Laos re a & ?. 4 iZ ute Ys J) ee Pe < ~ f om ‘ 4>* oe | - a » ce LAay 8 mYero! aN | a 9 a> : ea § & © os 7 al “die Tas) Tan o ra , ee Ge Oh pf A Ve re sok ’ Tl fee = ae fe iy ere a as lot ck Lhe EPA s ey if er Or) at Bs te Bartha: feles- ~ oa - ’ : pe ae eae Sa ie ‘Vor. 63. CMawou 1824. — ' No. S11. SAMA WA MA MEA AMEA MAMA MASE AME) \ : - Published the Last Day of every Month.—Price 2s. 6d. Za ms ae of = THE Ss — a f PHILOSOPHICAL MAGAZINE 2 : 7 : el AND JOURNAL: fas by — Fy} _ COMPREIIENDING Si THE VARIOUS BRANCHES OF SCIENCE, | THE LIBERAL AND FINE ARTS, ___ AGRICULTURE, MANUFACTURES, | AND COMMERCE. ORY at AY at. “NUMBER @GGXI =. (0° 80) os For MARCH 1824. 3 . WITH TWO PLATES, : aDiasteative of Dr. Watcuner’s Examination of a new Mineral _ named Hyalosiderite ; and of Mr. Barry’s and M. PRAUEN- Me - HOFER’s Accounts of the Circular sprain ice one ait aie eZ By ALEXANDER TILLOCH, LL, D. ~€ * . MRA. FSA. EDIN. AND PERTH 5 CORRESPONDING MEMBER or THE ROYAL | Ce aa ACADEMY OF SCIENCES, “MUNICH; AND OF THE ACADEMY OF SCIENCES, ~ iS) LITERATURE AND ARTS, LEGHORN, ETC. SS | AnD RICHARD: TAYLOR, F.L.S. Ga MesteER or THE ASTRONOMICAL SOCIETY OF LONDON, AND OF THE eee SOCIETY, aay OF GREAT BRITAIN AND IRELAND, ait \ a ee, : 4EERD hie Bee Os ON DON: PRINTED BY. RICHARD TAYLOR, SHOE-LANE : JERENENED we Sold by Cadell ; _ Longman, Horst, Rees, Orme, Brown and Geen; ‘Baldwin, Yew Cradock, and ‘Joy; Highley ; Sherwood, Jones, and Co, ; ‘Harding; Under- BS) wood; ‘Simpkin and Marshall; London :—and by Constable ae Co. ie CF burgh ; ;and -enman, Glasgow. EXE SESE IE SESESENESESEN V a 7 vat TO CORRESPONDENTS. si st Mr. J. E. Gnay’s Zoological Notices, and Mr. Srurceon’s Experiments om a Thermo-magnetism, &c. are under consideration. We have been favoured with some interesting communications from Professor . . : : . . : : (2 ie Hare, of the University of Pennsylvania, which will appear in our next. ees SSS This day is published, in 8vo, with a Plate and a new Map constructed — from: the best authorities, price 12s. boards, WE “ELECTIONS from the WORKS of the BARON DE HUMBOLDT, relating to the Climate, Inhabjtants, Productions, and Mines of. MEXICO, with Notes and an Introduction. : By JOHN TAYLOR, Eszq,, Treasurer to the Geological Society, &c. » Printed for Longman, Hurst, Rees, Orme, Brown, and Green. - This work is intended to communicate information on these interesting: subjects, and particularly to those who may be investing Capital in the Mines of New Spain, or to others who may conteaiplate a residence in the country. Some recent and original communications will be found in the work, 6 THE SECOND EDITION OF THE CAMBIST, Essentially improved by the aid of Government. Published in two vols. 4to, price 41. 4s. in boards, HE UNIVERSAL CAMBIST, and COMMERCIAL INSTRUC. TOR ; being a full and accurate Treatise on the Exchanges, Moneys, Weights and Measures of all trading Nations and their Colonies, : By P. KELLY, EL.D. , _ Master of the Finsbury-square Academy, London; and Mathematical. ; _ Examiner to the Trinity-House. The Second Edition, corrected and enlarged. This edition comprehends the results of the late comparison of foreign weights and measures with those of England, effected for the first time on a general and systematic plan, by order and aid of the British Government,- ‘A Supplement on Indian Weights and Measures is in preparation by order of the Honourable Court of Directors. Nee aie These volumes also contain an entire revision of foreign exchanges from recent operations, and of foreign coins, from verified assays. An explica- tion of the coins is added, with a translation of their legends; and the work concludes with a copious index and commercial dictionary, = — ( Printed for the Author: and sold by Lackington and Co., Finsbury. square; by J. M. Richardson, 23 Cornhill ; and by the principal Book- — ‘ sellers of the United Kingdom, Of whom may be had, by the same Author, An INTRODUCTION to SPHERICS and NAUTICAL ASTRO. — NOMY, the 5th Edition. Also, ay The ELEMENT S of BOOK-KEEPING, the 7th Edition. i) ee et ay ees N88. | AM} We MGA EA ME) NGANEANGA ANG; ss Published the Last Day of every Month. cree ice 2s, 6d. i om Beg HE: FS PHILOSOPHICAL MAGAZINE 2 b= =——s AND JOURNAL: = ete ‘ : COMPREHENDING %| THE VARIOUS BRANCHES OF SCIENCE, _. THE LIBERAL AND FINE ARTS, AGRICULTURE, MANUFACTURES, AND COMMERCE. di NUMBER CCCXIII. For MAY © 1824. ~ WITH A PLATE Containing two new Species of Ascidia; and pe ey means, a new Batrachian Animal, WAN We) A SG Pe . By ALEXANDER TILLOCH, LL.D. ~ MLR IA. FSA. EDIN. AND PERTH; CORRESPONDING MEMBER OF THE ROYAL repair OF SCIENCES, MUNICH; AND OF THE ACADEMY OF SCIENCES, ¥ LAX Gir _ LITERATURE AND ARTS, LEGHORN, ETC. _-- Awp RICHARD TAYLOR, F.LS. < . ‘MEMBER oF THE ASTRONOMICAL SOCIETY OF LONDON, AND OF THE ASIATIC SOCIETY OF GREAT BRITAIN AND IRELAND. : tal AN W - FF zo) va oa ALERE Fuca MAM. . — WAM = \ LONDON: PRINTED BY RICHARD TAYLOR, cig tee cael WEAN ig 4 7 ‘Sold by Cadell ; Longman, Hurst, Rees, Orme, Brown and Green ; Baldwin, -Cradock, and ‘Joy; ; Highley; Sherwood, Jones, and Co. ; Harding; ; Under- 6 re) paprood 5 Simpkin and Marshall ; London :—and by: Constable and Co, Edin- {f = pe) burgh ; and Penman, Glasgow. AN Yale CVA Vay a Var ¥aity ae co cae " aie TO CORRESPONDENTS, 2 Re aa Want of room has compelled us to defer till next month some communications: ee "which we had hoped to be able to give in the present number. a a Our Correspondent XX will hear from us within a few days. Mr. Wiseman’s Paper on Dr. Young’s Report on Improvements in Gauging has ™ “ come to hand, and shall receive attention. In the Number for February last, in Mr. Sturgeon’s paper, page 97, fia 7, Se s the ‘Platinum i is positive to the sily er,’ read ‘the silver is positive to Be plati- num.’ : In the Number for April, page 268, line 5, for “ 400°, ” read “ 100°.” 22 GAGs ‘ PHARMACOPGIA LONDINENSIS, f - ue Iterum recognita et retractata, 1824, p. 6. . '« ACIDUM ACETICUM FORTIUS, mi vel «< Acidum Aceticum é teas destillatum.” URE CONCENTRATED ACETIC ACID, agreeable to the Baibple furnished at the request of the Committee of the Royal College of Physicians, may be had of the Manufacturers, BEAUFOY & co. South Lambeth, London. HE SECOND NUMBER of the ZOOLOGICAL JOURNAL will be Published on the 15th J une Eny W. PHILLIPS, Care Yard, Lombard Street. “ Vol. LIII. A Plate illustrative of Dr. Ure’s Experiments on Silage Mr. Lucxcocx’s Paper on the Atomic Philosophy, and Mr. Bo.ton’s on the Purification of Coal Gas.—A Plate representing Mi. Rennie’s © Apparatus empleyed in his: Experiments on the Strength of Materials; and the Marquis Rivotrui’3 Improvement on the Gas Blow-pipe.—A Plate illustrative of Mr. Merxur’s Paper on Calorific Radiation; Mr, Lowe’s on the Purification of Coal Gas; and Mr. Hucues’s on ascer- - taining Distances. —- A Plate illustrative of Dr. OLinrHus Grecory’s Paper on the different Rates of Pennincton’s Astronomical Clock at the - Island of Balta, and at Woolwich Common. Vol. LIV. A Plate illustrative of the Menar Baines. —A Plate illus- trative of Mr. Lowe’s Description of a Mercurial Pendulum.—A Plate illustrative of Mr. Hare’s Calorimotor, a new Galvanic Instrument.—A Plate illustrative of Captain Sasrnez’s Paper on Irregularities observed in the Direction of the Compass Needles of the Isabella and Alexander in the late Voyage of Discovery ; and Mr. Scoressy’s Anomaly in the Va. ” riation of the Magnetie Neédle as observed on Ship-board. Vol. LV. A Plate exhibiting Sketch of the Comet’s Path of July 1819. M, 4 —A Plate illustrative of the Annular Eclipseof the Sun on the 7th of © September next.—A Plate illustrative of Mr. Lane’s Instrument for gathering Fruit; Mr. Younc’s Mode of preparing Opium from the Papaver somniferum; and of Captain Forman’s Essay on a Property in Light which hitherto has been unobserved by Philosophers, —A Plate de- a scriptive of Mr. Curnsert’s improved Hydrg-pneumatic Apparatus, &e. —A Plate illustrative of Capt. Forman’s Essay on the Reflection, Refrac- — j tion, and Inflection of Light, &c.; and Mr. Cuarues Bonnycastie’s © _Communication respecting’ the Influence aa Masses of Iron on. the | Marie @ “ser’s Compass. ENGRAVINGS. 6 eae ee Wor. 63. Sun 1824. No. 314. SAMA MEA MEA MEA MEA MG) MEA MEA MEA MEA MENS sl _ Published the Last Day of every Month.