grouped for the sake of compactness. The tourmalines from Maine and Brazil are thrown together according to localities. Those from other localities are roughly grouped on the basis of their com- position. Maine.—These tourmalines oceur in veins of albitic granite, the chief constituents of which are quartz, albite and musco- vite, with lepidolite and beryl as important accessories. Auburn.—A. Colorless to pale green crystals, some of which were tinged pink and blue; infusible. G. 3-07. B. Light green fragile crystals, infusible. C. Dark green massive tour- maline, fuses with difficulty. 2). Massive black tourmaline, easily fusible. G. 3-19. A B C D a a SS ——S oO | if Il. 16 10%, Te Il. I. II. SiO. 38:14 — 38:00 37°85 — 37:80 36:26 — 36:98 34:99 — 34:87 Al,0s 39°60 ) 3773 | 36" a) 33°96 ) Fe,0;, °30 “42 | pone a FeO 1°38 Far *37-41°48 3°88 i 49: 42°54 7 yea °65-44°73 14:2 49:'76-49°79 TiOs none | none | idaed 2 P.O; trace trace trace trace MnO 1°38 “ill 172 06 CaO 43 “49 omy) OL MgO trace 04 16 1:01 is Oee M34 1:34 1:05 trace Na,O) 2:36 2°16 2°88 2-01 K,0 aN "62 “44 Tyee HO 416 4:06-4:26 4:18 4:16-4:20 4°05 4:00-4:11 3°62 3:°56-3°68 B.O; 10°25 10°15-10°34 10°55 9°94 9°83-10:04 9°63 9:44-9°82 F S62 em TO Go einer 71 — °80. none 100°23 100°39 100°28 100°00 less oxy. 26 26 “30 99°97 100°13 99°98 The material for the above analyses was received from Mr. N. H. Perry, of South Paris, Maine. Rumpore, A. Massive, rose-colored, infusible. G. 2°997. B._ Massive, dark green, fuses with difficulty. : eters Black Mi. Massive, black, powder bluish, easily usible, Lis Jy Riggs— Composition of Tourmaline. 41 A B Paris. —— (a ———____- ify Il. Ti II. Te IL. Si0. 38:07 — 38:02 3653 — 36°42 35°03 34°99-35:06 Al,O3 42°24 38°10 | 34°44 Fe,03 == | none Wols} FeO "26 { 42-44-42°64 6°43 12°10 P20; none | trace J trace MnO “39 CB 08 CaO 56 34 24. MgO OT none 1°81 Li.O 1°59 “95 ‘07 Na.O 2°18 2°86 2°03 KO “44 38 25 H.O 4:26 4:25-4:28 3°52 3:44-3:60 3°69 3:63-3:75 B.O3 9°99 .9°85-10°13 10°22 10°03-10°41 9°02 8:92-9:12 "28 16 none 100°29 . 99°81 99°89 Less oxygen ‘12 07 100°17 99:74 For the Rumford material Iam indebted to Mr. E. M. Bailey, of Andover, Maine. The Paris tourmaline was kindly furnished me out of the National Museum collection. In connection with the Maine tourmaline the following inter- esting alteration products were studied. A. An alteration from the light green Auburn (B) variety. .B. Flesh-colored alteration from the Rumford locality. C. An alteration from the Hebron rubellite. A B Cc SiO, — 53°03 43°90 Fe,0; — “bil. 58 FeO — — o25) MnO —_— trace 04 CaO — trace ‘41 MgO — trace 05 - Li,O 2°86 26 — Na.O 2°16 “54 1:05 K,0O 9°64 9°44 10°92 H,O0 — 4°80 4°25 B.0; trace trace trace — — trace ? none 100°25 100°16 While the light green Auburn tourmaline were mostly trans- lucent crystals, afew were found, which, having become partially opaque, had assumed a micaceous structure. With scant mate- rial but the above partial analysis was possible. The results indicate a change in the direction of lepidolite. The Rumford alteration product was examined microscopi- cally by Mr. J. 8. Diller, who observed as follows: “under the microscope it is seen to be composed of two minerals most 42 RR. B. Riggs—Composition of Tourmaline. thoroughly intermingled in nearly equal proportions. One of these minerals is micaceous in structure, with strong double refraction like damourite, which it closely resembles in general appearance. ‘The other mineral is clear, colorless and apparently monoclinic, with a rather low index of refraction and moderately intense double refraction.” While the Hebron rubellite alteration product retains its erystalline form, its material is altered into a softer mineral of an opaque talcose appearance. The analysis shows the change to be toward damourite (F. W. Clarke, this Journal, Nov., 1886), and not lepidolite as has been supposed in this case. Brazil, Calhas, Province of Minas Geraes. The association of these tourmalines I was unable to find out. From their compo- sition however it is probable that it does not differ greatly from that of the Maine varieties. The specimens analyzed were from the hands of Mr. G. F. Kunz. A. The pink, almost colorless center of crystals having a green border, infusible, G. 3-028. B. Pale green, like the border of B, infusible. @. Olive green, fusible in very thin splinters. . Black, in thin splin- ters a smoky blue green, fuses easily, G. 3°20. A B Cc D TG EN a oN 1 TI. 1s Il. I. II. 16 Il, lO Roe Oe Sel Do Stool encode SOLOW: 34:63 — 34:50 Al.O3 42°43 ) 39°65 38°13 32°70 Fe.O3 none |! 715 eSilk coil FeO 752 ( 42°94-43°08 2°29 ( 42:30-42°38 3:19 13.69 P.O; none J trace oT] none MuO ar) 1:47 2°22 12 CaO bi ‘49 38 Ys) MgO none none 04 2:13 Li.O 173 Neral 161 ‘08 Na.O 2°24 2°42 2°70 OWL K.0 48} 2) °28 "24 H,0 3°90 3:86-3:93 3°63 3°60-3°66 3°64 3°49 3°42-3°56 BO; 10°06 9:96-10°16 10°29 10°10-10°49 9°87 9:85-9°88 9:63 9°55-9°70 HY. trace. ? *32 — ‘Al CAN ie —— yn lh 06 — "10 99°66 100°06 99:53 99°52 Less oxygen als ‘06 02 99°93 99°47 99°50 Dekalb, St. Lawrence Co., N. Y. Colorless to light brown translucent crystals, in calcite, with quartz and titanic oxide in- clusions, easily fusible, G. 3-085. Gouverneur, St. Lawrence Co., N. Y. Brown, massive, asso- ciated with calcite. Easily fusible. Hamburg, N. J. Large cinnamon-brown crystals, associated _ with quartz and colorless mica in calcite, abounding in inclusions of small black scales of titanic oxide. Easily fusible. Rk. B. Riggs— Composition of Tourmaline. 43 Dekalb. Gouverneur. Hamburg. Se (aos — Sa oOo is II i II. Te Il. SiO. 36°88 37:39 37°33-37-45 35°25 Al.O3 28°87 PACTS) 28°49 Fe.03 — 10 none FeO “52 64 “86 TiO. se 4 1:19 65 iPOr undet. none trace MnO none none none CaO 3°70 2:78 5:09 MgO 14°53 14:09 14°58 SrO trace trace trace BaO none none none Li,O trace trace trace Na.O 139 Dsi2, "94. K,0 “18 ‘16 18 : H.O 3°56 3:55-3:57 S883) oH —3r89) 3°10 3:02-3°18 B.0; 10°58 10°46-10°70 10°73 =10°63-10°83 10°45 F “50 trace ? “18 100°83 100°42 100°37 Less oxygen 21 “33 100°62 100°04 For the Dekalb and Hamburg tourmaline I am greatly in- debted to Mr. G. F. Kunz. The Gouverneur material was from the National Museum collection. From the large amount of titanic oxide found in the Gouvern- eur specimen, it was feared that it might be there as an impurity. Mr. Diller kindly examined a section microscopically and found it, on the contrary, to be quite free from inclusions of any kind. Specimens, from other Gouverneur localities, viz: from the town of Gouverneur itself and from Reese’s farm, seven miles to the northward, were also found to contain the oxide in large amounts. Orford, N. H. Dark brown erystals in chloritic schist. Easily fusible. F?Donroe, Ct. Dark brown erystals in chloritic schist. Easily fusible. Oxford. Monroe. its II. Sid, 36°66 36°41 Al,O3 32°84 B12 Fe.0; none none FeO 2°50 3°80 TiO. O73 1°61 JB Oy none trace MnO trace trace CaO ; 1°35 ‘98 MgO 10°35 9°47 Sr,O trace trace BaO none none Li,O trace none Na.O 2°42 2°68 K,0 322, ‘ 21 HO 3378) 3°11=3:19 3:79 3:76-3°82 B.O; 10°07 9°86-10:28 9°65 9°57-9:73 i trace none 100°42 99°87 d+ Rh. B. Riggs—Composition of Tourmaline. The Orford material was received from Mr. C. H. Hitch- cock, the Monroe specimen came from the National Museum Collection. The schistose gangue, in which the tourmaline from Orford and Monroe are imbedded is of particular inter- est, and was studied microscopically as well as chemically, in the hope that it might throw light on the genetic relations of magnesian tourmaline. The microscopic work, which was of special importance was kindly undertaken by Mr. J. 8. Diller. The following are the results of partial chemical analysis :— Orford. Monroe. SiO. 27:18 43°30 Al,O3 33°10 27°44. CaO “9 1:96 MgO 28:09 19°22 Na,O undet. 1:47 K.O undet. 60 Ten. Tey (ts) 745 100°31 101°44 While Mr. Diller found the Orford matrix to be essentially chlorite, in agreement with the results of chemical analysis, the gangue rock of the Monroe tourmaline turned out to be particu- larly interesting. Of this Mr. Diller says, “this light gray glittering rock is composed chiefly of biotite, chlorite and a light colored mineral which may possibly be zoisite. The biotite is very dark and apparently uniaxial and negative, with all the other physical properties of the species. The chlorite is much paler than the biotite, and is of a greenish color. It is distinctly biaxial, with a small optic angle, and positive. The relation of the chlorite to the biotite is readily seen in the thin sections where it evidently is derived from the latter by a process of alteration. An interesting feature is that in the immediate vicinity of the imbedded tourmaline the biotite is all changed to chlorite, and is arranged with its foliae approximately perpendicular to the crystallographic planes of the tourmaline, against which it im- pinges. The chlorite completely envelopes the tourmaline and the other portions of the hand-specimen are made up chiefly of biotite and the zoisitic mineral, with a small proportion of chlorite. This variation in the mineralogical composition of the hand-specimen readily explains the discrepancy there at first appeared to be between the results of chemical analysis and my observations.” That the analysis represents a portion .of the rock rich in chlorite and poor in biotite, the high magnesia and low alkalies plainly show. The relation existing between the biotite, chlorite and tourmaline in this Monroe matrix is instructive, indicating, as suggested, the transition to be from the mica through the chlorite to the tourmaline. R. B. Riggs—Composition of Tourmaline. 45 Pierrepont, St. Lawrence Oo., N. Y. Perfect black erystals, in calcite, fuses easily. G. 3-08. Nantie Gulf, Cumberland, Baffin’s Land. A large black erystal, easily fusible. G. 3-095. Stony Point, Alexander Co., N.C. Perfect medium-sized black crystals, with implanted crystals of quartz; associated minerals chiefly quartz, muscovite, apatite, rutile, beryl and spodumene, fuses easily. G. 3:13. Haddam, Ct. Black erystals in quartz and feldspar, powder blue black, easily fusible. Pierrepont. Nantic Gulf. Stony Pt. Haddam, Cum Zs Nie aa Nan EFS a >) s 16 ld I. Il. Ty 10 il IL; SiO. 35°61 35°34 35°56 34:95 Al.O3 25°29 30°49 33°38 Sieh Fe.03 “44. none none “50 FeO 8:19 8°22 8°49 11°87 TiO. *5D “40 D5 oH P05 trace none ? trace MnO trace trace 04 09 CaO ool: 2°32 tate} “81 MgO 11:07 7:76 5°44. 4-45 SrO none trace none none BaO ? ? none none Li,O trace trace trace trace Na.O E52 1:76 2°16 2:22 KO *20 silty "24 “24. HO 3°34 3:30-3:37 3°60 3:53-3:67 3°63 3:57-3°69 3.62 3:°58-3°66 B03 10°15 10°00-10°31 10°45 10°30-10°60 10°40 9°92 9:74-10°10 F 27 none none none 99°93 100°49 100°42 100°35 Less oxygen, 11 99°82 Mr. W. EH. Hidden very kindly furnished the Stony Point material. For the other specimens [I am indebted to the National Museum collection. The gravity determinations of the Pierrepont, Stony Point and Nantic Gulf tourmaline were kindly made by Dr. William Hallock. From the above analyses it is at once apparent that we have three types to deal with, lithia, iron and magnesia tourmaline respectively, with an indefinite number of intermediate products. As an aid to comparison I have brought these results together in the following table, arranging them so as best to show how these types graduate from one into the other, beginning with the lithia. tourmaline and passing from them through the iron varieties to those of the purer magnesian type. The iron tour- maline appears to be the connecting link. LR. B. Liggs— Composition of Tourmaline. 46 V0-00L 8L- OT-€ 8I- V6: “Ty 89-F1 60-9 9uo0T “Ty go. 98- euou 67-85 GZ-G8 GFOL ~""" sinquey 69-001 0¢- 99-€ 8. 6&1 ‘4 €G-7T =04-€ ouou é GI: GG. euou 18-86 88-9 84-01 ~~~" ~~ q[eyed GP-OOL 2°44 €8-€ OL. 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Riggs—Composition of Tourmaline. 47 As the outcome of his work, Rammelsberg concludes that all tourmaline may be referred to the following silicate types: Rk’ SiO,, R’,SiO,, and R”,SiO,, in which R’=H, Li, Na and K, R’=Mg, Ca, Fe, and Mn and R’”= Al and B, making bo- ric acid and alumina equivalent. He groups them in two classes: I, iron-magnesian tourmaline, represented by the formula R’ SiO, R” SiO, mM sR SiO, (© ™) sRi7 SiO, R’”=B: 2A] and II, lithia tourmaline referred to the formula R’ SiO, R” SiO, ) where R’’=B: 3Al, mM) sR" SiO, L + ny sR’ SiO, with the following special formule : R’, R”, Al, B, Si, O,, for the more purely magnesian varieties ; R’,, R”, Al,, B,Si,, O,, for the purer iron varieties, and for the lithia tourmaline R’, Al,, B, Si, O,,, and other complications for those lithia varieties con- taining iron. Attention has been called to the weak points in Rammels- berg’s analyses; but, for the sake of emphasis, I refer again to his method of determining the water and what depends on it. He assumes that the fluorine is driven off quantitatively on ig- nitiop, carrying with it silicon as the tetrafluoride. This assumption is a questionable one. A half hour’s blasting would seem to be sufficient to drive off the water, but it was repeat- edly observed that where the tourmaline contained fluorine. further blasting, after the water was presumably all expelled, was invariably accompanied by a small loss. This after loss was probably fluorine in some of its silicon compounds, "as experiments made it clear that boric acid is driven off by no amount of blasting. While making this correction for flu- orine, the oxidation of the iron is wholly ignored. If anything was noticeable in the ignition of tourmaline it was the appar- ent ease with which the iron oxidized. In the above table the loss on ignition is given in many cases. Comparing this loss with the direct determinations of water, at the same time no- ting the amounts of iron contained in the tourmaline in ques- tion, one is forced to conclude that the oxidation of the iron plays an all-important role here, in diminishing the loss by ig- nition by the amount required to convert it into ferric oxide. If we take Rammelsberg’s ignition results* and make the more justifiable correction for the oxidation of the iron, setting aside the fluorine correction, we would have more concordant results to deal with ; results, moreover, which agree closely with the direct determinations of water. But if the percentages repre- * Pogg., xxx, 449; lxxxi, l. 48 R. B. Riggs—Composition of Tourmaline. senting water be low, those of boric acid, where estimated by difference, ought to be correspondingly high, and so they are in a few eases. In the greater number of analyses, however, they are unaccountably low, unless we suppose, as I am inclined to, that the silica determinations were high, representing in some eases, besides actual silica, more than a per cent of impu- rities.. If all this be true, in working out his ratios, Rammels- berg found in water and boric acid two variables instead of the two constants that they probably are, and one need not wonder that he found it difficult to discover unity in his analyses. It is scarcely necessary to say that certain constituents found in tourmaline are non-essential, but have been thrust upon them by their associates. The idea that a tourmaline must have its fluorine was long since exploded. If we study the essential constituents in the light of their molecular or atomic ratios, we will find some very interesting relations. The ratios of certain elements are constants in all varieties of tourmaline. Si: B: H:O=1:4:2:5°2. All the other constituents are variable and within rather indefinite limits. Considered individually they are enigmas. If, how- ever, the bases, including hydrogen, be reduced to a common univalent basis and be consolidated, the results fall into line with the above ratios. This reduction may be made in either one of two ways, and with almost equally good results. In the table of the ratios of constants given below it will be no- ticed that the oxygen ratio is invariably slightly in excess of the amount necessary to the silicon and boron even though we assume both the SiO, group as we certainly must, and the group BO, as is also necessary if we would give account for the oxygen. This small residual is to be disposed of. It can be done by postulating either an Al=O or the O-H group. Both hypotheses have been used in constructing the following table. RK’) is the univalent equivalent of the bases with the oxygen excess incorporated in an Al=O group, R(’) the univalent equivalent of the bases on the basis of an assumed O-H group. The table is given in full that the extent of the variations, from what seem to be simple ratios, may in no wise be con- cealed, as is often the case, when averages are given. The hy- drogen ratio, though already included in R, is given by itself, being one of the constants. For much the same reason the al- kali ratios are also given, although here the constancy would seem to be limited to a type. This at least appears to be true for the iron and lithia varieties. - R. B. Riggs— Composition of Tourmaline. 49 Si 13. ge RS EN ey MeO) 28) 0) 4 Be Tahoe UNE, Rumford A. - iL 46 4°48 5:01 5°18 14 "28 Bra Zilles 1 “47 4:45 5212 5:26 “70 coll Auburn A 1 46 4°43 4°83 5:10 42 "28 1sigvall 18) 1 “47 4°50 4:92 517 "66 soit Auburn B.___ 1 48 4-48 4°80 511 T1 30 lexervall Oh See iL 45 4°42 4°93 5°15 ‘66 "32 Rumford B..- i "48 4:44 4°95 5:20 64 30 Auburn C.__- 1 “46 4°50 4:99 5:20 74 28 aT See ] “45 4°47 5:09 5:21 “10 2 Auburn D, __ 1 “48 4-50 5:01 5:21 “10 e1'2 Brazile) ys a2 1 48 4°50 5:02 5yzill 68 olla Haddam: —2 22 i “50 4:51 5:00 5°24 69 “it? Nantic Gulf. _ 1 sil 4:52 5°00 5°25 68 2 Stony Pt.-__- 1 Obsyl 4:19 5°01 54]. 68 "10 Pierrepout. __ 1 51 4°52 4°17 5:13 63 09 Monroe. ____- 1 “46 4°43 4:89 5°12 69 15 Orfordsssses2 1 48 4:48 4:99 5°20 68 13 Gouverneur, . 1 50 4°51 4-73 5:10 68 10 Hamburg. __- 1 D1 4°50 5:08 5°30 “59 06 Mekal yess 11 50 4°51 5:08 5:29 66 08 1 NES By IRAE oY AAS a yOXD)'\ 8) RE = Except in two or three cases the ratios of Si: B: R(’):O ap- proximate closely 1:4:3:5. The oxygen, in excess of the amount exactly represented by the ratio (5), having been ab- sorbed in an Al=O group. These ratios give as a general tour- maline formula the simple boro-orthosilicate R,BO,2SiO,, which resolves itself into the graphic formula The R, includes the constant H=R¢ (Li, Na, K), varying be- tween the limits Ri and Rz, (Ca. Mg) varying from R, to R,, Fe varying from R, to R¢ and (Al, Al=O) varying from R, to R,. On the other hand the ratios Si: B. R(*):O are about as 1:4:10:5°20, which would give the equally simple general formula R,,BO,2Si0O,, where R,, includes the above constant and variables excepting that OH replaces the Al=O group and Al accordingly varies between the limits R, and R,. If we expand, in order to bring out the hydroxyl ratio, we have LSiOF 6BO. hE (OM) sir Beh O=1; 2£525:25. Between these two views there are at present no means at hand of deciding. Could we find out that the water is not all driven off at the same temperature or something of the kind, the knowledge would favor the latter assumption. Experiments to this end are desirable. But whichever pos- tulate we make, the following special formula may be taken as representing typical compounds of the three varieties: Am. Jour. Sci.—Tuirp SERIES, Vou. XXXV, No. 205.—Jan., 1888. 4 50 LR. B. Riggs—Composition of Tourmaline. I, Lithia tourmaline 12810,, 3B,0,, 4H,O, 8A1,0,, 2(NaLi),0. II. Iron tourmaline 12510,, 3B,O,, 4H,O, 7A1,0,, 4FeO, Na,O. III. Magnesian tourmaline 128i0,, 3B,0,, 4H,O, 5A10,, 28Me0, 2Na,0. Calculated. I TI. II. BIO; 11°00 10°18 10°90 SiO, 37-70 34:89 37°38 Al,O, 42°75 34°59 26°49 FeO 13°95 MeO —_—— 19°31 Li,O 157 Na,O 3°21 2°90 2°18 H,O Oiadalh 3°49 3°74 100°00 100°00 100:00 On comparing the theoretical composition of the above types with the results of analysis, they will be found to agree as closely as could be expected, at least in values of the constants. The boric acid found invariably falls short of the theory. This is to be expected. The analyses do not represent ideal com- pounds, but are made of material more or less impure and the case would be very exceptional where the impurity tended to raise and not lower the percentage of boric acid. In some of the above formulas the group BO, has been as- sumed because the oxygen ratio demanded it. As has already been suggested the ease with which the iron oxidizes and the mysterious manner in which this change takes place, under con- ditions when we would suppose it to be impossible, possibly point toward a higher degree of oxidation than the more com- mon B,O,. As the result of a slow molecular rearrangement the one is oxidized at the expense of the other. Such a change is, I believe, not without its analogies. Certain borates, where the assumption of an even higher oxide is thought necessary, on being heated give borates of a lower order. NVotes.—The question of color is an interesting one, particu- larly when the varying colors of the lithia tourmaline are concerned. For, while the color of the iron and magnesian varieties depends on the amount of iron present and ranges from the colorless Dekalb through all the shades of brown to the Pierrepont black, the lithia tourmaline, containing more or less manganese, give us the red, green and blue, as well as the color- less varieties, the shades of color not depending on the absolute amount of manganese present but rather on the ratios existing between that element and the iron. When the ratios of Mn: Fe approximate =1:1 we have the colorless, pink or very pale green tourmaline. An excess of manganese produces the red H. 8. Willkams—Devonian System in N. America. 51 varieties. On the other hand if the iron be in excess the result is the various shades of green and blue. As regards fusibility, the lithia tourmalines which are free from both iron and magnesia are infusible. The presence of either or both of these elements brings with it a degree of fusi- bility increasing with their increase till we find in those tourma: lines containing much of either or both constituents easily fusible minerals. The titanic oxide associated with the Hamburg and Dekalb tourmaline attracted special attention because of its form. Having been examined chemically it was studied microscopic- ally by Mr. J. S. Diller, who observed as follows: ‘“ The small iron black scales with a rather brilliant metallic luster are cleav- able into very thin folia, the thinnest of which, under the microscope, are perfectly opaque. In reflected light these lamellz show three systems of cleavage planes, traces of which, upon the plane of foliation, intersect at an angle of 60°. The cleavage planes make a large angle with the plane of foliation and it is evident that this mineral is rhombohedral in erystalli- zation. It is infusible on very thin edges and does not become magnetic when heated. By this means it is distinguished frofn hematite and ilmenite. From its physical properties alone I should conclude that it is a member of the ilmenite series rich in oxide of titanium. As analysis shows it to be essentially titanic oxide, it becomes of special interest. In the first place it is the extreme member of the ilmenite series and in the second place it is anew form of titanic oxide, which is thus shown to be tetramorphic.” Laboratory U.S. Geol. Suryey, Washington, August 31, 1887. Art. 1V.—On the different types of the Devonian System in North America ; by HENRY 8. WILLIAMS.* THE sections of the Devonian rocks in North America pre- sent at least four distinct types of stratigraphy in their out- crops in different parts of the continent. The four areas blend somewhat at their borders, but in their central sections are very distinct. The four areas may be called the (1) Kastern Border Area, including the outerops of Gaspé, New Brunswick, Maine, and other places in Northern New England ; * Read at the New York meeting of the American Association for the Advance- ment of Science, August, 1887, and constituting a part of a preliminary report on the Devonian to the American Committee of the International Congress of Geolo- gists. 52 H..S. Williams—Different types of the (2) The Lustern Continental Area, including the New York and Appalachian tracts as far south as West Virginia, and extending northwestward into Canada West and Michigan ; (3) The Znterior Continental Area, typically seen in Iowa and Missouri, extending into Illinois and Indiana, and probably northward toward the valley of the Mackenzie River; and (4) The Western Continental Area, best known through Hague and Walcott’s studies of the Eureka, Nevada, sections. Each of these four areas presents sections of the Devonian, which in all the details of their stratigraphical, lithological and paleontological composition are different from each other. Tue Eastern Borper AREA. The typical eastern border section, as seen at Gaspé, is a heavy series of arenaceous shales, sandstones and conglomer- ates, gray, drab and red in color, of some 7,000 feet thickness. It lies upon 2,000 feet of limestone, which holds in the upper part fossils of upper Silurian age. These are regarded by Billings as of Helderberg types. The first thousand feet of the sandstone shows a rich flora, and, by some traces of inver- tebrate fossils, is known to date back as early as the age of the Oriskany sandstone. The first 5,000 feet of the sandstone rep- resents the interval from the top of the Silurian to the top of the Chemung series of the New York section, and the terminal 2,000 feet may represent the Catskill series of New York. (See Logan’s Report upon the Gaspé section in “ Geology of Canada,” 1868, p. 390, ete.) The greater part of this section contains very few fossils, and these are mainly plant remains. In the continuation of the Gaspé sandstones on the Bay de Chaleur the lower and upper beds, as I am informed by Sir William Dawson, are not only distinguished by characteristic plants but also by a rich fish fauna resembling that of Scotland, and divisible into a lower zone with Cephalaspis, Coccosteus, ete., and an upper with Pterichthys. On tracing the outcrops westward across Maine and Northern New England, the coral- bearing limestones of the lower Devonian appear, indicating a changed condition of the seas on approaching the old Archean axis on the westward, but the outcrops, as well as the identity of the fossils, are too indefinite to give a clear idea of the rela- tion of this border region to the better known sections south of the Adirondacks and farther west in New York State. Tur EAasTtTERN CONTINENTAL AREA. The second area, the eastern continental, is represented typ- ically in New York State. From there it has been traced downward along the Appalachians as far as to West Virginia (the Tennessee section assuming a closer relation to the interior Devonian System in North America. 53 area), and northwestward in Ohiv, Canada West and Michigan. On the western side of the Cincinnati axis the section is inter- mediate, but presents closer relations with those of the interior than with the typical New York section. In New York there is a full series of temporary stages of deposition each having its characteristic lithological compo- sition and each holding its distinctive fauna. The lower Hel- derberg limestones were followed, in this area, by a deposit of coarse sand which is thicker and more prominent in the eastern and southeastern part of the region, there attaining several hundred feet in thickness, but thins out toward the northwest, and fails altogether, both in the extreme southwestern and in the extreme northwestern extension of the area. This is the Oriskany sandstone, marked by a few large and well-defined Brachiopods. The Oriskany stage is generally more or less calcareous, and runs up into caleareous shales and grits along the northeastern border of the area. These latter are the Cauda-galli and Schoharie grits of the New York section. They are followed above by the Onondaga and Corniferous limestones, averaging less than a hundred feet in thickness, but reaching three hundred feet thickness, or more, in some parts of New York and in Michigan. In this eastern continental area there was evidently some relationship between the sandy deposits beginning in the Oris- kany and the calcareous deposits typically represented in the Onondaga and Corniferous limestones; for we find in the northwestern part of the area the sandstones thinning out to almost nothing, while the limestones reach their greatest thick- ness, and in the eastern and more southern parts of the area the sandstones reach their greatest thickness, while the lime- stone dwindles and in some parts has not been distinguished at all. The limestone is rich in corals, and in some layers, has abundant Brachiopods; the latter are types of wide geographi- eal distribution, and, in the more common forms, such as Strophomena rhombordalis and Atrypa reticularis, are species of long geological range. Some of the corals, too, have a long range ip the western continental section, appearing in the upper part of the Nevada limestone, according to Mr. Walcott. In New York the next lithological stage of the Devonian is a series of shales, often beginning and terminating in black and sometimes partly calcareous shales ; but in the central part of the section, gray, soft argillaceous shales, temporarily calcareous in places, and holding a rich and abundant fauna, constitute the Hamilton stage. The Hamilton also shows tendency to be more calcareous westward and more arenaceous in the eastern out- crops, and the sandstones and arenaceous shales are thicker and predominate in the Pennsylvania, Maryland and Virginia sec- 54 A. §. Williams—Different types of the tions, while the argillaceous and calcareous shales are more con- spicuous in New York, Ohio, Canada West and Michigan. A thousand feet may be taken as an average for the thickness, in- eluding the two terminal black shales, though some of the Appa- lachian sections double this thickness. In our accepted classifi- cation the upper, Genesee black shale is grouped with the Ham- ilton, but, as I have shown elsewhere, there are good reasons for drawing the distinctive line, separating middle and upper De- vonian, below rather than above the Genesee shale. Above the Hamilton stage a period of deposition of arena- ceous shales and sandstones prevailed all over this eastern area, called the “Chemung Period” by Dana, and divided into the Portage and Chemung stages. The deposits attain a thickness of two or three thousand feet in New York and Northern Pennsylvania, and farther south are represented by 5,000 feet of sandy deposits, coarser toward the top, and with occasional gravel conglomerates. This series of deposits is characteristic of the eastern area, and is not recognized in the central or west- ern areas. It is linked by its flora with the eastern border sec- tions, and by its fauna is recognized as intimately associated with the upper Devonian deposits of North Devonshire in England. The faunas of the upper Devonian change rapidly in com- position on passing westward from the Appalachian ridges, and the pure Chemung type is scarcely recognized west of western New York and Pennsylvania, although some of its species are seen in the lowa and Nevada sections. Passing into Ohio, Canada West and Michigan, the upper part of the Devonian assumes a distinct type, which is more closely allied with that of the Indiana and Illinois sections. It appears to be a prev- alence of the conditions expressed in the Genesee shales and associated Portage shales and sandstones of New York, with the failure of the Chemung rocks and fauna, running up into shales and sandstones of the Waverly and closing with con- glomerates. The more eastern sections, after the Hamil- ton, run up into sandstones, red and gray shales, sand- stones of considerable thickness, and conglomerates, and present no trace of any marine fauna intermediate between the Chemung and the Carboniferous. As we approach the Ohio border going westward the Chemung fauna also fails, and the Waverly follows the Hamilton with only the fauna of the black shales intervening. In the eastern part of New York, Pennsylvania and south- ward, the coarse sands and conglomerates with red and green shales, prevail after the Hamilton stage, reaching a thickness of 6,000 or 7,000 feet, and then the Chemung fauna is sparse and confined to the lower strata. This red shale and sandstone Devonian System in North America. 55 type is called the “ Catskill group” in New York, the “ Cadent series” of the Pennsylvania nomenclature. In the eastern Appalachian area this same lithological type of rocks continues all the way upward to the coal measures; green and red shales, sandstones and conglomerates, and occasionally thin beds of limestone, but with no trace of the marine faunas which char- acterize the interval in Ohio, Indiana, and, particularly, in the interior continental area. In Pennsylvania these rocks have been ealled ‘“ Vespertine Series,’ “‘ Umbral Series,” and “ Seral Conglomerates’’ by the first survey, and “ Pocono Sandstone and Conglomerate,” ‘“‘ Mauch Chunck Red shale,” and “ Potts- ville Conglomerate,’ by the second survey, and in central and eastern Pennsylvania they together reach a maximum thickness of nearly 5,000 feet. These peculiarities, however, do not ex- tend westward of Pennsylvania and New York. Before reach- ing that line, in fact, the red shales have nearly disappeared from the total section, and as the Chemung fauna disappears upward, the new Waverly fauna comes in, but only in the bor- der regions between the two areas, are found sections in which both the Chemung and the higher Waverly faunas appear. This Waverly fauna is a transitional fauna and is, in the east, gener- ally associated with the higher Sub-carboniferous marine faunas, and in sections in which the next lower fauna is that of the Hamilton or Middle Devonian. In the Eureka faunas described by Mr. Walcott, representatives of it are found in the upper Devonian shales (“‘ White Pine Shales”) associated with traces of the upper Devonian faunas of the east. THE CENTRAL CONTINENTAL AREA. The central continental area is typically represented in Iowa, Illinois and Missouri, and reaches into Indiana, Kentucky and Tennessee, and possibly far north into British America. Its prevailing characteristics are calcareous shales and lime- stones, with some arenaceous admixture at the eastern and south- ern extremities, terminating in black shales, and rarely exceeding two or three hundred feet in thickness. On the north, east - and south-east borders of the area the black shale termination is a conspicuous feature, but in the more central portion, in Towa and Missouri, the black shale is either entirely wanting or but slightly represented. In Illinois and Indiana the black shale reaches a thickness of one hundred feet or more, and is immediately followed by the shales and limestone of the Kinderhook, or Knobstone group holding a fauna closely allied with that of the Waverly group of Ohio. East of the Cincinnati axis the black shales are first thin; they thicken on going eastward, and distinctly represent the upper Devonian of Western New York. Including all that 56 Fl. S. Williams—Different types of the is now rated as above the Hamilton shales and below the Bed- ford shales this upper Devonian of Eastern Ohio is from 400 to 2,000 feet in thickness, thinning westward (See Professor Or- ton’s Preliminary Report on Petroleum and Gas, 1887, p. 26). When we reach the central part of the interior area we find the Devonian represented by limestones running up into fine argillaceous shales, resting on upper Silurian limestones which in numerous places are of Niagara age and, in the southern border of the region, are more or less siliceous, and hold fossils of the later Silurian time, as in the Delthyris shales of Missouri which are, doubtless, as late as Lower Helderberg time. This central area lacks the black shale and runs up immediately into Sub-carboniferous limestones, calcareous shales and sandstones, and the total representatives of the Devonian are scarcely 200 feet thick. i THE WESTERN DEVONIAN AREA. I take the Nevada section of the Eureka district as typical, since this has been carefully developed by the labors of Hague and Walcott. (See Walcott’s Monograph, Paleontology of the Eureka district, U. S. Geol. Survey, 1884). The peculiarities of this section are as follows: Lying unconformably upon a thick series of limestone beds, representing the Trenton and, at the top, the Niagara of eastern sections, comes the Vevada Limestone, 6,000 feet thick, indis- tinctly bedded and siliceous below, and becoming massive toward the top with intercalated beds of shale and quartzite. The same fauna runs from bottom to top, but with some change in part of the species. In the lower 500 feet the fauna is dis- tinctly lower Devonian, and in the terminal 500 feet it is as distinctly allied with the upper Devonian of the east. Through- out there are found species which in the typical eastern sections are restricted to particular zones. In its species it shows closer relationship with the lowa Devonian than with the more eastern faunas, containing two species (see p. 265) that have been found far to the north in the Mackenzie River Basin, i. e. Orthis McFarlini and Rhynchonella castanea, (N. 67° 15’ long. 126° W.) Overlying this limestone is the White Pine Shale, a black shale, estimated at 2,000 feet in thickness, running into red and brownish sandstones and arenaceous shales, with some plant remains and a sparse fragmentary fauna which closely re- sembles in general character the fauna of the similar upper Devonian black shales of the eastern continental area. In these western sections there is a remarkable difference in the range and habit of species. ‘Some species,” as Mr. C. D. Walcott has shown, “have reversed their relative position in the group as they have been known heretofore, and others have a \ Devonian System in North America. 57 greater vertical range.” (Pal. of the Eureka District p. 4). Some cases mentioned by Mr. Waleott are Orthis Tulliensis at the top, Orthis impressa at the base, and several Corniferous corals at the upper horizon (see pp. 4 and 5, etc). It is also noticed that the faunas in the higher shales show combinations of Devonian and Carboniferous types (White Pine Shales), but a careful study of the species reveals the characteristic changes of the general fauna that are seen in the eastern sections. For instance, the new type of Brachiopods belonging to the genus Productus (called Productella in the New York Re- ports) begins in this western section with certain small forms typical of the lower and middle Devonian of the east, and it is only in the upper horizons that the larger Chemung types of Productus appear. The same thing is seen in the changes in the types of Spirifera; the characteristic upper Devonian Sp. disjuncta appears ouly in the upper part of the section as in the east. The peculiarities of this western section in its Paleontol- ogy, are most readily explained by the assumption, supported also by other facts, that throughout the whole age the deposits of this area were made in a wide, open ocean, with islands, perhaps, but with no great masses of land to disturb the general uniformity of the conditions of life. The central area was, doubtless, at considerable distance from land but in no great depth of depression. The eastern conti- nental area from Michigan around through Canada, New York and down the Appalachians, must have been during the Devo- nian age, near enough to shores for the faunas, as well as the nature of the deposits, to be affected by the ocean currents, and to feél strongly the effects of relatively small amounts of change of level between land and water. Here the faunas are both more local and more limited in geologic range, changing more suddenly and fully in their combinations and species. The conditions of the eastern border were those of rough and tem- pestuous coasts. CONCLUSIONS. There are thus, Ist, a northeastern border area, mainly com- posed of coarse, arenaceous deposits, thick, and with little to distinguish it into subordinate zones. 2d. An eastern continental area, with sandstones, limestones, shales and conglomerates alternating with each other, and pre- senting a rich and varied series of faunas, marking a consider- able number of distinct zones which follow in a constant order. 3d. A central continental area, mainly limestone and soft argillo-calcareous shales, and, compared with the more eastern sections, very thin, and presenting a fauna which represents the 58 H. S. Williams—Different types of the whole eastern Devonian and is plainly a sequent to an under- lying upper Silurian fauna. It is followed by a Carbonif- erous fauna to which it is generically closely related, and about its border is terminated by a black shale. 4th. A western area represented by a massive thick series of limestones followed by black shales, not separated into distinct faunas, but carrying a common fauna showing but slight change from bottom to top. With all these great contrasts in lithological, stratigraphi- cal and paleontological characters the evidence is satisfactory that the several sections are representatives of the same geo- logical age; that, taken as wholes, they do not represent parts, the one taking the place of an interval in the other, but they cover approximately the same interval, and probably rep- resent approximately the depositions of the same length of geological time. They are bound together, and their relationship certified to by the fossils they contain. The relationship is recognized in the combination of species to form faunas and in the vari- etal modification of species, as well asin the identity of the species themselves. We cannot find stronger contrasts across the Atlantic eastward than are found across the continent westward. The principles which the American geologist is required to apply in discussing the gevlogy of his own do- main are no less broad than those which the International Congress meets with when it attempts to unify nomenclature for all the world. Wherever unification is practicable in Amer- ica it is practicable for all the world, and where America finds unification a cumberance it is useless for an International Con- gress to attempt it. What is there in the Devonian system, as represented in North America, which demands uniformity of nomenclature, and wherein will attempts at uniformity in nomenclature either strain or misrepresent the facts ? ist. It is perfectly clear to a paleontologist studying the faunas and floras, that the system under consideration, in each of the so dissimilar types, is the representative of the Devonian system of Great Britain, Belgium, Germany and Russia, in all the central features of its marine and brackish invertebrate, and vertebrate faunas, and in its floras. That the name Devo- nian, as the first name used, should be applied to this system of rocks, we see no reason for dispute. 2d. In all the sections, in so far as they exhibit it, the order of sequence in the modification of faunas is the same, and this sequence as presented in foreign sections is found to follow the same order, wherever species are identical, or are closely allied varieties of the same type; their place of dominance in Devonian System mn North America. 59 the series is the same for each section, but the range may vary; in one area species may be restricted in range; in an- other, species may range through a long series of deposits. In other words, species which are found to have a world-wide distribution, although in one area they may be restricted to a particular stage of the Devonian, are likely to have a long geo- logical range in other areas, not less than from bottom to top of some complete Devonian sections. Buta particular combi- nation of species, forming a characteristic fauna of a special stage In one area, occurs at the same relative position in any other area in which it appears. Such faunas are, however, actually more or less local, and, as far as the Devonian is con- cerned, it is not practicable to form more than three subdivi- sions of the Devonian to which to apply universally a uniform name. These three, in their general typical faunas, can be rec- ognized (so far as they are present) in the different areas of America and Europe, the lower, typically seen in the Cornifer- ous limestone of New York; the middle, represented in the Hamilton of New York; the upper, represented in the Che- mung fauna of New York. Any attempt to unify in the finer details is useless for America, and, of course, would be useless if attempted for all countries. 3d. In the sections of America alone there is found nothing in lithological composition or sequence which is uniform for the several areas. In seeking uniformity of nomenclature the study of the American Devonian leads to the following conclusions : (1) That uniformity is desirable in the names and prominent distinctive biological characters of the so-called systems. (2) That valuable results may be reached by a discussion, on the part of those acquainted with the same system in the dif- ferent parts of the world, as to the best biological criteria for marking the boundaries of the systems. (3) That while uniformity is possible in subdividing a sys- tem into parts, the number of such parts, and the characters distinguishing them, must_be determined after a wide, compre- hensive and minute study of their biological characters. (4) That preliminary work in classifying rocks should not seek uniformity, but should adopt local nomenclature, and that nomenclature based upon an exhaustive comparison of repre- sentative sections can alone reach a uniformity that will be of permanent value. 60 C8. Hastings—Double Refraction in Iceland Spar. Art. V.—On the law of Double Refraction in Iceland Spar ; i by CHARLES 8S. HASTINGS. THE law of double refraction in uniaxial crystals, first dis- covered by Huyghens, was supposed for a time to be defini- tively established by Fresnel’s deriving it from principles of molecular mechanics. It was soon recognized, however, that a fundamental hypothesis in his reasoning does not bear eriti- cal inspection; namely, that the elastic forces brought into play by distortions due to the passage of waves are the same » in kind as those produced by the displacement of a single par- ticle. In short, Fresnel assumed that the velocity of a light wave is independent of the direction of propagation and de- pends only upon the direction of vibration. There have been many notable efforts to get rid of this difficulty in the theory of double refraction by a general treatment. Cauchy, Mac Cullagh, Neumann and Green are those whose names are most closely connected with the interesting history of investigation in this field of mathematical physics. All of these investiga- tions have the feature in common, that the natural interpreta- tion of the equations makes the direction of vibration in plane polarized light lie in the plane of polarization. To adapt the solutions to the contrary assumption, which is almost certainly the only one which ean be reconciled to the known phenomena of optics, requires the most artificial restrictions in the rela- tions of the constants involved. By such forced imterpreta- tions of formulas having a large number of constants, it 1s possible to derive a law for double refraction, even in Ice- land spar, which does not differ from Huyghens’s construe- tion by an amount discoverable by observation; but an agree- ment between observation and theory extorted in this way can- not be regarded as satisfactory. Intimately bound up with this question of double refrac- tion is the question as to whether the differing velocities of light in vacuum and in a dense medium are due to differing densities or differing rigidities. Of these two views, equally probable @ priori, only the first can possibly be brought into agreement with the observed phenomena of reflection. But in the case of a velocity of propagation dependent on the di- rection of wave-motion, which is the case of double refract- ing media, the difficulty is to conceive of a density as dependent upon direction. Rankine made the ingenious suggestion that this difficulty might be avoided by assuming that the mole- cules of a crystalline solid move in a frictionless fluid, and thus that their effective masses might depend upon the direc- tion of motion. The special interest of this view from our C. 8. Hastings—Double Refraction in Iceland Spar. 61 standpoint is that it led Stokes to the first careful investigation of the accuracy of Huyghens’s construction.* In these investigations Professor Stokes found that the error in the construction could hardly exceed a unit in the fourth place of decimals, which was quite sufficient to disprove Ran- kine’s hypothesis. This study, the details of which have not been published, remains unexcelled to the present time ; for the investigations since made by Abria, Glazebrook and Kohl- rausch, whether by the prism method or by total reflection, do not present a closer accordance between theory and observa- tion. The results of earlier observers, cited in most treatises on double refraction, are all of quite inferior accuracy. Of all these investigations, Glazebrook’s, given in the Trans. Roy. Soe., vol. clxxi, 1880, is the most extensive. His method was to measure the deviations produced by four different prisms, so cut from the same piece of Iceland spar that the di- rections of the propagation of the light varied from an angle of — 3° to + 94° to the erystalline axis, the relation of this axis for each prism to its faces being determined by reference to planes of cleavage. The observations were made with con- siderable accuracy, indicating a probable error in the deduced indices of refraction considerably less than fifty units in the sixth place of decimals. The reductions, however, show a sys- tematic deviation from Huyghens’s construction, varying from 100 to 200 in the sixth decimal in the three hydrogen lines ob- served—the wave-surface for the more refrangible ray deviat- ing most widely. This result would be of great theoretical interest if the values derived from observation were not vitiated by an important oversight in the details of the experi- ment, which the author himself points out. In view of this source of error the conclusion from the investigation is, that Huyghens’s construction is true within the limit of error of these observations. Briefly, then, the state of the case is this. The law of double refraction in Iceland spar as given by Huyghens is known to be true to within about one part in ten thousand, but no rea- son, dependent on the theories of elasticity, can be assigned why it should be as accurate as this, or how much more ac- curate we may expect to find it. The labor of testing the law to the last degree of refinement possible with modern instru- mental means seems well worth while; for, except its sim- plicity, there is no reason in the world why it should not break down just at the limit assigned by Stokes’s observations. Iam quite willing to admit, also, that the systematic deviations of Glazebrook’s observations, so near the limit of magnitude set * Proceedings of the Royal Society, June, 1872; quoted by Sir Wm. Thomson in his Baltimore Lectures, p. 273. 62 OC. S. Hastings—Double Refraction im Iceland Spar. by Stokes, and so difficult to explain by any plausible hypothe- sis as to their cause, suggested a not too remote probability that they indicated a physical reality. With these ends in view, all methods except those based upon prismatic refraction were practically excluded. Again, since it is impossible to get cleavage faces which admit of very accurate determinations of their angles of inclination, e. g., to within a second of are, it seemed necessary to arrange the experiment so as to be independent of such accurate determinations. The method chosen, then, was to measure the various angles in- volved in an equilateral prism of Iceland spar in which one face was normal to the crystalline axis, the other two as nearly equally inclined to the axis as possible, and all three refracting edges as perfectly at right angles to the axis as practicable. Such a prism restricts the range of wave velocities which can be observed, but on the other hand, it enables us to find the direction of the crystalline axis from the observations them- selves by mere considerations of symmetry, wholly independ- ently of all assumptions of the law of double refraction. (2) Description of Prism. Since the accuracy of a determination of a refractive index depends largely on the character of the prism used, and espe- cially in this case of extraordinary refraction, it may be worth . while to describe the method employed to secure satisfactory results. After selecting a good block of spar, a wooden model of the largest prism of desired orientation which could be obtained from the block was made. As this model represented the cleavage faces as well as the prism faces, it served as a guide as to how far any process of grinding should be carried. One of the obtuse trihedral angles was ground down, so that when the block rested upon this ground surface under a fixed tel- escope nearly perpendicular to it, the images of a distant object reflected by the three opposite cleavage faces could be brought to the crosswires of the telescope by merely rotating the block on the ground surface. This admitted of securing a face, P in the accompanying figure, very nearly perpendicular to the crystalline axis. The limit of accuracy was restricted only by the character of the reflection from the cleavage faces. The — size of the face was determined by reference to the model. The next step was the formation of the surface, dbefg of the figure, to serve as a base for the prism and a rough guide for the other two faces of the prism. It was ground perpendicular to P, and, by a process similar to that used in fixing the direction of P, equally inclined to the cleavage planes ab Q C. S. Hastings—Double Refraction in Iceland Spar. 638 and 6c@Y. Then # was ground so that it made equal angles with the cleavage surfaces a7) Y and adg, and an angle of 60° with P. As it was desirable to make this last angle tol- erably accurate in order to eliminate all errors of the circle in a determi- nation of the refracting angle, or, in other words, so that a repetition of the angle three times would bring the cir- cle back to the same position within the range of the reading microscopes, the surface P was polished suffi- ciently to yield a good reflection, and then the angle at > was adjusted until it was equal to that of a glass prism known to be accurately 60°. @ was determined in a precisely similar way. The three surfaces were then polished to as close approximations to planes as pos- sible. In this process most interesting differences in the phys- ieal properties of the surfaces were found, as might have been expected. /¢ worked almost as readily as glass, except that its departure from flatness tended toward cylindrical surfaces in- stead of spherical. It was not difficult to make P flat, but the slightest carelessness in handling would produce tetrahedral pits init. The surface QY, being inclined only 15° to the di- rection of cleavage, gave by far the most trouble, because it did not seem possible to get it very smooth by grinding. After carrying this process to its limit of accuracy, determined more, perhaps, by the extraordinary thermal properties of the material, than by purely technical difficulties in working, the faces were cut away until only circular areas were left on the three prism faces. These round faces were then modified, by methods which would only have an interest for the practical optician, until they were optically flat; that is, until their departures from their average planes was not more than a tenth of a wave- length of light. The test of flatness was the colors produced when white light was reflected nearly normally from the sur- face brought closely in contact with a surface of glass known to be plane. The diameters of the surfaces, in order of letter- ing, were: 2°83 em., 2°38 cm. and 2.6) em. (8) Spectrometer. The instrument with which the measures of the various an- gles were made has some features peculiar to it. The circle is of glass, 8 inches in diameter, and divided to single degrees, except in the case of the first degree, and three others separated 64 CO. S. Hastings—Double Refraction in Iceland Spar. from it and each other by quadrants, which are subdivided to tenths of a degree. The observing telescope may be moved independently or clamped to the circle; it is checked in its rotation only by the collimating telescope. It is obvious that by this construction it is always possible to measure an angle so that one end of the are shall be at a degree mark and the other end fall within a subdivided degree; hence both ends of the are are within the range of the reading microscopes. The great and manifest advantage of this construction is that every angle can be accurately measured after determining the abso- lute place of only 396 lines or 198 diameters. The reading microscopes have micrometer screws of 80 threads to the inch, with heads divided into 100 parts, one rev- olution of the screw being equal to one minute of are. The magnifying power is 220 diameters, doubtless unnecessarily _ high, but not found inconvenient, and a much lower power would have necessitated a notable change in the design, either finer micrometer screws or longer microscopes with correspond- ingly higher table and telescope carrier. The probable error of a single setting of the microscope was found to be less than 0”:3, or less than half a division of the micrometer head. The errors of the circle were determined by means of two auxiliary microscopes clamped to the base-plate of the instru- ment at opposite sides. By bisections and trisections the ab- solute position was determined of each diameter at multiples of 5° from the initial diameter, to within a probable error of less than 1”. As practically every such interval was involved in the observations several times, equations of condition were formed as checks upon the results; if a discrepancy as great as 1” was found the intervals were re-measured. A determination of any angle was thus reduced to a maximum of five repeti- tions, whence the true angle could be found, and, incidentally, the corrections of four other ares. As an illustration of the precision of the method, I may state that in the only case where a suspicion of the accepted value led to a complete redetermi- nation of all the constants involved, the correction deduced differed only 0’"1 from the former one. The origin of the suspicion was afterwards found to be a false temperature cor- rection. This determination of the errors of the circle was the most laborious part of the whole investigation. (4) Angles of prism. The angles measured were those between the normals to the ~ faces P and Y, YQ and #, R and P, which were made with all attainable accuracy ; those between the normal to P, and the normals to its three adjacent cleavage faces; the normal angle C. S. Hastings—Double Refraction in Iceland Spar. 65 between / and the narrow cleavage face at b; and finally, the normal angles between the cleavage faces ab @ and be Q respectively. The precision of all the measures involving re- flection from a surface of cleavage is of course much inferior to those made upon the polished” surfaces. The first group gives the refracting angles, and the others only serve to deter- mine the direction of the crystalline axis, a datum not used in the final reduction but useful as a check on the’ work. The general method of determining these angles was as fol- lows: The telescope replaced the fixed collimator which was removed. By means of a plate of plane parallel glass and a guast collimating eyepiece* the axis of the telescope was ren- dered strictly perpendicular to the axis of rotation of the instrument. The focal adjustment of the telescope could be made at the same time with great precision : magnifying power used, twenty diameters. Following this adjustment the glass plate was replaced by the prism, which was so adjusted that the line of collimation fell close to the center of each face when in position for observation: That this condition, a most im- portant one, was fulfilled, was determined by removing the ocular and looking at the prism through the telescope tube. Taste I1.—Angles of prism =« = 60. PQ PR QR Obs. t Red. Obs. t Red. Obs. t Red. 417205 |17-2 |+17285 ||—27516]17-°0: |—2/-519 || +17330 /16°5 | 417-303 949 \1T-1 280 *492 117-0 519 298 116-5 303 273 |17-0 276 “521 |17-0 519 -254 |16°6 293 407 |19°8 “421 “B21 |19°55 394 067 |19°2 046 “421 |20°0 “412 [-652]|19°65 Hr eas 1141 |19-25 041 -432 |20°0 “412 “418 |19°75 384 0°908 |19°55 1013 391 |20°0 “412 "350 |20°7 338 895 |21°0 0-875 -469 |20°1 ‘417 315 |21-0 323 883. 121-0 “875 453 |20-0 “412 295 |21°5 299 “858 |21°5 "828 390 |20-0 412 235 |21°3 308 836 21:1 “866 475 |20°1 “A1T 350 21-1 318 eB 21:1 866 514 [20-1 “417 354 |21°1 318 B73 121-2 “856 ‘470 |21:0 “457 *306 |21:2 *313 741 |22°5 732 484 |21-2 ‘466 231 |20°8 333 703 |22°6 123 A81 |21:1 462 "QA |22°9 230 || +0°695 |22°8 +0°704 453 |21°7 ‘A89 ‘QAT 123-0 2.25 e “427 |21°4 ARO) | =O) IAN 193- ni) -99'5 “A783 |21°6 “485 "519 |21°6 “485 “445 |21°6 485 ‘A435 |21°8 “494 “511 |23°0 “548 ‘511 |23°0 548 4+1 °528 123-0 }+1 548 * This is described in the paper ‘‘ On the influence of temperature on the opti- cal constants of glass.” This Jour., II], vol. xv, p. 271. Am. Jour. Sci1.—THIRD Surizs, Vot. XXXV, No. 205.—JAn., 1888, i) 66 CO. S. Hastings—Double Refraction in Iceland Spar. In the case of the prism angles each was repeated three times, whence, since they were all quite close to 60°, not only were all errors of graduation eliminated, but the absolute values of the instrumental arcs 120° and 240° determined with great accuracy. ‘The influence of temperature on the magnitudes of the angles becomes evident even in comparatively rude observa- tions. Table I gives ali the measures of these angles. Of course the angles given are the supplements of those directly observed ; they are also corrected for cirele errors. Following the column containing the observed angle is given the temper- ature of the prism, and then the value reduced to a tempera- ture of 20° C. The method by which the last column was cal- culated will be given farther on. The observation of PR enclosed in brackets is rejected. Two or three others might have been rejected without chang- ing the results except to give them smaller probable errors. Tn order to find the values of the angles a standard tempera- ture (20° C.) was chosen as the standard, observation equations of the form =m+n (t—20), whence normal equations of the form Za’, m+ 248. r— Loe. M=0, a8. m+ =>6’.n—=268. M=0, gave the means of finding m and. The values of the coefii- cients of the normal equations are as follows : xa? Las =p? SaM =P. M PQ 24 SP7/ 72°67 34°514 22°647 PR 16 79 64:6 —37'570 -—15°588 QR 15 2°4 66°42 14°324 — 3°980 The observed values of a from these equations are : For PQ Oe nl 412-0" 006--0':0454 (t—20°) PR 59 57', 628-0’ 009--0" 0489 (¢— 20°) QR 60-0’. 970. 0':008 —0':0950 (¢— 20°) The probable errors of a single observation of an angle were found to be 0'-028, 0°035 and 0’:032, respectively, and the probable errors of the coefficients of the terms containing the temperature 0/0035, 0':0045 and 0’-0039, respectively. The probable error of 2" for a single observation seems large, con- sidering the refinement of the method used, and indeed it would be fora glass prism ; but regarding the enormous change from temperature and the extreme difficulty of determining that of the prism, it must, I think, be regarded as satisfactory. These constants derived directly from observation are subject to certain geometrical conditions which will modify them very slightly and reduce the probable errors. As it was C. 8. Hastings—Double Refraction in Iceland Spar. 6% found,. in the course of the observations, that the normal to any one face is inclined only 12’ to the plane fixed by the . other two normals, we have— 22 => OY . nn, = — 7N,. But as observed, =a = 180° 0-010 + 0':013. n,+n,= — n, + 00007 + 0':006. Adjusting the observed values in accordance with the equa- _tions of condition we have finally : Grog = 60° 1’ 247-59 + 07°29, Opp = 59° 57! 37"-42 + 0"°43. == 6.009 0154 08 = Opes n, = — 5”68 +019. The value of », enables us to find at once the difference in the principal coefficients of thermal expansion, as well as the variations of the angles of the rhombohedron. By an obvious relation, if a, and a, are the coefticients in the axial direction and at right angles to it respectively, we deduce a,-—a@, = 10-6(31°+ 1°). The best value known is that of Fizeau, which is | 10-6 (31-6). But the relations of immediate value to us are those of the temperature variations of the angles between the normals of P and an adjacent cleavage face, of /¢ and the cleavage face }, and of the two faces ab @ and bc@Q. They are, in the order named, if % is the measured angle JALS} ; ap = -+ 0°:056 = — 0103 = — 0085 (5) Position of crystalline axis. The measures upon which this constant depends are subject to large errors on account of the imperfect reflections from the cleavage faces, especially from the edge 6, which is only 1™ wide and gives two images. The values given below are re- duced to a temperature of 20° C. Angle. = 44° 39'12 + 0°50. P(a6Q) = 44° 3657 + 0°045. P(adg) = 44° 37/05 + 0°120. Ré = 75° 25’ 00+ 0°160. (abQ) (6cQ) = 105° 4"°88, 68 CO. S. Hastings—Double Refraction in Iceland Spar. Of these the first and fourth, giving them equal weights, yield Pb = 44° 38'-26 which, with the second and third, give 44° 37-99 as the angle between the crystalline axis and the normal to a cleavage plane. The last of the measured angles implies 44° 36/°70 for the angle between the axis and the normal to a cleavage face. This value, however, rests upon two observations only and cannot therefore be regarded as of great weight. We may, perhaps, attribute to it a weight 4 that of the value de- rived from the other measures, whence the accepted value becomes 44° 37'°19, This value gives, for the direction of the axis drawn from P inward, an inclination ‘ €=1'4"1 from the normal to P towards Q, and Te" ae i. e., 12” below the refracting plane of the prism QR; they - ean hardly be in error as much as 15”. It is perhaps worth noting that the accepted value 44° 37-19 gives 105° 5’-07 for the dihedral obtuse angle of the rhombo- hedron at 20° C., which is practically the value accepted by mineralogists. (6) Angles of deviation. Minimum angles of deviation were determined in each ease ; there are thus two angles for each prism-angle. The line pointed upon was the more refrangible component of the D line of the solar spectrum, except in the case of the extraor- dinary image by the faces QR, of which the dispersion was too small to admit of easy separation, and, by mistake, in four pointings on the double deviations for the ordinary image by the same refracting angle when D, was observed on one side. Care was taken to adjust the collimator, telescope and prism, so that the axial ray passed through the center of the prism in both positions for minimum deviation, i. e., right and left. The lines of collimation were made at right angles to the axis of the circle and to the refracting faces by means of the plane giass plate and the collimating eyepiece. For observing the spectrum a magnifying power of 31 was employed. Table C. 8. Hastings—Double Refraction in Iceland Spar. 69 II contains all the measures for the ordinary ray, then the tem- perature (¢), the barometric height (Bar.), and the angle cor- rected to 30 inches barometric height. In the table, the mis- takes mentioned, and which were confined to the four preced- ing the last, are corrected by adding 0’-285, the measured dis- tance between D, and D.,. Taste IIl.—Double angles of deviation for ordinary ray D,,. aA, = 104° PQ PR QR Obs. %|-Bar:|" (Cor: Obs. t | Bar.| Cor. Obs: t |Bar.| Cor. + 87-454 20:3 3129-85| + 8/-423)|—37-772)19°-4/30°1 |—37-752\14+7 “658/16 7|30°1| + 77678 "472 |20°4|29- ee 44] *701/19°8/30°1 “681 *546|)17°1/30°1 566 “497 |20°7/29°8 “466 ‘661)19°9|30°1 641 °531/17-2/30°1 Sayam b *559/20°3/30°1 *539) 336 17-9 30°1 *356 *560/20°2/30°1 540 134)18°8}30°1 "154 *552/20°6/30°1 *532)| + 77:085|19-0/30°1 "106 *618/19°8)29°75 669] + 67983) 19°1/30°1| + 77-003 479/20°3/29-75 *530]/’ -92.1)19°7/30°1)] + 67-941 —3/-455)/20°4/29°75| — 37-506 “914 20°1)30°1 934 "799 20°1|/30°1 *819 *839)/20°2/30°1 *859 | "743 20°6|30°1 “700 + 67680 20°6'30°1' + 67-762 The observations for PR and QR were reduced by form- ing observation equations of the type M = m-+n(t—20). and, the temperature correction for PQ being assumed as the same as that for PR, the reduced values for J are, for PQ 52° 4! a 20 + 0"-54-+6"-72(¢— 20) PR bile 58' "52 + 0"18-+6 -72(¢—20) Oly =) 522 3/ 26" 10--0"°30—7""17(é— 20) Tas_eE III. 2M = c PQ 94° PR 94° QR 72° Obs. ¢ |Bar.| Cor. Obs. | ¢ |Bar.| Cor. |; Obs. ¢ |Bar.| Cor. eee | +17°983|20°7 29°85| + 77-955) |— 27518)19°6/30°1 | —27537) | +.3/-474/16°8/30°1| + 37489 87:045/20°7/29°85) 87-0177 *555/19°7/30-1 ‘B74 *454/16°9/30°1 “469 101) 20°8)29°85 073 454/19°9/30-1 | ‘472 456)17:4/3071 ‘471 “110; 20°9)29°85 082 *430)/19°9/30°1 448 °360/17°7/30°1 “375 + 8/-088|21°0/29°85/ + 87-060 ‘436/20°5|30'1 | 454) °356/18-9}30°1 ‘371 391/20°6/30°1 409 °307/19°0/30°1 322 429/20°0/29°75 “475 °331/19°2/30°1 346 —2/-361|20:1 29°75 —2/-407 *309}19°4/30°1 324 Ber [37-495]]20-1/30-1] ._-- °294)20°4/30°1 309 | °277|20°5|30-71 392 | °251)/20°6/30°1| +37:266 [37-634 ]!20°6!30-1 Soh 70 C.S8. Hastings—Double Refraction in Iceland Spar. Table III gives the double angles of deviation as measured for the extraordinary ray for each refracting angle. As has already been stated, the deviation is that belonging to D,, ex- cept in the case of the edge QR, where, on account of the small dispersion, the sodium line was set upon as a single line. As before, the observations enclosed in brackets are rejected. These were reduced in quite the same way as were the devia- tions for the ordinary ray, with the following resulting values for 4,: PQ 47° 3! 58"°23+-0"'39-+43"'60(¢—20°) PR 46° 58’ 45"°694-0"°244 3" 60(¢— 20°) QR 36° uy 39"°21-4-0"'21 — 17°58(¢—20°) In order to reduce the angle of deviation for QR to what it should be for D,, the angular distance between D, and D, for dA¢ aA, for this region of the spectrum, was taken as an additive cor- rection. ‘The value of the correction was found to be 8”°85, whence the deviation for the extraordinary ray D, for QR be- comes the ordinary ray was determined, and half its product by 36° i 43”-06+0"'21 (7) Principal indices of refraction. The crystalline axis has been found to make an angle of less than 1’ with the plane bisecting the refracting angle QR; hence we may apply the ordinary formula connecting the index of refraction with the angles of minimum deviation and refrac- tion, namely, sin an =~ os sin — 2 The resulting indices will be the principal indices for calcite at. a temperature of 20° C. The for PQ 1°658393+-2 PR 1°658387+-2 QR 1°658387+2 1°658389+1°2 The single value of yp, is 1°486450-+1°4 (8) Zest of Huyghens’s Law. C. 8. Hastings—Double Refraction in Iceland Spar. 1 observed extraordinary deviations by the refracting angles PQ and PR. First, we have the well known law, uennae COSie~ | SINS Liv, nN tay where yp, and yw, are the reciprocals of the principal wave ve- locities as before, and y’, is the reciprocal of the velocity of the extraordinary wave whose normal makes an angle @ with the crystalline axis. This enables us to compute y’., knowing ¢@. Second, we have the series of relations given by Professor Stokes (British Association Report, 1862), wr sing: |) sind oe sing! ~ gine’ P+p=Ata ces ROS = BN) +a tg iz 9 ei tg 9 CO rami? where yg # are the angles of incidence and emergence respec- tively, and @’ ¢’ the angles which the wave normal makes with the faces of the prism within it. These relations enable us to derive a value for y’, from the observations, perfectly independ- ently of any assumption as to the law of double refraction if we know either g or ¢. They afford a much readier test than that of calculating the deviations for an assumed law. ‘We do not, it is true, know the values of g for the extra- ordinary refractions by PQ and Ph, but as the prism was always set for minimum deviation it is easy to find these values, either by taking advantage of the fact that Huyghens’s law is already known to be nearly true, whence the angle of incidence for minimum deviation can be calculated, or, more simply, from the relation sing __ sine sing’ sin” and the two purely geometrical equations which follow this equation above. It is found by trial that for PQ, the light being incident on Q the value of ~ which satisfies the condition is 50° 25’, and for PR and incidence on R, the value of ¢ is 50° 21’. A small change in these angles does not alter the difference between the observed and calculated values of p’., which affords the test of the law. _The substitution of these values in the equation of Stokes gives— ! Me PQ 160611416 PR —_—-1'606103-+1°6 te es a 72 CO. 8. Hastings—Double Refraction in Iceland Spar. It remains to calculate the values of wv’, from Huyghens’s theory from the known values of g’ or ¢’ and the assumed direction of the crystalline axis defined by & above, since 7 is so small that it can be regarded as zero. The measured value of € is 1’ 4” with a considerable uncertainty, but I find that a value of 1’ 6’ will make the differences between obser- vation and theory symmetrical. With this value we have Ss) pe’, [eale.] PQ 31° 19’ 45-68 1°606109-+E1°8 PR 31 19 58 °34 1°606099-—-1°8 where the probable errors are calculated without disregarding the fact that we have imposed the arbitrary condition that the differences shall be symmetrical. The difference between a measured index of refraction in Iceland spar at an angle of 30° with the crystalline axis, and the index calculated from Huyghens’s law and the measured principal indices of refraction, thus appears to be 4°5 units in the sixth place decimals, while, assuming the truth of the law we ought to expect, from the probable errors of the quantities involved, a difference of +2°4, only about half as great. There is, however, one source of constant error in the observations which has not been alluded to, namely, the fact that the temperatures: of the prism were measured by a different thermometer in the case of the angles of the prism and the angles of deviation. In the former a rather insensi- tive thermometer divided to single degrees and estimated to tenths was used, and in the latter a very sensitive thermometer divided to half-degrees. By reference to my notes I find that the two systems of temperatures are connected only by an eye comparison on a single day, s0, although I believe that the error of comparison cannot be much over one tenth of a degree, it is by no means certain, or even improbable, that an error of this magnitude may enter. It was not thought in that stage of the investigation that such an error was of any significance. Unfortunately one of the thermometers has since been broken so that a direct comparison is out of the question. The observations of the ordinary indices contain implicitly, however, the desired correction as appears from the following reasoning :— Let dt be the excess of the reading of the first thermometer, used in the prism-angle measures, over that of the second ; then its most probable value is that which renders the probable error of the mean value of , a minimum, when the three observed values are regarded as independently determined magnitudes. Chemistry and Physics. 73 au, ap, da Thus ode eam 25°68 for QR =——4:22°84 for PQ and PR, the first differential coefficient being derived from the formula from which yp, is calculated, and the second is given on p. 66. From these and the values of 4, on p. 70 treated as independ- ent determinations, we have 23°9 dt=—2 WE) of pee OE 11:9 dt=—4, whence dt= — 0°:084-+-0'082. From this it is obvious that such a correction is required. Supposing, then, that the angles of the prism given above correspond to a temperature of 19°-916 C. instead of 20° C. we have the following definitive values for the quantities involved: a Ay, Ay Mo Owe | 247830 eh 2s 01-20) 472 3105826) 16d 83a92 PR 59 57 87°66 51 58 11°52 46 58 45°69 1°658387 QR 60 0 57°60 2 tora 2 Onl Olirs OF ME a3 OG 1°658389 whence [j= 1°658389 MM, 1°486452 ihe je’, [calc. | PQ 1°606113 1°606110 PR 1°606102 1°606100. The conclusion is, that Huyghens’s law is probably true to less than one part.in five hundred thousand, and, consequently, that there is no known method by which we can hope to discover an error in it by observation alone. New Haven, Nov., 1887. SCIENTIFIC INTELLIGENCE. I. Cuemistry AND Prysics. 1. On the Decomposition of the Hydrides of the Halogens by Light in presence of Oxygen.—Some time ago it was observed by Backelandt and by McLeod that hydrogen chloride gas, when exposed to the combined action of atmospheric oxygen and sun- light, was partially decomposed, chlorine being evolved. In order to determine the conditions under which this change is effected, Ricuarpson has made a series of experiments on hydro- gen chloride, bromide and iodide gases, (1) when the gaseous mixture exposed to the sunlight is moist; and (2) when it is dry. 74 , Scientific Intelligence. In the former case, oxygen was present (a) in only sufficient quantity to oxidize’ the hydrogen, or (b) in large excess. Bulbs of about 300 ¢.¢. capacity were filled with the gaseous mixture and sealed. The hydrogen chloride gas was prepared from sodium chloride by the action of pure sulphuric acid. The oxygen was freed from any chlorine it might contain by passing it through sodium hydrate. After exposure to the light, the bulbs were opened under water and the chlorine compounds thus absorbed. The resulting solution, made up to known volume, was divided into two equal parts. In the first the total chlorine was deter- mined and in the second the free chlorine. In the first experi- ment the moist gases were mixed in the ratio of 4 vols. hydrogen chloride and 1 vol. oxygen, and the bulb was exposed to sunlight for 24 days. The free chlorine formed amounted to 0°34 per cent. In the second experiment, in which the oxygen was 8 vols. to four _ of hydrogen chloride and in which the exposure was 21 days, 73°81 per cent of chlorine was evolved, the mixture in the bulb being distinctly greenish after five days. In the third and fourth experiments, the gases were mixed in the same proportion and exposed to sunlight for 57 days. Notable quantities of hypo- chlorous oxide or other oxide of chlorine were produced. In the fifth experiment the gases were both carefully dried over phos- phoric oxide. After 27 days exposure in one case and 63 days in another, not a trace of free chlorine could be detected. The hy- drogen chloride was then saturated with moisture and mixed with dry oxygen. But an exposure to sunlight of 60 days failed to produce any free chlorine. Hence, a mixture of hydrogen chloride and oxygen is perfectly stable in sunlight not only when dry, but even in presence of aqueous vapor, provided liquid water be absent. Similar experiments were then made with hydrogen bromide. When the gases were moist and the oxygen was that required to oxidize the hydrogen, an exposure of 46 days pro- duced 0°64 per cent of free bromine. When, however, the oxy- gen was in large excess, 7°73 per cent of bromine was set free in the same time. In case the gases were dry, no bromine was evolved. In the experiments with hydrogen iodide, 94°31 per cent of free iodine was produced in 20 days when the oxygen was not in excess and 96°08 per cent when an excess of oxygen was used. Even dry mixtures of these gases were found to be decom- posed by sunlight. Hence, the author concludes: Ist, The sta- bility of the moist hydrides of chlorine, bromine and iodine is de- pendent on the mass of oxygen present, in excess of that required for their complete decomposition. 2d, Dry or partially dry hy- drogen chloride and bromide are completely stable, even when mixed with a large excess of oxygen. 3d, Dry hydrogen iodide is decomposed in presence of oxygen.—/J. Chem. Soc., li, 801- 806, November, 1887. G. F. B. 2. On the Influence of Liquid water in promoting the Decom- position of Hydrogen chloride by Sunlight in presence of Oxy- gen.—In a paper immediately following the one above mentioned, Chemistry and Physics. 75 ARMSTRONG discusses the apparently anomalous result that water in the liquid state is necessary to the reaction just described. He regards the interaction in this case as only another instance showing the general fact that interactions which are commonly assumed to occur between two substances, are possible more fre- quently than not, only in presence of a third substance (which he calls a catalyst). The case in question is parallel to that of the oxidation of sulphur dioxide investigated by Dixon. ‘In gas- eous mixtures chemical change appears so take place only when a comparatively high electro-motive force, or its equivalent, is employed; one sufficient to produce disruptive discharge being | usually required. Regarding the interaction as a case of electro- lysis, a gaseous mixture of HCl, O, and OH, therefore might be expected to prove insensitive to light. But an aqueous solution of hydrogen chloride is one of the best of liquid conductors and it is easy, therefore, to understand that a relatively small electro- motive force should suffice to electrolyze a liquid system of the same three elements.”—2J. Chem. Soc., li, 806-807. G. F. B. 3. On the Concentration of Solutions by Gravity.—Experi- ment teaches that a homogeneous solution left to itself at con- stant temperature, preserves sensibly its homogeneity. Gouy and CHAPERON have examined this question mathematically in order to see how far this result, taking gravity into the account, is in ac- cordance with thermodynamic principles. And they find that under these conditions, the permanent state of a solution is not one of abso- lute homogeneity but that the density of the liquid increases from the surface downward according to a determinate law; so that in time the primitive homogeneity of a solution will be destroyed by gravity, and a new state of equilibrium will be established within it. To show that the principle of Carnot is in contradic- tion with the hypothesis of absolute homogeneity in the case of a heavy solution in the permanent state, the authors suppose a per- fectly homogeneous solution placed in a vessel of height H. Let a very small portion of this liquid of volume V, at its upper surface, be supposed temporarily isolated from the remainder of the solution. If the weight da of the solvent pass by distillation from this isolated portion to the rest of the liquid at constant temperature, evidently no work will be expended. Suppose now that, since the weight of the solvent dw has gone from this isolated portion to the rest of the liquid, the density of this portion increases in con- sequence by an amount dD, its volume will diminish by dV ; and now if by reason of this increased density, this portion sinks to the bottom of the vessel, it will do a positive amount of work equal to H (V—dV) dD. If after this we suppose the homogen- eity of the solution to be re-established by diffusion the cycle will be closed, the total work done in the cycle will be zero and hence 2D must be zero. It is not possible therefore for a solution to be perfectly homogeneous in the permanent state unless its den- sity does not vary for an infinitely small variation of the concen- tration. But if, on the contrary, the solution is not homogeneous, 76 Scientific Intelligence. its density increasing gradually downward, the isolated portion above mentioned will be in equilibrium in the liquid when it has fallen through a distance dH; so that the positive work done in this case will be an infinitesimal of the second order and therefore negligible. From a formula deduced in the paper, the authors have calculated the amount of substance at the top and at the bottom of a column 100 meters high, for four different solutions. For cadmium iodide at top 0166, at bottom 0°153; a difference of 0°013. For sodium nitrate 0°20 and 0°196; a difference of 0-004. For common salt 0°11 and 0°1095; a difference of 0°C005. And for sugar 0°55 and 0°546; a difference of 0:004. These differences, though apparently too small to have any practical value, have a very considerable theoretical importance.— 3 nye S06. Van XXX: -° FEBRUARY, 1888. Established by BENJAMIN SILLIMAN in 1818. THE AMERICAN JOURNAL OF SCIENCE. EDITORS JAMES D. ann EDWARD §. DANA. ASSOCIATE EDITORS Prorussors ASA GRAY, JOSIAH P. COOKE, anp JOHN TROWBRIDGE, or CamBringE, Prorsssors H. A. NEWTON anp A. E. VERRILL, or New Haven, Prorrssorn GEORGE F. BARKER, oF PHILADELPHIA. THIRD SERIES. VOL. XXXV.—[WHOLE NUMBER, OXXXV.1 No. 206—FEBRUARY, 1888. WITH PLATE Il. NEW HAVEN, CONN.: J. D. & E. 8. DANA. 1888. TUTTLE, MOREHOUSE & TAYLOR, PRINTERS, 371 STATE STREET. Published monthly. Six dollars per year (postage prepaid). $6.40 to foreign sub- geribers of countries in the Postal Union. 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Published WEEKLY at $8.00 a year, free of postage; or for $10.50, THE Livine AGE and any one of the American $4 Monthlies (or Harper’s Weekly or Bazar) will be sent for a year, postpaid; or, for $9.50, THe Livinc AGe and the © St. Nicholas or Scribner's Magazine. Address LITTELL & CO., Boston. ME yr A Wil CH, YY/AK£ cM), THE AMERICAN JOURNAL OF SCIENCE [THIRD SERIES.] Oe by T. C. MENDENHALL.* SEISMOLOGY as a science, or at least as an observational and experimental science, may be said to be the product of the past three or four decades. It is true that before as well as during this period some important applications of the statistical method of investigation were made and the distribution of earthquakes in time and space was thoroughly studied. These investigations are of really high value, although they have generally resulted in the overthrow of certain hypotheses which were constantly appearing as to the correlation of these displays of seismic en- ergy with other natural phenomena ; so that while it may be said that little is yet known concerning the real nature and ori- gin of earthquakes, much useful work has been done in the way of elimination and possibly a reduction of the number of un- known quantities involved. The new phase which the science has assumed may perhaps be fitly described by saying that the modern seismologist studies an earthquake, rather than earthquakes. In fact this is one of a considerable group of problems primarily geological in their nature to which, in recent years dynamical principles and phys- ical methods have been applied. The knowledge of first im- * Read at the meeting of the National Academy of Sciences at New York Noy. 8th,.1887. Am. Jour. Scil.—THIRD SurRizs, VoL. XXXV, No. 206.—FEB., 1888. 6 98 T. C. Mendenhall—Seismoscopes and portance in regard to an earthquake is the knowledge of the nature and location of its origin and it is generally admitted that this can be obtained only through the study of individual instances. The natural method is to proceed from the known effect to the unknown cause, and for a time progress in seis- mology consisted largely in painstaking and laborious investi- gations of the destructive effects of earthquakes from which it was believed a knowledge of their ultimate origin might be deduced. Little in the way of experiment had been attempted and nothing was known of the really complex motion of the earth-particle when subjected to the influence of an earthquake wave. False assumptions were made with regard to this motion and erroneous and perplexing conclusions resulted. The great work of Mallet on the Neapolitan Earthquake, although of - much importance in its day, and always a monument to his in- dustry and devotion to the science, can not now be considered as of any great value as a solution of the problems involved. The importance of earthquake measurements by means of specially constructed instruments was recognized by Mallet, however, and he undertook the design and construction of such instruments at an early date. The problem seemed at first easy, but investigation proved it to be of considerable difficulty. In a general review of the state of the science in his report to the British Association in 1858 Mallet says,* “twelve vears ago the construction of seismometric instruments appeared a compara- tively easy matter. It is only at a very recent period that experiments and observations as to the actual phenomena, the velocity and direction of the shock, etc., have begun to show the real difficulties of the subject.” But even at this time Mallet failed to recognize the true nature of the disturbance produced by an earthquake, and the several seismometers which he de- vised, and which will be found described in the report already referred to, are practically of no value. One of them, which was extremely elaborate in its construction, he considered com- petent to furnish, from a single station, all of the elements necessary for the determination of the seismic focus. Another, the arrangement of two rows of cylinders of varying diame- ters in lines at right angles to each other, is probably the most widely known of all earthquake machines as it is described in many encyclopeedic articles and treatises on Geology in which the subject is discussed. It may be said, however, that a more useless device has never been proposed. A notable advance in our knowledge of the subject and par- ticularly of instrumental Seismology has been made during the last: half dozen years and it must be largely attributed to the * On the Facts and Theory of Earthquake Phenomena—Report of the British Association, 1858. ; Seismological Investigations. 99 organization and active operations of the Seismological Society of Japan. Earthquakes are there so frequent that a rare oppor- tunity for their study is offered. A few foreigners temporarily residing in the country, together with a number of native scholars, joined in the prosecution of seismic investigations and in the establishment of the Society. Its published transactions, already filling ten volumes, contain nearly all of seismology that is in advance of the old methods. Progress has been made mostly in the direction of improvement in seismographs, and is, in a great degree, due to better methods for securing the very desirable “ steady point” and to arecognition of correct dynam- ical principles in the construction of the instruments. The well known horizontal pendulum or “bracket” seis- mographs of Ewing,* Gray,t Milne and others, have greatly increased our facilities for research and, in fact, have afforded about the only fairly reliable information concerning the real movement of the earth-particle. Notwithstanding the comparative infrequency of earthquakes in the United States, many advantages for their study are offered here. Among others may be mentioned the following: the great extent of country which could be brought under one sys- tem of observations ;—a generally intelligent population, fur- nishing a corps of willing and reliable observers ;—the extensive system of telegraph lines; and, perhaps superior to every other, the wide distribution and almost universal use of “standard time” throughout the country. In consideration of these ad- vantages and of the fact that certain portions of the country appear to be subject to occasional seismic disturbances, it has seemed desirable that an extended and well planned series of observations should be undertaken, and that seismology should not be in the future, as it has been in the past, a somewhat neglected science. Among American geologists especially, there has always been great interest in the subject, and a good deal has been written concerning geological theories of earthquakes. Rockwoodt has done excellent service in his publication of frequent catalogues of earthquakes in America, together with such information re- garding them as could be incidentally gathered. But the first important step towards an elaborate and systematic study of earthquakes was taken a few years ago by the Director of the U.S. Geological Survey in establishing what has been known as the “ Karthquake Commission.” The work of this body, during its existence, consisted mainly in the discussion of methods of observation, together with the preliminary arrange- * Trans. Seis. Society of Japan, vol. ii. + Trans. Seis. Society of Japan, vol. iii. ¢ This Journal, from 1872 to the present time. 100 T. C. Mendenhall—Seismoscopes and ment of a plan of attack and the selection of the most desirable regions for the inauguration of the work. A scale of intensities was adopted and a series of questions formulated which. were printed in the form of circulars for distribution among the in- telligent observers of any disturbance. These circulars were subsequently made use of by Captain Dutton, who had the gen- eral direction of the work, and considerable information con- cerning several earthquakes has been obtained. ‘The Charleston earthquake of 1886, renewed and greatly increased the interest in the problem. It was thoroughly investigated by Dutton and Hayden and their report* upon it, presented to the National Academy of Sciences in April, 1887, is of great value. As complete, perhaps, as was possible under the circumstances, it serves to emphasize the necessity for the use of seismic appa- ratus, and causes extreme regret that instruments had not been previously perfected and put in operation. I think it can be said that America has made at least one really valuable contribution to the Science of Seismology. I refer to the approximate determination of the velocity with which earthquake waves are transmitted through the crust of the earth. The unexampled opportunities offered in the explo- sions at Hell Gate and Flood Rockt were utilized for this pur- pose, with the unexpected and surprising result of a rate of transmission vastly greater than that previously obtained by Kuropean and Oriental Seismologists, and generally accepted as fairly accurate. The reduction of fairly accurate time observa- tions made on the occasion of the Charleston Earthquake,t served to confirm this conclusion and a speed of several thou- sands instead of a few hundreds of meters per second must now be admitted. Although these results are more nearly in accord with the theory of wave transmission, future determinations of velocity will be awaited with great interest, and all processes employed must be carefully scrutinized. Before considering a plan for the inauguration and main- tenance of an extensive series of seisomological observations, it will be well to inquire what knowledge is most desirable in the interests of geological investigation. This is a question — for geologists to answer; but I venture the assertion that in the present state of our knowledge of seismology, it is most desirable, in the case of any given earthquake, to be able to fix the seismic vertical, or the epicentrum; to ascertain the depth at which the initial disturbance occurred; and to measure the velocity with which the resulting waves are transmitted. If these can be accurately determined for differ- ent earthquakes, under varying conditions, some light may be * Science, May 20th, 1887. + Science, Jan. 8th, 1886. t Science, May 20th, 1887; see also this Journal, Jan., 1888, pp. 1-15. Seismological Lwestigations. 101. thrown upon their ultimate origin and the magnitude of the energy involved, while the study of velocities of transmission, co-seismal and iso-seismal lines, may afford valuable informa- tion concerning the nature and condition of the rocks within the disturbed area.. Admitting the greater importance of a knowledge of these facts it follows that time measurements should first receive attention, and that the seismic chrono- graph is the instrument to be used. The seismograph or seismometer is cous spehingetly for the purpose of recording or measuring the actual motion of that part of the earth to which the instrument is attached during the transit of one or many waves. In reality this motion is extremely complex. Undoubtedly the emerging wave is modified very greatly in its character by the lack of homogeneity in the material through which it last travels, as well as by the fact that this material differs immensely in elasticity and density from that in which it has in the main existed. For this reason it is believed that however accurately the motion may be resolved into three components at right angles to each other by a perfectly operating seismograph, but little information would be afforded as to the position of the origin, or the amplitude of vibration and amount of accelera- tion of any point in the earth, other than that at which the instrument is located. It is clear, however, that while these considerations may seriously affect. the integrity of the record of a seismograph, they will have little influence upon the actual transmissive time, that is to say, while the character of a wave may be greatly altered upon emergence into a non-compact- ed, non-homogeneous material, the time of its arrival at a given point cannot be greatly alter ed, even if its velocity in this material is much less or greater than the mean, for the reason that it is subjected to this modifying influence for a comparatively brief period. It is true that the seismograph, in addition to register- ing the motion of the earth particle, may and generally does record the epoch of the passage of a wave, and it affords the advantage of distinguishing one wave from ‘another. If only very short distances are used for the determination of veloci- ties this would be of decided value, were it not that experi- ence* seems to prove that what is the maximum wave at one point may not be the maximum at other points very near, so that it is by no means certain that a particular wave can be identified at different stations, even if they are not widely separated. These considerations, together with the very great expense of seismographic equipment and the greater difficulty of maintaining them in constant working order in a country where earthquakes are infrequent, compel the admission that * Milne, in Trans. Seis. Soc. of Japan, vol. x. -102 T. C. Mendenhall—Seismoscopes and the simple seismoscope, with a time-taking attachment, is far more likely to furnish valuable information. SEISMOSCOPES. A good seismoscope should possess some if not all of the following characteristics :— It should be simple, inexpensive and not liable to become inoperative through long periods of rest ; It should be capable of adjustment to varying degrees of sensitiveness ; The adjustment of different instrnments to nearly the same degree of sensitiveness should be possible ; Its equilibrium should be unstable; that is, when once dis- turbed it should not “ reset”’ itself; It should not be liable to register phenomena other than actual movements of the earth upon which it rests. While much has been done and notable advances have been made in the construction of seismographs with a view to the determination of the character of the motion of the earth particle, it does not appear that a seismoscope satisfying these conditions has yet been described or extensively used, although an infinite variety of instruments bearing the name have been devised. If whatever is done in the near future is likely to be done through the use of the time-registering apparatus, and this, I believe, is the opinion of the majority of the members of the earthquake Commission assembled upon the invitation of the Director of the Geological Survey, the subject becomes one of considerable importance, aud a recognition of this fact has resulted in the suggestion of several new forms of seismo- scopes within the last two or three years,a few of which have been actually constructed and tested. The first of them, and the only one as far as I know which has been used to register the occurrence of an earthquake in this country, was designed in the Physical Laboratory of the Signal Office at Washington. While others contributed suggestions as to certain details, the general form of the instrument is due to Junior Professor C. F. Marvin, of the office of the Chief Signal Officer.* It is shown in figure 1 and a little explanation will make its operation clear. An iron cylinder weighing three or four pounds has a cylindrical hole of about 2™ in diameter, bored through concentric with its axis. Ata point a little distant from the * The first practical use of an instrument of this type. was at the Flood Rock Explosion in October, 1885. It was placed by direction of the writer at the nearest point of observation, on Ward’s Island. Its performance was entirely satisfactory. See Science, Oct. 16, 1885. An instrument somewhat similar in design with a very imperfect contact-making device was suggested by Milne. See Trans. Seis. Soc. Japan, vol. iii. Seismological Investigations. 103 center of gravity this hole is suddenly diminished in diameter by a small amount, affording a shoulder against which rests a cross piece filling symmetrically only a part of the opening and carrying at its center, which is on the axis of the cylinder, a fine steel point. This point rests in a small depression on the inner side of a link, to which is attached a long steel needle as shown in the cut. The upper end of the link hangs upon a hook made of wire of the same diameter and rigidly attached to the supporting frame of the instrument which is of iron. By this arrangement for the suspension of the heavy mass, the link with its needle projecting downwards, has considerable freedom of motion in all azimuths, with little frictional resist- 104 T. C. Mendenhall—Seismoscopes and ance, and for slight movements the pivotal pomt within the cylinder may be regarded as fixed, Rotation takes place about this point and the motion of the earth, which is that of the hook upon which the link is suspended, is magnified at the point of the needle as many times as the ratio of the length of the needle to that of the link. A small and very light lever has its short arm bent upward, and is so adjusted that when the instrument is “set,” the upper end, ground to a fine point, rests against the pointed end of the long needle. The longer and heavier arm of this lever terminates in a platinum fork, the prongs of which are vertically above two small mercury cups forming terminals of the electric circuit. The operation of the instrument is simple. A very slight movement of the point of suspension is magnified at the needle point; the short arm of the lever is released and the fork drops, closing the circuit. Different degrees of sensitiveness are obtained by grinding the abutting points to greater or less dimensions. A seismoscope of great simplicity of design, and offering many advantages, is one originally due to Milne,* and more re- cently with slight modifications, experimented with by Hayden and Hallock, of the U. 8. Geological Survey, by whom it was © also, I believe, independently invented. It belongs to the family of liquid seismoscopes, of which many varieties have appeared, notably several devised and used by Palmieri. In all previous forms, however, the action utilized was the move- ment of the whole mass of liquid in relation to the containing vessel, while in this, advantage is taken of the well known fact that waves are, in general, produced upon the surface of a mass” of liquid when it is subjected toa sudden disturbance. In a cylindrical vessel these waves run from circumference to center, at which point the liquid is sensibly elevated for an instant, and through this elevation an electric circuit may be momentarily closed. Mercury is the liquid used, and it is placed in a small cylindrical iron box, through the cover of which a pointed screw with a large divided head runs. The point of the screw, which is of platinum, may be brought extremely near the surface of the mercury, its position and distance being known by means of the divisions on the head. A slight jar generates a series of waves, the elevation at the center completes the circuit through the properly insulated screw. The tendency of the mercury to become oxidized or dirty upon the surface so as to become inoperative was overcome by the use of a small platinum float, a device previously employed for measuring the height of the mercury in the cistern of a barometer by electrical contact. A * Trans. Seis. Soc. Japan, vol. iii. Seismological Investigutions. 105 simple arrangement for keeping this float in position is em- ployed and the real contact is between two platinum surfaces, being thus much more desirable and lasting. Several other forms of seismoscopes have been suggested and tried with more or less success. One of these is a modification of the well known Zéllner’s horizontal penduluin, the extreme sensitiveness to change in level of which has been so well shown by Professor Rood.* It is easy to arrange this so that an elec- tric circuit is closed when a disturbance occurs; and, although its greatest sensitiveness is for disturbance in one plane it is generally sufficiently delicate to respond to very feeble motions | in all azimuths. I have recently modified. the instrument first described, re- ducing its dimensions and cost, and greatly increasing the ease with which it is adjusted and “set.” The alteration consists principally in extending the multiplying needle upward instead of downward. This brings the cireuit-closing part of the ap- paratus above, where it is open to inspection and convenient for adjustment. The supporting frame rests upon a square or tri- angular base, and can be placed upon any convenient pier or table, instead of necessarily being screwed to a vertical support as inthe earlier form. ‘The latter plan was adopted with a view to fastening the instrument to a post driven in the earth, but it has been found inconvenient in practice, and it will gen erally be better to rest it upon the top of the post, if one is used, or upon a stone imbedded in the earth, or upon a bracket shelf attached to a foundation wall. The new form of the instrument is conveniently covered by an ordinary glass shade to protect it from dust and disturbance by air currents. An improvement is made in the arrangement for adjusting the position of the circuit closer, which is held to the table upon which it rests by means of a spiral spring, so that while it moves freely upon the application of a slight pressure it is sufficiently firm to resist accidental disturbances. The new form will be readily understood by examination of fig. 2 (p. 103.) Any mechanical device by means of which a temporarily “steady point” is provided may be utilized as a seismoscope. The horizontal pendulum, first suggested by Chaplin and utilized by Ewing in his seismograph, satisfies the requirements, except that its sensitiveness exists in only one plane. The use of some form of link motion for an astatic suspension was suggested by Professor West a few years ago, ata meeting of the Seismolog- ical Society of Japan.t It is clear that an ideal arrangement would be the Peaucellier linkage for straight line motion in a horizontal plane. But it is difficult if not impossible to avoid * This Journal, IIT, June, 1875. + Trans. Seis. Soc. Japan, vol. vi. 106 T. C. Mendenhall—Seismoscopes and an amount of friction which would be fatal. Ewing * has sug- gested the use of some form of linkage in which only ties should be used, so that flexible cords could be substituted for rigid bars. No rigorously straight-line motion is susceptible of this con- struction, but several close approximations may be utilized. An approximation is all that is required in a seismoscope, but it must possess freedom of motion in all azimuths. Professor Ames, of the Rose Polytechnic Institute, has devised a form consisting of a combination of two linkages of the form invented by Roberts. By arranging these in planes at right angles to each other, freedom of motion in any azimuth is secured. A heavy mass is pivoted at the tracing point and friction may be reduced to a minimum by the use of flexible cords, fine wires, or by pivoting light rigid links. The suspension is approxi- mately astatic, but sufficiently so for seismoscopic uses, and per- haps for seismographs—It is shown in figure 3. > uti A number of trials with several of these seismoscopes under different varieties of disturbance show that all are not equally sensitive to the same disturbance, however delicately they may be adjusted. The mercury seismoscope is peculiarly sensitive to disturbances produced by a slight jar of the table or support upon which it rests. In this case the vibrations are generally very rapid, probably from ten to fifty or more per second. It may readily be adjusted to respond to extremely slight tremors and besides it apparently affords the advantage of being set at any time to a definite degree of sensitiveness. With the two * Memoirs of the Science Dept., Tokyo Daigaku, No. 9. Secsmological Investigations. 107 or three instruments of this class upon which I have experi- mented, this theoretical advantage is not realized in practice. The distance between the two platinum surfaces is so ex- tremely small, when the instrument is sensitively adjusted, that very trifling and generally unknown causes will considerably modify the position of the divided head when contact occurs. The setting of the instrument is therefore a matter of great uncertainty. This instrument possesses what at first appears to be an ad- vantage, in that it is ‘‘self-setting ;’ but a reference to what has gone before will show that this is not considered a desirable feature of a seismoscope. In fact, it is very undesirable in my judgment, except where devices of a special character are made use of for securing time records. If the. epoch is established by stopping or starting a clock or by Milne’s printing device, a self-setting instrument would be objectionable. If the record is made upon the revolving drum of a chronograph, or on a continuously moving strip of paper, this form of seismoscope might fix the time of all sensible movements during the distur- bance, and might, indeed, play the part of a seismometer in some degree by distinguishing the more violent motions. But it would be likely to fail in this respect, as well as in its general performance as a seismoscope, owing to the peculiarity already referred to. To vibrations of moderately long period it does not promptly respond. Earthquakes seldom, if ever, begin with a sharp and sudden movement. The maximum vibration is nearly always preceded by several of less amplitude. and nearly the same period, which are themselves preceded by os- cillations of extremely small amplitude but of great frequency. The intensity of these preliminary tremors is not, in general, sufficient to cause a mercury seismoscope to act, and to the succeeding movements of greater amplitude but longer period, (often as long as one second) it is not sensitive. Further ex- periment and investigation is needed, however, to determine the relative merits of these and other instruments. Time APPARATUS. Various methods of time-registration have been made use of, and most of them are generally well known. A choice among them must depend largely on the probable frequency of earth- quake phenomena. In Japan and some other parts of the world rarely more than a few days pass without a sensible dis- turbance. A continuously operating chronograph would be desirable and profitable under such circumstances and various modifica- tions of the ordinary astronomical chronograph will at once suggest themselves as suitable for this work. When an earth- 108 T. C. Mendenhall—Seismoscopes and quake is a rare phenomenon, years instead of days elapsing be- tween two successive disturbances, all appliances for their observation must be of the utmost simplicity of construction consistent with certainty and accuracy of performance. A fairly good clock is a necessity and that beg provided it. re- mains to determine how it may be used in recording the instant of disturbance. One of three different schemes may be adopted: a running clock may be stopped; a clock at rest with hands set in a known position may be started, or the position of the hands may be registered without interfering with the going of the clock. Hither of these can be easily accomplished through the instrumentality of the electric circuit closed by the effect of the disturbance on the seismoscope. The simplest method is that of stopping or starting the clock, and considerable difference of opinion has existed as to the relative merits of these two pro- cesses. It will be seen at once that.the plan of starting a clock from rest ina known position would have many advantages, and one of them is certainly of great importance. It is that after the happening of the earthquake the started clock can be allowed to run until-a comparison with some standard time is possible and if necessary its rate may be determined, so that the exact epoch of the disturbance can be ascertained with consid- erable accuracy. On the other hand, if a clock be stopped our knowledge of the exact time of the occurrence will depend on our knowledge of its error at the time of stopping, which can only be known through previous observations of error and clock rate. Thus it will appear that if the method of clock stopping is to be resorted to, the clock must be under constant surveil lance and frequent comparisons must be made with some stand- ard time. ‘The clock-starting method is also open to some rather serious objections. A clock which has been at rest for months or even years is hardly likely to be constant in its rate during the first few hours after starting. This objection can be in a great degree removed, however, by carrying out suggestions to be given later. Another, and. more important, is that the re- cord is lable to be lost entirely through the subsequent stopping of the clock by the violence of the earthquake. The clock-stop- ping method is not open to this objection as it is difficult to imagine the starting of a clock by an earthquake, particularly if the pendulum is held somewhat firmly by the stopping appa- ratus. The third plan, that of registering the position of the hands of the clock at the moment of closing the cirewit without interfering in any way with the movement of the clock com- bines many of the advantages cf both the others, but has the disadvantage of being more complicated and difficult to accom- plish. It is easy to expose for an instant a quick photographic plate, upon which an image of the clock face is projected, but Seismological Investigations. ~ 109 we at once meet with the difficulty of properly illuminating the face at night. Among other methods which have been proposed, probably the most simple is that of Milne,* which consists in placing small pieces of cork, coated with an oily ink, upon the extremi- ties of the hands of the clock against which a paper or card board ring is pressed by electro-mechanical devices, put in operation by the closing of the circuit at the seismoscope. After an instant of pressure the ring is withdrawn, bearing a printed record of the position of the hands of the clock. This allows the determination of the error and rate of the clock either before or after the earthquake or both, and should the clock be stopped by a violent shock, the time record is not lost. These advantages will undoubtedly lead to the invention of simple and sure methods by means of which this printed record may be obtained. For stopping a clock, Milnet has used a thin piece of board in which notches are cut in one of which the pendulum is caught at the moment of the disturbance. This method is likely to allow and sometimes to cause considerable subsequent swaying of the pendulum and I have preferred to use simply a strip of brass, curved to an arc of the circle whose radius is the pendulum. ‘his lies always nearly touching the pendulum and is slightly lifted when the circuit is closed so as to arrest the pendulum. The brass strip is attached to the movable armature of a common telegraph sounder secured to the side of the clock case. The circuit remaining closed after the action of the seismoscope the pendulum is held in its place. APPLICATION, Two seismic stations with time-taking apparatus have been in operation in this country for nearly a year. The first was established in the Physical Laboratory of the Signal Office in Washington shortly after the occurrence of the Charleston Earthquake, and the second, at the Rose Polytechnic Institute, Terre Haute, Ind., was put in operation in January, 1887. Both are equipped with seismoscopes similar to that described and shown in fig. 1 and with clocks known as “ Regulator No. 2,” made by the Seth Thomas Co. These clocks were selected on account of their cheapness and their really excellent perform- ance as time keepers. The stopping apparatus is of the simple form already described, and an ordinary vibrating electric bell with battery is connected with it so that a continuous alarm is maintained from the time of the disturbance of the seismo- scope. * Trans, Seis. Soc. Japan, vol. iv. { Trans. Seis. Soc. Japan, vol. iii. 110 T. C. Mendenhatl—Seismoscopes and Since their installation these instruments have recorded as follows :— At Wasuineron.—From Oct. 6th, 1886, to Nov. 4th, 1887. Date. : Time, (75th Mer.) Remarks. h. m. sec. October 22, 1886 ____-..- BAG) MAb to, Sook eos Felt generally in the vicinity. November 5, 1886__..___- WA) Pe ME oy hoe ote Bebruary; 23; 188/22 =2s2-2 J 83) Oem s ee sse Possibly related to the great Italian earthquake of that time. From the condition of the instrument before and after the time of the record it was thought to be reasonably certain that it was due to a true seismic disturbance. At Terre Havte.—From Jan. 18th, to Oct. 26th, 1887. Date. Time, 90th Mer. 5 Remarks. Nye SCC. Hebruanyo Wl eee see eee NO Bel BS) Os wie ees Shocks in Italy, Feb. 3. INVER, ilo o acco esse 2h 1h Oey meso kes. Shocks in Ind., Ill, Ky., and Mo. Hebruany; LOthess S322 s2ee TA PHA a, eee Papers reported shock at Jasper, Ind., but not veri- fied. iMiaverG thee ae elie ees th oe BP Pea BS ae a May 3d and 4th, general in Mexico and from Texas to Cal. 150 lives lost at Bahispe in Sonora, Mex., also many topographical changes. Mi easy, UO ihn eect a 6a el n34 yok aay ae Shocks in mountains daily, May 12 and 13, shocks in 8. C., Cal. and Arizona, May 19 and 20 in Europe. May 30 and 31, in Mexico. Maye 24 thee} ee taeainele es uae NO: oes BBE fs A se Shocks felt in Ind., Ill, Ky., and Tenn., and in Equador, 8. A INUG UE OOS sae we ee Ree UAT Be, By ENS Tl So osoe October 22d_____- eae Gijy Onaes Odean eee ees PLAN OF CAMPAIGN. In determining upon a systematic plan for the instrumental study of earthquake phenomena, some consideration of the fore- going remarks seems to be demanded, and some useful concelu- sions may be drawn from the brief experience already had. In the first place, it is claimed that.time observations are of the first importance and that under the circumstances such only should be undertaken. It is believed that the reasons briefly, and in some degree imperfectly, presented in the foregoing dis- Seismological Investigations. IDLO cussion, are sufficient to establish the claim. Seismoscopes, with the accompanying clocks, should be the only instrument used, and these should be, as far as possible, of the same type. Before the adoption of any one of several different species available, a careful study of them should be made, all being tested under similar conditions and these conditions should resemble as closely as possible those under which the instru- ment is expected to work. As seismic phenomena are here too infrequent to admit of such preliminary test or calibration, means must be provided for imitating at will the motion of a point upon the surface of the earth. Such an arrangement would also be useful in testing seismographs and the validity of their records. For this purpose what may be called a “ seismic table” has been designed. It consists essentially of a horizontal surface, large enough to furnish room for two or three seismoscopes or seismographs, and which by suitable mechanism may be given a vibratory motion in either one or all of three directions at right angles to each other, two of these motions being in a horizontal plane. The vibrations are all derived from a single piece rotating with a uniform angular velocity, and all are on a close approximation to simple harmonic motion. By a simple device their amplitude may be varied at will and without arresting the movement, from zero to a_ prescribed limit. Another mechanism enables the operator to vary the frequency of vibration from zero to any desired number per second. The machine is to rest upon a solid foundation and power is to be drawn from a steam or gas engine. At any moment, the amplitude and frequency of vibrations along any of the three components will be shown by suitably arranged indices. The disturbance to which a seismoscope is subjected can generally be resolved into approximately simple harmonic motions along these axes, and as the period and amplitude of vibration for earthquakes of moderate intensity are now toler- ably well-known, through the investigations of Japanese earth- quakes by Ewing, Milne, Gray and Sekiya, it will be possible to reproduce their movements with considerable accuracy and with such variations as to intensity as to satisfy every demand in testing seismic instruments. In this way it can be deter- mined to what particular species of vibration a seismoscope is sensitive ; whether the same seismoscope can be repeatedly set to the same degree of sensitiveness, and whether several differ ent instruments can be made to agree in this respect. In addition to its great value.as affording a means of testing and comparing instruments, it is believed that such an apparatus may be useful in studying certain observed effects of earth- quakes upon simple structures. By submitting small but © 112 T. C. Mendenhall—Seismoscopes and dynamically similar models of such structures to differently compounded vibrations and studying the results, some light may be thrown upon the confusing and often contradictory phenomena of actual earthquakes. Assuming that a satisfactory form of seismoscope has been selected by subjecting all proposed or submitted to the test of the seismic table, it is important to consider next their distri- bution and use. As it is very desirable that they should be as numerous as possible, and as the cost of the equipment of a station is of great practical moment, it may be stated that the whole outfit for a single station, including clock, seismoscope, battery and all, need not cost more than twenty-five dollars, and it is hoped that a sum considerably less than that amount may be found sufficient. In selecting stations it is of the utmost importance that the question of accurate time should be first considered. Standard time signals from one observatory or another are now distributed so generally over the whole country, that in any considerable town no difficulty will be found in determining the clock error and rate, provided that the apparatus is in the hands of a suitable person. It is likely that in many instances jewelers or watch makers, who receive time signals daily will be willing to undertake the care of a seismic station. The seismoscope may be mounted upon a bracket secured to the stone or brick foundation of a building, in the cellar or basement, while the clock should be placed where it will be often seen, or where it may be of real service as a time-keeper to the observer. The use of an electric alarm, while not a necessity, is very desirable, as through its action attention is immediately called to the disturbance, and even a second or two of warning might enable many interesting observations of phenomena which would otherwise escape the observer. I have found it very useful to provide for regular tests of the apparatus on the first of each month. An artificial disturbance near the seismoscope takes the place of a real earthquake and the operation of the bell-ringing, clock-stopping apparatus is observed, the clock error and rate applied, and in fact every- thing is done as if a real earthquake had occurred. This will enable the observer to detect any fault in his arrangements and will serve in a great degree to maintain his interest and sustain his patience through months or years of waiting for an actual record. Blanks should be furnished on which the results of these tests may be recorded and forwarded to the person in charge of the whole system of observations. Many other de- tails might be referred to, but they belong rather to a code of instructions for observers. There is one matter connected with the establishment of stations, however, which experience has shown to be important. Seismological Investigations. 113 The records of a seismic station, even when equipped in the best possible manner, will be unquestionably affected by what may be called “accidental errors.” That is to say, it is be-. lieved that the best of seismoscopes will fail to satisfy entirely the conditions given above and will occasionally “go off” when there has been no real seismic disturbance. This may be due to a variety of causes, among which may be mentioned: changes in the position, level, ete., of the support of the instrument, through a slow movement of the wall or pier to which it may be attached ; occasional movement of heavy bodies in close proximity to the instrument; very violent winds which may disturb the foundation of the building in which it is placed, ete. It is often difficult to distinguish a false alarm thus given from a true seismic disturbance and in the records of the seis- moscopes at Washington and Terre Haute already given, two or three doubtful instances occur. When the earthquake is sufficiently violent to be detected without instrumental aid, confirmatory evidence is furnished ; but one of the principal objects in making use of instruments is to detect movements which would otherwise pass unnoticed and to extend the range of observation of the more violent far beyond what it can be at present. As an illustration of the great importance of being able to know a genuine record I may invite attention to one of the records made at Washington a few hours later than the Italian earthquake of last year. The epoch of the disturbance is such that there is nothing unreason- able in supposing that it was really a wave which had been transmitted across the sea or through the crust of the earth. Interesting as this fact would be, it would be rash to make such an assumption in view of the possibility of a purely accidental disturbance of the instrument. A very similar state of affairs exists in connection with one of the records of the Terre Haute seismoscope. Had there been several instruments along the Atlantic coast they might have confirmed or confuted the record made at Washington. It is highly probable, however, that disturbances frequently oc- eur which do not affect large areas. In arranging for the systematic observation of phenomena so rare and so uncertain as to time and place as earthquakes, it will hardly be possible to place stations sufficiently near each other to insure the de- tection of these minor movements, although they are for many reasons of prime importance. With the possibility of accidental disturbance and with seismoscopes somewhat widely separated, it would seem impossible ever to certainly detect such minor movements in the surface of the earth. There is a remedy, however, and it lies in the precaution, the truth of which ex- AM. Jour. Sct.—THIRD SERIES, VoL. XXXV, No. 206.—FEB., 1888. 7 114 G. H. Williams—Petrographical Microscope. perience has forced upon me, that wherever there is one seismo- scope there must be two. That is to say, when any locality is selected as a suitable place for a seismic station two complete stations must be established, separated sufficiently so as not to be liable to the same accidental disturbances but near enough to render it reasonably certain that a real seismic disturbance which affects one will also affect the other. If separated by a distance of from a few hundred feet to a quarter or half a mile, the necessary conditions would be satisfied. Two such stations ought to sensibly agree as to the exact time of any dis- turbance and not only would they enable the observers to dis- tinguish accidental or false alarms, but they would afford exeel- lent checks upon each other on the occasion of a genuine re- cord. It is hardly necessary to refer to the interesting and impor- tant results which would almost certainly come from the or- ganization of one hundred or even fifty such stations wisely distributed, at first over those sections of the country known to be most subjected to earthquakes. On the hypothesis of trans- mission through a homogeneous, elastic medium, records at less than a half dozen stations will suffice to determine the velocity of transmission, and the coordinates of the origin of the disturb- ance. Although in the case of the earth this hypothesis is not tenable, it is an approximation to the truth, and there can be no doubt that the mean of a number of such determinations, based upon different groups of observations would have consid- erable weight in the discussion of the dynamics of the problem. I think it will be generally admitted that the management and direction of an investigation so extensive as the territory involved could only be successfully carried out by the govern- ment; and that the Director of the Geological Survey, of whose disposition in the matter there can be no doubt, should be fur- nished by Congress with the authority and material for its accomplishment. Art. [X.—On a new Petrographical Microscope of Ameri- can Manufacture ; by GrorGE H. WILLIAMS. THE importance of the microscope in geological investiga- tions—particularly in the domain of the crystalline rocks—is now universally recognized, even by those geologists who do not themselves employ it. The light already shed upon some of the darkest and most intricate problems by recent petro- graphical methods, uncertain though it sometimes be, is full of promise for the future. Geology is reaping almost as great G. H. Williams— Petrographical Microscope. 115 benefits from the application of the microscope as her sister sciences, biology and medicine ; and there seems to be no good reason why this instrument should not be made of as much educational value in her field as in theirs. Not all who study the natural sciences are able or care to become original investigators. The scientific training, how- ever, possesses for every one certain peculiar advantages, and the organic sciences have not been slow to appreciate how val- uable a factor in such a training the microscope may be made. Five years of practical experience have convinced the writer that the microscope in geology may, with as great success, be employed for purely educational purposes. If then the microscope be of such use in geology, both as a means of research and as an educational discipline, the pro- duction of instruments especially designed for rock-study be- comes a matter of importance. Such a demand has for some time past been met, with varying success, by several Continental manufacturers ; but, owing to the limited interest in micro- geology on this side of the Atlantic, the attempts of American makers to supply petrographical microscopes have hitherto been wholly inadequate. : The advantages to the constantly increasing number of pet- rographical students in America, of a suitable instrument of home manufacture, are too apparent toneed enumeration. In- deed, the actual demand for such an instrument has been so often and so urgently forced upon the writer’s attention, that, at his request, the well-known Bausch and Lomb Optical Com- pany of Rochester, N. Y., undertook the construction of a purely petrographical stand which should satisfy all the de- mands for mineral and rock study and at the same time come within the means of geological students. Hach essential point was designated by the writer and has been elaborated by the manufacturer in the simplest and most inexpensive manner con- sistent with satisfactory results. The instrument in its present shape, though it may be subject to further improvements, offers at a reasonable price ($135.00) a complete petrographical and mineralogical microscope of excellent workmanship, possessing all essential features, and several advantages (such as a sliding analyzer and mechanical stage) to be secured only on the more expensive European stands. It has been thought that a figure and description of this microscope would prove of interest to all whose attention is devoted to geology, whether as teachers or as investigators. . The accompanying cut shows the instrument constructed upon what is known as the Bausch and Lomb “ Jfodel Stand.” (See Bausch and Lomb Illustrated Catalogue for 1887, pp. 15.) This has a frame of japanned iron, with brass tube, stage and 116 G. H. Williams—Petrograghical Microscope. -‘mirror-bar. It was selected in order to reduce the total ex- pense as much as possible, but all the petrographical appliances may be adapted to any of the brass stands of this firm, if de- sired, with a proportionate increase in expense. (One-third natural size.) The screw supporting the arm between the pillars allows the instrument to be inclined at any angle. The main tube is pro- vided with a cloth lining into which the draw-tube carrying the ocular, is fitted. There is a coarse adjustment by rack and pinion and a fine adjustment by a micrometer screw. The mirror is both flat and concave and the mirror-bar adjustable. Coming now to the peculiarly petrographical features, we have the lower nicol-prism or polarizer enclosed in a cylindri- cal metal box, both ends of which are protected by glass. This box is capable of a complete revolution and is provided G. H. Williams—FPetrographical Microscope. a7 with a graduated silvered circle and index. It is held by a cylindrical frame in which it may be raised or depressed at will by a rack and pinion movement. This frame is attached to the under side of the stage by a swinging arm, so that the whole polarizing apparatus may be thrown to one side if de- sired. A strong compound lens may be screwed upon the upper end of the polarizer whenever strong illumination or converged polarized light are needed. The circular stage (9°5 em. in diameter) is provided with a beveled silvered edge, graduated to degrees. Upon this is mounted for smooth and concentric revolution the admirable mechanical stage, known in the manufacturer’s catalogue as No. 1052. This carries an index for reading the graduated circle, and is also provided with silvered graduations for its two rectangular movements, whereby any point in a section can be readily located. The upper sliding bar which carries the object has been shortened so as to be only flush with the re- volving stage when pushed to its extreme limit on either side. With this, square or short rectangular glasses must be used for mounting which will avoid any interference with the revolu- tion of the stage. Into the nose-piece, just above the objective, is an opening intended to receive the four following accessories, each mounted in a separate brass frame: (1) a Bertrand lens for magnifying the interference figures; (2) a quarter-undulation mica-plate ; (3) a quartz wedge; (4) a Klein quartz-plate or a gypsum plate with red of the first order. The centering of the various objectives is secured by two screws having motions at right angles to each other. The upper Nicol-prism or analyzer is inserted in the tube in order to avoid the diminishing of the size of the field which is unavoidable when the prism is placed over the ocular as a cap. To accomplish this, and at the same time to keep the tube dust-tight, the nicol is enclosed in one side of a double cham- bered box. The other side is left vacant and the box may be slid to and fro according as ordinary or polarized light is de- sired. A metal sheath protects this box from above. The microscope as here described in a case with a single eye- piece, but without objectives, may be obtained for $108.00. With two eye-pieces (one with cross-hairs and the other with micrometer) and two objectives (Zand 4 inch) its cost is $185.00. The cost of a solid brass stand is about $25.00 more. The instrument as here figured is less expensive than the importation of the lower grades of European petrographical stands; and considerable practical experience with it has shown that it renders decidedly better service. Petrographical Laboratory, Johns Hopkins University, November, 1887. 118 W. B. Clark—Ammonite from the Alpine Rhetic beds. © Art. X.—A new Ammonite which throws additional light upon the geological position of the Alpine Rhetic; by Witiiam B. CLARK. In a paper* upon the geology of a part of the northern Tyrol, published in Munich in February, 1887, I described among several new forms a species of ammonite of the genus Arcestes, which is of some considerable importance, as pointing to the probable position of the Rheetic beds. In the region above mentioned this much debated formation consists of the three typical divisions of Haupt Dolomit, Koéssener Schichten and Dachstein Kalk, the lower or Haupt Dolomit being plainly subdivided into a zone of dolomite of somewhat over 1,000 feet in thickness, overlaid by a thinner zone of limestone, the so-called Platten Kalk of Gimbel. The lower zone is probably unfossiliferous, with the exception of some interstratified beds of asphalt which contain ganoid scales ; while the upper, although containing numerous ill-de- fined gasteropods, doubtless of the genus /zssoa, affords no distinctive forms that would of themselves demand a close union either with the underlying Trias or overlying Jura. The Kossener Schichten, in contradistinction to the lower division, are very fossiliferous and present the chief ground of discus- sion. The rock is a dark limestone, often of a marly, schistose character, with frequent interstratified beds of marl, that grades down insensibly into the Platten Kalk. The fossils show nu- merous affinities both with Triassic and Jurassic forms, but for the most part appear to be of the former character. They are largely corals, brachiopods and lamellibranchs, and the exam- ple here cited is the first case of a well-defined ammonite. The genus Choristoceras,so commonly encountered, is a degen- erate form placed with the Ceratitidw, and has small value in this connection. The third division, the Dachstein Kalk, is of white limestone, and contains almost exclusively lithodendron- like corals, though the large Megalodon triqueter, the charac- teristic bivalve of this zone, is frequently encountered. It is without doubt of coral-reef origin, as many physical facts along its contact with the Lias give proof. Facts seem to indicate that these different divisions, certainly so far as the Kdssener Schichten and Dachstein Kalk are con- cerned, are only facies, and may under suitable conditions be interchangeable. * Ueber die geologischen Verhaltnisse der Gegend nordwestlich von Aachensee mit besonderer Beriicksichtigung der Bivalven und Gasteropoden des unteren Lias. 8°. 45s., 2 taf., 1 Karte. Miimchen, 1887. (Inaugural Dissertation). W. B. Clark—Ammonite from the Alpine Rhetie beds. 119 When we examine the stratigraphical relation of these beds to the underlying Trias we find that no unconformity exists, but that an insensible gradation often takes place from one to the other ; while toward the Lias, on the other hand, although unconformity does not exist, yet the break is so marked and clearly defined that we are unprepared to admit an intimate connection between the Rheetic and Lias. Stratigraphical and paleontological evidence in the Eastern Alps is, then, strongly indicative of a close affinity of the Rhetic to’Trias ; and the Arcestes species, which we will now describe more in detail, adds another important proof to this more or less generally accepted fact. ARCESTES RHAETICUS, n. sp.* The ammonite in question, to which, from its important oc- currence, I have given the name of Arcestes rheticus, has the foliowing dimensions : HD cian Ge yee eer aN aa eNO One eiohtrotlast whorls ss pyeger ene sel ws 40 ADM OTC Cera ek cet Me's aA aS Sa Sg MN eR a 50 LW nrao ne ea Sy pai Metro ne Meee Nee aN gheg ae 14 The shell is involute, with rounded dorsal surface, and the east shows upon the last whorl two depressions, which run in a straight line over the convex back, and which were ocea- sioned by successive contractions or interior thickenings of earlier mouth-edges. The sutures form regularly decreasing series of lobes and saddles from the dorsal siphuncle toward the interior. These lobes and saddles are finely branched, the lat- ter containing upon the outside 4-5, upon the inside 3 ob- liquely diverging divisions. Beyond the dorsal and the two lateral saddles there are only two auxiliary saddles present. The dorsal lobe is divided by a median saddle into two points, which are very considerably deeper than the lateral lobes. The latter are by means of small branches two- or three-pointed. This species belongs to the group of the Galeati, and shows close affinities to Arcestes giganto-galeatus Mojs., from the Hallstadter Kalk. ; We have thus a form which belongs to a family and genus most characteristic for the Trias and until now never found above that formation. The Lias has not a single representa- tive. The interest in this particular species is greatly height- ened from the very close similarity in outward form and mi- nute division of the lobes to Arcestes giganto-galeatus. This fact, if we were to consider the Rheetic beds as belonging to the Lias, would be without a parallel, for on account of the ex- * Figured in the paper before mentioned, Plate I, fig. 3, a, b, c. 120 W. J. McGee—Three Formations of treme variability of the ammonites, the most marked changes are shown from stratum to stratum. Hence it is scarcely pos- sible that a well-marked form could be preserved through any considerable extent of time or any marked change in the con- ditions of life. In other classes of animals many cases can be cited where forms have continued unchanged for long periods of time, but when such is observed among the ammonites it is certainly a proof of the faunal affinity of the formations con- ' sidered and a strong reason for uniting them most closely in the geological system. Before closing this brief contribution it will not perhaps be irrelevant to refer in a word to the general positions held by geologists of different countries upon this question, as shown in their reports to the Committee for the Unity of Nomencla- ture at the Geological Congress at Berlin. In this report the opinion of French and English geologists was decidedly in favor of according a closer relationship of the Rheetic beds to Lias than to Trias, while the weight of evidence obtained from Ger- man sources plainly pointed to the opposite conclusion. The inability and folly of endeavoring to correlate the strata of widely separated regions is thus most forcibly shown, since facts which in certain localities warrant the close association of conformable beds, in others preclude the union of apparently synchronous horizons. Geological Laboratory, Johns Hopkins University, Oct. 1887. Art. XI.—Three Formations of the Middle Atlantic Slope ; by W. J. McGes. With Plate Ii. INTRODUCTION. Tue Middle Atlantic Slope may be described as that portion of Eastern United States which sheds its waters directly into the Atlantic Ocean and in which the principal rivers rise within the Appalachian mountain system. Thus defined, it extends from near the Mohawk and Hudson on the north to the Roanoke (called the Staunton in the middle part of its course) on the south, or from southern New York to northern North Carolina. Its principal rivers, in addition to those mentioned, are the Delaware, the Susquehanna (including its continuation, Chesapeake Bay), the Potomac, and the James; and its smaller but yet notable streams extending to tide water are the Raritan, the Schuylkill, the Brandywine, the Patapsco, the Patuxent, the Occoquan, the Mattaponi, the North Anna and South Anna (which unite to form the Pamunkey), the Appomattox, the Nottoway, and the Meherrin. * & the Middle Atlantec Slope. 121 By geologic structure, by topographic configuration, by behavior of streams, and by the various cultural conditions re- sulting from these natural conditions, the Middle Atlantic Slope is separable into three distinct zones :—viz, the Appa- lachian zone, the Piedmont region, and the Coastal plain. In the Appalachian zone the rocks are Paleozoic, and are characteristically corrugated by greatly elongated flexures; the predominant topographic characteristic of the region is long, parallel ridges separated by flat-bottomed valleys, the whole —save the sharpest ridges—diversified by a plexus of narrow stream-cut valleys and intervening minor hills; the great rivers wander meanderingly through the mountain ranges while the smaller streams and secondaries generally gather in elongated basins bounded by the ranges, and both large and small streams flow rapidly over the rocky bottoms of narrow, steep-sided ravines or gorges; and the civil boundaries and the routes of travel and traffic are generally determined by the parallel ridges and greater waterways, while the industries are deter- mined largely by the resources of the rocks—anthracite and other coals, iron, building-stone, etc.,—the thin-soiled mountain slopes being unsuited for agriculture and allied pursuits. The Piedmont region comprises an area of highly inclined erystalline rocks, abundantly diked, veined and faulted; its surface is a rather strongly undulating plain without con- spicuous eminences, inclined seaward, and everywhere graven deeply by the larger and to proportionately less depths by the smaller waterways, which thus give origin to endless mazes of minor hills; its hydrography comprises the great rivers which meander irregularly through it, and a widely- branching dendritic system of secondary and tertiary drainage in which the individual members have no uniformity in direc- tion, in which the basins are irregularly rounded or pyriform, and in which the divides are low and inconspicuous and con- stantly curving and recurving in labyrinthine convolutions; while, as in the Appalachian region, both the larger and smaller streams are unnavigable and rush rapidly over the rocky bot- toms of sharply cut valleys, the declivity of the streams cul- minating at the seaward side of the zone, where all, river and rivulet alike, descend to tide level in cataracts and rapids. The civil boundaries of the region follow the waterways and transect the divides, the lines of traftic are either confined to the greater valleys or distributed over the surface, and the pursuits ee the people are largely determined by the soil and its pro- ucts. In the southern part of the area, the Appalachian and Pied- mont zones are sharply separated by the Blue Ridge—the east- ernmost member of the parallel Appalachian series; but in 122 W. J. McGee—Three Formations of Pennsylvania this mountain ridge looses its integrity and con- tinuity and the boundary between the two zones is indefinite, while in northern New Jersey and southern New York the natural boundary fails and only an arbitrary demarkation can be drawn between the zones so sharply distinguished im’ Vir- ginia and Maryland. The Coastal plain extends from the line of cataracts and erystalline rocks to the ocean. Structurally, it consists of generally incoherent deposits of later Mesozoic and Cenozoic age, slightly inclined seaward but otherwise undisturbed ; topographically, it is a plain, trenched by broad but shallow tidal estuaries and thus separable into smaller plains which sometimes undulate gently but irregularly, and again take the form of steeply-scarped terraces miles in extent, cut by steep-sided ravines and deeply scalloped along the greater waterways; the hydrography comprises the broad flat-bottomed estuaries into which the principal rivers are transformed on entering the plain, and local drainage systems of widely branch- ing dendritic type in which the principals are also generally estuarine toward their mouths; the divides are but labyrinth- ine and crenulated remnants of an imperfectly drained plain only partially invaded by erosion; and throughout the region the water is slack except toward the heads of the adolescent drainage ways. The political boundaries and principal lines of traffic are determined by the great water avenues, while the civil boundaries and lesser lines of traffic are independent of the physiography, and the industries grow out of the products alike of sea and soil and out of the natural facilities for traflic and transportation. The common boundary of the Piedmont region and the Coastal plain is one of the most strongly marked physiographic and cultural lines on the land surface of the globe: On the one hand there is a great series of crystalline rocks giving ori- gin to a characteristic soil in which all streams, from the great- est rivers to the smallest brooks, flow through constricted gorges ina succession of cataracts or rapids; while on the other hand there is a series of incoherent and undisturbed de- posits of clay, sand, and gravel through which the waters, gathering in the more elevated zones, move sluggishly in broad tidal estuaries. The boundary has long been known among students of manufacturing industries as the fall-line ; yet it is even more noteworthy as a line of deflection in the rivers than as one of declivity. The great waterways of the Middle Atlantic Slope maintain their courses through Appalachian ranges and Piedmont highlands alike; but on reaching the low- lying Coastal plain they are turned aside, literally by a sand- bank little higher than their depth, and thence hug the hard the Middle Atlantic Slope. 123 rock margin for scores of miles before finally finding their way into the open ocean. By this deflection of the rivers the north- ern half of the Coastal plain is nearly insulated; the isthmuses between the Raritan and the Delaware, between Claybank creek and Elk river, between the Patapsco and the Anacostia, and between Potomac creek and the Rappahannock, from tide- water to tide-water, are low, and but 20, 15, 25, and 5 miles in width respectively; measured directly along the fall-line, so that, the Hudson is barred from the Rappahannock by only about 60 miles of land and unnavigable water. The deflected portions of the rivers indeed occupy a great trough skirting and accentuating the Piedmont escarpment.* This remarkable physiography has materially affected the culture of the region: The pioneer settlers of the country ascended the tidal canals to the falls of the- rivers where they found, sometimes within a mile, clear fresh water, the game of the hills and woodlands and the fish and fowl of the estuaries, and, as the population in- creased, abundant water-power and excellent mill sites, easy ferriage and practicable bridge sites; here the pioneer settle- ments and towns were located ; and across the necks of the in- ter-estuarine peninsulas the pioneer routes of travel were ex- tended from settlement to settlement until the entire Atlantic Slope was traversed by a grand social and commercial artery stretching from New England to the Gulf States. As the population grew and spread, the settlements, villages, and towns along this line of Nature’s selection waxed, and many of them yet retain their early prestige—for Trenton, Philadelphia, Wilmington, Baltimore, Washington, Fredericksburg, Rich- mond, and Petersburg are among the survivors of the pioneer settlements; and the early stage route has become a great railway and telegraph line connecting North and South as they were connected of old in a more primitive fashion. The in- fluence of natural conditions upon man and his institutions is nowhere else more strikingly exemplified. No discussion of the phenomena of the Atlantic slope is intelligible without clear comprehension of the great physio- graphic divisions into which it is naturally separated. These divisions are represented ‘graphically in the accompanying stereogram, which also exhibits the essential continuity of the Coastal plain to the great submarine escarpment off the Atlan- tic coast; the submarine profiles being based on soundings by the Coast Survey, the Fish Commission, etc., while the indi- cated sub-marine structure is hypothetic. * It is shown elsewhere (7th Annual Report, U. S. Geol. Survey) that this trough is due to a post-Tertiary displacement along which movement is now in progress, probably at a rate as high as in the well-known recent faults of the Wasatch or the Sierras. 124 W. SJ. McGee—Three Formations of Four years ago the writer undertook to ascertain the origin and relations of certain conspicuous deposits in the District of Columbia, under the direction and auspices of the U. S. Geological Survey. It was soon found that while certain for- mations of the region—especially those containing fossils,— had received more or less study, while the various formations had been classified by means of the fossils contained in a few of them, and while the entire region had even been repeatedly mapped geologically, nothing was accurately known of the exact relations of the different fossiliferous and unfossiliferous deposits forming the portion of the Coastal Plain within and contiguous to the District of Columbia; it was soon found, moreover, that the formations in question are not only gen- erally unfossiliferous in the district, but that the deposits themselves are destitute of constant and definite petrographic and structural characters whereby the stratigraphy might be ascertained ; and thus it was early found difficult, if not impos- sible, either to correlate the different local exposures and de- posits among themselves, or to establish their relations to formations already classified elsewhere by commonly employed methods. Accordingly, the investigation was commenced de novo; and in default of fossils or definite structural characters, locally applicable methods, standards, and criteria were devel- oped as the work progressed: Conditions of deposition were inferred from deposits, and continent-movement was in, turn inferred from evident conditions of deposition superinduced thereby ; conditions of degradation in unsubmerged areas were inferred from the topographic forms thereby developed, and, since degradation is preéminently dependent on base-level, another means of inferring continent-movement was thus evolved ; the record of events interpreted from earth-forms fashioned in accordance with determinate principles on the one hand was compared with the record interpreted from cor- relative deposits on the. other hand, and history was thus de- duced from independent but consistent and cumulative testi- mony; and final correlations were made through deposits regarded not only as rocks but also as indices of continent movement, and at the same time through the correlative topo- graphic forms. In short, the methods, standards, and criteria have been of necessity physiographic rather than paleontologic or petrographic. Certain preliminary results of the work appear of sufficient moment to merit a place in the standard medium of American students of science. They are summarized in the following pages. In the present sensitive if not revolutionary condition of geologic terminology, it may be wise to define, without spe- the Middle Atlantic Slope. 125 cially defending, the term “ formation” as employed in this article. It is applied to a naturally defined series of deposits, evidently formed by a definite set of agencies within a deter- minate area during a definitely limited period—an easily rec- ognizable structural, chronologic, and taxonomic unit. The formations described are: (1) the Potomac, consisting of irregularly bedded and heterogeneous sand, clay, arkose, gravel, ete., of Mesozoic age and forming the base of the series of unaltered deposits of the Coastal plain, named from the river on which it is best developed; (2) the Appomattox, a series of predominently orange-colored sands and clays of later Tertiary age, also named from the river on which it is typically exposed; and (8) the Columbia, a series of delta and associated littoral deposits formed during a brief period of submergence in early Quaternary time, named from the dis- trict in which it is typically developed and in which it is first systematically studied. Certain deposits of each of the for- mations have already been investigated by different geologists, but they have not hitherto been correlated and systematically combined. The Potomac formation has already found place ‘in geologic literature and taxonomy; the Columbia has been defined and briefly described in print ;* but the Appomattox is here defined and named for the first time. Professor William M. Fontaine began his elaborate investi- gations of the later Mesozoic formation and its flora in Vir- ginia some time before the study of the contemporaneous deposits of the District of Columbia was taken up by the writer; but a meeting was soon arranged, notes were compared and exchanged, and a detailed examination of the principal exposures in Virginia, in the District, and in Maryland south of Baltimore, in which Mr. Lester F. Ward participated, was undertaken in the summer of 1885; during this joint study the characters of the Potomac formation were worked out and its name (previously proposed by the writer) adopted, the Appomattox formation was discriminated, and many features of the Columbia formation were brought to light; and it isa _ pleasure not only to acknowledge indebtedness to these gentle- men, and especially the former, for the greater share of our knowledge of the Potomac and Appomattox formations, but to record their substantial concurrence in the following state- ments and inferences concerning them. It is an equal pleas- ure to add that the phenomena of the Columbia formation have been more or less carefully examined in the vicinity of Washington by the same gentlemen and several other geolo- * Rep. Health Officer of the District of Columbia, 1884-85 (1886), 20; this Journal, III, xxxi, 1886, 473; Proc. A. A. A. S., xxxvi, 1888, 221; ete. 126 W. J. McGee—Three Formations of gists, that acknowledgments are due to them for pertinent and valuable suggestions, and that all coincide in the essential con- - clusions as to its genesis and age set forth in subsequent pages. Tue Poromac ForMATION. Character and Distribution—The southernmost observed occurrence of the formation is at Weldon, N. C., where a bed of obscurely stratified arkose, interspersed with well rounded quartzite pebbles, appears in the north bank of the Roanoke beneath the railway bridge. The deposit rests on an unequally eroded surface of gneiss, is not over a foot thick, and is unfos- siliferous ; but its composition and structure are characteristic, and there is little doubt as to its identity. Better exposures occur on the Nottoway river just below Bolling’s bridge. An irregularly and obscurely stratified arkose, unquestionably belonging to this formation, here rises four or five feet above low water, and is unconformably over- lain by three or four feet of stratified greenish-blue clay contain- ing Eocene fossils ; and exposures of similar character occasion- ally occur in the river channel within the next five miles up stream. In all of these outcrops the deposit exhibits a typi- cal and easily recognizable aspect: it is a nearly homogeneous, granular, loosely aggregated, almost mealy mass of quartz grains (generally angular but sometimes rounded), flakes and grains of kaolin (sometimes so little decomposed as to retain the form of the parent crystals of feldspar), and scales of mica, with an unimportant admixture of loamy particles, and now and then a rounded or irregular pellet of white plastic clay. The fresh surface is commonly light gray in color, but is fre- quently flecked with white and stained with brown in curiously curved lines. In structure it is either massive or obscurely stratified and cross-laminated ; but even where the bedding is most distinet it is rarely consistent and continuous for more than a few feet vertically or a few yards horizontally. Except for its obscure structure planes, its pellets and lenticular pock- ets of clay, and the slight admixture of loamy matter, the mass could hardly be distinguished from decomposed granite or gneiss in situ. Some of these deposits on the Nottoway river were observed and referred to the “secondary class of rocks” by W. B. Rogers in 1839 ;* but @ propos to the inter- esting question of geographic changes during the historic period, it is significant that Rogers failed to find the formation where it is now best exposed but found it “nearly on a level with the water” at a point “about 4 miles above Bolling’s bridge” where it now rises fully 8 feet above the river; the * Geology of the Virginias, 1884, 261. the Middle Atlantic Slope. 127 indications being that the river has here deepened its channel several feet since 1839. The next exposures of the formation occur on the Appomat- tox between Petersburg and its mouth at City Point; the most conspicuous being Point of Rocks (some four miles above the mouth) where the larger part of the material is an arkose simi- lar to that on Nottoway river, interspersed with well rounded quartz and quartzite pebbles and rounded or irregular masses of plastic clay, interstratified with laminated clay beds, and the whole so firmly lithified that the solid quartzite pebbles fracture as readily as the matrix. The deposit here forms a prominent bluff 50 or 60 feet high, the material of which has been largely quarried as a building stone. On James river the formation is notably exposed between Richmond and Deep Bottom, a few miles above the mouth of the Appomattox. Perhaps the most abundant constituent is arkose, such as oceurs on the Nottoway, generally friable but sometimes lithified ; but the arkose beds are frequently interca- . lated with beds of massive or laminated clay and heterogeneous sand or gravel, sometimes forming the greater part of the mass. Where laminated, and especially in the lenticular bands inter- ealated between beds of arkose, the clay frequently contains well preserved impressions of leaves; and silicified wood is common in the sandy and gravelly portions, as are lignitized trunks and branches of trees in the beds of clay. One of the most conspicuous elements in the deposits exposed on James river is its large pebbles and bowlders, reaching three or four feet in diameter, sometimes of Piedmont gneiss (which crops out in the river channel within a few miles of Dutch Gap), but more frequently of quartzite sometimes containing Scolithus borings and casts of brachiopods identifying it with the axial quartzites of the Blue Ridge. It is noteworthy that W. B. Rogers recognized the materials of this formation in borings from an artesian well at Fort Monroe at a depth of 835-907 feet.* Interesting exposures of the formation occur on the South Anna river (where, as at Point of Rocks, it is in part a firmly lithified arkose containing well rounded pebbles of quartz and flakes and pellets of plastic clay) as well as on the Little river, the North Anna, the Mat, the Taponi and its tributaries, on Massaponax creek, and indeed in nearly every considerable valley or deep ravine, and occasionally on the surface, between the South Anna and the Rappahannock. It is generally over- lain by the orange sands and clays of the Appomattox forma- tion; and in the neighborhood of Hanover Junction it reposes uncontormably upon the petrographically similar, but disturbed * Thid., 733-5. 128 W. J. McGee—Three Formations of and diked, Rheetic beds. Here too, the quartzite pebbles, so abundant on the James and Appomattox, disappear. About Fredericksburg the formation is well exposed and ex- hibits some noteworthy characters: it consists predominantly of locally lithified arkose with abundant pebbles either irregu- larly disseminated or arranged in bands and beds, and numerous bowlders of gneiss and vein-quartz (quartzite being altogether absent) up to two feet or more in diameter, together with hete- rogeneous sand containing a considerable element of finely divided diffused clay; while lenticular beds of clay are fre- quently intercalated in both arkose and sand, and in some expo- sures constitute the major part of the mass. As on the James, the clay is massive, obscurely bedded, or finely laminated, and sometimes contains abundant leaf impressions; and here, as elsewhere, silicified and lignitized wood are common in the sand ~ and clay respectively. Thus, south of the Rappahannock the formation consists of an indivisible mass of arkose, sand, clay and gravel, generally overlapped by the Tertiaries, and exposed only along waterways . and over a limited area between the two Anna rivers. North of the Rappahannock the formation increases in vol- ume and in diversity, and forms the surface over a zone several miles in width between the Eocene margin and the Piedmont crystallines. Near the mouth of Acquia creek it has an observed thickness of 180 feet, mainly of lithified arkose (long known as a fairly valuable building stone and extensively used in old structures in Washington, Alexandria, and Fredericksburg), intercalated with plant-bearing clay beds. Midway between Fredericksburg and Acquia creek the characteristic phases of the formation as developed in the south are found to be over- lain by a bed of clay of obscure or inconstant structure, con- taining occasional intercalations of arkose or beds of pebbles ; and this clay deposit, which lies beneath the Eocene and is generally unfossiliferous, increases in thickness northward. At the same time, isolated patches of gravel identical with that of the body of the formation, and evidently outliers insulated by erosion, begin to appear along the marginal portion of the Piedmont zone, generally capping eminences of circumdenuda- tion. These outliers are sometimes 25 or 30 miles within the fall-line. Between Acquia creek and Washington the formation con- tinues to form the surface over a considerable zone; its lower part maintains the characters exhibited farther southward, as shown by excellent outcrops at many points on the Potomac river, and in ravines and railway cuttings to the westward ; and the superjacent clays progressively increase in thickness with- out material change in character. On Occoquan river quartzite the Middle Atlantic Slope. 129 pebbles, which are absent southward nearly to the James, again appear, and at Pohick creek become an important element in the formation ; while the leaf impressions so abundant to the southward disappear. About Washington the formation comprises two members sometimes discriminated with difficulty but apparently uncon- formable, the lower consisting of friable arkose or more hete- rogeneous sandstone, with lenticular partings and intercalated beds of clay and notable accumulations of quarzite pebbles (which in the westernmost outcrops become respectable bowl]- ders), and the upper consisting of irregularly and discontinu- ously bedded clays, with occasional intercalated beds of sand and pebbles. The clays comprising the greater part of the upper member, like those intercalated within the lower, are of obseure or inconstant structure, variable in composition, and diverse in color: they are sometimes massive and again finely laminated, now silty and unctuous, again made up of flakes and pellets of kaolin, and elsewhere intermingled with sand and grit; they are commonly gray, whitish, or lead-colored, but again pure white, blue, black, pink, red, brown, purple, or mottled with part or all these colors, generally in soft and deli- cate tints. Silicified and lignitized wood and even lignitized stumps tz sitw occur in both members; but identifiable plant remains are not herefound. Both members are locally stained and cemented by ferruginous infiltrations. Isolated outliers, made up principally of well-rounded quartzite and vein-quartz pebbles up to six or eight inches in diameter, crown eminences on both sides of the Potomac river, some of those on the south occurring fully twenty miles west of the continuous formation boundary. In this latitude the formation generally constitutes the surface over a belt fully fifteen miles in with, from the Piedmont gneiss on the west to the overlapping Eocene beds on the east; but the eastern boundary cannot be accurately drawn by reason of the puzzling graduation into newer de- posits. sometimes filling ravines and sometimes covering con- siderable areas, made up of redeposited Potomac materials. Attention was called to the deposits of the formation at Wash- ington by W. B. Rogers in 1875.* Between Washington and Baltimore the upper division of the formation (the “Iron Ore Clays” of Tyson ft) forms the surface generally and is extensively exposed in the cuttings on ~ both railways and in the numerous workings from which dis- seminated nodules of carbonate of iron are extracted, and has recently yielded abundant dinosaurian remains; and at Balti- * Proc. Bost. Soc. Nat. Hist., vol. xviii, 1875. + lst Rep. State Agricultural Chemist of Md., 1860, 30, 42. Am. Jour. Sct.—THirp SERIES, Vou. XXXV, No. 206.—Fes., 1888. 8 130 W. J. MeGee—Three Formations of more, as well as on the Patuxent and Patapsco rivers and their tributaries, the lower division is exposed and occasionally yields plant remains closely allied to those found in Virginia. Both members of the formation appear in the precipitous shores of the head of Chesapeake bay, the sandstone only on the north, but the white, blue, purple and varigated clays on both east and west ; and along Sassafras river these clays are unconformably overlain by the pyritous clays and greensands of the Maryland Cretaceous. Identifiable fossils have not been found in the sandstone member at this locality; but a few plant remains were found in the clays. The magnificent ex- posures of both the Potomac and Columbia formations here are described in detail and fully illustrated elsewhere.* Extensive outliers of gravel occur on both sides of the Sus- quehanna several miles from the body of the formation, notably at Webster on the south and Woodlawn (or Battle Swamp) on the north of the river. In extreme northeastern Maryland and in northern Dela- ware the sandstone member of the formation is not exposed as a continuous body, though it is represented by occasional iso- lated outliers of gravel upon the marginal Piedmont hills; but the superjacent clays appear in a number of localities, and form the subterrane over a considerable zone parallel with the Pied- mont escarpment. They have been studied by Chester, who designates them ‘“ Plastic Clays,” and refers them to the “ Lower Cretaceous (Wealdon ?).”+ So between the Rappahannock and the Brandywine the for- mation is a continuous terrane, consisting of a series of clays reposing perhaps unconformably upon a series of sands and gravels, while outliers of the inferior division crown the crests of the Piedmont plateau many miles from the main body; but northward it contracts and is again represented only by isolated remnants and exposures. In southeastern Pennsylvania both members of the forma- tion have been recognized by different geologists and have been variously classed. Clays apparently representing the upper member occur in the northeastern part ot Philadelphia county where they have been referred to the Wealden ;t+ the gravelly outliers representing the lower member in the vicinity of Phil- adelphia have been designated the “ Bryn Mawr Gravel” (from a locality of typical outcrop) and referred to the Tertiary by Lewis;§ and similar exposures in Delaware county have been * “ Notes on the Geology of the Head of the Chesapeake Bay,” 7th Ann. Rep. U. S. Geol. Survey (in press). 7 + Proc. Acad. Nat. Sci., 1884, 250-1. ¢2nd Geol. Surv. Pa., Report X, Hand Atlas of Pa. J. P. Lesley, 1885, Plate 46. § Proc. Acad. Nat. Sei. Phil.. xxxii, 180, 269, 272; Ibid. 296, et seg.; Journ. Franklin Inst., xev, 1803, 371-73; and elsewhere. the Middle Atlantic Slope. 131 mapped by O. E. Hall, who designated the deposit ‘ Ferrugin- ous Conglomerate,” and followed Lewis in referring it to the -Tertiary.* The low-lying clays in the valley of the Delaware are not well exposed, have yielded no fossils, are not. known to be connected with the plastic clays of Délaware, and cannot be certainly correlated with the upper member of the formation ; but the gravelly outliers belong to a series traced from the Rappahannock river northward, everywhere sustaining identi- eal relations to the underlying rocks and to the topography, and everywhere petrographically similar to a characteristic phase of the formation as typically developed in Maryland and Virginia, and may be confidently correlated with the lower member. Indeed, in the exposure in Media the most abund- ant materials are characteristic kaolinic arkose and more hetero- geneous brown ferruginous sands such as occur about the head of Chesapeake bay, coarse gravel being but a subordinate ele- nent.t In the vicinity of the Susquehanna the gravel of the outliers is generally coarse and abundant; over the plateau be- tween that river and the Schuylkill it is finer and less abund- ant: and toward the latter stream it again grows coarse and the outliers become more conspicuous. North of the Schuylkill the lower member is typically de- veloped at several localities in Rose valley, in the northwestern part of the village of the same name. The deposit is an ob- scurely bedded arkose, generally friable but sometimes lithified, containing well worn quartz and quartzite pebbles both dissem- inated irregularly and in lines, together with pellets and flakes of clay, the whole similar to the deposits found in Virginia ; and silicified wood occurs in small quantities, but neither leaf- impressions nor the bands of clay in which they are commonly preserved were found. The mass is irregularly stratified and evidently undisturbed, and rests directly upon tilted Triassic sandstone. Again, three or four miles north of Conshohocken, extensive deposits of white, pink, and mottled plastic clay, petrographically indistinguishable from the upper member of the formation where typically developed, are found overlying gravelly arkose. The clay beds are largely worked for pottery, while the subjacent arkose is excavated and screened for build- ing sand and road metal—indeed there is a considerable area north of Conshohocken and Norristown in which the proxim- ity of the Potomac is proved by the presence of its materials in roadways and foot-paths, and in the mortar of houses and barns. Still farther northward outliers of gravel generally finer than that found in the vicinity of the Schuylkill occur, * 2nd Geol. Surv. Pa., Report U5, 1885, 10-13, and map. t +C. K. Hall notes pebbles 6 inches in diameter at this point; but so large peb- bles are probably rare, and were not found by the writer. 132 W. J. McGee—Three Hormations of as in the neighborhood of Broad Axe, near Three Tuns, three miles northeast of Hatboro, and indeed generally on the sub- ordinate divides and eminences northwest of Chestnut Hill and Edge Hilj. The gravel in these outliers is fine (seldom over an inch in diameter), well rounded, generally of quartzite, and commonly imbedded in a scant matrix of arkose. A compact pinkish quartzite is abundant and gives distinction to the gravel. The substantial continuity of the formation as represented by outliers is here broken, no exposures being known between the east-flowing tributaries of Neshamin creek (near Church- ville) and the Delaware river, a distance of nearly twenty miles ; but two miles above Trenton on the New Jersey side of the Delaware there is a distinctive deposit locally known as the “Yellow Rocks,” made up of arkose, sometimes lithified but generally friable, containing abundant well rounded (but fre- quently disintegrated) quartzite pebbles, disseminated, ar- ranged in lines, or acecumulatéd in pockets, together with pellets and flakes of white plastic clay. The deposit is ivregu- larly stratified and inclines northwestward, but at a consider- ably less angle than the immediately subjacent Triassic strata. No fossils were found in the beds, but they are petrographi- cally similar to those everywhere characteristic of the lower division of the Potomac formation, totally unlike those of the Triassic sandstones in structure, composition, and attitude, equally unlike the Raritan clays found in the vicinity, and quite distinct from the gravels and loams of the Columbia formation by which they : are overlain; and on the whole it seems evident that the deposit represents the sandstone mem- ber of the Potomac formation. Somewhat similar and prob- ably contemporaneous deposits of stratified sand occur two miles below Trenton beneath the Raritan clays. Midway between Princeton and New Brunswick, N. J., an anomalous and hitherto unclassified deposit of friable ferrugin- ous sandstone crowns the southernmost of the Triassie trap ridges, and is locally known as the “Sand Hills.”* It con- sists of massive or irregularly stratified and sometimes cross laminated brown sands, occasionally cemented by ferruginous infiltration, with a few intercalated lines of white or pinkish plastic clay, and is strikingly similar to the non-kaolinie sands of the Media outlier and of the body of the formation as ex- posed north of the head of Chesapeake Bay. This outlier is completely isolated and unfossiliferous; but it is distinct from the Triassic sandstone on both sides of the ridge in all diag- nostic features, and is, moreover, manifestly newer than the trap dike, which was itself formed after the sandstone was de- * Geology of N. J., 1868, 227, 342. the Middle Atlantic Slope. 133 posited. At the same time it is too unlike the well-defined Cretaceous and Tertiary formations found a few miles to the southeast to warrant correlation with, and is therefore evi- dently older than, any of these formations. In short, it appears to be a remnant of a formation largely removed by erosion before the later Cretaceous submergence, just as are the Poto- mac outliers in Virginia and Maryland; and on this indirect evidence of its chronology together with that of its petro- graphy it may be provisionally referred to the lower member of the Potomac, although nearly twenty miles from its nearest supposed, and thirty-five miles from its nearest known, homo- logue. It should be noted that the Raritan clays, which are perhaps equivalent to the superior member of the Potomac, and almost certainly newer than the sands and gravels of the two expo- sures just mentioned, are tentatively regarded as Jurassic by Whitfield.* Briefly, the Potomac formation consists of two perhaps un- conformable members, of which the upper is an inconstantly bedded and protean clay of variegated colors, either clean or sandy and pebbly, and the lower a generally friable sandstone, arkose, or gravel of irregular and inconstant structure. The - upper member extends from the Rappahannock at least to the Delaware and probably to the mouth of the Hudson, either forming or closely approaching the surface over a somewhat sinuous zone 275 miles long and only ten miles or less in maxi- mum width, overlooked throughout by the Piedmont escarp- ment. As a continuous terrane the lower member forms a still narrower zone flanking the Piedmont escarpment from the Appomattox to beyond the Susquehanna, and reappears in iso- lated exposures southward to the Roanoke and northward to beyond Delaware, over a total length of 300 miles; while as a series of insulated remnants crowning the hills of cireumdenu- dation toward the coastward margin of the Piedmont region it occurs occasionally from near the James certainly to the Dela- ware and probably to the Raritan, over a zone from five to forty miles in width. The tenuity of these zones of outcrop is but an accident of degradation and deposition. Studies about the head of Chesapeake Bay led to the conclusion that the former westward extension of the formation can be reliably inferred from the topographic configuration of the Piedmont region, the western part of which has a drainage evidently determined by lateral heterogeneity of the vertically-bedded terrane and a characteristic topography resulting therefrom, while the eastern * Brachiopoda and Lamellibrachiata of the Raritan Clays and Greensand Maris of N. J., Monog. U.S. Geol. Surv., ix, 1885 (Mem. Geol. Surv. N. J., 1885), 23. 134 W. J. McGee—Three Formations of part has a drainage independent of the varying obduracy of the terrane and therefore evidently superimposed by a forma- tion (which could only have been the Potomac) now generally removed by erosion ; this conclusion has since been verified by the discovery of isolated remnants of the Potomac formation on many parts of the area of supposed superimposed drainage ; and it may be confidently inferred from the configuration of the Piedmont plain that about half of its area north of the James River (but not much more than half) was submerged beneath the Potomac sea and at one time covered by its de- posits. A great extension of the formation eastward may also be inferred from the Fort Monroe boring, fifty miles from the nearest outcrops, in which undoubted Potomac deposits were found in considerable volume. The thickness of the forma- tion, either original or present, has not been accurately ascer- tained; the upper member must approach 3850 feet and the lower 250 feet near Baltimore and Acquia creek respectively, from which points both attenuate gradually, giving an agere- gate (the maxima being nearly 100 miles apart) of perhaps 500 feet; and while the loss by erosion at the localities of maxim thickness has not been great, it cannot be readily evaluated. Stratigraphic Felations.—South of the James river, the - Potomac deposits rest upon an irregularly eroded and some- times deeply ravined surface of highly inclined erystalline rocks, the inequality in altitude of the base within a mile on the same meridian (the formation and its subsurface having a considerable eastward inclination) reaching 100 feet or more. On that river the formation rests upon the irregular surface of the Richmond granite at the “fall-line,’ and upon the trun- cated edges of highly tilted gneisses and schists down the river for 20 or 80 miles; while to the westward outlying gravel patches repose unconformably on the tilted and faulted Rheetic* beds forming the Richmond coal field. Near Han- over Junction, the upturned Piedmont erystallines and the faulted, tilted, and diked strata of the Rheetic are alike overlain by the Potomac arkose which fills deep ravines in, and conceals irregularities of, the subjacent surface; and thence northward to the river from which they take their name, the Potomae sandstones repose unconformably upon irrecularly eroded surfaces of gneiss, except at Drainesville (25 miles west of Washington), where a gravelly outlier rests on the planed edges of tilted Triassic sandstones. At Washington the in- equality in altitude of the base of the formation, which evi- dently filled the valley of the Mesozoic progenitor of the Po- * Fontaine, ‘‘ Older Mesozoic Flora of Virginia,” Monog. U.S. Geol. Surv., VI 1883, 2, 96, 128. the Middle Atlantic Slope. 135 tomae river, is fully 200 feet within a mile and a half. North of the Potomac river, the deposits, both in the main body and in the outliers, generally repose upon the eroded surface of the Piedmont crystallines, the depth of local ravining reaching some 250 feet about the mouth of the Susquehanna and _ pro- portionately less depths on the smaller streams; but the great outlier north of the Schuylkill in Pennsylvania, which exhib- its all of the characteristics of the main body of the formation, rests in part upon crystallines, in part upon folded Silurian limestones, shales, and quartzites, and in part upon degraded Triassic sandstones and shales. On the Delaware the “ Yellow Rocks,” believed to represent the formation, rest upon a planed . surface of tilted Triassic sandstone and highly inclined gneiss ; and the still more doubtfully identified outlier forming the “Sand Hills” near the Raritan, rests upon an apparently eroded Triassic trap dike. In short, the formation everywhere reposes on a deeply degraded surface of upturned Piedmont -crystal- lines, folded Silurian strata, tilted, faulted, and diked Triassic sandstones, and diked and displaced Rheetic beds; and it is significant that this surface is a generally uniform plain, in- clined seaward and deeply incised by great waterways, coin- ciding closely with those of the present. South of the Rappahannock the Potomac formation is over- lain by the Appomattox formation, the fossiliferous Miocene, and the Kocene ; between the Rappahannock and the Patapsco it is overlain by the Eocene; north of the Patapsco it is over- lain so far as known by the upper Cretaceous; and in the ab- scence of these, and up to certain altitudes indicated later, it is overlain by the Columbia formation; the relation gener- ally, but not invariably, being one of visible unconformity. The unconformity between the Columbia and the Potomac is well exhibited in representative sections at Fredericksburg, Wash- ington, Baltimore, and the head of Chesapeake bay, but over the interfluvial plains and on certain slopes about Washington the formations, though widely diverse in age, intergraduate so imperceptibly that it is impossible to demark them; there is notable unconformity between the Appomattox and Potomac formations on the Roanoke and in some sections on the Appo- mattox and James rivers, but in other sections on the last named rivers (at Fredericksburg and elsewhere), there are de- posits of composite character certainly belonging to one or both ot these formations which cannot be discriminated even in the same section; the Miocene rests on the Potomac in the local absence of the Eocene at Petersburg and Richmond, but no noteworthy unconformities have been observed; the Eocene is unconformable to the Potomac on the Nottoway and generally about Richmond, and notably in a railway cutting near Brooke 136 W. J. MceGee—Three Formations of (where two deep ravines in the Potomac are filled with fossil- iferous Hocene deposits), though in some sections at Richmond the two cannot be discriminated, and at Good Hope Hill, near Washington, Eocene fossils occur in deposits made up of Potomac materials supposed to be i s¢tw before the discovery of the fossils; and on Sassafras river there is a marked uncon- formity between the pyritous clays and greensands of the upper Cretaceous and the subjacent Potomac clays, while in the best section about the head of Chesapeake bay (Maulden’s Mountain) the sequence from massive Cretaceous greensand above to iron-bearing Potomac clay below is unbroken save by arbitrary lines. In short, it is evident that the Potomac ter- rane has ever Jain near sea-level, and has alternately suffered less by denudation and accretion by sedimentation during oft- repeated oscillations, has been deeply ravined during one epoch only to have the ravines filled largely with its own materials but with some foreign matter and more recent fossils during the next, and has contributed material to each newer formation of the Coastal plain. Its characteristic pebbles have indeed been successively transferred to the newer Mesozoic beds, to several of the Cenozoies, and finally incorporated in the Quaternary. There is an apparent unconformity between the two mem- bers of the Potomac, marked. by beds and pockets of gravel superimposed upon erosion planes, as In a, noteworthy section three miles southeast of Washington ; but since local unconfor- mities, including both erosion planes and accumulations of gravel and bowlders, occur at various horizons in each member, there is some doubt as to the importance of this apparent un- conformity. Fossils.—Until recently animal remains were believed to be exceedingly rare in the formation: fragments of a rib of a cetacean and part of the teeth and bones of a reptile supposed to be related to the Iguanodon are recorded by Tyson from the upper member in Maryland,* the latter being the Astrodon Johnstonii of Leidy;+ six undescribed species of the fresh water genera Unio and Anodonta and several “ ctenoid fish scales” associated with “leaves of dicotyledonous trees” are noted from the upper member in western New Jersey, and identical Unzos “from the banks of the Potemac” by Cope;t Conrad described from the plastic clays of New Jersey (which are either equivalent to or newer than the upper division of the Potomac formation, but which he regarded as Triassic), two lamellibranchiates, Astarte veta, and A. annosa;$ and * First Report Maryland Agricultural Chemist, 1860, 42; cf. Uhler, Johns Hop- kins University Circulars, vol. ii, No. 21, 1883, 53. + Cretaceous Reptiles of the U. S., Smithsonian Contributions to Knowledge, vol. xiv, 1865, 102. t Proc. Acad. Nat. Sci., xx. 1868, 157. § Am. Jour. Conch., iv, 1868, 279. the Middle Atlantic Slope. 137 Whitfield has more recently recognized from the same clays (which he, too, is disposed to refer to the Triassic) five lamel- libranchiates—A starte veta, Ambonicardia Cookii, Corbicula emacerata, Corbicula annosa (Conrad’s Astarte annosa), and Gnathodon tenuides.* In the course of an examination of the formation extending over some years, Fontaine has found but a single animal fossil, viz: the posterior portion of a homo- cereal fish about the size of a salmon from the lower mem- ber on James river. Careful search during the past three months has led to the discovery of moderately abundant dino- saurian remains of upper Jurassic type and the upper member between Washington and Baltimore, some of which have al- ready been described by Marsh.t At-several points on the Appomattox and James rivers, on both Anna rivers, about Iredericksburg, on Acquia creek, at Baltimore, and at a number of other localities the laminated beds of clay intercalated within the lower member yield abun- dant and well preserved leaf impressions; and throughout the whole extent of the formation both members abound in silici- fied and lignitized wood. Fontaine has collected and investi- gated the plant remains, and has just sent to press a monograph containing descriptions of over 870 species, of which more than 300 are new. Extensive collections of silicified and lignitized wood have also been made from both members and have been investigated by Knowlton; and eight new species belonging to two new genera have been discriminated and are described and illustrated in a memoir now in press.t Viewed as a whole, the Potomac flora is unique. It is, moreover, of special interest in that it records a stage in the de- velopment of plant life not known to be represented elsewhere on the globe. The plant history of the earth falls naturally into two eons, instead of the three represented by animal life, during the first of which the various non-dicotyledonous forms (the cryptogams, cycads, conifers, and monocotyledons) of archaic type prevailed, while throughout the second dicotyle- donous forms of modern type have greatly predominated,—the transition from the archaic to the modern type being sudden, and the bipartite division being consequently stronger and more trenchant than the tripartite division based chiefly on animal remains. Now the exact period of transition from the archaic flora to the modern one (hitherto placed about the middle of the Cretaceous)§ appears to be represented in the Potomac flora; there is a commingling of primitive and recent types in nearly every plant bearing clay bed; the types * Monog. U.S. Geol. Surv., vol. ix, 1886, 23-27. + This Journal, xxxv, 1888, 89-94. ¢ Bulletin U.S. Geol. Surv. (in press). § Ward, 5th Ann. Rep. U.S. Geol. Survey, 1885, Plate lvi. 138 W. J. McGee—Three Formations of are about equally represented in the entire section; and the transition is recorded not only in the commingling of types but in a measure by the assumption of modern external forms while the plants yet retained the archaic internal structure. It is significant that well preserved leaf impressions are not found in the formation about Washington, in the lower mem- ber at the head of Chesapeake bay, in the deposits near the Schuylkill, in the “ Yellow Rocks” at Trenton, nor in the im- mediate vicinity of Richmond—the plant-bearing localities on the James being several miles from the fall-line,—i. e., about the mouths of the Mesozoic prototypes of the great rivers of the region. Taxonomy.—The general facies of the wonderfully rich flora most closely approaches that of the middle and lower Neocomian of Greenland and Europe, and Fontaine is disposed to refer the formation to the lower Oretaceous on this evi- dence; but since the flora is manifestly too nearly unique to permit precise correlation, and since Marsh finds the verte- brate remains to be distinctly upper Jurassic, the formation must be at least provisionally assigned to the latter period. The Tuscaloosa formation of Alabama appears to be the precise equivalent of the Potomac;* and Hill has recently col- lected data indicating that the Trinity formation (Dinosaur Sand)+ of Texas and Arkansas is coeval with the Potomac and Tuscaloosa. Sources of Materials.—Roughly classified, the materials of the Potomac formation are (1) quartzite pebbles, (2) quartz - pebbles, (8) arkose, (4) quartzose sand, (5) plastic clay, and (6) various combinations of these. 1. The distribution of the quartzite pebbles is significant : They are abundant and large on James river but diminish rap- idly both in abundance and size about to the Appomattox on the south and the South Anna on the north, where they finally disappear—none occurring on the Nottoway or Roanoke, nor on the North Anna, the Rappahannock, or the intermediate smalier streams. They reappear near the Occoquan, and in- crease rapidly in abundance and size to the Potomae, where they form a predominant element in parts of the formation ; but they again diminish in size and abundance northward, be- coming inconspicuous north of Baltimore, to once more increase in size and number about the Susquehanna, where the outliers consist almost exclusively of well rounded quartzite pebbles and bowlders. North of the Susquehanna like relations obtain, so far as size is concerned, the pebbles gradually diminishing in size over the Susquehanna-Schuylkill divide, enlarging * Bulletin U. S. Geol. Survey, No. 43. + American Naturalist, vol. xxi, 1887, 172. t Science, vol. xi, 1888. the Middle Atlantic Slope. 139 again about the Schuylkill, once more decreasing in size in the outliers lodged behind Chestnut hill and Edge hill, and again assuming considerable dimensions on the Delaware; but in this part of the area of the formation the quartzite pebbles occur on the smaller streams and over the divides as well as on the great rivers. J inally, in the Sand Hills quartzite is nearly or entirely absent. In short, the quartzite pebbles occur only in the vicinity of those rivers which flow through the quartzites of the Appalachian and upper Piedmont regions, and their abun- dance and size vary with the dimensions of the rivers and the proximity of the ridges. The composition of the pebbles is equally significant: Those found about Washington and Richmond sometimes exhibit Scolithus borings and easts of brachiopods, ete., identical with those found zm setw in the axial quartzites of the Blue Ridge and adjacent Appalachian ranges in their less metamorphosed portions ; the pink quartzite of the pebbles found over the Schuylkill-Delaware divide is in all respects similar to that of certain exceptionally obdurate ledges in the quartzitic axes of the low ranges here encroaching upon the Piedmont region ; and the distinctive pebbles are in both these as well as in other cases confined either to the vicinity of the distinctive ledges or to the lower reaches of the rivers transecting them. So by distribution and composition, the quartzite pebbles of the Potomac formation may be-traced to their parent ledges in the Appalachians ; and their distribution indicates at the same time the ancient river-courses and the shore lines along which they were transported. 2. The quartz of the second class of pebbles (which some- times assume the dimensions of respectable bowlders) is petro- graphically identical with the vein quartz everywhere inter- secting the Piedmont crystallines ; the pebbles, like those of quartzite, are generally largest in the greater valleys and to- ward the western margin of the formation, though considerable bowlders occasionally occur in all parts of it; they are most abundant where the quartz veins are large and numerous ; and local peculiarities in the vein quartz are reflected in the lee- ward pebbles. It is evident, in short, that the pebbles are de- rived from adjacent veins. Indeed in a section in the north- western part of Washington a train of fragments of a quartz vein intersecting the Archean gneiss and projecting into the superjacent Potomac gravels, is traceable in the gravels for some distance before the fragments so far lose their angles as to become undistinguishable from the neighboring erratic pebbles. 3. The arkose is made up of angular grains of quartz, crys- tals of feldspar or flakes of kaolin, scales of mica, ete., the 140 W. SJ. McGee—Three Formations of whole sometimes so similar to disintegrated granite or gneiss as to be distinguished only with difficulty. It reaches its best development toward the base of the formation, and especially in the smaller valleys and ravines or on the subjacent gneissic surface; and it is not found in: perfection along the lines of the larger rivers. Its petrography and distribution alike justify the inference that it is granitic debris, not far transported. 4, By far the larger part of the quartzose sand, whether in homogeneous beds or intermingled with other constituents of the formation, consists of rounded quartz grains of doubtful origin, but evidently worn by transportation; a smaller part consists of angular quartz grains and flakes such as might be produced by impact of masses during transportation; a yet smaller part is made up of rudely crystalline grains such as re- sult from the disintegration of vein quartz; and the least im- portant element in volume, though it is locally conspicuous and significant, consists of more or less perfect crystals of quartz such as might form the residue of disintegrated granite after the solution and removal of the less obdurate constituents. All of these sources are doubtless represented in the sands of the Potomac. 5. The clay oceurs in minute flakes (sometimes of crystalline form) in the arkose, in rounded and irregular pellets and balls up to an inch or more in diameter in the arkose and sand beds, in lenticular or sometimes continuous bands intercalated with sand, and again in considerable beds exhibiting more or less definite structure planes; but whenever pure it is‘clean, plastic, kaolin-like, and evidently derived from a common source, and the smaller flakes retain the shapes of feldspar crystals undis- tinguishable from those of the adjacent Piedmont gneisses. The clay in the larger masses it is true appears to be thoroughly triturated, and was evidently deposited in finely divided con- dition ; and the pellets and balls appear to have been washed from such beds and redeposited in conjunction with other materials; but the structural differences between the pseudo- erystalline and the water-laid phases of the clay are no greater than would inevitably result from the trituration and assort- ment accompanying the breaking up of gneiss or arkose and the separation of the materials of unlike specific gravity and solubility. 6. The heterogeneous and ever varying accumulations of composite character which constitute the larger part of the for- mation are, qualitatively, just such as would be formed by the assortment and deposition of the different materials by power- ful currents; but the quantity of coarse materials in the Poto- mac formation is greater than would result from simple admix- ture of the disintegrated gneiss of the Piedmont zone and such the Middle Atlantic Slope. 141 proportion of Blue Ridge quartzite, vein quartz, etc., as appear to be mingled with it, suggesting that the portions of the for- mation now exposed were littoral, and that the finer materials were swept into deeper off-shore waters. The History recorded in the Formation.—The conditions of deposition of the lower member of the Potomac formation may be inferred from its structure and composition : the coarseness of the predominant materials is proof of the prevalence of pow- erful currents or violent waves; the local accumulations of arkose and of finely laminated clay are indicative of quiescent periods, of slack-water eddies, or of sheltered spots on a stormy coast; the frequent alternation of coarse and fine deposits, the broken up and re-deposited clay beds, and the local unconformities, all suggest repeated alternations of slack water and strong currents throughout the area of deposition; the distribution of the quartzite pebbles proves that this material was brought down from the easternmost Appalachian mountains by rivers coinci- dent with the great rivers of to-day, and the unequal altitude of the base of the formation along the rivers and the prevalent coarseness and inconstant structure of the deposits there indi- cate that the ancient rivers embouched into deep turbulent estuaries, while the interosculation of some of the estuarine deltas and the coarseness of the deposit connecting others prove violent wave action along the intermediate shore; the dearth of remains of marine and estuarine animals is suggestive of turbulent waters; and the peculiar distribution and _preser- vation of the plant remains suggests encroachment of the Potomac ocean upon lands covered with a luxuriant flora. The conditions of deposition of the upper member appear to have been similar but quieter. ' From the relations of the formation to the foundation upon which it rests, from structure and composition and indirectly from the conditions of deposition indicated thereby, the physio- graphic conditions attending the deposition of the Potomac formation may be inferred: The surface upon which the de- posits rest is formed of dislocated strata of Archean, Cambrian, Silurian, Triassic and Rheetic age, all degraded to a plain as uniform as the Piedmont zone of to-day—a plain destitute of noteworthy eminences despite the great heterogeneity of the rocks, and one which accordingly must have been reduced to base level; yet the unequal altitude of the deposits about the waterways indicate that this plain was ravined as deeply as is the present Piedmont plain; and the slight sinuosity of the shore line, despite the depth of the ravines, is proof of pro- nounced seaward inclination of the surface. Thus the structure, composition, and stratigraphic relations of 142 W. J. McGee—Formations of Middle Atlantic Slope. the Potomac formation, when freely interpreted, give the out- lines of an intelligible and harmonious picture of the Atlantic slope during and for some time antecedent to the Potomac pe- riod: Before the initiation of Potomac deposition, but subse- quent to the accumulation of the Triassic and Rheetic deposits and to the displacement and diking by which they are affected, there was an eon of degradation during which a grand moun- tain system was obliterated and its base reduced to a plain which, as its topography tells us, was slightly inclined seaward and little elevated above tide—the Piedmont zone alike of the later Mesozoic and the present; and over this plain meandered the prototypes of the Delaware, the Susquehanna, the Potomac, the James, and the Roanoke, within a few miles at most of their present courses and but a few hundred feet above their present channels, flowing slack and in shallow valleys because at base level. There followed a slight elevation of the land, when the rivers attacked their beds and excavated valleys as deep as those to-day intersecting the Piedmont plain; but whether or not there was concomitant tilting of the land, the phenomena thus far fail to indicate. Then came the movement by which the deposition of the Potomac formation was initiated—the deeply ravined base level plain was at the same time submerged and tilted oceanward ; its waterways became deep but short estuaries; deep oceanic waters extended quite to the inter- mediate shores; the declivity and transporting power of the rivers was increased; and the accumulation of coarse delta and littoral deposits progressed rapidly. With continued deposition the sea gradually shoaled, the declivity of the land decreased, the materials became finer and finer; there was probably temporary emergence of the land about the middle of the Potomac period, followed by renewed submergence without seaward tilting during which the clays of the upper member were laid down; and the period was finally closed by an emergence represented by the unconformity between the upper Potomac and the glauconitic deposits of the Maryland Cretaceous. There is a great hiatus in the geologic history of the Atlantic slope: The history is fairly legible up to the ter- mination of the Paleozoic deposition, and it is even more clearly legible from mid-Cretaceous time to the present ; but the hiatus includes the most interesting period in the evolution of the eastern portion of the continent. The transfer of sea and land: the elevation and corrugation of the Appalachians, and the profound displacement and metamorphism of the Piedmont rocks; the degradation of thousands of feet if not miles of strata and the transportation of the materials whither no man J. H. Pratt, Jr.—Capdlary Electrometer. 143 knows; the deposition of the Triassic and Rheetic rocks under conditions which no geologist has ever clearly pictured in im- agination—at least to the satisfaction of his fellow geologists; the Triassic displacements and diking; the post-Triassic degra- dation of thousands of feet of strata and the removal of the debris to other regions—these and many other remarkable epi- sodes have been completely blotted out of the geologic record as commonly interpreted. But the Potomac formation nar- rows the hiatus: the formation itself carries the record back from mid-Cretaceous time to the earliest dawn of the Cre- taceous or the closing episodes of the Jurassic; and the post-Rheetic and pre-Potomac degradation will tell the story of the Jurassic as eloquently, when men have come to read geologic history in erosion as well as in deposition, as if the deposits of the period were exposed to observation instead of lying beneath the thousands of feet of newer strata forming the Atlantic bottom. So while the hiatus is not yet closed it is reduced by a fifth, a fourth, or perhaps a third of its length. Art. XIIl.—LHaperiments with the Capillary Electrometer of Lippmann ;* by JuLIus Howarp Pratt, JR. THE objects of this investigation have been, first, to determine the limits within which the given form of electrometer can be used ; secondly, to ascertain whether the polarization of the mercury surface is such as to prevent the passage of a current while the instrument is in use; and, thirdly, to determine the amount of charge retained at the polarization surfaces when the mercury column is in equilibrium. The instrument used in these experiments was constructed as follows: V isa thistle tube, the tubing of which (A B) was bent in the manner indicated (fig. 1); G is a small glass vessel * Abstract of a thesis presented for the degree of Doctor of Philosophy at Yale University, June, 1887. 144 J. H. Pratt, Jr—Capillary Electrometer. containing mercury and dilute sulphuric acid; @ and # are platinum wires which serve as conductors for the electric cur- rent. ‘They pass through the glass tubes in vessels G and V, and are fused into the tubes at the end; the platinum elec. trodes, accordingly, have only a small area. The end of A B itself is filled with sulphuric acid to M, the mercury meniscus. S is aleveling screw. The whole is mounted on a wooden base to give it stability. C Disa millimeter scale on which the readings are made. For most of the work done the unaided eye, or a small magnifying glass was sufficient to make the readings,—as the differences of deflection for slight differences in E. M. F. were comparatively great. For instance, the difference of deflection between -02 Daniell and -03 Daniell was, for a given adjust- ment, 2°4 millimeters ; hence, 1™™ (which can easily be read) showed a difference of about -0004 Daniell, For the experl- ments in quantity of electricity a micrometer was used, by which readings could easily be made to 5},"™ with accuracy. IE Lippmann states * that the value of the capillary con- stant in his instrument increases for increasing potentials to about ‘9 Dan. and then diminishes. The same results are ob- tained with the form here given. 2. Two Daniell’s cells are connected as shown in figure 2. Risa resistance-box of 10,000 ohms, through which the cur- rent passes. By the wires a and , fractions of the current are made to pass through the electrometer. The accompanying table and plot (No. I, fig. 4) will exhibit the results. Column I gives the fraction of the E. M. F. of a Daniell cell which pro- duces the deflections given in column II. TaBLE I.—March 1, 1887. E.M.F. Defiect. E.M.F. Defiect. E. M. F. Defiect. E.M. F. Defiect ~ 008s) ark eee 16 Dan. 28°2™™ °60 Dan. 77:4™™ 1°2 Dan. 80™™ “016 23 “20 34:7 “80 88:0 1°4 64 “04 (2 *30 49°5 *892 $0°3 1°6 50:2 “08 14°5 “40 60°7 1:0 89-0 1°8 42°5 In taking the deflections for the higher.of these potentials 1:2 to 1°8, electrolytic action was noticed and bubbles of gas * Annales de Chim. et de Phys., Ser. V, vol. v; E. Mascart, Traité d’ Electricité Stat., ii, p. 550. J. H. Pratt—Capillary Plectrometer. 145 formed on the mereury surface. It is necessary in all these investigations that the current pass in such a way as to produce hydrogen polarization. Oxygen polarization does not change the capillary constant in any regular manner. Moreover the use of even comparatively low potentials with oxygen polariza- tion causes chemical action so that the surface of the mercury is fouled, which seriously interferes with the action of the in- strument. ‘Two series of deflections of the meniscus for given electro-motive forces were made. In one series hydrogen po- larization was used, and in the other, oxygen. The series with hydrogen polarization, was regular, as before ; but that of oxy- gen, except for very low potentials, was so irregular that no conclusions could be drawn. Apparently the position of the meniscus depended largely on the chemical action caused by the current. In using Lippmann’s electrometer it might be convenient to dispense with the mercury contact and employ only sulphuric acid and platinum. A set of observations was accordingly taken, in which the mercury was removed from the vessel G and the platinum wire served as electrode. The surface of the platinum in contact with the sulphuric acid being so small, it was found that, owing to polarization of the platinum-sulphurie acid surface, a given potential would produce a deflection only a fraction of that produced with mercury as electrode. With the platinum electrode the maximum point on the curve was for potential about 1:5 Dan. instead of 0-9 Dan. as was the case with the mercury electrode. The small capacity of the plat- inum electrode will sufficiently account for this. If, then, plat- inum electrodes be used in place of mercury, care should be taken to have their capacity great compared with the capacity of the mercury meniscus. It should be noted, then, that, in actual use, Lippmann’s electrometer makes a good means of measuring low potentials, up to 0°6 or 0-7 Dan.; that care must be taken to avoid oxygen polarization and employ hydrogen polarization only; that the inner surface of the glass tube should be kept free from dust and traces of acid, which occasion irregularities in the deflec- tion of the mercury. The instrument in this form can be used to advantage for comparing E. M. F. of different batteries. Only a part (a known fraction) of the current should be used; as, Otherwise, the limits of the instrument might be exceeded. By using a micrometer for reading deflections, about 354>> Daniell’s cell E. M. F. can be detected. The electrometer might be used successfully in many cases for a galvanometer, especially where it is desirable not to alter the main current by a derived galvanometer circuit. It may be recommended for Am. Jour. Sct.—Tuirp Series, Vor. XXXV, No. 206.—FEB., 1888. 9 146 J. H. Pratt—Capillary Electrometer. such service, first on account of its comparative rapidity in coming to a state of equilibrium; secondly, because it is prac- tically a dead-beat instrument ; and, thirdly, because the read- ings may be made directly, and show immediately their rela- tion to E. M. F. The ease with which the instrument is con- structed puts it within reach of all who have some ability in glass-blowing. Il. Zo ascertain whether a current passes when the mercury surface is polarized. For this purpose the instrument was connected as before, and, in addition, a reflecting galvanometer and a key were placed in the branch with the electrometer. The deflections were observed by means of a telescope and millimeter scale about four feet from the galvanometer. It was easy to detect a deflection amounting to 0°1™" which, for the distance of the pe enonee from the scale meant an exceedingly minute de- ection ; and hence an insignificant current. The arrangement can be seen from figure 3. B is the battery of two Dan- iell’s cells. R is a resistance-box of 10,000 ohms. Eis the electrometer; K, the key; and G, the galvanometer. The current from the battery was passed through the resist- ance-box. Known fractions of this current made the cireuit through the. electrometer and galvanometer. Before the mer- cury reached the position of equilibrium, there was evidence of a current through the galvanometer; but when once the mercury came to rest, the deflections of the galvanometer ceased. This was true for low potentials and until the E. M. F. reached about 1-4 Dan. Plot II. and Table IL. given below, will show the results obtained for hydrogen polarization. The first column gives the potential of the current passed through the galvanometer, and the second gives the final deflection of the galvanometer needle, measured in scale divisions (™™) and indicating the strength of the current through the galvanom- eter. J. H. Pratt—Capillary EHlectrometer. 147 TaBLE IJ.—March 22, 1887. E. M.F. Defiect. E.M.F. Defiect. £.M.F. Defiect. -01 Dan. 0 -40 Dan. 0 1:41 Dan. WAV 02 oy [psstes “60 ci etien 1:42 2.0mm “04 0 “80 0 1°50 BA) -08 0 “90 0 1°60 erm 10 2 1:00 0 1°80 NBA 20 0 1°40 *pmm The deflections obtained for the E. M. F. 0:02 D., and 0-1 D. 0-6 D. are evidently accidental. Neglecting these, it is evident that no appreciable current passes through the electrometer until the potential of its surface reaches 1-4 Daniell. This, it will be remembered, is not the highest point of the curve show- ing the deflection of the mereur y in the electrometer. That point is reached when the potential of the mercury surface is 0°9 Daniell. The point at which conduction begins is about the point at which electrolysis begins. The collection of gas bub- bles (before mentioned), when potentials of something over one volt were used, indicate that electrolysis actually does take place. The results of this investigation will prove that con- duction through the electrometer begins about the same time. On April 1, 1887, a series of measurements was taken to de- termine the exact point at which conduction begins. In this series, before each observation, the sulphuric acid was run 148 J. A. Pratt—Capillary Electrometer. through the tube to cleanse the surface; and the bubbles of gas, if any, were driven from the tube. The arrangement of the instrument was the same as before, and the readings were taken with great care. TaBLE III.—April 1, 1887. EK. M. F. Deflect. E.M. F. Deflect. E.M.F. Detlect. 1:20 Dan. 0 1°32 Dan. "25 mm 144 Dan. - 1:30 ™™ 1-21 0 1°34 330) 1°50 2°30 1°22 705 mm 1:36 “45 1°60 6:70 1°24 10 1-38 155) 170 12°90 1:26 O15) 1:40 “60 1°80 21:20 1:30 -20 1°42 1:20 Since in a Daniell’s cell the replacement of one gram-equiva- lent of zine evolves 24,200 cal. of heat; and, when one gram of hydrogen and 8 grams of oxygen unite to form. one gram- equivalent of water, 32,462 cal. of heat are evolved,* therefore a cell of potential 32462 Dan. (equals 1:34 Dan.) would be just sufficient to decompose water. For about this potential (1°34 ' Dan.) it might be supposed that conduction through the elec- trometer would take place. Molecular changes which accom- pany electrolytic action may, very probably, slightly precede it and cause variations in the electrical conditions which allow a current to pass. If, moreover, there were any leakage in the instrument, this would be evidenced by a current through the galvanometer, when the potential was below 1°34 Dan. De- fective insulation would cause leakage, and conduction would begin at a somewhat lower potential. It will be seen by re- ference to the table that conduction begins not far below the electrolytic limit, i.e., at 1°22 Daniell; and that, at first slowly and then rapidly, it increases with the potential. When the mercury was treated with oxygen polarization, conduction began at very low potentials. An E. M. F. of 0-01 D. gives a permanent deflection of 6™™; and other higher potentials gave higher deflections; which, however, seem to follow no uniform law. This, like the former experiments with oxygen polarization, shows that such polarization cannot be too carefully avoided. Ill. Yo determine the capacity of the ebectrometer.—Three methods of making this determination were tried. The nature of the instrument makes it impossible to secure rigorously accurate results. However, several not inconsistent values of the instrument’s capacity were secured, and the final determina- tions should be regarded as fair approximations. By the first method a condenser of one microfarad capacity was charged with electricity at a known potential (V), and the charge was * Daniell’s Physics, p. 609. London, 1885. J. H. Pratt—Capillary Electrometer. 149 then passed through the electrometer and the deflection noted. By reference to the E. M. F. curve for the electrometer the potential (V’) for the given deflection was found. The electric- ity being divided between the two instruments the proportion will hold V : V’::C+C’ : C, where V equals the potential of the condenser, V’ equals the potential of the electrometer, and C and C’ the capacities of each. By division, V—V’ : V’::C’ 5 (Chor ao As V’ is found to be small compared \ with V, the equation C=—0 will be approximately true. This method has some disadvantages which make it impracticable for accurate results. The discharge from the condenser being practically instantaneous, its full force is exerted at once on the mercury, the inertia of which is apt to carry it beyond the position to which an equal amount of electricity, in the ordinary use of the instrument, would bring it. On the other hand, the tendency of the electrometer to dis- charge itself acts in the opposite direction and prevents the ex- act determination of the deflection. The results from this method cannot be accepted as satisfactory. The only safe conclusion is that the capacity of the electrometer is great com- pared with that of the condenser. © By the second method employed, the condenser and electrom- eter were placed in the same circuit, and the current passed through both in series. The ratio of the E. M. F. of the cur- rent to the potential indicated by the deflection of the electrom- eter gives the capacity of the electrometer compared with that of the condenser. The self-discharge of the instrument acted very disadvantageously. When the current, passing through the electrometer, had charged the condenser, the latter acted like an infinite resistance in the circuit, and the mercury of the electrometer, instead of remaining at the point to which | it had been deflected, moved from it and gradually returned to zero. As the readings were made with a micrometer, and could not be taken immediately, this movement prevented accuracy. ‘The indication was, as in the other method, of a capacity far greater than that of the condenser. To secure more satisfactory results a third method, without condenser was resorted to. A resistance box of 250,000 ohms, of which 240,000 ohms were used, was put in circuit with the | electrometer, and currents of known potentials were passed through the two. As the passage of a definite amount of electri- city through the electrometer is necessary to bring the meniscus to a given position, the movement of the mereury was retarded by the introduction of the large resistance. The slow motion made it possible at any instant to determine the position of the 150 J. H. Pratt—Capillary Hlectrometer. meniscus. The deflections for equal successive intervals of time were thus obtained. Series were made for various E. M. F. from 0:2 D. to 1:0 D. with accordant results. The table and curve LV (fig. 4) will show the results when a current of 0:6 Dan. was used. With a large resistance in the circuit, the mercury never reaches the point to which a current of the same poten- tial with small resistance would bring it. The deflections of 0°6 Dan. without large resistance is 81". That found after thirty minutes passage of the current with resistance was 78™™. TABLE [V.— May, 1887. Defiect. Time. Defiect. Time. Deflect. Time. Defiect. Time. 24°8mm 1 min. 6oyZEa 5 min. 75°Qmm 9 min. 768mm 13 min. 43:0 2, 69°8 6 76:2 10 54:0 3 72:2 7 76°5 iat 61:0 4 74:0 8 76'8 12 Since the movement of the mercury is slow we may assume that, during the excursion of the mercury, the E. M. F. at the surface of polarization varies according to the curve of the potentials, and that at any instant the position of the meniscus determines the E. M. F. We have, thus, ameans of computing the capacity of the instrument for a given potential. By Ohm’s law I=5. Also C (capacity) == By reference to uv curve IV, it will be seen that a portion of the curve between any two points taken sufficiently near to each other will differ but shghtly from a straight line; hence the mean of the E. M. Forces at the beginning and end of any short interval of time will give the mean potential of that interval. If E, equals E. M. F. at the beginning of the first interval of time; E, that at the beginning of the second, ete., the capacity is represented by the equation t (E,+E, C=5( aL) yen g) 4. Bobo O16 ¢ +E.) 9 R is the inserted resistance plus the resistance of the electro- meter. The latter was found to be, approximately, 10,v00 ohms; so that R equals 250,000 ohms. The interval of time (¢) was 60 seconds Computation gives for potential 0-2 Dan., C equals 314 mfds.; 0:4 Dan., C equals 445 mfds.; 0°6 D., C equals 605 mfds.; 0-7 D., C equals 648 mfds.; 1:0 D., C equals 730 mfds. The values for the capacity are approximate and will apply only to the instrument in question. In this the radius equals 0°64"™ about, and hence the surface of the mercury, re- garded as hemispherical equals about 2°572 sq. mm. The radius of the tube*was found by measuring the length of a column of mercury (for the hemispherical shape of whose ends due allow- ance was made) in the tube, and weighing the mercury. From these two factors the radius of the tube was computed. H. Crew—Rotation of the Sun. 151 In regard, then, to the Lippmann’s Electrometer it has been shown : First, that, when hydrogen polarization is used, the deflections of the meniscus may be taken as proportional to the E. M. F. for very low potentials, and that for potentials up to 0-9 D. an empirical curve will show the relation between the E. M. F. and the deflection. Secondly, that polarization is complete, and that no appreciable current passes through the electrometer until it be charged to a potential near that at which electrolytic action begins. Thirdly, that the capacity of the Lippmann Electrometer is very considerable, compared, for example, with that of the Thomson Quadrant Electrometer, being in the particular instrument studied, several hundred microfarads. The investigation, of which a summary is given in the pre- ceding pages, was carried on at the Sloane Physical Laboratory of Yale University under the direction of Prof. A. W. Wright, to whom I would here express my grateful acknowl- edgment for his encouragement and advice. Cornell University, Ithaca, N. Y., November, 1887. Arr. XIIL—On the Period of the Rotation of the Sun as determined by the Spectroscope ; by HENRY CREW, Assistant in Physics, Johns Hopkins University. ' ZOLLNER* and Vogel were the first to measure the rotation of the sun by the use of Doppler’s principle. For this pur- pose, they employed the so-called ‘reversion spectroscope ” of the former. This had two prisms with their refracting edges turned in opposite directions, thus forming two spectra, side by side, in opposite directions, the one serving as a vernier for the other; any displacement of a line will be doubled, since the deviation in one spectrum is the opposite of that in the other. For their results, however, the authors claim little more than a qualitative value. Hastings,t+ two years later, by a very ingenious device com- pared the spectra of the center and the limb of the sun, but gave no quantitative observations on the displacement. of the lines which he observed in passing from one of these regions to the other. Langleyt has devised an instrument which gives, in juxtaposition, the spectra of light from any two points, distant 180° on the circumference of the solar dise. He has noted, in rather an incidental way, the displacement due to rotation of * Zolluer: Poge. Aun., cxiv, 449, 1871. + Hastings: this Journal, v, 369, 1873. _{ Langley: this Journal, xiv, 140, 1877. 152 HH. Crew—Rotation of the Sun. the sun, when examining an equatorial diameter, and the absence of any displacement when comparing the extremities of the polar diameter, and has also commented on this as a means of separating the solar and telluric lines. In 1876, Prof. Young* published the first accurate measure- ments of the linear velocity of a point on the solar surface. These were made with a spectroscope attached to a 94 inch equatorial, and fitted with a Rutherfurd grating, ruled with 8640 lines to the inch. His result is for a mean latitude of 7° and is reduced to the equator by Faye’s formula for the proper motion of sun spots. The velocity thus obtained, 1:42 miles per second, is so large as to suggest a physical significance, viz: that the reversing -layer, whatever and wherever it may be, has a greater angular velocity than that layer of the solar surface in which the sun spots le, a conclu- sion very interesting considering that the observations of De la Rue,}+ Stewart, and Loewy at Kew appeared to show a lagging behind of that layer of the solar atmosphere in which the faculee occur, a layer probably at no inconsiderable distance above the altitude of sun spots. Carrington,{ by a magnificent series of laborious observa- tions, extending over seven years, has determined what may. be called the proper motion of the photosphere, or more strictly, the law according to which sun spots move relatively. to one another in latitude and longitude. Have the different parts of the reversing layer a relative motion, and if so, what is the law which governs it ? It was in the hope of obtaining at least a partial answer to this question that the following observations were made. Apparatus.—The light was furnished by an equatorial heliostat with an auxiliary plane glass mirror. Leaving the heliostat, the ray next fell upon a condensing lens of 8™ diameter and 135™ focal length, thus giving upon the slit of the collimator, an image 12°5"™ in diameter. or the follow- ing apparatus to move the image across the slit, I have to thank the kindness and skill of Prof. Rowland. The condensing lens was screwed into a rectangular wooden frame which was fastened at the bottom by a single bolt to a larger iron frame. This bolt was parallel to the optical axis of the lens, and the lens could be made to rotate about it through an are of 5 or 10 degrees, thetare being limited by adjustable stops. The iron frame was, in addition, capable of lateral motion, while the lens in the wooden frame could also be adjusted ver tically. These adjustments enabled the observer to bring either limb of the * Young: this Journal, xii, 321, 1876. + Proc Roy. Soce., xiv, 37. } Carrington: Observatious on solar spots, London, 1863. LH. Crew—fotation of the Sun. 153 sun exactly on the slit, and to compensate for any slight error in placing the heliostat or in the rate of its clock. The levers by which these motions were accomplished were placed con- venient to the observer at the eye-piece. The collimator and telescope each had an achromatic objective of 64 inches diameter, made by Prof. Hastings; the former had a focal length of 7 feet and 3 inches, the latter of 7 feet and 10 inches. The angle made by their optical axes was 12°. Both were firmly attached to a long heavy cast iron frame. Jor the pur- pose of holding and rotating the grating, this iron frame car- ried upon it the tripod, circle (14 inches in diameter), and plat- form of a spectrometer. This whole system rested on a solid brick pier supported on heavy beams. These beams rested upon two partition walls of the new physical laboratory, mak- ing altogether a rigid, convenient, and accurate instrument, in which the relative position of the collimator, telescope, and grating, could be maintained perfectly constant. The eyepiece of the telescope was fitted with a micrometer screw by Grunow ; inits focal plane was fixed a very thin ver- tical glass scale, ruled in half millimeters. By this means the width of the narrow band of the spectrum during any one reading was measured, and a slight correction corresponding to this overlapping of the sun’s image on the slit was introduced into the final value of each set of observations. The grating, a plane one ruled by Prof. Rowland, was 4 inches in length and had 14486 lines to the inch. The spectrum of the fourth order on one side gave superb definition, widely dividing 6, and 6, and the lower component of E. The definition in the fifth order was, of course, not so good—though better than most of the Rowland gratings ruled with this number of lines; but in this and higher orders it was found that about as much was lost by poorer definition as was gained by increase of displace- ment. : To determine the angle which the slit of the spectroscope makes with the projected solar axis, the following method was suggested by Prof. Rowland. Between the slit and the con- densing lens was inserted a Steinheil prism mounted in a brass tube with a divided head. - This tube was so placed as to have its axis in the prolongation of the optical axis of the collimating telescope, and was made so as to rotate about this axis carrying with it the prism. The prism was placed with its refracting edge perpendicular to the ray. Before the mirror of the heliostat was suspended a fine wire plumb line. The image of this plumb line was brought to focus on the slit plate by a spectacle lens temporarily placed between the prism and the condensing lens. The angle between this image and the slit could now be measured by rotating the prism; the zero position 154 H. Crew—fotation of the Sun. of the prism being that in which two fine plumb lines, the one before, the other behind, the prism, were brought to coinci- dence. Having obtained this angle (by formula given below), we have but to add to it the parallactic angle, and the position angle of the sun, with their proper signs, to obtain the required angle, viz: the angle which the projected axis of the sun makes with the slit. This angle must finally be corrected for the in- clination ‘of the solar axis to the plane of the ecliptic ; a correc- tion never amounting to one per cent. Theory and Observations.—Let V =velocity of light, 186328 miles per sec. (Newcomb and Michelson). A=wave length of ray observed (Rowland’s Standards). v'—v""=relative linear velocity of the two limbs of the sun at the equator. x=heliocentric latitude of any point on the sun’s limb at which the slit of the spectroscope is tangent ; call this the ‘* latitude of observation.” . A=displacement of the line as measured on the micrometer. c=value of one revolution of the micrometer screw in Angstrom’s units, for the line observed. A=halt the angle subtended at the center of the sun’s image by the length of slit covered by the image. 