—Price 2s. 6d. eo ey ] W 4 THE puirosoPHicaL MAGAZINE AND JOURNAL: . : COMPREHENDING THE VARIOUS BRANCHES OF SCIENCE, THE LIBERAL AND FINE ARTS, - AGRICULTURE, MANUFACTURES, | AND COMMERCE. | YAY ait v4 a ait Ve 4 NUMBER CCCXIV. For. JUNE. 1824. HCV ACY ACV ACY ANN fj By ALEXANDER TILLOCH, LL.D. Si MLR.IA-. F.S-A. EDIN. AND PERTH; .CORRESPONDING MEMBER OF THE ROYAL . -z : : ACADEMY OF SCIENCES, MUNICH; AND OF THE ACADEMY OF SCIENCES, te ; LITERATURE AND ARTS, LEGHORN, ETC. SS AnD RICHARD TAYLOR, F.LS. a Sean OF THE ASTRONOMICAL SOCIETY OF LONDON, AND ‘OF THE BSAA ee - or GREAT BEITAIN | AND IRELAND. R a -ALERE J\FLAMSIAM, hp : . 23E V a at W/ ie ‘4 a Y/ a LONDON: at PRINTED BY RICHARD TAYLOR, SHOE-LANE! Al sold’ by Cadell; Longman, Hurst, Rees, Orme, Brown and Green; Baldwin, _ Cradock, and d Joy; H ighley ; Sherwood, Jones, and Co.; Harding; Under- B ? wood ; Simpkin and Marshall; London :—and by Constable and Co. ie burgh ; and Penman, Gime’ &\ Y Aik TO CORRESPONDENTS. - hg The following communications have been received : ’ £94 % Mr. J. Urtrye on an Analogy between the Projectile and Gravitating Forces in the Planetary-System. : \ ee Mr. Squire on the great Difference in the Quantity of Rain about the 15th of May at Boston, London, and Gosport; with his Meteorological Summary for 1823, And = . Mr. T. Extey on the Theory of Parallel Lines. AN ORIGINAL WORK. On the 16th of July will be published, in Quarto, Weekly Numbers, price 6d. Monthly Parts 2s. each; got up in the first — style of workmanship, and with correct and highly finished Copper-. plate Engravings, NP HaNEh HE. MECHANIC’S ORACLE; or, ARTISAN’S COMPLETE LABORATORY AND WORKSHOP. Explaining, in an easy — and familiar manner, the General and Particular Application of PRAC- TICAL KNOWLEDGE to the different Departments of SCLENCE and ART. Illustrated by appropriate Engravings, executed by the first Ar-- | ~ tists, Sere _ —“ So work the honey-bees, Creatures that, by a rule in nature, teach The art of order to a peopled kingdom.” Edited by eminent Scientific Gentlemen of great mechanical talents, © who would rather the Public should judge of the work by its own merits, than be influenced by the sanction of their names. | hg Communications, Drawings, &e. &c. are solicited ; to be addressed to a 4 the Editors of the Mechanic’s Oracle, 38, Newgate Street, London. Sold — by all Booksellers and Publighers. - PHARMACOP(IA LONDINENSIS, Iterum recognita et retractata, 1824, p, 6. -« ACIDUM ACETICUM FORTIUS,” : . vel ; *« Acidum Aceticum é Ligno destillatum.” Bear CONCENTRATED ACETIC ACID, agreeable to the Sample ; furnished at the request of the Committee of the Royal College of | Physicians, may be had of the Manufacturers, BEAUFOY & CO. South Lambeth, London... _ This day is published, No. II., price 10s. of : dR mite tactics JOURNAL, to be continued Quarterly; con- ucte pee tla bs By THOMAS BELL, Esq., F.L.S, JOHN GEORGE CHILDREN, Esq. F.R. and L.S, JAMES DE CARLE SQWERBY, Esq., F.L S. and G. B. SOWERBY, F.L.S. iach eere ae Printed and published by W. Phillips, George Yard, Lombard Stréet, Sold also by G. B. Sowerby, 156, Regent Street; where communications — are to beaddressed ; W. and C, Tait, Edinburgh: and A. A. Royer, au Jardin des Plantes, a Paris. Fe Er AS ee s zx _ THE PHILOSOPHICAL MAGAZINE AND JOURNAL: COMPREHENDING THE VARIOUS BRANCHES OF SCIENCE, THE LIBERAL AND FINE ARTS, AGRICULTURE,- MANUFACTURES, AND COMMERCE. Bry ALEXANDER TILLOCH, LL.D. M.R.I.A. M.G.S. M.A.S. F.S.A. EDIN. AND PERTH ; CORRESPONDING MEMBER OF- THE ROYAL ACADEMY OF SCIENCES, MUNICH; AND OF THE ACADEMY OF SCIENCES, LITERATURE AND ARTS, LEGHORN, ETC. And RICHARD TAYLOR, FLS. MEMBER OF THE ASTRONOMICAL SOCIETY OF LONDON; AND OF THE ROYAL ASIATIC SOCIETY OF GREAT BRITAIN AND IRELAND. ““ Nec aranearum sane textus ideo melior quia ex se fila gignunt, nec noster vilior quia ex alienis libamus ut apes.” Just. Lirs. Monit. Polit. lib. i. cap. 1. VOL. LXIII. For JANUARY, FEBRUARY, MARCH, APRIL, MAY, and JUNE, 1824. LONDON: Nit See Men he Ne PRINTED BY RICHARD TAYLOR, SHOE-LANE: AND SOLD BY CADELL; LONGMAN, HURST, REES, ORME, BROWN, AND GREEN ; BALDWIN, CRADOCK, AND JOY; HIGHLEY; SHERWOOD, JONES, AND CO.; HARDING ; UNDERWOOD; SIMPKIN AND MARSHALL, LONDON :—-AND BY CONSTABLE AND CO. EDINBURGH : AND PENMAN, GLASGOW. AMIDLANM f = S eK — a= =2 CONTENTS OF THE SIXTY-THIRD VOLUME. ON two new Species of Narcissus . . . . . ~ Page 7 On the irregular Indications of Thermometers. By J. HERA- PATH, Esq. . 8 On the apparent " Magnetism “08; Metallic Titanium. By Witiiam Hype Wo tast on, DED. VP FES. oS C15 Chemical Examination of a Fragment of a Meteor which fell in Maine, August 1823. By Joun W. ees M,D.M.G.S. Lond. &c. . 3's « GRello A new Theory of Telescopes founded on rational Principles and interesting Experiments. By J. Reavr, M.D. . . 20 Description of certain Gangues of Spinelle brought from the Island of Ceylon by M. LescHENAULT De Larour.. By M. le Comte de Bournon, Chev. de St, Louis, F.R.S.§c. . 30 Description of an improved Gauge for ascertaining with Pre- cision the Pressure of highly compressed Steam, Gases, and Fluid Bodies. By Mr. SAMUEL SEAWARD . . .. 36 Description of some new Cacti and Mammillariz, recently brought from Mexico by Mr. Buiiock of the Egyptian Hall, Piccadilly ; and now preserved, with many other very rare Plants, in the Nursery of Mr. Tate, in Sloane-street. By A.H. Haworrn, Esg. FLAS. Sc... . 40 An Account of the Effect of Mercurial Vapours on the Crew of His Majestis Ship Triumph in the Year 1810. By WiLL1AM Burnett, M.D., one of the Medical Commissioners of the Navy, formerly Physician and scrimnagh of a to ee Mediterranean Fleet. . Account of a Work entitled < Storia de’ Fenomeni del Vesuvio avvenuti negli anni 1821, 1822, e parte del 1823,” etc. “* Fiistory of the Phenomena of Vesuvius during the Years 1821, 1822, and Part of 1823; accompanied with Obser- vations and Experiments. By J. MontTice.ui, Perpetual Secretary of the Royal Acudemy of Sciences of Naples ; and N. Cove tut, of the Royal Institute of HN TN By M. Menarp DE LaGnoye . : ; Vol. 63. No. 314, June 1824. a CONTENTS. On the ensuing Oppositionof Mars. By ¥. Batty, Esq. F.R.S. Read before the Astronomical Society of London, January a UA ces piste\co oul nue Ty oleh. a0 t wollp. etapa wart 9 sc se ns Remarks on the Position of the Upper Marine Formation exhi- bited in the Cliffs on the North-east Coast of Norfolk. By Mr. Ricuarp Tayitor of Norwich . . ... .- 81 On the Mode of manufacturing Salt by Evaporation on Faggots. By R. BaKeweEt, Esq. . 2 2). ss se es 86 Description of a Pressure Gauge recommended for its Simpli- city of Construction and Principle; with Observations on the Gauge proposed by Mr.Seawarp. By Mr.H. Russert 92 Electro- and Thermo-magnetical Experiments. By Mr. Wo. SURGEON: (2's © 2\5, Duval att inlet oral, isle bk ee On Parallel Straight Lines. By Joun Wausu, Esq. 100, 271 A technical Description of Chloraster, a new Genus of Nar- cissex. By A. H. Haworrtu, Esq. F.LS. $c. . . 102 Papers relating to the Earthquake which occurred in India in — 105, 170 US 19 sxc cdr icnt Nesemere hfe’ wee en) ben. Le On White Copper. By C. Kererstein. Read at a Meeting of the German Explorers of Nature at Halle, September 18, 1823..... ae oi) | Experiments on the Deviation of the Magnetic Needle, as effected © by Caloric, &c. By Joun Murray, Esg. F.S.A. F.L.S. F.H.S. Member of the Geological and Wernerian Societies, GGA. OTA AG TRU YER LAE SS) Description, Analysis, §c. of a Lamellar Pyroxene. By Larp- NER VANUXEM . 2 Poe On the Application of Algebraic Functions to prove the Proper- ties of Parallel Lines. . 161 Experiments on the Adhesion of Nails. By B. Bevan, Esq. 168 ~ On the Circular Micrometer. By ¥. Batty, Esq. F.R.S. 177 Mineralogical and Chemical Examination of Hyalosiderite, a new Mineral. By Dr. Waucuner, of Freiburg in the Breis- BAG eg we ee 8 IS Oe ee ee On High-pressure Gauges. By Mr. Samurt Seawarp 190 Memoir on the Variations of the reflective, refractive and disper- sive Powers of the Atmosphere, §&c. By 'T. Forsrer, M.B. F.L.S. Member of the Astronomical and the Meteorological Societies of London, and Corresponding Member of the Aca- demy of Natural Sciences at Philadelphia, &c. . . 192, 328 Description of a new Micrometer. By M. FRAUENHOFER of Mamnicle gai 095. WHA NS PEO SSO. ME ae Letter fron Rosert Hare, M.D. Professor of Chemistry in the University of Pennsylvania, to B. Sittiman, Professor of Chemistry in Yale College, on some improved Forms of the Galvanic Deflagrator ; on the Superiority of its deflagrating CONTENTS. Power: also, An Account of an improved Single-leaf Electro~ meter ; of the Combustion of Iron by a Jet of Sulphur in Va- pour; and of an easy Mode of imitating native Chalybeate deg) pia, Se ES LR en a Se a OR Further Remarks on the Theory of Parallel Lines. . . 246 On the Mathematical and Astronomical Instrument Makers at Paris. By Lieuwt.ZaurtMann . . . . 2. .) 959. Suggestions regarding some probable Sources of Error in the usual Modes of ascertaining the Force of Steam. . . 259 Remarks on an Article published in No. 23 of the Journal of Science, and treating of the New Tables of Refraction. By BINORY, Piso. MLA eR, 3. te, ts cc BEF Description of a Rotative Thermo-magnetical Experiment. By - Mr. Wittiam SturcEon| . . . ww... 969 Soological Notices. By Mr.Joun Epwarv Gray . . 274 Analysis of Professor HausMANN’s Essay on the Geology of the MEE cn, aut eae yon, Ce te het eee Chemical Examination of Green Feldspar from Beverly, Mas- sachusetts. By J. W.Wesster, M.D. . . . . 9899 Descriptions of several new Species of Ascidia. By C. A. Lr- nse ie ne so ng we oer a. Wee a, ee Dissection of a Batrachian Animal in a living State. By Rr- cHarD Haran, M.D. Professor of Comparative Anatomy to the Philadelphia Museum ee yee ee Tey Remarks on the Theory of the Figure of the Earth. By pa Tvony, Esq: MA. FURS.) isepoRl Srey 339 Examination of the Divisions of ReicHEenzacn’s Circle at the Observatory of Kinigsberg. “By M.Brsse. . . . 348 On Mr. Bassace’s new Machine Sor calculating and printing Mathematical and Astronomical Tables. From Francis ee, Pays Poe De ee ee . Sos A brief Account of some Electro-magnetic and Galvanic Er- periments. By Rosert Hare, M.D. Professor of Chemistry in the University of Pennsylvania . NEN SE TEIN On the Circle. By Joun Watsn, EG. 5" nce ts yeh sda On a Method of finding the Limits of the Roots of the higher Powers of Numerical Equations. “ By Mr. J. Rowsoruam 369 On the Application of the Term “Infinite” . . . , Sie Two Lines from the Nautical Almanac, addressed to Mr. Ivory. 374 An Account of some Experiments made in order to deter mine the Velocity with which Sound is transmitted in the Atmosphere. By Ouintuus Grecory, LL.D., Secretary of the Astronomical Society of London, and Professor of Ma- thematics in the Royal Military Academy at Woolwich 401 CONTENTS. On the New Method of Gauging proposed by Dr. Younc. By Rin Wa WAsEM AN > 2 OO es 1 aA Letter on the Astronomical Refractions. By J. Ivory, Esq. A, TORS... 3. oe oes Stes 0 a ot) ata e™ se ee On some Errors in Dr. Hurron’s Tables of the Products and Powers of Numbers. By Mr. James Urtinc . . . 427 Introduction to the Sixth Section of Bessrx’s Astronomical Ob- PETMEHANGS. GS -SPNO OUBES N, OAS SS ee Some Account of the Binomial Calculus. By J. Wausu, Esq. 443 On Black Currant Wine. ByC.G. Harty, Esg. . . 446 Notices respecting New Books 52, 135, 219, 284, 375, 447 Proceedings of Learned Societies 59, 136, 224, 299, 378, 452 Intelligence and Miscellaneous Articles 63, 140, 230, 307, 392, 459 List of Patents . . . . . 75,148, 239, $19, 399, 471 Meteorological Tables . . +: «~ 75, 149, 240, 320, 400, 473 PLATES. I, Section of Cromer Cliff. Il. Dr. Watcuyen’s Figures of the Crystals of Hyalosiderite. II]. Faavennorer’s Micrometer. IV. Dr. Hane’s Single-leaf Electrometer, and improved Deflagrators. V. Amphiuma means: Ascidia plicata: and Ascidia ovalis. ERRATA: Page 60, line 20 from bottom: for “ William Scores, Jun. Esq.” read ‘ Wil- liam Scoresby, Jun. Esq.” Page 60, line 6 from bottom: for “ Walross’’ read “ Walrus.” _ Page 97, line 17: for ‘the platinum is positive to the silver” read “ the silver is positive to the platinum.” Page 236, line 20 from bottom : for “ Meissin’’ read “ Meissen.” Page 268, line 5: for 400°” read “ 100°.” Page 305, line 4 from bottom: for “ M. Guillon” read “ M. Gaillon.” Page 306, line 22: for“ M. Le Galloias” read “M. Le Gallois, Jun.” Page 306, line 12 from bottom: for “ M. Giraud” read « M, Girard.” Page 306, line 5 from bottom: for “ M. Remain” read “ M. Romain.” Page 307, line 5: for “ Arnaud Reynaud” read “ Armand Reynaud.” Page 307, line 7: for “ M. Tilerier” read “ M. Tilorier,” Page 394, last lines for “ Irkutak”® read “ Irkutsk.” THE PHILOSOPHICAL MAGAZINE AND JOURNAL. 31* JANUARY 1824, I. On two new Species of Narcissus. To the Editors of the Philosophical Magazine and Journal. Gentlemen, WHEN you published in yourlast Number, p.440, Mr. Ha- worth’s excellent account of a new Genus of Narcissea, you were not aware that the two species there noticed had been described, and one of them actually figured, in The Botanical Register, as new species of Narcissus, with specific names un- der which they have been known and distinguished for the last two years, and which I am persuaded Mr. Haworth has no desire to change. The Diomedes minor of Mr. Ha- worth is Narcissus Macleayi of the Botanical Register. This plant appears to have been long lost to our gardens until re- cently imported by the Secretary to the Linnzan Society, among other bulbs, from Smyrna. Mr. Haworth’s D. major is figured in the Botanical Register, and named Narcissus Sabini, in honour of the worthy Secretary of the Horticultural Society, whose thorough knowledge of the genus fully entitles him to this distinction, independently of the circumstance of his having recently restored this species to the notice of British botanists. Whether the beautiful genus of Narcissus ought to be divided into many genera, must be left to botanists to decide; but I suspect that Dzomedes will not be considered a good name for a genus of plants, as being not sufficiently distinct from the genus Diomedea of Linnzeus. Yours &c. E. E. Vol. 63. No. 309. Jan. 1824. A 2 II. On Ss a II. On the irregular Indications of Thermometers*. By Joun Herapata, Esg.t "THE first time I noticed any irregularity of thermometrical indication, was in the summer of 1820. Holding the thermometer of a friend obliquely, with its bulb in boiling water, and then raising the stem to a vertical position, I re- peatedly observed that the latter position gave a highs indi- cation than the former. This, as far as I remember, happened only when the thermometer was first put in the water obliquely, and then brought to a vertical position; but I do not recollect whether any iene happened when the position was first vertical and then oblique; nor do. I indeed remember that such a case was tried. My friend having at the time treated my observation as accidental, and due to the greater influence of the ascending steam on the vertical than on the oblique tube, turned my attention to a different object; though the least consideration of the thickness of the glass and the very slow transmission of heat by this body, ought to have con- vinced us that such a reason was incorrect. I have no pre- cise recollection of the obliquity of the tube, or of the amount of the difference of the indications; but I rather think the de- clination from the vertex was about 30°, and the difference of. the indications a degree or two. The thermometer, as far as I remember, was rather large in the calibre. Some months after this observed, in the course of some experiments on the resulting temperatures of equal portions of mercury differently heated, that the thermometer with which I took the higher temperature often sunk, in taking imme- diately afterwards that of the mixture, from a half to a whole degree lower than that to which it quickly rose and settled. _ My attention being shortly afterwards more particularly di- rected to the correction of thermometers, I resolved to under- take a few experiments for the purpose of discovering a guide to a more practically accurate correction than that usually given. L£xp. 1.—I put the bulb of a thermometer which was about * It has been imagined by some scientific gentlemen into whose hands a friend put this paper, that my object is to support the theory of Bellani. ‘This opinion they formed from my having made, as they say, an erroneous quotation of his experiment; owing to my relying on a hasty mental im- pression enfeebled by a considerable lapse of time. I beg however to ob- serve, that I never had an idea of supporting Bellani’s views. My present ideas of thermometrical corrections had occurred to me some years before Siguor Bellani published, or perhaps made, his experiment ; and my allusion to it was for the purpose of showing, that, from the impression I had of the experiment, Bellani erred in discovering the cause of his phenomenon. + Communicated by the Author. 