6=inclination of plane of solar equator to plane of eliptie. g=angular semi-diameter of the sun. a=linear velocity of the earth in its orbits, expressed in miles . per second. Then, by Doppler’s principle, we have i Bp anes UT A/ i sinty eos70 Acosy cosh cos VY cos 8 +asin p where the factor ‘/eos. A is the correction for the overlapping of the sun’s image on the slit; this correction is sufficiently approximate except for very high latitudes, where a slight cor- rection depending upon y¥ must be introduced. The factor in- volving the radical is the correction for the inclination of the solar axis to the plane of the ecliptic. The addition of the last term on the right (first suggested by Prof. Oliver) reduces the velocity from the synodic to the true period* of rotation. The correction due to the rotation of the earth is so smal] as to be negligible. The following are two specimens of the individual observa- tions; the quality of the one being above, that of the other be- low, the average. * In comparing my final results with those of Young and Vogel it must be borne in mind that they have not made this reduction, and that therefore their values are for the synodic period. H. Crew—Rotation of the Sun. July 16th, 1887. Spectrum of 4th order; line, H2; Width of spectrum, 2™™; Definition, good: Half angle between plumb line and slit, ab 1202" 245730" at 1h 44m=37° 00 Readings on micrometer were begun at 15 29™ ended at 1 40™ 155 June 18th, 1887. Spectrum of 4th order, line, He Width of spectrum, 24™™ Definition, fair; Half angle between plumb line and slit, at 105 39™=29° 54’ aie JUS ete Bs) BG? Reading on micrometer were beeun at 102 59™ ended at 11> 14™ Micrometer reading. Micrometer reading. Eastern Western Wie DIACe Cai. Eastern Western Displacement limb. limb. limb. limb. rev. rev. rev. rev. 17°698 De, 0-079 17147 eleie2 Sil 0.084 (JO) “T79 69 187 267 ‘080 HN) q99 80 *208 276 "068 692 are 3 82 "212 284 072 “718 “199 81 AIG “266 070 “716 “197 81 tO} 273 082 ‘TOL “760 59 "212 *290 078 "692 “165 13 204 i293 ‘089 OS “126 53 7212 283 071 “675 “742 67 ‘211 284 ‘073 "682 “762 80 212 294 082 “661 of US) 58 218 "296 ‘078 “656 S130) 83 "214 283 ‘069 *665 Mean ‘6899 7645 17-2018 17°2785 rev. rev. . .A=0°0746 ~A=0:0767 To compute the “ latitude of observation,” y, for these two sets, we have X=I TPT where f g=angle between projected image* of plumb line and slit, at the mean time of observation. | p=position angle, taken from Secchi’s table ; Ze Soleil, 2d Ed., p. 22. [ y=parallactic angle, tabulated for the latitude of Balti more. Thus on July J6th, at 15 35™ Pp. mu. we have g=—68°'64; p=—4°40; g=+41°'94 whence y=31°'10. and on July 18th, at 115 O7™ a. M. JG=+39°'90; p=—5°:26; g=—32°°64 whence y=2°:00, * Tt must be noted that during the micrometer readings the prism was removed for the sake of definition and that, when the prism was in position, the image of the plumb line was rotated throguh twice the angle the prism was turned. 156 H. Crew—Rotation of the Sun. The following table includes all cbservations made; they are arranged in order of increasing latitudes. In the sixth column, are given the equatorial velocities, corresponding to the synodic period; these are obtained by dividing each of the observed velocities by the cosine of its respective latitude, given in col- umn five, i.e., on the assumption that the sun rotates as a solid body. In column 7 will be found the differences between each value in column 6, and the mean of all the values in column 6. TABLE I. Mean Time i ; v'-v'')—a sin Date. Observe, WOpserced |Seruneel| Onvermarion! (niles per | Differences. tion. : = sec.) July 16 11h 93m | “1474” | 13 O47 2°293 —-128 Feb. 28 129 b 6 1:05 pier Se: July 18 11 07 i, 13 2-00 27150 —-201 July 18 11] 42 dD, 13 6°35 2°297 -—-054 anya yee aa D, 13 6°64 2-070 2? SEGA Micha Shuts ean eOG 5173°8 10 6°81 2°293 = +058 Feb. 28 1 42 b 8 6:96 2°408 +:057 Duly Un oe Ll be US| cpt 13 137 2°309 ? —042 July 18 10 54 K,d 10 8-66 2:219 = 182, Mch. 8 2 50 Di 9 10°35 2321 — 024 Mch. 15 12 45 5173°8 10 10°37 2-531 +°180 Mch. 30 =| 12 16 D. 15 11°84 2°405 +°054 livable 3 H,d 13 11-86 } °2:067 2 —-284 July 22 UPI 8 CSS IAUZIG NT al 14-47 2S +020 Mch. 8 12 33 dD, 9 14:74. 2-434 +083 Feb. 28 12.25 5173°8 12 15:37 2°543 +:192 SullyiGapane tame alG Ds 13 15°83 1:950 —401 Mch. 15 1225 dD, 9) 16:06 2272 —079 Mch. 30 1 59 - De 12 16:18 2406 +°055 July 15 126 COSTA UE ets 18-36 1:914 ? —-437 Talyalo eel b Ds 13 18-44 |) 2:093°? —258 July 18 I) BS “1474” 13 19°58 2-228 = s Heb M28 ei ok 4 5173°8 7 20°75 2:756 +405 Salve 22 ei ine 100 D, 13 21°89 2-083 —-268 Mch. 8 2 41 5166°3 8 22:19 2-670 +319 Mch. 26 1°55 Ins 10 23-11 2:720 +°369 Mch. 8 fe oP NS) Dd, 7 23-28 2570 +219 Mch. 16 11 47 5173°8 10 24°51 PONT +°376- Mch. 8 11] 53 BLT? 7 24:96 2-719 +368 Mch. 11 11 53 dD, 6 26°34 2-514 +163 Mch. 30 11 18 VATA 22 27-16 2-565 4:214 Mch. 11 Hal S355 5173-8 6 27°45 2°691 +340 Mch. 8 11 38 51717 14 28°87 2-496 +145 Mch. 16 11 28 D, LO een 2 008 2:360 +009 July 12 ly dink E,d 13 30-00 2-475 +:124 Apr. 8 Dh ox 1D 10 30°64 2366 +°015 July 16 1 35 E, 13 31-10 2-424 +076 July 18 1 33 Ey 13 33°51 DU —140 Apr. 8 11 03 D. 10 34:74 2-519 +168 Apr. 8 10 38 D, 10 40°73 2-681 +°330 July 14 2052 “1474? 13 45°28 2-070 25] HH. Crew—Rotation of the Sun. 157 The observations in latitudes 6°°64, 7°°37, and all those of July 15th were made when the definition was marked “ poor,” “very poor,” “sky covered with thin clouds,” ete; I have therefore marked these doubtful, but have not rejected them entirely. The values of v’—v’’ above given are for the synodic period. The weight given to each observation is proportional to the “number of settings.” Reducing by the method of least squares, we have (since a sin y=0-086 miles per sec.) for the mean equatorial velocity, v'—v''=2°437+'024 miles per sec. which corresponds to a true period of 25°88 days. Errors.—W hen it is considered that the total displacement amounts to only ~, of the distance between the D lines, it will not be surprising if the largest error is that made in setting the cross hairs on the lines. 'T’'wo smaller errors may have been introduced by the unequal heating of the jaws of the slit; and by a slight vertical displacement of the sun’s image when shift- ing from one limb to the other. But these must have been of the second order, for immediately before making an observa- tion, the adjustment of the instrument was tested by setting on a sharp atmospheric line. Not the slightest motion could ever be detected. Since we require only the difference of the read- ings on the two limbs, and since these are taken in rapid suc- cession, and under conditions practically identical, it will be observed that all the ordinary errors of the spectrometer, ex- cept that of setting the cross-hairs, are eliminated. Errors of this kind are, however, such as would, to a great extent, counterbalance each other in a large series of observations. On the contrary, a single setting differed from the mean of the series to which it belonged, on the average, by 11 per cent, while 41 sets of observations (of eleven settings each) still differ from their mean by as much as eight per cent. This leads one to suspect the presence of irregular horizontal currents. For the regular variation of angular velocity with latitude, described below, is certainly not sufficient to account for an average error of eight per cent... Currents having velocities, very moderate indeed, compared with somealready observed by Prof. Young,* would more than account for all the irregularities of these ob- servations even if they were perfect in other respects. fesults.—W hen beginning this work, I expected to find the angular velocity decreasing as the latitude of observation in- creased, as in Carrington’s curve for the motion of sun spots, figured in Lockyer’s Chemistry of the Sun, p. 425. On,the ' * See also Schellen: Spectrum Analysis, (London, 1885), pp. 378-388. 158 H. Crew—Rotation of the Sun. contrary, it will be seen that, taking either of the observations made during the month of March, or those made in July, there appears to be a gradual enerease of daily angular motion with latitude. For the values of v’-v’’, given in column 6, Table I, are equatorial values, reduced from higher latitudes of obser- vation, on the assumption that the sun rotates as a solid body; they are therefore proportional to the angular velocities in their respective latitudes of observation. From column 7%, Table I, it is seen that the differences, between each particular value of the equatorial velocity of rotation and the mean of them all are, for the lower latitudes, mostly negative; for the higher latitudes, mostly positive. If there is any physical meaning to be attached to this, it would seem that while the sun-spot layer (or photosphere, if they be the same) is accelerated in the neighborhood of the equator, the layer, which by its absorption gives rise to the Fraunhofer lines, tends to ¢ag behind, having here a smaller angular velocity than in higher latitudes. I have drawn through the observations the straight line which most nearly represents this change of angular velocity with latitude, and find, by the method of least squares, its equation to be Y=1°158 cos x° (1+0°00835y°) where v is the linear velocity in miles per second of any point in latitude y° of the sun’s reversing layer. This gives for the - daily angular motion of any point on the reversing layer 0=794' (1+0-00335y°) while from sun-spots, Carrington* obtains for the photosphere 6=865' (1—0°191 sin £y°) As will be seen from Table I, the greatest irregularities in the value of v’—v’’ occur between the latitudes 15° and 25°. ° May this not be connected with the fact that this is the region most favored with sun-spots, the zone royale ? Two neighboring linest in the solar spectrum are often so differently affected by disturbances on the sun’s surface as to indicate that the absorbing layers to which they respectively belong are situated at widely different heights. That locus of absorption which is highest will, if we assume the sun a solid, rotate with the greatest equatorial velocity, and one might think that the values of v’-v’” for different lines should therefore arrange themselves in the same order as their corresponding metals in the sun’s atmosphere. But with a tangential slit, as used in these measurements, it will be seen that the section of the solar sphere made by a plane passing through the slit and line of sight cuts each layer (for any given latitude) in a different heliocentric longitude; so that however * Carrington: Observations on Solar Spots, p. 224. + Young: Sun, p. 100. H. Crew—Rotation of the Sun. 159 these different absorbing loci may differ in their distance from the center of the sun, the velocity of each portion of the section, resolved in the line of sight, will be the same. It will not be surprising, therefore, if in the following table no connection is seen between the order of the velocities and the order in which the elements are generally supposed to be distributed* in the solar atmosphere. TABLE II. Line. No. obs. Substance. v'-y"' Ke 26 Fe 2°289 ey4ay4” ee ( Helium + Fe 2°291 E, (double) 36 Fe+Ca 2°302 D2 50 Na 2°320 D; 106 | Na 2°420 5173-838 55 Ti (?)+ 2°590 5171-714 21 Fe 2°608 5166°3 8 Fe + 2°670 _Asa further possible test, I selected the “1474” line, of which the upper component is helium, and the lower, iron. It, if any, might be supposed to vary in width in passing from the eastern to the western limb of the sun. Accordingly one limb was brought upon the slit, and the micrometer run from one component to the other; the image was next shifted so that the other limb could be observed and the width again measured. The result, however, was entirely negative ; not the slightest difference could be found. With this instrument a displace- ment as great as ;1, of the distance between D, and D, would have been detected with certainty. Hence we conclude that, if the locus of absorption for helium is different from that for iron, and if the one be drifting with reference to the other, the rate of this motion is less than one-third of a mile per second. All attempts to measure the displacement of the helium line, D, resulted in failure, the line as seen in the fourth order not having sufficient sharpness to admit of any accuracy whatever. In the absence of other evidence, the fair inference from these observations appears, therefore, to be that there is a lag- ging of the locus of absorption in the equatorial regions, and that the amount of this drift is approximately expressed by the following equation for the daily angular motion of any point whose heliocentric latitude is y, expressed in degrees. 6=794' (1+0°00335y°). * For this distribution, see Lockyer’s Chemistry of the Sun, pp. 161-169. + Schellen’s Spectrum Analysis, p. 598. } Chemistry of Sun, p. 320. 160 H. F. Reid—Theory of the Bolometer: Art. XIV.—Theory of the Bolometer; by Harry F. Rep, Ph.D: - THE bolometer consists of a Wheatstone’s bridge in which the resistances are first adjusted so that no current passes through the galvanometer. Two arms of the bridge are made of thin platinum strips; when one of these is exposed to the radiation of a hot body it grows hotter, increases in resistance, thus destroying the balance of the bridge and producing a deflection of the galvanometer needle, which measures the in- tensity of the radiation.* Let u, v, w, be currents and! Ry AR, 1S: 7S; Gabaibe resistances in the Wheat- gram (fig. 1); and let E be the E. M. F. of the battery. By Kirchhoff’s law for the distribution of currents we find ___ ERS(k—)) mn 7iTen & where J is a function of the resistances in the various parts of the bridge. The ordinary thermoelec- tric forces at the various junctions balance each other and do not affect the currents in the bridge. The thermoelectric forces due to the Peltier effect are very small and are quite negligible; when the four arms of the bridge are equal, their effect is merely to change slightly the total KE. M. F.; we shall see later that this is unimportant. We can replace E by its equivalent in terms of the current passing through the arm #R, which contains the exposable bolometer strip. (Jor convenience we shall designate the vari- ous arms of the bridge by their resistances). This current is essentially equal to the current » in the branch R when the bridge is balanced, since w is always very small in comparison to v.t We have ; GS(1+/) +8 R+S8) v=K A p) yR(k—1) G(1 +2) +UK +3) * For a detailed account of this instrument, see Proc. Am. Acad., 1881; this Journ, III, vol. xxi, p. 187, March, 1881. + Professor Langley “On Hitherto Unrecognized Wave-lengths ;” this Journ., III, vol. xxxii, Aug., 1886, foot note p. 94. w= stone’s bridge, as in the dia-. H. F. Reid—Theory of the Bolometer. 161 If 6 is the deflection of the galvanometer needle, and D a constant depending on the form of the galvanometer, the period of the needle, ete., for small deflections s—p 2RE-D) Ve G(1+/) +7(R+8) bie A particular bolometer will have its greatest sensitiveness when for a given value of /—/, and a given ‘percentage probable error of observation, the deflection, 0, is greatest. This is ob- tained by giving proper values to D,G and vw. The proper values of D and G must be determined independently of the intensity of the current, v; for changes in these values will merely alter the sensitiveness of the galvanometer, and will change in the same ratio the total deflection 0, and the irregu- lar deflections of the needle, but will no¢ change the percentage probable error of observation. D should be made as large as possible ; 1. e. we should select the best form of galvanometer, have the needle strongly magnetised and highly astatic and its period long. The best value to give G is /(R+8)(1+/). The current v must be increased to its greatest practical intensity ; this limit, which is not at all well defined, is reached when the strip becomes sufficiently heated to set up irregular air cur- rents, which cause fluctuations in its temperature and irregular movements of the galvanometer needle, thus increasing the probable error of observation. Introducing the above value of G in the equation and writ- ing S=”k we get RD) vu ul A — an/(1+n).U1+0) We have supposed the arm /R to contain the exposable strip of the bolometer. When this is screened from radiation and the bridge properly balanced, k=/, and the resistance of this arm is7R; when exposed to radiation let its resistance kR=g/R; then D baits = ————— i) —1 UR. 1 Beem ea) (q—-1)V (1) ZR is the resistance of the bolometer strip, and the wires connecting it to the bridge, when unexposed, and is of course a fixed quantity for any particular instrument. 0 increases as Z and m decrease. In order that the balance of the bridge should not be destroyed by the continued variation of the tem- perature of the room, it is found important to have the arms of the bridge, two and two, as nearly alike as possible; a second arm therefore is made of a platinum strip like the first and placed near it in the same case, but entirely covered up. Am. Jour. Sci.— THIRD SurRizs, VoL. XXXV, No. 206.—FkEs., 1888. a 162 H. F. Reid—Theory of the Bolometer. If the branch R contains this strip, /=1. What is the best value to give n? When 2 varies from 1 to 0, 1/4/1+n varies from about 0-7 to 1; so that there is not a great advantage in making 2. less than 1; and there is a decided disadvantage. The currents in the branches R and § have the ratio v(uw—v)= S/R=n; the heat developed in Ris oR; that in S is o'R/n; if mn is much less than unity, this becomes very large, the tem- perature of the branch § is raised too high and irregular move- ments of the needle are produced. If, on the other hand, the branch JS contain the covered strip, »=1; the heat developed in Rand /R have the ratio R//-R=1//; reasoning as above we conclude that in this case the most desirable value of / is unity. To summarize : the bridge should be so arranged that =n=1; the galvanometer resistance G should equal that of the bolo- meter strip R; Band E have disappeared from the equation ; their actual values are therefore unimportant so long as v is fixed. This is applicable to the case in which we wish our instrument to have its greatest sensitiveness.. If the quantity of radiant heat to be measured is so great that this is not desired we can diminish the sensitiveness by decreasing w or D or by adding a resistance to the galvanometer branch ; it will usually be found advisable to change the first two quantities. Let us now consider the strip itself. As the intensity of the current v is limited by the excess of temperature over that of the surrounding air to which we can raise the bolometer strip without producing inconvenient movements of the galvano- meter needle, it will be convenient to replace v by its equiva- lent in terms of this excess of temperature. Let 7 be the ratio of the resistance of the exposed part of the strip to that of the whole arm in which the strip is; let ¢, be the temperature of the air and the enclosure surrounding the strip; ¢,, the tem- perature of the strip when the current v is passing through it ; m'(t,-t,) and m’(t,-t,) the loss of heat by radiation and con- vection per unit time per unit area of the blackened and me- tallic surfaces of the strip respectively (according to Newton’s law of cooling, which is sufficiently accurate for the small - changes in temperature under consideration); A’ and A”, the areas of these surfaces. We here suppose only a part of the strip to be blackened. The temperature of the strip will be constant when the amount of heat generated by the current equals the amount lost from the surface and by conduction, C, ; i, e. when viR=(A'm'+A'm")(¢,—1,) +C,. Putting the value of w derived from this equation in eq. (1), we find, writing /=n=1, . b= 2g VAn + Alm) (6,6) +O, (2) a/t oe ee Hi. F. Reid—Theory of the Bolometer. 163 q is the ratio of the resistance of the arm /4R, when the strips are exposed to radiation (their temperature then being 7,), to their resistance when screened from radiation (their tempera- ture then being ¢,). According to Matthiessen’s researches we have, for small changes in temperature, gR=R+a(t,—7#,)¢R g—1=ai(t,—t,).* We may express (¢,-¢,) in terms of the quantities of heat absorbed and given off by the strip. When the strip is ex- posed to the radiation from a hot body, the heat falling on it is increased ; we may, for convenience, consider that this latter radiation falls on the strip in parallel rays, as it approximately does. Let H be the increase of radiant heat passing unit area at right angles to the direction of propagation in unit time. 5 Fig. 2 represents the cross section of the strip; if 2 is its length,t+ Ads an element of the surface, @ the angle made by the normal to the \ surface with the direction of | propagation of the radiation from the hot body; then H. cos Odds will be the in- crease of heat falling on the element dds; if a’ and a” are the average coeflicients of absorption for the differ- ent angles of incidence act- ually occurring, of the black- ened and metallic surfaces of the strip respectively, the heat absorbed by the strip in unit time will be a ALS cos Ods+a''Hi Ss cos Gds, where the two integrals are to be taken respectively over the blackened and metallic portions of the strip, which are exposed to radiation from the hot body. If £ is the breadth of the strip, cos 0ds=dj, and the expression above becomes @’HA@’+a’ HA”; AB’ and AB” are the projec- tion as shown in fig. 2 of the blackened and‘ metallic parts respectively of the front surface of the strip. ay Sn BS * ais not the coefficient determined by Matthiessen but can be readily calcu- lated from his results. : + The bolometer strip is usually made of a number of narrow strips placed side by side and connected in series. We look upon it as consisting of a single strip bent back and forth; 4 and 6’+” are the length and breadth the exposable part would have if it were straightened out. 164 H. F. Reid—Theory of the Bolometer. The temperature of the strip will be constant when the heat developed by the current plus the heat absorbed equals that lost by radiation and convection plus that lost by conduction, C,; 1. e. when (A’m' + A”’m") (¢,—-¢,) +C,+@HAf'+a"HAp"= (A'm' + A''m") (¢,—t,) +C, ; _ (A’m'+ Alm"), ss a’ f' +a" Bp") +C,—C, Ta A’m’ + A"m" and g—l=ai(t,—t,)=ail (¢,—t,)—(4, moi at{Hi(a'f'+a"p")+C,—C, a} A’m'+A"%m" Introducing this value in eq. (2) we obtain ra Da{Ha(a' 6’ +a" B") +0,—C,} V/i(¢,—4,) (3) 44/A'm' + A"m" Hi(a'f' +a’ 8”) is the quantity of radiant heat absorbed by the strip; a and a’ will be greatest when every element of the exposed surface of the strip is at right angles to the direction of propagation of the radiant heat; i. e. when the front sur- face of the strip is flat. A’m’+A’m’’ is the heat lost from the whole surface of the strip in unit time when its tempera- ture is one degree higher than that of the surrounding air and case. Other quantities remaining the same, this will be smaller and 0 larger as A’+A”, the whole surface of the stri p is smaller. ©, and C, are smaller, the smaller the cross section of the strip. The less metal in the strip for a given exposed surface the more rapidly will it reach its temperature equilib- rium when exposed to radiation. All these considerations show that it is best to make the strip very thin. If the strip is so thin that a further decrease in its thickness would only diminish the amount of heat given off by it by a small fraction of this amount, it does not appear that any advantage would be gained by making it thinner. In the case of a strip 1™™ wide the limit is probably fully reached when the thickness* is 0:01™™. Let us now determine how much of the strip should be blackened. There are but three practical cases: I. None of the strip blackened. II. The whole surface blackened. III. The front surface only blackened. Referring to eq. (3) we see we need only consider the termt A(a' B' +a" 8") WV Amn! + Ain" * In Professor Langley’s instruments the thickness lies between 0-01™™ and 0:001™™. See his paper ‘‘On Hitherto unrecog. Wave-lengths,” cited above. + We suppose the strip to be thin enough to allow us to neglect C, and Cs. H. F. Reid—Theory of the Bolometer. 165 Write #’+8”=8; our three cases give: I. A’=~/=0; B’=8; AX =2A8; and {@é ems, a/ 2m!" ee ee Oe — ity — DAG and Oo op ONAB 2 2m! Ee Oe — 3 5 ATSAC=AB; and 0) OE Jim! +m"! Suppose a black body, with coefficients of absorption and emission, @ and m’, to be placed in a stream of radiant heat of intensity H, its rise in temperature will be given by the expression (¢,-¢,)=Ha’/2m'; if the same body should have a bright surface with coefficients a’ and m’’, its rise in tem- perature would be [¢,-¢,]|=Ha’/2m'’.. Experiments with black- ened and unblackened thermometers show that [¢,-¢,]<(¢,-4,) 5 .°. a /m" Dk BN Pe he Se Published monthly. Six dollars per year (postage prepaid). $6.40 to foreign sub- - geribers of countries in the Postal Union. Remittances should be made either by money orders, registered letters, or bank checks. GEORGE L. ENGLISH & CO, s DEALERS IN MINERALS. | A Most Complete and Choice Stock. New and Rare Species a Specialty. Finest Cabinet Specimens. Minerals for Blowpipe Analysis. - Send for our Catalogue. Mailed free to any address. One of the largest and finest private collections in America, now being retailed. Another large and exceedingly choice collection for a ae N 2 é ag sale entire. Correspondence in reference to the above solicited. GEO. L. ENGLISH & CO., Dealers in Minerals, 1512 Chestnut Street, - - Philadelphia, Pa. | THE AMERICAN JOURNAL OF SCIENCE 4 [THIRD SERIES.] ASA GRAY Our friend and associate, Asa Gray, the eminent botanist of America, the broad-minded student of nature, ended his life of unceasing and fruitful work on the 30th of January last. For thirty-five years he has been one of the editors of this Journal, and for more than fifty years one of its contribu- tors; and through all his communications there is seen the pro- found and always delighted student, the accomplished writer, the just and genial critic, and as Darwin has well said, “the lovable man.” * Asa Gray was born on the eighteenth day of November, 1810, at Sauquoit, in the township of Paris, Oneida County, New York, a place nine miles south of Utica. When a few years old, his father moved to Paris Furnace, and established there a tannery ; and the child, one account says, was put to work feeding the bark-mill and driving the horse, and another, riding the horse that ground the bark. “At six or seven he was * In the preparation of this sketch I have been much aided by the papers of Prof. Goodale, Prof. Sargent and Prof. C. R. Barnes, the last in the Botanical Gazette for January, 1886. Am. Jour. Sci.—Tuirp Serius, Vor. XXXV, No. 207.—Marcu, 1888. 11 182 Asa Gray. achampion speller inthe numerous ‘matches’ that enlivened the: District school.” At the age of eleven, nearly twelve, he was sent to the Grammar school at Clinton, where he remained for two years, and the following year, to the Fairfield Academy, both of the schools places where all the classics and mathemat- ies were taught that were required for entering the colleges of the land. But his instruction was cut short by his father’s desire that he should enter the Fairfield Medical School. This school, of high repute, was established at that place in 1812, as the College of Physicians and Surgeons of .the Western District of New York. Dr. James Hadley was the Profes- sor of Chemistry and Materia Medica, and his lectures of 1825-6, while Gray was in the Academy, and 1826-7, after he had taken up medicine, gave the young student his first in- struction in science. During the following winter at Fair- field, that of 1827-8, the article on Botany in the Edinburgh Encyclopedia attracted young Gray’s attention, and excited his interest so deeply that he at once bought a copy of “ Eaton’s Botany” and longed for spring. As spring opened, “ he sal- ' lied forth early, discovered a plant in bloom, brought it home and found its name in the Manual to be Claytonia Virginica, the species CU. Caroliniana, to which the plant really belonged not being distinguished then.” From this time, collecting plants became his chief pleasure. He finished his medical course, and, in the spring of 1831, took his degree of Doctor of Med- icine—to him the basis for a title, but not for future work. This ended his school and college days. As Gray’s scien- tific education was carried forward without the aid of a formal scientific school, so it was with his literary studies. He had not the benefit of university training, and yet became eminent for his graceful and vigorous English, the breadth of his knowledge, his classical taste, and the acuteness of his logical perceptions. Before the close of the medical course, he had opened corres- pondence about his plants with Dr. Lewis C. Beck, a promi- nent botanist of Albany, and had had a collection named for him by Dr. John Torrey of New York. Moreover, about this time, he delivered his first course of lectures on Botany, as substitute for Dr, Beck, and made use of the fees that he Asa, Gray. 183 received for the expenses of a botanical excursion through western New York to Niagara Falls. Gray also delivered a course of lectures at Hamilton College, Clinton, on mineralogy and botany, for Prof. Hadley, in the college year of 1833-4, a biographical sketch of Prof. Hadley, of Fairfield, by his son, the eminent Professor of Greek at Yale, stating that his father, who gave up his lectures at this college in 1834, “supplied his place during the last term by a favorite pupil and much valued friend, Dr. Asa Gray, who commenced under Professor Had- ley the studies which were to make him preéminent among the botanists of his time.” Prof. Hadley, the sketch says, had studied botany at New Haven, Ct., in 1818, under Dr. Eli Ives, an excellent botanist of that place, and mineralogy and geology under Prof. Silliman In the autumn of 1831, Gray became Instructor in chemis- try, mineralogy and botany at “ Bartlett’s High School” in Utica. The scientific department of the school had been under the charge of a graduate of Eaton’s “ Rensselaer School,” at Troy—the earliest school of science in America—and Professor Eaton’s practical methods of instruction in chemistry, min- eralogy and botany were there followed. Great was the de- light of the boys in botanical and mineralogical excursions with Mr. Fay Egerton, and their pleasure, too, in the lec- tures on chemistry. In 1830, the writer left the Utica High School for Yale College; anda year later, Mr. Egerton havy- ing resigned on account of his health, Gray took his place. We had then no acquaintance and knew nothing of one an- other’s interest in minerals and plants. My minerals and herbarium went with me to New Haven; and while I was there Gray was-mineralizing as well as botanizing, during his vacations, in New Jersey and western and northern New York. His first published paper is mineralogical—an ac- count of his discoveries (along with Dr. J. B. Crawe) of new mineral localities in northern New York. It is contained in the twenty-fifth volume of this Journal,* and the title gives Utica as his place of residence. He had previously made * Page 346. The article is in the second number of the volume, which was issued January lst, and is without date; the one following it is dated,Sept. 6, 1833. The paper therefore was probably written in the autumn of 1833, after a summer’s excursion. 184 | Asa Gray. excursions after plants, fossils and minerals in New Jersey, and in 1834, jomed Dr. Torrey in botanizing, besides collect- ing for him in the “ pine barrens” of New Jersey and other places. ; In the autumn of 1884, Gray accepted the position of assist- ant te Dr. Torrey in the chemical laboratory of the Medical School of New York. Botany was at first his study wader Dr. Torrey, but soon his work with Dr. Torrey ; and here commenced their long-united labors and publications. From the first he showed himself an adept in his methods of in- vestigation and in his terse and mature style of scientific de- scription. During the year 1834, while Torrey was preparing his monograph on the North American sedges, the Cyperacee, Gray had in hand an illustrated memoir on the genus Rhyn- chospora, in which he doubled the number of known North American species ; and another also on “ New, rare, and other- _wise interesting plants of northern and western New York.” Both papers were read before the Lyceum of Natural History of New York in December of that year (1834), and are pub- lished in volume iii of the Annals of the Lyceum. Dr. Tor- rey’s monograph was read on the 8th of August, 1836; and in it he says that the part on the genera Rhynchospora and Ceratoschcenus was prepared by Dr. Gray, and that his de- scriptions are so full that he gives only his list of the species with such alterations as he has thought it advisable to make, and some additional matter received since the pub- lication of his paper. During 1834, 1835, two volumes of a work on North American Graminez and Cyperacez were issued by him, each containing a hundred species, and illus- trated by dried specimens—now rare volumes, as only a small edition was published through private subscription. The first of these volumes, issued in February, 1854, only three years after his graduation at the Fairfield Medical School, is dedi- cated to his instructor and friend, Dr. James Hadley. The preface acknowledges his indebtedness to Dr. Torrey and to Dr. Henry P. Sartwell of Penn-Yan. Of the species described as new in the work, the first one, No. 20, from specimens collected by Dr. Sartwell, turned out to be Nuttal’s Calama- grostis confinis. But the next one, No. 28, Panicum axantho- Asa Gray. 185 physum, from the vicinity of Oneida Lake, stands, and is the first of the thousands of good Asa-Gray species. Thus Gray’s botanical investigations were well begun before his twenty- fifth year had passed. In February or March of 183 he gave his last instruction at the Utica High School. He expected to continue as Dr. Torrey’s as- sistant the following season; but “the prospects of the Medical School were so poor that Dr. Torrey could not afford to employ him.” He nevertheless returned to New York in the autumn, took the position of curator and librarian of the Lyceum of Natu- ral History, and continued his botanical investigations. During the summer he had begun the preparation of his “ Elements of Botany,” and in the course of 1836 the work appeared. It showed the scholar in its science and initsstyle. The subjects of vegetable structure, physiology and classification were pre- sented in a masterly manner, though within a small compass. The book, moreover, showed his customary independence of judgment and clear head in various criticisms and suggestions— later investigations sustaining them, much to his gratification. The Wilkes Exploring Expedition came near making a pro- found impression on Gray’s life. In the summer of 1836 the position of Botanist in the expedition was offered him, and accepted. But delays occurred in the time of sailing, and changes were threatened that threw uncertainties over the eruise, and for these reasons, and on account of the work on the North American Flora, of which, by invitation of Dr. Torrey, he was to be joint author, his resignation was sent in the following year. The expedition changed its commander from Commodore Patterson over a ship of the line, to Lieuten- ant Charles Wilkes with a squadron of two sloops of war (bet- ter adapted for the purpose), besides other vessels, six in all, and sailed in August, 1838. The four years abroad would have given him an opportunity for observations and discoveries that would have rejoiced him—excursions in Madeira, the Canaries, to the Organ Mountains in Brazil, a brief look about Orange Bay near Cape Horn, excursions to the Andes of Chili and about lower Peru, over Oregon and Washington territory, and parts of California, through numerous island groups of the South and North Pacific, in Australia and New Zealand, about 186 Asa Gray. Luzon in the Philippines, at Singapore, at Cape of Good Hope and St. Helena—and his open mind would have gathered in facts on the relations and geographical distribution of species that would have been to him a mine of wealth as science ad- vanced under Darwin’s lead. The place of botanist in the expedition was well occupied by the most excellent, indefati- gable and many-sided zoologist, Dr. Charles Pickering, and by Mr. Wm. D. Breckenridge, a Scotch gardener and zealous col- lector, and Mr. Wm. Rich; but with Dr. Gray, devoted to the one subject, great results would have been accomplished. North American botany, however, would no doubt have suffered. By October of 1888, a couple of months after the sailing of the Exploring Expedition, two parts of the projected “ Flora” were already out. But so many doubtful points had been brought to light, that a study of foreign herbaria had become imperative. Dr. Gray had accepted, during the summer, the chair of botany in the recently founded University of Michigan, but with the condition that he should have a year abroad for study ; and the year was given to this object. All the herbaria of Europe were carefully examined with regard to the type- specimens of American plants, and full notes taken for use in the discrimination and identification of species. The fortieth volume of this, Journal (April, 1841) opens with a highly in- teresting paper by him, giving accounts of these herbaria, their contributors, condition, and special characters, commencing with that of Linneeus and the story of its career before reaching the Linnean Society of London. His labors abroad involved an immense amount of detailed and exact observation, requiring thorough knowledge, excellent judgment, and a retentive mem- ory; and he came home well stored for the work which he and Torrey had in hand. Moreover, he made during the trip the personal acquaintance of the leading botanists of England and the Continent, and had from all a cordial reception. “In Glasgow he made the acquaintance of William Jackson Hooker, the founder of the greatest of all herbaria, the author of many works upon botany, who had already published a large part of his “ Flora Boreali-Americana, ” in which were described the plants of British North America, a work just then of special Asa Gray. 187 interest to the young American, because it first systematically displayed the discoveries of David Douglas, of Drummond, Richardson, and other English travelers in North America. At Glasgow, too, was laid the foundation for his lifelong friend- ship with the younger Hooker, then a medical student seven years his junior, but destined to become the explorer of New Zealand and Antarctic floras, the intrepid Himalaya traveler, the associate of George Bentham in the authorship of the “Genera Plantarum,” a president of the Royal Society, and, like his father, the director of the Royal Gardens at Kew. At Edinburgh he saw Greville, the famous eryptogamist ; while in London, Francis Boott, an American long resident in England, the author of the classical history of the genus “Carex,” and at _ that time Secretary of the Linnean Society, opened to him every botanical door. Here he saw Robert Brown, then the chief botanical figure in Europe, with the exception, perhaps, of De Candolle; and Menzies, who fifty years before had sailed as naturalist with Vancouver on his great voyage of discovery ; and Lambert, the author of the sumptuous history of the genus “Pinus,” in whose hospitable dining-room were stored the plants upon which Pursh had based his North American Flora. Here, too, he met Bentham and Lindley and Bauer, and all the other workers in his scientific field. “A visit to Paris brought him the acquaintance of the group of distinguished botanists then living at the French capital: P. Barker Webb, a writer upon the botany of the Canaries; the Baron Delessert, Achille Richard, whose father had written the Flora of Michaux ; Mirbel, already old, but still actively engaged in investigations upon vegetable anatomy; Spach; Decaisne, then a young wide naturaliste at the Jardin des Plantes, of which he was afterward to become the distinguished Director; Auguste St. Hilaire, the naturalist of the Duke of Luxembourg’s expe- dition to Brazil, and at that time in the full enjoyment of a great reputation earned by his works upon the Brazilian flora ; Jacques Gay; Gaudichaud, the naturalist of the voyage of T/Uranie and La Physicienne; the young Swiss botanist, Ed- mond Boissier, the Spanish traveler, and, later, one of the most important contributors to systematic botany in his classical “ Flora Orientalis ;” Adrien de Jussieu, grand-nephew of Bernard, and 188 Asa Gray. son of Laurent de Jussieu, himself a worthy and distinguished representative of a family unequalled in botanical fame and accomplishment. “ At Montpellier, Dr. Gray passed several days with the bot- anists Delile and Dunal, and then hurried on to Italy, where at Padua, in the most ancient botanical garden in Europe, he made the acquaintance of Visiani, at that time one of the principal botanists in Italy. At Vienna he saw the learned Endlicher, the author of a classical ‘Genera Plantarum ;” and at Munich, Von Martius, the renowned Brazilian traveler, the historian of the palms, and the earliest contributor to that stupendous work, the “Flora Brasiliensis,” which bears his name; and here, too, was Zucearini, the collaborator with Von Siebold in the “ Flora Japonica.” Geneva then, as at the present time, was a center of scientific activity ; and there he made the personal acquaint- ance of the De Candolles, father and son, and worked in their unrivalled herbarium and library. He saw Schlechtendal at Halle ; and at Berlin, Klotzsch, Kunth, and Ehrenberg,—famil- lar names in the annals of botanical science. Alphonse De Can- dolle and Sir Joseph Hooker alone are left of the brilliant group of distinguished naturalists who cordially welcomed the young American botanist in 1839.”* Dr. Gray also, while abroad, performed a great service for the University of Michigan, in superintending the selection of works for the nucleus of its library ; and the University showed its appreciation of his judgment, and of the benefit to the in- stitution, by honoring him, and itself, at its semi-centennial celebration the past summer, by conferring on him the degree of Doctor of Laws. Again at home, avd now well equipped for conquering diffi- culties about American species, he went at the Flora with new vigor. The first volume was completed by Torrey and Gray in 1840, and the second in February, 1843. In the interval between these dates, during the summer of 1841, Gray spent five to six weeks in a botanical excursion through the Valley of Virginia to the summits of the high mountains of North Caro- lina. A letter about the trip, addressed to Sir William J. Hooker, published in this Journal in 1842, first gives an account * From a sketch of Dr. Gray by Prof. C. 8. Sargent. Asa Gray. 189 of the excursions into these regions by his predecessors; Bartram, Michaux, and John Fraser, of the last century, and John Lyon, Michaux the younger, Pursh, Nuttall, Curtis and others, of this, mentioning their discoveries, with critical remarks on the species they observed and on their distribution; and then he describes his own journey, adding notes on the plants met with by the way and in the mountains, commencing his observations at Harper’s Ferry. His journey among the North Carolina Moun- ~ tains included the ascent of the ‘*‘ Grandfather,” 5897 feet in ele- vation, and the Roan Mountain, 6306 feet. This is one among . a number of such excursions. Another labor of this period was the revision of he “‘ Hlements of Botany,” which, without much change of general method, he made a far more comprehensive and thorough treatise, and in 1842 issued, under the title of the “ Botanical Text-book.” Since then successive editions have appeared with large ad- vances, as the science required. By the fifth edition, that of 1879, the subject had so expanded that it was divided, and the work made to include only Structural Botany, covering Mor- phology, Taxonomy and Phytography, leaving Physiological and Cryptogamic botany to other hands. The second volume, an exposition of Physiological Botany, appeared in 1885, from the pen of his colleague, Prof. G. L. Goodale. 1:10) (0038.4 7 =79bs The Mg, Aland most of the Fe were evidently combined as silicates. -The rest of the Fe was present as sulphide and oxide, and the copper as sulphide. Calculating them as such the analysis comes up to 98°36 per cent omitting the small amount of P, Co, Mn. The piece I have and others I have seen are nearly or quite black in color, and seem to have been broken from a nearly spherical mass of about 1$.or 2 feet in diameter, whose outer surface was fused. Sections under the microscope closely resemble those made from furnace slag from the reduction of iron or copper ore. It will be noticed too that the analysis corresponds quite closely to some published analyses of slag. (Compare “ Kerl’s Handbuch,” p. 856, vol. i.) * Boltzmann, Pogg. Ann., cli, p. 487. Ayrton and Perry, Jour. Tel. Engineers, vol. v, p. 481. J.D. Dana—History of the Changes in Kilauea. 213 A specimen of the copper slag from the old “ Revere Copper Works” in Massachusetts, obtained through the kindness of Dr. Wadsworth, is microscopically and chemically nearly iden- tical with the so-called meteorite. That it is not of meteoric origin thus seems to be settled, but notwithstanding the most positive stories are told about “seeing it fall,” “ getting pieces while still hot,’ ete., I have not been able to trace all such stories down. In regard to one of them I learned from the finder of a fragment which came into my hands that “in 1850, while standing upon the shore at Northport in the _evening, suddenly the region was lighted and a ball of fire passed over his head from west to east, fell into the water and exploded with a loud noise.” Failing to find any fragments he concluded that it struck too far out. In 1881, having heard that pieces of a meteor had been found there, he revisited the spot and at dead low water picked up several, one of which I have. Although the pieces he found were probably old copper slag brought by some vessel in ballast, still the fall of a meteor there cannot be questioned, and it is possible that true meteoric fragments may have been or may yet be found in that reigon. Art. X1X.—History of the Changes in the Mt. Loa Craters ; by James D. Dana. Part I. Kinavea. Continuation of the Summary and Conclusions. [Continued from xxxiii, 433; xxxiv, 81, 349; xxxv, 15 (Jan., 1888).] Il. SIZE OF THE KILAUEA CONDUIT. To appreciate the power at work in Kilauea and understand its action we should know, if possible, the diameter of the lava-conduit ; and for this we have to look to its condition both in times of eruption and in periods of relative quiet. In view of the greatness of the discharge in 1823—so under- mining, owing to its extent, as to drop abruptly to a depth of some hundreds of feet the floor of the crater, leaving only a narrow shelf along the sides—we reasonably conclude that, at that time, the conduit beneath was of as large area as the Kilauea pit itself—or nearly seven and a half miles in cireuit. We may also infer that, immediately before the discharge, wherever there was a lava-lake, the liquid top of the conduit was up to the floor of the crater, and elsewhere not very far below it. The inference is similar from the eruptions of 1832 and 1840. When the floor of the pit fell at the discharge in 1840, it was not thrown into hills and ridges, as it might have been had it dropped down its 400 feet to solid rock in conse- quence of a lateral discharge of the lavas beneath; on the AM. JouUR. Scl.—THIRD SERIES, VoL. XXXV, No. 207.—Mancu, 1888. 13 214. J. D. Dana— History of the Changes in Kilauea. contrary, it kept its flat surface, thus showing that it probably followed down a liquid mass, that of the subsiding conduit lavas. . But it is probable that the conduit had then, and has still, a larger area than that of Kilauea At the eruption of March, 1886, when the emptying of Halema’uma’u and its bordering lake, at the south end of Kilauea, was all the visible evidence of discharge, the Solfatara at the north end, two and a half miles from Halema’uma’u, showed sympathy with the movement. For the escape of vapors from its fissures suddenly ceased, as if the sowrce of the hot vapors had participated in the ebb, while a few hours before the discharge the vapors were unusually hot, so as to prevent the use of the bath-house (xxxiv, 351). Thus, even now, during a comparatively small discharge, we have evidence that the two distant extremities of the crater are underlaid by inter-communicating liquid lava. Mr. Brigham speaks of hearing, in 1880 (xxxiv, 27) when at the vapor-bath house in the Solfatara, sounds from below, “rumbling and hard noises totally unlike the soft hissing or sputtering of steam,” a fact that seems to favor the above conclusion. Further, through all known time, as now, several of the fissures in the Solfatara region have discharged, besides steam, sulphurous acid freely, and this can come only from liquid lavas. The summit of the conduit must, therefore, be even larger than all Kilauea. To this may perhaps be added the bor- dering region of fissures and abrupt subsidences; for subsi- dences or down-plunges indicate undermining, and under- mining here means the removal of liquid material from beneath. With this addition to the limits, the width is 16,000 feet and the length as much, plus a mile or more to the southwest, where the fissures of 1868 if not also of earlier date, are giving off hot vapors abundantly. But while this may be the area of the upper extremity of the conduit, the top surface is not a level plane, as the condi- tion of the region above it indicates. A small part of it at all times (with short exceptions after an eruption) has extended up to the surface in Halema’uma’n, and occasionally in other lava-lakes during times of special activity ; for each such lake, however small, must have its separate conduit reaching down to the general liquid mass and giving upward passage to the working vapors. We learn hence that whatever the number of these conduits, they may act independently, that is over- flow, and rise and fall in level, because the size is very small compared with that of the reservoir from which they rise. J. D. Dana—History of the Changes in Kilauea. 215 Ill THE ORDINARY WORK OF KILAUEA. By the ordinary work of Kilauea is here meant the work which is carried on between epochs of eruption. A large part of it is the living work of the volcano, the regular daily action, never permanently ceasing except with the decline and extinction or withdrawal of the fires. The deep-reaching conduit of lavas, which is the source of the heat and center of this living activity, owes a large part of its power to act the voleano, and make a voleaniec mountain, to the presence of something besides heat and rocks. Vapors are ever rising and escaping from -the conduit, and though lazy in the clouds above where the work is done, they carry on nearly all the ordinary action of a crater, even that of greatest brilliancy and loftiest fiery projection as well as the gentler play of the fires. But these vapors have not produced the great eruptions in Kilauea since 1822; they occasion only its quiet or lively activity in periods of regular work between eruptions. I add also, lest I be misunderstood, that the vapors are bad for fuel, as they tend to put the fires out, but good for work. There is another source of work, perhaps a perpetual source during the active life of a volcano as it is a perpetual source of heat, namely, the ascensive force of the conduit lavas. But, unlike the vapors, it is an invisible agency, slow in its irresistible movements. What areits limitations, and what its souree still remain undetermined. The other agencies concerned in the ordinary work have only occasional effects. They include heat in work outside of the conduit, and hydrostatic and other working methods of gravitational pressure.* Tabulating the agencies, they are as follows : A. The vapors. B. The ascensive force of the conduit lavas. C. Heat, displacing, disrupting, fusing. D. Hydrostatic, and other oravitational pressure. All these agencies do their work around the lava conduit, or its branches, as their central source of energy. . Unlike non-vol- * The following account of Kilauea in December, 1874, was omitted from page 94 of vol. xxxiv. It is from a brief note by Mr. J. W. Nichols, of the British Transit of Venus Expedition of 1874, published in the Proceedings of the Edinburgh Royal Society for 1875-6, pp. 113-17. A low cone around Hale- ma’uma’u about 70 feet high ; diameters of the basin $m. and +m.; within it, four lava lakes, the largest 200 yds. in length; in the largest, 7 to 8 fountains of white-hot iava playing toa height of 30 to 40 feet, one of them sometimes stop- ping, and then commencing in another part of the lake; the fountains in every case playing around the edges of the lake; lava of largest lake about 50 feet be- low the brim; one of the smaller lakes brim full of lava when in the others the lava surface was 30 or 40 feet below the brim; in one, a single fountain bursting from acavern in its side. The summit crater is stated to have been in action about a month before the visit. 216 J. D. Dana—LMistory of the Changes in Kilauea. canic igneous eruptions and nearly all other geological opera- tions, the results are pericentric. Overflows and outflows, aerial discharges and their depositions, fissure-making, subsi- dences, elevations, everywhere illustrate this fundamental prin- eiple in voleanic action. As the voleanic mountain with its crater is its emphatic expression, so is almost every little heap of lavas, or cinders, that may form within the crater or over the mountain slopes. A. The work done by vapors. Only part of the work of vapors is of the permanent kind, carried on, as above described, by the vapars rising through the lavas of the conduit. Another efficient part, but most efficient in times of eruption, is dependent on vapors generated owt- side of the conduit. In addition, there are the chemical effects of vapors. The work includes : (1) The effects of the expansive force of vapors in their escape from the liquid lavas: projectile action and its results. (2) The effects of the expansive force of vapors within the liquid lavas: vesiculation and its results. (8) The effects of vapors generated outside of the conduit: fractures, displacements, ete. (4) The chemical action of vapors; which is considered only as regards certain metamorphic effects, in connection with the account of the Summit crater. 1. THE VAPORS CONCERNED : THEIR KINDS AND SOURCES. The vapors of Kilauea have not yet been made a subject of special investigation. Still, there is no question that the chief working vapor is the vapor of water; besides which there is a little sulphur gas, and probably some atmospheric air. In- vestigations elsewhere have shown the vast predominance of water-vapor among aerial volcanic products proving that less than 1 part in 100 is vapor of any other kind. The state- ment of Mr. J. S. Emerson (xxxiii, 90) that on the west margin of Halema’uma’u, at one of his surveying stations in April of 1886, to leeward of a “smoke-jet,’ he continued his work “without regard to the smoke which the wind carried over him within a few feet of his head,’ is proof that the air held little sulphurous acid. Great volumes of vapors were constantly rising from Halema’uma’u in August, 1887. Mr. Brigham was led'to conclude from his seeing so little vapor rising from the Great Lake during his visit, that too much influence had been ascribed by others to water ;* and this view is presented also by Mr. W. L. Green, of Honolulu, * Brigham, Memoir, p. 450, and this Journal, xxxiv, 24. J.D. Dana—History of the Changes in Kilauea. 21% who refers part of the movements in the lake to escaping atmos- pheric air; the air being supposed to be carried down by the splashing and jetting lavas, there to become the source of the splashing ; and to become confined in this and other ways, and be carried deeper for other work.* But the amount of vapor escaping from a lake in times of moderate activity, when it is mostly crusted over, is very small—being only that from the vesicles (p. 194) and breaking bubbles in the actively liquid portion ; and in a state of brilliant action, the hot air above, up to a height where the temperature is diminished from that of the liquid lavas to 800° F. will dissolve and hold invisible nearly 5 times as much moisture as at 212°; up to 440°, 16 times as much: and to 446°, 27 times. The absence of vapors over a flowing lava stream is made evidence against the presence of water ; but if all is from one source, there should be none except at the source (ibid.) The amount of sulphur in the vapors, and its condition be- fore the escape from the lava, whether as sulphur vapor sim- ply or as sulphurous acid (sulphur dioxide), are questions for the future investigator. Pyrite, or some iron sulphide, being its probable source, I add that I have detected pyrite in the lava of a dike on Oahu, but not in the lavas of the crater, where we should hardly expect its presence. Chalcopyrite (copper pyrites) may also be present; for, in 1840, I found, at the southwestern sulphur banks, some blue copper sulphate. The faintly greenish tint of the flames which have been seen (xxxiv, 24, 856) may have this source. Carbonic acid has not been observed escaping from fuma- roles about any part of the Hawaiian Islands, and no frag- ments of limestone have been found among the ejectamenta of Kilauea or Mt. Loa The volcanoes stand in the deep ocean, and the conduit must come up through old lavas for thousands of feet, and hence carbonic acid is only a possible not a proba- ble product. The position of the voleanic region in mid- ocean, where continental geological work has, most probably, never gone forward, makes it questionable whether limestone is passed through by the hot lavas at any depth. The presence of hydrogen among the escaping vapors re- mains to be determined. The pale, hardly bluish flames seen about the Great Lake may come from the burning of escaping hydrogen, or of sulphur vapor, or of hydrogen sulphide. The source of the water or moisture, whence comes the chief part of the escaping vapors, is probably atmospheric. On this point the arguments appear to be as strong now as in 1840. * Vestiges of the Molten Globe, Part II, 8vo, Honolulu, 1887. + My Exped. Report, pp. 180, 201, 202, the last containing an analysis. 218 JS. D. Dana—Listory of the Changes in Kilauea. Kilauea is situated, like Hilo, in a region of almost daily mists or rains, and if approaching Hilo in the precipitation, as is probable, over 100 inches of rain fall a year. Tables give over 200 inches some years for Hilo. The whole becomes subter- ranean except what is lost by evaporation; for, owing to the cavernous and fissured rocks, there are no running streams over the eastern or southeastern slopes of the island south of the Wailuku river which comes down from the northwest to Hilo. That which falls into the crater and on its borders gives moisture to the many steaming fissures; and sometimes it makes a steaming area of the whole. But this part has very little to do with the volcanic action. A part of the subterranean waters follow the underground slopes seaward, as shown by copious springs in some ~ places near the shores ; and these also take no part ordinarily in the voleanic work. But another part must descend by gravity vertically, or nearly so, and keep on the descent far below the sea level. It has been shown on a former page (p. 16) that much the larger part of the eruptions have occurred in the months from March to June, and this appears to indicate a dependence of the action to some extent, on the abundance of precipitation. * Moisture may be gathered ae from all moist rocks alone the course of the conduit in the depths miles below the reach of superficial waters, as suggested by different writers on vol- canoes. But any dependence on the amount of precipitation would show that this is not its chief source. Another source of water is the sea. But sea-water could not ordinarily gain access to the conduit except at depths much below the sea- level, on account of the abundance of subterra- nean island waters pressing downward and outward. Farther, no one has yet reported evidence of the presence of marine salts, or chlorides, beyond mere traces, among the saline pro- ducts of Kilauea or Mount Loa after an eruption. A third source of moisture is the deep-seated region in or beneath the crust whence the lavas come. Of this we know nothing. The fact that the presence of such moisture below would make this a dangerous earth to live on has been urged against the idea of such a source. Since all ordinary action in Kilauea, and also in Mt. Loa, is of the quiet non-seismic kind, the introduction of water into the conduit must be an ordinary and a quiet process, not one of sudden intrusion through fissures. Sudden intrusions may * This view with regard to the sources of the waters is sustained by several writers. It is well presented, with explanations at length as to the water line in the voleauic mountains, in a paper on “the Ageney of Water in Volcanic Erup- tions,” by Prof. Joseph Prestwich, Proc. Roy. Soe., xli, 117. J. D. Dana—History of the Changes in Kilauea. 219 sometimes take place for eruptive effects, but of these we are not speaking. The facts from the vesiculation of some lava- flows of Mt. Loa brought out beyond (page 195) give further evidence as to the quiet molecular occlusion of the waters. Moreover, the possibility of this method of imbibition appears to be demonstrated by Daubrée’s experimental work, which proves that the process will go on through capillarity or mo- lecular movement, against the opposing pressure of vapors within.* He uses the fact to explain the origin of volcanic vapors. The water seeking entrance in the depths below, more- over, is under pressure from above, and, whatever the temper- ature, the forcing of it back against this pressure and friction is impossible ; the expansive force generated by the heat only forces it into the rising lava of the conduit, as urged by Mallet, and sustained by Prof. Prestwich. I proceed now with the consideration of 2. THE EFFECT OF THE EXPANSIVE FORCE OF VAPORS IN THEIR ESCAPE FROM THE LIQUID LAVAS: PROJECTILE ACTION. All the lava-lakes of the crater, whether one alone exists or many, and the smaller vents over fires that are concealed but not at too great depths, send forth vapors, which, in their effort to escape as bubbles through a resisting medium, that is, the lavas, do projectile work. The vapors thus produce the play of jets over lava lakes with the muffled sounds and tremor of ebullition ; and also the splashing and the throwing of spray from open fire-places in the crusted lakes. They dash up the melted fragments from a blow-hole with a rush and roar “rivalling sometimes a thousand engines,” thus introduc- ing the coarser effects of gunnery into Kilauea. They make the thin crust of the crusted lake to heave and break, press into rope-like folds the lava along the red fissures, or start a new play of fiery jets, high or low, and frequently several in alternate play; or, they make openings and push out a flood of lava; and occasionally, when rising in unwonted volume, they make lava-fountains of unusual heights over the lakes, with at times loud detonations. The projectile force required to throw up jets of lava to the ordinary height they have in times of brilliant activity, thirty feet or so (see pages 31, 32), is even less than a calculation from the height, diameter and density would make it, because the * Géologie Expérimentale, 2 vols., 8vo, Paris, 1879, p. 235. The temperature of the liquid lava is nearly that of the dissociation tempera- ture of water—1985° F. to 2370° F. according to M. H.St. Claire Deville,—and higher thau this no doubt at depths below. But that dissociation takes place within the conduit, under the pressure there existing, is not satisfactorily proved. 220 J. D. Dana—History of the Changes in Kilauea. jets before they reach their limit usually have become divided into clots, instead of remaining a continuous stream. The fact that the throw im the projectile action of a crater is usually vertical is well shown insome of the columnar driblet- cones. This is the case in that of fig. 1 below, in which the column was elongated vertically, although a result of suc- cessively descending drops. In the figure referred to, the place of ejection was at the base of the vertical part, and it is proba- ble that the force which determined the slight obliquity in the throw required for so uniform a fall on one side of it, was that of the prevailing wind. This vertical throw,—due to the fact that the top of the bubble is the weak, and, therefore the ex- ploding spot—makes the projectile action good for throwing up, but not good for a destructive bombardment of a crater’s walls. Common observations would lead us to expect that in a low state of the fires, when the large lake is for the most part thinly crusted over, the point of greatest heat and action would be toward the center; instead of this it is usually at the margin, and often in oven-like places partly under the cover of the border rocks. The only explanation that now appears is this: that along the border, the outside cold, or that of the atmos- phere, is much less felt than over the central portion. One of the secondury results, over the floor of the crater, of the projectile work is the making of the fantastic drzblet cones, formed often about blow-holes out of- the descending clots and drops, as already explained. The forms of two of these cones are shown in the following figures: the first from my p Driblet Cones. Kxpedition Geological Report (page 177) representing a foun- tain-like structure about forty feet high made of lava-drops ; the other from Mr. Brigham’s Memoir (page 423), representing “the Cathedral” as seen by him in 1864, and also earlier and later by Mr. Coan (xxxiv, 88). Occasionally the particles of the projected lava are small and ~ descend in small showers of loose smooth-faced but variously J.D. Dana—History of the Changes in Kilauea. 221 shaped bullets and granules around the vent; and this is the nearest the crater at present comes toward producing cinder- cones. Besides making driblet-cones, the projectile work raises somewhat the borders of the lakes. Further, the small over- flows, lapping in succession over the borders, often make them steep, and keep increasing their height until a heavier out-flow sweeps one side or another away. A third incidental result of the projectile action is the mak- ing of capillary glass, or Peles hair, from the glassy part of the lavas. In the jetting and splashing of the lavas, the flying clots and drops pull out the glass into hairs, just as takes place in the drawing apart of a glass rod when it is melted at middle. This is the explanation of Mr. Coan and others who have ob- served the action. Mr. Brigham says that “the drops of lava, thrown up, draw after them the glass thread, or sometimes two drops spin out a thread a yard long between them.” His new observations of 1880 (xxxiv, 22) accord with this explanation but are remarkable for the length and size of Pele’s tresses that he reports as hanging from the roofs of the fiery recesses. In my visit in 1840 to one of the smaller boiling lakes, I saw the rising and falling jets, and the work of the winds in drifting the spun glass; but my conclusion erred in attributing the spinning also to the winds. Captain Dutton’s observations led him to another explana- tion, as follows :* “The phenomenon of Pele’s hair has gener- ally been explained as the result of the action of the wind upon minute threads of lava drawn out by the spurting up of boiling lava. Nothing of the sort was seen here, and yet Pele’s hair was seen forming in great abundance... Whenever the surface of the liquid lava was exposed during the break up the air above the lake was filled with these cobwebs, but there was no spurting or apparent boiling on the exposed surface.” He then speaks of the vesicles rnade by the energetic escape of water-vapors, as solidification at the surface commences, and of their “ walls as capable of being drawn out into threads as in the case of glass.” The descending of the pieces of cooled crust “produces eddies and numberless currents in the surface of the lava;” and as’a consequence “the vesicles are drawn out on the surface of the current with exceeding tenuity, producing myriads of minute filaments” and the air agitated by the heat “lifts and wafts them away.” “It forms almost wholly at the time of a break-up ; the air is then full of it.” The microscopic structure of the capillary glass has been studied with care by C. Fr. W. Krukenberg.t In his fifty * Report, p. 108. + Micrographie der Glasbasalte vom Hawaii; petrographische Untersuchung, 38 pp. 8vo, with 4 plates; Tiibingen, 1877. : 222 J. D. Dana—History of the Changes in Kilauea. figures, a few of which are here copied, the glassy fibers are sometimes forked or branching ; sometimes welded at crossings ; often contain air-vesicles (3, 4), and microscopic crystals (1, 2, 5); often tubular (1, 2) through the drawing out of a minute —S 4 = 6 te GP 4 oO SSS Paes ee a Pele’s Hair. (Krukenberg.) air-vesicle. ‘They also show that the atr-vesicles sometimes con- tinued expanding as the glass was drawn out; and that the hair is often enlarged about enclosed crystals. The crystals are rhombic, as in the figures. The facts make it evident that the glass is far from being pure glass. 3. THE EFFECTS OF THE EXPANSIVE FORCE OF VAPORS WITHIN THE LAVAS: VESICULATION AND ITS MECHANICAL EFFECTS. a. Origin.—V esiculation, the making of bubble-like cavities in a melted rock, is a noiseless unseen effect of the vapors that are rising and expanding within the lavas. The expansion necessary to produce them is resisted by the cohesion in the lava, and by the pressure. Consequently it is a very common feature of the easily fusible volcanic rock, basalt, but not of trachyte or rhyolyte, except in pumice, the glassy scoria of these rocks; and even this glass (obsidian) commonly holds to its moisture, if it contains any, without vesiculating. Owing to superincumbent pressure, the maximum depth of vesicles is small, as has long been recognized; but how small in basalt, or any other rock, has not been ascertained by ex- periment. It probably does not occur in the Hawaiian Islands below a depth of 200 feet. Above the lower limit, vesicles may increase in number and size toward the surface, and be largest in the scum or crust, as within Kilauea; but this varia- tion upward is not always a fact. b. Kinds.—Five styles of vesiculation may be distinguished | in the Kilauea ejections, two of which characterize stony lavas, and three scorias. (1) That of the ordinary lava-stream of the floor of the pit. The vesicles are oblong ana of irregular shape, and constitute from less than 1 to 50 or 60 per cent of the mass of the rock. The form is spherical when the vesicles are very few and small. (2) That of the common stony spherically-vesiculated lava. The vesicles make 30 to 60 per cent of the mass, and are too J. D. Dana—History of the Changes in Kilauea. 228 small to be elongated much by the flow. This kind of lava occurs in streams outside of Kilauea, and in many about the slopes of Mt. Loa. The best example of it I have seen, and the basis of the fol- lowing description, is that of the 1880-’81 Mt. Loa flow, near Hilo. The small uniformly crowded vesicles constitute about 40 per cent of the mass. They characterize the lava, with scarcely any change in size and numbers, to a depth (as I found in a tunnel within the lava stream whose floor was similar) of 10 or 12 feet. Below this depth of 10 or 12 feet, the lava, as I learned from Rev. E. P. Baker of Hilo, is probably more solid, this being usually the case. ' The scoriaceous kinds are: (3) That of the glassy scoriaceous crust of the lava stream inside of Kilauea, and of the scum of its lava-lakes (xxxiv, 354). The vesicles are 65 to 75 per cent of the mass; they are elon- gated ; those at top mostly closed; those of the bottom of the crust commonly very large. The crust of the lake is sometimes so thin that stones thrown on it slump through. The glass is easily fusible and hence its rapid fusion and cooling. An analysis of this scoria-crust made, at my request, by Professor O. D. Allen, proved it to have the composition of ordinary basalt.* No analysis has been made of the stony lava of Kilauea for comparison. (4) Ordinary scoria, such as is common about cinder-cones outside of the crater, mostly stony in texture; the vesicles 65 to 95 per cent of the mass. (5) Spongy, thread-lace glass scoria, occurring as a layer 12 to 16 inches thick over the southwestern border of Kilauea (xxxiv, 359); the vesicles 98 to 99 per cent of the mass; their walls in the coarser varieties sieve-like or reticulated; in the finer, like thread-lace in texture. Similar spongy scoria is reported as occurring at the summit of Mt. Loa and about the sources of some of the Mt. Loa lava-flows; but I have seen no specimens. Since acubic inch of the finer thread-lace scoria con- tains only 1‘7 per cent in bulk of rock material, a layer of solid * Professor Allen’s analysis (this Journal, III, xviii, 134, 1879) is in column A, below. For comparison, the composition is added of (B) the doleryte (diabase) of West Rock, New Haven, Conn., of Triassic age, by Mr. G. W. Hawes (Ibid., ix, 186, 1875), and of (C) a “‘typical” basalt from Buffalo Peak, east of the west fork of the Platte, between the two Parks, by R. W. Woodward (Geol. 40th Par- allel, vol. ii, Descript. Geol., p. 126, 1877). SiO. Al,O; Fe.0, FeO MnO MgO CaO Na.O K.2O ign. P20; zaN 50°75 16°54 2°10 7°88 trace 765 11°96 2°13 0°56 0°35 a2 ORO 2 B 51°80 14:21 3°55 8:26 0°42 7°63 10°68 2°15 0°39 0°63 O14 = 99:86 C 49°04 18°11 2°71 7:70 trace 4°72 711 4:22 2°11 1:29 TiO, 2:46 = 99:47 I add that I do not cite here the analyses of the rocks and volcanic glass of Kilauea made by another for me and published in my Expedition Report, because they are erroneous and should be rejected. 224 J. D. Dana—VHistory of the Changes in Kilauea. basalt glass one inch thick would be sufficient to make a 60-inch layer of the spongy material; and probably a 75 to a 100-inch Cells of the Thread-lace Scoria. layer of the much more common, coarser variety, in which are some large vesicles occasionally half a cubic inch in size. J. D. Dana—History of the Changes in Kilauea. 225 The vesicles of the finer kind are mostly ;,th to {jth of an inch in diameter, like those of the 1880-81 Mt. Loa flow; but their walls are reduced to threads corresponding to the edges of polygonal vesicles. Figure 1 shows the general appearance of the surface in a magnified view. The forms of the skele- ton polygonal cells are, for the most part, either 12-sided or j4-sided figures, having a perimeter of ten or twelve pentag- onal faces in two alternating rows, and bases of five or six sides. The 12-sided. cells are bounded by the edges of pentagonal dodecahedrons such as come from’ the mutual pressure of spheres, except that they are distorted usually by compression, and by elongation or abbreviation. The 14-sided, which are much the most common, are similar to the 12-sided in general form, but have hexagonal bases. Fig. 2 is a side view and fig. 3 an end view of one of the latter kind, and fig. 4 shows a group of such cells, as seen over the surface of the scoria (a cut or broken surface, for it is impossible to handle a piece of the scoria without breaking off bits of the brittle threads). Fig. 6 is another of the 14-sided kind of less sym- metrical form, as is common. One of the pentagonal dodeca- hedrons is shown in fig. 7, and another in fig. 8. There is often a more complex system of network through other crossing contour-threads, but the simpler forms are referable to those represented. The inside of the base of one of the large and therefore less regular forms is shown in fig. 5, the diameter was about th of an inch. In the largest vesi- cles the walls are openly reticulated. The threads of this thread-lace scoria are not rounded, but 9. parts of the contours of the three i elliptical cells that were there in contact; and fig. 9 shows a por- tion of one. Having this form, the glassy material of the threads is thickest, and therefore of dark- est color, at the center; and they are still thicker and darker at the angles or junctions of three threads. This glassy scoria calls to mind the vesiculation of an obsidian by a high heat, converting it into pumice or scoria because of its occluded water, as illustrated by Professor Judd, and also by Mr. Iddings in experiments with the obsidian of the Yellowstone Park. The Kilauea glass must have been penetrated molecularly with water to have produced such a result. Its ejection took place after the violent projection of great stones ; and apparently not long after, as it overlies directly - the layer of stones. The conditions of origin in the cases about the summit of Mt. Loa I cannot give. But the descrip- 226 J. D. Dana— History of the Changes in Kilauea. tions seem to imply that the spongy scoria there is one of the results of high jettings or fountain-like throws of the lava dur- ing an eruption; it may be a light form of ordinary scoria. The minute delicacy and brittleness of the threads in this scoria suggests a way of making fine dust by volcanic action, which is much more reasonable than that of mutual friction of projected fragments of scoria of the ordinary kind; it thus helps in the understanding of the lofty dust clouds of Krakatau and ‘Tarawera. c. Amount of moisture required for vesiculation, its distri- bution, and its origin. —The facts derived from the crowded vesiculated lava of 1880-1881, reaching from its source down to Hilo, over 30 miles, and throughout the whole range remarka- ble for uniformity and for depth in the stream, besides giving an opportunity to study the origin of the vesiculation and the amount of moisture it requires, presents also evidence as to the origin of the moisture in the conduit and its condition. (1) As I learn from Rev. E. P. Baker, the vesicles change little toward the summit except in becoming CORTE, with thinner walls, at the source. From the mean size, J; inch in diameter, we obtain for the size of the particle of moisture required at the ordinary pressure to fill one of the vesicles, -000,000,007 of a cubic inch. What the size actually was, under the pressure and the temperature that existed at the time of vesiculation, cannot be determined. But this much we learn, that the moisture was distributed throughout the lava in a state of extreme division, actually or essentially that of molecular diffusion. (2) The space in the vesicles is 40 per cent of the mass, as determined from the specific gravity of the rock-material, 2-98, and that of the mass with the surface varnished to exclude the water, 1°88. The required water is hence 0003 per cent of the mass; or by weight :0001 per cent; showing that, the amount of water required for the vesiculation is exceedingly small, From the thread-lace scoria we find, since only 1-7 per cent | of the mass is solid glass, that the amount of moisture required to produce the vesiculation, at the ordinary pressure, would be 3°125 per cent of bulk, and 1-1 per cent by weight The amount of moisture was hence not unusual for a rock, although the vesicles occupied 98°3 per cent of the mass. (8) The source of the flow of 1880, 1881, according to Mr. Baker, was about 11,100 feet above the sea-level. This is 2575 feet below the summit of Mt. Loa, or about 1600 feet below the bottom of the summit crater. Before the outbreak, the liquid lavas were active within the crater; that is, the length of the conduit above the place of outbreak was then about 1800 feet. On account of the pressure of 1800 feet J. D. Dana—History of the Changes in Kilauea. 227 of liquid lava no vesiculation could have taken place at this depth inside of the conduit; but at the discharge, the lavas escaped from the pressure, and the vesiculation by means of the diffused moisture must have then begun. Whether the vesiculation for the whole stream took place at or near the source cannot be decided without more knowledge of the flow and its actual sources than we now have. (See further on the Summit crater, in a future part of this paper.) (4) The facts also tend to sustain the conclusion, before expressed, that the ingress of the subterranean waters, what- ever their source, took place by molecular absorption; for it produced an essentially equable molecular distribution. d. The distribution and functions of moisture after recep-— tion into the conduit.—(1.) The above conclusions from the vesi- culation have prepared the way for additional deductions as to the distribution and movements of the moisture in the con- duit. After its reception, it is exposed to a heat at least 1500° F. beyond the critical point of water (773° IF.) and retains the temperature of fusion to the surface. If the expansive force has at the ingress under the pressure any effective value, the accession of the moisture will diminish somewhat the density of the lava, that is, increase its bulk; and this increase will be greatest along the central region of the conduit because this is the region of greatest heat. If dissociation takes place, the increase is still greater, as it adds to the bulk of the moisture. It is a question, therefore, whether the pressure of the denser lateral lavas of the conduit would not have some effect toward producing an upward movement along the hotter central region. (2) The mechanism of the volcano, as regards these inside vapors, seems then to be this: (1) a molecular absorption, at depths below, of subterranean waters from regions either side ; (2) arise of the lavas, thus supplied with moisture, along the conduit. from some cause (see beyond on “the ascensive force of thie conduit lavas”) and perhaps partly in consequence of the vapors present ; (8) after reaching a level where the pres- sure is sufficiently diminished, a union of the molecules of water into gas-particles, producing by their expansive force vesiculation ; (4) a further union of particles into bubbles, when the vapors are sufficiently abundant, in order to exert the greater expansive force required to escape through the surface of the lavas, producing projectile results. e. Mechanical effects of vesiculation.—V esiculation tends in a quiet way to increase bulk, as the above mentioned facts illus- trate. It therefore will give increased height to the liquid lava in a conduit. How deep down this effect is appreciable is a point of much importance in its bearing on the movements 298 J. D. Dana—Listory of the Changes wm Kilauea. and levels of the lavas of conduits. If only to a depth of 200 feet, an average of 20 per cent. of vesicles would add only 40 feet to the height or level of the surface. But if the vapor particles at all deeper depths are, through their expansive force, undergoing gradual expansion as they work their way or are carried upward, we are still further in the dark as to the amount of effect of vapors on the bulk of the lavas in a conduit. After my observations of 1840, I was led to question, as I state in my Expedition Report, whether the effects from this means might not be sufficient to account for much of the excess of elongation of the Mt. Loa column over that of Kilauea. This is obviously not so. But how much the elongation, is an important gueatioy, and it has still to remain unanswered. 4, WORK OF VAPORS GENERATED OUTSIDE OF THE CONDUIT: FRACTURES, DISPLACEMENTS AND OTHER RESULTS. The conduit has hot rocks around it; and beneath the floor of the crater there are hot rocks about and over its upper ex- tremity. The descending waters are driven back as vapor, and usually in a harmless manner. But a sudden incursion of sub- terranean waters happening under any circumstances, might produce confined vapors of great force. The natural effects of the pressure of such contined vapors are fractures, elevations and subsidences, and, where pressure is brought to bear in a confined place on a source of liquid lavas, their injection into any open fissure at hand. These effects belong mostly to times of eruption; but in a lighter form, they may be part of the ordinary work of the erater. The lava-lakes of the bottom, even in quiet times, often have large over-flows, and also out-flows through fissures, that is both swperfluent and effluent discharges ; and it is pr obable that the cause here considered may be the occasion of part of them. Confined vapors are often generated also by the action of the heat of a lava-flow on moisture underneath. As rains fall almost every day at Kilauea, there must be more or less mois- ture underneath many parts of the cold floor; and if a few hours flow from the great lake should flood it with liquid rock, its 2000° F. which the bottom of the stream carries along and does not at once lose, would make vapor out of the moisture, having great expansive force. The large dome-shaped bulg- ings of the lava-streams and other undulations of the surface are thus accounted for on a former page (xxxiv, 356); and many of the steaming fractures of the floor as well as those of the domes may have the same origin. The next topic under the “head of . the Ordinary. work of Kilauea is “the Ascensive force of the conduit-lavas.” [To be continued. | Lo io) O. D. Walcott—The Taconic System of Emmons. 2 Art. XX.—The Taconic System of Hmmons, and the use of the name Taconic in Geologic nomenclature ; by CHas. D. Watcort, of the U.S. Geological Survey. With Plate III. THE nomenclature employed in classifying geologic forma- tions and terranes should be based upon priority of definition and upon the accuracy of the original observations; the latter to be judged by the testimony of the formations within the areas where they were first made. If the original proposer of a name bases it upon such errors of observation and interpreta- tion that subsequent observers cannot verify his work, and the name can only be used by dropping a name proposed as the result of accurate observation and definition, the latter should be retained. There is another principle that has been frequently over- looked in discussions relating to the nomenclature to be applied to geologic formations and groups of formations forming ter- ranes. It is this: In the evolution of stratigraphic and his- toric geology, stratigraphic geology preceded paleontologie stratigraphy : that is, the succession of strata for a given geolo- gic province was first determined and then the succession of organic remains in the strata. This has been so far perfected that, in most instances, the known succession of life in a geologic terrane in one province can be compared with that in some other not geographically connected with it: also, different sections of strata in the same province may be compared with one another when the continuity of the strata is broken. From this it follows: First: that the unit of geologic nomen- clature is the formation as lithologically determined, and the » combination of these units in any given section builds up the greater geologic divisions. Second: that the means of corre- lation of the formations and terranes of one province with those of another, is by the order of succession, as stratigraph- ically determined, of the contained organic remains of the respective formations and terranes. A paleontologist should rely largely upon the evidence of geologic age furnished by the fossils; but, at the same time, as a geologist, he should endeavor to obtain their stratigraphic position and order of succession in each geologic province. An example of the desirability of this is shown by the vertical distribution of the Devonian fauna in central Nevada, where several species of the Lower Devonian fauna of New York oc- cur at the Upper Devonian horizon, in the Eureka district. (Introduction to Monograph viii, U. S. Geol. Survey). AM. Jour. Sct.—Tuirp Serizs, Vou. XXXV, No. 207.—Marcu, 1888. 14 230 ©. D. Walcott—The Taconic System of Emmons. With the preceding statements in mind, I take up the ques- tion of the “Taconic System” in ceology, as one that can only be intelligently understood and decided by the application of the principles contained in them. In pursuance of a general plan the subject matter is arranged under the following heads: 1. The Taconic Area and geologic work within it. 2. Geology of the Taconic Area as known at the present time. 3. Geology of the Taconic Area, as known to Bie Emmons. 4, Comparison and discussion. 5. Nomenclature. THE TACONIC AREA AND GEOLOGIC WORK WITHIN IT. The Taconic Area.—The Taconic,area includes the Taconic range which trends north and south, nearly on the boundary line between the States of New York, Vermont, Maschchneaet and Connecticut, and the country immediately adjacent to the range, on the east and west. In this area Dr. Emmons first studied and elaborated the theory of the “ Taconic System” of rocks. For the purpose of re-investigation the counties of Wash- ington, and Rensselaer, N. Y., Bennington, Vt., and Berkshire, Mass., ‘were taken as the typical Taconic area, as they contain sections of all the formations spoken of by Dr. Emmons and, also, nearly all the localities cited by him, where the facts sus- taining the theory which he proposed could be verified. Geolog gic work within the Taconic Area.*—Quite early in the course of my study of the history of the investigation of the strata now referred to the Cambrian System in America I be- came acquainted with the voluminous literature of the Taconic controversy, and learned that two geologists only had studied the typical Taconic area with any considerable degree of thorough- ness. They were: Dr. Emmons, who founded the “ Taconic System” as the result of his observations, and Professor James D. Dana, who studied the strata referred to the “Lower Ta conic ” by Dr. Emmons. Before Dr. Emmons entered the * For an historical review of the field work and also of the opinions relating to the ‘‘Taconic System” the reader is referred to Dr. Emmons’s memoir in the Agric. N. Y., vol. i, 1847, and to the review of the Taconic System in his Amer- ican Geology, pt. 2, 1856: also to. the various publications of Prof. Jules Marcou on the Taconic System, especially ‘“‘The Taconic System and its position in Strati- graphic Geology” (Proc. Amer. Acad. Sci. and Arts, vol. xii, 1885); to Dr. T. 8. Hunt’s memoir on ‘‘The Taconic Question in Geology ” (Mineral Physiology and Physiography, pp. 516-686, 1886), also, ‘‘ The Taconic Question Restated ” (Amer. Nat. Feb., March and April, vol. xxi, 1887); Prof. Jas. D. Dana’s paper on ‘‘ The History of Taconic investigation previous to the work of Prof. Emmons” (Amer. Jour. Sci., II, vol. xxxi, pp. 399-401, 1886), and many references in the series of papers on the results of original investigations in the Taconic area, published from 1872 to 1887, by Prof. Dana. C. D. Waleott—The Taconic System of Hmmons. 231 field Professors Dewey and Amos Eaton had studied more or less of the Taconic region, and the data obtained by them were of material aid to Dr. Emmons. Among others who have examined portions of the area studied by Dr. Emmons previous to 1844, are: Dr. W. W. Mather, of the geological survey of New York, who made a reconncissance of the portion within New York State (Geol. N. Y., Rep. First Geol. Dist., 1842); Professor James Hall, who examined a section crossing from the Hudson River to the Green Mountains (Proce. Assoc. Am. Geol. and Nat., p. 68, 1845), and the Professors W. Bb. and H. D. Rogers who studied a section extending from the Massachusetts side of the Taconic area to the Hudson River (loc. cit., p. 67: also, Proe. Am. Phil. Soe., vol. ii, pp. 3 and 4, 1841). The Professors Edward and ©. H. Hitchcock described and mapped the strata referred to the “ Taconic System” in Vermont, and discussed the question of their geologic age (Geol. Vt., 1862). Subse- quently, Professor C. H. Hitchcock made a series of sections, crossing the “ Taconic System ” in Vermont (Bull. Am. Mus. Nat. Hist., vol. i, 1884). The observations made by Mr. 8. W. Ford, from 1874 to 1886, in the counties of Rensselaer and Columbia, N. Y., have furnished important data on the forma- tions examined by him that will be referred to again. Some of the results obtained. by the geologists mentioned will be spoken of under the head of ‘‘ Comparison and Discussion.” Dr. T. Sterry Hunt, Professor Jules Marcou and Professor N. H. Winchell have all written at length upon the “ Taconic System,” but I have been unable to discover that either of these gentlemen have made any field observations in the typical Taconic area * In searching for data to aid me in forming an opinion respect- ing the value ‘of the name Taconic in American geologic nom- enclature, I found that there was such a wide divergence of opinion among the geologists who had studied the “ Taconic System” in the field and those who had formed opinions upon it from partial observations in other areas, and the data given by Dr. Emmons and the Professors Hitchcock and Professor Dana, that there seemed to be no way to settle the questions at issue except by investigating the original Taconic area and , identifying and mapping all the formations within it except the areas mapped by Professor Dana and the Professors Hitch- cock, The necessity of ascertaining the age of the different * Dr. Hunt’s later opinions appear to have been influenced by his geologic obser- vations in Pennsylvania, and by certain theoretic views founded on the lithologic characters of the ‘‘ Lower Taconic”? rocks. Professor Marcou examined the ex- tension of. the “‘ Upper Taconic” ‘strata in Northern Vermont and Professor Winchell appears to have studied the publications of Messrs. Emmons, Marcou and Ford. 232 CC. D. Walcott—The Taconic System of Emmons. formations by paleontologic evidence, was also imperative, as their lithologic characters were of little comparative value out- _side of the Taconic area owing to local differences in the orig- inal sedimentation and to the subsequent alteration of the strata by metamorphic agencies. With the assent of the Director of the Geological Survey I be- gan field work during the season of 1886 and continued it until the close of the field season of 1887. A few of the results of this work were given ina paper entitled ‘Geologic Age of the Lowest Formations of Emmons’s Taconic System,” and read before the Philosophical Society of Washington, January 15th, 1887, a brief abstract of which was published (this Journal, vol. xxxill, p. 153, 1887). On the 22d of April, 1887, I read a paper before the National Academy of Sciences, at Washington, bearing the title: “The Taconic System of Emmons.” Init were given the results of my studies up to that date; and I exhibited a geologic map, and a cross-section, of the Taconic area. As I was soon to return to the field this last mentioned paper was not published.* Previous to studying the geology of the Taconie area I worked during portions of the field seasons of 1883-4 on the “Upper Taconic” strata of Northern Vermont and published a part of the results in the introduction to Bulletin Thirty%of the U. 8. Geol. Survey, 1886. GEOLOGY OF: THE TACONIC AREA AS KNOWN AT THE PRESENT TIME. The section (see map)+ crossing the Taconic area shows the general position and relation of the strata, and their geographic distribution is given on the map. In a report on the geology of Washington County, N. Y., I shall describe the geologic section in detail. For the present purpose, however, the section and map, supplemented by notes on the geologic for- mations, will I think give the data required for a cleay under- standing of the geologic terranes. Beginning on the east, the terranes will be mentioned in the order they are met with in passing westward from the pre-Cambrian crystalline gneisses of the Green Mountains to the Hudson River, and each will be given a number by which to identify it in subsequent referen- ces. One of the best localities to see the contact between the pre- Cambrian crystalline gneiss and the overlying, bedded quartzite * A short abstract of it was sent, June 8th, 1887, to Professor N. H. Winchell, reporter on the lower Paleozoic rocks to the American Committee of the Interna- tional Congress of Geologists, and was subsequently withdrawn owing to the field work of the season of 1887 having negatived and rendered obsolete several of the conclusions therein expressed. + To be inserted with the second part of this paper. C. D. Walcott—The Taconic System of Emmons. 283 is on the western crest of Clarksburg Mountain, northeast of Williamstown, Mass. It is one of Dr. Emmons’s typical local- ities, and it has also been examined by Professor C. H. Hitch- cock, who, in speaking of the relations of the quartzite to the Green Mountain gneiss, says : “3. Still more decisive is the fact that the lowest layer of the quartzite has been derived from the ruins of the. gneiss. This stratum is a conglomerate, containing many pebbles of a peculiar blue quartz, and has been observed at Clarksburg, Mass., Sunderland, East Wallingford, Ripton, and in Lauzon conglomerate, at Bristol. (The Geology of Northern New Eng- land : royal 4to, p. 2, 1870). When making observations during the summer of 1887 on Clarksburg Mountain, I found: the unconformity between the quartzite and gneiss to be well marked. The lower layers of the quartzite series contain shales and thin beds of conglomerate, and there are no passage beds between the quartzite series and the gneiss in the localities where the bedding of the gneiss and quartzite series appears to be conformable. In accordance with this, the unconformity has been represented in the section. The quartzite, including certain minor beds of schistose shale, conglomerate and limestone, I will call terrane number one. Terrane No. 1.—Professor James D. Dana, in describing the Quartzite series, in a paper on the Geology of Vermont and Berkshire, says ‘‘ Associated with the limestone belt and following mainly its eastern border there is a guurtzyte series, consisting in Vermont of quartzyte and crystalline slate or schist (hydromica slate, sometimes chlorite slate), and rising at inter- vals into mountain r idges. This quartzyte formation commences just abreast of the northern limit of the ‘ Holian limestone’ in Vermont: and it follows it southward through Massachusetts, and into Connecticut, being, throughout, its close attendant ” (Amer. Jour. Sci., vol. xill, p. 38, 1877). And on p. 204: “( 4) The age of the Quartzyte for mation, and its relation in position to the “adjoining limestone.—The quartzyte formation includes, as has been explained, strata of quartzyte and schists—some- times one predominating, and sometimes the other. The special age of the formation is in doubt, equally with that of the eastern limestones. There may be quartzytes of different. periods of the Lower Silurian: and so with the schists. The question of age can be positively answered only by the discovery of decisive fossils in the quartzyte of Vermont: and so many imperfect forms have already been brought to light (besides the unsatis- factory worm-burrows, and Fucoids or wor m-tracks) that we feel sure the future will clear away the doubts.” Protessor Dana considers that the evidence proves the ex- istence of a limestone beneath the quartzite, in some sections, 234 0. D. Walcott—The Taconic System of Emmons. but in Vermont Mr. Wing makes the limestone superjacent to the quartzite (loc. cit., p. 204). As all observers agree on the stratigraphic position of the quartzite series the paleontologic evidence of the age of the terrane, formed by that series, will be now considered. The Professors W. B., and H. D. Rogers, Edward, and C. H. Hitcheock, James Hall, Dr. W. W. Mather and Professor Jas. D. Dana have all held the opinion that the quartzite (Terr. No. 1) should be referred to the Potsdam horizon and, from its stratigraphic position, the tentative reference was in accord- ance with the facts known; but, as Professor Dana has said (ante), the question of age can only be answered by decisive fossils in the quartzites of Vermont. During the progress of the geological survey of Vermont, a few fossils were found in the quartzite. On page 356, of the Geological Report, vol. i, 1862,* it is stated: that besides Scol- ithus, a straight-chambered shell occurs in a hyaline quartz, on the west side of Lake Dunmore, and a species of Lingula in Starksboro, near Rockville; and, on page 857: ‘In the south- western part of Woodford there seem to be traces of organisms resembling bivalve shells, about the size of a three-cent piece. ” I have, through the courtesy of Professor Dana, examined two of the specimens referred to, that are now in the collection of the Peabody Museum, at New Haven, and I tind the ‘“ Modiclopsis- like shell” to be Mothozoe Vermontana, and the straight- chambered shell to be, to all appearances, a cast of Hyolithes communis, a Middle Cambrian species. Professor B. K. Emerson kindly sent to me for examina- tion the specimens from the Amherst college collection men- tioned in the Geology of Vermont, and which were collected at Salisbury, Vt. I find one to be Wothozoe Vermontana and the other species to be.a cast of Hyolithes communis, or a closely allied species. Inasmall collection of fossils, received from Professor H. M. Seely, of Middlebury college, Vermont, who found them in quartzite bowlders on the west slope of Sunset Hill, near Lake Dunmore, there occurs the Wothozoe Vermon-— tana described as “from the Potsdam sandstone,”+ and, with it, heads of a species of Olenellus undistinguishable from 0. Thompson of the Georgia formation in Franklin County, Ver- mont; and in other specimens of the quartz rock, collected at the same locality and containing WV. Vermontana and O. Thompsoni, a species of Hyolithes occurs that is undistinguish- able from HH. communis. An investigation of the reported localities of fossils, made by the writer in June and July, 1887, resulted in the discovery * Dated 1861, but issued in 1862. + Bull. Am. Mus. Nat. Hist., vol. i, p. 145, 1884. C. D. Walcott—The Taconic System of Emmons. 285 that only the Scolithus had been found zm situ. Professor H. M. Seely had traced the Rockville “ Lingula” to a bowlder, taken from a stone wall, and also the reported Lake Dunmore specimens to bowlders on Sunset Hill: no fossils being found im situ. In company with Professor Seely, I visited the Lake Dunmore locality, and found fossils in rounded quartz bowlders, but the quartz ledges gave no traces of them. The Woodford locality was too indefinitely described to be found ; but as trans- ported bowlders afforded me Nothozoe and traces of trilobitie remains, similar bowlders were probably the source of the speci- mens mentioned. In Sunderland, east of Arlington, on Roaring Branch, Scolithus occurs abundantly im s¢tu, in the quartzite; and angular blocks of quartzite were found, one mile up the ravine, that contained Hyolithes and fragments of trilobites ; but they were not traced to the beds from which they were de- rived. T’wo miles east of Bennington, however, success attended my search for fossils 72 sétw. The section begins in the woods on the west slope of the mountain on the old Weeks farm north of the old Windham turnpike. Mrooded’slope, above) pasture ..27-42-. 2645. 522 55 75 feet. 1.—Light-gray, nearly white, compact, fine-grained massive-bedded quartzite, with alternating beds of hyaline quartz. Dip 0° to 5°S.E.; SinikeseNa dopeb. (Mmaenetic) aos. 2/5 an oe Bi 2.—Light-colored, bedded quartzite, with brown spots; showing grains of sand and fossils: the latter also in the compact rock. Fossils: Nothozoe, Hyolithes and Olenellus*- -_-- 40 3.—Alternating bands of layers of light-gray and hyaline quartzite, becoming more massive GAT: OME SUNITA Ga nee eves arm ey aN pee ed S20 The dip increases from 5° to 10,° 15° and up to 25°'S. E., on the line of the section, and a lit- tle farther south, to 45° 8. E. Strike, N. 45° HK. (magnetic) 400 feet. The quartzite was traced north into the valley of Roaring Branch, and it is a continuation of the deposit on the western slope of Bald Mountain ; to the south it extends along the west side of the ridge leading to Dome Mountain, in Pownal, north- east of Williamstown, Mass. It caps the latter and crosses the narrow valley on the south tothe Clarksburg group of moun- tains, along the slopes of which it extends to a point opposite Williamstown, where it bends eastward along the south face of * I have shown elsewhere that the genus Olenellus is characteristic of the Middle Cambrian horizon, over wide areas in North America, and that it is a pre-Potsdam type. (Bull. U. S Geol Survey, No. 30, 1886.) 236 C0. D. Walcott—The Taconic System of Emmons. ? the mountain, reaching into the valley north of North Adams- Mass. On the western summit of the mountain, toward Will iamstown, the quartzite series come in unconformable contact with the pre-Cambrian gneiss; and fragments of a trilobite, apparently the genus Olenellus, were found about one hundred feet above the contact. As a result of the discovery of fossile, im situ, in the quartz- ite east of Bennington, the fossiliferous bowlders are given a value, as they were undoubtedly derived from the quartzite for- mation, and were distributed in the valley to the west during Qua- ternary time and even at the present by floods occurring in the gorges and valleys that cut thtouel the quartzite. It is now a question of search to trace the fossiliferous horizon in the quartzite from Starksboro, to Bennington, Vt. and to Dutchess County, N. Y., where Dr. Mather considered the “ Quartzite” metamorphosed Potsdam sandstone, and he so called the com- pact sandstone of Stissing Mountain, in the northeastern part of Dutchess County, N. Y. (Geol. N. Y.; First Geol. Dist?; p: 418, 1843). During the field season of 1886, I had the oppor- tunity of visiting the Stissing Mountain sandstone locality, in company with Professor W. B. Dwight, and we found Hyoli- thellus micans in the limestone layers, resting immediately on the sandstone; and the heads of Olenellus Thompsoni in the sandstone, fifty feet or more below the limestone. Hyolithellus micans is known only in the Georgia terrane of New York, Vermont and Canada. A species of Triplesia is associated with the Olenellus at Stissing Mountain, but it has little value in the correlation of strata. If we now turn to the geologic map, we find that all the localities I have mentioned are on the line of outcrop of the ae was (Hee No. 1). ratigraphy shows the quartzite series (Terr. No. 1) to ‘be the oldest of the Paleozoic sediments known on the eastern side of the Taconic area, and the contained fauna correlates it with the middle division of the Cambrian, but not as low in position as the fauna of the lower strata of the Georgia Terrane. (See Terr. No. 5. Terrane No. 2.--Dr. Emmons, when describing the sections oniGraylock yGAma Geol voli. pi 2s aprmlaiG paragraph 16), states that the “rock overlying the quartzite is again talcose slate, siliceous at its base, but purely a talcose slate as a mass and which requires no further description. It is between 400 and 500 feet thick and extends up the limestone which con- stitutes the seventh member of the Lower Taconic system.” It is this belt of shales that I have numbered 2 on the sections: and it is assumed to represent, at this point, the Potsdam sand- stone of the western side of the Champlain basin. This ter C. D. Walcott—The Taconic System of Emmons. 237 rane is so much more extensively developed farther west, in the section, that I will omit its description until passing down the western side of the synclinal formed by terrane number three. (See Section on the map.) Lerrane No. 3.—This is the limestone and marble belt that outcrops both on the eastern and western side of the Taconic range. Its distribution is shown on the map and in the sec- tion, and | think it unnecessary to restate the evidence given by Professor Dana to prove that this limestone belt is the rep- resentative of the limestones of the Trenton-Chazy-Calciferous series of the western side of the Champlain basin. His con- clusions are based on the stratigraphy, supported by paleonto- logic evidence,* discovered by Messrs. Wing, Dana and Dwight on the western side of the Taconic range, north and south of the typical area. The fossils have been referred, however, to the sparry limestone or “Upper Taconic” by those writers who favor the view of the pre-Cambrian age of the “ Lower Taconic.” Prior to August 5th, 1887, determin- able fossils had not been found in the limestone series east of the Taconic range. At that date, I found, in the eastern lime- stone, in the town of Pownal, Vt., about half a mile north of the Massachusetts line, a number of fossils that were weathered out in relief on the surface of a compact, clouded maf- ble. The collection gives Euomphalus? (fig. 1); the lower whorl and aperture of a shell like Wurchisonia bellicincta (fig. 2); two whorls of a form identical or closely allied to Murchi- sonia Millers (fig. 3). (fig. 4 isa cast of Murchisonia Milleri, from the Cincin- nati formation, for compar- ison with fig. 3): a cross- section and lower whorl of a Raphistoma-like , shell, and a large, crushed gaste- ropod shell. The fauna belongs to the Trenton terrane, and, by it, we can correlate the Eastern with the Western limestone.+ In September, 1887, I found fossils in the limestone on both * See Professor Dana’s papers in Am. Jour. Sci., 1872 to 1887. + Paper read before the American Association for the Advancement of Science, ae 15th, 1887: ‘‘ Discovery of Fossils in the Lower Taconic of Emmons.”— 238 0. D. Walcott—The Taconic System of Emmons. the eastern and western side of Mt. Anthony, on the line of strike of the Taconic range. The strata of Mt. Anthony are conformable and form a southwardly-sloping synclinal of lime- stone and marble, carrying, above, a considerable thickness of shales. On the west side the limestones dip eastward ‘and are well exposed one mile south of the Hoosie post office, N. Y. About 400 feet of limestone are shown in the section, and, near the upper part of it, shales appear which have a schistose structure. The shales are in thin beds alternating with the limestones at first, and then they increase until the interbedded limestone disappears and the typical Taconic “ talcose slates” of Emmons are the prevailing rock. In the limestones, nearly 200 feet below the shales, a stratum of limestone from two to four feet in thickness is crowded with shells of the genera Maclurea and Murchisonia. The limestone is compact and hard, so that sections only of the shells could be secured. To any one conversant with the Trenton-Chazy limestones of Washington County, N. Y., both the lithology and fossils of the Mt. Anthony limestone, at this point, would prove the geologic horizon to be that of the Trenton-Chazy. . Crossing the mountain to the eastern side, at a point three miles south of Bennington Centre, Vt., abundant fragments of crinoids occur in a dark bituminous limestone, above a band of clouded marble. In fig. 5, a few sections of a column is shown and also the calyx and portions of the arms of a crinoid, allied to Homocrinus gracilis of the Trenton limestone of New York. Above the dark shale and dipping westward with it, there isa band of arenaceous limestone upon which I noticed a fragment of an Orthoce- -| ras, an Euomphalus-like shell and sections of | what appeared to bea Rhynchonella. This lime- stone is lithologically similar to that conformably overlying a bed of marble that dips toward and passes beneath Mt. Anthony at a quarry, two miles west of Bennington Centre. I next visited the limestone at the entrance of the Hopper on the north side of Graylock peak, a typical locality of Dr. Emmons’s. The limestones and marbles are of the same litho- logie character as those of Mt. Anthony with the exception of the bituminous limestone, carrying the erinoids. Several traces of fossils were observed, but only one that could be recognized. It appears to be the inner whorl, of a gasteropod related to Euomphalus or Maclurea (fig. 6). Having verified the stratigraphy as published by Dr. Em- mons and Professor Dana, and having found Trenton-Chazy fossils in the marble belt, I crossed the Taconic range to its C. D. Walcott—The Taconic System of Emmons. 289 western base, in the town of Berlin, N. Y. The schists of the range dip to the eastward, have a greenish color, feel talcose to the touch, and appear unlike the dark shales of the Hudson Terrane. Continuing on over the range and down the western slope, I found that the schistose character of the rock was gradually disappearing and that it was becoming more shaly. The greenish color continued, but, toward the western base of the range, a mile north of the village of Berlin, the color began to change, the green and dark shales appearing in the same stratum, and even in hand specimens, and soon the dark shale of the Hudson Terrane was the prevailing rock. 84 ee! 101,011 46° approx. 46° 5? CL 321 231 NOR 87) 20c ba a 2OmORy 20° 51’ gris 321 ~ 321 G2E Ie 60ers 62 61° 357 gaviit 320A 32il 450 285 (4b 50% 45° 18! zaix 3210231 50° 10", 50° 347 50° 227 All the above angles were measured with a Fuess goniometer with two telescopes. In addition, two subordinate planes 7 and g were determined by approximate measurements as follows : eg=19", cale. 19° 267; \sn—18> -20%. calc! 18°) 467, As shown above the measured angles vary somewhat widely, but when carefully discussed it is found that no better agreement is obtained when an assumption is made that the crystals belong to a system of lower symmetry. On the con- trary the best angles lead to the tetragonal system, to which the symmetry in the development and character of the indi- vidual planes emphatically conforms. An explanation of the variation of angle is doubtless to be found in the fact stated that the crystals are all composite, and the individuals of which they have been built up are not absolutely in parallel position. A comparison of the angles given with those of K6échlin shows that he must have had crystals resembling figure 1 in hand, in fact he says that for a time he was inclined to consider his crystals as tetragonal. He was unfortunate in his material, for he adds that he was rarely able to use the telescopes of the goniometer. K<échlin’s planes referred to our fundamental form are as follows: 310=A, 110=100,.3834=e. If, however, the measurements left any doubt as to the system to which polianite should be referred, this is removed by the relation brought out by the above measurements, namely, that polianite is isomorphous with cassiterite and the allied species rutile and zircon. The relations between them are as follows. | Cc ee” ss” Cassiterite, SnO. 0°6732 46° 287 58° 19’ Polianite, MnOz 0°6647 AG aut 57° 56! Rutile, TiO» 0°6442 ABQ. ay 56° 524! Zircon, 130: 0-64.04 44° 507 56° 404’ The interesting group of oxides having the general formula RO, thus receives an important addition, a result which was not anticipated when our work was begun but which ean occasion no surprise. The hardness of both specimens of the polianite is 6 to 6:5. The specific gravity of A was found to be 4-992, the mean of three determinations, 4-971 on 0°833 gr., 4:°965 on 0°813 gr., Dana and Penfield—Crystalline form of Polianite. 247 5040 on 6:092 gr. The first two determinations were made on a chemical balance the last in a pycnometer. These results, which are somewhat higher than those of Breithaupt, were obtained with great care, the material being first boiled in water for some time to drive off the air, The erystals show perfect cleavage parallel to m, The chemical examination (Penfield) showed that the material was pure MnO,, free from all but a trace of water. The ana- lytical results are given below together with the analysis of Plattner of the original polianite : A. Ratio. B. Plattner. Ratio. WOO) Ge SalDh eee 80°81 1138 81:17 1143 (O); 2 Br ee peers 18°16 HONS 35) [18-21] 1132 Fe.0; Tak a oe lee ‘16 HT SiO, SO IS STI CCeS 36 ThaVSyo) Lae ee oe A 16 trace i13 ELS OBR a eee ee 28 trace 23:2 99°93 100°00 Loss by ignition___12°44 12°42 12°43 The ratio of MnO: O is almost exactly 1:1 and the mineral is therefore a very pure MnO,. The material which was analyzed was almost wholly scluble in HCl, leaving a very slight residue 0°16 per cent, the remaining 0°36 per cent SiO, separated from the solution by evaporation to dryness. The method of analysis was as follows: a weighed quantity of material was ignited over the blast lamp till a constant weight was obtained, the MnO, being converted into Mn,O,. After dissolving the oxide in HCl the Fe,O, and SiO, were determined and the solution tested for Ba, Ca and Mg. From the weight of the Mn,O, after deducting Fe,O, and SiO, the MnO was calculated. The excess of O over MnO was deter- mined by converting oxalic acid into CO, and collecting and weighing the same in potash-bulbs. The H,O was determined by igniting the mineral in a hard glass tube and collecting the water in a chloride of calcium tube. The chemical identity of B was proved by the fact that it gave only traces of water in a closed tube and lost 12-42 per cent by strong ignition. The ignited oxide was soluble in HCl, and gave traces of SiO, after evaporation to dryness. We purpose in a later article to present some observations upon pyrolusite and the related minerals braunite and haus- mannite, especially with reference to the relation of pyrolusite to polianite. 248 Scientific Intelligence. SCIENTIFIC INTELLIGENCE, I. CHEMISTRY AND PHySsIcs. 1. On the Stalagmometer and its use in quantitative analysis.— Two years or more ago, TRAUBE observed the markedly greater effect of iso-amyl alcohol, in lowering the height of a capillary column, over that of ethyl alcohol, even when both were diluted with water to the same extent. He based upon this observation a method for estimating the amount of fusel oil in alcoholic liq- uors, and constructed an instrument, called a capillarimeter, by which the capillary elevation could be easily measured. In a liquid containing twenty per cent of alcohol, one-tenth of a per cent of fusel oil would lower the column a millimeter. As this instrument did not prove convenient in practice, the author adopted a modified method of testing, also founded on the prinei- ple of surface tension, consisting simply in counting the number of drops contained in a given volume of the liquid. To facilitate the process, a bulb tube was used, having marks above and below the bulb, the volume between the two marks being known. Be- low, the tube was bent at right angles, united to a short capillary tube, then bent downward again, terminating in a flat disk having a small hole in the center. This instrument he calls a stalag- mometer, and by its means drops may be counted with an error of not more than 0°2 of a drop in 100 drops. To use it the alco- holic liquid to be tested is diluted to contain about 20 per cent of alcohol by volume, the stalagmometer is filled with it, the number of drops in the given volume counted and compared with the corresponding number given by pure 20 per cent alcohol. An excess in the former case of 1°6 drops in 100 corresponds to 0*1 per cent fusel oil, of 3°5 drops to 0:2 per cent, ete. Since the maximum error is 0°2 of a drop in 100, as small a quantity as 0:05 per cent of fusel oil can thus be certainly detected. In order to increase the delicacy of the method, the author concentrates the solution as follows: about 300 c.c¢. of the alcoholic liquor, pre- viously diluted to a 20 per cent strength, is placed in a stoppered separating funnel furnished with a tap, from 110 to 120 grams of pure ammonium sulphate is added and the whole is shaken, until on standing for a minute or two, it separates into two well-defined layers. The upper of these is diluted with water and two-thirds of it distilled off. The distillate is made up to 100 ¢.c., its density is determined, and after dilution to 20 per cent it is placed in the stalagmometer and the number of drops compared with that ob- tained with pure alcohol of the same strength. In a series of comparative tests, fusel oil being added to pure alcohol to the extent of 0°05, 0°10, 0°18 and 0°3 per cent respectively, the stalag- mometer method gave 0:04, 0°07, 0°18 and 0°26 per cent. In gen- eral, the influence of the compound ethers and etherial oils is too Chemistry and Physics. 249 slight to affect the result. But even this influence may be entirely eliminated by previous distillation with an alkali solution. In subsequent papers TRauBE has extended this.method to the estimation of the strength of ethyl alcohol and of acetic acid, and to the determination of the alcoholic strength of wine, beer and liqueurs. He gives carefully prepared tables of the number of drops given by mixtures of absolute alcohol and water varying by tenths from 0 to 10 per cent by weight, and in temperature by de- grees from 10° to 30°; those given by pure water at 15° being 100. At a concentration of 20 per cent, an error of 0:2 drop in 100, cor- responds to an error of only 071 per cent in the amount of alcohol. The acetic acid table is similar, but its range in temperature is only from 11° to 29° in 2° stages. The results of the method as applied to wine and beer are given and show that it may be relied on within 0°1 per cent, when used on the distillate-—er. Berl. Chem. Gres., xx, 2644, 2824, 2829, 2831, Oct., Nov., 1887. G. F. B. 2. On Apantlesis; a Separation of the Constituents of a Solution by Rise of Temperature.—Having observed that on sev- eral occasions the upper part of an alcohol thermometer column, after having slowly risen from a considerable contraction, was colorless, and that no deposit of the coloring matter (probably cochineal) had taken place, Matter was led to make further experiments in this direction. It seemed as if the colorless alcohol had by its expansion separated itself from a still perfect solution left behind. The solutions used were partly aqueous partly alcoholic, of several colloid substances, starch, tannin, caramel, albumen and gelatin. Each solution was placed in a flask of about half a liter capacity, surrounded with ice, the mouth of the flask being closed with a cork carrying a glass tube about 4"™ in diameter and 15 or 20™ long, having a glass tap near its middle point. The ice being removed the liquid was allowed to rise in temperature until the column, originally a centimeter or two below the tap, was as much above it. The tap was now closed and the liquid above it submitted to examination in comparison with an equal volume of the original solution. In all cases the liquid above the tap contained a less amount, of material in solution, in some cases very notably less; while in two or three cases there was practically none. As all the solu- tions were carefully filtered at the outset, there could have been no settling of particles. The conditions influencing the result seem to be: first the proportion of the colloid solid in solution ; and second, the time occupied in the rise of temperature. The author has given the name apantlesis to this phenomenon, signify- ing a draining away of some of the molecules of the solvent from those of the colloid while the solution was undergoing expansion. —Chem. News, lvi, 146, Oct., 1887. G. F. B. 3. On the Properties of Fluorine.-—Motssan has published in full his investigation upon the isolation of fluorine, made in Debray’s laboratory. As we have already noticed his methods* * See this Journal for March, 1887, p. 236. 250 Scientific Intelligence. we give here his conclusions on the properties of fluorine. It is a colorless gas, having an odor recalling that of hypochlorous acid. It combines directly with hydrogen even in the dark and without the aid of heat; being the only instance where two gases unite directly without the aid of external energy. Sulphur, selenium and tellurium are inflamed on contact with it. Phosphorus takes fire in it, and yields a mixture of oxyfluoride and of fluorides of phosphorus. Iodine burns in it with a pale flame; arsenic and antimony unite with it with incandescence. Crystallized silicon, cold, burns brilliantly in it, yielding the gaseous fluoride. Ada- mantine boron also burns in it, but “with more difficulty. Potassium and sodium become incandescent when cold, iron and manganese when slightly heated. Mercury absorbs it completely, but gold and platinum are not attacked by it at ordinary tempe- ratures. Melted potassium chloride and iodide are at once attacked by it, the chlorine and iodine being set free, the latter in the form of crystals. Water is decomposed by it in the cold, forming hydrogen fluoride and setting free ozonized oxygen. Carbon disulphide is at once inflamed by fluorine; and when this gas is received in carbon tetrachloride, it produces a continual evolution of chlorine. Organic bodies containing hydrogen are violently attacked by fluorine. A fragment of cork is carbonized at once and ignited if placed in front of the evolution tube. Alcohol, ether, benzene, turpentine, petroleum take fire on contact with this gas. Ina word, fluorine appears justly to occupy the place hitherto assigned to ‘it at the head of the group of halogens, as a substance whose activity surpasses that of any other element.—Ann. Chim. Phys., V1, xii, 472-538, Dec., 1887. G. ob) B: 4. On Oxygen Carriers —LotHar MEYER has made a series of experiments to test the alleged function of certain substances as oxygen carriers. Oxygen and sulphur dioxide gases were passed for four hours, as a rule, through solutions of the salts to be tested, of known concentration, heated in flasks placed on the water bath. After expelling the excess of sulphur dioxide by carbon dioxide gas, the sulphuric acid which had been formed in the solution by oxidation was determined by analysis. The results confirmed the alleged fact. The most active salt was manganous sulphate, MnSO, . (H,O),, 2:404 grams of which dis- solved in 200 c.c. of water, produced five times as much sulphuric acid as the salt itself contained ; i. e., (H,SO)), for Mns@r Manganous chloride was also active and produced 4°3 molecules Ee SO, in the same time. The salts of copper, iron, cobalt, nickel, zine, cadmium and magnesium were also active but in a less degree ; while thallium and potassium salts gave no result. The author attributes this action to alternate oxidation and reduction, since those metals are the most active which pass most readily trom one stage of oxidation to another.— Ber. Berl. Chem. Ges., Xx, 3058, Nov., 1887. G. HaeBs 5. On the Atomic Weight of Zinc.—RryNoLps and Ramsay by measuring directly the hydrogen set free by the solution of a Chemistry and Physics. 251 known weight of zinc in acid have obtained the value 65°50 for the atomic weight of this metal. This method has the advantage of being independent of any other atomic weights.—/. Chem. Soc., li, 854, Dec., 1887.. G. F. B. 6. A Texi-book of Inorganic Chemistry.—By Prof. Vicror von Ricuter. Authorized translation by Prof. Engar F. Samira. Third American from the fifth German edition. 12mo, pp. xvi, 428. Philadelphia, 1887. (P. Blakiston, Son & Co.)—This book has been for some time in the hands of American readers, and the demand for.a third edition is evidence that it has been well re- ceived. In the thirty pages of introduction, the author sketches the province of chemistry, its symbols and formulas, the principles of energy, and the conservation of energy, the energy-relations of chemical changes and crystallography. The elements are then taken up, beginning with hydrogen, and the philosophy of chem- istry is gradually worked in as it is required. For instance, after the hydrogen compounds of the halogens, the law of definite pro- portions, the atomic theory, and the volume relations of the ele- ments are discussed. A hundred pages later come atomic and molecular values, valence and chemical structure; and at the close of the non-metallic groups, the periodic system is considered. An excellent feature of the book is the considerable space given to the energy relations of chemical changes, particularly to heat re- lations. The distinction drawn by Berthelot between epothermic and endothermic reactions is emphasized and the great importance of such reactions as H ++ CI= HCl + 22000 eal. and H+I=HI—7000 cal. is maintained firmly. Weare glad to note an extension of this thermal discussion, as well as of other physical relations, in- timately associated with chemistry, in this third edition. The section on Mendelejeff’s periodic system of the elements is care- fully written and gives an excellent account of this remarkable classification. In an appendix is given the heat of formation of the most important metallic compounds according to J. Thomsen. Dr. Smith has performed well the part of a translator, although a want of perfect smoothness in flow sometimes betrays the difi- culties he has had to contend with. The printing and mechanical work are good, but the woodcuts seem hardly up to the standard of the rest of the book. Go eB: 7. A Manual of Analytical Chemistry ; by Joux MurTer. Third edition. 200 pp. Philadelphia, 1887. (P. Blakiston, Son & Co.).—Muter’s Analytical Chemistry appears in the third edi- tion in compact form but enlarged in scope. Of the host of works of its kind, dealing simply with the outlines of the subject, it is one of the fullest and best. 8. A new instrument for measuring heat.—Prof. WEBER at a meeting of the Helvetii Society of Sciences described the follow- ing very sensitive micro-radiometer. One arm of a Wheatstone bridge is formed by a thin tube, which is filled in its middle part with mercury, and at its ends, for about 5"™, with a solution of zinc sulphate. ‘To each end of the tube is fitted a metallic case, one side of which consists of a plate of rock salt. This case is 252 Scientific Intelligence. filled with air, which dilates under the influence of radiation, forces back the zinc sulphate solution in the tube, and thus greatly increases the electrical resistance on that side. The apparatus is made symmetrical to eliminate variations of pressure and tem- perature. This radiometer will indicate one hundred millionth of a degree. The moon’s radiation gives a galvanometer deflection of five divisions.— ature, p. 157, Dec. 15, 1887. ie a 9. Velocity of Sound.—At a meeting of the Physical Society, London, Noy. 12, Prof. A. W. Rucker exhibited an apparatus for determining the velocity of sound on the principle employed by Fizeau for measuring the velocity of light. ‘“ A vibrating reed is used as the source of sound and a sensitive flame as the receiver. A long U-shaped tube has its two ends placed near and parallel to the plane of a perforated disc, which is capable of rotating about an axis perpendicular to its own plane, The reed and sensitive flame occupy similar positions on the opposite side of the disc. On rotating the disc the sensitive flame flares or is quiescent according as the time taken to travel the length of the 1 ’ : dl : ; tube is an éven or an odd multiple of oe where T is the time of one revolution and z the number of holes in the disc.”—Lature, Ps 119s Decrees 7: dg 10. On the transmission of power by alternating. electrical cur- rents.—Mr. T. H. BLAKESLEY, in a communication to the Physical Society, London, Nov. 12, discussed the relative efficiency of the transmission of power by direct and by alternating dynamos, and concludes that the ratio of power to weight is much greater for a direct than an alternating current motor. The author considers this a great drawback to the employment of the latter. He also showed that by placing a condenser between the terminals of the recipient machine a greater current could be passed through the receiver than that in the generator and line.—Wature, p. 119, Dec. 1, 1887. Yo WE, 11. Measurement of Hlectromotive [Aes eh Witiiam THom- son has employed his new deciampere balance to the determina- tion of the electromotive force of a Clark cell. The result ob- tained was 1:436 volts at 15° C. The result obtained by Lord Rayleigh was 1:435 at 15° C.— Phil. May., p. 514, Dec., 1887. Sib) th 12. Influence of Magnetism on the Thermo-electric behavior of Bismuth.—Dr. Giovanni Pietro Grimapi shows that the ther- mo-electric behavior of bismuth in relation to copper is weakened by Tang neusHy The diminution of the electromotive force was about ~, —, and seemed to be of the same order of magnitude as the variations in electrical resistance investigated by Righi.— Rendiconti della R. Accademia dei Lincei, Feb., 1887. Jon 13. Coincidences between lines of different Spectra.—The diffi- culty of deciding upon the existence of a metal, like cerium, in the sun, is very great, since, on account of the number of lines in the spectr um of the metal, the probability of many of its lines coin- ciding in position with lines in the solar spectrum is very great. Chemistry and Physics. 253 This coincidence may be only accidental. Schuster has employed a criterion which depends upon a supposed harmonic relation be- tween the lines of a spectrum. Mr. Love employs a method of discrimination based upon the law of error. The differences between the wave-length of the lines compared are arranged in groups, each group containing those observations, the errors of which lie within certain narrow limits. The number of observa- tions in each group is then plotted as an ordinate of a curve, the average error of the group being the abscissa. This curve is then 2,2 compared with the law of error y = ae—°”. To show the appli- cability of the method, various curves are given, notably those ‘due to observations on cerium and the spectrum of water.— Phil. Mag., Jan. 1888, pp. 1-6. That 14. Influence “of thickness and luninosity of light-producing layers, upon the character of spectra.—Certain authors, notably Wiillner in his work on Experimental Physics, maintain that line and banded spectra can be made interchangeable by modifying the pressure of the gases or increasing or diminishing the extent of the layer which is made luminous by electrical discharges. Expurt, by a series of experiments, is brought to the conclusion that the experiments adduced by Wiillner and other writers, merely show that banded spectra can be reduced to line spectra by diminishing the illumination. No increase or diminution of density or thickness of luminous layers can account for the change of one class of spectra with another. This change must be rather attributed to a change inthe molecular grouping.—Ann. der Physik und Chemie, No. 1, 1888. ey. 15. On the measurement of force of gravitation.—The deter- mination of the force of gravitation by means of a pendulum, it is well-known, requires great skill and the employment of many corrections. In a note presented to the Academy of Science, M. DerFrorGcEs shows that we can eliminate the effects of the sup- port and that due to the curvature of the knife-edges by making use of two pendulums which oscillate within the same limits of aniplitude upon the same support and the same knife edges. These pendulums have the same weight, but are of different lengths. Their centers of gravity are similarly placed in regard to the sides of the knife-edges.— Comptes Rendus, Jan. 9, 1888, p- 126. J. T. 16. Influence of temperature on Magnetization.—In studying this subject, M. Ledeboer made use of the novel plan of placing the bars of iron or steel in platinum spirals which were heated to suit- able temperatures by means of an electrical current. The soft iron examined by M. Ledeboer, lost its magnetism entirely at 770° C. and had barely any at 750°C. Ina recent study upon the spe- cific heat of iron at high temperatures, M, Pionchon has shown that iron undergoes a change of state between 660° and 720°. Tron loses its magnetic properties also between 680° and 770°. M. Ledeboer calls attention to this remarkable fact.— Comptes Rendus, Jan. 9, 1888, p. 129. ayaa 254 Scientific Intelligence. II. GroLtocy AnD MINERALOGY. 1. Note respecting the term Agnotozoic.—In the closing por- tion of the article in the November number of this Journal entitled “Is there a Huronian Group?” Prof. R. D. Irving has advocated the adoption of the term “Agnotozoic” as a compre- hensive designation for the fragmental rocks which lie between the base of the Cambrian formations and the summit of the Ar- chan crystallines, and has credited me with the authorship of the term and the early advocacy of the desirableness of a distinet name for these formations. Concerning this I wish to file a dis- claimer; not that I do not fully concur with Professor Irving in this advocacy, for I do most cordially, nor because I suppose it to be a matter of consequence to Professor Irving, since I know that he holds all questions of priority or proprietorship in nomencla- ture in little esteem, if not in hight contempt. I wish to file the disclaimer not because of this special case but out of respect for a general principle in nomenclature, which I hope to see adopted to the displacement of a purely technical and indiscriminative ap- plication of the law of priority. I hold that nomenclature of the class in question should rest, not with some individual, who, standing by and looking upon the work of others, may see, per- chance before they do, whereunto their labors are growing; nor with some one, who, on the basis of superficial observation and hasty conjecture, throws out first to the world a tentative nomencla- ture, leaving it to the future and to the labors of others to justify or reject; but on the contrary, I hold it should rest with the patient and thoroughgoing investigator, who by careful and com- prehensive study develops an adequate basis for nomenclature, properly sanctioned by a broad and trustworthy array of facts. T have been in some senses a student of the formations to be em- braced under the proposed term, but in no such sense as to give me the right of nomenclature under this principle. . If, therefore, this term shall be adopted, as I sincerely trust it may, I earnestly desire that it shall stand to the credit of some one who has had a larger part in the actual development of the facts upon which its adoption must rest, among whom I know of no one who has con- tributed more than Professor Irving. If it were needful I could take refuge behind the fact that al- though I have used the term in correspondence, conversation, discussion and other informal ways for the past two years, more or less, I have nowhere formally proposed it in a scientific publi- cation; but it is the principle of just nomenclature, and not a spe- cific result in this case that gives purpose to this note. On this principle, as well as technically also, the name Kewee- nawian or Keweenawan should be credited to Major T. B. Brooks, or to Messrs. Brooks and Pumpelly jointly, since it was through their labors that there was first presented a sufficient body of specific facts, correctly interpreted, to justify the adoption of the term by those who accept the distinctness of that formation. The Geology and Mu ineralogy. 255 term Keweenian was not only proposed subsequently, but rested upon no extensive, careful and specific field investigation on the part of the author, which, on the principle above indicated, is the necessary sanction of acceptable nomenclature. T. ©. CHAMBERLIN. University of Wisconsin, Nov. 15, 1887. 2. Contributions to the Paleontology of Brazil, comprising descriptions of Cretaceous Invertebrate fossils, mainly from the Provinces of Sergipe, Pernambuco, Para and Bahia; by CHARLES A. Wurrr. From vol. vii of Arch. do Mus. Nacional do Rio de Janeiro. 274 pp. 4to, with 28 plates.—The Cretaceous fossils described by Dr. White were collected by the Geological Survey of Brazil while it was under the charge ot Prof. C. F. Hartt, and were sent to Dr. White for description by Mr. Orville A. Derby. The rocks occupy a coast region from the mouth of the Amazon southward for eighteen degrees of latitude. The fossils include many Cretaceous types, but it is remarkable, says Dr. White, that the conchifers, and especially the gasteropods, have little in common with those of North America. The fauna as a whole seems to be more nearly related to the Cretaceous of southern India than to any other that has been investigated—a fact appa- rently indicating that part of the peculiarities may be due to the equatorial temperature. The fauna is spoken of as having also a Tertiary feature in the presence of species of Fusus, Murex, Phorus, etc. The most of the species are new. They are beautifully figured on the 28 lithographic plates. The Cephalopods are re- ferred to thirteen species and among them there is one Helicoceras. The Ammonites include Ammonites Hopkinsi of Forbes which agrees well with Stoliczka’s figures of a specimen from India, and A, planulatus Sowerby, which also occurs in India, or a species very near it. Plates 27 and 28 are devoted to the Echinoderms, of which there are 15 species. 3. Arkansas Geological Survey.—The Geological Survey of Arkansas, under the charge of Dr. Branner, is going forward with vigor, through the aid chiefly of volunteer assistants. A report on Clarke County by Mr. R. T. Hill, with a geological map, will be finished this season, and another, on Washington County, by Dr. F. W. Symonds. Work is going forward also on the coal fields by Arthur Winslow. 4. Fossils of Littleton, New Hampshire.—The Littleton fossils were referred to the Niagara group by Prof. C. H. Hitchcock, in 1884, in a paper on Geological Sections crossing New Hamp- shire and Vermont, in the Bulletin of the American Museum of Natural History of New York. 5. Paleolithic Man in Northwest Middlesex: The evidence of his existence and the physical conditions under which he lived in Ealing and its neighbourhood, illustrated by the condition and culture presented by certain existing savages; by Joun ALLEN Brown, F.G.S. 228 pp., 8vo, with frontispiece and 8 plates. London, 1887. [Macmillan & Co.]—This interesting volume is Ea} 256 Seventific Intelligence. illustrated by figures of flint implements of various forms from the vicinity of Ealing. To these are added representations of similar implements from other beds of like age, and also from those now in use among existing men, as the Esquimaux, Aus- tralians, Fuegians and others ; and the frontispiece represents, in an ideal picture, the method of chipping the flint into arrow-heads and other forms. 6. On the Organization of the Fossil Plants of the Coal Measures. Part. XIII; by W. OC. Witttamson, LL.D., F.BS. Philosophical Transactions of the Royal Society of London, vol. elxxvill, 1887.—Nearly six years have elapsed since the appear- ance in 1882 of the twelfth of this remarkable series of memoirs which, prior to that date had been issued at the rate of one every year since their commencement in 1871. The casual observer might infer from this that the powers of the distinguished author were failing, but when we learn what other work he has done during this interval we cannot wonder that the special investiga- tions ‘which are recorded in these memoirs have been somewhat interrupted. k ‘ One would suppose that the preparation of his splendid Mono- graph on the Morphology and Histology of Stigmaria ficoides, published by the Paleontographical Society in 1887, might have occupied the whole of this time, not to speak of his work for the British Association, as president of the Geological Section and on committees for the investigation of the Tertiary flora of the north of Ireland and of that of the Halifax coal measures, which, with his other collateral work aggregate a score or more of im- portant contributions from his pen to the science of fossil plants during the past five years. The present memoir deals with some new phases of his two genera, Heterangium and Kaloxylon, which he established in Part | IV of this series in 1873. The most important fact now brought out is that these plants, while possessing most of the points of structure essential to ferns, have, nevertheless, at the proper period of their growth, a distinct exogenous zone with a cam- bium layer separating the xylem from the phloem. Relative to the systematic position of these remarkable plants he is only cer- tain that they have no representatives among living plants. He suggests the possibility of their being the generalized ancestors of both ferns and cycads, and cites Stangeria with its fern-like dichotomous nervation linking these two families of plants by their foliage in a manner similar to that in which these extinct forms link them by their internal structure. L. F. W. 7. Catalogue of the Fossil Mammalia in the British Museum; by Ricnarp LypreKKer, F.G.S., part V, London, 1887.—This Part finishes the Catalogue. It includes the group Tillodontia, and the Orders Sirenia, Cetacea, Edentata, Marsupialia and Mono- tremata, together with miscellaneous notices in a supplement. The critical notes in this Catalogue give it very great value. 8. The Geological Evidences of Evolution ; by ANGELO HErL- PRIN, Prof. Invert. Pal. and curator Acad. Nat. Sci. Philad., Geology and Mineralogy. 257 100 pp., 12mo., Philadelphia, 1888.—Prof. Heilprin has here presented a briet review of the more prominent facts in paleon- tology supporting the theory ‘of evolution. It is a carefully prepared statement made with little technicality, and illustrated by good figures. 9. Kilauea.—In the paper by Mr. J. S. Emerson, in volume XXXIll, page 90, the words “ Little Beggar,” in line 27 from the top should be “ New Lake.” 10. Allgemeine und chemische Geologie von Justus Roru. 2nd volume, third part closing the volume. Crystalline Schists and Sedimentary Rocks.—The author opens his chapter on the Crystalline Schists with the remark that in his opinion, the schists are Plutonic, or the material of the earth’s first-cooled crust. He has thus got back to old an error, through the help of the new facts put forward by Dr. Lehmann, just at a time when opposing facts are fast multiplying. The value of the work, however, is not much affected by the theoretical assumption, ex- cept that he cites statements that coincide with the view, and omits the facts that disagree with it. The rocks are described with fullness, many chemical analyses are given, and long lists of localities are added. Quartzite is placed rightly both under “crystalline schists” and “ Neptumian rocks;” but among his North American localities those of the Taconic region of west- ern New England are omitted; evidently because the associated mica schists of Western Massachusetts, alternating in some places with the quartzite, would throw them with the ‘ Plu- tonic,” and yet a Lower Paleozoic age is claimed for them, which puts the author in suspense. 11. Mineral Resources of the United States.—Calendar year 1886. Davin T. Day, Chief of Division of Mining Statistics and Technology. 813 pp. 8vo. Washington, 1887, (U. 8. Geological Survey, J. W. Powell in charge). This fourth volume of the se- ries of reports on the Mineral resources of this country, appears with commendable promptness, reflecting credit in this respect as in others upon the editor, Mr. David T. Day. Its scope is similar to that of its predecessor, and like them it contains an immense amount of valuable practical and scientific information not to be obtained elsewhere. A large part of the space is given to de- tailed discussions in regard to the important metals, fuels, build- ing stones, etc., but there is also considerable fresh information as to the rarer substances of less economic value. 12. Native Platinum from Canada.—Mr. G. C. Horrmann, of the Canada Geological Survey, has contributed a series of analy- ses of native platinum from Granite Creek, a branch of the Tula- meen River in British Columbia. The specimen in hand con- sisted of 98 per cent platinum with a little gold and ‘pyrite; the specific gravity was found to be 16°656 after removing the foreign matter. It was separated into a magnetic portion (A), 37°88 per cent, with G.=16°095, and a non-magnetic portion (B) with G.= 17°017. The mean analyses gave: 258 Scientific Intelligence. Pt Pda Ra Ir Cu Fe lIridosmine Chromite A. Magnetic, 78°43 0°09 1:70 1:04 3:89 9:78 Braud L:27= 99°97 B. Non-magnetic, 68:19 0°26 3:10 1:21 3:09 87 14:62 1:95=1060'29 The magnetic portion was distinctly magneti-polar, but it was not found to contain appreciably. more iron than the others, although that might have been anticipated.— Zrans. Roy. Soc. Canada, 1887. ; 13. The Shepard Collection of Minerals.—The very large and valuable collection of minerals and meteorites belonging to the late Prof. Charles U. Shepard, has been generously given, by his son, Dr. Charles U. Shepard, to Amherst College. The estimated value of the collection is ten thousand dollars. ; 14. Natural Gas.—Supplement of December 30, of the Ameri- can Manufacturer and Iron World of Pittsburg, contains valua- ble papers, both geological and economical, on Natural Gas, by the best American writers on the subject, C. A. Ashburner and John F. Carll, of the Pennsylvania Geological Survey, with a map of western Pennsylvania, also of Kansas, and by Dr. A. J. Phinney, of Indiana, with a map of the Indiana gas field, and other notes on the subject. Ill. Botany. 1. Respiratory Organs of Plants—Lupwic Josr of Strass- burg communicates to Botanische Zeitung, Sept., 1887, some interesting facts concerning organs of peculiar shape found on the roots of certain palms, and their allies, and a few other plants. These organs are outgrowths from roots, they point upward into the air, and are generally characterized by having a swollen por- tion conspicuously different from the rest. Experimental study indicates that these organs, like stomata and lenticels, are of use in the aération of the plant. Jost suggests as a name for this group of organs, pnewmatodes. Among the possible cases alluded to by him but dismissed with hardly more than a word, is that of the enormous swellings on the roots of our Southern Cypress, Zaxodium distichum. Many years ago, Professor Shaler of Harvard stated to the present writer that he believed these excrescences of the Cypress of the South to be related in some way to the aération of the trees, since he had observed that where these had been submerged for a time by an overflow, the plants suffered and after a while died. Ina recent paper in the publications of the Museum of Comp. Zool. at Cambridge, Professor Shaler has given his views in detail, mak- ing out a strong case; so that we can feel little hesitation in re- ferring these extraordinary swellings on Taxodium to Jost’s new class of Pneumatodes. G. L. G 2. On a Conbination of the Auxanometer with the Clinostat. —At the writer’s suggestion, ALBRECHT, the well-known mech- anician at Tiibingen, has constructed a simple form of Auxanom- Botany. | 259 eter which can be well employed as a serviceable Clinostat. In addition to the strong axis which carries the equipment of the ordinary Clinostat, there is a smaller spindle driven by the same machinery and at such rates of speed as may be wished. Upon the latter spindle, the common form of registering drum is car- ried with absolute steadiness. Although, on general principles, one must view with more or less distrust an apparatus aiming to reach two ends so widely diverse as the two just mentioned, the present appliance has thus far worked satisfactorily. But for ordinary use in the class room, it is inferior as an auxanometer to either of the two simple and excellent ones figured and described in the Botanical Gazette by Professors Bumpus and Barnes. G. L. G. 3. Die natirlichen Pflanzenfamilien, von A. ENGLER UND K. Prantt. Leipzig, 1887. . (Now publishing in parts of which 12 have already been received).—The first number of this im- portant work and the promise given by it were noticed in this Journal last summer. The numbers which have since come to hand redeem this promise in the most satisfactory manner. The text exhibits care in its preparation even down to the minute treatment of the economic plants, and, although the parts are of unequal merit, all are of a high order, placing the work in the front rank. The illustrations are excellent throughout, and are lavishly used. Serial publications demand from the recipients of the successive parts a fair degree of patience, since in most cases, the separate articles come to the reader in a fragmentary form. Until the disiecta membra are all before one, it is difficult to tell whether they can be united to form a symmetrical structure : everything depends upon the skill in editing and the sense of proportion possessed by the editors. To them belongs the un- gracious task of contracting lengthy contributions and, more rarely, of suggesting increase in volume. — From all that appears in the present publication, up to the present time, the editors have performed their work with great judgment. Thus far the chief burden has fallen on Professor Engler. A mere enumera- tion of the leading contributions is all that can be justly given at this early stage in the progress of the publication. Professor Drude has finished the Palms in 93 pages, with seven pages addi- tional given to the Cyclanths; Haeckel carries the Grasses through 96 pages, with more to come; Engler has given 91 pages to Lili- aceae; Gymnospermae were treated of in 127 pages by the lamented Eichler, whose notes have received some additions from both the editors. Other contributions are from Pax, Hieronymus and Wittmack. In the twelve numbers received, consisting of about six hundred pages, there are 421 illustrations containing about two thousand single figures. Such a work is of the highest value to teachers of botany and ought even in its German form to command a large list of sub- scribers in this country. It is sincerely to be hoped that an Eng- lish translation may be early undertaken. G. L. G 260 - Scientific Intelligence. 4. Botanical Necrology of the year 1887, by Dr. Gray: his last work for this Journal.—The first two names in the American list belong rather to the obituaries of the preceding year. W. E. Toumre died in British Columbia, near the close of 1886, at an advanced age. ce. The mineral was not analyzed because of the small quantity available and because its identity was otherwise clearly estab- lished. | 2. ERINITE. Erinite occurs as a dark green crystalline lining of cavities, associated with and generally upon enargite, azurite, barite, or 300 Hillebrand and Washington—Minerals from Utah. clinoclasite. Crystals of olivenite are frequently scattered over its surface, which shows often a somewhat satiny sheen due to minute erystal facets. Hardness 4:5. Sp. gr. unde- termined. Because of its intimate association with azurite and olivenite it was very difficult to obtain pure material for analy- sis. Sample I contained 3-90 per cent of insoluble matter, not included in the analysis. Sample II was composed of a small lot of vitreous crusts, the only ones of the kind observed, which had been collected before shipment of the specimens and were thought to be erinite by Mr. Pearce, whose partial analyses of material similar to sample I are added, for comparison, unde JHBE Ve, IO III. Hillebrand. Pearce. a.» b. CuO 57:67* 57:51 56°56 57:43 ZnO 1:06 0:59 pee let CaO 0°32 0-51 0°43 Ree MgO tr. tr. ee ae AsoO5 Sono 31coi 32:07 32°54 P.O; 0°10 Loan ees HER H.O e02, es )oallfs) 6°86 7°67 Fe.03 0°14 0°20 0°85 se SO; Se Ses tr. eS 100°04 99°87 96°77 97°64. the water, are: CuO (CaO, Zn0) AseOs (P20s) H,0 if 5:08 5 1:00 : 244 1H 5°34 e 1:00 : 3°66 TIT. (mean) 513 : 1:00 : 2°87 If the weakly combined water be excluded from both I and II the ratio is brought considerably nearer to that derived from Turner’s approximative analysis,t i. e., 5:1: 2. It is uncertain whether Turner’s sample was air-dried or heated to 100° C. ' 3. TyRo.ire. (?) Regarding the identity of this species some doubt exists, as the analytical results obtained do not agree with those given by * Mean of 57°61 and 57°74. + Edin. Journ. Sci., ix, 95, 1828. Phil. Mag., iv, 154, 1828. Hillebrand and Washington—Minerals from Utah. 301 von Kobell* and Church +. In general appearance it seems to resemble tyrolite. It occurs in thin scales on quartz, but more often in radiating scaly masses, somewhat like the pyrophyllite from Graves Mt., Ga. It has a bright apple-green color, some- times with a tinge of blue; a somewhat pearly luster; a hard- ness of 2°5 (15-2 for tyrolite in the text books), and perfect cleavage. Under the microscope it showed little or no pleochro- ism and extinction parallel and perpendicular to the radial line. In convergent light the cleavage flake showed the ordinary biaxial figure with the dispersion p >v. Its double refraction is negative, the- acute bisectrix being perpendicular to the cleavage face, and coinciding with the erystallographic¢e. The obtuse bisectrix lies parallel to the radial direction of the erys- tal, but whether it corresponds with @ or } cannot be determined. It was unfortunate that a crystallographic investigation was im- possible, as our knowledge of tyrolite in this respect is of the most meager description. On heating it flies into fine fragments, which by gentle tapping of the tube collect into spongy masses. The mineral melts in the flame of a Bunsen burner. The Sp. grav. of sample I (containing 2°25 per cent of in- soluble gangue) was 3°27 at 203C. From sample II, which was the purest and best crystallized to be found, 1°25 per cent of gangue has been deducted. I 10 III. Hillebrand. Pearce. a b. Mean. CuO 45°20 45°23 45°22 46°38 42°60 ZnO see 0°04 0°04 Be: 0:97 (Fe,0;A1,03) CaO 6°86 6°82 6°84 6°69 9°10 MgO 0-05 rae 0°05 0-04 ee As.0O; 28°84 28°73 28°78 26522 27°87 PeO5 tr. ae tr. tr. reese H.O 17°26 prague 17°26 17:57 16°23 SO; ? ? ? 2°27 2°45 98°21 98°19 99°17 99°22 SO, was unfortunately not tested for in I. It may however reasonably be assumed to be present in about the same amount as in II, and if it be considered to be present as gypsum (CaSO,, 2H,O) the following molecular ratios are obtained. CuO (CaO) As.0; H,0 : I. HOW ¢ 0°94 : 6°80 or ENR) CPO Bi WANS ne 5°00 : 0°84 : 6°81 or MAB i a ctekay Bi) TLS} TI. 5°00 : 0:90 : 6°29 or HL TSS}. gy aster It appears herefrom that the As,O, is somewhat less and the H,O much less than required to satisfy the formula 5CuO, As,O,, 9H,O, derived from von Kobell’s (1. ¢.) whence he deduces the formula 5CuO, As,O,, 4H,0. me ing that Mg,P,O, is an error for Mg, As,0,, or for As,S,, which latter form it appears that arsenic was usually ati ated by him in minerals of a similar character, it is impossible to deduce the above given percentage for As, Oy. But considering the latter correct, and including the water lost in vacuo and at 100°, the composition is: Ud Ope ana a hs aaa A I so acca eC De 46:24 TNO roi ees Oe a era ED aay eel ORNS OE WISER, 27:05 1 GAO) Se ae ted en eu Nee te NOS ELA TR See yo i! 15-70 CaCO) te cet cameo ge ey ine Ge rae 41-01 100:00 which furnishes the molecular ratio CuO: As,O,: H,0 as 5°00: 1:01 : 7-43, not greatly differing from those derived from analyses I ye II above. * Naumaun-Zirkel, Elemente der Mineralogie, p. 540. Hillebrand and Washington—Minerals from Utah. 308 4, CHALCOPHYLLITE. This mineral occurs in the form of small hexagonal plates arranged in rosettes, differing from the radial arrangement otf the supposed tyrolite. It showed the same bright apple-green color, pearly luster, and perfect basal cleavage. An optical examination proved it to be uniaxial with negative double refraction. These crystals showed several planes replacing the edges, and measurements were made of them as far as possible. The angles did not agree very closely owing to the imperfection of 2. all the surfaces, but they were sufli- ciently exact to prove the presence of ay r (1011, 7), ¢(0112, -$.2), and two other. VES e rhombohedrons, new to the species, hav- i 4 ing the symbols w (1016, —1/2), and d (0113, -$f). The figure shows the habit of the erystals, but with d absent, this plane being only observed in one instance. The very rough angles obtained are given below : Observed. Calculated, Cn OOO LM OM =v (e tlgakog caw, 0001 1016=26° 107 26° 107 20” cae, 0001 ~ 0112=56° 51’ 5B°o 517 10” Br Oh MOOIL As ONE —AOT B04 : 44° 30’ 30” The above observed angles are the means of several measure- ments which vary among themselves from one to three degrees. The fair agreement in the first two results therefore is merely accidental, and no value can be attached to these measurements, which are inserted because the measurements of this species are extremely few. The mineral was not analyzed for want of sufficient material. On heating, it decrepitated as violently as the last mentioned mineral, and in the flame of the burner fused, though not with the same readiness. 5. CLINOCLASITE. The clinoclasite' occurs in two distinct habits, one dis- tinctly erystallized and the other in barrel shaped or globular forms. It is of a dark bluish green color, almost black by re- flected light, bright green by transmitted light. Streak and. powder bluish green. Specific gravity at 19° C., 4°38. (4:36 Pearce.) Hardness 2:5-3. At first sight these crystals seemed to be very promising and likely to afford good fundamental measurements for the species. But on further examination they did not come up to our expectations, ¢(001, O) and s(302, 3-2) being the only two planes giving even fairly good measurements. m (110, /), 304 Hillebrand and Washington—Minerals from Otah. rv (101, —1-2), ¢ (711, 1) and p (113, 4), the other planes observed, were all dull or rounded, and only capable of giving angles accurate enough to identify the forms. Of the planes above, ¢ and p are new to the species. Most of the crystals were apparently made up of two or more individuals in nearly par- allel position but inclined slightly in the zone c/b. A measure- ment in one case gave the angle 4° 10’, but as it is not the result of twinning, this angle of course is not constant and only shows the very slight inclination of the individual crystals. A consequence of this method of growth will be described later. The crystals were all simple; fig. 3, or a combination of that with 7, being the most usual. Occasionally the lower half of m 3. 4. 5. is replaced by ¢, as shown in fig. 5, giving the angle 13° 20’ (calculated 13° 17’) for mat. The new plane p (113) was ob- served in several crystals and is shown in fig. 4. The follow- ing angles were obtained for it: Observed. Calculated. cap, 0014 113 — ile 6’ 61° 267 30" SAD, 3027. —50% 14’ Ble VOZMOF pnp. 113 .113=82° 85° 487 The angles are merely approximate, but sufficient to establish the form. The crystals are for the most part elongated in the direction of the 6 axis, with a length of from 2 to 3", and show easy cleavage parallel to e. The other type of clinoclasite is interesting, as showing the consequence of the nearly parallel growth of the crystals men- tioned above. In some of the specimens the crystals are grouped about the } axis, with ¢ exposed. They are inclined a trifle in the zone ¢/b an‘d also in the zone @/d, thus rounding off - the group in two directions, but decidedly more in the latter zone, forming, with the elongation in the direction of 4, dis- . tinctly barrel-shaped forms. Occasionally the curvature in the zone ¢/d is carried still further, producing globular forms. In all cases ¢ forms the outer surface and the crystals are closely Gomes together, producing a bright and coarsely rough sur- ace. The material analyzed consisted of the globular masses men- tioned above, and was probably not as pure as the crystals and barrel-shaped forms. A trifling amount of insoluble matter (0°05 per cent) has been deducted. For comparison Mr. Pearce’s partial analyses are also quoted. Hillebrand and Washington—Minerals from Utah. 305 Te II. Theoretical Hillebrand. Pearce. Compo- a. b. Mean, a. b. sition. CuO wanes 62°34 62°04 62°44 61°68 61°22 62°65 Li Ona 0°06 0-04 0°05 Ais fats eels AssO5 --- 29°59 29°60 29°59 29°36 28°85 30°25 I2EOs eee 0:05 0:05* 0:05 be checb ee aan bye ete) BIO} Se tle 172 1:72 Tigo: 7:27 710 Fe,03 _- 0:12 0°12 0°12 AR EUOON Piha SHOW cscee 0:06 0:06* 0-06 Lies Wea eu 99°95 100713 100-03 98°35 97°34 100°00 These results reveal nothing worthy of remark except that the water, as in most earlier analyses, is found uniformly higher than that required by the formula 6CuO, As,O,, 3H,O, or Cu,[ AsO,],+3Cu[OH}.. 6. MIx1re. (?) On some specimens of ore, but apparently not in close asso- ciation with the other minerals mentioned, was a mineral occurring in delicate tufts of silky needles of a whitish to pale geenish color as described by Mr. Pearce (1. ¢., p. 151, under the title “New Mineral”). It was impossible to procure enough of the needles free from an underlying non-crystallized greenish coating of cavities for a satisfactory analysis. A good deal of the latter was necessarily included in the sample tested, but qualitative tests showed that both needles and coatings contained the same constituents. It is hardly to be doubted that both have the same centesimal composition. I. Hillebrand. 108 “ 6 Mean. Pearce. CUOEe tsar near 43°89 43°88 43°89 50°50 LAYS Oe ea Pe ie eT 2°79 2°62 2°70 Sees CaO cet Neos 0°26 0:26 0°26 3°19 IB Ogun sobs cies mies eae 1114 11:22 11:18 uae BING Ofc pnt aaeetpe ales tae athe 84 27:78 28°79 28°79} 27°50 5 Ore nes eh kn na bn Sete) 0:06 Bare 0:06 Ree 5 [pO i cere eth tes Mea 11°04 11:04 11°04 12°55 SHC pice a A Ee eee 0°36 0°48 0°42 EEE BSS Oi. i oie teres nate aw napa ae 0:97 ete 0:97 ia eal 98°29 99°31 93°74. That an error as to the CuO occurs in Pearce’s analysis is beyond question. The above results agree fairly well with Schrauf's analysis of mixite,t which contained 43°21 CuO, 13-07 Bi,O,, 30°45 As,O,, and 11:07 H,O, besides a little CaO and FeO, but the form of this mineral as given by Schrauf dif- fers from that of the present one, and its color is given as * Assumed the same as in a. + The higher value was undoubtedly nearer the truth than the lower. t Zeit. f. Kryst., iv, 277. 306 Hillebrand and Washington—Mimerals from Utah. emerald to bluish green. Schrauf’s number for the sp. grav (2°66) is unquestionably much too low. That of the material now analyzed was 3°79 at 234° C. When treated with dilute nitric acid it becomes at once covered with the brilliant white coating of bismuth arseniate so characteristic of mixite. The latter mineral is stated to belong to the monoclinic or the tri- clinic system, while the observations of Mr. Whitman Cross would indicate that the present one can belong to neither of those systems. He says:* “The needles are very slender, with a length of more than 1™™ in some cases, by 0°5™™. They are deeply striated vertically, and the erystal system could not be determined, although the extinction in polarized light makes reference to the tetragonal, the hexagonal, or the rhombic sys- tem necessary. ‘The index of refraction is high. Pleochroism. distinct, the colors observed being for the thicker anys, a (and 6) sea green, ¢ sky blue.” 7. PHARMACOSIDERITE. No analyses were made for want of sufficient material. 8. BROCHANTITE. This hydrous sulphate of copper occurs in two distinct types in the specimens examined. The first, or ordinary brochantite, is of a prismatic habit as is shown in fig 6. The erystals are dark green and transparent, but do not give good measure- ments, owing to the imperfection of the sur rface. The cleavage parallel to b (010, 2-2) is perfect. The measured angle of m6, 1104010 = 51° 46’, is only approximate, and differs con- siderably from Miller, who gives 52° 5’, and Schrauf, who gives 52°. * Proc. Colorado Sci. Soe., ii, 153. ° * C. D., Walcott—The Taconic System of Emmons. 307 The second type is like warringtonite from Cornwall, de- scribed by Maskelyne.* This variety was suspected by Mr. Pearce (loc. cit., p. 185). It is of a ight green color and has a curved double wedge-shaped habit. ‘The forms observed are shown in figs. 7 and 8. The crystals were poor for meas- uring, all the planes, with the exception of 6, being curved to a great degree. The crystals were none of them more than 2 or 3™™ long, with the relative proportions of the figures. They were implanted by 4; m, in fig. 7, was identified with cer. tainty, the angle for bAm being 52° approximately. The plane lettered & was very much curved in all cases and its sym- bol, consequently, is not known with exactness. It corresponds in its angles very roughly, it is true, to the #, 12.1.4, of Schrauf; some of the angles obtained from these crystals and the corresponding ones of Schrauf’s warringtonite being given here: Washington. Schrauf. D AIP OOS WS We ae Se 80°-82° 86° 437 mak, 110,12.1.4 = 45° AB a olulig bk, V2. 1.43 12.0 4— 75°-80° In most of the erystals of this type 6 was undulating parallel ; to ¢. Want of material forbade an analysis of this mineral, but blowpipe tests and the crystallographic examination establish its identity beyond doubt. Art. XXVIL+The Taconic System of Emmons,and the use of the name Faconic in Geologic nomenclature j\ by Cuas. D. Watcort, of the U. S. Geological Survey. ith Plate IIT. (Continued from page 242.) GEOLOGY oF THE Taconic AREA AS KNOWN TO Dr. Emmons. (1). The strata referred to the “Taconic System ;” (2). The stratigraphic position of the “ Taconic System.” Dr. Emmons began the study of the Taconic area in Berk- shire County, Mass., and from there extended his investiga- tions, to the north, into Bennington County, Vt., and to the west, into Washington and Rensselaer counties, N. Y.t In 1842,+ * Ch. News, x, 263, 1864. Phil. Mage., IV, xxix, 475. + ‘‘ My first business is to sketch a picture of the oldest of the sediments, as they are exhibited in a series which collectively constitute the Taconic System and as it is developed in the Taconic ranges of Berkshire and the adjacent country immediately north and south.” (Am. Geol., pt. 2, p. 5, 1856). £ Geol. N. Y., pt. 2, p. 144, 1842. 308 ©. D. Walcott—The Taconic System of Emmons. he proposed the Taconic System, with the statement that it was composed of five different rocks, as follows: “1. A coarse granular limestone of various colors which I have denominated Stockbridge limestone,” ete. “2. Granular quartz rock, generally fine-grained, in firm, tough, crystalline masses of a brown color, but sometimes white, granular and friable.” “<3, Slate, which for distinction I have denominated Magnesian slate,” ete. “<4, Sparry limestone, generally known as the sparry lime- rock.” “5. A slate, which I have named Taconic Slate, and which is found at the western base of the Taconic range. It lies adjacent to the Lorraine or Hudson River shales, some varieties of which it resembles,” ete. A section is given on page 145, fig. 46, to show that the “Taconic System” embraced all the strata between the gneiss on the east and the “shales of the Champlain group” on the west. The latter are represented as unconformably superja- cent to the “Taconic slate.” His second memoir appeared in 1844* as a pamphlet, pub- lished in advance of vol. i, of the Agriculture of New York, in which, in 1847, the subject matter was reprinted without change. The changes from the stratigraphic scheme of 1842 consist in placing the granular quartz at the base of the system, with the Stockbridge limestone conformably resting upon it. A theoretical sectiont is given to show the rela- tion of the various formations. . The crystalline gneiss is rep-) resented with (1), the Granular Quartz or brown sandstone resting upon it; then, in turn (2), the Stockbridge limestone ; (3), Magnesian slate; (4), Sparry limestone; (5), Roofing slate ; (6), coarse brecciated bed; (7), Taconic slate, and (8), Black slate. On the following page, the section shown by fig. 7 represents these beds as all having a high and uni- form dip to the eastward,t and with the Hudson river shales (9), ynconformably superjacent to the Taconic slate (8). When speaking of the lithologic characters of the system, Dr. Emmons says: “Taking one broad view of the whole sys- tem, it may be described as consisting of fine and coarse slates, * Aoric. N. Y., vol. i, pp. 45-112, 1847. The pamphlet of 1844 is very rare, as few copies were issued, and I shall make all references to its contents as re- printed in the volume of 1847, combining the dates as 184447. + Loe. cit., p. 62, fig. 6. t This is corrected for the ‘‘ Lower Taconic” rocks in the Section published in 1856 (Am. Geol., vol. i, pt. 2, p. 19), but all the strata of the ‘‘ Upper Taconic” are considered superior to the Stockbridge limestone. CO. D. Walcott—The Taconic System of Emmons. 309 with subordinate beds ‘of chert, fine and coarse limestone, and gray, brown and white sandstone. The geological map, prepared to accompany the memoir of 184447, bears the date of 1844 and is a reprint of the Geo- logical Map of New York, issued in 1842, with additional data on the geology east of the Hudson and Champlain valleys. The long, narrow range of the “ Taconic System” is colored drab in its extension from Canada to Westchester County, N.Y. There is no reference to the “Taconic System ” in the legend on the map, and the formations composing it are not distinguished. by different colors, the reason for which is ex- plained in the description of the map, published on page 361 of the Agriculture of New York, vol i, 1847.+ In 1856,t Dr. Emmons divided the “ Taconic System ” into — an upper and a lower division: the upper division taking the formations 4 to 8 of the section of 184447, and the lower division the formations 1 to 3; an arrangement that was re- peated in 1859 (Manual of Geology), when the name “ Mag- nesian slate” was replaced by that of “ Talcose slate.” In the diagram, fig. 10, the formations are represented in the order of succession given in 1856 ; and, on the map, the geographic area is given within which the typical localities of the various formations occur and also the extension of the latter to the north and south. This is the stratigraphic scheme of the “ Ta- conic System” as arranged by its author from the results of his latest field observations.§ “Granular Quartz” (Terrane No. 1, of section on side of map and fig. 10)—Dr. Emmons ealls the “ Granular Quartz” the basal member of the ‘Taconic System,” and, in his opin- ion, the base of the Paleozoic sediments on the North Ameri- can continent. He describes its occurrence in Vermont and follows it, with interruptions, across Massachusetts into the northeastern part of Dutchess County, N. Y., and also south into Putnam and Westchester counties. The stratigraphic * Loc. cit., p. 61. + The copy I have of this map was purchased by me from a second-hand book dealer, in 1876. I have reason to state that 3000 copies were originally delivered to the Secretary of State, of the State of New York, by the printers, and I think that copies can still be obtained from the said Secretary’s office, despite the pub- lished statement that the edition was stolen or destroyed. (See letter of Dr. Emmons to Prof. Jules Marcou: Am. Acad. Arts and Sci., vol. xii, p. 188, 1885, also copied by Dr. Hunt, Am. Nat., vol. xxi, p. 122, foot note 3, 1887). ¢ The first part of this volume is dated 1855. The second part, containing the description of the ‘‘ Taconic System,” was issued in 1856. § I shall not comment on the so-called Taconic rocks, as identified by Dr. Emmons in Canada, Maine, Rhode Island, Michigan, and the southern Appala- chian region. All those determinations rested on lithologic characters; and the strata referred by him to the ‘‘ Taconic System ” range from pre-Cambrian to the Niagara of the Silurian. | Agric. N. Y., vol. i, p. 86, 1847. 310 ©. D. Walcott—The Taconic System of Emmons. position was determined by its relation’ to the crystalline rocks beneath and the superjacent strata, as no fossils were known by him from the formation. A talcose conglomerate that is treated as a subordinate member of the “ Granular Quartz se- ries” is described as occurring between the quartzite and Primary, in several localities. 2 WSandstonesiand Slates 2 ss 8 : = —— —e SS Se Se ae Se ae ee S| 5 BSS ReckingsSlates= : SN = == — SS SS SS SS SS SS L S i ee ee oS = TSF = Se 5 S 5g = | BlacksS lates Ss 4 “FaléaseiS lates: = Soa eae Sea eee esi==s1 T La a pae Ra an 3 s Stockbridge Liméston L2G, a ie eee aae eae eee ower acon le of Lmmons. L, Fig. 10.—A tabular view of the strata as arranged by Dr..Emmons. The figures placed at the sides are equivalent to those used on the section on the side of the map. The dotted lines on the right side show the relation of the ‘‘Upper Taconic” to its geologic equivalent the ‘ Granular Quartz.” Conformably resting on the “ Granular Quartz,” on the north side of Graylock Peak, at the Hopper, he found a bed of “taleose slate,” 400 to 500 feet thick, which is represented in the table (fig. 10) by number 2. It appears to be the ex- tension of a formation of more than 2,000 feet in thickness that oecurs on the western side of the Taconic range. (See sec- tion on the map.) Stockbridge limestone (Terr. No. 3 of Section and fig. 10).— Upon the slates of Terrane No. 2a series of limestones and marbles are conformably superimposed that are called by Dr. Emmons the “Stockbridge limestone.” This includes all the limestones, “ good and bad, in connection with the bed known as marble.”” A good description of this terrane is given in the memoir of 184447, and again in 1856. It is assigned a thick- ness of 500 feet, in Saddle Mountain, Mass. C. D. Walcott—The Taconic System of Emmons. 311 Talcose Slates (Terr. No. 4 of Section and fig. 10). — These slates, which are called “Magnesian slates” in the re- ports of 18424447, were given the name “ Talcose slates” in 1856. A thickness of 2000 feet is assigned to them on the Taconic range and they are represented as conformably super- imposed upon the Stockbridge limestone. “Upper Taconic.’—In the scheme published in 1844~47 the Magnesian slate is succeeded by the Sparry limestone, Roofing slate, a coarse brecciated bed, Taconic slate, and Black slate, and on p- 138, Am. Geol., pt. 2, 1856, this succession is recognized. On page 49 (loc. cit.), however, the entire scheme is changed; the Black slate is placed at the bottom of the series and then, in succession, siliceous slates: slates and sand- stones, with thin-bedded blue limestones succeeded by thicker beds of sandstone ; blue, green, purple and red roofing slates, coarse sandstone and shale passing into conglomerates and brec- ciated conglomerates. “The latter terminate the series east- ward, and geographically near the Hoosick roofing slates. In the foregoing brief enumeration in the ascending order, the rocks follow each other in a conformable position, and begin- ning with the thin black slates, end in thick bedded sandstones and conglomerates,” (loc. cit., p. 50). In this re-definition of the ‘‘ Upper Taconic,” the Sparry limestone is no longer considered as belonging to it, and I have failed to find it mentioned subsequently as a distinct formation of the “Upper Taconic.” The sparry limestone spoken of in describing the “ Upper Taconic” section crossing Washington County, refers to the thin interbedded sparry limestones, in which I have found Olenellus and other Middle Cambrian fos- sils. The sparry limestones west of Hoosick Falls are referred to the Lower Silurian and removed entirely from the “Taconic System.” As is shown by Professor Dana, Dr. Emmons, in 1842, called the Sparry limestone the oldest of the Taconic limestones, and, in 1844, he placed it beneath the Taconic slate and above the Stockbridge limestone.* In 1856,+ however, a section was published showing the Taconic Range by C and, at its western base, the limestone (2) is identified with ie Stockbridge lime- stone (2), of B (Graylock Peak). What Dr. Emmons intended by this, and a he did not mention the change in the text, is not explained by him. Professor Dana called my attention to it by letter, and says that he accepts the evident meaning given by the section, which is, that Dr. Emmons identified the Sparry and Stockbridge limestones as one formation. With our pres- ent knowledge, this explanation is the only one open to us. * This Journal, III, vol. xxxiii, pp. 415, 416, 1887. + Am. Geol., vol. i, pt. 11, p. 19, fig. 2: 312 0. D. Walcott—The Taconic System of Emmons. In 1859 the section is republished,* but the numbers are omitted from all the formations except those of Graylock Peak. Whether the omission was by design or accident is unknown. In the black slates, at the summit of the “ Taconic System” of 184447 and at the base of the “Upper Taconic” of 1856, Dr. Asa Fitch found a few fossils which he gave to Dr. Em- mons, who described two species in the memoir of 1844~47, under the names of Llliptocephala asaphoides and Atops tri- lineatus. In 1859 Dr. Emmons compared these fossils with the Primordial fauna of Barrande, and established their position in the stratigraphic series on paleontologic evidence.t Their ref- erence to a pre-Potsdam horizon, in 1844—’47 and 1856, was on the supposed stratigraphic position of the beds in which they occurred. féswmé.—lIt is not necessary to repeat the full and accurate lithologic descriptions of the five terranes (fig. 10) mentioned by Dr. Emmons in 184447 and 1856. They are grouped in fir. 10 to represent his view of their succession within the “Taconic System.” | 2. Stratigraphic position of the “ Taconic System.”—Dr. Emmons founded the “ Taconic System ” under the belief that it was composed of older formations than those of the New York Lower Silurian, the base of which was then the well- known Potsdam sandstone. In the memoir of 1842, he says: “ But I have, at the head of this section, asserted that the slates and masses of the Taconic System are not related to, or connected with those of the Champlain group. By this I mean that they are not the same rocks in another condition.” t Again he says: “ They are to be considered, however, as fur- nishing us with a knowledge of that state which immediately preceded the existence of organic beings.” § After further field study his views became more positive in regard to the relation of the Taconic to the Lower Silurian rocks. He says: “I shall take the broad and distinct ground that the Taconic System oc- cupies a position inferior to the Champlain division of the New York system, or the Lower division of the Silurian system of Mr. Murchison.” | “1. Position.—lIt rests unconformably upon primary schists, and passes beneath the New York system, the oldest and infe- rior members of the latter being superimposed unconformably upon the Taconic slate.”4{ These views were sustained in his publications of 1856, 1859 and 1860. On the section, accompanying the memoir of 1844—47, pl. 18, Section I, the strata of the ‘‘ Taconic System ” all dip con- * Manual of Geology, p. 85, fig. 60. + Manual of Geology, p. 87, 1859. + Geol. N. Y., pt. 2, p. 138, 1842. § Loe. cit., p. 164. | Agric N. Y., vol. i, p. 55, 1847. { Loe. cit., p. 108. C. D. Walcott—The Taconic System of Emmons. 318 formably to the eastward. On the east they rest unconforma- bly on the primary and, on the west, the Calciferous and Hud- son terranes are represented as unconformably superjacent to the Taconic slates. Dr.. Emmons says: ‘This section may be regarded as one of the best for exhibiting and proving the entire independence of the Taconic System from the Primary below and the New York system above.” * Two sections published in 1859+ may be taken as express- ing his latest views of the relations of the different parts of the “Taconic System,” in its typical area, with the exception of the ‘“Upper Taconic” and the Lower Silurian (Ordovician), on the western side. In these sections, the “Lower Taconic” forms a synclinal with the “ Granular Quartz” at the base and then the Stockbridge limestone and Talcose slates, respectively superjacent, the ““ Upper Taconic” being entirely disconnected from the latter. He held the view, from the first, that the eastward dip of the greater part of the strata of the ‘Taconic System” resulted from successive uplifts, ‘which, in consequence of the confined position of the rocks, have often produced local foldings and plications of the strata.” { His view of the extent and character of the uplifts was subsequently changed, as is shown by his representation of the position of the sparry limestone in 1842,§ 18448 and 1855. In the memoir of 1856 several sections were illustrated and described to show the unconformity ‘between the Taconic slate and the Calciferous sandrock, and thus establish the inferior position of the ‘‘ Taconic System ” to the Lower Silurian (Or- dovieian) strata. These sections will be spoken of again, under the head of ‘‘ Discussion and Comparison.” Dr. Emmons correlated the ‘Taconic System” with the Cambrian system of Sedgwick, in his first memoir of 1842, in the following words: || “‘ The Taconic rocks appear to be equiv- alent to the Lower Cambrian of Prof. Sedgwick, and are alone entitled to the consideration of belonging to this system, the upver portion [of the Cambrian—C. D. W.] being the lower part of the Silurian System.” 4 i Again, in the memoir of 1844—47, he says, when speaking of the proposed abandonment of the Cambrian System by Eng- lish geologists: “.... were it not for a single fact, the * Loe. cit., p. 366. + Manual of Geology, p. 85, figs. 58 and 60. t Geol. N. Y., pt. 2, p. 142, 1842. S See Professor Dana, this Journal, 3d Ser., vol. xxxili, p. 415. | Geol. N. Y., pt. 1, p. 163, 1842. { Dr. T. S. Hunt (Am. Nat., vol.xxi, p. 124, 1887) interprets this passage to prove that Dr. Emmons in 1842 correlated the upper portion of the Tatonic with the Lower Silurian of Murchison, but, as I read it, Dr. Emmons refers the Upper Cambrian, not his Taconic, to the Lower Silurian. Am. Jour. Sct.—Turrp Series, Vou. XX XV, No. 208.—APRIL, 1888. 19 314. ©. D. Walcott—The Taconic System of Emmons. writer would freely acquiesce in the decision, so far as the British rocks are concerned. This fact is found in the exist- ence of peculiar fossils on both sides of the Atlantic, which, so far as discoveries have been made, are confined to the slates of the Cambrian and Taconic systems; and now the great ob- ject of the writer is to show that the above question has not been settled right, or according to the facts; or, in other words that the Taconic rocks are not the Hudson River slates and shales in an altered state, or that all the Cambrian rocks are not Lower Silurian.” * In the following pages observations and deductions there- from are given to support the above statement in relation to the “ Taconic System,” but nothing further is said of the fos- sils from the Cambrian system, and I am at a loss to know to what species the author referred. Reference is made to the Cambrian sections of Sedgwick, in 1856, to show that although the Cambrian slates are conformably beneath the Coniston limestone bearing Lower Silurian fossils, and hence may be re- ferred to the Silurian, the Taconic rocks are unconformably beneath the equivalent Calciferous sandrock of the New York series and cannot be included with the Lower Silurian.+ Among the letters of Dr. Emmons, published by Prof. Jules Marcou,t is one, dated November 19, 1860, in which he says :§ «. ... I do not think him [referring to Barrande] right in maintaining that his Primordial group is a part or parce! of the Silurian: . . . . the Lower Silurian is strictly unconform- able to every part of my Taconic series, and this series is ... . separate and distinet from Silurian.” after all, his Primordial group is only Lower Silurian. I con- ceive we have exactly his Primordial group in the band of slates containing the Paradoxides. But this band is only a very narrow belt of beds.” In a letter dated December 28th, or 29th,| he says, when speaking of the announcement of the Hwronian System by Logan: “I claimed that the Huronzan was the Taconic Sys- tem... Are you aware that most, if not all, of those beauti- ful graptolites Mr. Hall refers to the Hudson River group be- long to the Taconic System ?” Again, in a letter dated January 23d, 1861:4 “The acknowl- edgment of the Primordial of Barrande im this country is really one of the finest and best facts in geology, making a codrdi- nation of American and European rocks so complete and har- MOntous.”” * Agric. N. Y., vol. i, p. 49, 1847. § Loe, cit., p. 186. + Am. Geol., vol. i, pt. 2, p. 90, 1856, | || Loe. cit., p. 188. { Proc, Am, Acad. Arts and Sci., vol, xii, 1885, 4] Loe. cit., p. 1990. 0. D. Walcott—The Taconic System of Emmons. 315 In commenting upon Professor Marcouw’s reference of the Potsdam sandstone to the “Taconic System,” he objects to such references on stratigraphic grounds, as is shown by his letter of January 28th, 1861. These later letters of Dr. Emmons prove that he considered the “ Taconic System ” to include the Huronian of Logan and the graptolite-bearing shales of the Hudson valley, from his letter of November 20th, 1860, he also included the Para- doxides beds of the ‘‘ Upper Taconic” which equal the Pri- mordial group of Barrande, which “is only Lower Silurian,” and declared that “the Lower Silurian is strictly unconform- able to every part of my Taconic series.” Despite the statements made in the preceding paragraph, I think we may say that Dr. Emmons regarded the original “Taconic System” as stratigraphically unconformable and sub- jacent to the Potsdam sandstone of the Lower Silurian of the New York section and believed it to rest unconformably upon the crystalline gneiss at its base and to form a great system of sedimentary rocks between the gneiss and Potsdam sandstone. CoMPARISON AND Discussion. Comparison.—A comparison of the geology of the Taconic area as known at the present time with the geology of the same area as known to Dr. Emmons develops several points of agreement. His lithologic descriptions are usually easily verified ; and the general dip and arrangement of the strata within the “Taconic System” are the same with the exception of the relations of the strata referred to the “Lower” and “Upper Taconic.” | The points of disagreement are: the identification of the geologic age of the formations of the “ Lower Taconic ;” the stratigraphic relations of the “ Lower” and “ Upper Taconic ;” the stratigraphic relations of the “Upper Taconic” and the superjacent Silurian formations, and the value of the strati- graphic and paleontologic identifications of the age of the “Upper Taconic” slates. 1. Dr. Emmons considered the “ Lower Taconic” to be composed of three non-fossiliferous pre-Silurian formations— “Granular quartz, Stockbridge limestone and Taleose slates” (see fig. 10) that were unconformably superjacent to the crystal- line gneisses beneath and conformably subjacent to a great series of slates, forming the “ Upper Taconic,” that, in turn, were unconformably subjacent to the lowest of the Lower Silurian formations, the Potsdam sandstone. We now know that the base of the “ Taconic System,” the “ Granular Quartz,” contains fossiis that prove it to be the geo- logic equivalent of the greater portion of the “Upper Ta- 316 OC. D. Walcott—The Taconic System of Emmons. conic ;” also, that it is the arenaceous deposit that accumulated along the pre-Paleozoic shore while the siliceous, argillaceous and calcareous muds, now forming the “ Upper Taconic,” were being deposited to a greater depth off the immediate shore line. This entirely negatives the conclusion of Dr. Emmons, that the “Upper Taconic” slates were superjacent to the | “Fig. 11. ‘Lower Taconic” rocks. 2. The second: formation, the “ Stock- bridge limestone,” has afforded fossils -that prove,it to be the equivalent of the Trenton, Chazy and Calciferous lime- stones of the Lower Silurian of the New York section, and it is not, as claimed by Dr. Emmons, a peculiar pre-Silurian ope of limestone. Conformably resting upon the es Sod nales limestone” the “ Talcose slates” (Terr. No. 4) occupy the strati- graphic position of the Hudson Terrane, in the New York section, and a species of graptolite, abundant in the Hudson Terrane, occurs in the “ Talcose slates ” near Hoosick, N. Y. We have next to consider the rela- tions of the “ Upper Taconic” slates to the superjacent Silurian formations and the value of the stratigraphic and pale- ontologic identifications of the age of the “Upper Taconic.” In the first published section* of the “Taconic System,” the “Shales of the Champlain Group” are represented as resting uncontormably against, and on, the Taconic slates. This is repeated in the section published in 1844-47.+ These two sections are largely theoretic, but, on page 89 (loc. cit.), Dr. Emmons gives a section of Bald Mountain, in the town of Greenwich, Washington County, N. Y., which is here reproduced ig Wit) = This section is intended to show the unconformity between the Taconic slates, b, 6’, 6”, and the Calciferous formations, d, c and d’, it being assumed by Dr. Emmons that the slates, 6, 6’ and 6”, * Geol. N. Y.; Rep. Second Geol. Dist., p. 145, fig. 46, 1842. + Agric. N. Y., vol. i, p. 63, fig. 7, 1847. C. D. Walcott—The Taconic System of Emmons. 317 were identical, and that d’ was a mass of the Calciferous sandrock of the New York section, and, also, the mass repre- sented by,c. I began the investigation of this section, in 1887, by searching for fossils in the various formations, and then studied its stratigraphy. The result is given in the section represented by fig. 12. I found that the blue limestone, ¢, of figs. 11 and 12, extends beneath the shales and limestones cap- ping the mountain and that it is interbedded in the shales and considerably broken and displaced on the south edge of the mountain, toward the fault line, as shown in fig. 12. Leper- ditia fabulites was found in it, on both the west and south side of the mountain. The true Calciferous sandrock, of the New York section, is shown at E, interbedded in the shales, S and X. In the limestones, d, forming the summit of the mountain, in fig. 11, I found Lingulella celata, Linnarssonia Taconica, Obolella sp. undet., Hyolithellus micans, Microdis- cus speciosus and Olenellus Thompsoni: all of which are Mid- dle Cambrian species and characteristic of the slates, 5’’, in fig. 11, east of the mountain. Dr. Emmons identified this mass of strata, d’, with the Calciferous sandrock on lithologic characters, overlooking the fact that a similar rock might occur in his Taconic series. Two miles to the north, on the farm of D. Walker Reid, this belt of calciferous rock is over 600 feet thick, it contains a characteristic Middle Cambrian fossil, Hyo- lithellus micans, and is conformably subjacent and superjacent to shales and limestones, containing over fifteen characteristic species of Middle Cambrian fossils. FIGURE 12.—Section of Bald Mountain from the south. The profile of the mountain and position of the Cambrian and Lower Silurian rocks are taken from a photograph. The “ Upper Taconic”=Cambrian slate, sandrock and limestone are shown to the right of the fault, and c=Chazy limestone ; x=dark shales, interbedded between c¢ and the Calciferous sandrock, HE; s=dark argillaceous shales beneath the Calciferous sandrock. The section of Bald Mountain proves that the strata of the “Upper Taconic” are there pushed over on to the Chazy Ter- rane, and that the “ Upper Taconic” is not unconformably sub- jacent to the latter or to the Calciferous sandrock. To the north of Bald Mountain, about two miles, a somewhat similar mass of limestone to that of ¢ is adjacent to the fault 318 ©. D. Walcott—The Taconic System of Emmons. line and contains: Orthis testudinaria, Strophodonta alter- nata, Maclurea and other gasteropods, Calymene senaria and fragments of Asaphus platycephalus. Details of all the ex- posures observed where the “‘ Upper Taconic” shales and the rocks of the Lower Silurian come in contact will be given in a report on the geology of Washington and Rensselaer counties. Another section,* taken by Dr. Emmons just east of the village of Whitehall, is reproduced in fig. 13. The object of this is to show the presence of a mass of calcareous sandrock, d’, resting unconformably upon the Taconic slate, which Dr. Emmons identified as the Calciferous formation of the Lower Silurian. I studied the section in 1886, also in 1887, and found Cambrian fossils, represented by the heads of the Olenellus and fragments of Ptychoparia, imbedded in the sandrock, @’, and also found the strike and dip of the sandrock and shales to a NINN FIGURE 13, a, a.— Easterly prolongation of the mountain, which is surmounted by the Calciferous sandrock: 6 b, Tertiary clay; c, c, Taconic and black slate; d, d, Calciferous sandstone, unconformable to the Taconic slates, and dipping southeast at an angle of 40-45". (After Emmons.) be conformable. Another section on the same paget is en- tirely within the Champlain series on my map and west of the great fault line. It is 30 miles north of Bald Mountain and in the township of Whitehall. I found the Potsdam sandstone at its base, in the village of Whitehall, and then, superjacent to it, the Calciferous Terrane, with a band of dark argillaceous shale, lithologically similar to that of the Hudson Terrane, between it and the superjacent Chazy limestone. Resting on the Chazy limestone there ‘is a second band of dark shales, 175 feet thick, that is subjacent to the Trenton limestone, and the latter is subjacent to the argillaceous and sandy shales of the Hudson Terrane. . The strata of the entire section are conformable; and the limestones were identified by contained fossils: East of the shales of the Hudson Terrane, the existence of the great fault line is shown by the presence of strata, resting against, and on, the Hudson Terrane, that carry Middle Cambrian fos- sils. These interbedded shales, between the limestones, and, also, the Hudson shales, were considered, by Dr. Emmons, to be of Taconic age, and the limestone to lie unconformably above them. * Agric. N. Y., voli, p. 56, fig. 2, 1847. + Loe. cit., p. 56, fig. 3. ¢ One fact, not recognized by Dr. Emmons at Bald Mountain or along the great fault line, is that in many localities belts of dark argillaceous shale occur between the Calciferous, Chazy and Trenton limestones; that, in others, one or more of these formations is entirely a shale formation, and that the Potsdam Ter- C. D. Walcott—The T ‘aconic System of Emmons. 319 Another illustration of the supposed overlap of the Cham- plain upon the Taconic Terrane is given in the American Geology, pt. 2, p. 72, fig. 12. It is in the township of Green- bush, opposite Albany, N. Y, on Cantonment Hill. There a mass of the Trenton limestone is caught on the line of the great fault separating the Champlain and Cambrian strata, as at Bald Mountain and other places in Washington county, and, also, in Vermont. The strata of the Hudson and Trenton Terranes are broken and displaced, but there is no evidence that the Trenton was deposited upon the upturned edges of the Cambrian or “ Upper Taconic” slate; and, on the line of the same fault, 20 miles to the south, in the township of Schodack, Mr. 8. W. Ford discovered an unconformable contact between the dark-drab siliceous and micaceous shales of the Cambrian and the dark argillaceous shales of the Hudson Terrane.* Mr. Ford kindly took me to the locality which he has so well described, and I saw the “hade” of the fault, the slickensides on the op- posing surfaces, and broke out graptolites from the Hudson shales beneath, and within six inches of, the fault line. A short distance south the limestones interbedded in the dark- drab shales gave us an abundance of characteristic Middle Cam- brian fossils. For the details of this overthrust of the Cam- brian upon the Hudson Terrane, see Mr. Ford’s paper. Dr. Emmons illustrates another sectiont that shows the same errors of observation as in the figure of the section at Can- tonment Hill. Again, in fig. 22, of the section at Snake Mountain, in Vermont, the error made at Bald Mountain is repeated, for it is now well known that the supposed overlying Calciferous (?) sandrock (“ Red sandrock”) is a stratum of the Cambrian pushed over on to the Lower Silurian Terrane,§ and not a Lower Silurian formation, unconformably superja- cent to the ‘“ Upper Taconic” strata. All the overlyiag limestones that he mentions as unconform- ably overlying the Taconic rocks, with the exceptions noted, where they contain Middle Cambrian fossils, are west of the rane, off shore, was originally deposited either as a calcareous or argillaceous mud. It was owing to this oversight that he frequently identified the shales of the Champlain series as those of the Taconic. Another phenomena not understood by him, was the creeping or protruding of shales from beneath heavy masses of limestone, on account of the pressure squeezing the shales out aud turning them up. In this way many of his non-conformities of dip appear to have been erro- neously observed. In many instances he did not recognize the lithologic differ- ences between the great mass of his Taconic slate and that of the Hudson Terrane. The black shale (marked ‘“‘ Taconic,” in the Bald Mountain section, 0, 0’, fig. 11) is not similar to the shale containing the trilobites, east of the great fault, yet he identified them as lithologically the same formation. * This Journal, vol. xxix, p. 16, 1885. + Am. Geol., vol. i, pt. 2, p. 79, fig. 14, 1856. t Loe. cit., p. 87. $ This Journal, III, vol. xiii, p. 413, 1877. 320 ©. D. Walcott—The Taconic System of Emmons. fault line separating the Cambrian and Silurian Terranes; and the shales west of the fault belong to the Silurian, not to the “Upper Taconic” Terrane. The line of outcrop of the Cam- ‘brian Terrane is well marked, and I have endeavored to locate it accurately on the map. The great Appalachian fault sepa- rates the Potsdam and other Silurian rocks from the Cambrian ; and nowhere on the western side of the Cambrian Terrane, to my knowledge, either in New York or Vermont, is there a deposition contact, either conformable or unconformable, be- tween the rocks of the ‘Taconic System” and the Potsdam or other Silurian terranes. I have examined all the localities cited by Dr. Emmons and, later, by Professor Marcou and, in every case, the great fault separates the strata of the two sys- tems. In fact, the Taconic usually rests on the Silurian strata as the result of the overthrust from the east; and, as will be shown in my report on Washington County, N. Y., the strong- est proof of the presence of a fault line is shown by the me- chanical disturbance of the Cambrian strata, on the eastern side of the fault. . That the Taconic slates are unconformably pre-Potsdam, is yet to be proven in any area known to Dr. Emmons, either in New York or Vermont. Where they pass beneath the shale representing the Potsdam horizon, beneath the Stockbridge limestone in the Taconic Range, they are conformably pre- Potsdam, but this fact was unknown to Dr. Emmons.* fésumé.—As the result of these comparisons, we find that the “‘ Lower Taconic” is essentially a repetition of the lower Silurian (Ordovician) section of the Champlain valley. It differs in lithologic details and in having a less abundant fauna in the typical Taconic area The “ Upper Taconic” is found to be conformably aubincent to the “ Stockbridge” limestone of the “ Lower Taconic,” and to include the Potsdam horizon at or near its upper portion. Its base is not unconformably subjacent to the Lower Silurian Terrane, as maintained by Dr. Emmons and Professor Marcou. The value of the paleontologic identification by Dr. Em- mons of the ‘“ Upper Taconic” slate as a pre-Potsdam forma- tion will now be considered. * Professor Henry I). Rogers, in his address before the meeting of the Asso- ciation of American Geologists and Naturalists, held at Washingtou, in May, 1844, said, when speaking of the unconformity claimed by Dr. Kmmons between the Champlain and Taconic rocks: ‘‘I must take the liberty of expressing my disbelief of any such unconformity, and of observing that in the prolongation southwestward of this altered and plicated belt as far as the termination of the Blue Ridge in Georgia, a distance of 1000 miles, no interruption of the general conformity of strata has ever met the observation of my brother or myself.”— (Amer. Jour. Sci., I, vol. xlvii, p. 152, 1844). 5 C.D. Walcott—The Taconic System of Hmmons. 321 On page 63, of the Agriculture of New York (vol. i), under the heading “ Black Slate,’ Dr. Emmons says: “I shall de- scribe the rocks in the descending order: and by so doing, I eommence with the mass of which there is some doubt whether it ought to be considered as a distinct rock or merely the upper portion of the Taconie slate; still I am disposed to re- gard it now as a separate and distinct rock, forming, so far as examinations have been made, the highest member of the Taconic system. Circumstances which have led to the separa- tion of this from the rock referred to are of an interesting character; interesting particularly as being connected with the discovery of crustaceans where they were least expected.” Dr. Asa Fitch found the fossils from the “ Black Slate,” in 1843, and gave them to Dr. Emmons, who described two spe- cies of trilobites under the names of Atops trilineatus and Etliptocephala asaphoides,; the first he thought to be an inter- mediate genus between the Calymene and Triarthrus; of the second, Llliptocephala asaphoides, he compared parts with similar parts of the Asaphus tyrannus, of the Lower Silurian of England.* On page 68 of the same memoir, under the head of “ Fossils peculiar to the Taconic Slate,” he describes two species of Annelid trails: one from the Green Taconic slate, and the other from the sandstone in Washington County. He follows this with a description of nine species of what appeared to be trails from the slates of Waterville, Maine. It appears from this that Dr. Emmons considered these various trails to be “ fossils peculiar to the Taconie slate,” and that the trilobites which he described he did not consider, at that time, as typi- ical of the ‘Taconic System,” for he says (loc. cit., p. 64), in speaking of the ‘ Black Slate :”. “Assuming that its fossils are distinct from the fossils of this and other systems,” ete. In his conclusions, he says:+ ‘‘ The Nereites and other fos- sils of the Taconic slate are unknown in any of the members of the Champlain group. In addition to which, it is impor- tant to bear in mind the fact that in this group the Mollusca of the New York system are also wanting.” In 1856,t he referred the Black slates to a position above the Talcose slates of the “Lower Taconic,” thus making them the base of the “ Upper Taconic” series. On page 98, loc. cit., the argument is made that the “ Taconic System” is peculiar in its contained organisms, and that he has the right to con- sider the absence of certain Silurian fossils as evidence that the Taconic was not of Silurian age. As has been shown in the first part of this paper, the limestones of the “ Lower Ta- # Toe, Cit., pp, 645 65.0 0. t Am. Geol., pt. 2, p. 49, 1856. + Loe. cit., p. 108. 322 C. D. Walcott—The Taconie System of Emmons. conic” carry characteristic Lower Silurian (Ordovician) fossils, as, also, do the shales overlying the limestones. In 1859 (Manual of Geology, p. 87), Dr: Emmons for the first time compared his Hlliptocephala asaphoides with the genus Paradoxides, of Barrande’s Primordial Zone, stating that the Taconic Paradoxides is also Silurian, and hence it is shown that the Primordial Zone, in Bohemia, is in codrdina- tion with the upper series of Taconic rocks. This statement is the first known to me upon which, either by paleontologic or stratigraphic evidence, Dr. Emmons could base his assertion that any portion of the “Taconic System” was of pre-Pots- dam age. The want of clearness in his views is well shown by the extract already quoted from his letter of Nov. 20, 1860, pub- lished by Prof. Marcou. “ His [Barrande’s] Primordial group is only Lower Silurian. I conceive we have exactly his Primordial group in the band of slates containing the Para- doxides.”— What becomes of the stratigraphic break between the Lower Silurian and Taconic rocks if the “ Black slates ” are still retained in the “Taconic System,” remains unex- plained. If removed the fossils go into the Lower Silurian with it. Dr. Emmons described several species of graptolites* from the “ Taconic System,” the majority of which are now known to also occur in the Hudson Terrane, in the valley of the Hudson. On the map, I have given the distribution of the Hudson Terrane in the Taconic area, as determined by strati- graphic and paleontologic evidence. It is in the central belt, carrying the red slates, that the graptolites occur which led Dr. Emmons to include, as a matter of necessity, if he put ‘the red slates in the Taconic, the dark, argillaceous shales of Hudson Terrane at Troy, Albany, and Baker’s Falls, in the Hudson Valley, for they contain the “beautiful graptolites”+ referred to by him in 1860. At Albany, N. Y., however, the graptolite beds contain a characteristic Trenton- Hudson fauna. This removes a considerable portion of the “ Upper Taconic ” strata from the “ Taconic System.” * Am. Geol., vol. i, pt. 2, pp. 104-111, 1856. + See letter to Prof. Jules Marcou; Proc. Am. Acad. Arts and Sci., vol. xii, p. 188, 1885. + Mr. CO. E. Beecher found three of the same species of graptolites (Climaco- graptus bicornis, Dicranograptus ramosus and Diplograptus mucronatus) as those found by me in the ‘Taconic Slates” of Washington and Rensselaer counties, asscciated with Brachiopoda, 5 species; Lamellibranchiata, 16 species; Ptero- poda, 2 species; Gasteropoda, 3 species; Cephalopoda, 2 species; Annelid, 1 spe- cies; Crustacea, 1 species, and Trilobita, 2 species. For names of species, see Mr. Beecher’s paper. (Thirty-sixth Ann. Rep. N. Y. State, Mus. Nat. Hist., p. 78, 1884). C. D. Walcott—The Taconie System of Emmons. 328 - Résumé of the Paleontologic Hvidence. (1.) The trilobites described in 1844-47, from the “ Black Slate,” were referred to the highest member of the ‘“ Taconic System,” on stratigraphic evidence. (2.) The same trilobites were referred to the lowest member of the ‘Upper Taconic,” on stratigraphic evidence, in 1856. (3.) In 1859 they were for the first time referred to a pre- Potsdam position by comparison with a fauna whose position had been stratigraphically determined in relation to the Silu- rian fauna. (4.) The Nereites and other trails with the exception of the two from Washington County, N. Y., described as typical of the “Taconic System,” have not yet been stratigraphically located in the geologic series. (5.) The graptolites referred to the “ Taconic System” form a portion of the fauna of the Hudson Terrane. Discussion.—There is not much opportunity for a discussion of the geologic age and position of the “ Lower Taconic” rocks. The thorough work of Professor Dana practically set- tled those points before I began my investigation. Dr. T. S. Hunt opposed Professor Dana’s conclusions, basing his dissent pn the result of his own studies of the geology of southeastern Pennsylvania and, on his acceptance of certain theoretic views in regard to the lithology of the “ Lower Taconic” rocks. He argued that the “ Lower Taconic” was the typical Taconic Sys- tem and of Archean age,* and that Professor Dana’s interpreta- tion of the stratigraphy was not sufticient, without the aid of fos- sils, in the typical Taconic region, to establish the Lower Silurian age of the Stockbridge limestone or the crystalline marbles of the Lower Taconic. With the facts presented in this paper, how- ever, I do not think that Dr. Hunt can claim support for his’ views without first substantiating them by researches in the Taconic area, a matter that he has apparently not. given his attention, + heretofore. *(“Taconie Question in Geology ;” Min. Physiology and Physiography, p. 682, paragraph 92, 1886). ‘92. Considering the pre-Cambrian age of the Lower Taconic to be established, as well as its distinctness alike from the older crystal- line rocks below and from the Cambrian series above, to which Emmous had given the name of Upper Taconic—it was proposed by the writer. in 1878, to restrict the term Taconic—for which the alternative name of Taconian was then suggested,—to the Lower Taconic of Emmons.” For other views held by Dr. Hunt, see Am. Jour. Sci., 3d ser., vol. xxxiii, pp. 417, 418, 1887. +Some of Dr. Hunt’s errors consist: 1. In relying upon a lithologie theory based upon observations made far distant from the Taconic area 2. His accept- ance of Dr. Emmons’s theory of the stratigraphic position of the “ Lower Taconic” strata without persona] investigation when it was well known that all of Dr. Emmons’s contemporary geologists opposed the ‘ Taconic” theory. 3. His assum- ing that it was largely personal opposition to Dr. Emmons that led all geologists who investigated the Taconic area to decide against the “Taconic” theory. 4. His ignoring all stratigraphic and paleontologic evidence published by Professor 324 0. D. Walcott—The Laconic System of Emmons. Professor Dana was in accord with the opinion of Professors W. B. and H. D. Rogers, Edward and C. H. Hitchcock, W. W. Mather and James Hall, as well as with the results of his own field studies, when he ealled the ‘“* Granular Quartz” Pots- dam, the “Stockbridge limestones, Lower Silurian (Calciferons- Chazy-Trenton) and the overlying “'Talcose” shales the Hudson River formation. He held the opinion that the “ Lower ‘l'a- conic’ was the typical “Taconic System,” as first defined in 1842, but as that was proven to be Lower Silurian in age the “laconic System” could not longer be recognized. In opposi- tion to this Professors Marcou and Winchell argue that if the “Lower Taconic” was of Lower Silurian age the “Upper Ta- conic” contains Primordial fossils and is, therefore, equivalent to the Cambrian; and, as the discovery of fossils in the “Upper Taconic” was made before typical Primordial fossils were published from Sedgwick’s Cambrian System, the name Taconic had priority over that of Cambrian and should be used in place of it to designate the strata containing the First or Primordial fauna of Barrande. I was influenced by the statement made by Dr. Emmons that the slates of the ‘“ Upper Taconic” were unconformably beneath Lower Silurian strata, and, also, by the views of Pro- fessors Dana and Mareou when, in 1885, I wrote my observa- tions, ‘‘On the Use of the Name Taconic,’ in the introduc- tion to Bulletin 30, of the U. S. Geological Survey. I was satisfied from the evidence presented by Professor Dana, that the limestones of the ‘‘ Lower Taconic” belonged to the Cal- ciferous-Chazy-|!'renton Terrane, and that the overlying schists were properly referred to the Hudson Terrane. The reference of the quartzite beneath the limestone to the Potsdam horizon, also appeared to be consistent with the data known to him. I was but partially convinced, however, from the evidence pre- sented by Dr. Emmons and Professor Marcou that the “ Upper Taconic” slates were stratigraphically pre-Potsdam, or that there was a valid claim for the substitution of the name Taconic for that of Cambrian. Professor Jules Marcou, although a persistent advocate for the use of the name Taconic, did not go to the typical Taconic area to study the “ Taconic System,’ but studied the extension of the “ Upper Taconic” slate and shales in northern Vermont, and identified the “‘ Upper Taconic” as the true “Taconic System.” I have carefully examined the localities where he describes the occurrence of a non-conformity between the Georgia slates and the superjacent so-called Potsdam sandstone and at none of them Dana and others within the past fifteen years on the ground that the writers were putting forth the ‘‘old metamorphic hypothesis” of Mather, Rogers, ete. (See Am. Nat., vol. xxi, pp. 114-320, 1887). C, D. Walcott—The Taconic System of Emmons. 825 could I find a trace of the Potsdam sandstone. The sandstone referred to the Potsdam is of Middle Cambrian age and, at Parker’s farm contains two of the same species of fossils that oceur in the slates conformably subjacent to the sandstone. The only non-conformity found is formed by the overthrust of the Georgia or Cambrian stvata upon the Lower Silurian Ter- rane, just as at Bald Mountain in Washington County, N. Y., Snake Mountain in Vermont and all along the line of the great fault, wherever outcrops of the two systems occur. His extension* of the “Taconic System” to inelude the Potsdam sandstone is in opposition to all of Dr. Emmons’s views of the relations of the Taconic and Potsdam strata, as Dr. Emmons founded the ‘‘ Taconic System” largely on the belief that a great stratigraphic break existed between the Potsdam and Taconic, and that the fauna of the Taconic was unlike that of the “Champlain group,” of which the Potsdam formed the base. Dr. Emmons’s errors are nearly all traceable to his trust in the lithologic characters of the various formations within the Taconic area. He established the “Taconic System” in 1842, on the differences in the lithologic characters of the Taconic rocks and those of the New York ‘ Lower Silurian.’ The un- conformity between the “Taconic System” and “Champlain” series, announced in 184447, was primarily based on the sim- ilarity of the lithologic characters of the Calciferous sandrock of the Lower Silurian and the ealciferous sandrock of what we now know to be, from its contained fossils, a part of his “ Upper Taconic” series. Again, when the latter (calciferous sandrock of the Cambrian) was pushed over on to the dark shales of the ‘Lower Silurian, on the line of the great fault, he identified the latter shales with the “Upper Taconic” shales, and thus obtained an unconformity, as at Bald Mountain, between the Lower Silurian and Taconic strata. He failed to recognize the fact, shown along an outcrop of a hundred miles or more, that the Potsdam and, frequently, the Calciferous Terranes were represented in the geologic sections by a shale undistinguishable from the shale of the Hudson Terrane; also, that the same con- ditions occur in the Champlain valley, in the towns of Fort Ann, Kingsbury, and Hartford, Washington County, N. Y., and that, in several localities, the Trenton limestone is replaced by shale. This explains much of the confusion in his stratigra- phy and, also, in that of Professor Jules Marcou, in northern Vermont, who was misled in the same manner. The shales containing the Primordial fauna are usually lithologically dis- similar from the dark argillaceous shales of the Lower Silurian, * Proc. Bost. Soc. Nat. Hist., vol. vii, p. 371, 381, 1860. 3826 C0. D. Walcott—The Taconic System of Emmons. but, as Dr. Emmons included the dark graptolitic-bearing shales of the Hudson Terrane, within the Taconic area, in the “ Upper Taconic,” he necessarily compared and identified the black shales of the Lower Silurian with the “Black Slate” of the “ Upper Taconic.” He could scarcely do otherwise, when the stratigraphy along the western side of the “Taconic System” supported his theory, if such an identification of the shale was made. The fact that the Potsdam sandstone, as a lithologie forma- tion, is a local deposit in the immediate vicinity of the Adiron- dack mountains and that the sediments being deposited at the other localities at the same time, embedding similar organic remains, were argillaceous, siliceous and calcareous muds, does not seem to have impressed him, although he devotes many pages of his various memoirs to the description and discussion of the lithology of the Taconic and Lower Silurian rocks. Dr. Emmons was not a collector of fossils, or he would have . found them in nearly ail the formations within the Taconic area; and I think that no student conversant with the faunas of the Lower Silurian and Cambrian terranes will long hesitate in concluding that he did not have sufficient critical knowledge of the faunas to which the fossils belonged that he did obtain, to identify the strata from which they came on _ paleontologic evidence otherwise he could not have so confused them.* When Dr. Fitch gave him the fossils that he had found in the “ Black Slate,’ two miles north of Bald Mountain, in 1848, he at once referred them to a pre-Potsdam horizon, on stratigraphic evidence, without making any comparisons with a fauna which he knew to be pre-Potsdam at some other locality. In fact, no such data were at his command at that time, and the reference of the fossils to a pre-Potsdam horizon was based entirely upon the fact that they were in strata which he considered to be situ- ated unconformably beneath the Potsdam sandstone or, in its absence, the Calciferous sandrock. : I wish to mention here that, in 1847, Dr. Emmons did not consider the two species of trilobites as characteristic of the true Taconic slate, but of the overlying ‘‘ Black Slate,’ which he considered to be pre-Potsdam, from the evidence of the Bald Mountain section. I also call attention, again, to the fact that there was no valid stratigraphic evidence of the pre-Pots- dam age of the “ Black Slate ;” moreover, as I have shown, the “Black Slate” is the lowest member of the “Taconic System” and not the highest, as stated by him, in 1847, or next above * Tt is not practicable for me, owing to want of space, to give a full analysis of the paleontologic work done by Dr. Emmons in connection with his argument for the Taconic system. This will appear in my report on the geology of Washington County, N. Y. C. D. Walcott—The Taconic System of Emmons. 327 the “Lower Taconic,” as stated in the scheme of 1856. (See fig. 10.) “The comparisons made by Dr. Emmons between the fossils of the “‘ Black Slate” and the Primordial fauna of Barrande, in 1859, came too late to anticipate the identification of the Prim- ordial fauna in the Cambrian of Sedgwick, for the Cambrian System, as used by me, was correctly identified, paleontolog- ically, by M. Barrande, in 1851.* As I have repeatedly stated, Dr. Emmons assigned the two species of fossils described by him from the “ Upper Taconic” slates to a pre-Potsdam horizon, on stratigraphic evidence that, on investigation, proves to have been based on errors of field ob- servation. Such being the case, there was no proof of the posi- tion of the fauna, as he had no means for comparison with a similar fauna that had been stratigraphically located elsewhere in the geologic series. It wasa fortunate happening that the “ Up- per Taconic” fossils proved to be of pre-Potsdam age, and not a scientific induction based on accurate observations or compari- sons. M. Barrande visited England in 1851 and determined the age of the Primordial fauna found in the typical Cambrian area of Wales before he knew of the existence of the vestige of the Primordial fauna published by Dr. Emmons. Subse- quently, upon the evidence of Dr. Emmons’s published strati- graphic sections, showing that he, Dr. Emmons, knew the fossils to be stratigraphically pre-Potsdam, M. Barrande was misled into crediting him with a discovery (in 1859) that was based on errors of field observation, and I did the same thing in the introduction to Bulletin 80, U. 8. Geological Survey, in 1885. * January 20th, 1851, M. J. Barrande read a paper before the Geological So- ciety of France, upon the ‘‘ Silurian Terrain of England.” He presented a sketch of a section from Wales showing the Archean and, resting upon it, the stages corresponding to the stages C and D, of the Bohemian section, or the strata of the First or Primordial fauna and the Second or Lower Silurian fauna. Above the Lower Silurian the Upper Silurian is shown as resting unconformably upon the latter. In this paper the Lower Cambrian of Sedgwick is identified by organic remains, through comparison—with the established succession of fossils in the Bohemian Basin. (Bull. Soc. Géol. de France, t. viii, pp. 207-212, 1851). [To be continued. | 328 W. J. MeGee—Three Formations of Art. XX VII.— Three Formations of the Middle Adams Slope ; by W. J. McGEez. (Continued Sharm page 143.) THe Appomattox FoRMATION. Character and Distribution.—N ear the summits of the bluffs overlooking the Rappahannock river from the southward a mile or two west of Fredericksburg, a distinctive, stratified, orange- colored sandy clay is found reposing upon Potomac sandstone, from which it is readily distinguishable by its greater homo- geneity, the more complete intermingling of its arenaceous and argillaceous materials, its more regular stratification, and its more uniform and pr edominantly orange color. It is as readily distinguishable from the Columbia deposits, on the other hand, by its vertical homogeneity, its comparatively regular stratifica- tion, its distinctive color, and its greater range of altitude — extending as it does from tide-level to the highest eminences of the Piedmont escarpment between the Rappahannock and the Roanoke. At Fredericksburg the deposit is commonly thin and confined to limited isolated areas, especially at the higher levels, and it appears at but a single locality (Potomac creek) north of the immediate valley of the Rappahannock; but it rapidly increases in thickness and continuity to the southward. About the confluence of the Ni, Po, and Ta rivers it forms the surface over a meridional zone fully 10 miles wide; it is well exposed in the bluffs of the Taponi, along which it reposes upon the fossiliferous Eocene; and in the bluffs of the Mattaponi and the Anna rivers, as well as over the intervening divides, it is the prevalent surface formation, maintaining the characteristics ex- hibited at Fredericksburg save that it is frequently gravelly. In the vicinity of Richmond it is occasionally exposed toward the summits of the river bluffs, but is there less conspicuous than the subjacent Miocene, Kocene and Potomac deposits; while still further southward it continues to thicken and expand. The distinctive orange-colored sands and clays of the forma- tion are typically exposed on and near the Appomattox river from its mouth to some miles west of Petersburg. A mile below Petersburg they are found at tide-level in the river banks ; in the eastern part of the city they appear overlying the fossil- iferous Miocene beds mid-height of the blufis; and at the “ Crater” a mile and a half east, in the railway cuttings in the southwestern part, and on the upland two miles west of the city, they occupy the highest eminences. The zone of out- crop here is at least 30 or 40 miles wide. As at Fredericks- burg, the deposit is a regularly but obscurely stratified orange- the Middle Atlantic Slope. 329 colored clay or sand, sometimes interbedded with gravel or interspersed with pebbles. Perhaps the best exposure is at the “Crater” (a pit formed by the explosion of 8,000 pounds of powder in a mine carried by Federal engineers beneath a Con- federate fort, July 13, 1864). Here the principal material is a dense, tenacious clay, orange, gray, pink, reddish, and mottled in color, plastic yet firm when wet, and so hard and tough when dry that medalions stamped from it as souvenirs are as durable as rock—indeed the well known strategetic measure to which the “Crater” is due was rendered successful by the firmness and tenacity of the clay through which the entire mine was excavated save where it barely touched the subja- cent fossiliferous glauconitic sands of the Miocene. At But- terfield’s bridge in the southwestern part of Petersburg the railway cutting exposes some 20 feet of plastic clay (like that found at the “ Crater’), pebbly and sandy clay, and cross-lami- nated clayey sand, all predominantly orange-colored, in alter- nating beds; and it is noteworthy that here, as at some other points, flakes and lines of white plastic clay similar to those of the Potomac arkose are occasionally included in the formation. The formation continues to thicken and expand south of the Appomattox river, until it forms the surface everywhere in the vicinity of the fall-line save where it is cut away by erosion or concealed beneath the Columbia deposits. Typical: exposures oceur along the Atlantic Coast Line railway at several points, notably on the Roanoke opposite Weldon, N. C., where a few pebbly bands are intercalated within the regularly stratified orange-colored clays and sands. . In brief the inland margin of the Appomattox formation, as exposed north of Roanoke river, is a moderately regularly strati- fied sand or clay with occasional intercalations of fine gravel, generally of pronounced orange hue, and without fossils; it reaches a thickness of probably 50 to 100 feet and forms the predominant surface formation over a zone 40 or 50 miles wide on the Roanoke, but attenuates and narrows northward, finally disappearing at Potomac creek, 4 or 5 miles north of Freder- icksburg ; and although it appears to thicken seaward it soon dis- appears beneath tide level and newer deposits. Stratigraphic Relations.—At Fredericksburg the formation reposes, sometimes ynconformably and again without visible un- conformity, upon the lower member of the Potomac, and like relations are frequently exhibited in the vicinity of Richmond and Petersburg ; in the bluffs of the Taponi generally, and of the Pamunkey two or three miles north of Hanover Court House, it rests unconformably upon fossiliferous Eocene beds ; at the “ Crater” and at a number of other localities in the vicinity of Petersburg it rests without visible unconformity AM. JOUR. Pear SERIES, Von. XXXV, No. 208.—APRIL, 1888. 330 MeGee—Hormations of the Middle Atlantic Slope. upon fossiliferous Miocene beds; in the western part of Peters- burg it lies directly upon the Piedmont crystallines ; two miles northeast of Bellfield it cannot be clearly demarked from the fossiliferous Miocene; and at Weldon it rests. upon deeply ra- vined erystalline rocks save where inconspicuous remnants of Potomac arkose intervene. It therefore reposes upon a founda- tion made up alike of Piedmont crystallines, Potomac deposits, Kocene clays and greensands, and Miocene beds, all of which, with the possible exception of the last, were deeply degraded before its deposition. The formation is overlain only by the alluvium of small streams, eolian sands, etc., on the broad plains between Peters- burg and Weldon, by occasional accumulations of wave-washed debris derived from its own mass in the extensive Quaternary terraces prevailing in its area, and by the characteristic clays, sands, and gravels of the Columbia formation in the vicinity of the larger streams. Taxonomy.—Since the formation has yielded no fossils, its age and relations can only be determined by stratigraphy, de- eree of alteration of materials, depth of erosion, ete. It is mani- festly newer than the fossiliterous Miocene upon which it rests, and older than the Columbia formation by which it is overlain; and its fresh aspect and comparatively slight erosion indicate that its place is much nearer the later than the earlier of these. formations. The Appomattox formation is stratigraphically continuous with an extensive series of clays and sands investigated in North Carolina by Kerr, and referred by him first to the Quater- - nary and subsequently to the Eocene. Since the role played by these deposits 1s increasingly important southward, and since they have been casually recognized at many points in the Southern Atlantic slope, it is probable that they will be found to reach considerable volume in South Carolina, Georgia, and Alabama; and although precise relations have not yet been ascertained, it-is indicated not only by physical considerations but by Fontaine’s recent studies in Virginia and Alabama that at least a part of the Orange Sand of Hilgard and other southern geologists is equivalent to the Appomattox formation of the north rather than the Columbia, which is not known to extend much farther southward than North Carolina. (It should be noted that a part of the deposits designated ‘‘ Orange Sand” by different geologists consist of re-arranged residuary debris of the Tuscaloosa and perhaps other formations.) Too little is yet known of the Appomattox formation to warrant minute interpretation of its history or correlation of its record either with those of other deposits of the Atlantic ‘Slope or with the degradation records of the Piedmont and Appalachian hills. [To be continued. | aT a J. F. Kemp—Diorite Dyke, Orange Co, N. ¥. 