50° Mr. J. Herapath on the Indications of Thermometers. 9 50° Fahr. gradually into mercury at about 350°. After the thermometer had risen as high as it would, I took it out, and rapidly cooled down the bulb by means of a wet cloth to within about 50° or 70° of 212°. Plunging the bulb im- mediately into water rapidly boiling, I observed the mercury descend to a certain point; and then regularly, but somewhat quickly, rise and settle from a degree to a degree and a half higher. I could not ascertain the exact ascent, in consequence of the divisions of the scale comprehending each not less than two degrees. Exp. 2. Having first cooled down the stem and bulb, by immersing the instrument for some time in water of about 50°, I put the thermometer as before into mercury of 400° or up- wards. Suffering it to become stationary, it was taken out, and the bulb cooled, by similar means to that in the last ex- periment, to about 300°, and then immersed in the same water boiling very fast; a like rise took place, after the mercury had sunk to its minimum, but as I fancied a little greater ap- proaching nearer to two degrees. An accident at the close of this experiment unfortunately destroyed the thermometer I used, which happened to be the last I had left that extended toa high range. This prevented me from trying other similar experiments on a more careful and varied plan. The instrument ranged from about — 100° to nearly + 500°; and its bulb extended 3-4ths of an inch or more below the scale. After the lapse of a considerable period, I recollected that I had a thermometer by me, which, though not very good for measuring great intervals of temperature, on account of the irregularity of its calibre, was nevertheless, from its sensibility and range, well suited for delicate experiments of this kind. It extended from about —44° to +-106°, and was so sensible, that the temperature might be read off to the 1-15th of a de- gree, or even to the 1-30th with great care. Its bulb projected three inches beneath the scale. With this instrument I made the following experiments *: Exp.7. Leaving my thermometer and 16865 grains of mer- cury ina glass tumbler, weighing 2835 grains, for about twelve hours in the same room, I took the temperature of the mercur at 51°-27, the air being 52°. Putting the bulb immediately ak terwards in water of a much higher temperature, I allowed the thermometer to ascend to 105°. As I could not safely venture to raise the mercury higher, I took out the instrument, suffered it to cool a few degrees, and then reimmersed it. This I did * The intermediate experiments, and the 11th, have been struck out by the author for the sake of brevity ; but their mean results are included in the general balance. Vol. 63. No. 309. Jan. 1824. B two 10 Mr. J. Herapath on the irregular , two or three times, by which I thought I should produce the samie effect on the thermometer as if I had allowed it to reach its maximum in water of about 105° or 106°. Cooling down the bulb considerably, I observed the mercury to be 51°47, exceeding apparently its former temperature by °2. Exp.8. Being apprehensive that I might have raised the temperature of the mercury a little, by the excess of the tem- perature in the bulb at the time of the re-immersion, I re- peated the experiment at the distance of 12 or 24 hours in precisely the same way, except that I brought the bulb, pre- vious to taking the second temperature, to as near as I could this mercurial temperature, by putting it in water and then quickly wiping it dry with a handkerchief. The air being 50° near the wall, the numbers were 48°53 and 48°°67. Exp. 9. Twenty-four hours afterwards the same apparatus and precautions gave 45°°93 and 46°°10, the air being 46° 7. Exp.10. At the end of 12 or 24 hours more, in an atmo- sphere of 47°, I obtained 46°2 and 46°°4. Exp.12. Being desirous of trying the experiment so as to ascertain whether immediate repetitions with mercury would be attended with successive augmentations of temperature, I put my glass containing the mercury in the same room with my thermometer. About four hours afterwards, the air near one of the walls being 48°5, I repeated the experiment with all the preceding precautions, to which I added that of cool- ing the thermometer’s bulb, previous to the last immersion, a degree lower at least than the mercury. The numbers were 48°°5 and 48°73. A few minutes afterwards I raised the thermometer again to 105°; and, with the same care in cool- ing the bulb a degree or more beneath the mercury, took the mercury at 48°83, Another repetition with like precautions gave 48°°9, and another 48°°97. These experiments alto- gether occupied about 20 minutes. Half an hour after I had finished I observed the same thermometer near the wall stand at 48°°8; the mercury indi- cating by this instrument a temperature of 48°87. Exp. 13. ‘Twenty-four hours afterwards, the air being 48°:47, I repeated the experiment with the same care and precautions. The numbers were at 8" 40’ A.M. before heating thermom. 47°47 AB eS after Tditto: iit 2 oe tele PT A sot after 2/2. dittoc? 2009.0) 47998 50....... Sdditto. .-... 48°07 55.4.4... 4thditto..... 48°20 O....... Sthditto. ..., 48°40 5se-.... Gthditto..... .48 60 D iid LO ake sort TEM GIO, . eS OeeA COODRDKRAM the Indications of Thermometers. 11 the bulb having at each repetition, after being raised to 105°, been cooled down to 47° or lower, and quickly and carefully wiped with a silk handkerchief before retaking the tempera- ture of the mercury. In consequence of the weather being fine, its temperature manifestly increasing, and the mercury at first so much colder (one degree) than the atmosphere, I concluded that the suc- cessive augmentations of temperature observed in the mercury at the several repetitions of the experiment, were due rather to the gradual rise of this body’s temperature than to any continued increase in the indications of the thermometer. As a confirmation of this, I observed that the temperature of the air and mercury taken at 9° 40’, or one hour after, was 49°°8; which, compared with the temperature of the mercury at the first and last of the preceding observations, shows nearly a uniform increase of 2°°2 per hour after allowing for the excess of the apparent above the real indication in the observation at 9° 10’. Deducting therefore from all the observations except the first a quantity proportional to the time, at the rate of 34, of a degree per minute, the observations will stand, corrected for the increase of the mercury’s temperature, as below: Dts. saa cua DEE in ntncetatih uo Fede wet: Aun Gs GEA oh oisse ch tn eGl BL ah Bianco hl cEuk MN 6 ik 82 oh Ae Fe GS MED 8 Ss nine Age pO thi... sites ety This experiment seems to show that the difference of indi- cations in the thermometer is produced at the first heating of the bulb, and not increased by any following similar opera- tions. Exp.14. During the preceding experiments I was near the mercury at the times only of my taking its temperature ; at other times I was many feet from it; and not unfrequently several things stood between me and it, so as to cut off all rectilinear communication. But having after the last experi- ment observed that the heat of the body, when standing within about two feet from the unprotected glass, raised the tempera- ture of the mercury in one instance as much as 3-10ths of a degree in 5’, I was desirous of repeating the experiment un- der circumstances in which this proximity could have no effect, or at least no sensible effect. For this purpose I ob- tained the assistance of my friend Mr. Mervyn Crawford, to whose precision the accuracy of the following experiments is much indebted. The mercury having been for several days in our experi- B2 menting 12 Mr. J. Herapath on the irregular menting room, I formed about three hours before we began all round the glass, but not touching it, a close thick wall of books, rising from two to three inches above it. At 8 22’, the mercury was 46° 23', and at 9° 10’ the air 46°13. At this time we commenced our experiments, going through the usual process of heating and cooling the bulb (to 46°°2) before taking each temperature after the first. Times. Mercvvial Temp. 95 104 46°°17 O'NTS 46 °33 9°19 46 °30 9 232 46 °33 9 27 46 °33 Wishing to know whether the air and mercury for a short time afterwards varied their temperatures much, I observed with the same instrument, without any heating or cooling, at gh 39! the merc. was 46°33 the air 46°°13 9 37 ....