3: Go pt Art, XXVIIL—A Diorite Dike at Forest of Dean, Orange County, V. Y.; by J. F. Kemp. RECENT workings in the Forest of Dean magnetite mine, in Orange Co., N. Y., prove it to be intersected diagonally by a dike of diorite. This rock was referred to in the Report of the New Jersey Survey for 1886, p. 107, but not until the last summer was the writer able to take the dimensions under- ground. The dike, about six feet in width, intersects the mine workings in the western branch at an angle of 30°, runs in unbroken width sixty feet across, and disappears in the foot- wall. Microscopic examination of a series of sections along its length proves it to be a very typical diorite quite similar to those described by Hawes* from Compton Falls and by Har- ringtont from the neighborhood of Montreal. The rock is dark gray in color, very fine grained, the component crystals being too small to be distinguished macroscopically. The spec. gravity varies from 2°925 to 2-974. Under the microscope it is found to consist of erystals of plagioclase, hornblende and magnetite, together with certain alteration products of the first two. ‘The hornblende is of the ordinary brown type, generally in well developed crystals show- ing the prism and pinacoidal faces. It is of rather light brown color, not remarkably pleochroice=b>a. The individual crystals vary from 0:17" to 03"™™". In the more altered portions of the dike the hornblende is changed to a greenish mineral resemb- ling chlorite, with threads and fernlike aggregates of secondary magnetite penetrating it. These thread-like aggregates are exceedingly minute, not over 54,™™" in breadth, whereas the original magnetite is in isolated angular masses, seldom show- ing octahedral outlines, ~,-3!;™" in diameter. The magnetite is free from indications of titanium. The plagioclase is in rod- shaped crystals averaging 0-1" by 0°3"™ of irregular outline. Acicular inclusions probably apatite are not infrequent. The extreme smallness of the feldspar crystals made any attempts at separation with-the heavy solutions unsuccessful. Calcite and quartz appear as secondary products, corroborating Rosen- busch’s general statement in regard to the Lamprophyr group of the dike rocks. © Compared with slides of the Campton Falls dike, the feld- spar and magnetite are noticeably more abundant, the horn- blende less so, at the same time the crystals of the last named mineral are less elongated and smaller but much better devel- oped. Compared with the Montreal dike much the same may * This Journal, III, vol. xvii, p. 147. + Geol. Survey Canada, 1877-78, 439. 332 W. LeConte Stevens—New Apparatus for be said, as the latter resembles the Campton rock very strongly in structure. Specimens of each were kindly given me for comparison by Professor Hitchcock and Dr. Harrington. The following analysis by the writer shows higher silica, than the two dikes above referred to, also more alumina and iron, but less lime. Allowing some of the lime to the horn blende, the feldspar appears to be within the oligoclase limits of the plagioclase series. A number of extinctions on 2 Px of from 7°—9° indicated the same. SiOwe ate eS shieaast, RU Bote we 48:19 PASO a eh Ca SLi ARIE ya vin Qe aeiaes eal .7.0 I XG) ait Nie ee Tae ies na ine ag ae Me 18°37 GCA Oi ee LSA AE A see ga ties Wie es Gea 6°85 Mio Ol se Te eer pepe ae pest be 1D TERS Opa eas ge Se he a eee ge men DEE Cee A ON ae Pe Sh eel ORG SL Ps 5°59 boss onGien ition sare se en apie eye 2°31 100°53 Soluble LiCl betore fusions.-25- eee ee Dols Of this: Be: Os ree, Sasi sby) or aind aan © eter area aes 18:0 All the iron determined as sesquioxide. Noticing in the Report on Mining Industry, 10th Census, p. 118, Pl. XXVIII, a trap dike figured as cutting the Palmer Ore Bed near Lake Champlain, I procured specimens of the dike, but on microscopic examination they proved to be dia- base. Stray bowlders of rock similar to the Forest of Dean dike are to be seen not unfrequently in field work in the region, but no other definite locality is as yet known to the writer. Geological Laboratory, Cornell University. Art. XXIX.—Wew Lecture Apparatus for demonstration of Reflection and Refraction; by W. LECONTE STEVENS. THE apparatus of which a brief description is here offered is so simple, and in every particular so much more convenient than any other designed for the samme purpose, that the writer deems it worth bringing to the attention of his fellow-teachers in physics. The refracting medium is a hemi-cylinder of crown glass, carefully polished, and mounted so as to turn on its axis hori- zoutally. The radius is 2°5%, the length 5. The axis passes through the center of a circle of white card-board, whose radius may be 20™ or 80™. Each of its quadrants is graduated from determination of Reflection and Refraction. 333 0° to 90°, as shown in the diagram, the diameter connecting the two zero points being perpendicular to the face of the hemi-cylinder. From a horizontal slit in front of the lantern a beam is sent through the middle of the glass and focussed on the zero-point at the further edge of the card-board, whose “plane has been slightly inclined so that the path of the beam is sharply defined upon it. The incident, reflected, and trans- mitted beams are in the same line, the angle of incidence being zero. The hemi-cylinder is now rotated through any desired angle, for example 50°, as shown in fig. 1. The card-board moves WIND Ny with it. The room should be but slightly darkened, so that there may be no difficulty in reading the graduation on the circle. Part of the beam is reflected and part refracted. Both are plainly seen and the angles of reflection and refraction are measured. Varying the angle of incidence from 0° to 90°, one readily observes that the ratio of the reflected light to the refracted light decidedly increases. ‘Turning still further, the beam from the lantern strikes normally on the curved surface and is totally reflected within the glass at its plane face (fig. 2). Rotating still further, the re-appearance of the refracted beam announces the critical angle, which is read upon the circle. In the common form of apparatus where a beam is deflected by a mirror, then sent through smoky air and cloudy water, - new adjustments are necessary for every variation of the angle of incidence, involving some trouble and loss of time. With the hemi-cylinder but one easy adjustment is needed for all. The higher refractive index of glass is an additional advantage, aside from the superior definition. The expense is scarcely more than that of having the hemi-cylinder made by a practi- cal worker in glass. A small silvered mirror is substituted for the hemi-cylinder if the law of reflection alone is to be exhibited. 334 Scientific Intelligence. SCIENTIFIC INTELLIGENCE. I. CHEMISTRY AND PHYSICS. 1. On the Spectrum of the Residual Glow.—CrooKxeEs has ex- amined the spectrum of the residual phosphorescent glow obtained when the rarer earths are illuminated by the electric spark in a modified form of Becquerel’s phosphoroscope. The glow is ob- served through apertures in a revolving disk, twelve in number, symmetrically placed. On the axis of the disk is a brass cylinder, having twelve teeth at one end. An adjustable spring presses on the teeth, a second spring upon the smooth surface of the cylin- der, these springs completing the battery circuit through the primary of an induction coil. By suitably adjusting the former, the spark may be made to take place at the instant when the substance under exaniination is visible through the aperture in the disk, or to precede it by a very short interval easily calcu- lated. The relative length of the makes and breaks is adjusted by moving the spring to or from the bases of the teeth. Much lower vacua are necessary, since the residual gas has no phospho- rescent spectrum. ‘Che phosphorescent bands in the spectrum of pure yttria do not appear at the same speed of rotation. The first to appear is the greenish-blue band G/, then the deep blue Ga, the citron GO and the deep red Gé; the last at a duration of 0°00175 second. At 0:00125 second God and Gf are equally bright and G7 just visible; and at 000875 second all the bands are seen of their usual brightness. The author has observed that on adding strontia to a mixture of yttria and samaria and on view- ing it in the above phosphoroscope with the wheel rotating rap- idly, the line Go is completely suppressed and the spectrum is identical with that of Marignac’s Ya. Alumina, giving the crim- son line has a very persistant residual glow. Antimony oxide mixed with lime in the proportion of five per cent phosphoresces white with a broad space in the yellow. In the phosphoroscope the glow is green and very strong, the red and orange being ob- literated. Chromium oxide with lime in the same proportion, gives a pale red phosphorescence, the red and orange being cut off in the phosphoroscope. Diamonds glowing pale blue have the longest residual glow, those glowing yellow coming next; those phosphorescing red have no residual glow. Zinc sulphide (Sidot’s hexagonal blende). phosphoresces brilliantly even in a very low vacuum, with a green light. As the exhaustion is increased the edges of the crystals become blue, the two colors finally being equally bright. In the phosphoroscope, however, the blue is visi- ble only at a high speed while the green lasts for an hour or more. The curious fact is noted that the spark spectrum of old yttrium and of the higher and lower fractions obtained from it are per- fectly identical, though the phosphorescent spectra and chemical properties of the three are markedly different; and the author Chemistry and Physics. 335 discusses his sub-molecule theory and his independent element theory in regard to them. On the latter theory the spark spec- trum may belong to Gd.—Proc. Roy. Soc., xlii, 111; J. Chem. Soc., li, 1066 (abstr.) Dec., 1887. G. F. B. 2. On the presence of Chlorine in Oxygen prepared from Potas- sium chlorate.—BELLAMy has observed that all of those substances which when mixed with potassium chlorate facilitate the evolu- tion of oxygen give rise also to the production of chlorine, the greater amount being set free at the commencement of the de- composition. He also calls attention to the fact that all these substances which thus favor the decomposition of the chlorate are acidic in character, and by taking up oxygen form acid oxides or anhydrides ; as for example the oxides of manganese, iron, cobalt and nickel. In some cases the activity is due to admixed acidic bodies, as colecothar, which contains generally basic sulphate. The peroxides give oxygen up and take it again alternately. In the formation, even transitorily, of chromates, permanganates, etc., chlorine or its compounds must be set free and the final residue of the operation must have an alkaline reaction. If, however, the chlorate is mixed with a basic oxide such as lme, magnesia or soda, no evolution of chlorine is observable; but neither is any acceleration of the decomposition of the chlorate produced. The author represents the decomposition in presence of manganese dioxide in three stages. (A) KClO,+MnO,=KMnO,+0+C1. (B) (KMnO,), = K,MnO,+ MnO,+0,. (C) K,MnO,+ MnO, + KC!O,=(KMn0O,), + KC1+ 0.— Ber. Berl. Chem. Ges., xxi, (Ref.) 3, Jan., 1888. G. F. B. 3. On the Interaction of zinc and Sulphuric acid.—Muir and ADIE have studied the interaction which takes place under vari- ous circumstances between zinc and sulphuric acid. Six different grades of zinc were used, and with acids varying in concentration from H,SO, to H,SO, (H,0),,,. About ten grams of zinc and 50° of the dilute acid were used in each experiment. The reac- tions were effected in small flasks each connected by means of a T tube first with a flask containing an ammoniacal solution of silver nitrate and then with another containing a solution of iodic acid mixed with a little starch paste. The experiments in many cases continued for long periods, sometimes three weeks, the flasks being heated when necessary in a zine chloride bath. The results, which are given in tabular form, show the interaction to be one of great complexity. While the action is similar for com- mercial and for approximately pure zinc, the quantities of sul- phur dioxide and hydrogen sulphide diminishing as the zinc be- comes purer, pure hydrogen being almost the sole gaseous pro- duct when the acid is diluted with ten or twelve parts of water even at temperatures near the boiling point; yet it is observed that commercial zine continued to give small quantities of hydro- gen sulphide whatever the strength of the acid and whatever the temperature. When acid of the concentration H,SO,(H,O), acts on commercial zinc at 100° scarcely any sulphur dioxide or hydro- va 336 Scientific Intelligence. gen sulphide is produced; but at 165° abundance of the latter gas is evolved, and torrents of it at 180°, with but little of the sulphur dioxide. Approximately pure zinc interacting with the same acid at 160° gives both gases in abundance. With regard to the appearance of sulphur, the authors are disposed to regard it neither as a product of the interaction of SO, and H,S, nor as produced by the reducing action of the hydrogen upon “the SO, ; but as rather due to the mutual action of hydrogen sulphide and hot concentrated sulphuric acid. In general it appears that the interaction between approximately pure zine and acid is chiefly a direct chemical interaction and that the products of the reactions with the less pure zines. are largely due to the occurrence of secondary electrolytic changes.—J. Chem. Soc., lili, 47-58, Jan., 1888. G. F. B. 4, Orcanic Awnatysis; A Manual of the Descriptive and Analytical Chemistry of certain Carbon Compounds in common usé. By Arspert B. Prescorr, Ph.D., M.D., Director of the Chemical Laboratory of the University of Michigan, ete. 8vo, pp: 533. New York, 1887 (D. Van Nostrand.)—This book ap- pears to be a valuable addition to the literature of technical analysis. For the compounds of which it treats, it furnishes, first a systematic chemical description of these compounds, {ol- lowed by the qualitative and quantitative methods to be pursued in their examination, together with tests for their purity. The titles are arranged alphabetically for convenience of reference. The references given are copious and reliable. Among the articles which seem to us especially valuable are those on the alkaloids, classified as the aconite, the cinchona, the cadaveric, the midriatic, the opium and the strychnos alkaloids; those on elementary analysis, on fats and oils, on coloring matters and on the tannins. Considerable care has evidently been exercised not only in select- ing the titles so as to include substances likely to be offered for examination, but also in giving the results of the latest mvcsti- gations. For clearness, completeness and accuracy, the book will add to the already excellent reputation of its author. It is provided with a full index and is printed and bound in a very satisfactory manner. G. F. B. 5. Practicat Puysics for Schools and the Junior Students of Colleges ; by Batrour Stewart and W. W. HarpaneE GEE. Vol. I. Electricity and Magnetism. 16mo, pp. xviii, 221, London, 1888 (Macmillan & Co.)—This little book, though elementary, is one of the best of its kind in the language. The arrangement is excellent, the experiments well chosen, the descriptions and discussions clear, and the exercises admirably adapted to fix the text in the mind of the student. Morever the apparatus required is simple, much of it being constructed by the pupil himself. We commend the book to those teachers who are engaged in elementary physical laboratory instruction, as admirably suited to their needs. G. F. B. Chenuistry and Physics. 337 6. Spectrum of the oxyhydrogen flame.—Professors G. D. Liverine and J. Dewar find that the spectrum of water extends with diminishing intensity, into the visible region on the one hand and far into the ultra-violet on the other. The latter por- tion they have photographed by means of a single calcite prism, using a long exposure. “The spectrum exhibits the appearance of a series of rhythmical groups more or less overlapping one an- other, and the arrangement of the lines in these groups is shown to follow, in many cases the law that the distances between the lines, as measured, in wave-lengths, are in arithmetical progres- sion.” Their researches apparently confirm the theoretical con,,, clusions of Dr. Griinwald of Prague, for they discovered a num- ber of lines which apparently occupy the positions which they should according to his hypothesis.—Royal Society, Feb. 2; Nature, Feb. 16, 1888, p. 383. a) 0 7. Application of the Electrolysis of Copper to the Measure- ment of Electric Currenis.—In the process of standardizing Sir William Thomson’s new electrical instruments, Mr. Gray has been led to examine the accuracy of the method by means of the deposition of copper, and concludes that the constant of an elec- tric current instrument can be obtained with certainty, by this method, to one-twentieth of one per cent.— Phil. Mag., March, 1888, p. 179. ap a 8. Influence of light upon electrical discharges.—Hertz in a previous number of the Annalen der Physik having called atten- tion to a remarkable influence of the ultra-violet rays upon elec- trical discharges, E. Wiedemann and H. Ebert repeated his re- searches and have confirmed his results. When a spark will no longer pass between the terminals of a Ruhmkorff coil, if a beam of ultra-violet light falls upon the electrodes the spark will traverse the interval between the electrodes. Wiedemann and Ebert show that the effect is also produced by the light of burn- ing magnesium and that the effect is confined to the ultra-violet rays; red and green producing no effect. The effect is produced at the negative electrode and not at the positive. The authors studied the effect in various gases, and at different pressures. The phenomenon varied with the pressure and with the medium. ‘The same number of the Annalen contains a paper by W. Hall-° wachs on the influence of light upon electrostatically charged bodies. He finds that the ultra-violet rays modify the charge and the insulating properties of bodies.—Annalen der Physik und Chemie, No. 2, 1888, pp. 241-264, 301-312. J. T. 9. Wave-lengths of standard lines.—In a long paper continued ~ through two numbers of the Annalen der Physik, F. Kurtpaum discusses the various methods of measurement of wave-length, and gives the results of the most refined methods which his experience has led him to adopt. His measures of the wave-length of one of the components of the sodium line, D,, compare as follows with those of previous observers : 338 Scientific Intelligence. D,=589, 625, Miiller, Kempf. 607, ) ; 603, i Bell. . 602, Peirce. 589, 590, Kurlbaum. —Annalen der Physik und Chemie, No. 2,1888, pp. 381-412. Tals Il. Grotocy AND NatuRAL History. ~ 1. On the distribution of strain in the Earth's crust resulting Jrom secular cooling, with special reference to the growth of con- tinents and the formation of mountain chains ; by CHARLES Davison. With a Note by G. H. Darwin. —Starting from the results reached by Sir W. Thomson and independently by Prof. Darwin in regard to the rigidity of the earth, and from the con- clusions of the former as to the secular cooling of the earth, Mr. Davison has gone forward and discussed the distribution of strain in a solid globe resulting from secular cooling with reference to the effect of this distribution on the great features of the earth’s surface. His conclusions, as will be seen, throw much light upon | what he terms “the beautiful contraction- ‘theory of mountain evo- lution ” to which the work of Thomson and Darwin leads up. The author starts by supposing that the earth is bounded by a smooth, spherical surface and is made up of a great number of very thin concentric shells, each so thin that the loss of heat may be considered throuchout as uniform. The first conclusions reached are: 1, “That the rate at hich any shell parts with its heat increases to a certain depth below the earth’s surface, where it is a maximum, after which it decreases toward the center, and the depth of the surface of greatest rate of cooling is continually increasing, and varies as the square root of the time that has elapsed since the consolidation of the globe.” Also, 2. “Folding by lateral pressure takes place only to a certain depth below the earth’s surface; at this depth it vanishes, and, passing through it downwards, folding gives place to paseo by lateral tension.’ Accepting now, for the sake of simplicity, 174,240,000 years as the time that has elapsed since the consolidation of the earth, a period which lies well between the limits set by Sir W. Thomson and for which the depth at which the rate of cooling becomes practically insensible is 400 miles, the following conclusions are See 3. “(1) Folding by lateral pressure changes to stretching by lateral tension at a depth of about five miles. (2) Stretching by lateral tension, inappreciable below a depth of about 400 miles, increases from that depth toward the surface; it is greatest at a depth of 72 miles, that is, just below the surface of greatest rate of cooling; after this, it decreases, and vanishes at a depth of Geology and Natural History. 339 about five miles. (3) Folding by lateral pressure commences at a depth of about five miles, and gradually increases, being greatest near the surface of the earth. ” Furthermore, 4, “Within certain limits, it is true that the depth of the unstrained surface increases as the square root of the time that has elapsed since the consolidation of the globe.” Also, 5. “ Folding by lateral pressure was effected most rapidly in the early epochs of the earth’s history, and, since then, the total amount of rock folded in any given time decreases nearly in pro- portion as the square root of the time increases. The same law being approximately true of the total amount of rock stretched by lateral tension, it follows that the ratio of the amount of rock stretched to the amount folded in a given time is very nearly | constant, but in reality slightly diminishing as the time increases.” While not claiming that great weight should be attached to the numerical results obtained, the author goes on to consider the effects of crust-stretching and folding on the evolution of the earth’s surface features. Assuming that the formation of the great continental masses took place in the initial period of the earth’s history, it follows that: 6. “Owing to the pressure of the continental wrinkles, the amount of stretching under them must have been very much less than under the great oceanic areas. Thenceforward, therefore, crust-stretching by lateral tension must have taken place chiefly beneath the ocean-basins, deepening them and intensifying their character. And, in leading to the continual subsidence of the ocean-bed, it is evidently a physical cause of the general perma- nence of oceanic areas; a cause, it is true, continually receding from the surface, and diminishing in intensity with the increase of time, but probably even now not quite ineffective. ae Again, the amount of crust-stretching by lateral tension being greatly in excess of the amount of crust: folding by lateral pres- sure due to secular cooling, it follows that folding beneath the ocean-bed will do little but diminish its rate of subsidence. The effects of folding in changing the form of the earth’s surface features will therefore be most apparent in the continental areas, especially in those regions where the change of vertical pressure above the folded layers diminishes most rapidly, ¢.¢., near the coast-lines where the slope toward the ocean depths is ereatest. It is perhaps worthy of remark that these are the distriets where earthquake and voleanic action are now most prevalent. In the coast regions, moreover, the products of continental denudation are chiefly deposited, and the rock-folding due simply to secular cooling produces in vast masses of sediment. still more crushing and folding. The direction of the folds will be perpendicular to the average slope of the surface above them, 7.e., they will gen- erally be parallel to the coast-line. Hence the continents will grow by the formation of mountain chains along their borders. “Jn a given time, the amount of rock-folding resulting from secular cooling was greatest in the first epochs of the earth’s his- 340 Scientific Intelligence. tory, and diminished as the time increased. It does not neces- sarily follow that the early mountain ranges were the loftiest and most massive, but probably they were; and very possibly also, the displacement, by crushing and folding, of two neighboring portions of rock was greatest in early times. But, taking into consideration the whole surface of the globe, the process of mountain-making diminishes with the increase of the time, and so also does the rate of continental evolution. “It cannot be said that the contraction theory on the hypothesis of solidity is entirely free from objections. ‘Two very obvious ones have already been alluded to in the course of this paper, namely (1) The small calculated depth of the unstrained surface, especially in early geological periods; and (2) The small propor- tion of folded rock to stretched rock directly produced by secular cooling. But I do not think that these objections are by any means fatal to the theory. Assuming the earth to be practically solid, and to have been originally at a high temperature through- out, I believe it may be concluded that the peculiar distribution of strain in the earth’s crust resulting from its secular cooling has contributed to the permanence of ocean-basins, and has been the main cause of the growth of continents and the formation of moun- tain chains.” In the course of his discussion the author takes up the argu- ment of the Rey. O. Fisher on the insufficiency of the contraction theory, and gives several reasons why it should be regarded as inconclusive. The subject discussed by Mr. Davison is further considered by Prof. Darwin in a note appended to the paper of the former; he shows that some of the conclusions may be reached somewhat more simply, and furthermore makes some deductions as . to the results of distortion and the magnitude of the effects accom- plished. Prof. Darwin calls attention to the fact that the stretch- ing of the earth’s crust which is of importance from a geological point of view is the excess of the actual stretching above that due to rise of temperature—this if negative is a contraction and is shown by a erumpling of strata. Assuming the time elapsed since consolidation to be 100 million years, the present depth of the stratum of no strain is two miles, and the depth is proportional to the time since consolidation. For the upper layers of the earth it is found that the integral effect is always a stretching, and this is negative; that is, it is a crumpling, as was to be expected. As to the amount of the crumpling, it is found that in ten million years 228,000 square miles of rock will be crumpled up and piled on the top of subja- cent rocks. Prof. Darwin concludes : 7. “The numerical data with which we have to deal are all of them subject to wide limits of uncertainty, but the result just found, although rather small in amount, is such as to appear of the same order of magnitude as the crumpling observed geologi- eally. “The stretching and probable fracture of the strata at some 4 Geology and Natural History. 341 miles below the surface will have allowed the injection of the lower rocks amongst the upper ones, and the phenomena which we should expect to find according to Mr. Davison’s theory are eminently in accordance with observation. It therefore appears to me that his view has a strong claim to acceptance.” 2. Lavas of Krakatoa.—Prof. Judd reviews the analyses of these lavas (Geol. Mag., vol. i, 1888), and shows that they are es- sentially andesyte, in which enstatite predominates over the py- roxene, and that much glass is present. Yet they vary greatly in the proportions of the constituent minerals and hence widely in ultimate composition. There is a large difference also in the condition of the glassy base as to its microlites, their number, grouping, and other peculiarities. A fragment of the obsidian, on approaching a white heat, swells up as it melts into a cauli- - flower-like mass five or six times the size of the original, proving the presence of some volatile material which is given off at a high temperature. The amount of distension undergone was found to be 33 to 7, 8 or even 9 times that of the glass. The ob- sidian sometimes contains knots of pitchstone, the feldspar crys- tals of which show the effects of a large amount of corrosion, and sometimes of re-solution. Dr. Judd observes also that the stony lavas sometimes have the feldspar, pyroxenes and magne- tite aggregated in little knots, producing a kind of structure which he calls glomero-porphyritic. 3. Geologie von Bayern, von Dr. K. WiLHELM von GUMBEL. First Part, Elements of Geology. Lieferung 5, in continuation of volume I, pp. 961 to 1088 8vo, with numerous illustrations.— Although entitled Geology of Bavaria, this work by Dr. von Gumbel so far as published is essentially a comprehensive treatise on the science. The sheets here issued treat of the Pliocene, Quaternary, and Recent periods, and then commences, on p. 1020, a new division of the work, on Geogeny or the development of the Earth. 4. Recent contributions to our knowledge of the vegetable cell. Die Morphologie und Physiologie der Pflanzenzelle, von Dr. A. Zimmermann. 8vo, 223 pp. (From Schenk’s Handbuch der Botanik.) Die morphologische und chemische Zusammensetzung des Protoplasmas, von Dr. F. Schwarz. 1887. 8vo, 244 pp. (In Cohn’s Beitrige zur Biologie der Pflanzen. Bd. V.) Articles in current Journals, cited in the text. The progress which modern methods of research have permitted Vegetable Physiology to make is shown by even a superficial comparison of the classical treatises of Mohl (1851) and Hof- meister (1867) with any of the recent publications on the same subject, for example, with that placed at the head of the list given above. It will be remembered that Mohl described pro- toplasm and first gave it its name in 1846, and therefore, at the time of the publication of his ‘“‘ Vegetable Cell,” his attention was directed largely to the examination of the cell-contents; whereas, up to that time, a great part of the study in this field had been 342 Scientific Intelligence. devoted to the forms, markings and distribution of the structural elements. In Hofmeister’s voluminous work, protoplasm and the other cell-contents receive the larger share of space, and are treated of as fully as the limitations of the methods then in use allowed. By the application of improved processes of staining the con- tents of cells, and especially.by the employment of the newer ob- jectives, recent investigators have been encouraged to attack problems which it would have been thought hopeless even to approach twenty years ago. It is neediess to dwell upon the fact that many of these problems have not yet been satisfactorily solved, and that not a few of them are still unanswered. The present sketch will allude to a few of the contributions published during the last vear or two, and an attempt will be made to indicate some of the relations to what has been previ- ously known. In extended studies by Reinke and Rodewald (1881) on the chemical character of protoplasm, it was stated that the reaction is alkaline. By careful microchemical studies of cell-contents, Schwarz (1887) has ascertained by the use of an infusion of red- cabbage that the reaction of ceil-sap is sometimes acid and some- times alkaline, but that of the protoplasmic mass is always alka- line. This alkalinity he ascribes to the presence of potassium compounds, presumably proteid combinations. The acid reaction detected in the case of old cells when all the contents are placed in contact with test paper is due to the considerable excess of acid cell-sap. Schwarz has extended his studies to certain points regarding the structure and chemical constitution of protoplasmic contents of the cell. Recent writers have distinguished more or less com- pletely and with considerable diversity of nomenclature, between the general protoplasmic mass of the vegetable cell and its differ- entiated protoplasmic contents. The latter, which are always imbedded in the former, are known as the nucleus and the chro- matophores: the mass in which they are held is termed the cyto- plasm. The chromatophores are three, namely, starch-accumu- lators, color-granules, and chlorophyll-granules. It is with the characters of the cytoplasm, nucleus and chlorophyll-granules that Schwarz has been specially engaged.. Concerning 1 the for- mer, he says that in Cytoplasm there exists no normal “network, but that a part of the mass can under certain circumstances be- come transformed into threads and constitute the well-known fi- brill. Cytoplasm is to be regarded as a mixture in which under certain conditions there can be a separation of its solid, viscid and fluid substances. The microsomata (the very minute gran- ules which occur in the cytoplasm) are sometimes of the nature of precipitates. In the nucleus, Schwarz discriminates between (1) a fibrillar framework, (2) a basic substance, (3) nucleoli, and (4) an envelop- ing membrane. The chemical constituent of the framework is Geology and Natural Listory. 343 termed by him linin; that of the basic substance, paralinin; that of the nucleoli, pyrenin; that of the peripheral envelope, amphi- pyrenin:. while in the fibrillar framework is distributed chroma- tin. The chlorophyll granule is believed by him to possess nu- merous fibrille imbedded in a basic substance and surrounded by a plasma-membrane, but the fibrillar character is detected only when the granules are swollen by immersion in water, and a portion of the basic substance is dissolved. Schwarz distin- guishes two proteids in the above, chloroplastin and metaxin. The author’s earlier studies under Pfeffer naturally led him to ex- periment upon the subject of precipitation-membranes and the allied one of vacuolation. He holds that when there is a mix- ture of two substances, one of which is soluble and the other insoluble but capable of limited enlargement by imbibition, there can be vacuolation; but in a mass of homogeneous substance there can be no vacuolation. The author has conducted many in- teresting experiments relative to the behavior of the different proteids with regard to digestive ferments, and also with regard to the action of various metallic compounds. EK. Belzung (Ann. Se. nat. bot. iv, 179, 1887) has criticised Schimper’s views relative to the formation of starch-grains through the agency of the starch-accumulators (leucoplasts). He states that in many instances the bodies described by Schimper could not be found, and that in many of the cases where they were seen they did not bear out Schimper’s theory. In a rejoinder (ibid. VI, v, p. 77) Schimper demonstrates defects in Belzung’s observa- tions and shows that he has no reason to modify his original con- clusions. Heinricher (Mitth. bot. Inst. zu Graz, 1) has pointed out the occurrence in the tissues of certain Cruciferee of idioblasts which he terms albuminoid-sacs. .They are best seen in sections par- allel to the plane of the leaf, in alcoholic material treated with Millon’s reagent or in material which has been acted on by boil- ing water. The sacs or vesicles are more or less curved and are generally simple. It has been known from researches by Hanstein and DeVries that when certain fresh-water Algz are placed in,a nutrient plas- molytic solution, for instance, a ten per cent solution of glucose or a twenty per cent solution of cane-sugar, the shrunken proto- plasmic mass still remains living and even manifests some phe- nomena of growth, At this point Klebs (Ber. deutschen bot. Gesellsch., 1887, p. 189) takes up the subject, showing that it is possible to examine in this manner the mode of growth of the cell-wall. He concludes from his observations that in the case of Vaucheria the growth is by apposition in the newer walls and by stretching in the enlargement of the older walls. He examined also the relations of growth under these conditions to the sur- roundings, but of these results he has given only a general out- line. The following statement relative to the nucleus is of con- siderable interest. From experiments on the cells of Zygnema and + 344 Miscellaneous Intelligence. of Funaria, in which the protoplasm was by means of plasmolysis severed into parts, 1t was only the segment which retained the nucleus which was capable of completely restoring the.cell: the other fraction remains living for weeks, but although such seg- ments of Zygnema form no new cell-wall and do not grow in length, they are nevertheless assimilative and accumulate much starch. He states that the physiological réle of the nucleus is as yet wholly unknown. It is well to note that in cultures like those detailed by Klebs it is advantageous to add to the liquid one- tenth of one per cent -of potassium chromate in order to prevent the appearance of destructive fungi in the nutrient solution. Janse of Leyden has published interesting studies made at the Zoological Station at Naples, in much the same field, the dif- ference being chiefly that he employed salt-water alez. (Botan. Centralbl., xxxil, p. 21.) Haberlandt (Ber. deutsch. botan. Gesellsch., v, 205) has exam- ined the position of the nucleus in certain vegetable cells, and concludes that in most cells whose walls show a localized thick- ening or an increase of surface, the nucleus is in close proximity . to the active portion. He finds further, that from any given wood-parenchyma cell only one thylle developes, and this on the side where the nucleus lies and where a duct.is in contact: the nucleus is transferred to the thylle. The author has also studied to some extent the behavior of the nucleus in severed threads of Vaucheria. His observations, made independently of those of Klebs, have led him to about the same conclusions. Zacharias (Botan. Centralbl., xxxii, 59) has re-examined th relations of the nucleus to its surrounding protoplasm, and finds that the latter does not enter the nucleus when division is taking place, but that there is always a distinct demarcation between the two. 4 Zopf has detected in the spores (conidia) of Podosphera oxy-— acanthe, granules hitherto undescribed. For them he proposes the name of Fibrosin-granules, and states that they probably con- stitute a portion of the reserve matters. G. L. G III. MisceELLANEOUS SCIENTIFIC INTELLIGENCE. 1. Beitrdge zur Geophysik: Abhandlungen aus dem geograph- ischen Seminar der Universitdét Strassburg, herausgegeben von Prof. Dr. Grore GERLAND. 1 Band. 373 pp., 8vo. Stuttgart, 1887. (EH. Schweizerbart’sche Verlagshandlung, E. Koch.)—This volume forms the first of a series to be published at intervals, perhaps yearly, as the material accumulates. It contains papers by the members of the geographical Seminar of the Strassburg University, and speaks well for the activity of a teacher who can inspire his pupils to accomplish such results. The introduction by the editor is an interesting and comprehensive discussion of the scientific scope of Geography, its various departments, and its relation to the kindred sciences of geology, anthropology, ete. Miscellaneous Intelligence. 345 The memoirs forming the bulk of the volume are four in number. The first by H. Blink is on the winds and sea currents in the region of the small Sunda islands; a second by H. Hergesell on the change in the planes of equilibriam of the earth caused by the formation of the polar ice masses and the resulting changes in sea level; a third by the same author on the influence which a change in the geoid can have upon the relative heights of a plateau and on the fall in a stream bed; a fourth by E. Rudolph discusses submarine earthquakes and eruptions, as to their phenomena, dis- tribution and cause, with a catalogue of observed occurrences of ee kind. Klima und Gestaltung der Errdoberfliche in threr Wech- Che dargestellt von Dr. J. Propst. 173 pp. 8vo. Stutt- gart, 1887, (E. Schweizerbart’sche Verlagshandlung, EK. Koch.)— The author’s discussion of this subject falls into two parts. The first embraces the consideration of the climatic conditions of the successive geological periods, and the second takes up the modi- fications and mutual relations between.the climatic development and the form of the earth’s surface, The peculiar features of the climate of the early geological periods are discussed with their causes, and a close similarity traced between this and the true ocean climate of the present day in its greater uniformity, greater warmth and peculiar distribution. The consideration of the later periods follows with an attempt at an explanation of their climatic conditions. This portion of the work offers a number of points of interest with less that admits of criticism than the following part. It is hardly possible to accept the author’s estimate of the effects upon the fundamental development of the earth’s features of the contraction caused by the unequal cooling of portions of the underlying earth’s crust by the cold currents which form part of the sea’s circulation. 3. Beobachtungs-Ergebnisse der Norwegischen Polarstation Bossekop in Alten von. Axset 8. Steen. I Theil, Historische Hinleitung, Astronomie, Meteorologie, 100 pp. with 4 plates, Christiana, 1887. (Die Internationale Polarforschung 1882-83). —This volume is one of numerous contributions made to science as the result of the labors at the International Polar Stations established in 1882. The Norwegian station was at Bossekop at the end of the Altenfjord, 69° 28’ N. lat. and 23° 15’ E. long. The observations made extend over the subjects of astronomy and meteorology and are given in full detail in a series of tables; the daily cause of the air-pressure, temperature, moisture, wind veloc- ity, and cloudiness are given on the closing plates. 4, The Asteroids, or Minor Planets between Mars and Jupiter ; by Daniet Kirxwoop. Lippincott & Co., Philad. 1888. 12°, pp. 60.—A very convenient summary of facts and a collection of tables of the small planets. These are followed by a discussion of the various facts shown by the tables. 5. A Manual of Descriptive Geometry ; by C. A. Waxpo. Heath & Co., Boston. 8°, pp. 77.—A book of suggestions, defi- 20a 346 Miscellaneous Intelligence. nitions, problems, etc., whose scope is by no means to be measured by the number of pages. 6. Annals of the Astronomical Observatory of Harvard Col- lege; Vol. XIII, p. ti. Cambridge, 1888. E. C. Pickurine, Director. The zone observations made, principally by Professor Searle, in the years 1882-6 with the transit wedge photometer attached to the large equatorial are here published. The stars measured are largely from the zones observed by Bond. 7. The Movements of the Earth; by J. Norman Locxyzr. Macmillan & Co. 1887, 8°, pp. 130.—A small volume, the first of a series promised by Mr. Lockyer, to give the Outlines of Physiography. This volume explains the various motions of the earth, and the first principles of the measurement of space and time in Astronomy. 8. Publications of the Lick Observatory of the University of California ; E.S. Hotpen, Director. Vol. I. Sacramento, 1887. —This volume contains a history of the institution, an account of various observations made during the progress of construction; a description of part of the instrumental equipment; and a series of reduction tables. 9. Cordoba Observations.—The ninth volume of the Resultados del Observatorio Nacional Argentine, containing the observations made under Dr. Gould’s direction in 1876 has been received. 10. Elementary Treatise on Analytical Mechanics; by W. G. Peck. 319 Qp.,8vo. New York and Chicago, 1887 (A. 3. Barnes & Co.).~—-The important principles of analytical mechanics are presented in this volume systematically and with a good deal of clearness of arrangement though without much claim to origin- ality. OBITUARY. James C. Boots died March 21, at Philadelphia, at. the age of seventy-eight. He was the author, with M. H. Boyé, of the Encyclopedia of Chemistry, published in 1844, and also of a report on the Geology of Delaware, with chemical notes. He contributed a considerable number of papers on chemical subjects, several of them in analytical mineralogy. He was for many years on the staff of the U. 8. Mint at Philadelphia. Geologie des Miinsterthals, von Dr. A. Schmidt, A.O., Prof. Univ. Heidelberg. 2d part. Porphyry. 172 pp. 8vo. Heidelberg, 1887 (Carl Winter’s Universitats- buchhandlung). Uebersich der Physiko-geographischen verhaltnisse des Huropaischen Russ- land, wahrend der verflossenen geologischen Perioden von A. Karpinski. 44 pp. 8vo, with one plate. St. Petersburgh, 1887. FS ay 22 A. E. FUOTE, M. D., (j i) No. 1223 BELMONT AVENUE, Rero kite, M agnet Cove-Ark. “5 PHILADELPHIA, PA. aa @ AEF. Twin Crystal Zircon. Copies of Naturalist’s Leisure Hour, 32 pages, given free on applica- tion. If stamp is en- closed, the subscriber’s edition, on heavy paper, Please state in what Department of Science you are specially in- terested. is sent. Largest Stock of Scientific Books in America. Largest Stock of Minerals inthe World. i Smoky Quartz, | ia pe | 5 Rutile, FE FOOTE: Magnet Cove,Ark. (COANE TH: Noss Page Art, XXIL.—The Absolute Wave-length of Light; by L. | BEbU oo 0. Se ed ee rr XXIIL—History of the changes in the Mt. Loa Craters; by : J). Dana (With: Plates V and2\)) 2-52 5 eee 282 - XXIV.—The Electromotive Force of Magnetization; by HL: Nicwots and WS: Rankin 2 32 ea eee 290. XX V.—Notes on certain rare Copper Minerals from Utah ; ~ by W. F. Hittepranp and H. 8. Wasnineton --__-_--= 298 XXVI.—The Taconic System of Emmons, and the use of the name Taconic in Geologic nomericlature; by C. D. Wancorr,:..( Wath Plate): 22 ee 307 eee XXVII.—Three Formations of the Middle Atlantic Slope; es by, WJ. MecGune eee ee 328 a XX VIII.—Diorite Dike at Forest of Dean, Orange County, if Ne YS by. J. oh ARRM PAS ae ee oe 331 | XXIX.—New Lecture Apparatus for determination of Re- flection and Refraction; by W. L. StrvENs ___.._--: 332 SCIENTIFIC INTELLIGENCE. Chemistry and Physics—Spectrum of the Residual Glow, eee 334.—Pres- ence of Chlorine in Oxygen prepared from Potassium chlorate, BELLAMY: Interaction of zine and sulphuric acid, Murr and Abin, 335,—Organie Analysis, A. B. Prescort: Practical Physics, B. Stewarr and W. W. H. Gux, 336.—- Spectrum of the oxyhydrogen flame, G. D. Liveine and J. DEwaR: Application of the Electrolysis of Copper to the Measurement of Hlectric Currents, GRAY: Influence of light upon electrical discharges: Wave-lengths of standard lines, | BF. KURLBAUM, 337. Geology and Natural History.—Distribution of strain-in the Earth’s crust Toca from secular cooling, C. Davison and G. H. DARWIN, 338.—Layas of Krakatoa: Geologie von Bayern, K. W. von GUMBEL : Recent contributions to our knowl- edge of the vegetable cell, 341. Miscellaneous Scientific Intelligence.—Beitrage zur Geophysik, G. GERLAND, 344. Klima und Gestaltung der Hrdoberflache in ihrer Wechselwirkung dargestellt von J. Progst: Beobachtungs-Ergebnisse der Norwegischen Polarstation Bossekop in Alten, A. S. Steen: The Asteroids, or Minor Planets between Mars and Jupiter, D. Krrkwoop: Manual of Descriptive Geometry, C. A. (ff Watpo, 345.—Annals of the Astronomical Observatory of Harvard College, H. | C. PICKERING: Movements of the EKarth, J. N. Lockyer: Publications of the Lick Observatory of the University of California, E. S. Hon~pen: Cordoba Observations: Elementary Treatise on Analytical Mechanics, W. G. PEOK, 346. Obituary.— JAMES C. Booru, 346. Chas. D. Walcott, U. S. Geological Survey. WN No. 209. Vou. XXXV. | — MAY5, 1888. ~ Established by BENJAMIN SILLIMAN in 1818. ae. Man Te THE JOURNAL OF SCIENCE EDITORS JAMES D. ann EDWARD S. DANA. oe < . hot ASSOCIATE EDITORS Proressors JOSIAH P. COOKE, GEORGE L. GOODALE anpD JOHN TROWBRIDGE, or Camsripex, Prorzssors H. A. NEWTON anv A. E, VERRILL, or New Haven, Prorresson GEORGE F. BARKER, or PHILADELPHIA. THIRD SERIES, VOL. XXXV.—[WHOLE NUMBER, CXXXV.] No. 209—MAY, 1888. WITH PLATES VI, VII. NEW HAVEN, CONN.: J. D. & E. S. DANA. 1888. TUTTLE, MOREHOUSE & TAYLOR, PRINTERS, 371 STATE STREET. ] | j | | | LPF TESS TLL EDEL AG DE NTE IED TT LG STEELE IO EE DTS TL LE EERE SE ETT EPR LOD COREE Published monthly. ‘Six dollars per year (postage prepaid). $6.40 to foreign sub- seribers of countries in the Postal Union. Remittances should be made either by money orders, registered letters, or bank checks, GHORGEH- TL ENGLISH: & CO; DEALERS IN MINERALS. Send for Catalogue. Free to any Address. Recent Additions to our Stock: Remarkably Modified Quartzes from North Carolina; Very choice Rutiles from North Carolina; Apophyllites, Magnetites, Calcites, Pyrites, etc., from French Creek ; Dioptase, Alexandrites, Ouvarovites, Urals; Blendes, Magnetites, etc., from Binnenthal ; Augites (very fine) from Sweden; Enstatites (large) from Norway ; Many other rare and fine minerals, College orders especially solicited and satisfaction guaranteed. Pure minerals for Blowpipe Analysis, a specialty. SPECIAL:—We offer for sale (entire) the collection of one of our most prominent mineralogists. It contains over 4000 specimens, including many large and exceedingly grand specimens. It is widely known as one of the finest private collections in America. Price, $8000. An exceptional opportunity for a College. GEO. L. ENGLISH & CO., Dealers in Minerals, 1512 Chestnut Street, - - Philadelphia, Pa. THE AMERICAN JOURNAL OF SCIENCE [THIRD SERIES. Arr. XXX.—The Absolute Wave-length of Light ; by Louis Ioiaiging Jeevan JOE [Continued from page 282.] THIS continuation of my previous paper contains the angular measurements and the details of the measurement and calibration of the gratings, together with the final results. In addition I have endeavored to point out the probable sources of error in some recent determinations of absolute wave-length. Angular Measurements. In my former paper (this Journal, March, 1887) the work with glass gratings was described in ‘detail, so that it will only be necessary to summarize it here. Grating I was used during October and November, 1886, and forty-eight series of observations were obtained as follows, each series consisting of three to seven observations. Date. Number of series. Angle. Octeh9: 1 Alpi Asie? 20, 1 45 1 48 -4 22, 2 45 1 48 2 23, 1 45 1 49 °8 26, 4 45 1 49 +3 27, 3 45 1 48 *2 31, 1 45 1 50:1 Am. Jour. Sci.—THIRD SeRIES.— VoL. XX XV, No. 209.—May, 1888 21 348 L. Bell—Absolute Wave-length of Light. Date. Number of series. Angle. Nov. 3, 1 45° 1! 487°6 4, 3 45 1 47 °4 5, 2 45 1 47 °9 10, 4 45 1 47 °8 11, 6 45 1 49 °7 16, 8 45 1 48 °2 Wee i) 45 1-47 +5 20, 6 Ab 1 gaie-5 Grating I was used at an average temperature of very nearly 20°, to which all observations were reduced. The average barometric height was 761™™, so that no correction was required for this cause. Weighting and combining the above observa- tions the final value is @ 45° 1’ 48244 011, corresponding to the spectrum of the third order. The resulting probable error in wave-length is about one part in a million. Grating II was used in March, 1887, at an average temper a- ture of very nearly 20° and an average pressure of 760". Thirty-six series of observations were obtained in the fourth order, as follows: Date. Number of series. Angle. Mar. 6, 2 AD ONS yy alla 10, 1 42 4 58 ‘6 Wis a 42 5 lea 15, 1 42 5 4:0 16, 6 42 4 57 °8 ie 6 42 4 58 °5 18, 7 42 4 59 +1 23 6 42 4 58 °3 Combining and weighting, the mean value is: p = 42° 4' 5928 + 0"-2, The probable error is equivalent to about one part in six hun- dred thousand in the wave-length. Both the glass gratings were used exclusively for the line D,, which was on the whole most convenient for measurement, D, being rejected by reason of the troublesome atmospheric lines. The relative wave-lengths of a very large number of lines have been so exactly determined by Prof. Rowland that any one of them would have given results equally valuable, and in the subsequent work with gratings III and LV, two of these standard lines were employed. In this sagan part of the investigation, the gratings as before LI. Bell—Absolute Wave-length of Light. B49 mentioned were used on the large spectrometer in which the telescopes. were kept at a fixed angle and the grating was turned. This method is, of course, applicable only to very solid instru- ments in which the angle can readily be kept constant, and it should be further noted that it also requires the use of very pertect gratings, since the grating is used asymmetrically. As a result of this the spectra on the two sides differ in dispersion, and if the ruling is irregular either in spacing or in contour of the individual lines, may differ quite widely in focal length, definition and illumination. After critical examination gra- tings III and IV appeared to be so nearly perfect in ruling, as to be quite secure from the dangers of the method. The method has moreover the distinct advantage of enabling the angle of deviation to be varied within certain narrow limits. Hence it becomes possible so to arrange the apparatus as to give to some convenient line a double reflection that shall be an exact sub- multiple of 360°. This once accomplished it becomes an easy matter completely to eliminate the errors of the divided circle and obtain a value of ng, dependent only on the micrometer constants, which in turn may be themselves almost eliminated. To be sure, this method practically confined observations to the spectra of a given order and limits the choice of lines for meas- urement, but the first objection does not apply to gratings of which the ruling is very nearly perfect, and since the relative wave-lengths of a large number of lines are known with very great exactness, measurements of the absolute wave-length are quite comparable even if made on different lines. As regards the constancy of the angle between the collimator and observing telescope there was every reason to expect entire permanence throughout the experiments, and observation soon justified this expectation. The telescopes were firmly secured at both ends to one and the same casting, which in turn was firmly bedded in a brick pier. In addition the size of the appa- ratus was such that a variation of even 1” in the angle was quite improbable. The angle measured in the ordinary way with a collimating eye-piece could be determined to 1” of are, exclu- sive of errors of graduation in the circle. At first there ap- peared to be distinct variations in the angle as determined at the beginning of each series of observations, reaching some- times more than 10”. It soon appeared however that when the same part of the circle was used the angle between the tele- scope was sensibly the same and the apparent variations were then traced to a periodic error in the divided circle, which by the method of repetition was completely eliminated from the measurements of angles of deviation and only appeared in the determinations of @. This error was finally eliminated by meas- uring @ in various portions of the circle. 350 L. Bell—Absolute Wave-length of Light. The method of determining g was as follows: The instru- ment being adjusted by the ordinary methods, a suitable line was selected for measurement and then the angle @ was slightly increased or diminished until by measurement of a double de- flection ng was found to be very close indeed to 360°. Then a double deflection was carefully measured and if time per- mitted several times repeated, an observer always being at the eye-piece to see that the line should not move from the cross hairs while the micrometers were being read. Then, clamping the main circle, the grating holder was turned through 2¢ until the line was very clesely upon the cross hairs, any slight read- justments made necessary by this disturbance of the instrument were made, and the process was repeated. In this way the ini- tial line of the circle was finally reached and a value of mg _ ob- tained which depended only on the algebraical sum of the micrometer readings, always a small quantity. The determination of the temperature, a very difficult and uncertain matter in the case of glass gratings, is here compara- tively simple. A sensitive thermometer (Baudin 6156) was kept in contact with the grating, its bulb being carefully shielded _ by cotton. The construction of the spectrometer made it im- practicable effectively to shield the grating from radiation from the observer’s body; but the thermometer apparently proved effective In giving the real temperature since no discrepancies in the results could be traced to thermal causes. The thermom- eter readings were made to 0°:05, and the temperature of obser- vation rar ely varied more than two or three degrees from 20° C. The temperature being thus obtained, the necessary correction was introduced directly. into the angle of deviation. Writing the formula for wave-length in the form A=C s sin Q, where C is a factor depending on the method in which the grating is used, and differentiating we obtain “*— cot POQ, : Alin OS where if we take 1° for the temperature variation 58 the co- efficient of expansion. Whence Os e E 0g=— Got p = correction for 1° variation in temperature. For grating III for instance dg=2”-688 and by this means all the deviations were L. Bell—Absolute Wavelength of Light. B51 reduced to 20°. Writing again the equation for wave-length in the form for the method here used, c=sin @p cos 0. Now to obtain the variation in g due to a change in the angle between the telescopes, Oop=tan —~ tan 068. Taking now 0@ =1” and ¢ as found in these experiments Sp=0"089. By this means the necessary correction could be introduced in the angle of deviation, but the angle between the telescopes was so nearly constant ‘as to render this correction needless. The line selected for measurement with III was a sharp one in the green at 5133-95 of Rowland’s map. The angle 0 between the telescopes was adjusted so that in the eighth order the double deflection was 72°. Eighteen complete series of observations were then obtained, each giving a value of 10g from which the errors of the circle were completely eliminated. The results in detail were as follows, corrected to 20° on thermometer used, Date. . 1887. Nov. 2, 6, Oni 9 : 5 Os 37 ca eas 36-0 2247-410 Catia 36 0 24 -95 age Dae 362/20), 26-83 Sr iO. 50. O) 2G. oid ANG 361 Ol 28-40 NB. SG 0). Oy Be Saresl 7 4 36 On 2a 57 pony Oy 36) 0) 25-16 sor oO 360 25 -69 Gy DO). 3670) 25) <99 ph eo). (9 360.0032 oO BO, 360) .26 110 i BO 367 108 25386 B30), 36) 0.1125, -81 Deen. 36) OV 257,68 Ger els 36) 10) 725-580 The last decimal place is retained simply for convenience in averaging. The mean value of ¢ is 36° 0’ 2607 which reduced for the error of thermometer at 20° gives finally, @= 36° (0) 25" Mr: The probable error of this value is 0/14. The effect of a small error in ¢ on the resulting wave-length is given at once by OA=cos Po —. 352 L. Bell—Absolute Wavelength of Light. In this case the error introduced by an error of 1” in g isa little less than 1 part in 250000. The mean value of @ during these measurements was 6=6° 59’ 58"6. In ease of grating IV the line selected for observation was one of Rowland’s standards at w.l. 5914°319 of his preliminary list. It isa very close double, the components being distant from each other something like .,1,, of their wave-length. The double deflection was as before 72° but in the fifth order. As with erating IIT eighteen series of observations were obtained, with the fullowing resulting values of ¢ Date. g. 1887. Dec. 16, BOO Oe FE oi 16, 36 O +0 °66 co aatliGn 36 0 +0 ‘67 raat RS 36 0 +0 ‘64 cote) 36 O +1 °56 Fee 36 .0 +0 °85 i888: Jan. ZF 36 0 —1 °19 ene Dis 3620) —— orl Bar ad 1 386 0 —1 °79 wn 14 36) 10% — 1209 AL dt 34 36 O —O0 °95 He awll a 36 O —O ‘89 mesial As 36 0 —O *48 es) wea Lo 36 O —0O °59 med Sale), 36 0 —O0 °49 ee Oe 36 O +0 °51 PPADS 36) 104 — Ooh OS 36 O +0 °*55 The mean value, corrected as before for error of thermometer, is: mM P=35° 59! 59-06 +40"15 The effect of this probable error is obviously the same as in ease of grating II]. The mean value of the semiangle between the telescopes was J=3" BS Sur, During the observations with grating III the barometric height reduced to the place of observation was very nearly 762™™, but during the work with grating IV it was phenomenal- ly high, reaching an average value of 766™™, an amount so far from normal pressure as to render a small correction necessary. The mean temperature during the observations with III was about 21° C., but in ease of IV it averaged almost exactly 20° C. varying at most only two or three degrees from that figure. L. Bell—Absolute Wavelength of Light. 353 Measurement of the Gratings. The comparator on which this, the most important portion of the research, was accomplished was the same one described in my previous paper. It had however been improved in sev- eral particulars. The platform carrying the standards had been fitted with smooth rack and screw adjustments, and the microscopes and micrometers were new. The illumination of a grating under the power used,—two hundred and fifty diam- eters—is by no means an easy matter, and at the same time a powerful and symmetrical illumination is absolutely necessary for the most accurate work, particularly in case of rather small grating spaces. I had been thoroughly dissatistied with the illumination previously used—a lamp at a suitable distance— and now made a radical change. A three candle-power elec- tric lamp was attached directly to the microscope just below the eyepiece and about a foot above the objects measured. A small mirror carried by an arm screwed to the objective re- flected the beam into the Tolles illuminator. A glass bulb filled with water surrounded the light and served the double purpose of stopping radiation and partially condensing the beam upon the mirror above mentioned. IT am aware that such an arrangement is somewhat revolu- tionary, and it was only after a careful trial that I convinced myself that the heat from so near a source was not injurious. In the first place it should be noted that the lamp is only used for a few moments at a time and at intervals long com- pared with the time of observation. Thus the very minute heat wave that reaches the bar through the bulb of water can- not possibly produce a perceptible rise of temperature during the time of an observation, while during the intervals it is completely dissipated. As an experimental fact, no heating effect whatever is sensi- ble even after a whole day’s observations. To show at once this fact, and the general character of an average series of comparisons I subjoin ten comparisons of Dm,S*, with a cer- tain decimeter on glass, made at intervals of about three- quarters of an hour on two successive days. ‘The figures are taken directly from my note book. Date. Tv June 1, 1887 Dims == Go 9193 Weiiacd: s “ 4+ 91°6 fen cA: 66 6G 66 ae 22-1 17 5) (74 66 66 de 92-1 17 5) (75 66 6G ae 20°8 17 5 oe KO ce + 20°1 Wee June 2, es + 2194 EO) 66 53 14 == 91°0 ia 70) it oe SE 0) W750) 66 é 6c ee 21:0 17 “1 354 L. Bell—Absolute Wave-length of Light. The temperature was given by a thermometer in contact’ with S*, and 1d of the micrometer equalled 0:28. In a com- parison of two standards with such unequal coefficients of ‘ex- pansion as glass and speculum metal, the evil effects of radia- tion should be at their maximum, but the preceding series, including as it does all the experimental errors and showing an extreme variation of but 0:5, leaves, I think, little to be desired. The comparator was placed in a vault some six feet below the level of the street, which was provided with thick double walls with an air space between. This observing room enabled the temperature to be kept down to a daily variation of less than half a degree, the extreme range for several days being fre- quently less than that amount. Before this vault in the new Physical Laboratory was completed the comparator had been placed in an upper room of one of the old buildings, where it was well nigh impossible to keep anything like a constant temperature, particularly since the heat was unavoidably par- tially shut off during the night. Owing to this state of affairs the measurement of the gratings on which my preliminary wave-length was based, was made under difficulties and in most of the series necessarily under a rising temperature. Now when a glass standard is measured against a metal one, glass being a notoriously bad conductor, and having a very small coeflicient of expansion, if any rise of temperature takes place the length found for the glass will be too small, for re- sponding less readily to a change it will be actually measured at a lower temperature. It therefore became necessary to re-measure the glass gratings Nos. I and II, to eliminate this source of error, which was done before the results for III and IV were obtained. These gratings are very nearly 3™ long and they were therefore com- pared with successive triple centimeters of S*, until the fifteen centimeter mark was reached. Grating I was first taken in hand and six complete series of observations were obtained, each micrometer reading being the mean of several, and the extreme limits of temperature variation during the two days occupied by the comparisons being 0°°3 C. The following gives a summary of the results. 5G = 15°™S*, +19%0 )- 5G = 15™S*, + 21°5 5G — bes 2aee eal | é 56 Ligec fag poole 2 ©: 5G = 15S", 4 226 | 5G = 154820 aisksa) L. Bell— Absolute Wavelength of Light. 355 Hence combining these and reducing them to the standard temperature of 20° we have: 60000 spaces = 5G = 15°™S*, + 5/2 at 20° The micrometer constant here used was that of the new micrometer where 10 = 0-257. In precisely the same way Grating IT was remeasured, the six series giving the following relations 5G = 15™8*, 415794) 5G = 15S, + 154:9 ) 5G = 15S, Mee ce BG See a apt pee 5G = 15™S*, + 154-9 5G = 15™S*, + 162-4 | Combining and reducing these results as before we have the equation 42640 spaces = 5G = 15°™S*, + 39-9 at 20° The per peranre variation in the two days of observation was only 0°-2 Cotes III and IV were then measured. In this case a large number of comparisons were obtained at both high and low temperatures with the object of detecting any differences which might exist between the coefficients of expansion of the gratings and those of the speculum metal standards. III and LV being a little over a decimeter in length were very easy to measure, particularly since the lines were very sharp and of approximately the same width as those on the standards. III proved to have sensibly the same coefficient as the stan- dards. I subjoin the comparisons made at or very near 20°. G = Dm*, + 32°9 G) = “ + 33°0 G= ee + 32°7 G= ee + 33°2 = uC + 32°3 G= se + 32°6 G= 6e +,34°5 G= op + 33°4 Ga “ (434-2 G= ee + 32°6 Combining these and other series of observations gives finally 28418 spaces = G = Dm,S*, + 8%'5 at 20° 356 L. Bell—Absolute Wavelength of Light. It should be noted that the extreme variation in the above series is 2°2, very nearly 0/5, or one part in two hundred thousand. In the case of IV the coefficient appeared to be somewhat smaller than that of S*, The range of temperature secured was not large but as nearly as could be ascertained the coefii- cient is about 16-1 per meter per degree, while that of the standards is 17”-9 per meter per degree. However, since the measurements of g made with IV were distributed with a tol- erable degree of symmetry on both sides of 20°, any error due to an inexact value of the coefficient of expansion would appear mainly in the probable error in g The variation found would, as a matter of fact have changed the final value of ¢ by less than ()’’:2. The comparisons of IV made near 20° were as follows: - pep RPE PEP LPL PEPE E) eS We ET est Tl ++++++4+++4++4 Dw od > Or P OD Or TWWOWADOODH: wwwwnwuwww Combining these and the other observations, 39465 spaces = G = Dm;S*, + 9/1 at 20°. The probable error of the relations found for III and IV ean hardly exceed one part in a million so far as the distance between the terminal lines selected is concerned. These termi- nal lines were varied at each comparison so that while each of the above relations represents 39,465 spaces, the lines meas- ured between, though in the same vicinity, are seldom or never identical. In gratings I, II, III the number of spaces was very easily counted as the dividing engine automatically rules every hun- dredth line longer, and every fiftieth line shorter, than the others. In grating IV the number of spaces was found readily enough by ruling at a known temperature the terminal lines of a test plate almost exactly a decimeter long, and containing a known number of lines. A comparison of this with the grating gave the quantity required. LI. Bell—Absolute Wave-length of Light. B57 Calibration of the Gratings. In my previous paper the need and method of determining the errors of ruling in a grating were briefly noticed. It is fitting here to enter somewhat more into detail. The grating space is never perfectly unifcrm throughout the whole extent of the ruled surface. The variations may be in general classed as regular and irregular. In the first class we put variations in the grating space which are purely periodic or purely linear. These produce respectively “ghosts,” and difference in focus of the spectra on opposite sides of the normal. Either fault might be large enough to unfit the grat- ing for wave length determination, and would be always unde- sirable, but nevertheless would introduce no gross errors into the result. Variations of the second class include the displace- ment, omission or exaggeration of a line or lines, and what is of great importance, a more or less sudden change in the grat- ing space producing a section of the grating having a grating space peculiar to itself. The former types of accidental error, unless.extensive are harmless, and are present in most gratings usually showing as faint streaks in the ruling. It is with the last mentioned error that we mainly have to do. Consider a grating the space of which is sensibly uniform except throughout a certain portion. Let that portion have a grating space distinctly larger or smaller than that of the re- mainder of the grating. If the abnormal portion is a consid- erable fractional part of the whole grating it will, in general, produce false lines and injure or ruin the definition of the grating. Such a grating we should nowadays throw aside as useless, although many of the older gratings are thus affected. Suppose however that the abnormal portion is confined to a few hundred lines. Such a series of lines will have little bril- liancy and less defining power and consequently will simply diffuse a certain amount of light without either producing false lines or, in general, injuring the definition. In short, when the full aperture of the grating is used, the spectra produced will be due only to the normal grating space, the abnormal portion having little or no visible effect. If however we attempt to evaluate the grating space by measuring the total length of the ruled surface and dividing it by the number of spaces therein contained, we shall obtain an incorrect result, since this average grating space, including, as it does, the abnormal portion, will be necessarily different from the normal grating space which produces the spectra observed. In general if m be the total number of spaces and s the normal grating, space the length of the ruled surface will be ns+A, where A is a quantity depending on the magnitude 358 L. Bell—Absolute Wave-length of Light. and nature of the abnormal portion. It will have for its maxi- mum value 3(s—s’), where s’ is the varying grating space, in the case when the change in the space is so local and sudden as to produce no effect at all on the spectrum; and will be vari- ously moditied by the considerations now to be mentioned. If we could always assume that the abnormal portion of the grating produced no effect on the spectrum the elimination of errors of ruling would thus become comparatively simple. But in practice it is not very uncommon to find gratings in which there are several portions where the spacing is abnormal, in one case perhaps producing no effect, in a second producing false lines and in a third causing a faint shading off of the lines. For an abnormal portion will produce no effect, a slight shading or reduplicated lines, according to its extent and the amount of its variation from the normal. The following experiment will readily show the laws which govern these errors of ruling. Place a rather bad grating— unfortunately only too easily obtained—on the spectrometer, and setting the cross-hairs carefully on a prominent line, gradu- ally cover the grating with a bit of paper, slowly moving it along from one end. In very few eases will the line stay upon the cross-hairs. A typical succession of changes in the spec- trum is as follows: Perhaps no change is observed until two- thirds of the grating has been covered. Then a faint shading appears on one side of the line, grows stronger as more and more of the grating is covered, and finally is terminated by a faint line. Then this line grows stronger till the original line appears double and finally disappears leaving ‘the displaced lime due, to the abnormal grating space. This description, I regret to say, is from the examination of a grating which had been used for the determination of absolute wave-length.* This case is exceptionally complete, but even with a very good grating minute displacements can usually be noticed. When the abnormal portion is sufticiently extensive to pro- duce a faint shading along one side of the lines when the full aperture of the grating is used, the effect of the error on the resulting wave-length may be in part eliminated by the fact that the shading would displace the apparent center of the line and henee slightly change the observed angle of deviation. For this reason a grating so affected would be likely to give results varying with the order of spectrum used, since the appearance of the line would vary somewhat with the illumi- nation. It is at once apparent, bowever, that no combination of the results from different orders of spectra can possibly eliminate the class of errors we are discussing, since the alge- * Not by the author it is almost needless to add. L. Bell— Absolute Wavelength of Light. 359 braic sign of the error will be the same for all orders and it will be in every case a nearly constant fraction of the wave length. The problem before the experimenter is then the following: To detect the existence and position of any abnormal portion of the grating in use, to separate as far as possible such por- tions as produce a visible effect from those which do not, and thus finally to- determine the proper value to be assigned to the quantity A. The investigation is somewhat simplified by the fact that, for the most part, abnormal spacing occurs at an end of the ruled surface, generally at the end where the ruling was begun, since, when the engine is started it is likely to run for some little time before it settles down to a uniform state. Then, too, one is able to disregard the slight and gradual variations in the grating space which appear in every grating, since their effects will in general be integrated in the spectrum produced. It only remains therefore to study those larger and more sudden changes which can produce a sensible error in the result. It is evident that the process of examination indicated above will serve to detect the more extensive faults, together with any errors of figure in the surface, but an abnormal portion consisting of only a few hundred lines will not have resolving power enough to produce a marked effect. Making then a slit ina card just wide enough to expose a sufficient number of lines to give tolerable definition, one can examine the grating section by section, and still further discriminate between the normal and abnormal spacing, errors of figure being included as before. But as the number of abnormal spaces decreases a point will be reached when this method breaks dowa completely, and since the error in the resulting wave-length may be as large in this case as when the fault is more extended, another method must be sought. So far as I know the only method which will de- tect and evaluate all these errors is that which I have called calibration, measuring the relative lengths of grating spaces taken successively along the ruled surface. The process em- ployed was as follows. The stops of the comparator were set as close together as practicable, limiting the run of the ear- riage to a distance which varied in different cases from 4 to LO™™. Then the grating to be examined was brought under the micro- scope aud micrometer readings were taken on the lines just within the run of the carriage; the grating was then moved along about the length of the run and the process repeated till the whole grating had been gone over. The variations in the micrometer readings then gave the variations in the length of m spaces in different parts of the grating. The only assumption involved was that the variation in the different sections did not 360 L. Bell—Absolute Wave-length of Light. amount to an entire space, an hypothesis quite secure in gra- tings with spaces as large as those employed. It was thus pos- sible to determine quite accurately the variations in the grating space throughout the whole grating. It should be noted that since these variations may be of almost any kind and magnitude the errors produced by them will not in general be eliminated by combining the results ob- tained from several gratings. It may happen that the gratings used by one experimenter will have errors that will counter- balance each other, while those used by another will all have errors of the same sign. [or instance, by the merest accident the gratings used by the writer gave nearly identical results corrected and uncorrected, while those used by Peirce uniformly required a reduction in the resulting wave-length. The num- ber of gratings used by a given investigator is however so small that the errors will very seldom be eliminated, while no com- bination of the results obtained from different orders of the same grating can produce any useful effect whatever. Each of the gratings used in this research was examined minutely by the above methods and in each was found an ab- normal portion of one sort oranother. Of eight gratings which I have calibrated all have shown a similar error and of more than twenty which I have examined in the spectrometer only one (grating IIT) failed to show an abnormal section at one end. Since this is the commonest form of the error in question, it is but natural to inquire why it cannot be avoided by covering the defective end. . The reason is simple enough. By stopping out the defective portion the grating is reduced to an incom- mensurable length which enormously increases the difticulty of measuring it. A grating which is in length some convenient submultiple of a meter is easy to measure with a comparatively high degree of exactness, but one which is, say, twenty seven millimeters long, is exceedingly difficult to measure accurately since it involves a long micrometer run or the errors of sub- division down to single millimeters. It is therefore better to use the full aperture of the grating and find A by ealibration. In calibrating the gratings used, I divided I and II, which were thirty millimeters long, into six sections of 5™”, and the large eratings III and IV into centimeters. Each grating was carefully gone over five times and the mean result taken. The following corrections were found. The actual variations found in each grating are given below, the figures given being the difference of 2 lines from the dis- tance between the stops, the lines being taken in the consecu- tive sections of the gratings. L. Bell—Absolute Wave-length of Light. 361 Grating I. Sections 1 2 3 4 5 6 Residuals, 0:78 0-98 2) Oe 1:03 0°86 1°24 Grating IT. Sections 1 2 3 4 5 6 Residuals, 24-07 1:93 1°52 1°68 123 le anes Grating ITI. Sections 1 2 3 4 5 6 7 8 9 10 iResidualsy 230) eh elc7 7 22072270) 277 2:67), 2:64 9°78 enn Grating IV. Sections 1 2 3 4 5 6 7 8 9 10 Residuals, 0”:31° 0:28 \0°35 0°43 0°40 0:43 0°31 0°35 0:28 0°82 The calibration of IIL is worth describing in detail. Cen- timeter 38 was evidently too long. I therefore measured the centimeters from 15 to 25™™ and from 25 to35™". The former was quite normal but the latter showed.an increase almost iden- tical with that of the whole third centimeter. I then examined _ the grating in a strong light and detected at 27™™ from the end, a faint line, such as usually indicates a few wavering lines caused perhaps by dust under the diamond point. Placing, however, this line under the microscope a band of perhaps twenty lines appeared with spacing noticeably wider than usual. Here was a very serious flaw in a grating to all appearance absolutely per- fect. A most critical examination in the spectrometer of course failed to detect it, but it was both detected and located with unerring certainty by the process of calibration. Micro- metrical measurements on this group showed an excess of about 2"-5 over an equal number of spaces elsewhere on the grating. This quantity of course had to be taken account of in connec- tion with the previous calibration. The deduction of the necessary corrections from the data .given by calibration requires nv little care and judgment, and ean be properly done only in connection with a detailed study of the spectra given by various portions of the gratings con- cerned. For the four gratmgs used by the author, these cor- rections, applied directly to the lengths of the gratings in the form of the quantity A before mentioned, are very nearly as follows : Grating. A Ties erie emapercrm an Cee huh kt NM ae ie — 0:10 IC 01S an AIR a Vane ei yee + 0-40 oe ee PM ot FMS 5 LL MO eee a ee OQ) 362 L. Bell—Absolute Wave-length of Laight. It should be distinctly understood that the corrections deduced from the calibration are necessarily only approximate. A very minute examination of a grating on the spectrometer is impos- sible, since a small section of the ruled surface has not sufficient resolving power to give measurable spectra. On the other hand, while calibration gives the variations of the grating space with a high degree of exactness, it obviously cannot definitely decide how far these variations are integrated in the spectrum measured. Consequently while calibration will in every case give a valu- able approximation, it must necessarily leave residual errors. In these experiments the gratings were always measured par- allel to the terminations of the lines. Consequently the length of each grating as found directly must be multiplied by cos (90°—a), where a is the angle made by an individual line with the line formed by the locus of the terminations. In ease of gratings I, I, Ill this angle was found by measuring a test plate as described in my previous paper and was found to be within a very few seconds of 89° 56’. Grating IV ruled on the new engine was tested by measur- ing the sides and diagonals of the ruled surface and gave an al- most exactly identical value of a. No correction therefore need be introduced for this cause, since cos (90°—a) does not differ sensibly from unity. Final-result for Absolute Wave-length. Only one equation needs to be added to those already given for $*,. This is the one for the third 5™ space, necessary to de- termine the absolute length of the first 15°". 5°, (8) and (4) were compared and the following relation was found between them: (4)=(8)+0"-4. The relation found in 1885 was (4)=(8)+1"%1. Consequently (8) has not sensibly shortened and nearly the whole change found in S*, has taken place in the last five centimeters. Writing now the absolute lengths of Dm, S*, and 15cm. 8?,, Dm, S$*,=100:00666™™ at 20m 15cm S?,=150°00897 at 20°. Applying now the relations found for grating I in the fore- going section, 8 = 0°002500226™™ And since @ = 45° 1’ 487:24 A = 5896°18 Similarly for grating IT, ‘ $ = 0°0038519041™™ y = 42° 4' 59'-28 4 = 5896°23 L. Beli—Absolute Wave-length of Light. 363 _Computing the similar quantities for the speculum metal gratings III and IV, for grating ITI, $ = 0:0035193858™™ OQ) = BE" 0 Qaeg 6 = 6° 59’ 58"°56 A = 5133°89 and for grating IV, 8 = 0°002534506™™ @ = 35° 59! 59"-06 O69 Be Bt A = 5914°37 Reducing now these latter wave lengths to the corresponding values of D,, introducing the barometric corrections and com- bining, the final results for that line are Grating W.L. cS i Ges ade st ay IRR RUS) eae Un 5896°18 V0 ie coe UN aruda AR ML SCHL a ea 5896°23 ALLS epee cen nh Pe Nia sn Get eee UM A oa 5896°15 SIN ape cera ernie toh ee rh AL nea PM ten SO Cela 5896°18 in air at 760™™ pressure and 20° C. temperature, or 272 vacuo, Pp p ; 589790 It is no easy matter to form an estimate of the probable error of this final result. So far as errors of observation go, the result should be correct to within one part in half a million, but there are so many complex sources of constant errors in this problem that such a statement means little. My present result exceeds the estimated probable error of my former result considerably, though it falls within the limit set by Prof. Rowland and my- self for the possible error and noted in his paper on “ Relative Wave-length” of the same date as my own. The cause of this discrepancy is partly due to the varying temperature under which the glass gratings were first measured, and partly to the change in the value assigned to the standard of length.* Then too, the corrections applied to gratings II and III may be slightly in error. Taking into account all these sources of uncertainty it is my opinion that the above final result is not likely to be in error by an amount as great as one part in two hundred thousand. =. * In terms of the length I originally assigned to S*, the wave-length of D, would be 5896°14, while if the value deduced from the Berlin comparison were taken it would be 589622. The wave-length quite certainly lies between these values, but the proper weight to be given to the Berlin comparison relatively to the others is rather uncertain. AM. Jour. Sc1.—Tuirp SERIES, VOL. XXXV, No. 209.—May, 1888. 2 364 L. Bell—Absolute Wave-length of Light. Taking the above value of the absolute wave-length and ap- plying the appropriate corrections to some of the fundamental lines given in Prof. Rowland’s paper (this Journal, March, 1886) the wave-lengths of the principal Fraunhofer lines in air at 20° and 760™™ are, A (aN ane, BAS ye a aU ie pe MEN MLE) ol Tb ite ini lub Liz T| ODT! B and ‘‘tail ? of group 66 Oper RTO MIA vate een NaN al'a(GVEVSZbor| Fl CST eS 2 SOE (ENS RRS nln mA cee tee 6563°07 AB see eed ec) Ucn ok NOISE Mek fs ea LA 5896°18 ip SPANO aye Ula relapse fas yes Lee game eae PAILS 5890°22 | Dg eres Mey era his Pi se hae 5270°52 Ve MPAEAL MAGUS RL Ay at erp rad iy seer th Soe gnS 5269°84 Dees EA aa RG Ae noe eee IE Oe | SoS Wate ARGC a EMR MEU C ae Alyn ge a eae 8) ce 4861°51 Comparisons between these wave-lengths and the older ones become somewhat uncertain toward the ends of the spectrum since the appearance of lines like A, b, G and H vary so much with the dispersion employed. The relative wave-lengths above given are certainly exact to within one part in half a million. It may not be out of place here to discuss the most recent work on this problem. Just before the publication of my first paper the very elaborate paper of Miiller and Kempf appeared. Their work is a monument of laborious research and it is unfortunate that so much time should have been spent in experiments con- ducted with glass gratings of small size and inferior quality. Since the invention of the concave grating, it is a waste of en- ergy to make micrometric measurements with plane ones, and this statement could hardly be corroborated more strongly than by the relative wave-lengths given by Miller and Kempf. The. probable error of their wave-lengths is in general not less than one part in two hundred thousand. That the value assigned by them to the absolute wave-length is as near the truth as it probably is, is due to no lack of faults in the gratings. Their results tor the line D, were as follows: ‘ Grating. W.L. COLO Tey al 7a ean Aileaesg gery eed ip Me etna ak aN YD 52896°46 IRS Cy OT 22, Wee CHL i cic tre NY bs RS le Pa a 5896°14 S281) Olle re zack eel oy Stine oe Pale i ae 5895:97 CST OYINIL! Bee bone wee ty am ermine Junta Reno A discussion of these errors as exemplified in the paper under consideration would take up too much space to be in- serted here, but one or two points are worthy of notice. When a grating gives different results in the different orders, it is evident that there are in it serious errors of ruling, and the maximum amount of the variation will give a rough esti- L. Bell—Absolute Wave-length of Light. 365 mate of their size as compared with those of other gratings. Applying this test, the four gratings rank as follows: “5001,” “8001 L,” “2151,” “8001,” where the first which gave for the w. 1. 5896°14, had no sensible variation in the different orders and the last, which gave 5895-97, varied in the most erratic fashion. It by no means follows, however, that because a rating gives identical results in the various orders, it is there- ie free from errors of ruling. Witness Grating III of this paper in which the error was of a kind which could not be de- tected at allin the spectrometer. Yet it was large enough to give, if neglected, 5896-28 for the wave-length of D,.* Speak- ing of errors in gratings a case in point is the work of Peirce. On account of the reasons heretofore noted Peirce’s standards of length are somewhat uncertain in value so that no definite correction can be as yet applied to his wave-length from this eause. Three of his gratings, however, I have calibrated, and each of them showed an error tending to diminish the wave- length. If the mean result obtained from these had been assumed to be correct it would have been equivalent to the introduction of a constant error. Peirce’s preliminary result is for this reason too large by more than one part in a hundred thousand; how much more, it is impossible to say without knowing the results obtained from each grating and so being able to apply the corrections found. Peirce’s method was such as should have secured very excellent results and such will undoubtedly follow a further investigation of the stan- dards and gratings. Still another recent determination is that by Kurlbaum, who used two good sized speculum metal grat- ings and measured them with particular care. Like the previ- ous experimenters he neglected, although he did not ignore, the errors of ruling and consequently the results he obtained are somewhat in doubt. A serious objection, moreover, to his work is the very small spectrometer he used. To undertake a determination of absolute -wave-length with a spectrometer reading by verniers to 10’’ only, and furnished with telescopes of only one inch aperture is simply courting constant errors. More especially is this true since it would be hard to devise a method more effective in introducing the errors of ruling, than to use a grating with telescopes too small to utilize its full aperture, and then determine the grating space by meas- uring the total length of the ruled surface. Kurlbaum’s grat- ings, too, were of an unfortunate size, 42 and 43™™ broad respectively, and consequently by no means easy to measure. On the whole his result, 5895-90 is not surprising. *The results given by the gratings used by the author, neglecting the correc- tion A would be as follows: I, 5896°20; Il, 5896714; III, 5896:28; IV, 5896712 Curiously enough the mean would be practically unchanged. 366 L. Bell— Absolute Wave-length of Light. The agreement of relative wave-lengths as determined by different experimenters unfortunately gives no measure as to the accuracy of the work. The relative wave-lengths as de- termined by Miiller and Kempf and by Kurlbaum agree in gen- eral to within 1 part, in 100,000: the absolute wave-lengths assigned by these experimenters vary by more than 1 part in 30,000. A very ingenious flank movement on the problem of abso- lute wave-length has been made by Macé de Lépimay. His plan was to use interference fringes in getting the dimensions of a block of quartz in terms of the wave-length, and then to avoid the difficulties of the linear measurement by obtaining the volume through a specific gravity determination. His re- sults do not indicate, however, experimental accuracy as great as can be obtained by the usual method, and the final reduc- tion unfortunately involves a quantity even more uncertain than the average standard of length, i. e., the ratio between the meter (?) and the liter. It may be interesting here to collect the various values which have been given for the absolute wave-length within recent years. Results are for the line D.. TUT RS( CE Wet er ANNAN MS WAL Ginnie pa IN A Oe Ne asic OVAL OG) Wianr der vy ulliore iy ai tatu siesta Neha eee 5898°6 Angstrom SUS le ONE en a NMC Be NIU 5895'13 IDIES CHET TAS ee URN Te ee a ea i MN See een Ope AP ELEC OE Ay OES SIRS AN een onic CAN ne aoe 5896°27 ngstrém corrected by Thalen_-___------ 5895°89 © Mrtiller an delenn pte eyes Asie eases a 5896°25 Miaeeidies Ti ep iiney cls oe nae ee eae Reva 5896:04 AE ectsne iho earn SE RGU AP Ra 5895:90 Bel Muar anne PR a AMR Ue AlN Ue ode hehtts SUR as Rafe aes A ae 5896°18 These figures are discordant enough. When beginning the present work, I had hoped that it would prove possible to make a determination of absolute wave-length commensurate in accuracy with the relative wave-lengths as measured by Prof. Rowland. This hope has proved in a measure illusory, by reason of the small residual errors of the gratings and the oreater uncertainty involving the standards of length. I feel convineed, however, that the result reached is quite near the limit of accuracy of the method. It should be remembered that any and every method involves the uncertainty of the standards of length, an uncertainty not to be removed until a normal standard is finally adopted and exact copies of it dis- tributed. And as far as experimental difficulties are con- cerned, the next order of approximation will involve a large number of small but troublesome corrections, such as the effect , Mc Gee—Formations of the Middle Atlantic Slope. 367 of aqueous vapor on atmospheric refraction, varying baro- metric height, the minute variations in the grating space, failure of thermometer to give temperature of grating exactly, and countless others which will suggest themselves only too readily. Aside from the use of gratings, decidedly the most hopeful method as yet suggested is that due to Michelson and Morley.* Theoretically the plan is particularly simple and beautiful, con- sisting merely in counting off a definite number of interference fringes by moving one of the interfering mirrors and measur- ing, or laying off upon a bar, the resulting distance. The mechanical difficulties in the way, are however formidable, and whether or no they can be surmounted only persistent trial can show. The possible sources of error are of much the same type and magnitude as those involved in the comparison of standards of length, and if these errors are avoided, the uncertainty concerning the standards still remains. Whether or no the practical errors of the method are greater or less than with gratings only experience can prove. Certainly if the method is capable of giving exact results it is in the hands of one able to obtain them from it. In closing this paper I can only express my sincerest grati- tude to the various friends who have done all in their power to facilitate my work, and especially to Professor W. A. Rogers who has been tireless in his endeavors to determine the true value of the standards of length; to Mr. J. S. Ames, Fel- low in this University, who has given me invaluable aid in the work with metal gratings ; and to Professor Rowland who has furnished all possible facilities and under whose guidance the entire work has been carried out. Physical Laboratory, Johns Hopkins University, March, 1888. Art. XXXI—Three Formations of the Middle Atlantic Slope; by W. J. McGrr. (With Plates VI and VIL) (Continued from page 330.) THe Cotumpia FoRMATION. General Characters.—The Columbia formation exhibits two phases which, although distinct where typically developed, inter- graduate. The thicker and more conspicuous phase occurs com- monly along the great rivers at and for some miles below the fall line, and may be designated the jiwvdal phase; while the thinner generally forms the surface over the remainder of the Coastal plain, and may be designated the interflwvial phase. * This Journal, III, xxxiv, 427. 368 W. J. McGee—Three Formations of The first phase is bipartite, the upper division consisting of massive or obscurely stratified brick clay, loam, and fine sand, and the lower of stratified and cross laminated gravel and coarse sand, containing abundant erratic bowlders; while the second consists of an indivisible bed of gravel, sand, clay, etc., chiefly of local origin and thus varying from place to place though tolerably homogeneous in each exposure. The ‘first phase, too, is confined to limited altitudes, approximately con- stant on each river but rising northward, while the second occurs indiscriminately at the highest and lowest altitudes within the Coastal plain, its thickness culminating at the lower levels and along the coast. The Fluvial Phase.—The bipartite phase of the formation is well developed along all of the larger rivers of the Middle Atlantic slope, but most characteristically and extensively on the Potomac, the Susquehanna, and the Delaware. The deposits on the Potomae.—Washington lies within a rudely triangular amphitheater opening southward, into which the Potomac falls from the northwest and the Anacostia from the northeast, the former passing from torrential to estuarine condition and turning southward within the limits of the city. The western side of the amphitheater is the Piedmont escarpment, which south of the city is a terraced or irregular slope rising to a somewhat undulating plain 200 to 425 feet in altitude; the eastern side is the line of bluffs overlook- ing the Anacostia and rising into two broad terrace plains 175 and 275 feet in height respectively; and the northern con- fine is the deeply ravined margin of a terrace 200 feet in alti- tude stretching from the breach made by the Potomac in the Piedmont escarpment directly eastward to the broader valley of the Anacostia three or four miles above the confluence. The floor of the amphitheater is a series of low terraces rising from a few feet below to about 100 feet above tide, the most conspicuous two being about 40 and 80 feet in altitude re- spectively. ‘To the southward the amphitheater opens into a broad valley occupied partly by the Potomac estuary and partly by a low but extended series of terraces, of which the best developed members are about 20 and 40 feet above tide respectively. Throughout this amphitheater the fluvial phase of the Columbia formation is the prevailing superficial deposit up to 150 feet above tide; except where manifestly eroded or buried beneath modern alluvium, it is everywhere exposed ; all of the lower and many of the higher terraces are built of it; and it unquestionably lines the estuaries of both the Potomac and the Anacostia beneath the recent alluvium. The relation between the deposit and the topographic configuration is striking, and the Middle Atlantic Slope. 369 too intimate to be fortuitous. Everywhere west of the Ana- costia-Potomac channel (the deposit does not occur east of the rivers) the limiting boundary of the fluvial phase of the forma- tion is the 150 foot contour; and the limit within which it ex- hibits a certain notable and well defined type is the 90 foot contour. Within the amphitheater the formation varies considerably in structure and composition and in the relative thickness of the two members—the basal member being best developed centrally and near the entrance to the Potomac gorge, and the superior and finer member reaching the best development and greatest volume peripherally and at points distant from the gorge. The section in the central part of the city of Washing- ton is, however, typical; and two exposures so located, which together form a general section of the fluvial phase of the for- mation, are shown in the accompanying plates. Plate VI is reproduced mechanically (by the Moss process) from a photograph of the exposure on the north side of E street between 1 and 2 southeast. The upper member is homogeneous loam, rather too sandy for use as a brick clay, either massive or obscurely stratified, containing a few small pebbles irregularly disseminated er arranged in layers. On mechanical analysis the loam is found to consist of (1) fine silty or clayey particles of impalpable fineness, intimately mingled with (2) sand grains of variable size, form and composition, and with (3) gravel of all sizes from that of coarse sand to that of the pebbles shown in the plate; the relative proportions being perhaps 50 per cent of impalpable clay and silt, 35 or 40 per cent of sand grains up to ¥ inch in diameter, and the balance gravel grains and larger pebbles. The homogeneous loam graduates down- ward imperceptibly into obscurely stratified sandy and gravelly loam in which sand from ¢ inch downward constitute some 40 per cent, gravel from $ inch upward about 30 per cent, pebbles from an inch upward perhaps 20 per cent, and impalpable silt not more than 10 per cent of the volume—the structure re- maining unchanged save that the stratification becomes more and more distinct toward the base. The gravelly loam grad- uates in turn into a bed of stratified sand and fine gravel, sometimes cross-laminated, with occasional pebbles up to 8 or 4 inches disseminated through it. This bed is practically des- titute of impalpable silt, and is screened for building sand. The stratified sand passes rather abruptly, but with some interstrati- fication, into a heterogeneous mass of coarse sand, gravel, pebbles and bowlders up to a foot in diameter. Plate VII, also reproduced mechanically from a photograph, supplements Plate VIL The exposure occurs on the opposite side of the street and, extending nearly to the base of the Co- 370 W. SJ. McGee—Three Formations of lumbia formation, exhibits the typical aspect of the lower member—the greater part of the superior loam having been artificially removed long before the recent excavation was made. The uppermost stratum consists of pebbly and sandy loam corresponding to but somewhat coarser than the basal por- tion of the upper member in Plate VI; and in this section, too, the stratum graduates insensibly into stratified sand, which in turn passes imperceptibly into the gravel bed at the summit of the lower member. The gravel deposit constituting the lower member is dis- tinctly but irregularly stratified and rather indefinitely tripar- tite. The uppermost stratum is a bed of gravel and sand similar to but thinner than that above the stratified sand, con- taining rounded and sub-angular bowlders up to over a foot in diameter (commonly arranged in beds), lenticular layers and pockets of sand, ete; the next stratum is a regularly bedded mass of clay and loam, evidently derived largely from the Potomac formation, which is locally inclined; and finally at the base there is another bed of gravel (imperfectly shown in the plate) resting on an irregular surface of purple-brown Potomac clays. ~ Combining the three strata and analyzing their constituents, it is found that perhaps 20 per cent consist of pebbles and bowlders from an inch to a foot or more in diameter, some 25 per cent of gravel and pebbles from $ inch» to one inch in diameter, about 30 per cent of finer sand, and the remainder (including the redeposited Potomae clay) of impalpable silt or clay; and examination of the pebbles and bowlders shows that nearly all of the larger are angular or sub- angular and either of Piedmont gneiss or of quartz undis- tinguishable from the vein quartz of the Piedmont zone, while 75 or 80 per cent of the smaller are well rounded and of quartz and quartzite similar to those of the lower member of the Po- tomaec formation. These sections oecur about three miles southeast of the gap eut by the Potomac river in the Piedmont escarpment, and in the line of the old outer gorge. Nearer the gap the superior member attenuates, and the gravel bed thickens and becomes coarser until in some sections ‘fully one-half of the formation is made up of pebbles and bowlders up to four or five feet in diam- eter; to the eastward the loam increases in thickness and homoge- neity, its pebbles disappear, and the stratification becomes more regular, while the basal member attenuates and the pebbles and bowlders of which it is composed diminish gradually both in size and abundance; to the southward and further from the gap the upper portion of the loam is a homogeneous brick clay, its lower portion is a stratified sand, and the lower mem- ber of the formation is represented only by a thin bed of the Middle Atlantic Slope. 371 gravel and small bowlders; and still further southward, as at Alexandria, the superior loam becomes fine and silty, and there is but an inconspicuous ‘bed of pebbles, with no large bowlders, at the base. Most of the materials composing the formation in the Wash- ington amphitheater may be readily traced to their sources : nine tenths of the larger angular and sub-angular bowlders are either (1) gneiss identical with that exposed in the gorge ot the Potomae river within a few miles to the westward, or (2) quartz undistinguishable from that of the veins intersecting the gneiss; the well rounded quartz and quartzite pebbles are indistinguishable from those of the Potomac formation, and indeed in some cases Potomac outliers unquestionably a situ graduate insensibly into taluses which descend the slopes and in turn graduate into the Columbia gravels; the intercalated layers of plastic clay and accumulations of arkose are litholog- ically identical with certain characteristic phases of the Potomac formation; the sand, clay and loam sometimes resemble the residuary products formed by the disintegration of the adja- cent Piedmont gneisses 7m sztw so closely as to be distin- guished only by structural features ; and in all cases the petro- graphic identity is unquestionably indicative of the source of the material. The Genesis of the Deposits—An essential element in any philosophic classification of the rocks of the earth is genesis, and geologic science has now reached a stage in which processes and products, agencies and results, are commonly correlated, and in which at least the broader classifications are genetic. There are recognized five principal categories of agencies by which the various superficial deposits of the earth are produced, viz: chemic, igneous, glacial, aerial and aqueous. Now on comparing the upper member of the fluvial phase of the Columbia formation with the known products of each of these categories of agencies, it becomes evident that the de- posits were not produced by either of the first two classes of agencies, since they have no distinetive features in common with chemie and igneous deposits; that they are not glacial, since they are too regularly and continuously stratified, since the two members are distinct in structure and composition and yet intergraduate, and since the pebbles and bowlders are neither striated nor polished ; that they are not aerial since the materials are coarser and more continuously bedded than those transported by winds; and hence that the deposits are aqueous in origin. By legitimately extending the same process of reasoning it might equally be shown that they are not fluvia- tile, torrential, lacustral, nor marine, and indeed that they can only be a sub-estuarine delta of the river on which they occur. 372 W. J. McGee—Three Formations of The same conclusion is reached by the converse process of reasoning. At Washington the Potomac river passes from fluviatic to estuarine. condition, and the materials trans- ported by the river proper are precipitated in the estuary. The opportunities for examination of these sediments are lim- ited, because they are seldom exposed above tide level (sub- aerial alluvium being significantly absent along the fall line margin of the Coastal plain); but the numerous borings made in engineering operations indicate that the sub-estuarine de- posits opposite Washington consist predominantly of fine silt or clay, and subordinately of sand and gravel, with occasional pebbles and bowlders of considerable dimensions either seat- tered or in beds. In brief, the deposits of the Potomac estuary of the present at Washington differ from the upper division of the fluvial phase of the Columbia formation only in the larger proportion of silt and the smaller size of interspersed bowlders; and below Washington the modern estuarine de- posits become progressively finer to and beyond Alexandria, just as do the deposits of the Columbia formation. Now the precise conditions of genesis of the modern sub-estuarine de- posits are known: the silt is carried down the river and into the estuary at all stages but most abundantly during freshets to either settle immediately in the slack water or sweep back and forth with the tide until flocculation and more gradual depo- sition finally take place; the fine sand is similarly transported into the estuary and dropped toward its head; most of the coarse sand, gravel and pebbles are swept over the falls or collected in the gorge of the Potomac by the raging torrent which the river becomes during its freshet stages, and are quickly depos- ited in the upper part of the estuary ; while the larger pebbles and bowlders, together with some or the smaller, are gathered along the river and floated into the estuary by the ice floes with which the torrent is laden during spring freshets; and the distribution of the various materials, fine and coarse, is affected by the strength of the currents, by local eddies and basins, and by distance below the mouth of the gorge, while the area of deposition is determined by present tide level. Were the land in the vicinity of Washington to be elevated 150 feet, and were this level to be maintained until the sub-estuarine ceposits now in process of formation were dissected by erosion, desic: cated by draining, and decolored by oxidization, they would unquestionably form a homologue of the upper member of the ‘Columbia formation, differing from it only in coarseness of materials and in geographic extent; and the modern deposit, like the older, would rise upon the valley sides to the shore line contour, and its surface would similarly form a broad ter- race plain. the Middle Atlantic Slope. 373 The altitude of the old delta now exposed as the Columbia formation indicates submergence of about 150 feet during the period of its deposition ; and such submergence is attested not only by the deposits but by an extensive system of terraces. The Columbia formation itself forms, within the Washington amphitheater, two distinct terrace plains, modified by erosion and culture yet each miles in extent, together with several others of less area; the upper level of the deposit is marked by broad shore lines on both sides of the head of the estuary and by a rock shelf in the gorge of the Potomac half a mile in average width and fifteen miles long; southwest of Washing- ton there is a wave-fashioned plain, 220 feet above tide, which is more than twenty-five square miles in area and so little modified by erosion that considerable tracts are imperfectly ‘drained; a more deeply ravined plain of like altitude five square miles in area forms the marginal portion of the Pied- mont plateau to the northward of Washington; beyond the Anacostia there are equally distinct terrace plains, that of 175 teet above tide at St. Elizabeth’s Insane Asylum being so imper- fectly invaded by erosion and so level to the very verge of the river bluffs that drainage is imperfect over fully a square mile of its area; and in many other localities, and at all altitudes up to 250 feet or more, broad terraces abound. The extensive ter- racing of the tract gives origin to a striking topography of plains and scarps, through which profiles, drawn in any direction, ex- hibit characteristic combinations of horizontal lines and steep slopes. Independently of the deposits, the terraces and shore lines in the Washington amphitheater prove submergence of the land to a depth of over 250 feet—the deposits at the high- est levels representing rather the interfluvial than the fluvial phase of the Columbia formation. While nothing more than comparatively brief submergence of 150 or more feet was required to produce the upper member of the Columbia formation; other conditions were required to produce the coarse lower division, which differs materially in composition from the sediments now laid down in the Potomae estuary ; but since the abundance and size of the pebbles and bowlders now swept into the estuary are determined by the amount and thickness of the ice floated into it during the spring freshets, it is evident that the chief additional condition required for the deposition of the coarse materials of the older formation was diminution of temperature and consequent in- crease in floe transportation with, perhaps, concurrent strength- ening of fluvial currents. It might accordingly be safely in- ferred from the phenomena of this tract alone that the lower member of the formation was deposited during a period of low temperature. The refrigeration thus suggested by the depos- 374 W. SJ. MeGe—T. hree Formations of its of the Potomac river is proved by those of the Susquehanna and Delaware ; and since the bowlders of the lower Columbia at Washington are fully twenty times as large and abundant as those brought down in the spring freshets of to-day, the diminution in temperature must have been considerable. In brief, it is evident that the Columbia formation within the Washington amphitheater is a sub-estuarine delta deposited when the sea rose at least 150 feet higher, and the temperature was considerably lower, than to-day. The Deposits on the Susquehanna.—A bout its locus of tran- sition from fluvial to estuarine condition (for Chesapeake bay is simply the estuarine portion of the river), the Susque- hanna is flanked by an extensive bipartite deposit, the upper member of which consists of loam with occasional disseminated pebbles and small bowlders, while the lower is a great mass of coarse sand and gravel interspersed with: large bowlders. The distribution of the deposit, vertical and horizontal, is limited by the 240-foot contour, and it is typically developed only be- low the 120-foot contour; the most abundant materials of determinate source are bowlders from the Piedmont and Appa- lachian regions, and well-worn quartzite pebbles from the sub- jacent Potomac formation; the entire area is extensively ter- raced; and in general the phenomena duplicate those of the Potomac river. They are described in detail and fully illus- trated elsewhere.* Certain minor differences between the Susquehanna and Po- tomac deposits are noteworthy. The former reach far the greater volume, the thickness being thrice and the area twice as great as on the Potomac; the bowlders of the lower mem- ber are much larger—the largest being from 100 to 200 eubie feet in dimensions, or fully three times as large as those found on the Potomac and 50 times as large as those now transported into the bay in vernal ice-tloes; the materials of the upper member are finer than on the Potomac, and consist in part of mechanically divided but undecomposed carbonate of lime, which either forms a caleareous cement or segregates into cal- careous nodules resembling loess-kindchen ; indications of ice- berg action are found in the deposits; and a much larger pro- portion of the pebbles and bowlders of friable rock are sharply angular and evidently ice-transported. The resemblances be- tween the deposits on the two rivers in structure and composi- tion, in geographic and hypsographie distribution, and in all other distinctive characters, indeed, prove that they are homo- genetic—i. e., that the Columbia formation on the Susquehanna * “ Notes on the Geology of the head of Chesapeake Bay,” 7th An. Rep. U.S. Geol. Survey (in press). & the Middle Atlantic Slope. 375 as on the Potomac is a sub-estuarine delta laid down during a period of cold and submergence; and the differences prove that the submergence and the refrigeration were both the greater on the former river. Above the fall-line the Susquehanna, unlike the Potomac, is flanked by deposits corresponding to the sub-estuarine delta. Between Columbia and its mouth, it is true, the river flows rap- idly through a steep-sided gorge of considerable depth, the tribu- taries have high declivity, and superficial deposits are not pre- served; but above Columbia the valley widens, its slope di- minishes, and remnants of slack water deposits appear. Four miles above Harrisburg the river breaks through Kittatinny mountain in a widely-known water-gap, and embouches upon a slightly undulating terraced plain 100 to 200 feet above its level; and the prevailing superficial deposit over this plain is loam or brick clay passing down into a gravel or bowlder bed. A representative section of the prominent terrace half a mile northeast of Harrisburg is as follows: 1. Fine loam, massive above and horizontally laminated below, with a few disseminated pebbles and layers of sand toward the base, largely used as a brick clay_------ .-- ous iteet. 2. Irregularly stratified gravel, comprising pebbles (commonly rounded) from 3 inches downward, imbedded in a matrix of coarse brown sand, the shale deeply ferruginated and SOMetIMesceMente dius te Nien ai soe! eee A feet: 3. Stratified coarse brown sand abounding in pebbles and Ry Oywl le rr siete ses spa nupee eee Oe et oo cline G/L ea Ot TCC EL The three members are here sharply demarked, but elsewhere intergraduate. Save that these deposits at Harrisburg are somewhat thinner, that the bowlders are smaller, and that they are without Pied- mont crystallines, they are scarcely distinguishable from those about the head of Chesapeake bay. There is the same brick-red color, the same degree of ferrugination, the same _ bi- partition and the same structure in each member, the same black ferruginous cement uniting and staining the pebbles, the same intergraduation of the members, and indeed so close similarity in all essential respects that either deposit might be accepted as the type of the other. And the deposits at Harris- burg are representative of those of a considerable area: the tract mantled with brick clay and gravel on the north side of the river below the Kittatinny water gap is 10 miles long and 5 miles wide, and the area of the deposits on the south side of the river is nearly as great. Above the water gap the de- posits are still more largely developed; mile after mile the Susquehanna is flanked by gently sloping plains descending 376 W. J. McGee—T. ies Formations of nearly to the river and then dropping suddenly to its flat bottomed gorge, and everywhere except in the sharper ravines and larger tributary valleys the deposits prevail, and the alti- tude to which they rise progressively increases up the river; within its hypsographic limit the formation in the Susque- hanna valley is nearly as continuous and distinctive as the gla- cial drift of the northern part of the state, and its influence upon the industries of its area is equally important. The relations of these deposits to the terminal moraine and the relations of both to the topography are significant, and are well exhibited in the Susquehanna valley about Berwick and Bloomsburg. The broad features of the region, like those of the inter-montane Appalachian valleys generally, comprise old base level plains of considerable uniformity, bounded by moun- tain ranges, sharply incised by waterways cut down to a newer base-level. The principal waterway is the broad, steeply bluffed outer gorge of the pre-morainal Susquehanna. This gorge is partly filled with the overwash gravels from the mo- raine; and in these gravels the narrow inner gorge of the present river is excavated. Three miles above Bloomsburg the old base-level plain is 5 or. 6 miles wide, gently undulating, and 200 to 300 feet above the river, which follows its southern side (fig. 1). The entire plain is covered with a sheet of fine loam or brick clay similar to that of Harrisburg, and like it graduating downward into stratified sand or gravel containing well rounded bowlders of quartzite and other sub-local rocks up to a foot or more in diameter. On approaching the river this plain breaks down sharply in an abrupt escarpment, 75 to 100 feet high, over- looking the pre-morainal valley, the loam and gravel extending to the verge of the escarpment but failing below. This outer MONTOUR RIDGE CATAWISSA HILLS © + oon anne enn nn eee ee nen = =~ == BASE-LEVEL PLAIN Fig. 1.—Cross-Section of Susquehanna Valley between Bloomsburg and Berwick. valley of the Susquehanna is perhaps one and a half miles wide, and is lined to an undetermined but considerable depth with rounded pebbles and cobbles, sometimes interstratified with or overlain by fine gravel, sand or loam—the whole rep- resenting the overwash materials from the terminal moraine ; and the valley bottom descends by step-like terraces of won- derfully sharp contour and fresh aspect to the narrow inner gorge within which the river tumbles and dashes over a bed of simi- lar pebbles and cobbles. South of the river the surface rises the Middle Atlantic Slope. 377 rapidly to the plateau-like summit of the Catawissa hills; and patches of loam similar to that forming the surface north of the river occasionally appear on the slope from 100 to 250 feet above the channel, and the hill-tops, 500 feet and less above the river, are dotted here and there with well rounded quartzite pebbles and bowlders two feet or more in maximum dimensions ; the isolated loam patches and scattered bowlders alike rep- resenting residuary traces of a once continuous formation now largely removed. The overwash gravels are stratigraphically continuous with and graduate imperceptibly into the terminal moraine, and are manitestly the product of a rapid glacier-born stream with considerable declivity. The loam of the base-level plain, on the other hand, is unquestionably a deposit of slack waters ; but it contains a notable element of partly oxidized rock-flour (like that found at the head of Chesapeake bay), evidently of glacial origin. Moreover, the high-level bowlders at the base of, or incorporated within, the loam are much larger than those _transported by the present river, and were.evidently distributed by floating ice of greater thickness than that now formed in the same region. Both members of the formation thus attest contemporary climatal refrigeration. ; As already indicated the high-level loam of the Bloomsburg- Berwick section is continuous—save where locally cut off by mountain ranges rising above its altitude—down the river to Harrisburg, and the residuary cobbles and bowlders occur at intervals over the slopes and within the inter-montane valleys from which the loam has disappeared; while the newer over- wash gravels attenuate, their altitude diminishes, the materials become finer, the terraces merge and finally disappear, and the entire deposit fails above river level and the inner gorge is completely iost, about the confluence of the Western Branch at Northumberland. Traced up stream the loam and the residuary bowlders of the Columbia formation persist to the terminal moraine where the soft contours of the loam-mantled plain dis- appear beneath the knobby-surfaced moraine, and beth loam and bowlders are incorporated in the moraine: material ; while the overwash gravels lining the outer valleys lose their distinct terracing, the cobbles increase in size and become less and less perfectly rounded, the materials become more and more hetero- geneous until they too merge into the terminal moraine, and the entire valley is finally filled with aqueo-glacial gravels to a height of 250 or 275 feet above the present level of the river and to an unknown depth below. While the gravel and cobble deposit is simply the overwash from the terminal moraine, the loam and high level residuary gravels evidently represent a distinct and far older formation : 378 W. J. McGee—Three Formations of the older deposit is bipartite, while the newer is indivisible; the loam of the older is unquestionably a slack water deposit, while the weil rounded pebbles and cobbles of the newer were just as unquestionably assorted and deposited by rapid cur- rents; the older deposit rises to altitudes of 500 feet above the level of the river, while the lower attains a maximum altitude of only 275 feet ; the outer gorge of the Susquehanna has evi- dently been excavated in obdurate paleozoic rocks since the older deposit was laid down, while the work of the river since the deposition of the newer has been limited to the excavation of the far smaller inner gorge in unconsolidated gravels; the older deposit has been deeply dissected by the tributary water- ways, and its slopes are softened and its escarpments rounded by weathering, while the same tributaries, despite their high de- clivity, have eut but trifling channels in the newer deposits, and the terrace scarps yet remain sharp-cut; the older deposit is everywhere deeply oxidized and ferruginated and its exposed bowlders of obdurate quartzite decolored and sometimes disin- tegrated, while the materials of the newer deposit are fresh and bright; and the older deposit everywhere passes beneath the terminal moraine into which the newer merges. The relation of the loam and high level bowlders to the valley of the Susquehanna is significant. The river of the present is commonly unnavigable, and flows in a succession of rapids and intervening pools in a broad, shallow, rock-bottomed channel, with an average declivity of over two and one-half feet per mile: it is preéminently a transporting and corrading stream; and its local and temporary deposits are coarse, Yet the loam by which the valley sides are lined is evidently a de- posit of slack waters, and the associated cobbles and bowlders appear to have been dropped from floes floating upon com- paratively still waters; and the altitude of the deposits pro- gressively increases northward. To produce such a change in the regimen of the Susquehanna as the Columbia phenomena indicate would require submergence of 240 feet at its mouth and fully 500 feet at the terminal moraine, and the transforma- tion of its rock-bound gorge into an estuary, tidal to the Kitta- tinny water-gap at least. The testimony of the Susquehanna phenomena corrborates and supplements that recorded in the Washington deposits, in that they are not only indicative of land submergence and co- eval cold but prove (1) that the period of submergence was one of northern glaciation, (2) that this glacial epoch was long anterior to the one during which the terminal moraine was formed, and (8) that the submergence increased northward. The Deposits on the Delaware.—As shown by the researches of Lewis and Chester, at Philadelphia and in northern Dela- the Middle Atlantic Slope. 379 ware respectively, Delaware river and bay are flanked on the west from Philadelphia to Dover by a deposit of brick-clay or loam passing into gravel below—the Philadelphia Brick Clay and Red Gravel of the former author, and the Delaware Grav- els of the latter. The deposits have been described in detail by these authors, and it will suffice to add that not only in gen- eral characters but in the less conspicuous features detectable on minute examination they are undistinguishable from their homologues in corresponding position on the Susquehanna and Potomac; the structure and composition are similar, the geo- graphic and hypsographic distribution are alike, there is equal lixiviation and ferrugination, like ravining by erosion, the same ‘extensive terracing, ete.; the only noteworthy difference being the somewhat greater altitude of the Delaware deposits, and the occasional presence of far transported northern pebbles and bowlders in their lower portion. North of Philadelphia the Delaware deposits exhibit certain noteworthy characteristics allying them with those of the upper Susquehanna. Over the gentle river-ward slopes of eastern Montgomery and bucks counties, Pennsylvania, more or less conspicuous accumulations of loam or brick clay occur up to altitudes ef 250 feet or more; and well rounded bowlders oc- casionally appear at even greater altitudes. Within 100 feet above tide the deposits are practically continuous and exten- sively terraced—e. g., there is at Trenton a sharply defined terrace 80 feet in altitude composed of homogeneous brick clay passing downward into a bowlder-bed, through which the Delaware has cut its modern gorge; and the celt-yielding Trenton gravels fill a basin lined with these older Quaternary deposits. Still farther northward the brick-clay or loam, with associated cobbles and bowlders, are found at progressively in- creasing altitudes; they occur in every inter-montane valley on the Delaware to the terminal moraine at Belvidere ; and they are found on both sides of the Lehigh from its mouth to the water-gap, the loam being largely utilized in brick manufacture at Allentown and elsewhere. The cross-section of the Delaware valley five miles below Belvidere is in all essential respects a duplicate of the Blooms- burg-Berwick cross-section of the Susquehanna shown in fig. 1: there is the same loam-lined base-level valley 200 to 300 feet above the river, with scattered quartzite bowlders up to at least 400 feet; within this valley there is excavated, through loam and subjacent rock, an outer gorge at least a mile and a half wide; this outer gorge is bottomed with well rounded and current-sorted overwash gravels from the terminal moraine; and the sharply cut inner gorge of the present river, quarter of a mile wide and 50 feet deep, has been carved in the newer Am. Jour. Sct.—TuirD SEeRrEs, Vor. XXXV, No. 209.—May, 1888 23 380 Wi J. McGee—Three Formations of gravels. To the northward the high level loam and bowlders pass beneath the terminal moraine, and the overwash gravels _ graduate into the hillocky debris of the drift-lined valley as on the Susquehanna; and as on that river too the overwash gravels rapidly diminish in size and abundance down stream, the ter- races meantime merging and decreasing in height, until both practically disappear above water level 10 miles below Bel- videre. Local accumulations of the overwash gravels occur, however, at various lower points on the river, the last and most conspicuous being at Trenton, where the later-glacial Dela- ware river opened into a broad estuary in which the vernal ice-floes dropped their debris gathered at the ice front. ~ On the Delaware, as on the Susquehanna, the two series of superficial deposits—the moraine with its derivatives and the terraced brick clay with its gravels—are perfectly distinct and widely diverse in age; and here, too, the deposition of the loam and high level eravels must have been accompanied by transformation of the Delaware river from a rapid unnaviga- ble stream abounding in cascades and rapids, to a tidal estuary miles in width within which fine silt and clay were dropped, and upon which bowlder-bearing ice-blocks floated—the land- submergence reaching fully 400 feet in the latitude of the terminal moraine. The Deposits on other Rivers.—Every considerable stream of the Middle Atlantic slope has at the fall-line a conspicuous deposit analogous to those of the Potomac, Susquehanna, and Delaware; and while the deposits vary in volume with the streams, the structure, the composition, the geographic and hypsographie relations, ete., remain constant or change slowly with latitude. The Schuylkill and Brandywine deposits merge into those of the Delaware, but in their up-stream extension are distinguishable therefrom by the abundance of local and the sparseness of northern materials; the deposits of Elk and Northeast rivers are distinguishable from those of the Delaware on the one hand and of the Susquehanna on the other by the preponderance of local materials, and at low levels by their independent terrace systems; the Patapsco deposits merge into those of the Susquehanna at Baltimore, but local pebbles in the lower member and the preponderance of local residuary debris in the upper give individuality to the Patapsco. delta, which in structure, composition, and general aspect, is undistinguishable from that of the Potomac river at Washington; the two branches of the Patuxent have beautifully terraced. deltas ex- hibiting characteristic bipartition and all of the diagnostic features of the fluvial phase of the Columbia formation ; and the Anacostia has an independent but homologous system of deposits and terraces made up predominantly of materials de- rived from the marginal portion of the Piedmont area. the Middle Atlantic Slope. 381 South of the Potomac river the deposits and terraces remain conspicuous, though their maximum altitudes diminish: Occoquan river, Acquia creek, and neighboring streams have well-marked terrace-systems built of deposits of uniform structure, though each deposit is made up of the materials traversed by the individual stream; the Rappahannock valley is fashioned into terraces miles in extent and flanked by brick clays passing into gravel and bowlder beds made up of the Piedmont rocks and well-rounded gravel derived from the adjacent Potomac beds, the whole resembling the delta of the. Potomac river so closely that a typical section in one would equally represent the other; the Taponi and the Mat have corresponding deltas which unite and flank the Mattaponi for miles, and the two Anna rivers exhibit similar deposits of greater volume merging along the Pamunkey ; the superficial deposits about the head of tide in James river are so similar to those of the Potomac that Plates VI and VII could be almost exactly duplicated there, though the area of the delta is somewhat greater and its altitude somewhat less than that of the latter river; the Ap- pomattox has its elevated delta which merges into that of the James, but is distinguished in the vicinity of Petersburg by an independent system of terraces and by the preponderance of local rocks; the Nottoway and Meherrin also exhibit well- developed deposits of the usual bipartite structure, as do the smaller streams, Rowanty, Stony, and Fontaine; and finally the Roanoke embouches from its narrow Piedmont gorge into a tidal estuary flanked by low bluffs built of or capped by the prevalent brick clay and gravel with local bowlders. The maximum altitude of the deposits, which is 500 feet on the Susquehanna and 400 feet or more on the Delaware, diminishes southward to perhaps 275 on the Schuylkill, 245 at the mouth of the Susquehanna, 145 feet (with inconspicuous deposits somewhat higher) on the Potomac, 125 feet on the Rappahan- nock, 100 feet on the James, and 75 feet on the Roanoke; and as already pointed out,* the maximum size of the bowlders in the lower member, as compared with those now transported by the rivers, diminishes from 60:1 on the Susquehanna to 20:1 on the Potomac, 10:1 on the Rappahannock, 5:1 on the James, and 2 or 8 times the present volume on the Roanoke. Recapitulation.—Briefly, the deposits along the Middle At- lantic slope rivers about their loci of transition from fluvial to estuarine condition are so closely similar that not only will the description of a typical section on one waterway apply to those of all the others, but it would in most cases be difficult to determine from the most minute examination which stream *This Journal, II, xxxiv, 219, 1887. 382 W. J. McGee—Three Formations of a particular specimen or section represents; the differences are limited to systematic variation in altitude and coarseness, to variation in volume (which is proportional to that of the streams on which the deposits occur), and to imconspicuous variation in composition resulting from the incorporation of (1) local materials on each river, and (2) rock-flour and other glacial debris on the more northerly rivers. The deposits are evidently contemporaneous and homogenetic; the structure, composition, geographic and hypsographic distribution, terrae- ing, and other features of each independently proves that it is a sub-estuarine delta formed during a brief period of land-sub- mergence and refrigeration, increasing northward; and the relations of the various deltas to the terminal moraine and other deposits prove that this period was long anterior to that of the last ice-invasion. : The Interfluvial Phase—Character and Distribution.—The fan-shaped deltas flanking the Middle Atlantic slope rivers at the fall-line attenuate down stream and toward their periphe- ries, and either disappear in feather edges along ascending slopes, or merge into a distinctive deposit by which the inter- fluvial portion of the Coastal plain is generally mantled. This deposit, unlike the complementary and more conspicuous one developed only along the rivers, is variable in composition and inconstant in structure, and has a wide range in hypsographie distribution. our leading structural types, ranging in alti- tude from 100 feet in the south to 400 feet in the north down to tide level, may be discriminated. 1. As exposed in the terraces and shore lines in the vicinity of the fall-line, the deposit consists of a heterogeneous and irregularly bedded mass of sand, gravel and bowlders fringing the terrace, and increasing in thickness from perhaps a foot or two upon the terrace plain to five, ten, or fifteen feet along the searp; the materials being predominantly local, and evidently derived largely from contiguous portions of the terrace-plain but intermingled with loam, pebbles and bowlders similar to those of neighboring deltas. Similar accumulations occasion- ally fill old ravines and other depressions in the formerly irregular surfaces now smoothed into terrace-plains. This type of the deposit is well exhibited in the scarp of an extensive terrace near Washington (in a cutting on the Falls Church road), and in the cuttings in the ‘northeastern part of the same city on Benning’s road; but such exposures are common, and those observed and noted between the Roanoke and the Delaware are numbered by scores. They frequently occur above the maximum altitude of the fluvial phase of the formation in the same latitude. 2. A second type is exhibited only in northern New Jersey the Middle Atlantic Slope. 383 and on the marginal portion of the Piedmont zone at altitudes reaching 250 feet or more. It consists of great beds of well rounded quartzite cobbles a foot or less in diameter, together with many smaller pebbles, generally imbedded in reddish loam. A representative locality is the plateau (100 to 150 feet above tide) between Harlingen and Rocky Hill and five or six miles north of Princeton, where, over an area of several square miles, well rounded quartzite cobbles cumber the fields and are heaped up along the lanes in great winrows sufficient to fence the farms and pave the roads. 3. The type of the deposit into which the deltas commonly merge is a confused and heterogeneous mass of sand, gravel, and pebbles of obscure or inconstant structure, the materials evidently derived in larger part from the sub-terrane and in smaller part from the contiguous deltas, and the thickness ranging from a foot or two to perhaps fifteen or twenty feet. In the south the materials are predominently fine, comprising sand, clay and silt interspersed with occasional pebbles up to three or four inches in diameter, with a few intercalated sheets of gravel; while in the north the deposit is predominently coarse and gravelly, especially toward the northern extremity of the Coastal plain where it has been recognized by Cook, Lewis and Chester as “Southern Drift,” “Yellow Gravel,” “ Dela- ware Gravels,” etc.; and in a general way it varies in coarse- ness and in thickness from the fall-line to the coast, the thick- ness increasing and the coarseness diminishing seaward. This is by far the most extensive type of the deposit ; it covers perhaps three-fourths of the area of the Coastal plain ; but despite its vast extent, good exposures are uncommon. Those at Ordinary Point on Sassafras river, in northern New Jersey, and on Long Island (described elsewhere by the writer, Cook and Merrill, respectively), are, however, representative of the latitudes in which and the altitudes at which they occur. 4. At low levels, especially along the coast, the deposit be- comes fine, assumes moderately regular stratification, attains considerable thickness, and yields recent fossils, This type has been described by W. B. Rogers in eastern Virginia, Tyson in peninsular Maryland, Booth and Chester in southern Dela- ware, Conrad in New Jersey and southern Maryland, Merrill on Long Island, and others in different localities, and does not require extended notice here. Summarily, the interfluvial phase of the formation consists of a mantle of either heterogeneous or definitely assorted and deposited material, largely local but partly erratic, overspread- ing the Coastal plain (except along the water way 8), from the Roanoke to the Raritan, and encroaching upon the Piedmont 384 W. SJ. MeGee—Three Formations of region in the north; this general mantle merges into the elevated deltas of the fluvial phase on the one hand, and into the modern alluvial, estuarine and marine deposits on the other ; : and it is either buried beneath or broken up and incorporated within the terminal moraine in its northward extension. Sources of Materials.—The prevailing materials of the de- posit may be roughly classed as (1) well rounded cobbles and pebbles, such as those of northern New Jersey; (2) well rounded quartz and quartzite gravel, such as overspr eads penin- sular New Jersey; (3) fine gravel and sand, clean or intermixed ~ with clay or silt, forming a matrix in which the coarser materials are imbedded, and constituting the great bulk of the deposit, particularly in the south; (4) loam, resembling that of the upper division of the fluvial phase, and exemplified by the high level red loams of northern New Jersey and southeastern Pennsylvania; and (5) clay and silt, generally stratified and limited to low altitudes. The sources of the first two of these classes are precisely, and those of the next two proximately, determinate. 1. The cobbles of northern New Jersey are in form and material identical with, and in size generally smaller in a graduating series than, the high level bowlders of the fluvial phase along the Delaware: both are identical lithologically with the axial quartzites of ‘the southeasternmost Appalachian ranges ; and both cobbles and bowlders not infrequently con- tain fossils identical with those of the quartzite ridges. The erratics, it is true, are commonly more profoundly metamor- phosed than the parent ledges; but they obviously represent the most obdurate portions of these ledges, and moreover examination shows that in many cases the metamorphism is superticial and produced by interstitial growth after the manner described by Irving, while the interior remains ‘in the same condition as the quartzites now found zn sztw. Some of these cobbles doubtless formed originally a part of the Potomac formation, and were removed from it and redeposited during the Columbia epoch; but others appear to have been derived directly from the quartzite ranges whose bases were washed by the floe-bearing Columbia waters, and whose ledges were shattered by the Columbia cold. Certainly the angular blocks now cumbering the upper mountain slopes, and the smaller and well-rounded cobbles imbedded in the Columbia formation, are but the extremes of a graduated series whose continuity can be readily traced along either the Delaware or the Lehigh. 2. Save that its average size is slightly smaller, the well- rounded gravel of peninsular New Jersey and the Maryland- Delaware peninsula is identical in all physical characters with that of the Potomac outliers skirtmg the Piedmont escarp- the Middle Atlantic Slope. 385 ment from the James to beyond the Schuylkill; there is not a fossil nor a rock-variety in one that cannot be duplicated in the other; the materials are sometimes absolutely undistin- guishable in hand-specimens or in extensive sections except by general structural features ; and in some eases the high-level gravels of the Potomac outliers may be traced continuously into the low-level gravels of the Columbia. The lower mem- ber of the Potomac formation is the great gravel source of the Middle Atlantic slope, and has furnished materials for upper Potomac, Cretaceous, Eocene, and Miocene gravel beds; but during the Columbia period of delta-deposition the waves of the ocean beat upon its unprotected outliers between the Rap- pahannock and the Raritan, and especially between the Sus- quehanna and the Delaware, and its contributions were larger than ever before. By petrography, by paleontology, by strue- tural continuity, and by physiographic relations, it is proved that the source of the mysterious gravels of the northern Coastal plain are derived from the Mesozoic gravel-heaps of the adjacent Piedmont margin. 3. In a general way the fine gravel and sand may be traced by petrographic similarity to the immediate sub-terrane and to the terranes traversed by the nearest great water-ways: and in some cases—e. g., Where they consist of redeposited Potomac arkose with little admixture of foreign matter—the exact source may be ascertained. 4. The amount of loam found in any part of the formation is roughly proportional to the proximity of deltas; and its origin is evidently the same as that of the predominant element in the upper division of the fluvial phase of the formation, 7. ¢., it is redeposited residuary debris from the Piedmont region. 5. The clays and silts appear to be made up of the finest and farthest-transported debris from rocks 2m sitw and from the coarser materials, both local and erratic. Genesis.—It is impossible to convey definite conceptions of geologic structure or topographic configuration by verbal de- seription ; and it is impracticable to prove the sub-aqueous origin of the interfinvial phase of the Columbia formation by mechani- cal reproduction of structural aspect, as in the fluvial phase ; but neither is necessary (1) since the sub-aqueous deltas of the fluvial phase graduate into and are stratigraphically continuous with the interfluvial phase, (2) since marine fossils have been found within it by a dozen eminent geologists and paleontologists (enumerated later), (8) since no other agency or agencies known to geologic science are competent to produce such de- posits, (4) since its margin is marked by unmistakable shore- lines and beaches, and (5) since every geologist who has ever investigated any considerable part of the formation, including 386 W. SJ. McGee—Three Formations of Lyell, Mather, the Rogers brothers, Tuomey, Desor, Conrad, Booth, Tyson, Kerr, Fontaine, Cook, Lewis, Chester, Merrill, Br itton, and others, “has recorded the conviction that such part at least was waterlaid. The physiographic relations of the phenomena and the area over which they prevail are such that the evidence of sub-aqueous origin is cumulative, and now that definite observations have been extended over the greater part of the area it can only be regarded as decisive ; the coarse- ness of the northern deposits as compared with the southern, and the occasional presence of evidently ice-dropped bowlders indicates that the period of submergence was one of refrigera- tion; and the limited volume of the formation indicates that the period of deposition was short. So the interfluvial deposits corroborate and extend the testi- mony of the deltas; and the phenomena conjointly record a brief period of submergence of the entire Coastal plain in the Middle Atlantic slope reaching 100 feet in the south and over 400 feet in the north, with coéval cold, long anterior to the terminal moraine period. The Terraces and Shore Lines—Every Middle Atlantic slope river embouches through a narrow gorge in the Pied- mont escarpment into a widely flaring shallow valley partly occupied by the estuarine portion of the river; and each of these valleys is notably terraced. The city of Weldon is lo- cated on a broad terrace of the Roanoke sixty feet above its tidal waters; Petersburg is built upon two or three distinct terraces flanking the Appomattox, of which one is 110 feet in altitude and many miles in extent; the higher portions of Rich- mond, including the public park, are located upon an extensive terrace overlooking James river from a height of 180 feet above tide on the north, while another terrace eighty feet in altitude has an area of at least twenty-five square miles on the south side of the river; the terraces on the Rappahannock at Freder- icksburg are as distinctive and more extensive than those of the lacustral basins of Bonneville and Lahontan, as are also those about Washington; the valleys of the Patuxent and Patapsco, of the Susquehanna, and of the Brandywine and Schuylkill, exhibit wide reaching series of terraces of progressively in- ereasing altitude; at Trenton the Delaware has cut a narrow gap in an otherwise continuous terrace of brick clay and gravel of great extent and uniformity, and through that gap the Trenton eravels have been swept; and at Metuchen, N. J., wonderfully broad terraces extend to the very base of the hillocky terminal moraine, which has evidently been pushed out upon their plains. While the best developed terraces about the mouths of the rivers form independent systems, the higher members fre- the Middle Atlantic Slope. 387 quently extend across the divides from river to river. Thus between the Roanoke and the Appomattox the highways traverse sensibly horizontal plains, only broken at long intervals by the low steep scarps of terraces, or by the narrow steep- sided. ravines incised within them, the plains being of such extent as to yet remain imperfectly drained. The same is true of the low plateau between the Appomattox and the James, and of the greater part of the country between the James and Rappahannock. North of the Rappahannock the high level terrace-plains become less conspicuous as the shore line rises from the friable clastics to the firm crystalline terranes, but considerable plains occasionally occur ; and between the Schuyl- kill and the terminal moraine beautiful terrace-plains of wide extent are carved out of the Triassic sandstones up to altitudes of nearly 200 feet. The terraces are best developed along the inland margin of the Columbia formation, but reach somewhat greater altitudes, ranging from about 100 feet in the south to more than 400 feet in New Jersey. Though most prominent along the fall-line, the terraces are not contined to it, but occur at intervals over the entire Coastal plain, their extent and perfection depending upon the mate- rials in which they are carved or from which they are built, and upon the erosion they have suffered. Thus in eastern Maryland it is possible to approximately map the western boundary of the greensands by the perfection of the terraces —the firm clays to the westward being everywhere distinctly terraced, while the more friable sands have assumed the char- acteristic undulating surface happily designated “ topographic old age” by Chamberlin. In brief, there is a practically continuous series of terraces and beach marks along the fall line from the Roanoke to the terminal moraine—a series of shore lines as distinctive and un- mistakable as those circumscribing the valleys of the extinct lakes of the Great Basin, of India, of northern Arabia, or of the partially ice-bound basins of Minnesota, Michigan, Ohio and New York, though they are generally more profoundly modified by erosion and are frequently concealed by forests. These shore lines embody an easily interpreted record of geologic vicissitude which coincides in every detail with that of the Columbia deposits. They are sometimes carved out of the sub-terrane but are generally built of the loam, sand, and gravel of which the Columbia formation consists, and are evidently coéval therewith. Now it is manifest that these terraces are water fashioned ; but they are not fluvial. There is always a vertical component in fluvial action, and the energy of the action varies with the value of this component; every alter- ation in the course of a wandering stream means change in 388 W. S. Bayley—Spotted Rocks from Minnesota. declivity, and every change in declivity means modification in competence and variation in deposits. So fluvial deposits are heterogeneous. Moreover rivers take the paths of least resist- ance and flow freely in deep channels, and in selecting their courses they avoid the higher levels and seek depressions which they continually deepen; the deeper the initial depres- sion the more rapidly is it deepened ; and thus fluvial action ever accentuates irregularity of surface. So fluvial plains are multiform. But the forces concerned in the formation of the Middle Atlantic slope terraces acted horizontally over great distances and with uniform energy for a considerable period, filling depressions, softening contours, and obliterating ‘relief, yet so gently that essential homogeneity of deposit in the hori- zontal direction and essential uniformity in surface prevails for miles. Only the undulatory and horizontally acting force of waves appears competent to produce so great expanses of uni- form surface and constant structure as are exhibited in this region. By the testimony of terraces and shore-lines the existence of inland seas and lakes of Quaternary age in many portions of the world has been proved to the satisfaction of geologists ; yet although the middle Atlantic slope terraces have been more deeply graven by erosion and reduced by weathering, they are more extensive than those of any of the extinct or shrunken Quaternary lakes in the country ; and their testimony is equally decisive. [To be continued. ] Art. XX XII.—On some peculiarly spotted Rocks from Pigeon Point, Minnesota ; by W. 8. BAaYuEy. [Published by permission of the Director of the U. 8S. Geological Survey. ] THE northeastern extremity of Minnesota is known on the charts as Pigeon Point.* This point extends in an easterly direction into Lake Superior. It is separated from Canada by the waters of Pigeon Bay and Pigeon River. Its length is about three and a half miles. Its width varies from a few hundred feet to a little less than half a mile. The greater por- tion of its mass consists of a great dyke of coarse olivine gab- brot or diabase. Associated with this is a large quantity of * The exact location of the point is T. 64 N., R. 7 E. of the 4th principal meridian, Sections 25, 26, 27, 28, 29, 30, 31 and 32. + Cf. Irving: Copper-Bearing Rocks of Lake Superior, Monograph V, U.S. G. S. Washington, 1883, p. 369 et seq. WLS. Bayley—Spotted Rocks from Minnesota. 389 bright red drusy granite, whose relations to the gabbro have not yet been satisfactorily determined. ‘'T’o the south of these eruptive rocks, on the Lake Superior side of the point, is a narrow strip of slates and quartzites, which dip to the southeast at_ an angle of 15°—20°, and are cut by numerous diabase dykes. According to Irving* these slates and quartzites belong to Hunt’s Animiké series and are Huronian in age. Upon their contact with the eruptives these fragmenta] rocks lose all traces of sedimentary origin. Under the microscope they are seen to have undergone extreme metamorphism. Whether this consists in a mere recrystallization of the material already existing in them, or in a recrystallization with the addition of new substance derived from the eruptive rocks, or in a com- plete solution of their fragments in the latter must be left for further: study to decide. The object of the present paper is to describe certain pecu- liar spots noted on the quartzites in a few localities and to dis- cuss briefly their origin. The quartzites in their unaltered forms comprise evenly bedded light gray, pinkish and black varieties. These are all very compact and hard, and have the vitreous appearance characteristic of indurated quartzites. They are cut by joint eracks running in a north and south direction and standing nearly vertical. The sides of these cracks are usually covered with little quartz crystals. Under the microscope the darker varieties are seen to consist mainly of round and angular pieces of quartz, in a groundmass of interlocking silica, which under crossed nicols is resolved into small areas optically continuous with the original grains to which they are attached.t De- composed orthoclase, colored red by minute plates of hematite and iron hydroxide, a very little plagioclase, sometimes fresh but more frequently much altered, little flakes of brown bio- tite, chlorite, and grains of magnetite and earthy iron minerals constitute the balance of the rock. In the lighter varieties the plagioclase is more abundant and the chlorite much less so. In the pinkish varieties reddened orthoclase and plagioclase make up about half of the entire rock. In certain restricted areas on the south shore of the point, notably in the western half of section 25 and in the southeast quarter of section 32, curious circular spots are developed on the surface of the quartzite. These spots vary in size from less than a quarter of an inch to over two inches in diameter. Ona weathered surface they appear as slight depressions surrounded by a raised rim of a lightish brick-red color. Their distribution * This Journal, xxxiv, 1887, p. 262. + Cf. Irving and Van Hise: Bulletin of the U.S. Geol. Survey, No. 8, Wash- ington, 1884, a 390 W. S. Bayley—Spotted Rocks from Minnesota. is veryirregular. Frequently a single spot stands alone. Some- times two or more spots are united, and when this is the case one rim encloses the group. Figure 1 represents the shape and general appearance of some CY Of of these groups as seen on € OC a smooth weathered surface. I~ 5 a When the rock bearing i) v6 such spots is broken it is observed that the bodies producing them are them- O > selves either lenticular in ‘2 shape or spherical. They possess a sugary texture and are of a pistachio green color. When moistened with hydro- chloric acid they effervesce with a slight evolution of gas. Like the circles on a weathered surface these spheroidal bodies are also surrounded by a narrow brick-red rim. The rims are here fairly well defined against the substance which they euclose, but on their outer edges gradually shade off into the body of the tock, Associated with these spotted rocks, but at a greater distance from the eruptives, are other quartzites which show no spots on a weathered surface, but which contain little concavities with diameters of about the same magnitude as those of the spots mentioned above. On a fresh fracture of these, instead of the green spheroidal bodies, are circular and oval areas, which reflect the light evenly, as from a smooth cleavage sur- face, and show a silvery luster. When treated with acids they effervesce very briskly. They are nothing more than concre- tions of calcium carbonate so often met with in the slates and sandstones of many regions.* Under the microscope the body of a specimen of one of these rocks (No. 11,461 of the collection of the Lake Superior Division U. 8. Geological Survey) is seen to be composed of an ageregate of quartz, “feldspar and green mica. The quartz is in rounded grains, which everywhere show secondary enlarge- ment. Much of the feldspar is triclinic. The green mica is slightly pleochroic and seems to have crystallized in position. A few grains of magnetite are scattered through the section, and small areas of calcite are occasionally found enclosing the other constituents. The silvery spots consist of perfectly trans- parent calcite. This encloses all the other constituents, which are the same as those found in the main portion of the section. It polarizes in large areas, although several of these are seen in a single spot. Fig. 1. About one-third actual diameters. * Ct. Tschermak: Lehrbuch der Mineralogie, Auf. II, p. 117. _W.S. Bayley—Spotted Rocks from Minnesota. 391 The rocks immediately associated with the spotted rocks in the same beds, but which themselves are free from spots, differ but slightly from the last described rock in structure. They contain, however, quite a large quantity of chlorite, which has clearly been derived from biotite on the one hand, and from feldspar on the other. Closely intermingled with this, but more particularly in the neighborhood of little calcite nests numerous irregularly shaped plates of a light green, strongly pleochroic and brightly polarizing epidote are fre- quent. In most cases however the epidote occurs in tiny rounded grains and rudely outlined crystals scattered every- where throughout the feldspathic and chloritic groundmass in which the enlarged quartzes are imbedded. ‘These little parti- cles are sometimes crossed by cleavage cracks parallel to which extinction takes place. They have a faint greenish tinge and a very high refractive index. In addition to chlorite and epi- dote the rocks of this class sometimes contain flakes of brown biotite, magnetite and calcite.- The groundmass of the spotted rocks when examined under the microscope, presents the same features as are observed in the epidote-bearing rocks just described, except that the epi- dote grains are much. less abundant and in some cases are almost entirely lacking. : The spots, on the contrary, are usually very rich in epidote. They consist of enlarged quartz grains, a little feldspar and occasionally a small quantity of chlorite, all imbedded in a mass of calcite and epidote. The amount of calcite present — varies within wide limits. It sometimes occupies nearly the entire space between the quartz, feldspar and chlorite to the almost complete exclusion of the epidote. In other cases it occurs only sparingly, while the epidote is massed in little plates, grains and crystals. Only rarely were well terminated crystals observed (No. 11,463). These average z!; of a milli- meter in length. A few forms are represented in figure 2. Although but very slightly pleochroie, the true nature of the crystals cannot be doubted. In color they are of such a very pale green tint as to be almost colorless. They possess a cleavage and an extinction parallel to their long axes, have a high indéx of re- fraction and are usually free from inclusions. They are distinguished from sahlite, which they closely re- semble, by the fact that the plane of their optical axes is at right angles to their cleavage. ? 392 W. S. Bayley—Spotted Rocks from Minnesota. Around the spots are clear zones corresponding to the raised rims, mentioned as surrounding the hollow interiors of spots on a weathered surface. ‘These zones are sometimes composed of grains and plates of epidote larger than those found in the interior of the spots, either with or without calcite. When epidote is present in the rims there is a scarcity of this min- eral in the interior of the spots. This is the rule in those rocks which contain a large amount of altered feldspar and chlorite. In these feldspar, quartz, chlorite, a little bleached biotite, little plates of hematite and grains of magnetite constitute both the interior of the spot and the body of the rock. In the spot the chlorite is better crystallized than elsewhere. The rim contains only quartz, calcite and epidote, except on its outer edge, where there is an accumulation of red oxide of iron. In those cases in which the interior of the spots con- tains a large amount of epidote, the exterior zone is compara- tively free from this mineral, consisting essentially of quartz and feldspar stained red by iron oxides. In both eases chlo- rite is absent from the rim. Although each specimen of these spotted rocks, when ex- amined under the microscope, presents features peculiar to itself, it is unnecessary to describe them all. It is sufficient to have called attention to their most striking characteristics, and to have mentioned merely those features common to the class. The incidental peculiarities due most probably to slight differ- ences in the original composition of different parts of the beds have been neglected. The occurrence of the spots in well defined beds lying be- tween those which contain no spots, would at once lead to the supposition that they owe their origin to the existence in these beds of some substance, which was absent from those contain- ing no spots. The shape of the spots and their groupings suggest coneretions. Epidote is not known to occur in such forms in fragmental rocks, while concretions of calcite are common. The existence of such calcite concretions in the unaltered rocks of Pigeon Point is clearly established in the one instance mentioned above (No. 11,461). Here we have a quartzite differing in no wise from similar quartzites occurring at a distance from the eruptive rocks, except in the possession of calcite concretions. Nearer the eruptives, whether these be granite or diabase, are other quartzites containing a little more well individualized chlorite and large quantities of epi- dote. This epidote is closely associated with calcite, the latter increasing with the decrease of the former, and the two being always bounded by the outlines common to coneretionary bodies in sedimentary rocks. As the result of a large number of studies upon limestones which have been altered in the W. S. Bayley—Spotted Rocks from Minnesota. 398 neighborhood of eruptive masses it has been found that epi- dote* is one of the most common of the new minerals pro- duced. Moreover it is known that in these cases of limestone metamorphism the eruptive rocks have added but little, if any, of their substance to the intruded rock, except perhaps silica. Their principal agency in the production of contact phenomena has been heat. The percolation of silica-bearing solutions through calcite-bearing sedimentaries was alone not sufficient to produce the crystallized epidote described above. This is evident from the existence of epidote-free calcite concretions in rocks occurring at some distance from any eruptive mass, while at the same time these rocks are typical indurated quart- zites in which all the quartz grains have been enlarged by the deposition of secondary silica around them (No. 11,461). There was no necessity for the addition to these concretions of any material from the eruptive rocks in order to change them into epidote. They already contained the elements essential to the formation of this mineral. These merely needed an oppor- tunity to arrange themselves in the form of epidote—a very stable compound under the conditions prevailing during con- tact metamorphism, as so many investigations have shown. This opportunity, it is believed, was afforded by the appear- ance of the eruptive masses. The epidotic rocks and spotted quartzites are always found in close proximity to masses of eruptive origin. They moreover contain large amounts of newly developed chlorite, a result which may likewise be ascribed to contact action. It would seem, then, that we are justified in regarding these epidotic rocks, particularly the spotted varieties, as the result of the action of the intrusive rocks, upon the sedimentary beds through which they forced their way from beneath. Where calcite was scattered in little nests through the mass of the fragmental rocks, epidote is now found in similar rela- tions to the other constituents. Where the calcite was present in spheroidal concretions enclosing quartz grains, feldspar, chlorite, etc., there now occur little spheroidal bodies con- sisting in large part of crystals of epidote. The hard envelopes around these spheroids appear to owe their power to resist weathering principally to the lack of chlorite in their composi- tion. In closing I would acknowledge my obligations to Dr. Geo. H. Williams of the Johns Hopkins University for valuable suggestions offered during the earlier portion of this study. January 19, 1888. * Cf. J. Roth: Allgemeine und chemische Geologie, Bd. i, p. 428 et seq.; and Rosenbusch: Mikroskopische Physiographie, 1885, Bd. i, p. 498. 394 ©. D. Walcott—The Taconic System of Emmons. Arr. XX XIII. —The Taconic System of Emmons, and the use of the name Taconic in Geologic nomenclature ; ‘by. Cuas. D. W axcort, of the U. 8. Geological Survey. With Plate III. (Continued from page 327.) NOMENCLATURE. I. Use of the name Taconic. II. Use of the name Cambrian. III. Classification of North American Cambrian rocks. Use of the name Taconic.—To the writer the evidence pre- sented and referred to in the preceding pages proves that the “Taconic System” was founded on errors of stratigraphy of such character and magnitude that the name Taconic has no claim upon the geologist for recognition in geologic nomenclat- ure. I endeavored to make, in 1886, an argument for the use of the name Taconic for the Middle division of the Cambrian System, but it failed in the light of later results of field work; and now I think that geologic nomenclature will be benefited by dropping the name entirely. Based on error and miscon- ception originally, and used in an erroneous manner since, it serves only to confuse the mind of the student, when applied to any formation or terrane. There are several reasons for the foregoing conclusions that perhaps it is best to here state : 1st.—The name is not applicable. The Taconic range, from which the “ Taconic System” was named, is not known to contain a fossil of the First fauna or a formation that contains one elsewhere. The “Upper Taconic” slates lie west of the range, and the “Granular Quartz” series east of it; and the range is formed of strata of the Trenton-Hudson Terrane. 2d.—The “Taconic System” was considered pre-Potsdam, on two suppositions: (@) that the Calciferous sandrock of the Lower Silurian is unconformably superjacent to the Taconic slates, on the west ; (4) that the variation of the lithologic char- acters of the Lower Taconic rocks, from the New York Lower Silurian, indicates a distinct system of rocks. We find that the unconformity (@) was based on errors of field observation, and (6), that the ‘‘ Lower Taconic” rocks are of Lower Silu- rian age, with the exception of the lower quartzite, which is Cambrian and conformably subjacent to the Lower Silurian. 3d.—The claim of priority of discovery of the Primordial fauna is invalidated by the fact that the fossils found in the Taconic slate were referred to a pre-Potsdam horizon on an erroneous interpretation of the stratigraphy and not from com- parison with a known fauna that had been stratigraphically lo- cated in any clearly defined geologic section. C. D. Walcott—The Taconic System of Emmons. 895 4th.—It is only a fortunate happening, and not a scientific induction based on accurate stratigraphic or ,paleontologic work, that any portion of the “ Taconic System” is found to be where Dr, Emmons placed it. 5th.—The application of the principles stated at the begin- ning of this paper rules out the name Taconic from geologic nomenclature. 6th.—The term Cambrian antedates Taconic for a strati- graphie system and, also, as a correctly-defined faunal defini- tion. It was stated under “ Discussion ” that Professor Dana held the opinion that the “ Lower, Taconic” was the typical “Ta- conic System,” as first defined in 1842, but as that was proven to be Lower Silurian in age, the “Taconic System” could not longer be recognized.* For a time I was inclined to disagree with this view, “but as I approach the end of this investigation I am convinced, after a full consideration of all the circum- stances, that the position taken by Professor Dana is the cor- rect one. The first published section of the “Taconic System” gives all the rocks included within it in 1842.¢ The gneiss is rep- resented on the extreme east and the ‘Taconic slate” on the extreme west and the “shales of the Champlain group ” resting unconformably on the “Taconic slate.” This section includes a// the strata of the ‘“‘ Taconic System,” as then known to Dr. Emmons, and agrees with the description, in the accom- panying text, of the rocks of the System.t Five additional sections are given on Plate XI, four of which are in the typical area and agree with the section in the text (loc. cit., p. 145, fig. 46). The latter section and the first four sections of Plate XI do not extend west of the area of Hudson slate on the line of Hoosick Falls in Rensselaer Co., N. Y. (see map). They all limit the “Taconic System” at this belt of the Hudson Terrane, and the accompanying text corrobo- rates the view expressed in the sections. A glance at the map shows that not one single outcrop of rock of the ‘“ Upper Taconic ” was included in the “ Taconic System,” as originally proposed, with the exception to be noted of Section 5, Plate XJ, and not until 1857 was it proven that any portion of the original Taconic System was older or subjacent to the horizon of the Potsdam sandstone. As is mentioned in the 1st reason given for rejecting the name Taconic, there is not a known stratum of rock in the Taconic range that is of the geologic * This Journal, IIT, vol. xxxi, pp. 241-244, 1886. + Geol. N. Y., pt. 2, p. 145, fig. 46, 1842. t Loe. cit., pp. 144, 145. Am. JouR. Sci.—THIRD SERIES, VOL. XXXV, No. 209.—May, 1888. 24 396 0. D. Walcott—The Taconie System of Emmons. age assigned to it by Dr. Emmons. In 1844 he incorporated a great series of slates and shales belonging to another geologic system by extending his sections across the western belt of the Hudson Terrane, that limited the section of 1842, and on west to the next line of outcrop of Lower Silurian rocks. This addition gave the opportunity to separate off the “ Upper Taconic” in 1856. I have shown that all his reasons for call- ing this series pre-Potsdam were based on errors of strati- graphy ; and that it was a fortunate happening that any por- tion of the “Upper Taconic” rocks occur where he placed them in his stratigraphic scheme. Even if there were no errors to vitiate Dr. Emmons’s argument for the pre-Potsdam position of the “ Upper Taconic,” that portion of his system could not retain the name “Taconic ;” for it belongs to a dif- ferent stratigraphic system from that to which the strata of the Taconic range belong and to which he gave the name ““ulacomic:? Section V, of Plate XI, represents a section of strata a few miles south of Burlington, Vt., and includes, not the “ Taconic System” of the first five sections and the text by Dr. Emmons in 1842, but strata entirely disconnected from the original Taconic, which, nineteen years later, was proven to belong in part to the “Upper Taconic.” This section is not mentioned in the text, but it is evidently considered as exhibiting the same relative geologic section as the other sections, a view that is substantiated by the name “Taconic slate” being given to the strata referred to the “Taconic System.” There is not any stratigraphic connection between the Vermont section (No. 5) and the sections in the Taconic area (see map), and until 1859 there was not any paleontologic evidence that the slates of sec- tion 5 were or were not of the same geologic age as the “Ta- conic slates” of the five other sections and the text. In 1859 the publication of the Olenellus fauna by Professor Hall, proved that Dr. Emmons was mistaken in referring the Ver- mont slates, of section 5; to his Taconic System of 1842. I do not think that we can admit as evidence in favor of the strata of the ‘“ Upper Taconic” having been described in the original work of 1842, such an erroneous identification of a section that had at the time no stratigraphic or paleontologic connection with the original Taconic System. It was not until the field work, in the fall of 1887, was con- eluded that I arrived at the above conclusions. Professor Dana reached it long before, and Dr. T.S. Hunt holds that the ‘Lower Taconic” is the typical Taconic. It matters not whether geologists agree to restrict the test of what the origi- nal Taconic was to the original Taconic of 1842 or hold that Dr. Emmons had the right to add the strata separated off into C. D. Walcott—The Taconic System of Emmons. 897 the “Upper Taconic” in 1856, the name Taconic does not ap- pear to have any place in the geologic nomenclature of to-day. The following tabulation of the successive phases of the Taconic system viewed in the light of present facts is instrue- tive. It was proposed in a letter from Professor Dana to the writer : | PHASE I, 1842. (GSiaconicg Systeme ese aeee ay sakes lace Se) True order begins. IG Stockbridge limestones 52552 ss tee Il. Lower Silurian limestone. | 5, § Magnesian slate of Graylock -.---.---- III. Hudson slate. * J ” () Gremomllane (WAM. 62 SS tees ess ose I. Cambrian. Wear lUiM OS LOn Came ner terOnRSe lays) a) pla II. Lower Silurian limestone. | 3. Magnesian slate of Taconic mountains... III. Hudson slates. | oe Sait Innes one casos Sees eee es Il. Lower Silurian limestone. (ale RAConens atom ater mats = sajna We BOLT III. Hudson slates. PHASE II, 1844. 5. a. Black slate. Fossiliferous ._-___---- J. Cambrian. b. Taconic slate as eeiibag pop Loar ca Mostly Hudson slate. GS nS — oo cask oe eee eso ewes II. Lower Silurian limestone. 3. Magnesian slates__.__---_... LeU a nicer III. Hudson slates. 2 mtockbridge limestones 2--2¥ 52222) nc: II. Lower Silurian limestone. eG ranilars quail Ziaseeses es oe Nie genial I. Cambrian. PHASE III, 1855. I. Upper Taconic. DPB IAC eS Aten ila pemners Sa) o Sere, SEL I. Cambrian. eehaconi cus ate sears a megeer nies sacra ts Sua III. Mostly Hudson slate. Il. Lower Taconic. 3e Magnesianyslateseeeeae ses 2a eee a= ib Edson’ slate: 2. Stockbridge limestone and Sparry lime- FIONN Sse Ree ha oe. SSN I ae wg II. Lower Silurian limestone, i, -Grenalleye oterigs. 0 syeeese sigs ee I. Cambrian. Use of the name Cambrian.—TVhere is no necessity for re- viewing the Silurian-Cambrian controversy. All the facts, as understood by many writers, are accessible to the student of English geologic literature. It is my opinion that the name Cambrian should be used for the system of strata characterized by the “ First Fauna.” The Cambrian System was correctly established on a strati- graphic basis in 1835, and included the same relative geologic terranes as the “Taconic System,” with the exception of going a little lower in the section containing the Primordial fauna, Like the Taconic, it included the Lower Silurian (Ordovician) System, a fact noted and corrected by Dr. Emmons, for the Cambrian, in 1842. The Cambrian section stands intact to- day, and, on faunal evidence, separates into two great divisions, the lower of which is the Cambrian System, as used by many * Made equivalent to the lower unfossiliferous part of Sedgwick’s Cambrian as known to Dr. Emmons at that time. 398 C.D. Walcott—The Taconic System of Emmons. writers for the system of strata characterized by the “ First Fauna,” and the upper the Champlain of Emmons, the Lower Silurian of Murchison, or the Ordovician of some more recent authors. CLASSIFICATION OF NortH AMERICAN CAaMBRIAN Rocks. In the classification of the fossiliferous sedimentary rocks of all countries it becomes more and more evident that the great systems—Cambrian, Silurian, Devonian, etc.—must rest on the broad zoologic characters of their included faunas and not on stratigraphic breaks between the systems, and that geologists will need to recognize the fact so well stated by Lapworth, that “we have no reliable chronological scale in geology but such as is afforded by the relative magnitude of zoological change—in other words, that the geological duration and importance of any system is in strict proportion to the comparative magnitude and distinctness of its collective fauna.”* In pursuance of the above principle I have separated the Cambrian System in North America from the Lower Silurian. In the magnitude of sedimentation and extent of the fauna it ranks with the other great geologic systems, and we cannot unite it with the Lower Silurian except from reasons that, if followed out, will unite all the systems from the Cambrian to the Quaternary. In arranging the different strata composing the Cambrian System three primary divisions are distinguished by the pre- dominence in each of a fauna that, in assemblage of genera and species, may be separated from others whenever two or more of them occur in the same stratigraphic section. This extends ~ to the identification of the relative geologic horizon by the fauna when its vertical or geographic connection with other faunas is not preserved. The three divisions of the table have been recognized to a greater or less extent in all the sections of Cambrian strata studied in North America, and all the ob- served Cambrian faunas come within their limits. The second column in the table gives local names that have been applied within certain geologic provinces, where the fauna and the sedimentation indicate a greater uniformity of conditions than existed throughout the larger areas outlined by the first three divisions. The right-hand column gives the names of local subdivisions where the conditions of sedimenta- tion and of life were still more restricted. The table is a correlation of the various sections descriked in the introduction to U. 8. Geological Survey Bulletin No. 380, and hence is tentative. It is the expression of my present knowledge and opinion. All who use it in geologic work * Geol. Mag., vol. vi, p. 3, 1879. 0. D. Walcott—The Taconic System of Emmons. 399 should refer to the data given in that Bulletin, and decide indi- vidually upon the value of the correlations made in the table. | Lower portion of the Calciferous formation of New ate York and Canada. Lower Magnesian of Wis- consin, Missouri, ete. : UPPER | Potsdam. Potsdam of New York, Canada, Wisconsin, Texas, CAMBRIAN. | Wyoming, Montana and Nevada; Tonto of Ari- Knox. | zona; Knox Shales of Tennessee, Georgia and entoe a Alabama. The Alabama section may extend down into the Middle Cambrian. Georgia. | Georgia and ‘‘Granular Quartz” formations of Ver- mont, Canada, New York and Massachusetts. MIDDLE L’Anse au | Limestones of L’Anse au Loup, Labrador. CAMBRIAN. Loup. | Lower part of Cambrian section of Hureka and | Highland Range. Nevada. Upper portion of Prospect. Big Cottonwood Cafion Cambrian section, Utah. St. John. Paradoxides beds of Braintree, Mass., St. John, Braintree. New Brunswick. St. John’s area of Newfound- LOWER Newfound- land; Lower portion of Big Cottonwood Cafion CAMBRIAN. land. Cambrian section, Utah. Uinta? (The Ocoee Uinta ? conglomerate and slates of Kast Tennessee are doubtfully included.) DeEscRIPTION OF THE Map AND SECTION. The map shows the geographic distribution of the strata re- ferred to the “Taconic System” in eastern New York and Western Vermont, Massachusetts and Connecticut. The data for it are taken from the Geological map of Vermont and New Hampshire, by Professor CH. Hitchcock, 1877 (Geol. North- ern New England); the maps published by Professor Dana, on the geology of the region studied by him in western Massa- chusetts and Connecticut, and eastern New York; and the map of southwestern Vermont, published by Professor Dana on the result of Rev. A. Wing’s field studies (Am. Jour. Sci, 3d ser., vol. xiii, 1877); and for Washington and Rensselaer Counties, N. Y., as mapped from field work done by myself in 1886-87. The line of contact of the Cambrian and pre-Cambrian rocks on the east, in Vermont, is tentative, as it is known to be in- correct in details; the data for correcting it have not been ob- tained. Certain changes in the identification of the strata, as com- pared with the older maps, have been rendered necessary by the correlations made in this paper; and the shales, in the vicinity of the limestones south of the Rensselaer county line, have not been colored, as it is yet undetermined whether they belong to the Hudson or Cambrian Terrane. The shales im- mediately beneath the limestone (8) are shown as a distinct 400 ©. D. Walcott—The Taconic System of Emmons. terrane (2) in the section but on the map they are merged with the Georgia terrane (5). The exact localities of fossils within the typical Taconic area are shown by the letter F. Many localities to the north and south are not indicated. Section.—The geologic section crosses the Taconic area on the line marked A, B, on the map, which is very near the line of the original section published by Dr. Emmons in 1847 (Geol. N. Y., pt. 1, pl. xviii, Sec. 1). On the line ©, D fossils have been found more abundantly on the eastern side, and the structure is found as in Dr. Emmons’s section of 1856. 1. Cambrian quartzite—Terrane No. 1. 2. Hydromica (Potsdam ?) shales—Terrane No. 2. . Trenton, Chazy and other limestones of the Lower Silurian —Terrane No. 3. 4, Hudson (hydromica) shales of the Taconic range and, in the Hudson valley, the Hudson terrane—Terrane No. 4. 4a. A belt of strata of the Hudson terrane, faulted in between Cambrian rocks—Terrane No. 6 of text. 5, 5a. Slates, with interbedded limestones and sandstones of the Georgia Terrane, of the Cambrian—Terrane No. 5. 6. Pre-Cambrian (Agnotozoic) or Archean rocks. a, 0, ¢, d, fault lines, known to the writer, in Washington County, N. Y. The hade of the Ball Mountain fault (@) is ap- proximately correct (see fig. 12) while that of the other faults is probably much more oblique or inclined to hori- zontal than as represented. They are drawn to show where they occur and not to indicate the hade or angle of the faults. The minor undulations, faults and displacements that occur on the east side, between 3 and the gneiss are not represented. ee) Comparing this with Dr. Emmons’s sections, we find a dif- ference in the arrangement of the strata in the eastern half. The “ Lower Taconic” embraced the strata from Terrane No. 1, on the east, to Terrane No. 3, on the west side of the Ta- conic range, and included a// the strata of the original “ Taconie System ” as known and defined by Dr. Emmons in 1842. The “Upper Taconic” included the strata of terranes Nos. 2, 4, 4a, 5, and 5a, west of the Taconic Range, which was added to the original “Taconic System” in 1844. I have not attempted to show that the quartzite contains interbedded limestones and schists in some localities, nor that the limestone series (8) is broken by interbedded schists or are- naceous beds; nor that, as at Graylock, the quartzite (1) ex- tends completely beneath the synclinal of the limestone (8) and appears on the western side. It is only the illustration of the RR. D. Salishury—Terminal Moraines in Germany. 401 general relations of the quartzite, limestone and schists to each other that is attempted. To the west of the Taconic Range the section passes down through the limestone (3) to the hydromica schists (2), and thence to the great development of slates and shales with their interbedded sparry limestones, calciferous and arenaceous strata, all of which contain more or less of the Olenellus or Middle Cambrian fauna.* No. 2 occupies the stratigraphic position of the Potsdam for- mation elsewhere; and 5 and 5a by contained fauna and strati- graphic relations, are correlated with the Granular Quartz series (1) and referred to the horizon of the Middle Cambrian, as the latter is defined in Bulletin 30, U. 8. Geological Survey, and in the table of classification (ate). Between the limestone (3) and the slates (5) there are several displacements, but none to displace the strata sufficiently to bring rocks of other formations in sight, and so break the sec- tion that the general relations of 3, 2 and 5 can be interpreted by me in a different manner from that given in the section. Arr. XXXIV.—Terminal Moraines in North Germany ; by Professor R. D. Sarissury, of Beloit, Wisconsin. Durtine the past summer some observations have been made upon the drift formations of northern Germany which may not be without interest to the students of Quaternary Geology in America. It is the writer’s expectation to continue the same line of study next season. It is due toPresident T. C. Chamberlin, who has done so much for Quaternary Geology in America, to say that the study of the drift phenomena of the above specified region was undertaken at his suggestion, and that he had forecast with surprising accuracy, the results which observation has confirmed. So far as the work has been prosecuted, attention has been mainly directed to a terminal moraine, or, more exactly, to a terminal morainic belt, which crosses Germany, and which has been traced in more or less detail from Denmark to the Rus- sian border. In the tracing of this belt, the main reliance has been upon topography, which here, as in America, affords the most reliable and the most available single criterion for the de- termination of the formation. So striking is the topography throughout the greater part of the course of the moraine in Germany, that it could not fail to * Thirty-five species in Washington County, N. Y., as known to date. (See this Journal for September, 1887). 402 BR. D. Salishury—Terminal Moraines in Germany. attract the attention of one familiar with the surface expres- sion of terminal moraines. The determination of the general course of this belt is, therefore, attended with no difficulty, and its surface deportment, taken together with other charac- teristic accompaniments, is such as to leave no possible doubt as to the genuineness of its morainic character. The other features of terminal moraines upon which, in the absence of decisive topography, reliance must be placed, are never want- ing where the topography is strongly marked. This is as true of the formation in Germany as in America, but the necessity of resorting to these less decisive characteristics as a prime means of determination, is here less frequent. In some portions of its, course, the morainic belt is single and strongly developed, and its limits sharply defined. In others it is composed of more or less distinct members, some- times weak and unobtrusive, and often assuming complex rela- tionships. The number of these constituent “belts, as they now appear is not constant. In certain meridians, four have been recognized, more or less distinctly separated "from each other, while in other parts, through the union of two or more of these members, the number is reduced to three, two or even one. No attempt will be made at this time to indicate the position of these individual belts, though through considerable portions of the course of the moraines, this might be done. Detailed study will make it possible to map these constituent belts, and to determine with some degree of precision, their relationships in time. It is to be borne in mind, therefore, that although the belt is here outlined in its entirety, and as if it were a unit, it is not to be regarded as a single moraine, or even as a belt of moraines necessarily closely connected in origin, or 7m point of tume. The belt, as here outlined, embraces a broad tract, within which morainic developments are a general—a domi- nant fact. Occasionally the belt is seriously interrupted, 1 some or all its parts by broad gaps, some of which Popes the drainage avenues of the ice-period, and some of which appear to be the beds of lakes which occupied reéntrant areas within the margin of the ice itself. In a general statement of the course of the moraine, and only a general statement is here admissible, these details cannot find ‘place. Within the belt too as here outlined, there are numerous inter-morainic tracts, which are now and then of considerable proportions. The width of the morainic belt is so great that the position of the outer and inner borders will be separately indicated. Leaving out of consideration for the moment certain subordi- nate, but very significant phenomena which will be adverted to PR. D. Salishury—Terminal Moraines in Germany. 403 later, the course of the moraine-belt, commencing at the west, is essentially as follows: Through the northern part of the province of Schleswig, it lies near the eastern coast of the peninsula, having a nearly north-and-south course. It passes through Flensburg at the head of Flensburg Fjord, and beyond this point assumes a course bearing slightly more to the east, but still nearly corre- sponding to the coast-lne. Its outermost (southwestern) border hes a little southwest of the city of Schleswig, and a few miles north of Rendsburg (province Holstein), on the Eider. Con- tinuing in the same general direction, the outer border lies a few miles north of a line connecting Rendsburg with Neu Minster. Its limit is here sharply defined, and easily recog- nized. Beyond Neu Minster it bears more to the south, and passes near Segeberg, Oldesloe and Mélln. Here it curves more to the eastward, and passes near Zarrentin, on Schall lake and near Boddin. Eastward from this point (lat. 53° 35’, lon. 28° 45°), the belt is, for some distance, very complex and discontinuous, at least in its outer portions. The individual moraines are widely separated, and the area here outlined is therefore proportionally wide, and embraces much territory which is not morainic. The general course of the belt however is continuous in a direction south of east. Its southern border lies south of Pritzwalk and Wittstock (province Brandenburg), in the vicinity of Neu Ruppin, and a little north of Eberswalde (lat. 52° 45’, lon. 31° 30’). In the longitude of Pritzwalk and Wittstock, the main developments are much farther north, although reasonably strong moraines lie as here indicated. East of this point the moraines reach their southernmost extension. For some dis- tance east of Eberswalde their course is easterly and then bears to the northward. The main developments lie north of a line passing near Soldin, Friedeberg, Woldenberg, south of Neu Stettin, and north of Konitz, from which point the outer border follows a generally northeasterly course to the longitude of Danzig. The northern border of the moraine-belt to this point, com- mencing with Schleswig, follows approximately the coast line as far as Rostock. Its width is therefore very great. Last of Rostock, the northern border lies north of Teterow, near Neu Brandenburg, a little south of Pasewalk and north of Stettin. Eastward from Stettin, its course is more or less direct to a point a few miles north of Danzig. From the meridian of Danzig a moraine of huge propor- tions swings to the southeast, thus exhibiting on German soil, the phenomenon of morainic looping so abundantly repre- sented in the United States. The southern border of this ° 404 R. D. Salisbury—Terminal Moraines in Germany. eastern loop lies south of Stargard, near Jablonowo and Man- towo (lat. 53° 20’, lon. 37° 20’). Here its course becomes more easterly, and finally north of east, passing near Ortelsburg (lat. 53° 30’, lon. 38° 30’), and thence extending in a wenerally direct course to Lyck, near the Russian frontier (lat. 53° 45, lon. 40°). The corresponding northern border lies north of Riesenberg (province Ost Preussen), a little north of Morungen, near Bischofistem and Rastenburg (lat. 54°, lon. 39°). In cases in which the individual members of the morainic series are not united with each other, they are sometimes dis- tinctly traceable individually, and sometimes so connected by cross ranges, as to form a sort of morainic complex or network. The separate ranges are individually strong at certain places and weak at others. They are sometimes all strong on a given meridian, sometimes all weak, and again some are massive while others are feeble. The moraines or the morainic belt, therefore, considered as a unit, constitutes a very different topo- graphic feature in different regions, and is generally much more conspicuous when the moraines are united, than when they are separated. Apart from the relief produced by the formation itself, the country traversed by the moraine is generally level. It is therefore often a conspicuous feature, rising 200 feet or 300 feet, and even 400 feet above the surrounding country. With a given elevation it is Conspicuous or unobtrusive, according as its rise from the bordering lowlands is prompt or gradual. It is sometimes so pr ominent as to have received the local appel- lation of mountain range, and numerous points are, in this level country, designated mountains. It is possible that in such cases the total elevation is not always entirely due to drift accumulation, although no evidence to the contrary is at hand. Throughout most of its course, the belt constitutes so promi- nent a relief feature as to have been a potent factor in deter- mining drainage. The topography of the moraine distinguished from the moraine as a topographic feature—is exceedingly varied. For the most part it 1s characterized by the knob ‘and basin topog- raphy which is so generally char acteristic of terminal moraines in similar situations. This topography finds expressions in all degrees of strength. Even when of the sag and swell, or knob and basin. type, there may be, with a given altitudinal variation, wide variations of topography limited on the one hand by the nature of the mater ial, which limits the maximum gradient of slopes, and on the other by the width of the mo- raine, which fixes the minor limit possible within the same. These extremes, as well as all gradations between them, find place in the moraine in gestion. The topography is now PR. D. Salisbury— Terminal Moraines in Germany. 405 rough, now gentle, according as the elevations and depressions have steep or gentle slopes. Throughout wide stretches of the moraine, the altitudinal variations, within narrow areal limits are fully 100 feet. Not infrequently, isolated basins, “ kettles,” no more than 10 or 12 rods in diameter, have a depth of 50 feet below the lowest points of their borders, while pointed knolls rise 100 feet or more in their immediate vicinity. Com- monly the topography is less strongly marked, the undulations assuming gentler, flowing contours, with variations much less than those indicated. . More broadly considered, the relief of the moraine is not con- fined to so narrow limits. At many points there are variations of 200 feet or 250.feet within the moraine. These however are not commonly so closely associated as are those of smaller proportions, so that even with the greater range, the surface may appear less rough. Occasionally the moraine surface is wanting in knolls and basins, but this is rarely the case for any considerable distance. The topography and the complexity of the moraine, together with its great width, afford abundant opportunity for the for- mation of lakes, which are accordingly an almost constant con- comitant of the moraine. Their number is exceedingly great. So characteristic are they, and so nearly restricted to the mo- raine, that a tracing of the lake belt would be almost identical with a tracing of the moraine itself. In constitution, the moraine presents all the diversities common to such formations. Sand, gravel and clay predomi- nate each in turn, and the ratio between coarse and fine mate- rial is an ever-varying one. In general, it. may be said that the moraine is predominantly sandy, at least superficially, and that the proportion of stony material is great. Scarcely less characteristic than the features of the moraine itself, are certain deposits of drift, widely associated with it. Among these are the extensive plains of sand and gravel, par- ticularly the former, which skirt the outer face of the moraine. In scores of localities which have fallen under notice, approach to the moraine from the south is over a wide belt of sand, which has a distinct though gradual upward incline toward the moraine. The material of these border plains becomes coarser as the moraine is neared, and contains bowlderets and even bowlders in the immediate vicinity of the range. It is to be observed that the moraine lies far north of the southern limit of drift, just as the main moraines of America he, throughout the larger part of their course, far north of the southern drift limit. In all these characteristics, viz: in its composition from sev- eral members, in its variety of development, in its topographic 406 R. D. Salishury—Terminal Moraines in Germany. relations, in its topography, in its constitution, in its associated deposits, and in its wide separation from the outermost drift limit, this morainic belt corresponds to the extensive morainic¢ belt of America which extends from Dakota to the Atlantic Ocean. That the one formation corresponds to the other does not admit of doubt. In all essential characteristics they are identical in character. What may be their relations in time remains to be determined. It is not improbable that the outer and inner members of this series, where widely separated geographically, are also somewhat widely separated in time. The former frequently show unmistakable signs of greater age. Where the geograph- ical separation does not obtain, this difference is also wanting. This relationship would be easily explained by supposing that, where the range is single, the margin of the ice was as far advanced at the time of the formation of the subsequent mo- raines (or at least at the time of the last), as at the time of the formation of the first, and that, where the moraine is two-fold or-more, the ice failed at a corresponding number of moraine- forming periods, to reach its earlier position. Analogous rela- tionships were long since recognized in America. It may be fitting to mention a few localities where the moraine may be seen in strongly typical development. Such are (1) in province Holstein, the region about (especially north of) Eutin ; (2) province Mecklenburg north of Crivitz and be- tween Butow and Kropelin ; (3) province Brandenburg, south of Reckatel, between Strassen and Birenbusch, south of Fiirstenberg and north of Eberswalde, and between Pyritz and Soldin ; (4) province Posen, east of Locknitz, and at numer- ous points to the south, and especially about Falkenburg, and between Lompelburg and Birwalde. This is one of the best localities ; (5) province West Preussen, east of Biitow; (6) province Ost Preussen, between Horn and Windikin. The drift-covered area south of the indicated belt is not alto- gether without moraines, and in this respect also the German and American fields are similar. Furthermore, in Germany as in America, these outer developments are less continuous, partly because of subsequent erosion and partly because of their originally weaker and more discontinuous character. Detailed work will doubtless make it possible to show the con- nections of these local (as they now appear) fragments, some of which have but a limited development, while others may be traced for considerable distances. Without mentioning more isolated occurrences of this kind, reference may be made to certain morainic phenomena south of Berlin, and which, though not consecutively traced, appear to constitute for some distance a traceable, though quite unob- CO. Barus— Viscosity of Gases at high temperatures. 407 trusive belt. At several points both east and west there are fragments of moraines of undoubted character. These outer occurrences are significant, but their full meaning will only be understood when detailed work shall have shown their relationships. It is not impossible that a chain of such isolated formations may be found to be so situated with reference to each other, as to indicate an outer mo- raine of greater age than the northern group. It is possible that some of the accumulations there included, belong rather with these outer fragments, in time of origin, though not widely separated geographically from the later formations to the north. In this case, the variation in the position of the ice-front at different epochs must have been great. The failure to bring the drift formations of the continent of Europe into closer correspondence with those of our own country, is to be attributed, in part at least, to the absence of a common basis of study. The terminal moraines are unques- tionably the most conspicuous, and by means of their topog- raphy the most easily recognized of the drift formations. They are therefore especially adapted to serve as common centers of study, and with this one common phase of the drift formations, which may be in some sense a standard of compari- son the work of geologists on opposite sides of the water may, more readily than heretofore be correlated, and such cor- relation cannot fail to facilitate the solution of the many yet unsolved problems in glacial geology. Heidelberg, Nov. 15, 1887. Art. XXXV.—Wote on the Viscosity of Gases at High Tem- peratures and on the Pyrometric use of the principle of Viscosity ; by Cart Barus.* By passing gases under known conditions through capillary tubes of platinum, kept at measured temperatures between 5° and 1400°, I have found a series of data for the relation be- * The forthcoming Bulletin of the U. S. Geological Survey to which the present note refers, is a first contribution to-a research on the physical coustants of rocks, the experiments of which are to follow a general plan devised by Mr. Clarence King. The Bulletin in question is restricted to methods of high temperature measurement and will be in six parts, of which the first is a brief historical intro- duction. Chapter I of the work discusses experiments which Dr. William Hal- lock and I made in New Haven with a very large high temperature apparatus. In Chapter II (which with the following chapters is my contribution) I investigate apparatus and methods for the practical calibration of electrical pyrometers by aid of fixed thermal datas In Chapter III I discuss certain pyrometric qualities of the alloys of platinum generically, and the data lead to curious electrical results. In Chapter IV I describe methods for the calibration of electrical pyrometers 408 ©. Barus— Viscosity of Gases at high temperatures. tween viscosity and temperature of which the following little table is a good exhibit. Air and hydrogen are the gases chosen. In the table 6’, 7’, €’’, respectively denote the temperature, the viscosity and the coéfficient of external slip of the gas, ft” the radius of the capillary tube at 6”; and 7, ¢, &, have the corresponding signification at 0° C. The measurements were made absolutely. The time of efflux (¢) for a known volume of gas V,=50° nearly, varied in round numbers from t—60%° at) 02 C) to. ¢=— 23508") at 12009 for, air andistnom t= 85" at 0° C. to ¢=9008"* at 6” =1000° for hydrogen. in these experiments is about 0:0079™. The capillary platinum tubes were used in fascicles of two, side by side, and wound together in form of a nearly compact helix, at the internal and external surfaces of which temperature was measured. From 5 /I the absolute values of 7’: (+45), the quotients in the third column of the table are computed, which quotients in propor- tion as ¢” approaches zero reduce to 7’’:7. With this value I have compared (1+a4 aye where ¢=0-003665. This compari- ZA | | n yy He +4607 /R”” : 2 O | Ta | VO a 1+4¢/R Avi (Balbo wXOXGV a) yeeros eee eb Gbien| 2-083. 27113 —-030 592 | 27117 2°158 -~-041 995 2°693 2-785 —°092 1216 3147 3-099 +048 INTE (CUTS NOLO UUD) gege o e | 442 1:991 1-900 +091 569 2.149 2°119 ~+ 030 | 982 2-711 2-766 —055 STON OMe gS: Oi 3-092 +122 Hydrogen (Table XXVI) ___.-- | 961 | 2772 2-734 +038 12 eros5ed 3-095 +°486* Hydrogen (Table XXVII) __--- | 418 1-935 1-858 +077 512 2-098 - 2-023 +:075 | 1520 9-113 2-036 +077 he Sis) 2-760 2-721 +:039 * Platinum pervious to hydrogen. (notably the thermo-element) by direct comparison with the air-thermometer. I have given the porcelain bulb a re-entrant form, the bottom folding inward in such a way as to form a narrow cylindrical tube, the closed end of which is at the center of figure of the bulb. Into this central tube the junction of the thermo- couple to be calibrated is inserted. To further insure identity in the environments of the two pyrometers to be compared, the air thermometer bulb is snugly surrounded by a spherical muffle revolving around a horizontal axis. This muffle is in its turn surrounded by the walls of a nearly spherical furnace, the burners of which are set something like a force-couple and blow into the furnace a cyclone of flame revolving around the vertical. Chapter V concludes with a full experi- mental discussion of the subject set forth in the above text. C. Barus— Viscosity of Gases at high temperatures. 409 son is made in the fourth column and the residual errors inserted in the final column. The data given are typical values. ¢€ symbolizes Helmholtz’s “ Gleitungs-coefficient.” From the table it follows that for the range of temperatures within which I have observed the mean increase of gaseous viscosity takes place proportionally to the two-thirds power of absolute temperature. Interpreted by aid of the well-known Clausius-Maxwell relations, the results of the table may be stated succinctly thus: The mean free path of the molecule of a perfect gas varies directly as the sixth root of its absolute temperature. I had hoped to find that at temperatures suff- ciently high the mean free path would be independent of tem- perature, a law to be regarded as a criterion of a perfect gas and for which the experiments of E. Wiedemann when used to interpret the low-temperature results of O. E. Meyer, Puluj, Warburg, Obermayer, and particularly the admirable researches of Holman* seemed to contain suggestive evidence. But after applying many devices for the removal of. errors, I found that my original results were not essentially changed. Accepting the law of sixth roots as indicating perfect gaseity (i. e. the non-occurrence of ephemeral mechanically cohering molecular aggregates) it appears that the linear magnitude, mean free path, is proportional to the cube root. of the velocity of the mean square,—a singularly suggestive result. The chief discrepancy of my work is this, that the tempera- ture measured externally is not identical with the temperature at which transpiration actually occurs. Taking the transpira- tion data alone they show a surprising degree of accordance even above 1300°. If [6’’] be the temperature computed from transpiration data under assumption of the above law, I found in successive measurements, for instance : | Q”’ | [07] | @”’ | [0] 6” | [0’7] | 6/77 [07] | 436°) 450°|| 568°} 575°)/ 975°) 971°|| 1210°) 1245° 446 | 459 || 570| 577 || 981 | 972 || 1210 | 1247 455 | 469 || 575 | 581 || 990 | 982 || 1209 | 1245 If the law governing the thermal variations of the viscosity of a gas were rigorously known, Poiseuille-Meyer’s equation applied to transpiration data would enable us to measure tem- * After a careful consideration of his own results and those of all earlier ob- servers, Mr. Holman has discarded exponential relations altogether. For my own part, I believe that at the present stage of research a conservative policy is the wiser. In chemistry the hypothesis of residual affinity is fast gaining ground. Hence before final decision can be made, it will be necessary to have exhausted data for an interval of temperature (say 500° to 1000°) within which the ephem- eral molecular aggregates in question may reasonably be assumed to be absent. Discussion must be reserved for the Bulletin. 410 | Scientific Intelligence. perature absolutely, over a wider thermal range and with a degree of precision and convenience unapproached by any other known method. The present method lends itself easily for the study of disso- ciation phenomena in gases. I hope to be able to show that in the case of imbedded capillaries, the method may be used for the high temperature study of vapor tensions and phenomena near the critical temperature. From such points of view I am justified in believing that the favorable character of my experi- ments introduces a new instrument of pyro chemic research ; an instrument which in addition to the special work to which it may be applied, always subserves the purpose of a pyrometer, and which is particularly available for the coérdination of values within a field of high temperature where absolute data © are either isolated or wanting. Laboratory U. 8. G. 8., Washington, D. C. SiC LENDER TLC UNE LG Nein I. CHEMISTRY AND PHYSICS. 1. On the Boiling-point and molecular formula of Stannous chloride.—Biitz and Vicror Meyer have determined the boiling point of stannous chloride, the temperatures being estimated by the air thermometer. The first series of experiments gave the value 604°5°, the second series 607°7°; the mean being 606°1°. Since this substance is easily procured and is non-volatile, it may serve a useful purpose for vapor density determinations, for which we now have sulphur, boiling at 448° and phosphorus sulphide ~ boiling at 518°. Experiments on the vapor density of stannous chloride show that this constant lessens very slowly with rise of temperature. But they do not confirm the formula Sn,Cl,, origin- ally given by V. and C. Meyer. The results obtained are con- siderably greater tham the formula SnCl, requires, but the authors have not obtained a constant value corresponding to the doubled » formula. The details of the method will be given shortly.—Ber. Berl. Chem. Ges., xxi, 22, Jan. 1888. G. F. B. 2. On the oceurrence of Germanium in Huxenite.—Krtss has discovered the existence of germanium in the acid oxides obtained from euxenite. The mixed oxides were boiled with hydrogen chloride to extract the iron, washed and digested for eight days with ammonium sulphide in a closed vessel. Though all sulphides soluble in ammonium sulphide must have been thus taken up, analysis showed no arsenic, antimony, tin, molybdenum, tungsten, etc. in the solution ; and yet on evaporation and ignition, the solution left a fixed white residue, soluble in ammonium sulphide. The white sulphide obtained by Winkler’s method mixed with sulphur, was heated in a current of carbon dioxide and left a Chemistry and Physics. 411 crystalline mass of dark red sulphide showing a metallic luster. In a current of hydrogen, the sulphide yielded pure germanium having all the properties of the metal obtained from argyrodite. The amount present in euxenite is about one-tenth of one per cent. —Ber. Berl. Chem. Ges., xxi, 131, Jan., 1888. G. F. B. 3. On the Double Acetate of calcium and copper.—Rtpor¥Fr has prepared and analyzed anew the large quadratic crystals de- scribed first by Brewster. They were prepared by dissolving 25 grams copper acetate and 66 grams calcium acetate in 350 c¢.c. of water, moderately heated. On cooling the crystals separated. Upen analysis they gave the formula CaCu(C,H,O,),. (H,O),; and not (H,O), as determined by Ettling.— Ber. Berl. Chem. Ges., xxi, 279, Feb. 1888. G. F. B. 4, Ueber die Reaktionsgeschwindigkeit zwischen islandischem Doppelspat und einigen Sduren.—A recent number of that excel- lent new journal, the Zeitschrift fiir physkalische Chemie (vol. ii, p- 13), contains an interesting article by W. Sprine on the rapidity with which Iceland Spar is attacked by certain acids, in continu- ation of an earlier article in which marble was the substance in- vestigated. The surfaces exposed to the acid were the cleavage planes, and also planes cut parallel and perpendicular to the vertical axis. At a temperature of 15° it was found that the surfaces parallel to the axis dissolved with sensibly the same velocity as the cleavage planes, but this equality disappeared as the temperature rose and at 35° and 55° the reaction was 1°23, 1°28 times more rapid. In the case of the surfaces normal to the axis at 15° the rapidity of solution was greater but did not in- erease so rapidly with increase of temperature. In taking the ratio of the velocity of solution for the vertical and transverse surfaces at the different temperatures the number 1°14 is obtained ‘as the mean, which, it is interesting to note, is not far from the relation of the two refractive indices to each other (viz: 1°115). In other words the author establishes a relation between chemical activity and optical elasticity. 5. The Integral Weight of Water; T. Sterry Hunt.—In a paper on Chemical Integration published in this Journal for August, 1887, and reprinted in the Chemical News, Sept. 23d and 30th, it was said that in comparing the densities of liquid and solid bodies with those of known gaseous species , such as water- vapor and carbon dioxyd, “ or in the last analysis with the density of the hydrogen unit, . . . we get the specific gravity of these bodies, the dyad integer of hydrogen at 0° and 760™" (H,=2:0) being unity.” Subsequently, in a paper on Integral Weights in Chemistry, in the Z., &. and D. Philosophical Magazine for October, 1887, it was stated that a litre of hydrogen gas ‘at 0° and 760™™ being assumed as the unit of volume for all species, the weight of a litre of any other vapor or gas at the standard temperature and pressure is its integral weight. In like manner, the integral weight of a liquid species is the weight of the same volume at its boiling point under a pressure of 760™™. . . . The AM. JOUR. ScI.—THIRD SERIES.—VOL. XX XV, No. 209.—May, 1888. 25 412 Scientific Intelligence. weights thus obtained for equal volumes of the various liquid and solid species are evidently the specific gravities of these species ; that of hydrogen at the standard temperature and pressure being unity (H,=2'0). They are at the same time the integral weights of the species compared.” Notwithstanding this clear statement in both papers that it is hydrogen at 0° and 760™™ which is to serve as the unit of specific gravity alike for gaseous, liquid and solid species, the reader will find in these papers, and also in the first edition of the author’s New Basis for Chemistry (1887), an error in the subsequent calculation. The problem having been approached from the comparison of the weights of equal volumes of liquid water at 0° and 100°, and of water-vapor at 100° and 760™", by an inadvertence (until now unperceived) the weights alike of hydrogen gas and of water-vapor at the latter tempera- ture were substituted for their weights at 0° and 760™™ ; thus lead- ing to a grave error in the figure given for the integral weight of - liquid water, and of bodies for which it serves as the unit of spe- cific gravity, and making it equal 29244. In fact, however, tak- ing as the unit of weight that of the litre of hydrogen gas at standard temperature and pressure (0° and 760™™”) and comparing it with that of liquid water at 100° (its temperature of formation at 760™"), when a litre of it weighs 958-78 grams, we have: 0:0896 3 958°78 $3 2 3 x = 21400°3. This value is thus alike the specific gravity of the liquid on the hydrogen basis and its integral weight, which, if we take H,O= 17:96, corresponds very closely to 1192(H,O)=21408; ice being probably 1094(H,O), calcite, 584(CCaO,) and aragonite, 630 (CCaO,). While the writer regrets this error in calculation, made in direct contradiction to the principles laid down by him in both of the papers cited, it will be seen that its correction in no way affects their argument, which he hopes to develop further at an early day. Washington, D. C., February 22, 1888. 6. Absorption Spectra.—The relation of absorption spectra to the various physical constants of the substances which afford the spectra has not been fully made out. ER. SrencER’s experiments conduct him to the conclusion that the absorption of light by various substances depends primarily upon the size of the physical molecule. Changes in the state of aggregation, or changes pro- duced by different media in which a substance is dissolved pro- duce absorption spectra of different character only when the state of the physical molecule is also altered. The author dis- cusses, from this point of view, the law of Kundt connecting the index of refraction and the dispersive power of a medium in which a substance is dissolved with the displacement of absorp- tion bands toward the red end of the spectrum. Vogel’s re- searches upon the absorption of dyes in the solid state, obtained by staining gelatine films, and their absorption in the liquid state is also adduced as an evidence of the truth of the author’s Chemistry and Physics. Ds AS hypothesis that the physical molecule in concentrated solutions is more complicated than in diluted solutions.—Ann. der Physik und Chemie, No. 4, 1888, p. 577. Sig 7. Wave-length of the two red lines of potassium.—A determi- nation by M. H. Deslandres gives for the stronger line 766-30, for the weaker 769°63. As a measure of comparison the wave- length of D, was taken as 588°89.—Compte Rendus, March 12, 1888. Sele 8. Explosion of gases.—A. von CATTINGEN and A. von GERNET have repeated the work of Bunsen, Berthelot and_ Vieille, and also that of Mallard and Le Chatelier upon this subject making use however of instantaneous photography to study the phenomena. A rotating mirror was employed with a metallic pointer to which an electrical spark passed when the mirror was in the right position to reflect an image of the eudiometer tube, in -which the explosion took place, into a photographic camera. The same spark served to explode the gases. The most sensitive Beernaert plate gave no trace of an image. No results could be obtained by staining the plates with cyanine or with azaline. Kastman’s negative film paper, however, gave a faint image. The authors were compelled to sprinkle certain powders in the eudiometer tube. Chloride of copper gave the best results. Plates of the phases of the explosions accompany the paper. The experiments show that the explosion of hydrogen is not accom- panied by light. The resulting high temperature, however, pro- duces a disintegration of the glass of the eudiometer tube and produces a certain illumination. Three species of wave motion are observed : first, a fundamental wave, which is entitled Ber- thelot’s wave; second, more or less parallel secondary waves; third, polygonal waves of smaller amplitude. The photographic image of the electric spark which was received upon the same plate as that of the explosion, enabled the authors to estimate the velocity of the explosion. The result obtained, 2800 meters per second, is-of the same order of. magnitude as that obtained by Berthelot. The authors agree, in the main, with Berthelot’s con- clusions, differing only in reference to the beginning and the end of the explosion. They explain the secondary waves on Bunsen’s hypothesis of the reflex action of waves due to successive ex- plosions produced by the electrical spark. They, therefore, term these Bunsen’s waves.—Ann. der Physik und Chemie, No. 4, 1888, pp. 586-609. Jey Te 9. Dust particles in the Atmosphere.—Joun AITKIN in an arti- cle read to the Royal Society of Edinburgh, gives a method of estimating the number of these particles in the air. The method is based upon the hypothesis that in a receiver filled with super-saturated air when there are few dust particles present the fog particles are large and are seen to fall like rain inside the receiver. A small glass receiver was connected with an air pump and with a cotton wool filter. Inside the receiver was placed a small stage with a silvered mirror ruled with fine lines which 414 Scientific Intelligence. served to enumerate the fine drops. The latter, under a micro- scope, appear brilliant, upon a dark suface. The following are some of the results obtained by this method : Source of the air. Number per ¢. ¢. QOutsideyairyralmin oe ee ee DPSS NE RAS DRT 32,000 Qutsid evans fair yes Ss a eee era PL fe oa ere a 130,000 TRO MN hs ee ee SD Sh AT Dy HR Rag A De 1,860,000 VO OMAN TT CAT COUT oleh LY aia are eae Eaten 5,420,000 Bumsgen’ Blame) says See eee eevee Pe Ine abs ea 30,000,000 — Nature, March 1, 1888, p. 428. Tole 10. Magnesium and Zinc.—Hirn has investigated the electro- positive character of magnesium with the view of replacing zine in certain batteries. In the Daniell cell its E. M. F. is 2 volts; in a Grove 2°9 volts; in a Leclanché, 2:2 volts, and in a bichro- mate-cell, it gives as much as 3 volts. The local action, however, is considerable and its constancy uncertain.— Nature, March 22, 1888, p. 497. J. T. 11. Gravity.—In a discussion upon gravitation at a meeting of the Physical Society of Berlin, Helmholtz explained his concep- tion of the action of gravitation. He considers gravitation as being the law of nature, established by experience, that every body, when, in the neighborhood of another body is subject to an acceleration which is proportional to its mass and diminishes in the ratio of the inverse square of the distance between them. Such a law of nature as this, established as it is on the basis of experience, is on the whole not unsatisfactory.— Nature, March 8, 1888, p. 455. J. T. IJ. GroLoGy AND MINERALOGY. 1. Geology: Chemical, Physical and Stratigraphical; by JosEPH Prestwicu. In two vols. Vol. II, pp. 606. 8vo, Strate- graphical and Physical. Oxford, 1888. (Clarendon Press.)— The first volume of Prof. Prestwich’s valuable work was issued in 1886. This second volume commences with the oldest forma- tions, and closes with the Quaternary. Its first chapter gives a very convenient table of the geological series of Kngland with their equivalents in the different countries of Europe, and follows this with a corresponding table of the rocks of India, with an enumeration of their prominent genera of fossils; and the same for North America, Australia, New Zealand and South Africa. The author makes the Cambrian end with the Tremadoe slates, and divides the Silurian (or the remainder of it) into Upper and Lower. The volume is full in its accounts of the several forma- tions and their distribution in Great Britain and other countries, and in illustrating figures; and its plates of fossils are particu- larly fine. A handsome folded plate represents “the probable extent of land covered by ice and snow during the Glacial period, their extent now and the present boundaries of floating ice,” and its importance is doubled by being also a good bathymetric map of the oceans from recent data. An excellent colored geological Geology and Mi ineralogy. 415 map of Europe and Great Britain, folded and on cloth, makes a frontispiece to the volume and gives great value to the work. The map is by Wm. Topley, F.G.S., and J. G. Goodchild, F.G.S. It is the only map of the kind in any treatise on geology in the English language. 2. On the level-of-no-strain and mountain making.—The me- moir by Mr. Davison and Prof. Darwin on the contraction-theory of mountain-making was noticed in the last number of this Journal. The same subject has been further discussed by the Rev. O. Fisher and Mr. T. Mellard Reade (Phil. Mag. for January and March.) All of these authors agree in the existence of the level- of-no-strain in the earth, first announced by Mr. Reade, and their estimates of its depth do not vary very widely, all agreeing that it must be within a few miles (2 to 5) of the surface. As regards the amount of crumpling of strata on this basis Mr. Darwin (as noted before) makes it small and yet not entirely insignificant (228,000 sq. miles in 10 million years). Mr. Fisher’s conclusions upon the supposition of a temperature of solidification of re- spectively 7000° and 4000° are contained in the following table : Temperature of solidification. 000° 4000° Depth of level of greatest cooling_______- 54 miles 31 miles Depth’ of level of no stram____.2-._ 22 = 2 miles 0-7 miles Temperature of level of no strain__--__--- 358° BF, 1240 He Mean height of elevations ______.______-- 19 feet 2 feet Total contraction of radius __.-__._.--_- 6 miles 2 miles Mr. Reade discusses some of the geological consequences of the level-of-no-strain and concludes that it is “ plain to demonstration that the lateral pressure that forced up the mountains could not reside in a shell of compression only 5 miles thick having a zero strain in the under side.” 3. Geology of Rhode Island; Franklin Society Report. 130 pp., 8vo., 1887. Providence, R. L—This report is largely bibliographic, but is very full in notes that review well what is known on the geology of the State and show who have been the observers. They also make it apparent that no thorough study of the geology of the State has been undertaken. The State con- tains the coal formation among metamorphic rocks, and this alone makes it one of the three or four best centres to start from for the study of New England geology. 4. Annual Report for 1886 of the Geological Survey of Pennsylvania. %&vo.—This part of the Report of 1886 contains Part I, on the Oil and Gas Region, by J. F. Carll; a chapter on the Chemical composition of Natural Gas, by F. C, Phillips, and a Bibliography of Petroleum. 5. Annuaire Géologique universel, Revue de Géologie et Paléontologie ; dirigée par Dr. L. Carez and H. Douvillé, avec le concours de nombreux Géologues Frangais et étrangers; pub- lié par Le. Dr. Dagincourt. TomelIII. Paris, 1887.—The former volumes of this Aunual contained, besides lists and abstracts of geological papers of the year, a catalogue of geologists of differ- ent countries, with their places of residence. The present is con- 416 Scientific Intelligence. fined wholly to the former purpose, and in it 777 pages are devoted to the Geology and 235 to the Paleontology of 1886. It isa work that geologists, whatever their special department, will find very useful if not indispensable. 6. The Geological Record for 1879. An account of works on Geology, Mineralogy, and Paleontology published during the year with supplements for 1874-78. Edited by W. WuiraKER and W. H. Datron. 418 pp. 8vo, London, 1887, (Taylor and Francis.)—This comprehensive volume, like its predecessors in scope, will be thoroughly welcome although it is somewhat late in appearing. For the future it is announced that the editorship has passed into the hands of Mr. Topley and the work is to be brought up to date by publishing the titles only of papers from 1880-87. ‘The portion from 1880-1884 is finished and in great part printed, making two volumes. That for 1885-87 is in hand though not yet in type. Subscribers will be quite ready to re- spond to the suggestion of the editor-in-chief, that the dclay should be pardoned in view of the fact that the board of workers labor without pecuniary return. 7. A Manual of the Geology of India. Part {1V: Mineralogy (mainly non-economic), by F. R. Matier. 179 pp. 8vo, with 4 plates. Calcutta and London, (Triibner & Co.) 1887.—The economic side of the mineralogy of India has already been dis- cussed in Part III of this work by Mr. V. Ball. The scientific treatment of the same subject has now been taken up by Mr. F. R. Mallet, and this important contribution to mineralogical literature is the result. It is a subject about which our knowledge has been in the past vague and scanty, and although much re- mains to be done in the way of investigating the mineral treasures of India, this complete and accurate presentation of what is now known about them is of great value. 8. Brief notes on recently described minerals,—ARSENIOPLEITE. —Oceurs in reddish brown cleavable masses forming small veins or nodules with rhodonite and hausmannite in a crystalline lime- stone from the Sjé mine, Gryhyttan, Sweden. It is shown optically (Bertrand) to be uniaxial and negative, probably rhom- bohedral. Analysis gave: AseQs SbeO; MnO Fe.0; PbO CaO MgO _ H.0 Cl 44°98 one 28°25 3°68 - 4°48 S11 3°10 5°67 Tips == OPA This is corrected to give Mn,O, 7°80, MnO, 21:25, H,O 4°54, final sum 97°94. It is closely related to the large group of manganese arseniates from Sweden.—Z. J. Jgelstrém in Bull. Soc. Min., vol. xi, 39, 1888. BaRKEVIKITE, CaLciorHoRITE, MELANOCERITE, NORDENSKIOLD- INE, RosEenBuscuite.—In a preliminary paper giving an outline of results obtained in a study of the augite- and eleolite-syenite veins of southern Norway, Brégger has briefly described several new species and given new facts about many others, as lavenite, gibbsite, homilite, natrolite, leucophanite, meliphanite, ete. Geology and Mineralogy. 417 Barkevikite is a hornblende mineral near arfvedsonite, but dis- tinct from that in optical characters. Calciothorite is a hydrous mineral consisting of thorium and calcium silicate and probably (like thorite, orangite, eucrasite, frejalite) an alteration product of an original thorium silicate near zircon in form and composi- tion (ThSiO). Melanocerite is a complex silicate of the cerium metals, yttrium and calcinm, with other substances in small amount including 3:19 p. c. B,O,; it is found in tabular rhombohedral crystals of a dark brown color. Nordenskidldine is a mineral having the re- markable composition CaO.SnO,.B,O,. It occurs in tabular crystals belonging to the rhombohedral system. Color sulphur yellow. Hardness = 5°5-6; sp. gravity = 4:20. Rosenbuschite is a silicate of calcium and sodium with zirconium, titanium and also lanthanum in small amount. It occurs in orange-gray mono- clinic crystals near wollastonite and pectolite in angle, and is characterized as a zirconium-pectolite. Hardness = 5-6; sp. gravity, 3°30.—W. C. Brégger in Geol. F6r. Forh., vol. ix 947, 1887. : Barysit.—A new lead silicate from the Harstig mine, Pajs- berg, Sweden. It occurs in iron ore with calcite, yellow garnet, tephroite and galena. Crystallization hexagonal with basal cleav- age. Color white. Hardness = 3; sp. gravity, 6°11-6°55. Anal- ysis gave: SiO» PbO MnO FeO CaO MgO ign. 16°98 77°84 3°49 0°16 0-41 0°58 0-66 = 10012 This corresponds to 3PbO. 2Si0O,.—A. Sjogren and Lundstrém in Gifu. Vet.-Akad. Forh., xiv, 7, 1888. Be onesireE (Belonesia), CryPHroLitE (Crifiolite)—Two species described by A. Scacchi in a memoir upon a fragment of an old yoicanic rock enveloped in the Vesuvian lava of 1872. Belone- site occurs in minute acicular crystals referred to the tetragonal system; they are white and transparent. Qualitative tests lead to the conclusion that in composition it is a molybdate of magne- sium, MgO. MoO,,. . Cryphiolite occurs in small tabular monoclinic crystals covered and concealed (as the name suggests) by apatite. The color is honey-yellow; sp. gravity = 2°674. An analysis gave: P20; 48°91 MgO 33°58 CaO 14°60 Loss 2°91 = 100 The presence of fluorine is suggested and the possible amount estimated as 6°93 p. ¢., which brings the mineral near wagnerite in composition. — Mem. Accad. Napoli, Ti Nioge5: BremMentire.