% 46°40 °° 46 °80 going out and returning at9 52 ..... 46°53 .. 46°80 Exp. 15 and 16. Another experiment made with a closer and higher wall of books gave a similar result (13. Varying the experiment so as to measure the temperature of the mer- cury with the thermometer in the same state a second. time, before each repetition of heating, had the advantage of show- ing the real alteration of the mercurial temperature at equal intervals, during the course of repetitions. No difference however having been found in the general value of anomalous indication, it is unnecessary to enter into details. In this last experiment I used water for heating the ther- mometer, which was only 106°; in which I put the bulb, and let it remain for about 5 minutes to see whether any difference in the result would arise from the water being of a less tem- perature than before. The difference of indication came out, however, nearly the same, ‘17 or rather more. The mean difference of indication in all these experiments, after allowing in the 12th for the advance of temperature, is about 174; the air and thermometrical tube being about 50°°7, or in round numbers 50°. During the making of the preceding experiments I made one or two efforts likewise to ascertain whether any difference existed in the indications, by first immersing the bulb in water of 105° with the stem oblique, and then raising it to a perpendicular; but, for want of a steady temperature in the water, I could not succeed. On inquiring into the cause of the phamomena I have de- tailed, Indications of Thermometers. 13 tailed, we are instantly led to attribute it to the recommuni- cation, from the glass of the stem to the colder descending portion of mercury, of a part of that heat which had been communicated from the warmer portion of the ascending co- lumn. Were the bulb at every instant uniformly of the same temperature, the successive portions of mercury which ascend into the stem from the bulb would be successively higher in temperature than those which precede or are above them; and the temperature of all that had ascended from the bulb would be less almost in the precise proportion to the distance from the bulb. But, from the quick conductibility of mer- cury, it seems probable that there is a rapid and continued transmission of temperature from the bulb to the higher parts. And, in consequence of the little affinity between mercury and glass, this transmission may be aided, when the stem is verti- cal, even by the ascent of the warmer portions, on account of the difference in the specific gravity. However this may be, it is plain that the mercury being warmer than the stem, must communicate a portion of its excess of temperature to the glass. ‘The loss thus sustained by the mercury will be shortly made up by further transmission from the bulb. In the course of a very few transmissions in this way, that is, in a very short time, the interior of the glass to a small depth from the co- lumn of mercury, will attain a temperature equal or nearly equal to that of the adjacent mercury; provided the tempera- ture of the bulb remain nearly the same. Suppose now the bulb to be cooled, the mercury in the stem which occupied the higher will descend to the lower and warmer parts, and if this descent be very rapid it may exceed in celerity the tardy communication of heat from the sur- rounding glass; so that the column of mercury at the instant it becomes stationary, is colder than the glass enveloping it. An expansion, therefore, and a consequent rise in the mer- curial column will gradually ensue by the communication of a part of the excess of heat in the contiguous glass. This phee- nomenon would be similar to that in the first two experiments. Should the bulb be brought back after being heated to its primitive temperature, it is plain that the suspended column of mercury, though precisely the same in quantity, yet being by the heated glass raised in temperature, will settle to a higher indication than before. This is the phaenomenon con- tained in the 14 last experiments. The amount of this variation of apparent temperature mani- festly depends, in either case, on the difference of the second and last temperatures of the bulb, and the length of the column of mercury in the last temperature. If these remain the same, a repetition 14 Mr. J. Herapath on the Indications of Thermometers. a repetition of the heating and cooling process immediately afterwards would therefore produce no difference in the amount of the variation, provided sufficient time was given in the first process for the mercury to obtain from the bulb, and com- municate to the glass, the necessary quantity of heat, accord- ing to the distance from the bulb. For like reasons a third, fourth, &c. process immediately afterwards would not alter the value of the variation. Hence the reason that the 12th and subsequent experiments did not exhibit any difference in the apparent temperatures at the 3d, 4th, &c. observations ; proper allowance being made for the real variation of the mercurial temperature during the intervals. With respect to the time required in the first heating and cooling of the mercury to give the maximum effect, I have not made any observations; but, from a circumstance or two that occurred in the course of my experiments, a much shorter period than I took would produce a sensibly less variation. Nor have I determined in how long after such an experiment alike variation may be observed with the same instrument; but I conceive that a half hour’s careful cooling of the stem would be sufficient, or less if the stem could be well cooled in a less time. It can hardly be expected of me, with so few experiments, to enter into a theoretical computation of the value of this variation under all circumstances. If however the views that I have taken of it be nearly correct, the variation would be about half the mercurial correction for the same column of mercury at the 2d and 3rd temperatures of the bulb. Now the correction given by the Royal Society’s Committee is = —=—______——_— minus } of this value. Call- ing, therefore, in round numbers the range of the last ther- mometer from —40° to + 100°, and supposing the mean tem- perature of the bulb to have been 50°, we shall have for the general correction 40 + 50) x (100— 50 p, C0490) x (1007 90) — 7 (-45) = 3938 ; the half of which, or °°197, ought to be the amount of varia- tion. Our experiments give *17. Again: supposing in the first experiment there were about 20° or 22° of the lower degrees immersed, which I should think there were though I did not attend to it carefully, the correction would be 7, CERCA 1) = 14°06) = 3°553. Half Dr. Wollaston on the Magnetism of Metallic Titanium. 