—Occurs in stellate acgregations with foliated structure, resembling pyrophyllite. Friable. Sp. gravity, 2°981. Color pale grayish yellow. An analysis yielded: SiO. MnO FeO ZnO MgO H.0 39°00 42°12 [3°75] 2°86 3° 83 8:44 = 100 This corresponds approximately to 2(H,,Mn)O.S8i0,; the water goes off above 200°. Occurs embedded in calcite at Franklin 418 Scientific Intelligence, Furnace, N. J. Named after Mr. C. 8S. Bement, of Philadelphia. —G. A. Konig in Proc. Acad. Nat. Sci., Philad., 1887, 311. DIHYDRO-THENARDITE.—A sodium sulphate -containing two molecules of water. It forms a thin bed on the shores of Lake Gori, Tiflis, Russia, and crystallizes in the monoclinic system.— Markownikow in Ber. Chem. Ges., 1887, 546 (J. Russ. phys. ch., Ges.). FIEDLERITE, LAURIONITE.—Two related minerals found in the old lead slags of Laurion, Greece, and produced by the action of the sea-water upon them during the past 2,000 years. Laurionite occurs in white prismatic crystals (orthorhombic) not far from mendipite in angle. Hardness, =3°5. Composition, Pb(OH),. PbCl,; an analysis by Bodewig yielding : Pb) 79:38 » Oerilig Oy ies H.O 3°68 = 100 Fiedlerite is related in composition, but no analysis has been given. It occurs in minute tabular monoclinic crystals, in part twins.— G. vom Rath in Sitzungsber. Nied. Ges. Bonn, June 6, 1887; Kéchlin in Ann. Mus. Wien, vol. 2, 185, 1887. LavuBANITE.—A zeolite resembling stilbite from the basalt near Lauban, Silesia. Occurs in fine fibrous radiated aggregates, sometimes spherical, of a snow-white color. Hardness, 4°5—-5; sp. gravity = 2°23. Analysis gave: SiO, 47°84, Al,O; 16°14, FeO 056, CaO 16:17, MgO 1°35, H.O 17:08=99:76 This corresponds to 2CaSiO,+ Al,(SiO,),+6H,O, which is not far from laumontite.—. Traube in Jahrb. Méin., 1887, vol. ii, 64. MARTINITE.—Occurs as a pseudomorph having the form of gypsum in the guano on the island Curagoa. In white or yellow- ish aggregates of colorless microscopic rhombohedrons. Sp. gravity, 2°894. Analysis gave: PeOs 46% CaO 46:'78 H.O 4°52 Organic 0°75 Insol. 0:2 0=99:°92 The formula suggested is 2Ca,(PO,),+4CaHPO,+H,O.—J. ZH. Kloos, Jahrb. Min., 1888, vol. i, 41 ref. Meratoncuipitr.—A mineral from the St. Bernhard mine near Hausach in Baden. It is essentially a variety of marcasite, agree- ing with it in form and characterized by the presence of 2°7 p. ¢. of arsenic with some nickel and lead, thus approximating closely to Breithaupt’s lonchidite—Sandberger in Uist. Zettschr. Berg- HTitt., xxxv, 1887. 9. Note on Xanthitane; by L. G. Eakins (communicated.)— Through the kindness of Mr. Wm. Earl Hidden, Prof. Clarke has lately received some fine specimens of Xanthitane, first described by C. U. Shepard, this Journal, 1856, vol. xxii, p. 96, which were turned over to me for examination. The material is from Green river, Henderson Co., N. C., and is undoubtedly an alteration product of sphene—following the form very closely. It is light yellow, friable and mixed with impurities which cannot be re- moved, preventing the determination of whether or not it is a definite mineral, but it is interesting from the fact that it appar- ently represents a clay with the silica replaced by titemic oxide. Botany and Zoology. 419 Specific gravity 2°941 at 24°. The air dried material loses 6°02 per cent of water at 100°. The following analysis is on material dried at 100°. Sid, TiO, Al,O; FeO; CaO MgQ P,0; 4H:0 1°76). 61:54 17:59 446 0°90 tr. 417 9°92==100°34 Laboratory, U. 8. Geol. Survey, Washington, D. C. Ill. Botany And Zoouoey. 1. Recent contributions to our knowledge of the vegetable cell. (Second paper, continued from page 344.)—Lorw and Boxorny distinguish between active and passive albumin in vegetable cells. The former is characterized by its great chemical instability, and especially by its property of reducing silver solutions even when they are very dilute: the latter, on the other hand, is relatively stable and is not readily changed or oxidized. ‘These distinctions have been pointed out by the authors in various communications, more recently in a treatise on certain relations of protoplasm. According to them, active albumin, in combination with water, forms all living protoplasts, and, at the death of the cell, passes over into “common” or passive albumin. The authors (Bot. Zeit., Dec. 30, 1887) announce that they have detected active albumin also in cell-sap in many species of Spirogyra. From its solution in cell-sap it is precipitated whenever a dilute solution of ammo- nic carbonate is allowed to act on the cells. A granular precipi- tate appears not only in the plasma-membrane where the granules are confined within or are attached to the membrane, but in the cell-sap as well, the latter granules settling, after a time, to the lower part of the cell. Zhese granules do not occur in either the membrane or the cell-sap if the cell has been previously killed by pressure, cutting, or by chemical means. It is interesting to compare these statements with those made by Charles Darwin and others. The views of Mr. Darwin are well known by readers of his Insectivorous Plants (see page 39), and need not be further alluded to here. Pfeffer explains the appearance of aggregation in a different way: he regards the pre- cipitate as consisting of tannate of albumin, which forms on account of the neutralization of the cell-sap by means of the am- monic carbonate. Pfeffer calls attention to the fact that the pre- cipitate re-dissolves when an organic acid, for instance, citric, is - added, and falls again when the sap becomes again alkaline. He has shown that the precipitation is effected by the addition of a tenth per cent solution of ammonic carbonate, and that re-solution occurs when a two-hundredth of one per cent solution of citric acid is employed. Loew and Bokorky state, however, that the cell-sap of Spirogyra is not acid in reaction, and that it contains no free acid. Therefore, according to them, Pfeffer’s explanation of the phenomena is not satisfactory. The so-called ‘“ aggrega- tion” is, as Francis Darwin and others have pointed out, a com- mon occurrence in many cells. It appears to demand further investigation. 420 Scientific Intelligence. It is a familiar fact that the crystalline forms of calcium oxa- late which occur in plants are referable to two crystalline types: (1) tetragonal or quadratic, when they have six equivalents of water; (2) monoclinic or clinorhombic, when they have two equivalents of water. Soucbay and Lenssen attributed the differ- ence to difference in the rate of crystallization, the first type resulting from rapid precipitation, the latter from a slower reac- tion. That the two types can occur in the same liquid is proved by a simple experiment suggested by Kny: ona glass slide is placed a drop of gelatin with a crystal of oxalic acid on one edge, at the opposite edge of the drop is placed a fragment of calcium chlorid. The two substances soon begin to form at their point or line of contact a white precipitate, first of octahedra, and later of a few monoclinic crystals intermingled with them. Haushofer has stated that the character of the mother liquor exerts a con- trolling influence on the shape of the crystals and their content of water; according to him the tetragonal crystals are formed from dilute neutral or alkaline calcium solutions at the ordinary tem- perature of the room. The other type is produced when there is a slight excess of oxalic acid or when the temperature is much higher. At this point Kny has undertaken a re-investigation of the subject (Ber. Deutsch. Bot. Gesellschaft, 8, 1887). He con- cludes that the relative concentration of the solutions in question hes a great, even if not controlling, influence in determining the form of the crystals. In the course of his experiments he made some interesting observations regarding the inclusion of coloring matters in the crystalline structure. Certain aniline and other coal-tar dyes tinged some of the crystals while other dyes were without any effect. Thus in the dialyzer, crystals of the mono- clinic type were tinged by eosin while the octahedra remained colorless; on the other hand, by aniline-blue both were distinctly colored. But in both cases the larger crystals remained without color. Fuchsin failed to color any of the crystals. G. L. G. 2. Garden and Forest. A weekly Journal of Horticulture and Arboriculture, conducted by Professor C.S8. Sareent, of Harvard University. It is pleasant to note that this periodical fully meets the expectations which were formed when the announcement of its publication was first made. Aside from matters of general and public interest, like the subjects of forest preservation, the care of plants, and the like, each number thus far has been en- riched by a description of some plant of botanical (and often hor- ticultural) interest, by Dr. Sereno Watson. These articles by Dr. Watson have been illustrated by Mr. Faxon’s excellent draw- ings. The journal promises to be a substantial addition to the list of scientific periodicals, while, at the same time, it preserves to a large degree elements of general popularity. G. L. G. 3. BrstiotHeca Zootocica.—The first number* of this im- * Bibliotheca Zoologica—Original-Abhandlungen aus dem Gesammtgebiete der Zoologie. Herausgegeben von Dr. Rud. Leuckart in Leipzig und Dr. Carl Chun in Konigsberg. Heft 1, Die Pelagische Thierwelt in grésseren Meerestiefen und ihre Beziehungen zu der Oberflachenfauna. Geschildert von Prof. Dr. Carl Chun in Konigsberg. Mit 5 Tafeln. Botany and Zoology. 491 portant zoological periodical is published. It is edited by Pro- fessors Leuckart and Chun and they propose to devote this new serial to more elaborate monographs than can from their size or the number of their illustrations easily find a place in zoological periodicals. The Bibliotheca Zoologica will hold in zoology very much the same place which Paleontographica and similar publi- cations hold in paleontology. The first number contains a most interesting monograph on the existence of a pelagic fauna at great depth and its relation to the surface pelagic fauna. Dr. Chun was engaged upon a monograph of so-called deep-sea Siphonophore’ collected by Chierchia during the voyage of the “Vettor Pisani.” Though collected on the sounding line they were labelled with the utmost precision as living below 1000 meters. Chun who was also preparing a monograph of the Mediterranean Siphonophores came to the conclusion that the collection of Chierchia supported the views of Studer that peculiar Siphonophores formed an important part of a pelagic deep-sea fauna. Under the auspices of the Zoological Station at Naples he carried on most successful deep-sea tow. net experiments from August to October, 1866. Unfortunately this expedition, interesting as its results are, does little toward settling the sub- jects under discussion because neither the distance from shore nor the depths investigated were great enough to eliminate the disturbing effects of close proximity to land; as it was near the continental slope, on the very edge of which Dr. Chun trawled with the tow net. The results are further vitiated from the fact that they have been carried on in a closed sea where the conditions of temperature are strikingly different from those of the Atlantic, and where at a depth of about 500 fathoms we find already the lowest temperatures of the deepest part of the Medi- terranean. The minimum seasonal differences of temperature between that and the surface cannot be contrasted to oceanic conditions. Dr. Chun made use for his investigations of an ingerious self- closing tow net invented by Captain Palumbo of the “ Vettor Pisani.” It may be closed at any given point by means of a pro- pellor working in a rectangular frame attached to the tow net on the same principle as the propellor for upsetting the Negretti Zambra deep-sea thermometer and the Sigsbee water bottle. The little steamer “ Johannes Miiller” of the Naples Zoological Station made an excursion to the Ponza Islands as well as expe- ditions to the Gulf of Salerno, to Ischia and Ventotene. The contents of the deep-sea tow nets used by the Challenger could not be assigned to any definite depth as the nets were not closed either on the descent or the ascent. Neither can the method adopted on the “Blake” of collecting at intermediate depths by means of the Sigsbee collecting cylinder be considered decisive. It had not been tried long enough or frequently enough at great depths (it was not carried beyond 150 fathoms) to decide the depth to which the surface pelagic fauna might sink or to 422 Scientific Intelligence. prove the existence of an intermediate deep-sea fauna in the depths between the surface fauna and the deep-sea fauna. From the depth of 1300 meters Dr..Chun brought up a large pelagic fauna. Small Craspedote Medusz, Ctenophores, Dyphiz, Tomopteride, Sagitte, Alciopide and numberless Copepods, Stylocheire, larve of Decapods, Appendiculariz, Pteropods and small transparent Cephalopods. Dr. Chun assumes that where he found this mass of Invertebrates there were no currents and that so rich a booty brought up by a hap-hazard cast of the net indi- cates a wonderful richness of the deep-sea pelagic fauna, espe- cially when we remember that surface pelagic fishing is only suc- cessiul in the wake of tide currents, calm streaks and the like. But there is nothing to show that so close in shore there is not a more or less active ‘interchange of the fauna from the shore slopes to that of the greater depths. Should the observations of Dr. Chun be repeated off shore in the deep water of oceanic basins and the existence of this deep-sea pelagic fauna proved beyond a doubt, it will help to explain the manner in which the deep- sea fauna obtains its food; nor will it be necessary to suppose, as he seems inclined to do, that these deep-sea animals are wholly dependent on the broth concocted. at the surface and passing down in a ceaseless rain upon the bottom. Surely no one who has trawled and dredged in the deep-sea can have failed to note the large number of free-swimming animals such as Crustacea, Cephalopods, Annelids and fishes of which only an_occasional specimen could be caught by the slow moving dredge or trawl, while a faster trawl brought up the more nimble deep-sea types. It seems to us that the results of Chun merely prove that in a close sea, near shore, even at considerable depth there is a great mixture of true deep-sea types and surface pelagic animals which sink at certain times far beyond the limits usually assigned to them. Certainly no one who has engaged in deep-sea work has ever supposed that there were not at the bottom or near the bottom free-swimming animals which occasionally found their way to the surface while many of the so-called surface pelagic types have been proved by deep-sea expeditions to be the young of abyssal species. Chun has however clearly proved that many embryonic stages of surface pelagic animals are only found at considerable depths. Deep-sea fishing with a properly closing net promises to be a material help to embryological investigations. Chun looks upon the slight changes of temperature as the impor- tant factors in determining the periodic rising and sinking of the surface pelagic fauna. He thinks the great increase of tempera- ture at the surface compels surface pelagic animals to seek cooler depths. While this is undoubtedly true for some groups it does not hold good for the larger number and we are more inclined to consider the condition of the surface, whether calm or rtfiled by waves and winds, as a more powerful influence. Thus while there is always a richer pelagic fauna to be collected at night it is only on calm nights that a good harvest will be obtained. Yet Botany and- Zoology. 423 in all my experience of surface collecting I have never met with such prodigious masses of surface pelagic animals as on the hot- test days of our dredging expeditions. When the sea happened to be smooth as glass under a blazing tropical sun it seemed as if the water was nearly solid as far as the eye could reach with countless surface animals of all sorts. It is true that such re- markable collections were only seen in the track of the Gulf Stream when at a distance from shore, or when we were in the track of currents due to the influence of neighboring islands or conti- nents, We have a considerable number of deep-sea sedentary types which have an extraordinary bathymetrical range. There is no reason therefore why pelagic animals which are more or less help- less and drift at the mercy of the waves and winds and currents, should not be able to flourish under similar extremes of pr essure and temperature. The more so as the majority belong to groups of Invertebrates, on which the effects of pressure would be far less perceptible. The tow-net trawling of Murray in some of the deeper lochs of the western part of Scotland indicates that the range of this deep-sea pelagic fauna does not extend far from the bottom, although specimens of nearly all the species occasion- ally find their way to the surface. There is nothing to show that the more active deep-sea Crustacea, Fishes, Cephalopods, Ptero- pods, Annelids, Acalephs, Polyps, Rhizopods have not a con- siderable range and may pass rapidly either vertically or near the bottom through layers of water of very considerable differ- ences of temperature and pressure. That this movement takes place through all intermediate layers of water near the shores within moderate depths seems conclusively proved by Chun’s investigations. That it takes place far from the continental slopes in the oceanic areas is altogether another question. Chun has also come to the conclusion that the surface pelagic fauna does not extend to any great depth, but he has undoubtedly shown that within a short distance from the shore there are a large number of deep-sea pelagic animals living within a moderate range from the bottom, and that they occasionally come to the surface. These deep-sea pelagic: types become mixed with the surface pelagic fauna much as many of the abyssal types which have a great bathymetrical range are dredged within the hundred- fathom line or near it, and constitute a part of our shallow-water fauna. We must remember that nearly all of the Radiolarians which Chun mentions as having been taken with the tow net at a depth of 300 fathoms have also been collected at the surface. The species enumerated of Tomopteris of the Phronimide are more common in deeper water than at the surface. The same is true of Stylo- cheiron, of the species of Spirialis, and of the two species of Cepha- lopods. But there are several species of large Appendiculariz, which have thus far escaped the surface tow net of all the natu- ralists who have explored the Bay of Naples. Chun seems to 424 Miscellaneous Intelligence. have demonstrated for surface pelagic animals a far greater bathymetrical range than they were known to have, and one which, perhaps, corresponds to the wide bathymetrical range of many so-called deep-sea types which extend from the greatest depths at which animals have been dredged almost to the regions of the littoral belt. An interesting chapter on the “ Dissogonie” of Ctenophores concludes this capital memoir. Chun has suggested the term Dissogonie to indicate the peculiar reproduction and development of embryo Ctenophore. He has observed that the Cydippe form of Bolina, after the degeneration of the genital organs (which are fully developed soon after leaving the ege envelope), is developed into the Bolina form. This monograph i is illustrated by five ex- cellent plates from the pencil of Dr. Chun. One of the plates gives a sketch of the deep-sea tow net, as well as of the photo- graphic apparatus used by Dr. Chun. A, AG, 6. Report on the Annelids, of the Dredging Expedition. of the U. S. Coast Survey Steamer “Blake ;” by EK. Huuers. 336 pp., 4to, with 60 plates.—Memoirs of the Mus. Comp. Zool. vol. XV. Cambridge, 1887.—An admirable volume. Some of the plates are colored; all engraved in the best style of the art. TV. MISCELLANEOUS SCIENTIFIC INTELLIGENCE. 1. National Academy of Sciences.—The following is a list of the papers entered to be read at the April meeting of the Academy in Washington: J. EK. OLIVER: The Rotation of the Sun. T. Srerry Hunt: ‘The Foundations of Chemistry. T. C. MENDENHALL: Onan Improved Form of Quadrant Electrometer, with Remarks upon its use. E. D. CopE: On the Vertebrate Fauna of the Puerco Series. On the Audi- tory Bones of the Batrachia. ORMOND Stone: The Orbit of Hyperion. B. K. Emerson: Map of Connecticut River Region in Massachusetts. A. Hyatt: Parallel Series in the Evolution of Cephalopoda. Evolution of Cephalopoda in the Fauna of the Lias. L. F. Warp: The Evidence of the Fossil Plants as to the Age of the Potomac Formation. 8. P. LANGLEY: Vision and Energy. H. A. RowLanp: Report of Progress in Spectrum Photography. Note on the Spectrum of Carbon and its Existence in the Sun. H. P. BowprircH: Reinforcement and Inhibition. A. GraHam BELL: On Apparent Elasticity produced in an Apparatus by the Pressure of the Atmosphere; and the Bearing of the Phenomenon upon the Hypothesis of Potential Energy. H. A. Newton: The Orbits of Aerolites. EK. C. Pickering: A Large Photographie Telescope. W. T. Sep@wick and G. R. Tucker: A New Method for the Biological Exam- ination of Air; with a description of an Aerobioscope. Wo.cort Gipps and Hospart Amory Hare: Preliminary Notice of the Object, Methods and Results of a Systematic Study of the Action of Definitely Related Chemical Compounds upon Animals. TRA REMSEN: On the Constitution of the so-called Double Halogen Salts. Studies on the Rate of Decomposition of the Bromides of the Saturated Alcohol Radicals. Miscellaneous Intelligence. 425 THEO. GILL: The Characteristics of the Order and Sub-orders of Fishes. F. W. Putnam: The Serpent Mound and its Surroundings. C. V. Ritry: The Systematic Relations of Platypsyllus as determined by the Larva. C. H. F. Peters: On the Position of the Nova of 1572, as determined by Tycho Brahe. J. S. NewBeRRY: Some Notes on the Laramie Group. On the Structure and Relations of Placoderm Fishes. At the meeting the Draper Astronomical Medal was presented to Professor E. C. Pickering, of Cambridge, and the Lawrence Smith Medal, for original work upon the subject of Meteorites, to Professor H. A. Newton, of New Haven. The American Anthropologist, published under the auspices of the Anthropologi- eal Society of Washington, vol. i, No. 1, January, 1888, 96 pp. 8vo. Washing- ton, D. C., 1888.—This new Quarterly Journal, which has all the commendation it needs in the fact of its being the continuation of the Transactions of the An- thropological Society of Washington, comprises in its editorial Committee: Prof. J. Howarp Gorr, Mr. THomas Hampson, Mr. H. W. HensHAw, Prof. O. T. Mason, Dr. WASHINGTON Marraews, S. V. ProupFrit and Col. F. A. SEELY. It desires to extend the range of its contributions and of the usefulness of the Washington Society. The present number contains papers by Dr. J. C. WELLING on the Law of Malthus; Col. SkELy on the development of time-keeping in Greece and Rome; Dr. FRANK Baker, anthropological notes on the human hand; and Dr. D. G. BRINTON, on the Chane-abai (four-language) tribe and dialect of Chiapas. Other papers are to appear on the nephrite question, by Dr. A. B. Meyer of Dresden; on the subject ‘‘ From barbarism to civilization,” by Major POWELL; on Discontinuities in Nature’s methods, by H. H. Barus of the U. 8. Patent Office. The subscription price of the Journal is three dollars a year. Communications should be addressed to Mr. Thomas Hampson, Washington, D. C. OBITUARY. Oscar Harcer, whose death was announced in the December number, was born in Oxford, ’‘Conn., January 12, 1843. From his father, a farmer and land surveyor, he inherited great phy- sical endurance, remarkable mathematical talents and the salient points of his strong character. By almost unaided exertions he prepared himself for college, and, entering Yale, maintained himself during the four years of undergraduate study by teach- ing and mathematical work, and was graduated with high stand- ing in the Class of 1868. During his college course he developed great mathematical capacity and ever after took special delight in abstruse mathematical work, often resorting to it for recreation. It is probable that the bent of his mind was mathematical but, while a boy, he had studied botany and become familiar with the native plants about his home, although his time was so occupied with farm labor during the proper time for botanizing that he commenced the study of grasses and sedges in winter, collecting and identifying many species from the hay stored in barns. His success in botany undoubtedly led him to turn his attention to other departments of natural history, and after graduation from college he abandoned the mathematical career open to him and began the study of zoology with Professor Verrill. In his 426 Miscellaneous Intelligence. zoological studies he at once showed special aptitude for original work and had begun important investigations when, in 1870, he accepted the position of Assistant in Paleontology under Pro- fessor Marsh, which he held uninterruptedly until his death. Although the greater part of his time and energy was given to work in vertebrate paleontology, he continued his investiga- tions in invertebrate zoology as long as his health permitted and published papers on myriapods, a fossil arachnid, isopods, and, jointly with the present writer, a report on a dredging expedition to the region of St. George’s Banks. His last and most important published works are a report on the Marine Isopoda of New England and the adjacent waters, and on the Isopoda of the Blake dredgings on the eastern coast of the United States. The former, his only completed work, is a systematic and accurate monograph, one of the most important contributions to our knowledge of the Isopoda, and will long remain a standard authority and a manual for the study of that group on our coast. These publications establish his reputation as a zoologist, but his best work and highest attainments were in the department of vertebrate paleontology. Remarkable logical powers, an unbiased mind, and years of accurate observation, had given him a truly wonderful knowledge of vertebrate osteology. Under his hand the broken and d'sarranged bones of an unknown carpus or tarsus seemed to fall into their proper places by magic. But his knowl- edge was not one of details alone; he had a truly philosophical grasp of the bearing of facts on evolution and classification ; and only the few who knew his attainments can appreciate how much paleontological science would have been advanced had he been able to publish his observations and conclusions. He was not a scientific specialist only, but took a deep and practical in- terest in politics and other questions of the day, and his peculiar- ly open mind, wholly untrammeled by bias or preconception, gave his views and arguments on any subject originality and value. Mr. Harger never enjoyed robust health, and in 1879 he was attacked by a cardiac trouble which increased from year to year. Though knowing that his life was despaired of by his physicians and friends, he never spoke of his illness but, with silent courage and indomitable will, worked on cheerfully, attending to his regular duties until prostrated by cerebral hemorrhage a week be- fore his death. In 1875 he married Miss Jessie Craig of New Haven, who, in the highest sense, was his helpful and sympathizing com- panion. Only those can fully appreciate his loss whose privi- lege it was to belong to the little circle enjoying his every day companionship and who feel that they are better for the example of his pure and inflexibly truthful life. SA nish Professor Jutes-Emite Piancuon, of Montpellier, died April Ist, at the age of 65 years. A. E. FUOTE, M. D., iT | No. 1223 BELMONT AVENUE, |i eee Perotskite, Magnet CoveArk. - PHILADELPHIA, PA. Twin Crystal Zircon. : ———— Amazon Store, Pike’s Peak, Col. |= Copies of Naturalist’s Leisure Hour, 32 paSc>> Please state in what given ireq. onjappiica: Department of Science rs i) ill hh ili, ly tion. If stamp is en- hee ‘ you are specially in- closed, the subscriber’s edition, on heavy paper, terested. s=S os is sent. A.E.FOOTE. > Scientific and Medical Books, Minerals,-< Largest Stock of Scientific Books in America. Largest Stock of Minerals in the World. ? ee Smoky Quartz. | Pike’s Peak, Col. * £ FOOTE. Quart WY Ye Magnet Cove Ark. rvstal Mts. (8) CONTENTS. Art. XXX.—The Absolute Wave-length of Light ; by Louis Bei. Partly oe ee ee ee XXXI.—Three Formations. of the Middle Atlantic Slope; by W. J. McGrr. (With Plates VI and VII) -------- XXXII.—On some peculiarly spotted Rocks from Pigeon Point, Minnesota> by WS: BAvinw 2225 eee XXXIII.—The Taconic System of Emmons, and the use of the name Taconic in Geologic nomenclature ; by CHAS. DE WALCOPE 2 398 Jor Sa Se Se XXX1V.—Terminal Moraines in North Germany; by Pro- fessor. Ri: Das ALISBURY 22 S220 5.5 Yee St = ee XXXV.—Note on the Viscosity of Gases at High Tempera- 388 394 401 tures and on the Pyrometric use of the principle of Vis- cosity; by Cary Barus -------- ele oe 407 SCIENTIFIC INTELLIGENCE. Chemistry and Physics—Boiling-point and molecular formula of Stannous chloride, Bintz and VicToR MEYER: Occurrence of Germanium in HKuxenite, KRUss, 410.—Double Acetate of calcium and copper, RUDORFF: Ueber die Reaktions- geschwindigkeit zwischen islandischem Doppelspat und einigen Sauren, W. Serine: Integral Weight of Water, T. 8S. Hunt, 411.—Absorption Spectra, FR. STENGER. 412.—Wave-length of the two red lines of potassium: Explosion of gases, A. von (HTTINGEN and A. yon GERNET: Dust particles in the Atmos- phere, JOHN AITKIN, 413.—Magnesium and Zinc, Hirn: Gravity, 414. Geology and Mineralogy—Geology: Chemical, Physical and Stratigraphical, J. . PReEsTWwicH, 414.—Level-of-no-strain and mountain making: Geology of Rhode Island ; Franklin Society Report: Annual Report for 1886 of the Geological Survey of Pennsylvania: Annuaire Géologique universel, Revue de Géologie et Paléontologie, 415.—The Geological Record for 1879, W. Wurraker and Ww. H. Darron: Manual of the Geology of India, Part IV, Mineralogy, F. R. Matter: Brief notes on recently described minerals, 416. —Note on Xanthitane, L. G. Haxnys, 418. Botany and Zoology—Recent contributions to our knowledge of the vegetable cell, Loew and Boxorky, 419.—Garden and Forest, C. 8S. SARGENT: Bibliotheca Zoologica, 420. —Report on the Annelids, of the Dredging Expedition of the U. S. Coast Survey Steamer ‘ Blake,” EH. EHLERS, 424. Miscellaneous Scientific Intelligence—National Academy of Sciences, 424. Obituary—OscaAR HARGER, 425.—JULES-EMILE PLANCHON, 426. I a ae i eT i at ee Ou i Mat Sa a JOURNAL OF SCIENCE. ERE aA INES Es 1 A RAE Gets leee GUN ae: pier , RY : 4 1 Chas. D. Walcott, U. S. Geological Survey. Meno 20 Vou XxXxV JUNE, 1888. Established by BENJAMIN SILLIMAN in 1818. ee THE AMERICAN EDITORS JAMES D. anp EDWARD 8S. DANA. ASSOCIATE EDITORS = Proressors JOSIAH P. COOKE, GEORGE L. GOODALE AnD JOHN TROWBRIDGE, or Camsripen, Proressors H. A. NEWTON anp A. E. VERRIUL, or New Haven, Proressor GEORGE F. BARKER, or PuitapEerruta. THIRD SERIES, VOL. XXXV.—[WHOLE NUMBER, OXXXV.] No. 210—JUNE, 1888. WITH PLATES VI AND VII. NEW HAVEN CONN.: J. D. & HE. 8. DANA. 1888. TUTTLE, MOREHOUSE & TAYLOR, PRINTERS, 371 STATE STREET. EAD LET ET EE RIEY ET EE A Ok PEE EE POO Ge Te ER RES SET DTT TEAS Published monthly. Six dollars per year (postage prepaid). $6.40 to foreign sub- seribers of countries in the Postal Union. Remittances should be made either by money orders, registered letters, or bank checks. GEORGE L. ENGLISH & CO, DEALERS IN MINERALS. Send for Catalogue. Free to any Address. Recent Additions to our Steck Remarkably Modified Quartzes from North Carolina ; Very choice Rutiles from North Carolina; Apophyllites, Magnetites, Calcites, Pyrites, ete., from — French Creek ; Dioptase, Alexandrites, Ouvarovites, Urals; Blendes, Magnetites, etc., from Binnenthal ; Augites (very fine) from Sweden; Enstatites (large) from Norway ; Many other rare and fine minerals, College orders especially solicited and satisfaction guaranteed. Pure minerals for Blowpipe Analysis, a specialty. GEO. L. ENGLISH & CO., Dealers in Minerals, 1512 Chestnut Street, - - Philadelphia, Pa. THE AMERICAN JOURNAL OF SCIENCE [THIRD SERIES] Art. XXX VI.—Wote on Harthquake-Intensity in San Fran- cisco; by Epwarp S8. HoupEen, LL.D., Director of the Lick Observatory. Towarp the end of 1887, the Regents of the University of California published a pamphlet prepared by me bearing the title “ List of Recorded Earthquakes in California, ete. ;” 1887 ; 8vo, pp. 78. This work contained all the information regard- ing California earthquakes which I have been able to collect. The information is presented in a popular rather than a scien- tific form, though the Introduction contains statistics, more or less valuable, relating to the distribution of the shocks by years, months and seasons. It is the object of the present note to obtain an estimate of the absolute value of the earthquake-intensity developed at San Francisco during our historic period. I am obliged to confine myself to San Francisco, whose records are very com- _plete, owing to the conscientious care of Mr. Thomas Tennant. With this end in view I have gone over the printed pamph- let and wherever the data were sufficiently exact, I have as- signed the intensity of each separate shock on the arbitrary scale of Rossi and Forel, omitting every doubtful case. The later papers of Professor- Rockwood already contained this datum. Omitting all doubtful cases, | found 948 shocks at 214 different stations in California which had been so well Am. Jour. Sct.—Tuirp SERIES, Vou. XXXV, No. 210.—Junz, 1888. 26 428 Holden—EKuarthquake-Intensity in San Francisco. reported as to allow an intensity on the scale, to be assigned with certainty. In San Francisco, 417 shocks in all have been recorded. Of these, 200 were accurately described. The Rosst-Forel Scale. I. Microseismic shock—recorded by a single seismograph, or by seismographs of the same model, but not putting seismographs of different patterns in motion : reported by experienced observers only. ; II. Shock recorded by several seismographs of different patterns; reported by a small number of persons at rest. III. Shock reported by anumber of persons at rest; duration or direction noted. IV. Shock reported by persons in motion; shaking of movable objects, doors and windows, cracking of ceilings. V. Shock felt generally by every one; furniture shaken; some bells rung. VI. General awakening of sleepers; general ringing of bells; swinging of chandeliers ; stopping of clocks; visible swaying of trees; some persons run out of buildings. VII. Overturning of loose objects; fall of plaster; striking of church bells; general fright, without damage to buildings. ; VIII. Fall of chimneys; cracks in the walls of buildings. TX. Partial or total destruction of some buildings. X. Great disasters; overturning of rocks; fissures in the surface of the earth; mountain slides. Determination of the mechanical equivalent of each degree on the Rossi-Forel scale. It is necessary to determine the value of each degree on the Rossi-Forel scale in terms of some natural units. This it is impossible to do with exactness, owing to the nature of the subject, and it is somewhat difficult to get results sufficiently exact to be used in practice. Referring to the Rossi-Forel scale, we find that degrees I, II, III correspond to the feelings of the observer—to his sen- sations. The rest of the scale (IV—X) refers chiefly to the effects of the shock in producing motion upon inanimate mat- ter. The problem is to get some kind of a common unit of a mechanical sort, and to express the various degrees of the scale in terms of this unit. There is no question as to what unit to employ. The researches of the Japanese seismologists have abundantly shown that the destruction of buildings, ete., is proportional to the acceleration produced by the earthquake shock itself in a mass connected with the earth’s surface. The earthquake motion is a wave-motion, and although it is not simple harmonic, it is necessary to assume it to be such to obtain a basis for computation. We assume then a = ampli- tude of the largest wave; IT = period of the largest wave; V pays T ae = 47’, na = intensity of the shock, defined mechanically = velocity of the impulse given by the shock; I = Holden—Earthquake-Intensity in San Francisco. 429 = destructive effect = the maximum acceleration due to the impulse. It would be logical to express I in fractions of the accelera- tion due to gravity, 2. ¢., 9810™™ per 1% As these fractions are usually small, it is convenient to give the values of I in terms of millimeters per 1°. The observations of Ewing, Milne and Sekiya on Japanese earthquakes give for each shock @ and T, from which V and I can be computed. Very frequently a description of the effects of the shock on buildings, etc., is given by them, which descrip- tion is often sufficiently minute to justify the characterization of the shock by one of the degrees of the Rossi- Forel scale. I have carefully examined all the writings of the three gen- tlemen named, accessible to me, and after rejecting all doubt- ful cases, | have found twenty-one shocks ranging in intensity from I to IX, in which the a and T were determined by in- struments and in which I could assign.the Rossi-Forel intensity with confidence. The following table is the result : Equivalents of the degrees of intensity of Earthquake shocks on the Rossi-Forel scale, in terms of the acceleration due to the velocity of the shock itself.* ee Vv? = Q°ra ila goat Te Rossi-Forel Scale. Intensity. Diff. I corresponds to 20™™ per ls aay II a 40 a (20) Til ob 60 a (20) IV tt 80 a (20) V “ 110 “ (30) VI ee 150 rf (40) VII “ 300 u“ (150) VIII ut 500 it (200) IX a 1200 i (700) So far as I know, this is the best determination possible from the meager data now available. The observations at Berkeley and Mt. Hamilton are espe- cially directed toward obtaining better values of these rela- tions. A few years of observations will determine them, at least for the lighter shocks (I-VI). * It is interesting to observe the influence of long period in diminishing the destructive effect of a shock of given amplitude. Thus a shock of intensity VIII 47a has [= —_— = 500™™ per 1* by observation. If T= 0:18, a = 0:1™™, while if T=18, a = 13™™, and so for other cases. " 430 Holden—KHarthquake-L[ntensity in San Francisco. Absolute intensity of EKarthquake action at San Francisco. 417 shocks of all intensities have been recorded at San Fran- cisco in the years 1808-1888. Of these, 200 were described so definitely that their intensities could be assigned on the Rossi- Forel scale with tolerable certainty. This work has been done with great care and is summarized in the following table : No. of shocks actually recorded at San Francisco (1808-1888) for which the in- tensity is known. Intensity on Rossi-Forel Scale. Number of Shocks. Pin ees coke iS Uae Oe Ne pap er Wa Ne ee RS a Re 8 EDT a aha SE ee Fe SES oe A RO ye Cet 4. BU ie aN ee ee eer pe DON em As ees eee YS BES Soo 6 55 OTe SSAA A ee CSA I Up eo Ce 50 WV ASR OR OSs UN GE Do Ne ne A 58 DATS Ee ets Os Bee PCR aie hs oa Se a 12 FVD 5 We URIS Be aS eh De eh ciee eee RANE a ees ACs tN SR ee 4 SV AM Ties set of Soke leans Laas Ee AN aay 9 ea ee 7 TEX Sie Se pte Ea as he ed ea rr 2, Total, sae t bse ee SNPS Me ae RE oie 200 Beside the 200 shocks of known intensity, there are 217 shocks printed in my catalogue. No doubt a great number of the lighter shocks (I, II, I11,) are not recorded at all. Earthquake action is so irregular and lawless, that it is not possible to make any estimate however rough of the number of these lighter shocks. Experience has amply proved that the average intensity of San Francisco shocks is not above IV on the Rossi-Forel scale. The vast majority of our shocks are II and III and the average is certainly below IV. I shall, therefore, assume this fact as a basis for computation. The 200 shocks of known intensity are evaluated and summed up in the following table: ‘ Units of Acceleration. 8 shocks of intensity I correspond to 8x 20 = 160 Anon e of II x i Zee ZO SS 160 Bi te III % Duis OO = 3300 BOM ie IV sf HOS > SO. = 4000 58 ft a V ae Besos AI SS 6380 12 uy i VI oe Sra eno) Oe — 1800 Ae ee a Vil af abs GXIXD)) = 1200 feat CO inary o Nepe a VIII “A PTse AN) eS S50) 2 ff i IX 0: SAS NAO) eS 2400 200 recorded shocks of known intensities correspond to 22900 units. The average recorded shock corresponds to | = 114 units or approximately to V on the scale. This simply proves that all, or nearly all, the shocks of intensity V and more severe have been recorded and that the lighter shocks have been neglected. As has been said 417 shocks in all have been noted (of which only 200 are accurately described). I assume the 217 shocks of Holden—Earthquake-Intensity in San Francisco. 481 @ unknown intensities to have had between 48 and 49 units of intensity each, or 10460 units in all. This amounts to sup- posing our average shock to be of intensity 1V. In this way the table will stand : Units of Acceleration. 217 shocks of unknown intensity give ___..----=---------- 10460 HOO EE Teyana, TNIENSN? OVO) a oos coos ae oesooonsedae 22900 417 shocks recorded (1808-1888) give _____.._------------ 33360 The average shock is of intensity IV corresponding to 80 units or to ;4,d-part of the acceleration due to gravity. The total intensity of 83360 units has been experienced in 80 years and corresponds to 3-4 the acceleration due to gravity. That is if all the earthquake force which has been expended in San Francisco during the past 80 years were concentrated so as to act at a single instant, it would be capable of producing an acceleration of 3-4 times that of gravity or about 109 feet per second. The total earthquake intensity during the 80 years is nearly equal to the intensity of 28 separate shocks as severe as that of 1868, but it has been doled out so gently and gradually that we have scarcely known of it. On the average 392 units of intensity have been developed during each one of the 80 years (1808-88). This will allow for six shocks of intensity III per year or one every two months. In fact 417 shocks have been recorded in the 960 months. I believe that my earthquake catalogue as printed and the present note, contain nearly all the precise information which can be extracted from our past records, at this time. The automatic earthquake registers now in use at the Uni- versity of California, Berkeley (under the care of Professors Le Conte and Soulé) and at the Lick Observatory, Mount Hamilton, will afford valuable data after a few years. T am greatly in hopes that the chiefs of the U. 8. Geological Survey and of the U. 8. Signal Bureau may find it practicable to establish and care for seismometric stations in the state. The cost of such stations is small. I find that the excellent duplex-pendulum instrument of Professor Ewing can be satis- factorily duplicated for $15. The California Electric Works, 35 Market street, San Francisco, is now prepared to furnish such instruments at that price. If a sufficient number of stations can be established in California, it seems to me that we may look forward to the collection of data of real theoretical and of some practical importance within comparatively few years. 432 CU. A. White—Relation of the Laramie Group Arr. XXX VII.—On the relation of the Laramie Group to earlier and later Formations ; by CHARLES A. WHITE. [Published by permission of the Director of the U. 8S. Geological Survey.]} WHILE some geologists and paleontologists have claimed the Laramie Group as belonging to the Tertiary, others have as earnestly asserted its Cretaceous age. In the course of my own investigations I have found so many of the paleontological characteristics of that formation to be of little or no value as indicating its age, and other evidence to be so conflicting in character,* that, in my somewhat numerous writings concern- ing that group, I have hitherto treated it as representing a gradual transition from the Cretaceous to the Tertiary. In- vestigations concerning the physical conditions which attended the deposition of that great group of strata, and the biological conditions which prevailed during its accumulation are cer- tainly of far more importance than the mere question of its contemporaneity with other formations, which, as regards any formation, can at best be learned only approximately. Still this latter question is by no means a trifling one, and any facts bearing upon it ought to receive due consideration. The ob- ject of this article is to record certain lately acquired facts re- lating to this question, and to present the bearing upon it of others which have before been published. During the twelve years preceding the autumn of 1887, in which I had made extensive studies and observations concern- ing the Laramie Group, I was never able to obtain any per- sonal knowledge_ of. the actual stratigraphical relation of that group to any of the marine Tertiary groups which border various portions of North America. I had studied the Lara- mie in numerous. districts from the State of Nuevo Leon, Mexico, on the south to northern Montana on the north; and wherever the base of the formation was observable it was found to rest directly and conformably upon the uppermost of the marine Cretaceous formations.t Furthermore, wherever any strata were found resting upon the Laramie they were always those of the great fresh-water Tertiary series; but I had not then traced the Laramie into a district within which marine Tertiary strata were known to exist. That is, in tra- * See White, C. A., On the commingling of ancient faunal and modern floral types in the Laramie Group. This Journal, III, vol. xxvi, pp. 120-123. + For an account of the intimate stratigraphical relation of the Laramie to the marine Cretaceous formation next beneath it; and of a partial faunal connection of the Laramie with freshwater Tertiary formation next above it, see this Journal, III, vol. xxxiii, pp. 364-374. to earlier and later Formations. 433 cing the Laramie into Mexico I had followed the trend of that formation from the north, and thus passed to the westward of the outcrops of the Gulf Tertiaries. In 1884, Professor E. D. Cope announced that he had found “the Claiborne beds resting immediately upon the Laramie at Laredo,”* Texas; but he then mentioned no correlated facts in support of this important announcement and, so far as | am aware, none have since been published. The known south- eastward trend of the Laramie, and the circling, and therefore converging, trend of the Gulf series of formations made it. evi- dent that the district traversed by the lower Rio Grande would be found to be the most promising field in which to search for the stratigraphical relation between the Laramie and the Eocene Tertiary. With this object in view, I last autumn visited that region and had the satisfaction of confirm- ing the observation previously made by Professor Cope. Starting at Eagle Pass, Texas, I proceeded down upon the Texan side of the valley of the Rio Grande to Laredo, mak- ing observations by the way. The strata representing the Fox Hills Group of the western section and the Ripley Group of the eastern, were found to dip gradually in the direction of the course of the river, and to receive those of the Laramie Group upon them, the older strata passing finally from view in that direction. The strata which are exposed in the bluffs along the left bank of the Rio Grande from twenty-five to thirty miles above Laredo, and which bear one or more workable beds of coal there, are referred confidently to the Laramie, although they afforded me only a few imperfect fossils. ‘These strata dip gradually to the southeastward or approximately in the direc- tion of the river’s course, and disappear beneath the sandy strata of the Eocene Tertiary some ten or twelve miles above Laredo. Below this, and all around Laredo, the strata which I found exposed are of Eocene age; and in many places they bear an abundance of characteristic fossils. Going westward from Laredo to Lampazos in Mexico, I was able to recognize the Eocene strata for a distance of about twenty miles, beyond which the underlying rocks are so fully obscured by the debris of the plain that no exposures were observed until the neighborhood of Lampazos was reached. The known presence of Laramie strata, a few miles to the northward of Lampazos, which bear characteristic molluscan fossils of that formation, however, leaves no room for doubt that the Laramie is overlaid by the Eocene upon the Mexican side of the Rio Grande, just as it is upon the Texan side. * Proc. Am. Philos. Soc., vol. xxi, p. 615. 484 C. A. White—Relation of the Laramie Group While I have no doubt as to the Laramie age of the strata referred to, which I observed on both sides of the Rio Grande, and none as to the Eocene age of the strata which I found overlying them, I am by no means certain that the lowermost strata which I found resting upon the Laramie near Laredo represent the lowermost strata of the Eocene division of the Gulf series. Indeed, so far as I could discover, no equivalent of the “ Northern Lignite” the lowermost member of the Eocene of Hilgard’s Mississippi section, exists in the region: round about Laredo, unless the coal-bearing strata of the upper portion of the Laramie are really its equivalent. I am dis- posed to accept this view of the case, and to regard the Northern Lignite of the Mississippi section and its equivalents elsewhere, including the uppermost strata of the Laramie, as really of Eocene age. Those lignitic beds in the State of Mississippi and in eastern Texas rest directly upon the Ripley Group, the uppermost of the marine Cretaceous series of the Gulf region, just as the Laramie rests upon the equivalent of the Fox Hills and Ripley Groups in western Texas. But the faunal hiatus between the Ripley and marine Eocene beds in those eastern regions is so great that one may reasonably suppose it to represent sufficient time for the deposition of a larger and more important forma- tion than the lignitic beds alone constitute there; such a formation, for example, as is the Laramie Group. Still, the fact remains that the Laramie Group as a whole is, in the val- ley of the lower Rio Grande, overlaid by strata which all agree to be of Eocene age. This fact makes it certain that the Lara- mie Group as a whole is older than certain well marked Eocene strata; and it is also presumptive evidence of the Cretaceous age of at least the greater part of the Laramie. There are also other facts pointing to the same conclusion which will be discussed in the following paragraphs. Several years ago, Dr. G. M. Dawson announced the exist- ence, in that portion of British America which is in large part drained by the Saskatchewan River and its tributaries, of a formation in the Cretaceous series which had not before been recognized, and to which he gave the name of “ Belly River series.” Since then both he and other members of the Cana- dian Geological Survey have from time to time published accounts of the same formation.* They report this formation as resting upon the equivalent of the combined Benton and Niobrara groups of Meek & Hayden’s section of the Upper *See Dawson, Geo. M., Geol. and Nat. Hist. Survey Canada for 1882-83-84. C. pp. 1-169. Dawson, Geo. M., ib. for 1885, B. p. 166. McConnell, R. G., ib. for 1885, C. pp. 1-85. Whiteaves, J. F., Contributions to Canadian Paleontology, vol. i, Part I, 1885. to earlier and later Formations. : 435 Missouri Cretaceous, and as underlying strata which bear mol- lusean forms such as characterize the Pierre and Fox Hills groups of the same section. The fossils which they report as coming from the Belly River formation are wholly different from those that charac- terize the formations which underlie it, as well as the one which immediately overlies it. Their collections not only in- dicate the absence of true marine forms from the Belly River formation, and the presence in it of remains of both verte- brate* and invertebrate+ faunas which are similar to those of the Laramie, but they contain a considerable number of mol- lusean forms which are specifically identical with a part of those which characterize the Laramie Group. Those geologists furthermore report that the marine Creta- ceous strata which overlie the Belly River formation are, in turn overlaid by true Laramie strata, bearing the characteristic fossils of that formation. The following table shows the rela- tion of the forementioned formations, with one another; and also the relation of Dr. Dawson’s section with the Upper Mis- souri section of Meek & Hayden. Meek and Hayden. Dawson.t Judith River beds [ Laramie|- Laramie. No. 5. Fox Hills Group med No. 4, Fort Pierre Group sail i Fox Hills and Pierre.§ Wanting yess. eee tl Belly River beds. No. 3. Niobrara Gr . eo ie Botte eat t ay aes Benton and (Niobrara) ? No ee Dakotar Groupe so: 22 oe: Dakota ; and upper part of Kootanie. Considerable paleontological difference between the com- bined Benton and Niobrara groups beneath, and the Pierre and Fox Hills groups above, has long been known to exist. In recognition of this difference Meek designated the two divis- ions respectively, as the “upper” and “lower series”; and as ‘“Karlier and Later Cretaceous.” Still, those formations have been generally regarded by geologists as forming a continuous series of marine deposits which was unbroken as such until the * Professor E. D. Cope has examined collections of vertebrate remains from the Belly River formations, and has personally informed me that they consist wholly of Laramie types. ee Cont. Canadian Paleontology, vol. i, Part I, pp. 55-77; and plates IX an ¢ See Ann. Rep. Geol. and Nat. Hist. Surv. Canada for 1885, p. 166, B. $ It will be seen that Dr. Dawson combines together the Fox Hills and Pierre, and also the Benton and Niobrara divisions, recognizing only a single formation in each of the two cases. This combination has also long been adopted by mem- bers of the U. 8. Geological Survey, on the ground that there is no sufficient rea- son for separating them except for occasional local study. 436 0. A. White—Relation of the Laramie Group uppermost one received upon it the great brackish- and-fresh- water Laramie formation. Therefore the first announcement of Dr. Dawson’s discovery was received with not a little sur- prise by the geologists who had studied the formations re- ferred to in more southern regions. I have never visited the Saskatchewan region and cannot therefore speak of the formations there from personal observa- tion. But after carefully reading the accounts which have been published by the Canadian geologists, and having had grati- fying personal interviews upon the subject with both Dr. Daw- son and Mr. Whiteaves, I can now see no good reason to doubt the correctness of their observations. Accepting their conelu- sions, it appears that in the region referred to, the deposition of marine Cretaceous strata was interrupted at the close of the Niobrara epoch by such a change in physical conditions as caused the introduction upon the area which had been occu- pied by marine waters of a brackish- and fresh-water forma- tion similar to the Laramie. It also appears that upon the completion of that brackish- and fresh water formation, marine conditions, similar to the first, were resumed; and the Pierre- Fox Hills formation was then deposited. Furthermore, upon the completion of the last named formation, brackish- and fresh-water conditions were resumed, over the same area, when the Laramie Group was deposited. The specific identity of a considerable part of the molluscan fauna of the Belly River formation with Laramie forms makes it necessary to assume that both faunas had a common origin. This proposition being accepted, the stratigraphical relation of the Beily River formation with the Laramie makes it further necessary to assume that at least a large part of the fauna of the Laramie was derived directly from that of the Belly River formation. The introduction of a true marine formation between the two which are of brackish. and-fresh-water origin precludes the supposition that the earlier fauna prevailed over the same ‘area which it first occupied during the deposition of that ma- rine formation. The presence of certain identical species in both the Belly River and Laramie formations is presumptive ‘proof that those species somehow and somewhere survived dur- ing the time that the Pierre-Fox Hills formation was in course of deposition. The absence of any equivalent of the Belly River formation from the marine Cretaceous series which so extensively prevails to the southward of the Missouri river seems to indicate that the molluscan fauna of that formation originated in that northern region, and that it did not then extend far to the southward. to earlier and later Formations. 437 The species referred to were gill-bearing mollusca, and to have survived they must have had a continuously congenial habitat. That is, they were in part fresh-water and in part brackish-water forms, and those respective conditions of the waters in which they lived must have been somewhere contin- uous to have made the survival of those species possible. It is therefore probable that the Belly River and Laramie faunas somewhere became blended together as one, upon the final retirement of the marine Cretaceous waters; although no such blending of the.strata of those formations has yet been dis- covered. Whatever may have been the facts in the case, the specific identity of those Belly River and Laramie mollusca makes it necessary to assume that at least a considerable part of the Laramie molluscan fauna began its existence long be- fore the close of the Cretaceous period as it is represented by marine formations. This faunal relationship between the Belly River and Laramie formations also strongly connects the latter formation with the Cretaceous. The two categories of facts relating to stratigraphical rela- tions of the Laramie which have been presented in the preced- ing paragraphs of this article, and which are strongly sug- gestive of its Cretaceous age, have not before been publicly discussed in that connection. There are however two other categories, one relating to physical, and the other to paleonto- logical phenomena which have been much discussed, both of which have been held by many persons to prove conclusively . the Cretaceous age of the Laramie. The paleontological fact which has most influenced the views referred to, and the only one that need be mentioned here, is the occurrence of dino- saurian remains in the Laramie, extending even to some of its uppermost strata. The physical phenomena referred to pertain to certain of the orogenic and epirogenic*® movements which have taken place within the great region occupied by the Laramie Group. The movements referred to are those which on the one hand have resulted in the present elevation of that great western portion of North America, and on the other, in such great folds, for. exaniple, as those out of which the Uinta, and Rocky Mountains have been carved. In at least the greater part, and apparently all, of those movements the Laramie Group is found to have been fully involved together with all the formations beneath it; while the later formations were not so fully involved. Thus there appears to have been within that region no phys- ical break in the continuous accumulation of material compos: ing the true marine Cretaceous formations, and none of importance until the close of the Laramie period, if we ex- * Ktym. Hrecpoc; mainland, or continent. 438 Williams—Gabbros and Diorites of the Cortlandt Series. cept the great hiatus which probably exists between the Carboniferous, and the Uinta Sandstone. The sedimenta- tion also seems to have been continuous from the upper- most of the marine Cretaceous formations into the Laramie, although the faunas of these respective groups are widely dif- ferent. Consequently field geologists have always experienced great difficulty, in the frequent absence of distinguishing fos- sils, in separating that marine Cretaceous formation from the Laramie; and they have therefore been disposed to regard the latter as a Cretaceous formation. While I still believe that at least the upper strata of- the Laramie Group represents a gradual transition from the Cre- taceous to the Tertiary period, the facts which have been pre- sented m the preceding paragraphs certainly constitute strong presumptive evidence of the Cretaceous age of the greater part of it. Judging from my own investigations, it is regarded as impossible to draw either a paleontological or a stratigraph- ical dividing line between the Cretaceous and Tertiary por- tions of the Laramie Group. Therefore the established cus- tom of geologists in formulating a scheme of classification of the formations, seems to require that the whole group should be classed either as Cretaceous or Tertiary. It is not only con- ceivable, but it is natural to suppose, that a transitional forma- tion might possess characteristics which, so far as evidence of age is concerned, would be nearly equally balanced between two periods. I believe the Chico-Téjon series of California, for example, actually presents just such a case. The evidence, as a whole in the case of the Laramie however does not appear to be so well balanced, and in my future writings I shall prob- ably class the Laramie as a Cretaceous formation ; although I shall regard this practice as little more than a matter of con- ventional convenience. Art. XXXVIIL—The Gabbros and Diorites of the “ Cort- landt Series” on the Hudson River near Peekskill, NV. Y¥.; by GrorGE H. WILLIAMS. In two former papers* I have described two types—perido- tites and norites—which form members of that complex group of massive rocks occurring in the northwestern corner of West- chester County, N. Y., and designated by Prof. J. D. Dana as the “ Cortlandt Series.” The area occupied by these rocks— about twenty-five square miles in extent and nearly coincident * This Journal, ITI, xxxi, Jan. 1886, p.26; ib., xxxiii, Feb. and March, 1887, p. 135 and p. 191. Williams—Gabbros and Diorites of the Cortlandt Series. 439 with Cortlandt township—is mainly composed of norite, the many varieties of which were described in my last paper. In the southeastern and southwestern corners of the township, as well as on Stony Point on the opposite side of the Hudson River, olivine-norites and peridotites are found, while at other localities, mostly in the southwestern portion of the area, still different but closely allied types of massive rocks occur. These, which form the subject of the present communication, are :— Class III, Gabbro, Class IV, Diorite, Class V, Mica-Diorite. These rocks are everywhere connected so closely by inter- mediate forms that they may, to a certain extent, be regarded as facies of the norite. Indeed, even in the types most widely. removed from the prevailing rock hypersthene is very liable to recur. There are enough general resemblances and con- necting links to join all the rocks of this series into a geologi- eal unit ; and at the same time there are differences sufticient to show that many types were successively produced from the same igneous focus. Crass III. Gassro (von Buch.) 1. Gabbro proper.—This rock is to be found at only a few isolated localities, of which the most representative is “* Mun- ger’s Corners,” a short distance west of Montrose Station on the N.Y. C.& H.R. BR. Prof. Dana has designated this place as “q” on his map, and describes the occurrence as “a grayish white augitic rock.”* It is represented by several slides in both Prof. Dana’s and the Johns Hopkins University collec- tion. (No. 42 and K, Mt. 13 (D)). Under the microscope this rock appears as an ageregate of allotriomorphous plagioclase and augite grains. The latter mineral is of a reddish or grayish color, both often appear- ing in the same crystal individual. It is without pleochroism and frequently shows a pronounced orthopinacoidal parting. The substance of the augite or diallage is for the most part un- altered, although a little green uralite is occasionally devel- oped. Accessory constituents in this rock are biotite, apatite, ilmenite and sphene. The last named mineral is quite abun- dantly represented in all sections and appears to have resulted from the alteration of the titanic iron. The gabbro shows evidence of great dynamic action. The twinning lamelle of the plagioclase are much curved and both * This Journal, III, xx, p. 195, and p. 211, Sept. 1880. 440 Williams— Brie and Diorites of the Cortlandt Series. the feldspar and the augite are often peripherally granulated by crushing and rubbing. Another rock (No. 44) occurring at Centerville on the south side of Prof. Dana’s limestone 4,* is in all respects identical with the gabbro at Munger’s Corners. The eruptive dykes which occur in such intimate ‘association with the limestone at the southern end of Verplanck Point, are in part gabbros ; in part mica- or hornblende diorites. No. 111, from one of the narrowest of these dikes, is quite like the gabbros last described, except that it is finer grained. Its augite also is more extensively changed to uralite. The thin section of this specimen includes some of the limestone in con- tact with the eruptive rock. This is altered by the meta- morphic action into a granular aggregate of pale green py- roxene together with some pale hornblende and pleonaste. 2. Mica-Gabbro.—The presence of accessory biotite in the gabbros has been mentioned above; in some cases this min- eral becomes so largely developed _as to equal or even exceed the amount of augite present. Thus No. 109 and VK 5, of Prof. Dana’s collection, both from dikes at Verplanck Point, differ only from the normal gabbro of this locality in the in- creased amount of biotite present. No. 45 also is only a bio- tite modification of the Centerville gabbro above mentioned. The most interesting point in regard to the gabbros of the Cortlandt Area is that they always (so far as observations yet extend), occur «immediately beside limestone. They seem to represent a local modification of the norite produced by an increase of lime, for this, as is well known, would change the orthorhombic magnesian hypersthene to a monoclinic pyroxene. Cuass IV. Diorire. (Haiiy.) The hornblende, which imparts the essential character to this class of rocks, is compact and homogeneous in structure, pos- sessing every appearance of a primary constituent. It occurs in allotriomor phous individuals which vary in size according to the coarseness of the rock-grain. In the main this hornblende is identical with that already described at length from the hornblende-peridotite of Stony Point.t In some instances this hornblende contains the same delicate inclusions, while in others these are totally wanting. Its pleochroism is always strong, and its color either a deep chestnut brown or a bright green. More rarely it shows by transmitted light a color in- termediate between these two. s Wid. the map in Prof. Dana’s article. This Journal, III, xx, p. 195, Sept., 1880. + This Journal, III, xxxi, p. 31, Jan. 1886. Williams—Gabbros and Diorites of the Cortlandt Series. 441 The two types of diorite produced by the presence of brown or of green hornblende are quite distinct both in their occur- rence and relationships. The former is always associated with pyroxene rocks and tends to pass gradually into norite, gab- bro, or pyroxenite; by a total loss of feldspar these diorites may also develop into massive hornblendites. The diorites composed of green hornblende, on the other hand, show their closest relationship to the mica-bearing rocks. The grain of these diorites varies extremely, from apha- nitic varieties to such as have hornblende individuals over six inches in length. 1. Brown-hornblende-Diorite.—This type is best developed in the wonderfully complicated net-work of massive rocks ex- posed on the river bank along the northern portion of Mon- trose Point. The brown diorite is most intimately associated with norite, and grades, on the one hand into this, and on the other into a massive brown hornblendite. The other constitu- ents are triclinic feldspar (presumably the same andesine as occurs in the norites),* apatite and magnetite. Accessory hy- persthene is common by which the diorite shows its tendency to grade into the norite. The brown diorites extend, with exactly the same associa- tions, eastward from Montrose Point nearly as far as Mon- trose Station, as is shown by a large number of sections in both the University and in Prof. Dana’s collection. They were, however, not encountered in other parts of the Cort- landt Area. 2. Hornblendite.—Both coarse- and fine-grained aggregates of compact brown hornblende occur abundantly along the northern portion of Montrose Point. These rocks have a glis- tening black color and are most intimately associated with the norites, hyperites, diorites, and pyroxenites which also occur there. No more complicated interpenetration of eruptive rock-types could possibly be imagined than is displayed at this locality—every rock includes and forms dykes in every other; and at the same time every type passes by gradual changes in its mineralogical composition into every other one! The striking examples of the passage by paramorphism of pyroxene into compact brown hornblende described some time since by the writer,t oceur in rocks from Montrose Point intermediate between pyroxenite and hornblendite. The . origin of the brown hornblende from both the diallage and the hypersthene is so apparent as to suggest the derivation of all the hornblendites by paramorphism from preéxistent pyroxenites. * This Journal, III, xxxiii, p. 140, Feb., 1886. + This Journal, III, xxviii, p. 261, et seq., Oct., 1884, 442 Williams—Gabbros and Diorites of the Cortlandt Series. Specimen Mt. 7 of Prof. Dana’s collection is interesting as illustrating the alterations which one of the coarser hornblend- ites from Montrose Point has undergone. The change of the brown hornblende is to serpentine and tale. Hornblendite composed entirely of green hornblende is rare within the Cortlandt Area. It does, however, occur among the dykes intersecting the limestone at Verplanck Point, as shown in section VK.1. of Prof. Dana’s collection. 3. Green-hornblende-Diorite.—Typical diorites of this class are not common inthe Cortlandt Area. Those observed occur in narrow dykes on Montrose or Verplanck Points. These diorites which are wholly free from biotite always contain a hornblende, which, though it may properly be called green, has nevertheless a decidedly brownish tinge. On the whole the relationship of these rocks with the brown hornblende diorites is much closer than it is to those of the following class. By far the most typical development of the green-hornblende diorites belonging to the “ Cortlandt Series,’ occurs along the edge of the steep rock wall which extends westward from Cruger’s Station, toward Montrose Point. This abrupt ascent marks the contact between the massive rocks and the softer, though much metamorphosed schists. These diorites, however, always carry a large amount of biotite and therefore are more properly classed as 4. Mica-hornblende-Diorites.—The association between this type and the pure mica-diorite (class V) is extremely intimate and there is everywhere observable a tendency toward the de- velopment of the latter rock by the total replacement of the hornblende by the biotite. The most prominent microscopical peculiarity of these green diorites is their sudden and extreme alterations of grain; very coarse and fine varieties occurring side by side in the same ex- posure, in a manner unequalled in any other part of the entire Cortlandt Area. The best locality to observe this structure is just above the brick-sheds near Cruger’s. Station, at a point marked “” on Professor Dana’s map.* The constant mineral constituents of these diorites are a finely striated plagioclase, green compact hornblende, biotite, magnetite, epidote and apatite. Less abundant are an unstri- ated feldspar (orthoclase) and quartz. Garnet is a frequent endo-metamorphie product near the contact of the diorite with the schists. The hornblende differs only in its color from the compact brown hornblende already described in other mem- bers of the “Cortlandt Series.” It occurs in irregular indi- viduals which are filled with magnetite inclusions. The color is a deep green, often inclining to bluish-green, and the pleo- chroism is very intense. * Loe. cit. Williams—Gabbros and Diorites of the Cortlandt Series. 443 All the other constituents of the coarse hornblende-mica- diorites of Cruger’s Point are identical with those of the typi- eal and more abundant mica-diorite. They may therefore best be described in connection with this rock (class V), of which indeed the type now under consideration is only a par- ticular facies. A very fine-grained variety of the hornblende-mica-diorite is quite common as a dike rock on both Montrose and Stony Points. In many respects this presents a resemblance to Rosen- busch’s group of droritic lamprophyres or kersantites, and yet its extreme freshness and freedom from calcite, the frequently granular form of the feldspar, and the association in nearly equal proportions of biotite and green hornblende while augite is wholly wanting, separate this rock from any of the many varieties of kersantite described in Rosenbusch’s recent work. The fine-grained, dark-gray dikes of this rock may be most advantageously seen in the cuttings on the West Shore Railroad through and near Stony Point. Here they intersect the much contorted schists, the peridotite and the mica-diorite and afford the evidence upon which Professor Dana admitted the truly eruptive nature of at least the more basic members of the “‘Cortlandt Series.” * These dikes are, however, shown by the microscope to belong to the more acid rather than to the more basic of the massive rocks. Cuass V. Mica-Diorire. This rock is more uniform in its character than any other of the important members of the Cortlandt Series. It is in all cases essentially a rather coarse-grained aggregate of plagioclase and biotite, with accessory epidote, apatite and magnetite ; often a little orthoclase and quartz; and sometimes garnet. The latter mineral is an endo-metamorphic product, and is to be found only near the contact with the schists. The mica-diorite occurs only in the south-western part of the Cortlandt area; on the east side of the Hudson River west of Cruger’s station, and on the west side at Stony Point (see map in my paper on the Cortlandt Peridotite, this Journal, Jan., 1886, p. 29). No such pure type of mica-dioritet has ever, to my knowl- edge, been described from any locality. * This Journal, III, xxviii, p. 384, Nov., 1884. « + Professor J. D. Dana called this rock sod-granite, (this Journal, III, xx, p. 198), and later hemi-dioryte, (1b., xxv, p. 478). The first name was proposed by Haughton in 1856 to designate, as it still does, a true granite in which the soda is in excess of the potash, (cf. A. Gerhard, Neues Jahrb. fiir Min., etc., 1887, II, Am. Jour. Sct.—TuHirp Series, VoL. XXXV, No. 210.—Junz, 1888. 27 444. Welliams—Gabbros and Diorites of the Cortlandt Series. I have as yet been unable to secure a complete analysis of this rock, but an average of four determinations of its silica gives 53°94 per cent. This is sufficient of itself to establish the dioritic nature of the rock. The feldspathic constituent varies considerably in composi- tion as may be seen from the different extinction- angles occurring even in the same individual; nevertheless a number of specific gravity determinations, lying between 2°67 and 27648, show that the mineral belongs to the oligoclase-andesine series. Some of this plagioclase is notable for being almost free from twinning striation. This is especially true for section No. 87, from Stony Point, whose feldspar was particularly studied. In other cases the striation is finely displayed, not infrequently according to both the albite and pericline laws. A zonal structure is common, and the delicate inclusions deseribed in detail in the feldspars of the norites,* are sometimes abundant and sometimes absent. _ The mica, which constitutes the only other essential constit- uent of these rocks, is a biotite very rich in iron. Its absorp- tion is intense and basal sections are only translucent when very thin. Their color is then a greenish-brown. The optical angle is so small that it is impossible to determine whether the mineral is anomite or meroxene. The mica contains no other inclusions than magnetite grains and apatite needles. None of the pleochroic aureoles so common in the granites were observed. The presence of ,orthoclase was not positively substantiated in these rocks. An unstriated plagioclase might easily be mistaken for orthoclase. Quartz occurs sparingly in grains, which, from their allotrio- morphous character, were evidently the last product of crystallization. These are frequently penetrated in every direction by the minute and indeterminate black needles mentioned by Hawes, Rosenbusch and others. Magnetite is universally distributed. Apatite occurs in rare abundance, size and perfection. Sphene and zircon are often present, and epidote of somewhat exceptional character is very common, especially in the mica-diorite from Stony Point. This mineral is of a pale green color, without pleochroism and its p. 267). Prof. Dana objects to the term mica-diorite, because (1) the original diorite was a hornblende rock and (2) because hornblende and mica are widely different minerals. It must, however, be remembered that, although these two minerals are co different, they play a very similar ré/e in rock-composition. The name mica-diorite is here retained because. in spite of all objections to it, it has the very great advantage of being readily intelligible to students of petrography the world over,—something that cannot be said of any other term which might bé proposed in its place. * This Journal, III, xxxiii, p. 141, Feb., 1887. Williams— Gabbros and Diorites of the Cortlandt Series. 445 source cannot be traced in the alteration of any older constitu- ent. It is generally without terminations but is most remarkable for the peculiar eaten or corroded aspect presented by the crystals, (see fig.) These are often divided into the most com- plicated fret-work of inter- locking tongues. The cleav- age is parallel to the long di- rection of the crystal, and the extinction is parallel to the cleavage lines. The mineral is shown to be epidote and po # pee ae by the spidote in Mica-Diorite (No. 28, optic axes is perpendicular to the cleavage lines. Twin crys tals of this epidote occur as shown in the figure. The bright red garnet crystals which are so often found in this rock are most frequent near the edge of its mass and are doubtless an endo-metamorphic product. The structure of the mica-diorite is hyp-idiomorphous in the sense of Rosenbusch. It is most closely connected with the diorite proper, into which it grades through the mica- hornblende-diorites as explained above. On the other hand, it passes into the norites through the group of the mica-norites.* Some of these rocks contain much more biotite than hypersthene, closely resembling the hypersthene-bearing mica-diorite from Campo Major in Portugal described by Meriant+ and the norite facies of the Klausen diorite mass described by Teller and von John.{ In the latter rock the feldspar has also been shown to belong to the andesine series. Quartz-Mica-Diorite.—A quite exceptional member of the massive rocks of the ‘‘ Cortlandt Series” occurs a short distance eastward of Montrose Station. This has a very light color with only comparatively rare and small flakes of biotite scat- tered through it. It forms a bed of moderate thickness within the dark massive norite against which it is sharply defined, i. e., there is here nothing like a gradual transition from the one rock to the other. Professor Dana has described this rock as a granitoid mica- * This Journal, III, xxxiii, p. 191, March, 1887. ¢ Neues Jahrbuch fiir Min., etc., Beil. Bd. III, p. 292, 1885. ¢ Jahrb. k. k. geol. Reichsanst., xxxii, p. 589, 1882. 446 Welliams—Gabbros and Diorites of the Cortlandt Series. ceous quartzite,* but a careful petrographical study of it shows that it is a massive rock, best to be designated as a porphyritic quartz-mica-diorite. Under the microscope well-formed crystals of feldspar are seen imbedded in a rather coarse-grained groundmass com- posed mostly of quartz and feldspar. The porphyritie erys- tals possess a beautiful zonal structure and sometimes, though not commonly, polysynthetic twinning striation. No porphy- ritic quartz occurs. The groundmass is a mosaic of interlocking grains unlike the structure of a quartzite. It contains biotite and epidote exactly like that characteristic of the mica-diorite proper, ex- cept that their amount is here much less. The feldspar of the groundmass is sometimes striated, sometimes not. Specific ravity determinations made with the Thoulet solution show all the feldspar of this rock to be plagioclase, varying between 2°63 and 2°67. This renders its separation from the quartz and the quantitative determination of the latter impossible. This rock differs from the mica-diorite proper only in its greater amount of quartz and the proportionately smaller amount of biotite and epidote. It may be regarded as a vari- ety of the former rock and as the most acid type of the whole “Series,” which is throughout essentially a plagioclastic one. We have now, within the limits of this and of my two for- mer papers traced out the following types of basic and ultra- basie rock which form members of the group called by Pro- fessor Dana the “Cortlandt Series.” Class I. Peridotite. Class IV. Diorite. 1. Hornblende - Peridotite 1. Brown-hornblende- Diorite. (Cortlandtite). 2. Hornblendite. 2, Augite-Peridotite(Pikrite). 3. Green-hornblende-Diorite. Class II. Norite. 4, Mica-Hornblende-Diorite. 1. Norite proper. ; ClassV. Mica-Diorite. (‘So- 2. Hornblende-N orite. da-granite,” ‘ Hemidioryte,” 3. Mica-Norite. Dana.) 4,.-Augite-Norite (Hyperite). 1. Mica-Diorite proper. 5. Pyroxenite. 2. Hornblendic Mica-Diorite. Class III. Gabbro. 3. Hypersthenic Mica-Diorite. 1. Gabbro proper. 4. Quartz-Mica-Diorite. 2. Mica-Gabbro. In spite of the extent to which the subdivision of the vari- ous types has been carried in the descriptions, the actual vari- ety of intermediate or transitional forms has not been ade- quately represented. In order to show more completely the * This Journal, III, xx, p. 218, Sept., 1880. Willtams— Gabbros and Diorites of the Cortland: Series. 447% number and relationships of these intermediate members and to connect all the various types together in one geological unit or “ Series,” the following diagram has been constructed. All Hornblende- Rock Hornblendite Py roxenite Hornblende Gabbro Rusitcs GCABBRO Diorite Augite- Hornblende Norite ypersthene Gabbro Hype rsthene Diorite Hornblende Norite Mica Hornblendé Diorite Mica- Gabbro Augite Mica Norite MICA DIORITE Quartz Mica- Diorite varieties represented in the circles correspond to actual speci- mens collected within the Cortlandt Area and many others might have justified a still more minute differentiation. The lines connecting the circles indicate the directions in which the best marked transitions take place. These rocks present an admirable example of what are called Jocees of a geological unit mass. In spite of their great petro- graphical variety, they are everywhere connected by transi- tional forms into the closest relationship. And yet we need not regard all the rocks as having been formed simultane- 448 W. SJ. McGee—Three Hormutions ef ously. The region was probably for a long time the scene of eruptive activity. At different periods different types may have been produced which broke through these already solidi- fied. The quartz-mica-diorite near Montrose Station seems to be a later intrusion into the older and more basic norite. This will comet what the writer has to say on the massive rocks of the “Cortlandt Series.” These are however so ex- tremely varied that their study can hardly be said to be more than begun. It is earnestly hoped that some one may in future work out all their manifold variations and relationships more completely than the writer, at such a distance from the field, has Been able to do. Enough perhaps has already been said regarding the nature and mode of occurrence of these rocks to place their truly eruptive nature beyond all question; nevertheless all the evi- dence bearing on this point may be more advantageously sum- marized at the conclusion of the next and final paper, which will deal with the phenomena of contact metamorphism pro- duced by the massive rocks in the adjoining schists. Petrographical Laboratory, Johns Hopkins University, Baltimore, Jan. 27, 1888. ArT. XXXIX.—Three Formations of the Middle Atlantic Slope; by W. J. McGrz.* (Continued from page 388.) Résumé.—The Columbia formation consists of a series of subestuarine and submarine deltas and associated littoral de- posits, occupying the entire Coastal plain of the Middle At- lantic slope up to altitudes ranging from about 100 feet in the south to over 400 feet in the north; the delta phase found at the mouths of the great rivers is bipartite, but the littoral phase overspreading the rest of the area is indivisible ; its ma- terials—which are derived lar gely from the Potomac formation and other local terranes and partly from the Piedmont and Appalachian regions—increase in coarseness northward, and_ are (in part) evidently ice-borne; it reaches greatest volume along the principal waterways and near the present coast ; it is destitute of fossils at high levels and in its lower (and ice- borne) portion, but at lower levels and higher horizons yields remains of marine animals of recent and local species; it is connected with an extensive series of shore-lines and terraces ; * Plates VI and VII are issued with this number. The parenthetical clause in the second line of page 137 of this series should read which he is disposed to refer to the Jurassic. the Middle Atlantic Slope. 449 and the deposits and shore-lines alike pass beneath, and are manifestly far older than, the terminal moraine. The predominant and most significant phenomena of the formation are widespread stratified deposits and associated ter- races; and if deposits are ever proof of deposition, and if shore lines ever tell of shores, the Coastal plain of the Middle Atlantic slope was submerged beneath floe-bearing oceanic waters during the Columbia period. Synopsis of Earlier Studies—While the isolated deposits representing it have not been correlated hitherto, and while the chronologic and taxonomic relations of its parts were never elucidated by local observers, the formation has been defined, and its genesis recognized, by every geologist who has studied its area. W. B. Rogers was one of the first to locally discriminate the formation, and was also one of the last to discuss its rela- tions: he recognized it in eastern Virginia in 1835,* and in 1839 accurately diagnosed its principal characters and inferred that it was formed in an ocean subjected to strong tides and currents ;+ and in 1875 he described it as developed about Washington, discriminated it from the newer Mesozoic (Poto- mac) gravels, indicated the sources of the coarser materials, noted its increasing coarseness northward, reiterated his infer- ence that it represents a period of submergence sufficient to fill the valleys and perhaps flood the divides of the Coastal plain, and inferred further that it was formed during a period of cold and floating ice probably coeval with the ice period of the north. H. D. Rogers recognized the formation in New Jersey in 1836, and inferred that the “sand and gravel” of which it consists was of sub-aqueous origin ;§ and he maintained the same inference in 1840.| In 1841 Booth discriminated the formation in southern Del- aware, enumerated its fossils, recognized its marine origin, and referred it to the “ after-Tertiary age. ’4] About the same time Conrad classified the later Tertiary deposits of the Middle Atlantic slope,** described various ex- posures of the stratified beds of the Columbia formation and enumerated their marine fossils (which are all of recent and local species), and referred them to the‘ Pleistocene or post- Pliocene.” * Geology of the Virginias, 1884. 29-30. + Ibid., 253, 264, 275. + Ibid., 709-13. § Report Geol. Survey of N. J., 2d ed., 1836, 17. || Description of the Geology of N. J., 1840, 176. 4| Mem. Geol. Survey Del., 1841, 94, 97. ** Bull. of Proceedings of Nat. Inst. for Promotion of Sci., i841, 177, et seq. 450 W. J. McGee—Three Formations of Mather recognized the formation on Long Island in 1843, enumerated its fossils, referred it to the “ Long Island divis- ion” of the “upper secondary system,” * attributed it to a marine current flowing northward “along the eastern coast,” and inferred from the paucity of organic remains and the presence of ice-borne blocks that the temperature was low during its deposition. The formation attracted Lyell’s attention during his two visits to this country: During the earlier he referred to the ‘‘ post-Pliocene ” “the marine shells” of eastern Georgia and South Carolina, which “ differ in no way from those of the ad- joining sea,” “contained in deposits of clay and sand ” over- lain in some places by dark colored clays yielding “remains of quadrupeds of extinct species ;” and concluded that at the time of deposition the land stood lower than now, while the temperature of atmosphere and ocean were little different from to-day.t During the later he discriminated the “low region bordering the Atlantic” from southern Georgia to the Neuse River in North Carolina, and made up of stratified sands and clays yielding recent marine shells from the terraces of Eocene deposits by which it is overlooked—the low plain rising but ten to forty feet above tide and extending only twenty miles inland. A few years later Tuomey described the same deposit in South Carolina as “sand, clay and mud, containing fossils, some sixty feet thick,” rising eight feet above tide and ex- tending only eight or nine miles inland,§ enumerated its fos- sils—which are all marine and nearly all recent and local,|— and referred it to the post-Pliocene. The observations of Lyell and Tnomey are significant in that they indicate narrowing and lowering of the formation southward. In 1852 Desor reviewed the paleontology of the formation as developed from South Carolina to Sancoty Head and Point Shirley, noted that the fossils are “nearly all referable to liv- ing species” and that the deposit occupies only a narrow zone rising eighteen feet above tide in the south but widening greatly and reaching an altitude of 100 feet northward,4 and inferred not only that it is marine, but that the climate was “warmer than now when it was deposited. He classed the formation as post-Pliocene, and correlated it with the “ Lauren- tian” of Canada and New England. * Geology of N. Y., Part I, 1843, 246, 261-8, 274-5. + Quart. Jour. Geol. Soe.. vol. ii, 1846, 405-6. t Second Visit to the U.S., N. ¥. 1855, vol. i, 256-61; vol. ii, 197. §$ Geology of South Carolina, 1848, 186, 188, 212. || Tbid., 203-5. § This Journal, IT, 1852, 50-3; ec. £, Proc. Boston Soc. Nat. Hist., I], 1851, 79; Mem. Boston Soc. Nat. Hist., 1866-9, 252. the Middle Atlantic Slope. 451 In 1860 Tyson described the formation as “ beds of loamy clays and sands” (supposed to rise only thirty feet above tide, but represented on the map over areas of much greater alti- tude) containing a few marine fossils and covering a consider- able portion of peninsular Maryland, concluded that “it con- sists of sediments derived from” the adjacent Piedmont and Appalachian regions, and referred it to the post-Tertiary.* In 1867 Sanderson Smith pointed out that the gravel and sand beds rising fifteen or twenty feet above tide on Gardiner’s Island contain twenty-five species of fossils, of which all but two now inhabit the Atlantic waters south of Cape Cod—the general facies of the fauna indicating a lower temperature than the present, and thus disproving Desor’s hasty inference of warmer climate.t Verrill more recently enumerated about sixty marine species (of which nearly all are recent and found in the immediate vicinity) from the petrographically similar and paleontologically equivalent deposits of Sancoty Head, of which those from the lower strata indicate warmer and those from the upper strata colder climate than the present—the dif- ference being attributed to local geographic changes. In 1868 Cook described the formation as clean quartz peb- bles and sand, covering the whole of peninsular New Jersey up to altitudes of 300 or 400 feet,§ designated it ‘“ Drift Gravel,” mentioned the ‘ deltas’? and “terraces” of which it is in part composed, and inferred not only that it is subaque- ous but also, from walrus remains within it, that the period of deposition was cold.| Ten years later he designated it “ Yel- low Sand and Gravel,’ pointed out that it is overlain by, and distinct in material and structure from, the modified and un- modified drift connected with the terminal moraine, and (find- ing difficulty in ascertaining the source of the materials) sug- gested that “it is a wash or drift from lands now under the ~ waves of the Atlantic.”** In 1880 he described the deposit in detail, designated it “ Preglacial Drift,” showed that it is un- conformable to the glacial drift above and the Cretaceous below,t+ and repeated his inference (but only as a “ possible hypothesis ”’) that it “was the wash from land to the southeast and now buried beneath the ocean, and took place in the later Tertiary age ;’++ and in 1884 he figured a bowlder of it, ten tons or more in weight, imbedded in the glacial drift.$$ In 1868 Cope recorded reindeer antlers from the gravels of * First Rep. State Ag’l Chemist of Md., 1860, 44. + Ann. Lye. Nat. Hist., N. Y., viii, 1867, 149-51. { This Journal, III, x, 1875, 364-9. § Geology of New Jersey, 227, 298, 242. || Tbid., 285-342. “| Report on Clays, 1878, 17. ** Tbid., 20. tt Report Geol. Survey of N. J., 1880, 87. tt Ibid., 95, 96. S$ Report Geol. Survey of N. J., 1884, 16-17. 452 - W. J. McGee—Three Formations of the formation in New Jersey, and enumerated other mammalia of the “terrace epoch” apparently from the same deposit (at least in part), including Hlephas promigentus, Mastodon gigan- teus, Equus ‘Fraternus, LE. complicatus, Dicotyles nasutus, Cer- vus Virginiana and C. canadensis.* In 1875 Kerr combined and referred to the Quaternary or post-Phocene a succession of clays, sands, gravels, ete., cover- ing the Coastal plain in North Carolina up to 500 feet above tide, and classified them as “ Glacial,’ “Champlain” and “ Terrace,’+ finding evidence of sub-aqueous deposition (1) in structure, (2) in “littoral and estuary shells undistinguishable specifically from those now living along the shore,’+ and (8) in terraces,§ and of coeval refrigeration (1) in bowlders and (2) in indications of soil-cap movement.| Further investigation led him to divide the deposits into Hocene{{ and undoubted Quaternary, the latter rising about 100 feet above tide at Wel. don and elsewhere in the northern part of the State, but in- clining southward nearly to sea level on Cape Fear River; and he inferred from the presence of the deposits, their struc: ture, and their fossils of recent marine species, as well as the terraces, that the formation was laid down during a Quaternary submergence “to the extent of probably 200 feet” on the Roa- noke, but diminishing to only a few feet in the southern part Ofithe State:.** Kerr’s later work is important in that it harmonizes and ex- tends that of W. B. Rogers and others in Virginia, and that of Lyell and Tuomey in South Carolina. In 1879 Fontaine incidentally noted certain characters of the formation, mentioned its unconformity to the Mesozoic and Tertiary deposits, recorded its presence along the Potomac, James, and Roanoke rivers up to altitudes of 60 feet, and concluded that at least a part of it was deposited during the Glacial period by aqueo-glacial agencies. ++ In 1880 Lewis separated the superficial deposits of Philadel- phia into (1) Brick Clay, (2) Red Gravel, (8) Black Gravel, (4) Yellow Gravel or Philadelphia Gravel, (5) Micaceous Sand, and (6) Bowlders ;{{ and later in the same year he combined the second and third, and apparently the fifth and sixth, of these divisions under the name of “Philadelphia Red Gravel, fc which he referred to the Champlain, and identified the “ Yel: low Gravel” of New Jersey with the fourth division (then * Geology of New Jersey, 1868, 740. + Hered eco ear yey of North Carolina, i, 1875, 154. t Ibid., § Ibid., 195 [misprint for 159. | | Ibid., 158. 4] The fees formation was not discriminated by Kerr, though it com- prises the greater part of the deposits described. ** Jour, Elisha Mitchell Scientific Society, 1884--5, Raleigh, 1885, 83-84. ++ This Journal, II], xvii, 1879, 42-3, 50, 54. tt Proe. Acad. Nat. Sci., Philad., vol. xxxii, 1880, 262. the Middle Atlantic Slope. 453 designated ‘Glassboro Gravel”), which he referred to the Pliocene.* The next year he concluded more specifically (1) that the Yellow Gravel of New Jersey ‘“‘is an ancient deposit of aqueous origin, made at a time of submergence in pre-glacial times ”;+ (2) that the Red Gravel was deposited by “an ancient flood of the [Delaware] river of great volume, at a time when it rose 100 or more feet higher than at present,” while the bowl- ders, the absence of life traces, and the altitude of the deposit “point to the melting of a great glacier as the origin of the - flood ;” and (3) that the brick clay with its contained bowlders represents the closing episode of the same submergence when quiet conditions prevailed ;—low temperature being again in- ferred from the absence of fossils and the presence of ice-borne bowlders.{ Still more recently the same author pointed out that the Brick Clay and Red Gravel rise to the northward in the Delaware and Lehigh valleys, maintaining a height of 180 to 200 feet above the rivers :§ and, assigning the Yellow Gravel to the newer Pliocene, supposed it to have furnished most of the pebbles of the Red Gravel.| In northern Delaware the Philadelphia Brick Clay and Red Gravel of Lewis were found by Chester to merge southward, and he combined them under the name ‘“ Delaware Gravels,”4 and inferred that they represent an epoch of land-submergence and melting glaciers Subsequently he described the gravels, sands, clays, etc., of the same formation in southern Delaware, identified them with those mentioned by Booth, noted the occurrence of recent marine shells within them, designated the deposit “ Estuary Sands,”** and demonstrated from stratigraphic continuity, from petrography, and from paleontology, that it is simply the peripheral extension of that which toward its center is divisible into Brick Clay and Red Gravel. ; Merrill has recently described and correlated the formation as found in peninsular New Jersey and on Long Island. He regards the New Jersey deposit as post Pliocene (since it over- lies unconformably “all the Mesozoic and known Tertiary beds, and is immediately overlain in turn by the glacial drift where it occurs south of the moraine”),t++ and identifies it with the stratified deposits of Gardiner’s and Long Islands; and on Long Island he discriminates (1) the Till or Drift proper and (2) the Gravel Drift—identifying the latter with the Yellow Drift or Pre-glacial drift of southern New Jerseytt and noting * Proc. Acad. Nat. Sci. Philad., vol. xxxii, 1880, 296-7. + Antiquity and Origin of the Treuton Gravels, appended to ‘“ Primitive Indus- try” by Abbott, 1881, 524. + Thid., 525, 527. $ Journal Franklin Institute, xev, 1883. 369. || Ibid., 371. “| This Journal, ITI, vol. xxvii, 1884, 190-2, 199. ** This Journal, III, vol. xxix, 1885, 40. ++ Official! Report Geol. Survey of N. J., 1886, 133. tt Annals N. Y. Acad. of Sci., iii, 1886, 343. “ 454 W. J. MeGee—Three Formations of the unconformable superposition of the former upon it,—enu- merates the fossils from the older deposits, and on their testi- mony refers it to the post-Pliocene and correlates it with the fossiliferous beds of Sancoty Head, and concludes that it was “formed by swift currents which carried along fine and coarse deposits together.”’* In 1884 Britton pointed out (1) that the Yellow Gravel of Staten Island and adjacent New Jersey is “a water deposit known to underlie the glacial drift,” masses of it being ‘im- bedded in the moraine,” and (2) that it reaches altitudes of 200 feet,t while the terraces connected with the terminal moraine rise only 25 or 30 feet above tide.t. He subsequently followed Cook in designating the formation “ Pre-Glacial Drift,” noted that it ‘‘is distributed along the Atlantic Border, from the coasts of the Southern States northward to the moraine, which it underlies unconformably,”’ mentioned its unconformity to the Miocene, enumerated the fossil plants (mostly recent and local) obtained from it at Bridgeton, N. J., and inferred (1) that it is “later Pliocene or Pleistocene” in age, and (2) that “a considerable amount if not the greater part” of the deposits “may well have come from the erosion of the Cretaceous gravel beds” along the Piedmont margin$—his enumeration and interpretation of the local phenomena being alike emi- nently satistactory. Reviewing the observations of these geologists, it appears (1) that the Rogers brothers, Booth, Conrad, Mather, Lyell, Tuomey, and Desor found a series of stratified sands and clays, containing recent marine shells, rising and expanding from a few feet above tide and a few miles in width in South Caro- lina, to over 100 feet in altitude, and scores of miles in width in the northern Coastal plain, the fauna being closely related to or identical with that of Gardiner’s Island, Sancoty Head, Shirley Point, and other obscure infra-moraine deposits along the New England coast; (2) that these deposits have been shown by W. B. Rogers, Tyson, Kerr and Chester, on the evi- dence of stratigraphic continuity, unity of structure, and iden- tity of terraces, to extend to the inland margin of the Coastal plain ; (8) that Chester has identified the phenomena and in some cases the localities described by Tyson and Booth, and shown that the brick clays and red gravels of the Delaware fall-line are stratigraphically continuous and homogenetic with the fossiliferous marine deposits recognized along the coast by the older geologists; (4) that Lewis has established the identity (in part) of the Philadelphia deposits with the gravels shown * Annals N. Y. Acad. Sci., iii, 1886, 354-8. + Proe. Nat. Sci. Assn. of Staten Island, Nov. 8, 1884. ¢ Ibid., April 10, 1886. § Trans. N. Y. Acad. Sci., iv, 1884-5 (1887), 26-33. the Middle Atlantic Slope. 455 by H. D. Rogers and Cook, to overspread peninsular New Jersey; (5) that the identity of the New Jersey gravels with the stratified deposits of Gardiner’s Island, Long Island, San- eoty Head and Shirley Point has been satisfactorily shown upon paleontologic grounds by Desor, Sanderson Smith, Verrill, Merrill and Britton; and (6) that the series of deposits has been shown by Cook, Merrill, Britton and others, to pass be- neath the terminal moraine and its derivatives. In short, col- ligation of all recorded observations indicates that the entire Coastal plain of the Middle Atlantic slope is occupied by a series of stratified deposits, abounding in bowlders and coarse gravel along the fall-line and bearing recent marine fossils toward the coast, which are overlain unconformably by the terminal moraine in the north. Reviewing the inferences of the same students as to the genesis and age of the formation it appears (1) that all consider it subaqueous; (2) that the Rogers brothers, Booth, Conrad, Mather, Lyell, Tuomey, Desor, 'l'yson, Sanderson Smith, Ver- rill, Cock, Kerr, Chester, Merrill, Britton, and perhaps others hold it to be marme; (8) that W. B. Rogers, Sanderson Smith, Cook, Cope, Kerr, Fontaine, Lewis, Chester, and others be- lieve it was deposited during a period of low temperature; (4) that all refer it, wholly or in part, to the later Tertiary or Quaternary; and (5) that Cook, Merrill and Britton regard it as pre-glacial. The several observations and inferences are in accord with those recorded above, and are here generalized only to corrob- orate conclusions reached independently after personal study (chiefly along the inland margin of the formation) in North Carolina, Virginia, the District of Columbia, Maryland, Dela- ware, Pennsylvania, New Jersey and New York. Taxonomy.—Vhe local relations.—By stratigraphic position and paleontology the Columbia formation is proved to be newer than any of the recognized Tertiaries of the Middle Atlantic slope, and its fauna is of modern facies. It therefore appears to be Quaternary or Pleistoeene in age. By (1) stratigraphic relations, (2) amount of erosion, and (8) degree of alteration, the formation is proved to be much older than the terminal moraine or the drift sheet whose margin it marks : 1. In the valleys of the Susquehanna and Delaware the ter- minal moraine is superimposed upon Columbia terraces and in part composed of Columbia materials; and similar relations have been repeatedly observed in New Jersey by Cook, on Staten Island by Britton, and on Long Island by Merrill. 2. A rough quantitative measure of the relative antiquity of the two deposits is found in the erosion they have suffered. 456 W. SJ. MceGee—Three Formations of On the upper Susquehanna the post-Columbia and pre-moraine erosion sufficed to excavate a valley from one to two miles wide and 200 feet deep, while the post-moraine erosion has scooped out a valley only a quarter of a mile wide and less than 100 feet in average depth; and similar relations obtain on the upper Delaware. Along the fall-line the post-Columbia erosion is measured by the gorges of the rivers between their falls and their embouchures into estuaries, just as the post- moraine erosion is measured by the gorges of the drift-covered area; and the Potomac and the Niagara are among the most sat- isfactory of these chronometers. Now since the emergence of the land from the Columbia ocean, the falls of the Potomac have receded through an obdurate terrane from West Washington to Great Falls, a distance of fifteen miles, while the Niagara, under conditions favoring gorge excavations, has receded only seven miles since the last ice-sheet withdrew beyond its lati- tude; and the contrast is still more striking in scores of other cases. The difference is exemplified by the smaller streams as well as by the larger, and equally by the minor topographic configuration—the hydrography of the Columbia being ma- ture, while that of the superimposed drift is nascent, and the Columbia surfaces being everywhere deeply furrowed and of ancient aspect, while the drift and Champlain surfaces are relatively little touched by time. In short, when post-moraine erosion is measured in yards, post- Columbia erosion must be measured in rods. 3. The moraine is seldom completely oxidized and lixiviated, and its rocks are seldom disintegrated; but where equally ex- posed the Columbia deposits are profoundly oxidized, lixiy- iated and ferruginated, and most of its non-siliceous rocks aré disintegrated, while the materials are frequently cemented not only by ferruginous but also by siliceous and calcareous matter. The widely diverse degrees of alteration in the two deposits everywhere serves as a criterion by which they may be distin- guished. In brief, the various phenomena of the Columbia formation proves that while it represents an epoch of cold and submer- gence, it is many times as old as the moraine-fringed drift by which it is unconformably overlain. It is noteworthy, too, that the volume of Columbia deposits is several times greater than the volume of corresponding deposits of the later ice- epoch, indicating that the earlier refrigeration was much the longer; and it is equally noteworthy that the later drift over- laps far upon the earlier aqueo-glacial deposits, indicating that the later cold was the more intense. _ The general relations.—A presumably complete sequence of Quaternar y deposits and of the events they represent has been the Middle Atlantic Slope. 457 made out in the Great Basin. In 1878 Gilbert described the sediments of the extinct lake Bonneville, recorded the infer- ence that the prevailing arid climate of the Great Basin was in- terrupted by a period of humid climate during which its moun- tain-enclosed basins were flooded and the lacustral sediments of Bonneville deposited, and correlated the humid epoch with that of northern glaciation ;* and he subsequently pointed out that the humid epoch was brief and apparently “an episode occurring in the later part of a long period of aridity.”+ In 1878, King called attention to the sediments and chemical pre- cipitates of the ancient lake Lahontan, and, avoiding detailed discussion of the former, conceived the latter phenomena to record (1) flooded and free-drained condition of the lake-basin, (2) shrinking and concentration of the waters and final desicea- tion of the basin with formation of the precipitate gaylussite, (3) re-flooding of the basin for along period during which the soluble salts were washed away and the gaylussite changed into thinolite by pseudomorphosis, and (4) partial desiccation pro- ducing present conditions. This sequence was regarded as partly coincident with and partly supplementary: to that deduced by Gilbert from the Bonneville phenomena; it was inferred that there was “a period of humidity anterior to Gil- bert’s earliest age of dryness” which was “enormously longer than [the period of humidity] in the second age of desicca- tion ;’ and the first of these humid periods was correlated with “the earliest and greatest Glacier period,” and the second with “the later Reindeer Glacier period.”t Gilbert later found évidence in the sediments of the Bonneville basin not only of a long humid period antedating that previously recognized but also of a much longer arid period preceding it, and concluded that the sequence of deposits represents a climatic sequence of “two humid maxima separated by an interval of extreme aridity,” the second humid maximum being the more pronounced and the first the longer.§ Still later and after extended investiga- tion, Russell found the sediments and precipitates of lake La- hontan to yield alike a record coincident with that of the Bon- neville deposits, save that the intermediate epoch of aridity was lengthened and some minor vicissitudes were introduced. He ascertained from the continuity of shore-lines and other evidence, however, that Lahontan did not overflow during * Bull. Philos. Soc. of Wash., vol. i, 1874, 84-85; Progress Rep. Geog. and Geol. Surveys West of 100th Merid., for 1872, 1874, 49-50. + Rep. Geog. and Geol. Surveys West of 100th Merid., vol. iii, Geology, 1875, 96-97. U.S. Geol. Expl. 40th Parallel, vol. i, Systematic Geology, 1878, 522-4. § Second Annual Rep. U. 8. Geol. Survey, 1880-1, 1882, 186-200. || Third Ann, Rep. U.S. Geol. Survey, 1881-2, 1883, 221-231: and Monograph U. 5. Geol Survey, vol. x, Geol. History of Lake Lahontan, 1885, 261-263. 458 W. J. McGee—Three Formations of either flood stage, and_read from the precipitates a record of (1) flooded condition of the basin without free drainage, (2) shrinking and concentration of the waters and precipitation of lithoid tufa (which was overlooked by King), (3) spasmodie reflooding of the basin and successive precipitation of (a) the mineral now pseudomorphosed into thinclite and (6) dendritic tufa (also overlooked by King), and (4) shrinking of the waters to below present level, followed by a slight re-advance.* This sequence of events is quite inconsistent with that deduced by King, and it thus appears that the coincidence in interpretation of the Lahontan precipitates by King and Russell respectively is no more than curiously fortuitous, and adds nothing to the weight of opinion of either investigator nor to the reliability of the history inferred from other phenomena. But there is a definite sequence of deposits in the Great Basin indicating a definite sequence of events (and the testimony of these deposits is corroborated by the shore-lines and by the precipitate as interpreted by Russell), viz: (i) basal gravels, representing long-continued arid climate; (2) lower lacustral beds; (8) medial gravels; (4) upper ‘lacustral beds ; ; and (5) recent gravels, ete. ; and the two lacustral periods are correlated by Gilbert and Russell with two vaguely defined periods of northern glaciation.t A fairly complete sequence of glacial and aqueo-glacial deposits in Iowa and northern Missouri affords a record of the early Quaternary history of the central Mississippi valley. It was pointed out by the writer in 1878, and again in 1879, that the bipartition of the glacial deposits and the intercalation of a forest bed within them in Iowa indicate two ice invasions separated by a long interglacial period ;{ in 1880 it was made known that the lower glacial deposit (or till) graduates upward into a series of stratified clays and extends much farther south- ward than the upper, which is associated with or graduates upward into loess;$ in 1882 it was shown that the loess is overlain by a third drift sheet, probably connected with the terminal moraine ;| and recent investigations have shown that the stratified upper member of the lower till (locally known as “oumbo”) not only bears unmistakable structural evidence of aqueous deposition but exhibits in its topographic configura- tion evidence of submergence of an extended area in Nebraska, * Op. cit. (2), 236. + While the lacustral deposits of the Great Basin are regarded as Oneismest by every stratigraphist and physical geologist who has investigated the subject, they have’ been referred to the Tertiary upon paleontologic grounds by Cope (Am. Naturalist, vol. xxi, 1887, 458-9) and perhaps others. } This Jour., III, vol. xv, 1878, 339-41; Proc. Am. Ass’n for Adv. of Sci, vol. xxvii, 1878, 198-231; Geol. Magazine, N. S., vol. vi, 1S 12) 353-361, 412-420. § Trans. Iowa Hort. Society, 1880. | This Journal, II, vol. xxiv, 1882, 222. the Middle Atlantic Slope. 459 Kansas, Missouri, southern Iowa, Illinois, Indiana and south- western Ohio, and indeed appears to be a continuation of the Port Hudson formation of the lower Mississippi as defined by Hilgard, thus indicating that during the earlier period of cold the central Mississippi valley was submerged—the far greater antiquity of the earlier till and “gumbo” than of their later homologues (the upper till and loess) being indicated by the intervening forest bed, by the greater disintegration and ferru- gination of the older materials and by the far greater degrada- tion beyond the limits of the newer deposits,* while there is much less indication of considerable lapse of time after the deposition of the loess and before the deposition of the super- jacent moraine-fringed drift-sheet. So the Iowa-Missouri sequence in historic order is, (1) first glacial drift (basal till) passing upward into waterlaid clays with erratics (“gumbo”), (2) great unconformity and forest bed, (8) second till passing upward into or overlain by loess, (4) inconspicuous unconfor- mity, and (5) third till apparently connected with the terminal moraine. The glacial phenomena of Northern United States have been elaborately investigated by Chamberlin and found to contain a definite record of the events constituting the glacial history of the continent. His allocation of leading episodes in the his- toric order is as follows: Epochs. Subepochs or episodes. Attendant or characteristic phenomena. J. Transition epoch. Not yet satisfactorily distinguished from the Pliocene. ( Drift sheet with attenuated bor- der; absence or meagerness of coarse ultra-margimal drainage drift. Decomposition, oxidation, ferru- gination; vegetal accumulation. First subepoch or oe | ( Drift sheet with attenuated bor- 4 ( | sode. IL Earlier gla- fallepoch + Interglacial subepoch or episode of glaciation. Second subepoch or epi- der; loess contemporaneous lg Soule: with closing stage. Elevation of the Upper Mississippi region 1,000 + feet. Erosion of WT, Chief interglacial epoch...._.