15 Half of this 19°77 should be the amount of ascent, which does not differ much from the experiment — a degree or a degree and a half. The difference is also on the night side; for we might easily conceive that the mercury is heated a little as it comes down, and consequently does not sink so low as it otherwise would, nor therefore afterwards rise so much. A like calculation for the second experiment would give about 2°4. This differs also from observation on the side we might expect, but more than the preceding calculation. It is remarkable that if we take a number to 1°77 as *17 to -197, it will be 1°-5, as nearly as possible that which was ob- served in the first experiment; and if we take a number to 2-4 as 17 to *197, it will be 2°1, differing also but very little from the second experiment. From this it appears that our theoretical value is too high by about an eighth. Before, however, much can be said with certainty, other and more extensive experiments are wanting. But enough, I hope, has been advanced, to show the danger of relying, in delicate ex- periments, on the correction usually employed for that part of the tube not immersed in the fluid. London, Cranford, May 7, 1823. III. On the apparent Magnetism of Metallic Titanium. By Wiiu1am Hype Wottaston, M.D. VAP Tes.” N an account that I lately gave of the properties of metallic titanium, which is printed in the First Part of the volume of the Philosophical Transactions for the present year+, there is an oversight, which I am desirous of rectifying as soon as may be. I have there stated that the cubic crystals of ti- tanium, when first detached from the iron-slag_ where they are found, were all attracted by a magnet, but that when they had been freed from all particles of iron adherent to them, they appeared to be no longer acted upon by it. Having since that time been led, by the observations of M. Peschier of Geneva, to examine this question more accu- rately, I find that, although the crystals are not sufficiently attractile to be wholly supported by the magnet, yet when a crystal is supported by a fine thread, the force of attraction is sufficient to draw it about 20 degrees from the perpendi- cular, and consequently that the force of attraction is equal to about one-third the weight of the metal. When a piece of soft iron of about the same size was made of a cubic form (weighing half a grain), the attractive force * From the Philosophical Transactions for 1823, Part Il. + See Phil. Mag. vol. Ixti, p. 18, of 16 Dr. J. W. Webster’s Examination of the iron to the same magnet was found, in successive trials, to lift from eighty to ninety times its weight of a silver chain adapted to this inquiry. By a similar mode of trial, I found that cobalt carried from fifty to sixty times its weight, and that.a similar quantity of nickel supported from twenty to thirty times its own weight by the same magnet. From the above comparison of the magnetic forces, it is evident that the presence of about 71, part of iron as an alloy in the metallic titanium, would be sufficient to account for this power, without regarding titanium itself as a magnetic metal; and its origin in the midst of iron gives every reason to suspect that it would be contaminated by some proportion of that metal. It is, however, extremely difficult really to detect the pre- sence of so small 2 proportion of iron, on account of the high colour of the precipitates of titanium. For though it may be easy to produce an appearance of blue by using a prussiate, which already contains iron, and is consequently better adapted to prove the absence of iron where no blueness appears, than to ascertain its presence, it is by no means easy to obtain the more indisputable evidence of iron by infusion of galls. It is only by repeated evaporation of the muriatic solution, and continued exposure of the residuum to the temperature of boiling water, that I have succeeded in separating enough of the titanium to allow the blackness of gallate of iron to ap- pear, when the efflorescent edges of the dried salt are touched with infusion of galls. Although the quantity thus rendered sensible does not ap- pear in proportion sufficient to account for the magnetic force observed, there seems more reason to ascribe it to this im- purity, than to suppose titanium possessed of that peculiar property in a degree so far inferior to the other known mag- netic metals. IV. Chemical Examination of a Fragment of a Meteor which fell in Maine, August 1823. By Joun W. Wesster, M.D. M.G.S. Lond. &c.* THIS aérolite fell at Nobleborough in the State of Maine, on the 7th of August 1823, between four and five o’clock p.M. The only infcrmation which I have been able to obtain of the attending phznomena is from the papers of the day, __ * For this communication we are indebted to the kindness of the author, in the ensuing Number of whose Journal of Philosophy and the Arts, pub- lished at Boston, U.S., it will be inserted. and of a new American Meteorite. 17 and from a communication of Professor Cleaveland, which is published in the American Journal of Science, vol. vii. p. 170; this account he informs me was obtained at his request by a gentleman of intelligence in a personal interview with Mr. A. Dinsmore, who was at work near the place where the aérelite struck. ‘ Mr. Dinsmore’s ‘attention was excited by hearing a noise which at first resembled the discharges of platoons of soldiers, but became more rapid in succession. The air was perfectly calm; and the sky was clear, with the exception of a small whitish cloud, apparently about forty feet square, nearly in his zenith, from which the noise seemed to proceed. After the explosion, this little cloud appeared to be in rapid spiral motion downwards, as if about ‘to fall on him, and made a noise like a whirlwind among leaves. At this moment, the stone fell among some sheep, which were thereby much frightened, jumped, and ran into the woods. This circumstance assisted Mr. D. in finding the spot where the stone struck, which was about forty paces in front of the place where he was standing. The aérolite penetrated the earth about six inches, and there meeting another stone, was broken into fragments: When first taken up, which was about one hour after its fall, it exhaled a strong sulphureous odour. The whole mass previous to-its fracture probably weighed between four and six pounds; other fragments of the same meteoric stone are said to have been found several miles distant from Nobleborough.”— Amer. Jour. To the politeness of Dr. George Hayward I am indebted for a fragment of this meteor. Externally the specimen was in part covered with a thin semivitrified crust or enamel of a black colour, the surtace of which was irregular and marked with numerous depressions, presenting every appearance of having been subjected to in- tense heat. The crust was hard, yielding with difficulty to the knife. The quantity of this crust which the small frag- ment I obtained afforded, was not sufficient to allow of any separate analysis of it. The mass of the specimen had a light gray colour inter- spersed with oblong spots of white, having the aspect of decom- posed leucite, and giving it a porphyritic aspect. ‘Through- out the stone minute points of a yellow substance, resembling olivine, were distributed, with microscopic points of a yellow colour, which I imagine were sulphuretted iron. ‘The cement by which these substances were united was of an earthy aspect, and soft texture, readily broken down by the fingers. The general appearance of the mass was precisely like that of some of the volcanic tuffas. Vol. 63. No. 309. Jan. 1824. C The 18 Dr. J. W. Webster’s Examination. The specific gravity was remarkably low, being but 2-05 *. Before the blow-pipe it exhaled a sulphureous odour, but was not fused. The specimen was reduced to powder and submitted to the action of a magnet of considerable power, but no attractable particles were separated. A portion was heated to redness on a platina spoon; it emitted the sulphureous odour, and its weight was diminished rather more than 21 per cent.; the re- sidue acquired a brown colour; it was again presented to the magnet, but nothing was attracted. (1.) One hundred grains of the stone were introduced into a tubulated retort with dilute muriatic acid; the beak of the retort was plunged into a solution of acetate of lead, slightly acid, and contained in a small tubulated receiver. A mo- derate degree of heat was applied, and the digestion continued for twelve hours. A slight quantity of eo ee of lead was formed, but not sufficient to admit of being collected and weighed. All action upon the powder having ceased, the fluid was turbid, apparently holding a substance which I imagined to be the sulphur in suspension; at the bottom was an undis- solyed residuum. (2.) The fluid was carefully separated and filtered ; the sub- stance remaining upon the filter was washed with distilled water, and thoroughly dried; it proved to. be sulphur, and weighed 18-3 grains. (3.) The insoluble residuum was mixed with pure potash, and exposed in a silver crucible to heat sufficient to cause the fusion of any siliceous earth. The crucible being placed in an evaporating dish, hot distilled water was poured upon it until the contents were completely removed. The resulting fluid was treated in the usual manner with muriatie acid, with the addition of the acid which had been digested upon the stone in the first instanee. ‘lhe quantity of silex obtained after calcination amounted to 29°5 grains. (4.) The solution, the bulk of which had been considerably augmented by the addition of the water with which the pre- cipitate (3) had been washed, was carefully evaporated to rather less than a pint. Carbonate of potash was added until it ceased to produce any precipitate; the whole was mode- rately boiled. When the precipitate had completely subsided, the supernatant liquor was decanted, and distilled water sub- stituted. The precipitate was collected and boiled with pure potash ; the liquor after filtration was treated with muriatic * The lowest specific gravity of any meteorolite on record, is that of the St. Etienne specimen, which is but 1°94. acid of anew American Meteorite. 19 acid in excess, from which carbonate of ammonia threw down a flaky precipitate, and was added until the alkaline taste predominated. The precipitate thus obtained, after ignition weighed 4°7 grains. To satisfy myself of the nature of this substance, it was treated with sulphuric acid and potash; cry- stals of alum were obtained, and it was therefore alumina. (5). The residuum which had resisted the action of the potash was digested in diluted sulphuric acid; after expelling the excess of acid, pure water was poured upon the remaining solid, in order to dissolve any sulphate of magnesia and me- tallic sulphates. To discover if any lime was present in the solution, it was treated with alcohol, which afforded a slight trace of that earth. (6.) The solution, after the addition of more water, was acidulated with sulphuric acid, and the metallic oxides were precipitated by the bicarbonate of potash. The magnesia was separated by pure potash, and after ignition weighed 24°8 grains. ; (7.) The precipitate (6) was boiled im nitric acid, in order to convert any chrome present in it into an acid, which was afterwards by the addition of potash converted into a soluble chromate. On adding muriatic acid, the chrome was obtained in the state of an oxide, sufficiently characterized by its beau- tiful colour. After being well dried it weighed 4 grains. A portion of this substance was subsequently exposed on charcoal with borax to the action of the blow-pipe, and its nature satisfactorily proved. (8.) The matter remaining after the separation of the chrome was redissolved in muriatic acid, and the iron was thrown down by ammonia. After washing and drying, it weighed 14°9 grains. (9.) The remaining solution was now evaporated, the am- monia driven off, and the precipitate, which proved to be nickel, weighed 2°3 grains. The composition of this meteoric mass is therefore Sulphur ......cccccossevsenee 18°S Silex’. .visscsda ashi sscetve) 295 AlumiINa seocsscavesessedrsee 4°7. Lime 62s..csssseecesesessccsee & trace Magnesia...coccscrsceesereee 248 Chrome s1<.ccc.edcccssovssss | 4° Wnonisixetedd..s.cstledsasticiln) B49 Nickel ..cdcsiswstessecesecsiv)! 2°S 98°5 Loss.sces6 1:5 100° C2 V. A new [ 20 J Vid new Theory of Telescopes founded on rational Principles and interesting Experiments. By J. Reavr, M.D.* OOKING on the corneal theory of vision as established, in this paper I shall endeavour to apply that theory to practical advantage in the science of astronomy. Although I have shown, by numerous and I may venture to say con- clusive experiments, that our ideas of objects are produced by erect images painted on the pupil, still 1 by no means argue that the retina is not the nerve communicating with the sen- sorium, in a similar manner as the nerves minister to feeling, hearing, tasting and smelling. Indeed, the five senses may be all reduced to one, the sense of feeling. So long as philo- sophers believed that inverted images painted on the retina produced the phenomena of vision, so long the most incon- sistent opinions were advanced of long-and short- sightedness, and the theory of telescopes, spectacles, &c. ‘If the cornea or crystalline (say authors), or either of these, be too flat, a pencil of light coming from an object at an ordinary distance will have its focus at some point beyond the retina, and there- fore vision will be indistinct, as in the case of an object too near for a common eye.” Let us for a moment examine this reasoning. It is admitted on all hands, that no inverted image is ever formed, until the rays cross after arriving at the focus; consequently, if the focal point were situate beyond the retina, no image could ever be painted on that substance, and we must be driven to the absurdity, that the mind could perceive an object without an image. Dr. Porterfield has some strange metaphysical ideas on this subject, at one time talking of pictures on the retina, and the next moment deny- ing their existence. Having examined the eyes of many short- sighted persons with much accuracy, I find them not to differ in the least from long-sighted eyes; hence the flatness or plumpness of the cornea can have nothing to do with the dis- ease, however necessary it may be to the refracted theory of philosophers. Here I may enlarge on this subject, but must refer to a former paper in your valuable Journal}, wherein I have ex- perimentally demonstrated that focal images are not formed by any crossing of the rays, when passed through a lens, but that the focus is produced by reflected images uniting, and sent from the concave sides. Indeed, I am inclined to think that we must look to the nerves for the cause of short- sightedness, and not to any fanciful flatness or plumpness of * Communicated by the Author. + See Phil. Mag. vol. viii. p. 249, and vol. lix. p. 200. h the Dr. J. Reade on a new Theory of Telescopes. 21 the cornea. For on an analogy with the other senses, such as feeling, hearing, tasting, &c., we find extreme stimuli act so as for a time to injure the organ, and in a manner to pa- ralyse sensibility. Thus a soldier returning from the field of battle, and deafened by the roar of cannon, for a time be- comes insensible to minor sounds. ‘The fingers accustomed to rough usage, are incapable of nice works; and in like manner the retina accustomed to the stimulus of light sent from very close objects, by degrees adapts itself and becomes insensible to those more remote, and consequently less powerful. On similar principles, a person with the best sight may make him- self short-sighted, by merely wearing concave glasses. I have met with some simple young gentlemen at College, who pro- duced the disease by this affectation, and became perfectly short-sighted. It is well known that watch-makers are short- sighted, and sailors the reverse. A long-sighted person may become short-sighted in a week, or after a fever, or a nervous disease, without any change of the cornea or crystalline lens. Nor can I conceive that wearing a concave glass could after any time change the shape of the cornea. For the purpose of particularly investigating this subject, I requested a very short-sighted gentleman to seat himself opposite the letter T pasted on the window, as already men- tioned in my paper.On Vision, published in the Annals of Philosophy ; and on looking at the correct reflected image on the pupil, and comparing it with that of a long-sighted per- son seated at the same distance, I could not perceive the Jeast difference either in the size or strength of colouring; yet the long-sighted gentleman saw the letter distinctly, while the other said that he only saw a very confused and large outline. Hence we must infer that the disease lies not in any plump- ness or flatness of the cornea, but in either the humours or the nerves, or both. A convex glass increases the confusion with a short-sighted person, and therefore is never used ; with a long-sighted person it renders the object more distinct. By the interposition of a concavo-concave glass, an image is formed very near the eye, which, although small, sends the rays with as much force to the cornea, as if the object itself were in the same place: short-sighted people choose a small print, write a small hand, and take off their spectacles when reading. Much has been written to very little purpose on the means of finding the foci of spectacles, and philosophers have exerted all their ingenuity; yet the practical optician, however qualified to read their learned essays, throws them aside for the old-fashioned and purely mechanical method of holding the lens before a wall, and measuring the focus te a rule: 22 Dr. J. Reade on a new Theory