----___- + old drift, decomposition, oxida- | tion, ferrugination, vegetal accu- mulations (First episode or sub- { Till sheet bordered by the Kettle epoch. ( or Altamont moraine. Episode of deglaciation. Vegetal deposits 1 Second stage or subepoch. ae sheet bordered by the Gary j IV. Later glacia moraine. epoch. |} Episode of deglaciation. 5 - hirdvepicodel oes. § Till bordered by the Antelope mo- { raine. : { Marked by terminal moraines of (pate SUBES 2oc saan: } undetermined importance. * Trans. St. Louis Academy of Sciences (in press). Am. Jour. Sci.—THirpD SERIES, Vor. XXXV, No. 210.—JUNE, 1888. 4 460 W. J. MceGee—Three Formations of Epochs. Attendant or characteristic phenomena. { Marine deposition in the Cham- | plain and Saint Lawrence val- We Clagyayalentn, Chyoeoy sooo A oe 4 leys and on Atlantic border; | lacustrine deposits about the | Great Lakes. {Marked by fluvial excavation, WAL ANAROS GNOO MN os Sosa ood Soto naeee= { notably of the flood plains of {| second glacial epoch. When juxtaposed, the Middle Atlantic slope and Great Ba- sin sections are exactly coincident, save (1) that the Cham- plain clays of the east are unrepresented in the west,-and (2) that the duration of the interglacial epoch appears the greater in the east; there is not only the same general succession of events (cold-wet, warm-dry, cold-wet, the whole preceded and followed by warm-dry), but in each case the earlier period of cold and wet was the longer and the cold and wet of the later the more intense; and since the climatic episodes attested by the phenomena in either case were so extreme as to indicate that they were continental in extent, the two series of deposits may safely be correlated. The discrepancies are insignificant, (1) becanse it is evident that the Champlain epoch of the east must have been represented in the west by simple continuation of preceding conditions, and (2) because the testimony as to the duration of the interglacial epoch is much more complete and satisfactory in the east than in the west. Difficulty is encountered in juxtaposing the Mississippi Val- ley section with the foregoing, since Chamberlin’s fruitful in-~ vestigations have convinced him that the longer interglacial epoch occurred posterior to the deposition of the loess and the till with which it is associated ; while the writer’s observations in Iowa, Missouri, and neighboring states indicate that the a-glacial epoch following the loess period was of limited length and represents only a temporary oscillation in the ice sheet, and that the interglacial period proper occurred anterior to the deposition of the second till and its associated loess. Under either interpretation, however, the section is fairly con- sistent with those of the Great Basin and Middle Atlantic slope; as interpreted by Chamberlin the short a-glacial epoch of the earlier period of refrigeration might well be regarded as indicating but a temporary oscillation of the ice sheet unaccom- panied by appreciable change in altitude or in conditions of aqueo-glacial deposition; while under the writer’s interpreta- tion the complexity of the later record is attributable chiefly to its accessibility and to the care with which it has been deci- phered, for, despite the greater number of divisions recognized in the later series, it is less important than the earlier as meas- ured either by volume of derived aqueo-glacial deposits or by the Middle Atlantic Slope. 461 ’ contemporaneous erosion. Space would not permit discussion of the data upon which the conflicting opinions rest, even if discussion were desirable ; but the difference of view is simply an effect of intellectual perspective which shows to each inves- tigator in exaggerated proportion the phenomena which he has most closely scrutinized, and will disappear with continued observation. The juxtaposed sections are exhibited in the accompanying table. It may be pointed out that the succession of deposit in the Mis- sissippi Valley, as interpreted in the third column of the table coincides almost exactly with the sequence recognized by Penck in the German Alps, where the succession in historic or- der is (1) glacial drift, (2) an enormous accumulation of torren- tial gravels, now commonly ferruginated, cemented and deeply eroded, (8) a second glacial deposit, (4) a less accumulation of torrential gravels, with alluvium, laminated clays, lignite, ete., and (5) a third glacial deposit, found only at considerable alti- tudes in the mountains.* Recapitulation.—In. short the Columbia formation under- lies and is several times older than the moraine-fringed drift- sheet of northeastern United States; it is apparently the aqueo- glacial margin of a drift-sheet largely concealed or obliterated in the northern Atlantic slope; it appears to be equivalent to the lower lake beds of the Great Basin, to the basal till and “oumbo” of Missouri, to (probably) the Port Hudson of Mis- sissippi, and to (perhaps) the lowest glacial deposits of the Alps; and while the vertebrates of its correlatives suggest that it is Pliocene, both stratigraphy and invertebrate fossils prove that it is Quaternary. It should be added that the conjoined phenomena of the Middle Atlantic slope and the Mississippi Valley indicate the respective areas of the earlier and later ice sheets: In the east the earlier extended the farther as shown by the superposition of the newer moraine upon the older aqueo-glacial deposits ; but whether the earlier glacier formed no moraine, whether there was an earlier moraine perhaps coincident with the drum- lin zone passing through central Massachusetts and New York, or whether the earlier drift was obliterated by the later glacia- tion, remains to be determined. In [owa, Missouri and south- ern Illinois, on the other hand, the earlier ice sheet. extended fully one hundred miles farther southward than the later, and, having evidently terminated in the waters of the expanded Gulf or of an inland lake, its limit is not marked by a terminal moraine. A hypothetic explanation of this diserepance, based * Die Vergletscherung der Deutschen Alpen, 1882, 239, Tabelle II, ete. g W. J. MceGee—Three Formations of 462 ‘HM O81 | (‘yaoda yor9n)b-0 4.10YS') | sseoTy J “poq 4so1oy TH PG (oyu Surssed) (‘ys0de ynwnjb-v Buoy) ‘IL PE pue oure.sout 7 fe ‘uywaqunyy fq payasdvaquy (g yooda ynran)b-» 4.L0YS)) ‘114 pE pur ouresou [euLMJay, ‘S[OARLO [BSVg “TU 981 C1 (oyut Sutssed) *‘Speq ov] JoMoT OQUINE) 55 (‘yooda yoranj6-» BuoT) (‘yooda ha) *poq ysa.loy ‘S[OABIS BIPOPW “I PZ | (oyu sutssed) Ssoo'T | r *spoq oye] sodd gq ne ‘sABlO ZISSVS VY O\e'T aay on fg poyasdiajuy “AUTTV A Idd ISSISSIJ ‘NISVG LVAU+) “‘pnuaUmouayg hupusaqnn(yy upowawp fo snyoodsuog IOMO] OFUL paRMTQALOU Suissed 4) TOTYVUAO} VIGUUNTORH (‘yoda youmb-n Buoy) ‘T174 soddpy puv ouresour [eULooy, ‘sAvyo UreydaueryD ‘AdOTS OLLNVILY AICI —— + -— — —- *B10BI.6 puodIEs *[BIOe |S ISILT *TeloRlo-1e}UT “HOOay the Middle Atlantic Slope. 463 on well-known phenomena of the respective regions, is not far to seek: In the east the ice was thick and moved energetically, .. ploughing up subjacent deposits and scoring subjacent rocks, * and quickly reached the line of equilibrium -between growth and waste corresponding to given temperature; while in the Mississippi Valley the ice was but a third or a quarter so thick and moved sluggishly, passing over hundreds of square miles without removing the subjacent deposits or touching the sub- jacent rocks, probably failed to reach its line of equilibrium during the earlier, and certainly fell far short of it during the later and briefer refrigeration. The two ice-boundaries cross somewhere in Ohio. The History Recorded in the Columbia Formation.—The geologic history recorded in the Columbia deposits and_ter- races and in the erosion and alteration which both have suf- fered is almost wholly supplementary to that read by most geologists in the later glacial deposits, and multiplies many times the length of the Quaternary as commonly conceived. Collectively the two series of deposits indicate that the Quater- nary consisted of two and only two great epochs of cold (the later comprising two or more sub-epochs) ; that these epochs were separated by an interval three, five, or ten times as long as the post-glacial interval; that the earlier cold endured much the longer; that the earlier cold was the less intense and the resulting ice sheet stopped short (in the Atlantic slope) of the limit reached by the later; that the earlier glaciation was accompanied by much the greater submergence, exceeding 400 feet at the mouth of the Hudson and extending 500 miles southward, while that of the later reached but a tithe of that depth or southing ; and that during the long interglacial inter- val the condition of land and sea was much as at present. Moreover, as in the Potomac formation, geologic history is recorded not only in the formation itself but in its relation to the floor upon which it rests; and the history read from the deposits is thus materially supplemented. A remarkable topographic characteristic is displayed by the Piedmont and Appalachian regions in the middle Atlantic slope, which has only been interpreted—or indeed recognized. —within the decade. The entire area is but a gently undulating plain, diversified throughout by deeply incised waterways and, in the Appalachian zone, by bosses and ridges of obdurate strata which are narrowed and truncated by erosion but not planed off. The cross-section of the Susquehanna (fig. 1), with its gently undulating plain bounded by mountains and dissected by a steep bluffed gorge, is representative of the entire Appalachian zone; it is constantly repeated along each principal waterway of that zone, and—save that the bounding mountains are ab- ~ — 464 _W. J. McGee—Three Formations of sent—throughout the Piedmont region; and lines drawn in any direction through the area give ever-varying but harmoni- ous combinations of this profile. During recent years this peculiar configuration has attracted the attention of nearly all geologists who have worked in the area. Stevenson has attrib-. uted the broad intermontane plains of the Pennsylvania Ap- palachians to wave-action during, and their minor irregularities ie MONTOUR FIDGE CATAWISSA HILLS Cross-Section of Susquehanna Valley between Bloomsburg and Rerwick. to spasmodic elevation following, a general submergence, and ascribed the incised valleys to the action of the streams now occupying them during a recent epoch of high land;* Kerr attributed the corresponding plains of the Piedmont region in North Carolina to glacial action during a remote epoch ;f G. F. Wright ascribes certain of the plains along the western slope of the Appalachians to a temporary ice-dam in the Ohio Valley ;{ I. C. White recently referred the deposits upon these plains, if not the plains themselves, as exhibited along the Appalachian rivers, to submergence probably coeval with northern glaciation ;§ but Gilbert has pointed out (orally) that in Virginia and North Carolina, at least, the system of inter- montane plains represents an old base-level of erosion. The composite Appalachian profile indeed indicates clearly that at some period of the past the Piedmont-Appalachian area stood low until the rivers, their affluents, the rivulets leading into these, and even the minutest rain-born rills, cut their channels to base level and planed all the rocks except the obdurate quartz- ites and sandstones to the same level; and that afterward the land was lifted until the waters attacked their channels, cut out the labyrinth of recent gorges, and reduced the valleys, but not the hills, to a new base-level This degradation-record is as definite and reliable as any found within deposits; and while so little is known of the physical relations of the clastic deposits of the Coastal plain (though they have been system- atically classified repeatedly upon other bases) that they tell us less than the Piedmont hills of the evolution of the continent, * Proc. Am. Philos. Soc., vol. xvii, 1879, 315-316. + This Journal, III, vol. xxi. 1881, 216-19. { Am. Nat., xvili, 1884, 563-7. § This Journal, III, xxxiv, 1887, 374-81. the Middle Atlantic Slope. 465 and while it is yet impossible for that reason to correlate the records of land and sea, it will eventually be shown that the broad base-level plain corresponds to an important marine for- mation somewhere in the Coastal plain series. The uncon- formity in deposits corresponding to the rise of land closing the base-level period has not been certainly identified, but it seems probable that the deep and broad estuaries of the Coastal plain were then excavated, or at least deepened; and’ their depth suggests that for a time the land stood higher than now.* The Columbia formation reposes upon the less elevated por- tion of the Piedmont-Appalachian base-level plain and within the newer gorges dissecting it, as well as upon the Coastal plain and within its estuaries to considerable depths (generally undetermined but known to exceed 140 feet in Chesapeake Bay). It is evident from the relations of deposit to sub- terrane in the Piedmont region that the deposition of the for- mation occurred long posterior to the rise of the land by which the old base-level was disturbed ; for despite the high declivity of the stream post-Columbia erosion has not sufficed to lay bare the bottom of the pre-Columbia gorge or to remove more than half or two-thirds of the Columbia deposits in the Sus- quehanna and Delaware Valleys; and the post-Columbia ero- sion of the Potomac is measured by a gorge but 15 miles long, half a mile wide, and 75 feet in average depth, while the post- base-level erosion is represented by an outer gorge more than 200 miles long, over a mile in width, and fully 200 feet in average depth, and by corresponding gorges extending to the very sources of all its tributaries. Indeed, when post-glacial erosion is measured in yards and post-Columbia erosion in rods, post-baselevel erosion must be measured in furlongs if not in — miles. So the direct record of the Columbia formation goes back to an era 3, 5, or 10 times as remote as that to which the Quater- nary has commonly been carried, while its indirect record ex- tends far into the Tertiary and affords part of the data required for equilibrating Tertiary and Quaternary time—the data from the deposits being yet lacking. * Tt should be noted that, as indicated by rapid corrasion on the one hand and the failure of equally rapid deposition to fill the estuaries on the other hand, the Piedmont region is now rising, while the Coastal plain is sinking—the displace- ment coinciding with the fall line; that this movement has been in progress since the Columbia period at least; and that in consequence the records of continental oscillation found on opposite sides of the fall line are inconsistent. There is evi- dence, too. that the hydrography of the Coastal Plain, and especially the deflection of the rivers at the fall line, was determined during the Columbia period; and hence that the estuaries were cut not by the rivers which occupy them but by those which more nearly coincide with their courses. 466 W. J. McGee—Lormations of the Atlantic Slope. The vicissitudes recorded in the Columbia formation and associated phenomena may be graphically represented as in the accompanying diagrams. It should be pointed out that the earlier part of the record is shadowy, that the quantitative esti- mates are but roughly approximate, and that the later part of the record is obscured by the fall-line displacement (which can- not be here discussed); yet the graphic interpretation of the 2. TERTIARY QUATERNARY SS eee PRE- ier 2"°83" POST GLACIAL GLACIAL INTER - GLACIAL GLACIAL GLACIAL pass aL eh ; ’ . Degragation : 1 Degradation ; (nan Depradation ohh LR Ee RE seston $s Degradation : : - ALTITUDE CURVE TEMPERATURE CURVE e 1 Deposition of Columbia Formation. 2 Deposition of Trenton Gravels and Champlain Clays. 3 Accelerated Degradation dueto Human Activities later episodes (fig. 2) is reliable qualitatively, though the rela- tions between these episodes and the more important antece- dent vicissitudes is only represented provisionally (fig. 3). 3, TERTIARY QUATERNARY => BASE-LEVEL PERIOD PERIOD OF PIEDMONT ~ APPALACHIAN GORGE CUTTING 1234 —<—$——SSSSeSe 1 1'Glacial Period 2 Inter-glacial Period 3 2 and 3% Glacial Periods 4 Pust-Glacial Period There is a break in geologic history, as commonly inter- preted, between the Tertiary and the Quaternary—a_ hiatus partly natural and partly taxonomic, and exceedingly difficult to close by reason of diverse methods of classification as well as by reason of the dearth of common phenomena. But the formation under consideration is a superficial deposit of known genesis, intimately connected. with the other Quaternary de- posits of the country; it is at the same time a fossiliferous sedimentary deposit as intimately connected with the Tertiary formations of the middle Atlantic slope as these are connected among themselves ; and thus the formation not only covers the natural discontinuity between the Tertiary and Quaternary, but, since it is susceptible of classification with either, closes the taxonomic hiatus as well. So the Columbia formation not only enlarges current conceptions of Quaternary time, and opens a hitherto sealed chapter in geology, but at the same time bridges an important break in geologic history. J. W. Gibbs—EHlastic and Electrical Theories of Light. 467 Art. XXXIV.—A Comparison of the Elastic and the FHlec- trical Theories of Light with respect to the Law of Double Refraction and the Dispersion of Colors; by J. WILLARD GIBBS. Ir is claimed for the electrical* theory of light that it is free from serious difficulties, which beset the explanation of the phenomena of light by the dynamics of elastic solids. Just what these difficulties are, and why they do not occur in the explanation of the same phenomena by the dynamics of electri- city, has not perhaps been shown with all the simplicity and generality which might be desired. Such a treatment of the subject is however the more necessary on account of the ever- increasing bulk of the literature on either side, and the confus- - ing multiplicity of the elastic theories. It is the object of this paper to supply this want, so far as respects the propagation of plane waves in transparent and: sensibly homogeneous media. The simplicity of this part of the subject renders it appropriate for the first test of any optical theory, while the precision of which the experimental determinations are capable, renders the test extremely rigorous. It is moreover, as the writer believes, an appropriate time for the discussion proposed, since on one hand the experi- mental verification of Fresnel’s Law has recently been carried to a degree of precision far exceeding anything which we have had before,+ and on the other, the discovery of a remarkable theorem relating to the vibrations of a strained solid{ has given a new impulse to the study of the elastic theory of light. * The term electrical seems the most simple and appropriate to describe that theory of light which makes it consist in electrical motions. The cases in which any distinctively magnetic action is involved in the phenomena of light are so exceptional. that it is-difficult to see any sufficient reason why the general theory should be called electro-magnetic, unless we are to call all phenomena electro- magnetic which depend on the motions of electricity. + In the recent experiments of Professor Hastings relating to the index of refraction of the extraordinary ray in Iceland spar for the spectral line Dz and a wave-normal inclined at about 31° to the optic axis, the difference between the observed and the calculated values was only two or three units in the sixth decimal place (in the seventh significant figure), which was about the probable error of the determinations. See page 60 of this volume. ¢ Sir Wm. Thomson has shown that if an elastic incompressible solid in which the potential energy of any homogeneous strain is proportional to the sum of the squares of the reciprocals of the principal elongations minus three is subjected to any homogeneous strain by forces applied to its surface, the transmission of plane waves of distortion, superposed on this homogeneous strain, will follow exactly Fresnel’s law (including the direction of displacement), the three privcipal veloci- ties being proportional to the reciprocals of the principal elongations. It must be a surprise to mathematicians and physicists to learn that a theorem of such simplicity and beauty has been waiting to be discovered in a fiela which has been so carefully gleaned, See page 116 of the current volume (xxv) of the Philo- sophical Magazine. 468 J. W. Gibbs—Elastic and Electrical Theories of Light. Let us first consider the facts to which a correct theory must conform. It is generally admitted that the phenomena of light consist in motions (of the type which we call wave-motions) of some- thing which exists both in space void of ponderable matter, -and in the spaces between the molecules of bodies, perhaps also in the molecules themselves. The kinematics of these motions is pretty well understood; the question at issue is whether it agrees with the dynamics of elastic solids or with the dynamics of electricity. In the case of a simple harmonic wave-motion, which alone we need consider, the wave-velocity (V) is the quotient of the wave-length (/) by the period of vibration(p). These quantities can be determined with extreme accuracy. In media which are sensibly homogeneous but not isotropic the wave-velocity V, for any constant value of the period, is a quadratic function of the direction cosines of a certain line, viz: the normal to the so-called “ plane of polarization.” The physical character- istics of this line have been a matter of dispute. Fresnel con- sidered it to be the direction of displacement. Others have maintained that it is the common perpendicular to the wave- normal and the displacement. Others again would define it as that component of the displacement which is perpendicular to the wave-normal. This of course would differ from Fresnel’s view only in case the displacements are not perpendicular to the wave-normal, and would in that case be a necessary modi- fication of his view. Although this dispute has been one of the most celebrated in physics, it seems to be at length sub- stantially settled, most directly by experiments upon the scat- tering of light by small particles, which seems to show deci- sively that in isotropic media at least the displacements are normal to the “ plane of polarization,” and also, with hardly less cogency, by the difficulty of accounting for the intensities of reflected and refracted light on any other supposition.* It should be added that all diversity of opinion on this subject has been confined to those whose theories are based on the dynamics of elastic bodies. Defenders of the electrical theory * ‘(At the same time, if the above reasoning be valid, the question as to the direction of the vibrations in polarized light is decided in accordance with the view of Fresnel. . . . I confess I cannot see any room for doubt as to the result itleadsto. .. I only mean that 7light, as is generally supposed, consists of transversal vibrations similar to those which take place in an elastic solid, the vibration must be normal to the plane of polarization.” Lord Rayleigh ‘‘ On the Light from the Sky, its Polarization and Color ;” Phil. Mag. (4), xli (1871), p. 199. ‘‘Green’s dynamics of polarization by reflexion, and Stokes’ dynamics of the dif- fraction of polarized light, and Stokes’ and Rayleigh’s dynamics of the blue sky, all agree in, as it seems to me, irrefragably, demonstrating Fresnel’s original con- clusion, that in plane polarized light the line of vibration is perpendicular to the plane of polarization.” Sir Wm. Thomson, loc. citat. J. W. Gibbs— Elastic and Electrical Theories of Light. 469 have always placed the electrical displacement at right angles to the “plane of polarization.” It will, however, be better to assume this direction of the displacement as probable rather than as absolutely certain, not so much because many are likely to entertain serious doubts on the subject, as in order not to exclude views which have at least a historical interest. The wave-velocity, then, for any constant period, is a quad- ratic function of the cosines of a certain direction, which is probably that of the displacement, but in any case determined by the displacement and the wave-normal. The coefficients of this quadratic function are functions of the period of vibration. It is important to notice that these coefficients vary separately, and often quite differently, with the period, and that the case does not at all resemble that of a quadratic function of the direction-cosines multiplied by a quantity depending on the pericd. In discussing the dynamics of the subject we may gain some- thing in simplicity by considering a system of stationary waves, such as results from two similar systems of progressive waves moving in opposite directions. In such a system the energy is alternately entirely kinetic and entirely potential. Since the total energy is constant, we may set the average kinetic energy per unit of volume at the moment when there is no potential energy equal to the average potential energy per unit of volume when there is no kinetic energy.* We may call this the equation of energies. It will contain the quantities 7 and p, and thus furnish an expression for the velocity of either sys- tem of progressive waves. We have to see whether the elastic or the electric theory gives the expression most conformed to the facts. f Let us first apply the elastic theory to the case of the so- called vacuum. If we write 4 for the amplitude measured in the middle between two nodal planes, the velocities of dis- placement will be as bs and the kinetic energy will be rep- resented by ye where A is a constant depending on the den- sity of the medium. The potential energy, which consists in distortion of the medium, may be represented by Be, where B is a constant depending on the rigidity of the medium. The equation of energies, on the elastic theory, is therefore hi hi JN ] p if ( ) : : Ge B which gives Wise ee (2) x A * The terms kinetic energy and potential energy will be used in this paper to denote these average values. 470 J. W. Gibbs—Elastic and Electrical Theories of Light. In the electrical theory, the kinetic energy is not determined by the simple formula of ordinary dynamics from the square of the velocity of each element, but is found by integrating the product of the velocities of each pair of elements divided by the distance between them. Very elementary considerations suffice to show that a quantity thus determined when estimated per unit of volume will vary as the square of the wave-length. We may therefore set Feo for the kinetic energy, F being L a constant. The potential energy does not consist in distor- tion of the medium, but depends upon an elastic resistance to the separation of the electricities which constitutes the electrical displacement, and is proportioned to the square of this displacement. The average value of the potential energy per unit of volume will therefore be represented in the elec- trical theory by Gh*, where G is a constant, and the equation of energies will be . 2 h* 1Z2 @ Fe = Gh (3) which gives y /? G Via a= i) Both theories give a constant velocity, as is required. But it is instructive to notice the profound difference in the equations of energy from which this result is derived. In the elastic theory the square of the wave-length appears in the potential energy as a divisor; in the electrical theory it appears in the. kinetic energy as a factor. Let us now consider how these equations will be modified by the presence of ponderable matter, in the most general case of transparent and sensibly homogeneous bodies. This subject is rendered much more simple by the fact that the distances be- tween the ponderable molecules are very small compared with a wave-length. Or, what amounts to the same thing, but may present a more distinct picture to the imagination, the wave- length may be regarded as enormously great in comparison with the distances between neighboring molecules. Whatever view we take of the motions which constitute light, we can hardly suppose them (disturbed as they are by the presence of the ponderable molecules) to be in strictness represented by the equations of wave-motion. Yet in a certain sense a wave- motion may and does exist. If, namely, instead of the actual displacement at any point, we consider the average displace- ment in a space large enough to contain an immense number of molecules, and yet small as measured by a wave-length, such average displacements may be represented by the equations of - J. W. Gibbs—Elastic and Electrical Theories of Light. 471 wave-motion; and it is only in this sense that any theory of wave-motion can apply to the phenomena of light in trans- parent bodies. When we speak of displacements, amplitudes, velocities (of displacement), ete., it must therefore be under- stood in this way. The actual kinetic energy, on either theory, will evidently be greater than that due to the motion thus averaged or smoothed, and to a degree presumably depending on the direction of the displacement. _ But since displacement in any direction may be regarded as compounded of displacements in three fixed directions, the. additional energy will be a quadratic function of the components of velocity of displacement, or, in other words, a quadratic function of the direction-cosines of the displace- ment multiplied by the square of the amplitude and divided by the square of the period.* This additional energy may be understood as including any part of the kinetic energy of the wave-motion which may belong to the ponderable particles. The term to be added to the kinetic energy on the electric h* theory may therefore be written 7, —, where jf, is a quadratic function of the direction-cosines of the displacement. The elastic theory requires a term of precisely the same character, but since the term to which it is to be added is of the same general form, the two may be incorporated in a single term of the form Le where A, is a quadratic function of the direc- tion-cosines of the displacement. We must, however, notice that both A, and,f, are not entirely independent of the period. For the manner in which the flux of the luminiferous medium is distributed among the ponderable molecules will naturally depend somewhat upon the period. The same is true of the © degree to. which the molecules may be thrown into vibration, But A, and 7, will be independent of the wave-length, (except so far as this is connected with the period,) because the wave- length is enormously great compared with the size of the mole- cules and the distances between them. The potential energy on the elastic theory must be increased by a term of the form 6, h’, where 6, is a quadratic function of the direction-cosines of the displacement. Jor the ponderable particles must oppose a certain elastic resistance to the dis- placement of the ether, which in xolotropic bodies will pre- sumably be different in different directions. The. potential energy on the electric theory wil] be represented by a single term of the same form, say G, /*, where a quadratic function of the direction-cosines of the displacement, G,, takes the place * For proof in extenso of this proposition, when the motions are supposed electrical, the reader is referred to volume xxiii of this Journal, page 268. 472 J. W. Gibbs— Elastic and Electrical Theories of Light. of the constant G, which was sufficient when the ponderable particles were absent. Both G, and 4, will vary to some ex- tent with the period, like A, and.7,, and for the same reason. In regard to that potential energy, which on the elastic theory is independent of the direct action of the ponderable molecules, it has been supposed that in eolotropic bodies the effect of the molecules is such as to produce an eolotropie state in the ether, so that the energy of a distortion varies with its orientation. This part of the potential energy will then be represented by B,, a? where B,, is a function of the directions of the wave-normal and the displacement. It may easily be shown that it is a quadratic function both of the direction- cosines of the wave-normal and of those of the displacement. Also, that if the ether in the body when undisturbed is not in a state of stress due to forces at the surface of the body, or if its stress is uniform in all directions, like a hydrostatic pressure, the function B,, must be symmetrical with respect to the two sets of direction-cosines. The equation of energies for the elastic theory is therefore as lor Ab = Byo F aie bp he, (5) which gives Wi ie — nese : (6) p Ap—)p p” The equation of energies for i electrical theory is h? ey Sh for Gr) eae (7) which gives Gal. 2. 2 (8) It is evident at once that the electrical theory gives exactly the form that we want. For any constant period the square of the wave-velocity is a quadratic function of the direction- cosines of the displacement. When the period varies, this function varies, the different coefficients in the function vary- ing separately, because G, and f, will not in general be simi- lar functions.* If we consider a constant direction of displace- ment while the period varies, G, and 7, will only vary so far as the type of the motion varies, z. ¢., so far as the manner in which the flux distributes itself among the ponderable mole- * But G,, f», and V*, considered as functions of the direction of displacement, are all subject te any law of symmetry which may belong to the structure of the body considered. The resulting optical characteristics of the different crystallo- graphic systems are given in volume xxiii of this Journal, page 273. J. W. Gibbs—Elastic and Electrical Theories of Light. 478 cuies and intermolecular spaces, and the extent to which the molecules take part in the motion are changed. There are eases in which these vary rapidly with the period, viz: cases of selection absorption and abnormal dispersion. but we may fairly expect that there will be many cases in which the char- acter of the motion in these respects will not vary much with ot and ‘ = will then be sensibly constant and we have an approximate eae for the general law of disper- sion, which agrees remarkably well with experiment.* If we now return to the equation of energies obtained from the elastic theory, we see at once that 1t does not suggest any such relation as experiment has indicated, either between the wave-velocity and the direction of displacement, or between the wave-velocity and the period. It remains to be seen whether it can be brought to agree with experiment by any hypotheses not too violent. In order that V* may bea pee function of any set of direction-cosines, it is necessary that A, and 0, shall be inde- pendent of the direction of the displacement, in other words, in the case of a crystal like Iceland spar, that the direct action of the ponderable molecules upon the ether, shall affect both the kinetic and the potential energy in the same way, whether the displacement take place in the direction of the optic axis or at right angles to it., This is contrary to everything which we should expect. If, nevertheless, we make this supposition, it remains to consider B,,. This must be a quadratic function of a certain direction, which is almost certainly that of the dis- placement. If the medium is free from external stress (other than hydrostatic), B,,, as we have seen, is symmetrical with respect to the wave-normal and the direction of displacement, and a quadratic function of the direction-cosines of each. The only single direction of which it can be a function is the com- mon perpendicular to these two directions. If the wave- normal and the displacement are perpendicular, the direction- cosines of the common perpendicular to both will be linear functions of the direction-cosines of each, and a quadratic function of the direction-cosines of the common perpendicular will be a quadratic function of the direction-cosines of each. We may thus reconcile the theory with the law of double re- fraction, in a certain sense, by supposing that A, and b, are independent of the direction of displacement, and that b,, and therefore V* is a quadratic function of the direction-cosines of the common perpendicular to the wave-normal and the dis- the period. * This will appear most distinctly if we consider that V divided by the velocity of light mm vacuo gives the reciprocal of the index of refraction, and » multiplied by the same quantity gives the wave-length in vacuo. 474 J. W. Gibbs—EHlastic and Electrical Theories of Light. placement. But this supposition, besides its intrinsic improb- ability so far as A, and 6, are concerned, involves a direction of the displacement which is certainly or almost certainly wrong. | We are thus driven to suppose that the undisturbed medium is in a state of stress, which, moreover, is not a simple hy- draulic stress. In thiscase, by attributing certain definite phy- sical properties to the medium, we may make the function B,, become independent of the direction of the wave-normal, and reduce to a quadratic function of the direction-cosines of the displacement.* This entirely satisfies Fresnel’s Law, including the direction of displacement, if we can suppose A, and 4, in- dependent of the direction of displacement. But this supposi- tion, in any case difficult for aeolotropic bodies, seems quite irreconcilable with that of a permanent (not hydrostatic) stress. For this stress can only be kept up by the action of the pon- derable molecules, and by a sort of action which hinders the pas- sage of the ether past the molecules. Now the phenomena of reflection and refraction would be very different from what they are, if the optical homogeneity of a crystal did not extend up very close to the surface. This implies that the stress is produced by the ponderable particles in a very thin lamina at the surface of the crystal, much less in thickness, it would seem probable, than a wave-length of yellow light. And this again implies that the power of the ponderable particles to pin down the ether, as it were, to a particular position is very great, and that the term in the energy relating to the motion of the ether relative to the ponderable particles is very important. This is the term containing the factor b,, which it is difficult to sup- pose independent of the direction of displacement because the dimensions and arrangement of the particles are different in different directions. But our present hypothesis has brought in a new reason for supposing 4, to depend on the direction of displacement, viz: on account of the stress of the medium. A general displacement of the medium midway between two nodal planes, when it is restrained at innumerable points by the ponderable particles, will produce special distortions due to these particles. The nature of these distortions is wholly determined by the direction of displacement, and is hard to conceive of any reason why the energy of these distortions should not vary with the direction of displacement, like the energy of the general distortion of the wave-motion, which is partly determined by the displacement and partly by the wave- normal.+ * See note on page 467. + The reader may perhaps ask, how the above reasoning is to be reconciled with the fact that the law of double refraction has been so often deduced from thé elastic theory. The troublesome terms are 6, and the variable part of A,, H. J. Biddle—Surface Geology of Southern Oregon. 475 But the difficulties of the elastic theory do not end with the law of double refraction, although they are there more con- spicuous on account of the definite and simple law by which they can be judged. It does not easily appear how the equa- tion of energies can be made to give anything like the proper law of the dispersion of colors. Since for given directions of the wave-normal and displacement, or in an isotropic body, Byp is constant; and also A, and 6,, except so far as the type of the vibration varies, the formula requires that the square of the index of refraction (which is inversely as V’) should be equal ' to a constant diminished by a term proportional to the square of the period, except so far as this law is modified by a varia- tion of the type of vibration. But experiment shows nothing like this law. Now, the variation in the type of vibration is sometimes very important,—it plays the leading role in the phenomena of selection absorption and abnormal dispersion,— but this is certainly not always the case. It seems hardly possible to suppose that the type of vibration is always so vari- able as entirely to mask the law which is indicated by the formula when A, and 6, (with B,,) are regarded as constant. This is especially evident when ‘we consider that the effect on the wave-velocity of a small variation in the type of vibration will be a small quantity of the second order.* The phenomena of dispersion, therefore, corroborate the con- clusion which seemed to follow inevitably from the law of double refraction alone. Art. XLIL—Wotes on the Surface Geology of Southern Oregon ; by HENRY J. BIDDLE. DurinG the Summer of 1887, the writer had occasion to visit that portion of southern Oregon which lies within the area of interior drainage, and forms the northwestern part of the Great Basin. In the intervals of other work, some notes on the surface geology of the region were made, which, though necessarily fragmentary and incomplete, may yet be of sufhi- which express the direct action of the ponderable molecules on the ether. So far as the (quite limited) reading and recollection of the present writer extend, those who have sought to derive the law of double refraction from the theory of elastic solids have generally either neglected this direct action—a neglect to which Professor Stokes calls attention more than once in his celebrated ‘‘ Report on Double Refraction” (Brit. Assoc., 1862, pp. 264, 268,)—or taking account of this action they have made shipwreck upon a law different from Fresnel’s and con- tradicted by experiment. * See volume xxiii of this Journal, pp. 271, 272, or Lord Rayleigh’s ‘‘ Theory of Sound,” vol. i, p. 84. Am. JouR. Sc1.—THiIrD SeRies.—VOL, XXXV, No. 210.—JUNs, 1888. 29 % 476 Hf. J. Biddle—Surface Geology of Southern Oregon. cient interest to justify their publication. This region was reconnoitered by Mr. I. C. Russell in 1881 and 1882; and to his description* reference must be had for a complete account of its topography and surface geology. These notes are merely intended to supplement some of the observations of that writer, and to call attention to a few points not previously noted. A portion of northern California, which has the same topograph- ical features and geological structure as southern Oregon, is included in the following observations. The first region to be considered is Warner Valley. This is a long, narrow valley, bounded on both sides by fault searps of grand proportions, and extending in a nearly north and south direction. Its southern end is close to the point where the dividing line between California and Nevada meets the southern boundary of Oregon. This valley, as already notéd by Russell,t was occupied by a Quaternary lake, which never overflowed ; and in its lowest portions are, at present, a chain of shallow lakes, and marshes. These lakes all drain, during the wet season, into the northernmost lake; and are conse- quently, with the exception of the latter, nearly or quite fresh. The northernmost lake, on the contrary, is alkaline and brack- ish. A sample of this body of water, collected in September, was found to contain about four grams of solid matter to the liter. Qualitative analysis showed the presence of sodium, magnesium, traces of calcium and potassium, chlorine, sul- phuric and carbonic acids,—the chief constituent being com- mon salt. The salts contained in this lake do not, however, represent the total amount left by the evaporation of the ancient lake. On the east side of the valley, near its northern end, is a group of ponds and marshes, the waters of which are highly concentrated salt solutions. When dried by the heat of summer they leave crusts of various salts. The common salt from these ponds, though somewhat impure from the admixture of sulphates, has become of importance to the country round about; and several hundred tons are collected annually for salting sheep and cattle. As the supply is renewed every year, it is reasonable to infer that the salt is derived from the sediments in the bed of the ancient lake, which absorbed most of the salts left upon its desiccation. In addition to sodium chloride, the waters of these ponds contain a great quantity of sodium and magnesium sulphates, and a trace of borax. In the mud beneath the ponds are crusts of sodium sulphate, and nodules, up to three inches in diameter, of a mineral which has the composition of Ulexite, a borate of soda and lime. * Fourth Annual Report of the U. S. Geological Survey. A Geological Recon- naissance in Southern Oregon, by I. C. Russell. + Loe. cit., p. 459. Hf. J. Biddle—Surface Geology of Southern Oregon. 477 Next to be considered is the region embraced in the valleys of Summer, Abert and Goose lakes. While each of these lakes has its own system of drainage, all being at present without outlet, yet from the fact that they are only separated by divides ‘of slight elevation in comparison to the surrounding mountains, they can conveniently be grouped together. Another reason for considering them together is, as will be shown, the proba- bility that they once belonged to the same drainage system. The valleys of Summer and Abert lakes, together with the low region between them, now occupied by the Chewaucan Marsh, were filled, during the Quaternary period, by a lake of considerable size. The boundaries of this ancient lake have been mapped by Russell.* In the lowest portions of its bed are the existing lakes, Summer and Abert. They resemble each other in many respects, and are both highly charged with various salts in solution; but the waters of Abert lake contain about twice as great a percentage of total solids as those of Suimmer lake. (Qualitatively the salts in both lakes are the same. A sample of the water of Abert lake was col- lected on the 18th of September, 1887, off a rocky point near the middle of the west shore. It was taken one foot below the surface and about ten yards from land; the depth of the water being five feet, and temperature 15° C. The following analysis of this sample by Dr. T. M. Chatard, of the U. 8. Geological Survey, is published by permission. Specific Gravity 1:03117 at 19°8°. In 25 c.c. TR EES grams, Grams in Percentage Average. a liter. of total solids. SiOE ee _.- 0°0063 0°0053 0:00580 0°232 0°59 Rees he Be OLOL33N) OFON36 - OLOls4s 0°538 Wees7/ Nae meses OS674 0:36.74 0;36725 14°690 aieak SOAP sea: 00148 0°0146 0:01470 0°588 1:50 OF 22220-00305) 00029 -50:00295 0-118 0°30 Ol ae eck OSIGH OSG Osa 13°462 34:37 CO, Ne ree ONS Olney. Ol rae) 7:024 17°93 O Wien) aS 0°0615 0:0616 0°06155 2°462 6°28 Figmpblcarbonatest saps ee oe 0:058 0°15 Grams.._. 39-172 100-00 Hypothetical Composition. Grams in a liter. Percentage of total solids. DIO) Rest See pee 023250. 0°59 IRC ae 1:027 2°62 INCE pain ae se 216380 54°58 INGE OF eee wes 1050 2°68 NaC Ori a2 2 10°611 27°09 INAH COS ee 4°872 12°44 39°172 100-00 * Loc. cit., map 83. / 478 H. J. Biddle—Surface Geology of Southern Oregon. An analysis, quoted by Russell,* of a previous sample from this lake showed a remarkably high percentage of potassium salts. The above analysis, on the contrary, shows a less pro- portion of potassium than reported in the waters of Mono Lake, Owen’s Lake, or Great Salt Lake.t The writer is at a loss to account for the wide variation between these analyses. Both show a very low percentage of sulphates, far less than in the other lakes of the Great Basin mentioned. The occurrence of tufa deposits in the bed of the ancient lake alluded to has not previously been reported. In the low region between the existing water bodies fragments of a calca- reous crust, usually less than one-half inch in thickness, to- gether with concretions of small size, lie sparsely scattered on the surface. Near the shore of Summer Lake the sands are cemented into a crust from one-eighth to one-half inch thick, which appears to be of very recent formation, and might have been formed when the lake stood but a few feet higher than at present. These facts merely go to show that the history of this ancient water body was, in a : small way, similar to that of the larger inclosed lakes of the Great Basin. Goose Lake Valley is south of the region just desenibede it extends nearly north and south, and hes partly in Oregon, partly in California. At its northern end it is connected by a low pass with the southern end of the depression in which Abert Lake lies. This valley was occupied by an ancient lake, the boundaries of which have never been mapped. It had about twice the area of the present Goose Lake, and a depth approaching 300 feet. As the hillsides in this region are in part clothed with forest, the ancient beach lines do not form as noticeable a feature as in the arid valleys north and east of it. Near the town of Lakeview, however, is a conspicuous and well defined terrace, showing the surface level of the ancient lake. - This terrace is deeply cut into the spurs of the mountain side, having in places a width of several hundred feet. It has two minor benches, at an elevation respectively of 250 and 280 feet above the floor of the valley.t These benches are in places level, but usually have a lakeward slope of about 5°, and are separated by a somewhat steeper slope. On the side toward the valley the slope increases abruptly, reaching 25°, while toward the mountain there is a gradual increase of slope until the normal inclination of the mountain side is attained. There is no cliff separating the terrace from the mountain slope. The surface of the two benches is often covered with * Loe. cit., p. 454. + For a compat soe of the analyses of these, and other inclosed lakes, see Monograph XI, U. 8. G.S Geological History of Lake Lahontan, by I. C. Russell, Table C. + These measurements are by aneroid. H. J. Biddle Surface Geology of Southern Oregon. 479 rounded and subangular pebbles, though in places these occur but sparingly. In the northernmost part of the ancient lake basin is a row of round topped hills, stretching five or six miles from the mountain border on the west and nearly span- ning the valley. These hills rise fully 200 feet above the level plain at their feet, and are covered from base to summit with water-worn gravel. While it is evident that these vast accu- mulations of gravel were formed by the waves and currents of the ancient lake, yet it is not clear to the writer how they ob- tained their present form. The supposition that an ancient, and once continuous, gravel bar or embankment has been cut to its base, at several points, by lines of recent drainage, par- tially explains the peculiar topography. Passing to the extreme northern end of the valley, the pass leading to Abert Lake is found to be lower than the ancient beach lines and gravel accumulations alluded to. At the divide in this pass, and thirty or forty feet above the lowest point, a considerable quantity of water-worn pebbles may be seen on the hillside. Taking these facts into consideration, it is im- possible to avoid the conclusion that when Goose Lake Valley was filled to its highest beach line its waters overflowed this pass, and communicated with the lake north of it. But the ancient shore lines cannot be traced from one valley to the other, owing chiefly to the broken nature of the country; and the evidence of this fact is not as clear as could be wished. When the pass alluded to was overflowed it must have formed a narrow strait, of no great depth, connecting two large bodies of water. Goose Lake found an outlet at its southern end, and hence this strait might have furnished an outlet to the ancient lake north of it, by which it could discharge its sur- plus water. This question will be referred to later on. Although Goose Lake does not at present overflow, yet a rise of but a few feet would cause its waters to discharge south- ward into the North Fork of Pit River, and thence into the Sacramento. This is reported by Russell* to have taken place as recently as 1869, and again for a short period in 1881. When the lake stood at the level of its highest beach line, it is evident that the valley of Pit River was yet to be cut; and the depth to which the waves eroded the mountain side shows that for a long time the lake maintained a nearly constant level, and nothing was accomplished toward deepening the channel of discharge. But when the cutting down of this channel com- menced it must have been comparatively quickly accomplished, as is shown by the absence of beach lines at lower levels than those mentioned. Perhaps other lakes, on the lower courses of Pit River, had first to be drained; and not until this had been * Reconnaissance in Southern Oregon, p. 456. 480 H. J. Biddle—Surface Geology of Southern Oregon. effected did the outflowing waters have sufficient fall to carry on the work of erosion. Of course the hypothesis is admissi- ble that the lake had at first no outlet, and was in course of time tapped by a stream belonging to another drainage system, cutting back its channel across the divide. Had the climatie conditions of a former period continued to the present day, the work of deepening the channel of outflow would most likely have gone so far as to completely drain the valley, and leave only marshes and meadows in place of the present water body. But before this task was accomplished the supply of water was so diminished that the lake disposed of it all by evaporation, and none escaped to continue the cutting down of the outlet. The question naturally occurs, did the great lake north of this also cut down its outlet? But as there is no evidence of erosion by running water in the pass mentioned, which was once a strait connecting the two water bodies, the question must be answered in the negative. Naturally nothing could be accomplished toward deepening this channel until the level of Goose Lake had been lowered to about the level of the bot- tom of the strait. As has been shown, a long period must have elapsed before this was the case; and if at the end of this period, the humid climate of Quaternary times was giving place to the later aridity, the lake would have no surplus waters to discharge. Indeed, we know that many of the lakes of this region never overflowed, even during the periods of greatest humidity; and with a large surface for evaporation and comparatively small tributary drainage area, the lake in question may never have had any surplus water to dispose of. The waters of Goose Lake do not appear ever to have deposited tufa. The existing lake is very nearly fresh, con- taining less than one thousandth of solids in solution, and is ‘inhabited by fish. Unfortunately there are no good exposures in the bed of the ancient lake, and the character of its sedi- ments is unknown. South of the region just described is a basin, drained by Pit River, known as Warm Spring Valley. Although the district has not been visited by the writer, yet from the topography it seems safe to assume that this valley has also contained an ancient lake which was drained by the cutting down of its out- let. When the surface geology of this region shall be system- atically studied, traces of many extinct lakes hitherto unnoticed will no doubt be found. : The next region to which these notes have reference is Sur- prise Valley, lying in the northeast corner of California. This valley contained a Quaternary lake which never overflowed. Its modern representatives are three shallow lakes occupying the deepest portions of the basin, and known respectively as HI, J. Biddie—Surface Geology of Southern Oregon. 481 Upper, Middle, and Lower, Alkali Lake. During the summer these lakes often dry up completely, leaving broad, level stretches of fine-grained yellow mud. When visited by the writer in September, 1887, the middle lake was quite dry, the others nearly so. The water in the upper or northernmost lake was found to be a strong saline and alkaline solution. It contained about 45 grams of solids to the liter, mostly sodium - chloride. By digging into the mud near the center of the middle lake the following section was obtained, beginning at the surface: 4 feet ot yellow fine-grained mud, 3 inches of fine white volcanic dust, 3 feet of black mud smelling of hydrogen sulphide. At the depth of seven feet the hole in the lake bed filled with brine, which was found to contain about 88 grams of salts to the liter—mostly’sodium chloride, with some car- bonate and sulphate. This shows what has become of the salts which must have accumulated during a long period in the basin of the ancient lake. But a fraction of the total amount exists in the shallow lakes of to-day; the greater portion must be looked for in the brine saturating the mud beneath them to an unknown depth. The existence of a stratum of volcanic dust in this valley is a fact of interest hitherto unreported. Similar strata occur among the sediments of the ancient Lake Lahontan, as re- ported by I. C. Russell.* That writer regards them as derived from the craters about Moro Lake, Cal., and has observed such material up to 200 miles from the supposed place of eruption. The middle of Surprise Valley is about 250 miles from Mono Lake, but less than half that distance from the volcanic region of Mt. Shasta and Lassen’s Peak. Further observations are necessary to determine from which direction the volcanic dust of Surprise Valley was derived. There seems to be in this oc- currence evidence of very recent volcanic activity. The time in which a narrow lake, receiving annual supplies of sediment- laden water and eeolian dust, has deposited four feet of mud in - its bed, can hardly be very great. The region next to be considered lies on the border of the Great Basin, and possesses the same topographical features as the valleys previously mentioned; but now belongs partly to the hydrographical area of the Pacific. This is the region em- braced in the valleys of Rhett Lake, and the Upper and Lower Klamath lakes. It lies partly in Oregon, partly in California. The whole may be regarded as one valley, formed by a comphi- cated system of faults, with a nearly level floor on which the lakes mentioned lie. Two of these lakes, the Upper and Lower Klamath, discharge their waters by way of the Klamath River into the Pacific, while Rhett Lake on the other hand * Lake Lahontan, p. 146. 482 H. J. Biddle—Surface Geology of Southern Oregon. has no outlet. But a slight rise in the water of the latter would cause it also to become tributar y to the Klamath River, as there is no high ground between. There seems to be no doubt that this system of valleys was occupied by a large lake, which has been nearly drained by the cutting down of its outlet. The writer was, however, unable to detect any beach lines which would show the extent and depth of the ancient lake. It is possible that it was so shallow that its waves had little force, and left no trace of their action. But fortunately the sediments in its bed are in piaces exposed. Lost River, an affluent of Rhett Lake, has cut its channel into the floor of the valley to the depth in places of 40 feet. A bluff on the south side of this stream, about 10 miles southeast of the town of Linkville, shows a good section of the lake beds. They are seen to consist chiefly of a light gray, fine-grained earth, which at first sight might be taken for chalk. Inter- stratified with this are occasional layers, but a few inches thick, of sand and pebbles with a ferruginous cement. When the earth forming the mass of these deposits is exam- ined under the microscope it is seen to consist wholly of infu- sorial remains. .It is homogeneous and of exceedingly fine texture; compact enough to ~ form steep bluffs, but in small lumps easily crushed between the fingers. It is so light as to float for a moment in water, and adheres slightly to the tongue. The strata dip about northeast, or toward the mountains, at an angle of 12°. This dip may be due to deposition in inclined layers; but in that case one would expect to find the slope in the opposite direction, or toward the middle of the valley. Without more extended observations it can not, however, be maintained that a tilting of these beds has taken place. At the top of the bluff they are seen to be overlaid by a horizontal layer of gravel, containing rounded lumps of the infusorial earth. A system of joints extends through the beds in a plane about parallel to the strike and at right angles to the dip. For a considerable distance the channel of Lost River lies in the infusorial beds, and wherever exposed the jointing is a notice- able feature. The same material may be traced for about 10 miles along the northeast edge of the basin in which Linkville hes; the total extent of the deposit is yet to be determined. Mr. J. 8. Diller, of the U. S. Geological Survey, has called attention® to similar infusorial deposits on Pit River and the lower courses of the Klamath. They occur, as in this case, in the beds of extinct lakes. The writer desires to express his obligation to Mr. Russell, of the U.S. Geological Survey, for his kind assistance and advice ; to Dr. Chatard, of the Survey, for his analysis quoted; and to Mr. Merrill, of the U. 8. National Museum, for the ae determination of voleanic dust. * U.S. G.S. Mineral Resources, 1886, p. 588. FW. Clarke--Some Nickél Ores from Oregon. 483 Art. XLII.—Some Nickel Ores from Oregon; by F. W. CLARKE. In or about the year 1881, extensive deposits of nickel sili- cates were discovered in Douglas County, Oregon, In appear- ance, the ores are identical with the so-called “ garnierite ” and “noumeaite” of New Caledonia, and many specimens bearing those names have found their way into collections of minerals. At present, the deposits at Riddle, Oregon, are being worked by the Oregon Nickel Company, and through, the kindness of Mr. Will Q. Brown, an admirable series of the ores was re- cently sent to the United States Geological Survey for investi- gation. According to Mr. Brown the deposits all lie at or near the surface, in beds from four to thirty feet thick. Min- ing is carried on through open cuts or quarries, and no second bed has ever been found under lying the first. The specimens at my disposal represent a wide range of appearances. They include samples of the country rock and of the associated chromite, and the nickel silicates themselves vary much in color and texture. The finest specimens are bright apple green, and quite compact, and from this they range through: duller shades into masses of distinctly earthy texture. Most of them are intermixed with oxides of iron and with quartz, and even the purest mineral, like the garnier- ite of New Caledonia, is seamed with thin sheets of chaleed- ony. All of the nickel beari ing samples are much decom- posed; and one particularly beautiful specimen is distinctly a conglomerate or breccia, having nodules of the green ore im- bedded in it side by Ride with pebbles and fragments of other material. Like all’ the nickel silicates which have been so far observed in nature, these ores are unmistakably products of alteration; and the problem of their genesis is somewhat inter- esting. For comparison with them Thad a suite of the New Caledonia minerals, received from Professor Liversidge, and a large series of the genthites from Webster, N. C., collected last summer by Mr. “W.S. Yeates. All three localities have much in common, and the three sets of specimens point clearly to one conclusion, which will be stated farther on after the evi- dence for it has been presented. In composition, the nickel silicates from any locality vary widely ; for the earthy nature of the material renders it im- possible to secure anything like a homogeneous substance for analysis. The purest specimen of the Riddle ore was dark apple green, compact, and amorphous; but so permeated with films of silica that a definite mineral could not be isolated. With the best material obtainable I secured the following re- 484. FW. Clarke—Some Nickel Ores from Oregon. sults; which I give side by side with two published analyses by Hood, * in order to show the variations. Clarke. Hood. Hood. WosstatalOns Cx se: Sly : nS Loss onignition.... 6°99 en030% fee ANI O) II (O). oe Seas 118 1°38 1°33 Siu anya aT PUA 48-21 40°55 Mic @ teem eel e056 19-90 21°70 INT Oe rr eo yr Tay 23°88 29°66 ‘ 99°90 100-00 100°24 Neither lime, sulphates, chromium, nor cobalt could be de- tected. Like the New Caledonia garnierite, the fragments of this silicate fell to pieces when immersed in water. Of the New Caledonia silicates many analyses have been published, notably by Liversidge and Leibius, Typke, Damour, Garnier and Ulrich, and they vary between widely separated extremes. Not only are there the variations due to mutual replacements of nickel and magnesia, with a range in the per- centage of NiO from 0-24 to 45°15 per cent, but there are also great differences in silica and in hydration. It is therefore impossible to say whether. we have to deal with one nickel salt, varying only in its impurities, or with several compounds: although the general similarity of the material from different localities renders the former supposition the more probable. According to Ulricht the noumeaite and garnierite consist of a soapstone-like base, with a hydroxide or silicate of nickel dis- tributed through it in veins and patches; while Des Cloizeauxt regards noumeaite as a magnesian hydrosilicate impregnated with nickel oxide.» The latter view, however, is hardly prob- able, especially when we consider the origin of the minerals; and Typke§ has cited evidence against it. The prevalent opin- jon, that we have to deal with one or more definite hydrosili- cates of nickel, is best sustained by careful comparative study of the specimens, even though the salts may not be obtained - pure or positively formulated. The reciprocal variation of nickel and magnesia in more than twenty published analyses, excludes from further consideration the idea that the nickel is present to any great extent as hydroxide. For temporary con venience we may use the well-recognized name ‘ genthite ” generically, and apply it to all the “nickel silicates from the above-named localities. Of the ‘‘ country rock” surrounding the Oregon beds one large, clean, fresh specimen was received. This was subjected * Mineral Resources of the United States for 1883. + This Journal, IIT, xi, 235. Bull. Soc. Min., i, 29. § Chem. News, xxxiy, 193. FW. Clarke—Some Nickel Ores from Oregon. 485 to analysis, and also, through the kindness of Mr. J. 8. Diller, to careful microscopic study. The olivine separated from it by Mr. Diller was analyzed as well. although the material was not absolutely free from enstatite and chromite, and both analyses are here presented together. — Rock. Olivine. Remitron) 2 a2 22) hep nA Aa oT) SiO ee eis Bs ad hate 41°43 42°81 PAA OP Sets Sc etiae ee "04 Ee Ori Ouorem Nine: Lahn "76 “79 Bien) Pea CA eng: 2°61 TREO) Se Ae SN re 6°25 7°20 Nj OS ee hk pate 10 26 MnO 2s ae ace none none Ca Oe ere Pee Wi en 55 none Jui Kear OSes Nese ay 43°74 45°12 99°80 99°36 It will at once be seen from these data that the rock con- tains nickel, and that the olivine separated from it contains even a larger proportion. This fact suggests a probable source - of derivation for the nickel in the altered beds of ore, and this view is maintained by the microscopic investigation. Con- cerning the latter, Mr. Diller reports as follows, discussing both the rock and the genthite. “The high specific gravity and dark yellowish green color of the country rock with which the genthite is associated at Riddle, Oregon, at once suggests that it belongs to the perido- tites, and such it is proved to be by investigation. It is a holo- crystalline granular rock, composed essentially of olivine and enstatite with a small percentage of accessory chromite and magnetite. The olivine predominates, so that the enstatite forms less than one-third of the mass. Both of these minerals are clear and colorless, but may be readily distinguished by their cleavage and optical properties. They are allotrio- morphic, i. e. not bounded by crystallographic planes, and do not contain prominent inclusions, excepting a few grains of chromite and magnetite and fine ferritic dust. Notwithstand- ing the comparatively fresh condition of the rock, to which, according to Wadsworth, the name Saxonite may be applied, it is completely permeated by a multitude of cracks filled with serpentine resulting from alteration. (Quartz also results from the metasomatic changes in the saxonite, and wherever the genthite occurs it is always associated with either quartz or serpentine.” “The genthite from Oregon varies in color from green to pale apple or yellowish green in reflected light,.and is compact 486 EF. W. Clarke—Some Nickel Ores from Oregon. with a faint suggestion of fine granular structure. Generally it is dull, but where most compact and traversed by a series of minute fissures or seams of quartz it has a decidedly waxy luster. Under the microscope it usually appears to be an ageregation of irregular grains which have in transmitted light a pale yellowish green to coffee-brown color, and a peculiarly clouded waxy aspect. Where the grains are very thin the genthite may be said to be transparent and isotropic, but the majority of them are only translucent. In the narrow seam of genthite lying between seams of quartz the former is indis- tinctly fibrous and feebly double-refracting; but its system of it crystallization could not be defi- nitely determined. In small veins it is free from grains of other minerals, but elsewhere it is very intimately commingled with quartz. The relation of the two minerals is shown in the accompanying figure 1, in which the shaded portions (3) are genthite, and the clear one (4) are quartz. The com- mingling of the two minerals is so intimate as to make it evident that both were deposited from solution in circulating waters. Veinlets of quartz are fre- quently found cutting across those of genthite, and in general it appears to be true that the latter mineral was laid down first, although it is probable that both were precipitated at about the same time. Although the purest genthite is to be found with quartz, the mineral is more commonly associated with serpen- tine; and this relation is a most important one in its genetic significance. The accompany- ing figure 2 represents the edge of one of the lar ger veins of gen- thite (3), with numerous vein- lets or fissures exténding out into the serpentine (2).. The tributaries are abundant on both sides of the vein. Figure 3 shows a vein of genthite (8) in the serpentine (2), which en- velopes small masses of residuary oxide of iron (1), left by the decomposing olivine. The area represented is only 0°64 of a millimeter in diameter and contains no olivine; but less than half a millimeter ,from the boundary of the vein much olivine still remains, although deeply coated with oxide of iron and serpentine. The branching streamlets from the vein F.W. Clarke—Some Nickel Ores from Oregon. 487 of genthite, together with the manner in which the arms grad- ually fade away into the serpentine at once suggests the source from which the genthite has been drawn. The genthite and serpentine are thoroughly intermingled, but the former 1s gen- erally present in such small quantities as to be overlooked un- less it is the object of special research. It occurs in the ser- pentine directly connected with the grains of olivine from which the serpentine has been derived, and there is every rea- son to believe that the genthite came from the same source.” In order to secure completer confirmation of the idea that the nickel of the greater silicate deposits is derived from the alteration of nickeliferous olivine, Mr. Diller at my request, also examined specimens from Webster, N. C., and from New Caledonia. Concerning the Webster genthite Mr. Diller re- ports that “it is almost identical with that from Oregon, ex- cepting that it is not so thoroughly intermingled with quartz. The relation of the genthite to the serpentine and the olivine at the Webster locality is exactly the same as at Riddle. The rock at Webster differs slightly from that at Riddle in containing a smaller proportion of enstatite, and belongs to the peridotites to which the name ‘dunyte’ has been ap- plied” He also finds the New Caledonia mineral to be iden- tical with genthite in its physical properties, and says— “Under the microscope it varies from pale yellowish green to light coffee-brown, and is either completely isotropic or exhibits only faint aggregate polarization. Like the genthite of Oregon it is deposited in layers and cavities thoroughly intermingled with quartz, and in the same thin section may be seen serpentine with traces of olivine and enstatite so disposed as to clearly indicate that the serpentine, noumeaite, and other secondary products have resulted from the alteration of perido- tite.” This observation confirms the earlier one of Des Cloi- zeaux (1. ¢.), who stated that the noumeaite was imbedded in a serpentine rock which appeared to be derived from olivine, and which contained crystals of the latter mineral plentitully dis- seminated through it. A similar suggestion is made by Mr. H. J. Biddle,* who regards the nickel of the Webster deposits as an original constituent of the olivine rock, and cites an ex- periment of Mr. G. B. Hanna, who found 0:15 per cent of nickel oxide in a chrysolite from Waynesville, N. C. * Mineral Resources of the U. S., 1886. 488 G. P. Merrill—Augite from Little Deer Isle, Me. So far, the case appears to be clearly and conclusively settled as to the origin of the nickel silicates under discussion. Nickel is almost always present in small quantities in olivines, and T. Sterry Hunt, in reporting genthite from Michipicoten Island* calls attention to the fact that the metal is rarely absent from the serpentines, steatites, diallages, and actinolites of the Quebee group. Nevertheless, one other possible source of nickel mast be noticed. Roth,t+ in speaking of the genthite from the chrome mines of Pennsylvania, attributes it to the alteration of nickeliferous chromite; and the almost universal association of the latter mineral with genthite, renders the view deserv- ing of attention. But it must be remembered that chromite alters with great difficulty, while olivine decomposes with ex- treme ease; and morever the genthite from Oregon contained no chromium, although that metal was diligently sought for. Furthermore, Mr. Diller examined some of the chromite from the Riddle mines, and found that although it was penetrated by crevices filled with secondary minerals containing genthite, the chromite itself showed no evidence of alteration. Concerning the other silicates of nickel, described under the names of pimelite, alipite, conarite, réttisite, refdanskite, etc., little need here be said. Some of them are probably similar in origin to the better known genthite, although the conarite and rottisite, which contain small amounts of sulphur and arsenic, probably came from nickeliferous sulphides. For the other minerals above named there is too little evidence upon record to warrant any serious attempt at discussion. Laboratory U. 8. Geological Survey, March, 1888. Art. XLIII.—Wote on the Secondary Enlargement of Augites in a Peridotite from Little Deer Isle, Maine; by GEORGE P. MERRILL. WHILE engaged in the study of sections of a peridotite from Little Deer Isle in Penobscot Bay on the Maine coast, the writer observed certain peculiarities of the augitic constit- uent which, if rightly interpreted, seem worthy of notice in the columns of this Journal. The rock consists essentially of olivine and augite, with accessory magnetite, chromite, apatite, and rarely a plagio- clase feldspar (?) It therefore belongs to the variety of peri- dotites which Professor Rosenbusch designates as picrdte. * Report Geol. Survey of Canada, 1863, p. 506. + Allgem. und Chem. Geologie, vol. i, p. 225, 1879. G. P. Merrili— Augite from Little Deer Isle, Me. 489 Olivine is the prevailing constituent and in nearly every case examined has gone over completely into serpentine. The augite, which is the only constituent to which particular atten- tion need here be called, is of the normal type, of a faint yellow or wine red color in the thin section, and gives maximum extinction angles on clinopinacoidal sections of 40°. The mineral occurs in the form of broad plates with deep, rounded embayments and in long armlike forms reaching out and enfolding the altered olivines, the peculiar habit of the mineral in acting as a binding constituent being here dis- played in its best development. On casual inspection by ordi- nary light the mineral presents no features other than of the ordinary type, the rounded forms of the altered olivine abut- ting closely against the fresh augite, while the line of separa- tion is perfectly sharp and distinct as I have attempted to show in figs. 1 and 2. Here the portions marked (a) and bounded by the heavy wavy line represent in each figure a single augite individual.* More careful inspection, however, shows that in nearly every instance the augite is surrounded more or less completely by a narrow and extremely irregular colorless border which projects in the form of sharp teeth or tongue- like prolongations for a considerable distance into the serpen- tine (olivine) granules. This is shown by the portions marked (6) in the figures and is very noticeable when the section is viewed between crossed nicols. This irregular border I am inclined to consider as a true secondary growth, formed since the consolidation of the rock and analogous to the hornblendiec, feldspathic and quartzose enlargements described by F. Becke,+ Irvingt and Van Hise.§ * In fig. 1 the rock has been fractured and re-cemented by serpentine. The portions in the upper left and lower right field forming originally one crystal. + Min. u. Petr. Mittheil., vol. v, 1883. 4 Bull. U. S. Geol. Survey, No. 8, 1884. § This Journal, May, 1887. - 490 G. P. Merrili—New Meteorite from California. I am led to these conclusions from a consideration of the following facts: (1.) It would seem very improbable that the augite first separated from the molten magma in such irregu- lar forms; (2.) The original outline of the augite is perfectly sharp and smooth, eminently characteristic of augitic outlines in this class of rocks ; (8.) The new portion is much the lighter in color being in fact so nearly colorless as at first to be wholly overlooked when examining the section by ordinary light; (4.) It projects in very irregular and jagged forms into the serpen- tinized olivine (¢ in the figures). Indeed its appearance is such as to suggest that not only was its formation subsequent to the consolidation of the rock, but that it is an aecompani- ment of the alteration, the sharp tooth-like edges projecting into the olivines along the curvilinear lines of fracture much like the ordinary beginnings of serpentinization. The new growth, it should be stated, possesses in all cases the same erystallographic orientation as the original, the entire mass ex- tinguishing simultaneously between crossed nicols when in the position indicated in the figures. The néw portion is there- fore not a secondary hornblende such as Mr. Van Hise has shown occurring as a secondary growth on the augites of cer- tain Wisconsin diabases. The figures given were drawn with the aid of a camera Iucida and show correctly the relative width of the borders and the primary augites in two rather pronounced cases. No attempt has been made to draw in the serpentine portions of the slide, the mineral being merely indicated by the dotted areas (c) in the figures. The black opaque spots, it is scarcely necessary to say, represent magnetite. The writer wishes here to acknowledge his indebtedness to Dr. G. H. Williams, under whose instruction this and other rocks soon to be described were studied during the winter of 1887-88 in the laboratories of the Johns Hopkins University. National Museum, Washington, Feb. 15, 1888. Art. XLIV.—On a New Meteorite from the San Emigdio Range, San Bernardino County, California; by GEORGE P. MERRILL. THE fragments of the meteorite briefly described below were given the writer in March, 1887, by Mr. Thomas Price, the well-known Assayer and Bullion Melter of San Francisco, California. The stone was stated by Mr. Price to have been found by a prospector in the San Emigdio Mts., and to have been sent him for assaying, it being mistaken for an ore of % G. P. Merrill—New Meteorite from California. 491 one of the precious metals. Unfortunately, before its true nature was discovered the entire sample received was put through a crusher and hence pieces larger than of a few grains weight are unobtainable. To the unaided eye the stone is of a dull reddish brown color and shows an irregular fracture, presenting on casual examination nothing indicative of its meteoric origin. A pol- ished surface however, at once reveals its true nature. The stone belongs to the chondritic variety of meteorites and in thin sections under the microscope is seen to be com- posed of olivine and enstatite chondri rarely more than one or two millimeters in diameter, imbedded in a base the structural features of which are greatly obscured by stains of iron oxide. It is apparently composed of the same substances as the chon- dri themselves, but in a fragmental and finely divided condition. The chondri are often of irregular and angular form and show every indication of being themselves fragments of some pre- existing meteorite rather than mere products of rapid erys- tallization. Nickeliferous iron constitutes 6°21 per cent by weight of the stone and occurs in the forms of lumps and irregularly outlined areas often partially surrounding the chon- dri and acting to some extent as a binding constituent. It is closely associated with pyrrhotite.. There is also present in very minute crystals a colorless, polysynthetically twinned mineral which is presumably a monoclinic pyroxene. The mi- nuteness of the crystals and their imperfect outlines renders a satisfactory determination impossible. An analysis of the stone by Mr. J. E. Whitfield of the U.S. Geological Survey yielded results as follows: Mietallicsportion reich sie i ere ae 6°21 per cent. Soloblemm dilutest@ le. yone a ie ae 51:26 BW CXC SS IY 0) CES a at ea i AD 42°23 The metallic portion yielded iron 88°25 per cent; nickel 11:27 per cent; cobalt 0-48 per cent. The portion soluble in HCl includes the olivine, iron oxides and pyrrhotite; the insoluble portion includes the enstatite and twinned pyroxene. The great ‘amount of oxidation which the metallic portion has undergone renders both chemical and microscopic examinations far from satisfactory. Nevertheless as the stone presents very interesting structural features it has been my intention to describe it in detail as soon as proper drawings could be pre- pared for illustration. In view of the fact that the paper has already been delayed several months it is deemed best to devote a little space to the subject here. I hope to give a more complete description in the near future. National Museum, Washington, Feb. 15, 1888. Am. JouR. Scl.—THIRD SERIES.— VOL. XXXV, No. 210.—JUNE, 1888. sy 30 ” ? 492 Scientific Intelligence. SCIENTIFIC INTELLIGENCE. I. CHEMISTRY AND PHYSICS. 1. On the Relative Size of Molecules.—An attempt has been made by JAGER to determine the relative diameters of some of the elementary molecules and of certain atomic groups, based upon Kohlrausch’s investigations on the electric conductivity of certain metallic hydrates and salts in aqueous solution. If in a cylinder of unit length and unit cross section of such a solution there are m molecules; theu, the electromotive force along the axis being unity, we may represent by V the velocity with which the kathion will be propelled in the one direction, and by U the velocity of the anion in the other. If ¢ represent the quantity of positive or negative electricity belonging to each molecule the coefficient of conductivity x will equal (u+-v)m, in which eU=u and ¢V=v; and the specific molecular conductivity A will be : : v : : : equal to w+v. But, according to Hittorf, ype which 7 is the number of molecules passing through unit space in unit time. Hence w=(1—7)A and v=ni. Since the molecules of the ions have a certain velocity, they must meet in unit time a certain number of molecules of a different kind moving in the opposite direction; and therefore they will require energy to overcome the resistance, proportional to their rate of passage. Assuming the molecules to be spheres, and assuming the solution so dilute that no interaction takes place between the molecules of the dissolved substance; then, if the number of molecules in unit volume is a, and if a molecule of radius 7 passes in a certain direction through an environment of molecules whose radius is ~, we have 7+ p=R, by resolving the forces in two directions. The result is the same if the radius of the moving molecule is R and the molecules of the environment are mathematical points. If for one given mole- P —=—. = ——__. jn which C is a constant of int - cule we have v R' @4p) ntegra- tion; while for another molecule v’= ; then, dividing the first formula by the second, we have =o from which Fon ra=(r"+ py4/, — —p. Substituting in this equation the values for the relative velocities determined by Kohlrausch, and using to find r' and p, the diameters of the molecules of water and chlorine as calculated by O. Meyer; i.e. for water 96 X10~® and for chlo- rine 441079 centimeters, the value of U for water being 49, Jager has obtained the formula for calculating the diameter of a : 960400 - g given molecule Hea) 7 —44, the values obtained being ex- Chemistry and Physics. 493 pressed in 10~® centimeters. The following are the results ob- tained. Meee 4 Br (GN) Cl «Ke (NIH) (NOs): (C103) 4K h(SOn)niAg: eS 2 on Ole a Oile Ob OG. 29s 7.99). OOo LR Irs Tie Nplate 4(NH,). $(CO;) Age Na F Ba Cu 48r 4Ca 4Mg (C.H;02) eh ON 22 loos Hostess Lab w 4s a tGO) Ge $Na. 380.) Li 4Zn 4Me 4Zn $Cu Ai 165 165* 170 175 OG | ORG) DED) BENE The values marked with a star were obtained from the electric conductivity of magnesium, copper, and zinc sulphates. It will be noted that not only do the linear dimensions of molecules vary very widely, but that the diameter of a double molecule is greater than twice that of a single molecule; a necessary result of uniting two equal spheres. Moreover, the values for allied elements are nearly the same; as in the group chlorine, iodine and bromine; or barium, strontium and calcium. Again if the number of mole- cules in unit volume is proportional to the molecular volume, then by multiplying this volume by the molecular weight, we should obtain values proportional to the densities of the elements con- cerned. Since this relatiou does not hold good, except for closely allied elements, it follows that the ultimate particles of different molecules are differently arranged.—Monatsheft, viii, 498-507; J. Chem. Soc., liv, Abstr. 217, March, 1888. So Gea Re 2. On the Chemical Decomposition produced by Pressure.—The researches of Spring have shown that many substances which exert no action upon each other at atmospheric pressure, may be made to combine more or less completely if subjected to a press- ure sufficient to cause a perceptible condensation. Since the sub- stances experimented with had a smaller volume after union than that of their constituents, it became an interesting question to ascertain whether, in the case of a substance whose volume is greater than that of its constituents, the temperature of conver- sion can be lowered by pressure. Sprinc and van’t Horr have examined this action by submitting finely pulverized copper- calcium acetate to a pressure of 6000 atmospheres at a tempera- ture of 16°. The powder, though reduced to a crystalline mass resembling marble, showed no sign of decomposition. It was then subjected to the action of a screw press at a temperature of 40°, The results were marked, three-quarters of the mass being lique- fied, and becoming solid again when the pressure was removed. The sides of the containing vessel were covered with a coating of copper and small leaves of copper could be picked out of the mass. The dark blue of the acetate had changed to green, inter- spersed with white points indicating the separation into copper acétate and calcium acetate. Since the thermic eftect of the com- pression was less than corresponds to a rise of 1°, the above result must have been due entirely to a change of volume. At 494 Scientific Intelligence. 50° the piston sank through the mass without resistance. On repeating the first experiment using a lever press, the piston sank 1:25™™ in an hour; a rate which would require 110 hours to decompose the entire mass. Under the same conditions, potas- sium sulphate gave no perceptible diminution of volume. Since the chemical change is a function of the time, the acetate being decomposed more rapidly the higher the temperature and _press- ure, it is evident that the molecules of a substance do not assume the arrangement which corresponds to the given volume the moment it is reached. Moreover, a substance can be compressed without altering its state if the pressure does not last too long.— Zeitschr. Physikal. Chem., i, 227-230; J. Chem. Soc., liv, Abstr. 341, April, 1888. G. F. B. 3. On the Vapor-density of Ferric Chloride. —GRUNEWALD and Vicror Mryer have made a series of careful determinations of the vapor-density of ferric chloride at various temperatures, with a view of fixing its molecular formula. The chloride was pre- pared by passing dry chlorine gas over fine iron wire, and after sublimation, appeared as hexagonal plates, of a cantharides-green color by reflected, and purplish red by transmitted light. For the vapor-density in sulphur-vapor, 448°, the apparatus of Victor Meyer was used, filled with nitrogen, the bulb of which was only 45™™ in diameter and 125™™ long, while the whole apparatus was 670™™ long. The boiling sulphur was contained in an iron tube 60™™ in diameter, and 620™™ long, heated in an air bath by six Bunsen burners. As a mean of four accordant experiments, the vapor-density at 448° was found to be 10°487. The chloride after the experiments was carefully tested and tound to contain no trace of ferrous chloride. It therefore appears that even at the temperature of boiling sulphur, the density of ferric chloride is lower than 11°2, the value required by the formula Fe,Cl.,. The determinations were then repeated in the vapor of boiling phosphorus pentasulphide, 518°, in that of stannous chloride 606°, and in Perrot’s furnace at about 750°, 1050° and 1300°. The mean vapor densities of ferric chloride at these temperatures were found to be 9°569 at 518°, 8°883 at 606°, 5°459 and 750°, 5°307 at 1077°, and 5°135 at 1320°. It was found however that a pro- gressive decomposition took place at these temperatures, about a tenth of the chloride being decomposed at 518°, an eighth at 606° and a third at 750° and above. The authors conclude that since at 448° the vapor density of ferric chloride is less than corres- ponds to the formula Fe,Cl,, and since experiments at lower tem- peratures are not feasible, it follows that no temperature exists at which ferric chloride has a density corresponding to Fe,Cl,; and consequently since the vapor-density is lower, it must corres- pond to the formula FeCl,. In order if possible to check the dis- sociation of ferric chloride into ferrous chloride and chlorine, the experiments were repeated in an atmosphere of chlorine; the vapor-densities obtained, however, were nearly the same as those obtained in nitrogen. These results agree with those obtained for Geology and Mineralogy. 495 aluminum chloride by Nilson and Pettersson, which led them to give to this substance the formula AICl,.— er. Berl. Chem. Ges., xxi, 687-701, March, 1888. G. F. B. 4, Application of interference fringes to Spectrum Analysis.— Hermann Expert, working in the same direction as Professor Michelson, shows that the method of interference can be used to measure wave-lengths and to detect slight changes in refrangi- bility of spectral lines. In the latter respect he believes that the method is far more delicate than the ordinary spectrometric methods. One can measure displacements of fringes amounting to ;1, of the breadth of the fringes, or ,4, of the distance of the components of the sodium line, or a change in the velocity of light of 2 of a kilometer.—Ann. der Physik und Chemie, pp. 39- 90, No. 5, 1888. cea 5. Penetration of light beneath the surface of water.—In con- tinuation of his work upon this subject, M. F. A. Foren finds that, for chloride of silver, the limits of absolute darkness range from 45 meters in July to 110 in March. The variations in these lim- its correspond closely with those for visibility. The water of Lake Geneva, in which these experiments were tried, is more limpid in winter than in summer.— Comptes Rendus, April 3, p. 1004. deans 6. Velocity of Sound.—MM. J. Vrotte and Tu. VAuTIER con- clude from their researches that the velocity of a sound wave diminishes with its intensity; and that the pitch of the sound has no influence on the velocity of the wave.— Comptes Rendus, April 3, p. 1003. a 7. Magnetism and diamagnetism of gases.—At a meeting of the Physical Society held in Berlin, March 16, Helmholtz de- scribed a method of measurement due to Professor Topler, of Dresden. An index drop of petroleum is placed in a glass tube bent. at a very obtuse angle; on one side of the index is the gas which is to be investigated, and on the other side is atmospheric air. When placed between the poles of a powerful electro-mag- net, the index is moved according as the gas is more or less strongly attracted than the air; the amount of displacement is measured by a microscope. The delicacy of the method is ex- tremely great. It was observed that oxygen is most magnetic, then come air and nitric oxide; nitrogen, hydrogen, carbonic oxide, carbonic acid gas and nitrous oxide, on the other hand, are diamagnetic. ‘The method can also be employed for the de- termination of the pressure of small columns of gases.— ature, April 12, 1888. a at Il. GroLoGy AND MINERALOGY. 1. Three Cruises of the United States Coast and Geodetic Survey Steamer Blake in the Gulf of Mexico, in the Caribbean Sea, and along the Atlantic Coast of the United States ; by ALEXANDER Aeassiz. In two volumes of 314 and 220 pages 8vo, with numerous maps, plates and figures in the text. Boston / 496 Scientific Intelligence. and New York, 1888. (Houghton, Mifflin & Co.) Bulletin of the Museum of Comparative Zoology at Harvard College, Cambridge, Mass.—These volumes by Prof. Alexander Agassiz contain the best general review of the deep-sea conditions and pelagic and deep-sea life which has been published; and, at the same time, they give a detailed physical and biolovical account of one of the most interesting regions for deep-sea study in the world, with illustrations of the best kind in profusion. The three cruises of the Blake occurred in the seasons of 1877— 78 from December to March, 1878-79 commencing in November, and in 1880 commencing late in June. The first expedition was under the command of Lieut. Commander ©. D. Sigsbee, U. 8. N., and the second and third under Commander J. R. Bartlett, U.S. N. The methods of sounding and dredging were gradually per- fected with the progress of the work; Mr. Agassiz remarking, in his introductory chapter, that the criticisms of the first equip- ment and the suggestions of the Commanders and of the Lieuten- ants and other officers of the ship, constantly modified the meth- ods of work and so changed the apparatus that “it would have been difficult to recognize the original dredging implements as first devised.” The character of the final equipment of the “Blake” is the subject of the tirst chapter, which, like the others, has its many detailed illustrations. The various lines of sounding and dredging covered, as shown on a large map, the region about the Windward and other West India Islands, the northern half of the Caribbean Sea, a portion of the Gulf of Mexico, and along the Atlantic Coast. Besides these explorations of the American side of the ocean, there is also the work, as the Historical Sketch states, of the Fish Com- mission under the direction of Prof. Baird, which began in 1871 with naval tugs, but was carried on in 1882 with the steamer “ Hish Hawk” and in 1883 and since with the ‘ Albatross,” and the still earlier dredging by Pourtalés, an assistant of the Coast Survey, in the years 1867, 1868. “To the memory of L. F. Pourtalés, a pioneer in deep-sea dredging,” Agassiz has dedicated his work. Further, the important deep-sea explorations of the Challenger in these waters took place in 1873. Among the topics treated in the volumes, there are the following: The Florida coral reefs, and connected with it, the subject of the origin of the reefs; the topography of the eastern submarine coast region of the North American Continent and the causes de- termining the existing features illustrated by several bathymetric maps; the relations of the American and West Indian fauna and flora, embracing the west-American or Pacific as well as east- American, and including the subject of changes in the course of the Gulf Stream, and the geological consequences ; the perma- nence of coutinents and oceanic basins, a doctrine fully sustained by the facts gathered ; the deep-sea or sea-bottom formations ; the deep-sea fauna, and in connection the deep-sea rocks and fauna of ancient or geological time; the pelagic fauna and flora, Geology and Mineralogy. 497 or that of the open sea not of great depths; the temperatures of the Caribbean Sea, Gulf of Mexico and western Atlantic, illus- trated by deep-sea sections of the ocean, and a colored map of the bottom temperature-areas of both the North and South Atlantic; the Gulf Stream ; submarine deposits; the physiology of the deep-sea life including the subject of the constitution of sea-water, the degree of darkness of the depths, and other topics; and finally, descriptions of the West Indian fauna and sketches of the characteristic deep-sea types through the various subdi- visions of the animal kingdom from Vertebrates to Sponges, which occupy the second volume and are illustrated by nearly 500 figures of species—the work in part of various zoologists whose labors are acknowledged in the Introductory Chapters. The deep-sea soundings made under the direction of the U.S. Coast and Geodetic Survey in the West Indian seas have brought to light some marvellous facts with regard to depths, which Mr. Agassiz has finely illustrated by maps as well as descriptions. The tacts were for the most part first announced in 1884 by Mr. Hilgard, the superintendent of the Coast Survey, citations from whose paper are introduced. portion, of the Triangulation by Jd. S.Eimer soir May by Pronk 9. Dodge. Nov '86. from the Maps of Capt. Wilkes and W. T. Brigham. Cay), Jileet abuve Mean Tide. rem = SSS Mie Sn Sey SG I! CA Cpl dt lt Fh LS. Punderson @Son, New F Am.J. Sci. VoL. XXK V. Sulphur Houks Senay Plain ve Keg TD) PAniakoloa ee Buh Jatt A ay aycawo House 4 Kamchoaylt 94 iio iro 4h TI\\\’ IWS il \\\ MWAWAILAN GOVERNMENT SURVEY: WD Alexander Surveyor General Y THE CRATER OF Me SRALAUEA, HAWAII. ee SSS tt Survryed in Sept.- Ost. 1688, boy Frank S$. Dodge Outlines of Balemawnnita and NewLake andl peetien af the Tringnlatten dy” 7 SEmevao Atay by Trask 5 Dedye HDG ,, De yy) D i Mor 108 Sut With additions from the Maps of Capt. Wilkes and i W. T. Brigham. C7 tty Zk “a clarotiene are referred ts FoleanoHouns Verandah floor, Which (© £040 fect abure Awan Trae wHaven, & LS Purdersen OS Am.Jour. Sci Am.Jour Sci Vol XXXV ( — SS $$$ — — — SS se r yeas J - 5 3 = = : : —_ = i} || | | {| || | i i | il | | | | i | | | | || : || J } it i} hal i |i | | i} | | i | if i | | | | lf | aaa | } 1 | { i || i} teal } i | | | | | i | | H | i} yh | SSS | || 1 il | || | | | | | | | | | | | i} | || || ian — i 1 il || 1 | Ht ey | {| | | || ||| | i i) | s | | OF THE MIDDLE ATLANTIC. SLOPE. By Wal M&Goo, Geologist. nti Scale ut 2,.2¢ ),000, = 35mi, ‘lin. . STEREOGRAM. J + 425,000 19900. ts (— —— PLATE Ill. CP Spe, TI 5 TAG turk. ed PRE ~CAMBRI } ——-— lez. (aaa ad rue oe Te | Yyp Lr | LL), Fly, Wig / »., — D, PAHOTO-LITH. 3 = = PLATE II1. GEOLOGIC MAP LEGEND OF PORTIONS OF Taster New York, Westenn VERMONT, ees ESESSA z = Swesne SEES Western Mass. Anp Norra WEsTeaN Conn. Quaternary HUDSON c 2 C. _ (Brow pte MIP, BREN TUN CH oz ys CALCIREROUS a CAMBRIAN (GEORGIA) PRE-CAMBRIAN See a Bie oF ideo eee ee aloe wut vat CLA -D.WAL renton, Chazy, Calciferous .. a haa Pétdara ------=--Gen cane s ; CAMBRIAN a o Georgis—-------------- Limmestoriairest stnitt == Qnuartsite ANA oa PRE-CAMBRIAN .-- -.-----------------------------== SEL ANS. 7 Mie SES A < {2 Ay “SQ. ul > 1 = J v 4 j - es 4 J, y t a i¢ F| Taciue wens co PAGTOsLIT RS 7 , # Mat ae S es 4 ahepyitfeady ‘4 ¥ wa! mall ade i vou A" fy Aaah NGAP Ae net ao eee ORS aos. Am, Jour. Sci., Vol. XXXV, 1888. Plate IV. Gee yyy sail PW. ENE: C'B,PHIA. Am. Jour. Sci., Vol. XXXV, 1888. Plate V. WOE Am. Jour. Sci., VoL. XXXV. ; PVATE VAI; \N Le Se “ ped ae re OSS TYPE MOSS ENG, CO,. N.Y UPPER MEMBER OF COLUMBIA FORMATION. WASHINGTON, D. C. M Am. Jour. Sci., VoL. XXXV. PLATE VII. SoS dacs LOWER MEMBER OF COLUMBIA FORMATION. WASHINGTON, D. C. CONTENTS. vill Number 210. : Page Art. XXX VI.—Note on Earthquake-Intensity in San Fran- CIS COWEN VU tS cep lel OD IN evr shay Paull ore i eye eases ra a er ee OT XXXVII.—Relation of the Laramie Group to earlier and leer ormneymioars & los7 (On vay NAVGeng mo) Rae he ee 432 XXXVIII.—The Gabbros and Diorites of the ‘ Cortlandt Series” on the Hudson River near Peekskill, N. Y.; by (C1 GeV On by UNIT CSG SR a a i A ADE Oy eh 438 XX X1X.—Three Formations of the Middle Atlantic Slope ; Los NAV ere Uk ol Gao healer ae Oa ane eS eure a UN cia IN 2 448 XL.—Comparison of the Elastic and the Electrical Theories of Light with respect to the Law of Double Refraction and the Dispersion of Colors; by J. W. Grpps -__- .--- 467 XLI.—Notes on the Surface Geology of Southern Oregon ; [yy oa el 900) Oy py etn UN Re celal aC oN 475 XLII.—Some Nickel Ores from Oregon; by F. W. Crarkr_ 483 XLIII.—Note on the Secondary Enlargement of Augites in a Peridotite from Little Deer Isle, Maine; by G. P. IY GDF eg 6G Geek ee Be eee a arene NE UI ue ele ae A 488 XLIV.—New Meteorite from the San Emigdio Range, San Bernardino County, California; by G. P. Merrity---. - 490 SCIENTIFIC INTELLIGENCE. Chemistry and Physics—Relative Size of Molecules, 492.—Chemical Decomposi- tion produced by Pressure, SPRING and VAN’T Horr, 493.—Vapor-density of Ferric Chloride, GRUNEWALD and VictoR MEYER, 494.—Application of inter- ference fringes to Spectrum Analysis, H. EBprT: Penetration of light beneath the surface of water, F. A. Foret: Velocity of Sound, J. VIoLLE and TH. VAUTIER: Magnetism and diamagnetism of gases, 495. Geology and Mineralogy—Three Cruises of the United States Coast and Geodetic Survey Steamer Blake in the Gulf of Mexico, in the Caribbean Sea, and along the Atlantic Coast of the United States, A. AGAsSsiIz, 495.—Descriptions of new Fossil Fishes, J. 8S. NEWBERRY, 498.—Natural History of New York, Palzon- tology, J. Hatt, 499.—Geology of Minnesota, Bulletin No. 2, 1887, M. KH. WapswortH: Building-Stone in the State of New York, J. C. Smock: Car- boniferous Trilobites: Les Dislocations de lVécorce terréstre: Essai de Défini- tion et de Nomenclature par HMM. DE MARGARIE et A. Heim, 500.—Index der Krystallformen der Mineralien, 501. Botany and Zoology—Flora of the Hawaiian Islands, W. HILLEBRAND, 501.— Recent Advances in Vegetable Histology, 503.—Forms of Animal Life, G. ROLLESTON, 504.—Die Japanische Seeigel von Dr. Ludwig Déderlein: Biblio- theca Zoologica, 505. Miscellaneous Scientific Intelligence—Constant of Aberration: Discovery of Small Planets: Michigan Mining School, 505. Obituary—GERHARD VOM Ratn, 506. INDEX TO VOLUME XXXV, 507. hey RAI Chas. D. Walcott, U. S. Geological Survey. No. 205. Von. XXXV. ~ JANUARY, 1888. a ES Established by BENJAMIN SILLIMAN in 1818. AMERICAN JOURNAL OF SCIENCE. _ EDITORS JAMES D. anp EDWARD S. DANA. Prorrssors ASA GRAY, JOSIAH P. COOKE, ann | JOHN TROWBRIDGE, or Camsringe, ASSOCIATE EDITORS Prorsssors H. A, NEWTON anp A. E. VERRILL, or New Haven, Prorgessor GEORGE F. BARKER, or PurtLaperputa. THIRD SERIES, VOL. XXXV.—[WHOLE NUMBER, CXXXV.] No. 205—JANUARY, 1888. WITH PLATE I. ¢ NEW HAVEN, CONN.: J. D. & E. 8S. DANA. 1888, TUTTLE, MOREHOUSE & TAYLOR, PRINTERS, 371 STATE STREET, (ELT Eee EES Published monthly. Six dollars per year (postage prepaid). $6.40 to foreign sub- scribers of countries in the Postal Union. Remittances should be made either by money orders, registered letters, or bank checks, LITTELLS The LIVING AGE. met with constant commendation and success. | A WEEKLY MAGAZINE, it gives fifty-two numbers of sixty-four } pages each, or more than Three and a Quarter Thousand double- column octavo pages of reading-matter yearly. It presents in an inexpen- | sive form, considering its great amount of matter, with freshness, owing 2} to its weekly issue, and with a completeness nowhere else attempted, | - 1888 THE LIVING AGE enters upon its forty-fifth year, having | The best Essays, Reviews, Criticisms, Serial and Short Stories, Sketches of Travel and | Discovery, Poetry, Scientific, Biographical, Historical, and Political Information, i) from the entire body of Foreign Periodical Literature, and from the pens of Foremost Living Writers. The ablest and most cultivated intellects, in every department of Literature, Science, Politics, and Art, find expression in the Periodical Literature of Europe, and especially of Great Britain. The Living Age, forming four large volumes a year, furnishes from the great and generally inaccessible mass of this literature, the only compilation that, while within the reach of all, is satisfactory in the COMPLETENKSS with which it embraces whatever is of immediate interest, or of solid, permanent value. It is therefore indispensable to every one who wishes to keep pace with the events or intellectual progress of the time, or to cultivate in himself or his family general intelligence and literary taste. OPiInNnizions. “ We have thought that it was impossible to improve upon this grand publication, yet it does seem to grow better each year. . We regard it as the most marvel- lous publication of the time. . Nowhere else can be found such a comprehensive and perfect view of the best literature and thought of our times. . 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PUBLISHED WEEKLY at $8.00 a year, free of postage. CLUB PRICES FOR THE BEST HOME AND FOREIGN LITERATURE. (* Possessed of LitTELu’s LivinG AGE, and of one or other of our vivacious American monthlies, a subscriber will find himself in command of the whole situation.” — Philadelphia Evening Bulletin.) a For $10.50, THe Living AGE and any one of the four-dollar monthly magazines (or Harper’s Weekly or Bazar) will be sent for a year, with postage prepaid on both; or, for — $9.50, Tar Livine AcE and the St. Nicholas or Scribner’s Magazine, postpaid. re: LITTELL & CO., 31 Bedford St., Boston. ADDRESS THE AMERICAN JOURNAL OF SCIENCE, [THIRD SERIES.] Art. 1—The Speed of Propagation of the Charleston Earth- quake; discussed by Professor Simon Newcomp, U.S. N., and Captain C. E. Dutron, U.S. A. THE investigation of the time data of the Charleston earth- quake having been completed and a final result being reached, it is deemed proper, with the consent of the Director of the Geological Survey, to publish a brief abstract of the discussion. The full discussion will appear in the final report upon the earthquake, which report is now well advanced toward com- pletion. Immediately after the earthquake all, practicable measures were taken to collect information, and special effort was directed to obtaining the largest amount of time data. Through the courtesy of the Associated Press, notices were published in nearly all the newspapers of the country requesting those who had made such observations to forward them to the Director of the Geological Survey. Many persons did so. ‘The Chief Signal Officer instructed the observers of that bureau who had noted the time of the shock to report it, and he forwarded all such reports to the survey. The Western Union Telegraph Co. instructed its operators to forward reports and similar in- structions were sent by the Lighthouse Board to light-keepers. Special effort was made to secure newspapers from as many localities as possible. Most of the leading papers of the Am. Jour. Sci.—THirp SERIES, Vou. XXXV, No. 205.—JAN., 1888. 1 2 Newcomb and Dutton—Speed of country have an agent or reporter at Washington and he usually keeps a file of the paper he serves. The library of Congress keeps files of two or more papers from every State. As many of these as practicable were thoroughly examined. Many local papers were requested to furnish copies of their issues of Sept. Ist, 2d and 38d, and most of them complied. Many marked copies of papers were sent to the survey from unexpected sources. Altogether more than four hundred time reports were gathered. As might be expected a portion of these were useless. In order that it may be apparent which were selected for considera- tion and which rejected, the following account is given. There were about thirty which stated that the shock occurred “ about 10 o’clock”’ or “a few minutes before 10.” As a single min- ute is a very important quantity here, all such reports were summarily rejected as too indefinite. The reports from light- houses in most cases proved unavailable. These structures being situated most frequently where access to standard time is difficult, their clocks are regulated by the sun and an almanac. The uncertainties of this method of time keeping were evidently too great to justify any attempt to utilize them. But a few lighthouses keep standard time and in all such cases their reports were admitted to consideration. There were a few (nine or ten) which gave times so widely aberrant, differing by a quarter to half an hour from the great mass of records, that they were rejected. The whole number which received preliminary consideration was 316, many of which it was expected would also be rejected after a more thorough examination, due cause being assigned. These 316 observa- tions were catalogued in alphabetical order, the latitudes and longitudes of the localities being roughly ascertained and also their distance from the centrum. By far the most important time determination is that of the centrum, which was computed to be about six seconds earlier than that of Charleston. The time at Charleston is derived as follows. Among the numberless clocks stopped in that city by the earthquake, there were four which had compensated seconds pendulums and second hands and were of the pattern generally classed as “ jewelers’ regulators.” AJ] were compared daily with the time signal of the Western Union Telegraph Co., and the testimony is positive that none of them had errors on August 31st exceeding nine seconds, while the mean probable error of the four was certainly much less than this. The first was the regulator of James Allan & Co., Jewelers, No. 285 King street. It was regulated by means of a “sounder,” which was daily put into circuit with the Western Union time signal wire. The clock was corrected only when its error exceeded ie @ hee SiO ae Rs, No, 6 Murray Street, New York, Manufacturers of Balances and Weights of Precision for Chem- ists, Assayers, Jewelers, Druggists, and in general for every use where accuracy is required. April, 1871.—[tf.] PUBLICATIONS OF THE FOES HOPRKINS UNIVERSITY. I. American Journal of Mathematics. S. Newcoms, HKditor, and T. Crate, Associate Hditor. Quarterly. 4to. Volume X in progress. $5 per volume. II. American Chemical Journal.—I. Remsen, Editor. Bi-monthly. 8vo. Volume IX in progress. $3 per volume. Tif. American Journal of Philology.—B. L. GILDERSLEEVE, Editor. Quar- terly. S8yo. Volume 1X in progress. $3 per volume. IV. Studies from the Biological Laboratory.—Including the Chesapeake Zoological Laboratory. H. N. Marin, Editor, and W. K. BrooKs, Asso- ciate Editor. 8vo. Volume IV in progress. $5 per volume. V. Studies in Historical and Political Science.—H. B. ApbaAms, Editor. Monthly. 8vo. Volume VI ready. $3 per volume. VI. Johns Hopkins University Circulars.—Containing reports of scientific and literary work in progress in Baltimore. 4to. Vol. VII in progress. $1 per year. Vil. Annual Report.—Presented to the President by the Board of Trustees, reviewing the operations of the University during the past academic year. Vii. Annual Register.—Giving the list of officers and students, and stating the regulations, etc., of the University. Published at the close of the Aca- demic year. Communications in respect to exchanges and remittances may be sent to the Johns Hopkins University (Publication Agency), Baltimore, Maryland. NEW CATALOGUES JUST PUBLISHED. Sent post free on Application. BIBLIOTHECA PALAEONTOLOGICA CONTAINING ABOUT 2000 WORKS AND PAMPHLETS. BIBLIOTHECA BOTANICA MICROSCOPICA: Diatomeze, Desmidiez, Characee. CONTAINING OVER 300 WORKS AND PAMPHLETS. PBLEX Ts DAMES Natural History and Scientific Bookseller. 2 4% Taubenstrasse, Berlin, W. CONAN ARS: . XXXVI.—Note on Earthquake-Intensity in San Fra cisco; by E..S.“HoLpEN 4: (2S 5 XXXVII.—Relation of the Laramie Group to earlier anc later Formations; by C. A. Wuirm _2- 2 _._- =e XXX VIII.—The Cabbros and Diorites of the “Cortlandt — Series” on the Hudson River near Peekskill, N. Y.; by. GE. WILLIAMS 22 3212 2 x ee ee oe XXX1X.—Three Formations of the Middle Atlantic Slope ; Bere | by Wad. McGEr 2 2.2 er _ 448 — XL.—Comparison of the Elastic and the Electrical Theories of Light with respect to the Law of Double Refraction — -and the Dispersion of Colors; by J. W. Grpps ___-__ 2 467. | XLI.—Notes on the Surface Geology of Southern Oregon ; ee by Ho J. Bippun: = 322 eo ATS XLII.—Some Nickel Ores from Oregon; by F. W. OLaRKE. 483 XLIITT.—Note on the Secondary Enlargement of Augites in a Peridotite from Little Deer Isle, Maine; by G. P. MERRILL 22258 eo er .. 488 | XLIV.—New Meteorite from the San Emigdio Range, San — . Bernardino County, California; by G. P.) Murnmt. 2-2. 490 SCIENTIFIC INTELLIGENCE. Chemistry and Physics—Relative Size of Molecules, 492.—Uhemical Decomposi- tion produced by Pressure, SPRING and VAN’? Horr, 493.—Vapor-density of Ferric Chloride, GRUNEWALD and Victor Mnyrr, 494.—Application of inter- | ference fringes to Spectrum Analysis, H. Epert: Penetration of light beneath the surface of water, F. A. Forrn: Velocity of Sound, J. Vionne and Tx. | VAUTIER: Magnetism and diamagnetism of gases, 495. Geology and Mineralogy—Three Cruises of the United States Coast and Geodetic Survey Steamer Blake in the Gulf of Mexico, in the Caribbean Sea, and alone the Atlantic Coast of the United States, A. AGassiz, 495.—Descriptions of new Fossil Fishes, J. 8S. Newserry, 498.—Natural History of New York, Paleeon- tology, J. Hatt, 499.—Geology of Minnesota, Bulletin No. 2, 1887, M. E. WabswortH: Building-Stone in the State of New York, J. C. Smock: Car- | boniferous Trilobites: Les Dislocations de l’écorce terrestre: Essai de Defini- tion et de Nomenclature par EMM. DE MARGARIE et A.. HEIM, 500. Pee der. Krystallformen der Mineralien, 501. : Botany and Zoolog y—Flora of the Hawaiian Islands, W. Hines 01. —_ Recent Advances in Vegetable Histology, 503.—Forms of Animal Life, G. ROLLESTON, 504.—Die Japanische Seeigel von Dr, Ludwig Déderlein : Biblio- theca Zoologica, 505. Sears Miscellaneous Scientific Intelligence—Constant of Aberration: Discovery of Planets: Michigan Mining School, 505. | Obituary—GERHARD VOM RATH, 506. INDEX TO VOLUME XXXV, 507. i Ri f ’ 1 f % iv: eid A? t. 1 en PL ae ae | celal cbt he TT afield badly yey) vers ELE y a ee PeR Om Sar th qT nae VR Pegirout tHE OM oe Mary Te if nn aandnpeA anplagprer er” aed bras FOTET Peal ei eh YPN Dine ant ) pail ‘gat sa¥erstng | | Yu a) « iy ’ ra @aRonldons ~7 a28 *t | ahha i" 7 pp 44 al 7 le, Hope: bast Mo seaue Het sBieeaagpess aonell seneesgi haem 4, iY \) aha aq” a OS ee Ce “TT Ab (mee pe een aay Lido’ 14 reg si ak i NL - "eigy Pett TTGs, go ape STU ip Te HH TTL sent Aa TT a. 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