of Telescopes. a rule: yet it must be allowed that on a subject of such im- portance to the happiness of mankind, such a method is very unsatisfactory, and often leading to an injury of sight, for two convex or concave spectacle glasses may be very dissimilar in transparency or quality of glass without in the least affecting the focal images ; this may be shown by scratching a lens or soiling the surface without in the least altering those focal images. The following method, arising out of the discovery that the cornea is the true seat of vision, is preferable. Pro- cure two glass globes somewhat larger than the human eye, fill them with pure water, and place them in a case at about one inch from each other to represent the human eyes. The glasses for examination, whether convex or concave, should now be placed in their frames and held in front of these globes, and before the letter TT pasted on the window. On comparing the magnified or diminished images of the letter on the con-: vex faces of these globes, the practical optician may imme- “diately say whether they are similar in their powers, whether they magnify or diminish equally, and likewise whether the images are clear and distinct. In making this experiment, we should take care to have the globes perfectly similar. Here- after I shall resume this subject, and shall now proceed to the theory of telescopes. As the Galilean telescope is the most ancient, most simple, and most generally used, I shall begin with it. For a good history of this instrument I must refer to an excellent article in Brewster and Rees’s Encyclopedias, and in a concise man- ner shall give the present theory from Mr. Wood’s Elements of Optics, one of the best works I have seen on the subject, and I am informed the one used at Cambridge, perhaps the first mathematical university in Europe. ‘ Galileo’s telescope consists of a convex object-glass, and a concave eye~-glass, whose axes are in the same line, and whose distance is equal to the distance of their focal lengths. A distant object may be seen distinctly through Galileo’s telescope, and the angle which it subtends at the centre of the eye when thus seen, is to the angle which it subtends at the centre of the naked eye as the focal length of the object-glass to the focal length of the eye-glass. . “Let L and E be the centres of the glasses, PQR a distant object towards which the axis of the telescope is directed ; pqr its images in the principal focus of the glass L, and therefore in the principal focus of the glass E. Then since the rays tend to form an image in the principal focus of the concave lens FE, after refraction at that lens they will be proper for vision, or a distinct image of the object PQR Dr. J. Reade on a new Theory of Telescopes. 23 PQR will be formed upon the retina of 2 common eye. Also, the angle under which the object Q P is seen through the telescope is equal to the angle g Ep; and the angle under which it is seen by the naked eye at L is QLP, which is equal tog Lp. Therefore the visual angle in the former case : the visual angle in the latter:: Lg: Eg.” From this reasoning Mr. Wood infers the corollary that the magnifying power of the Galilean telescope is measured by = Before I enter on a mathematical eeanaiiiaions I shall beg leave to call the attention of my readers to what I conceive to be a metaphysical absurdity attending this theory: I shall quote a passage from Dr. Young, an able mathematician and experimental philosopher; who says in his Lectures on Na- tural Philosophy, p. 428, ‘ In the Galilean telescope or opera- glass, a concave eye-glass is placed so near the object-glass that the first image would be formed beyond it and near its principal focus, and the second image formed by the eye-glass, which is the vertical image viewed by the eye, being on the opposite side of the centre, is inverted with respect to the first image, and erect with respect to the object.” And in page 427, he continues, that “in almost all telescopes and com- pound microscopes the image formed by one lens or mirror stands in the place of a new object for another. The opera- tion of such instruments may be illustrated (say Dr. Young and other authors) by placing a screen of fine gauze in the place of the image, which receives enough of light to make the image visible in all directions, and yet transmits enough to form the subsequent image.” Here let us pause, and mark the gross metaphysieal ab- surdity, in supposing that an inverted image painted on the retina could enable the observer to see both an erect object through the telescope, and an inverted object or image at the piece of gauze. Again: Dr. Young supposes that this in- verted image at the gauze transmits enough of rays to form the subsequent image on the retina. Now it is evident this retinal image would be erect in respect to the image on the gauze, 24 Dr. J. Reade on a new Theory of Telescopes. gauze, and therefore the observer should see it inverted: but why see the object erect? I am inclined to hope that Dr. Young will agree with me, not only that this experiment and reasoning involve a metaphysical absurdity, but that they strike at the retinal theory of vision. For to perceive an object both erect and at the same time inverted, by means of one image on the retina, is impossible. But there is no difficulty with respect to the corneal theory of vision; for on holding a concave and convex glass before the eye of an observer looking at the letter on the window, I distinctly per- ceived a small erect image of the letter on the pupil, and like- wise an inverted image produced by the refracted rays as they are called. 2dly, The eye of the observer is always placed close to the eye-glass. If the magnitude of the object seen through the telescope depended on the visual angle g Ep, the object should appear larger the further the eye was re- moved from the eye-glass ; but direct experiment teaches that the contrary is the fact. Indeed, the idea of an inverted image floating in the air, invisible, yet visible, and measured by a visual angle beyond the influence of the nerves, which visual angles are measured by the calf as well as the cow, by the idiot as well as the philosopher, is more than we can believe: even the learned Berkeley, late bishop of Cloyne, who advanced many strange things, could not believe in this. The next object is, that these focal and vertical images, from which our ideas are supposed to be derived, are ten or twenty times as large as the area of the pupil itself, and consequently a con- jurer may as well get into a quart bottle as these images through the pupil. This is a strong objection, and I conceive an in- surmountable one, to the present theory of telescopes. Indeed I am surprised it should have escaped notice. How is it possible that the extreme rays coming from a vertical image one inch or more in length and half an inch in breadth, could not only enter the pupil, but a hole the size of a pin’s head, such as that used by surveyors? We must either admit, what op- ticians do not allow, that rays converge after passing hath ot the concave eye-glass so as to form a very sharp cone at the pupil, and do away with the magnifying power, illustrated by the angle gE p, otherwise the cone would be at the wrong end. Having unscrewed the eye-glass of an opera telescope about three inches long, I held it before the window, and, on placing a card at the principal focus, found that focus to be about five inches from the object-glass. The letter T on the window, being ten feet distant when the eye-glass was again screwed on, the focal image became somewhat enlarged, but very indistinct. What I principally wish to impress rt act, ~t Dr. J. Reade on a new Theory of Tilescopes. 9. Y } fact, the incontrovertible fact, that this focal image when in- tercepted by the card was nearly two inches in bréadth, and yet the pupil through which they were to pass was not 1-4th of an inch, nor the eye-hole of the telescope 1-20th of an inch. And, as already mentioned, if g Ep measured the magnifying power, the further the eye was removed from the eye=glass the larger the object should appear: that the reverse is the fact must be known to every experimenter; indeed at a little di- stance the extreme rays coming from Q and P and crossing at L and then diverging, would not only clear the pupil itself, but the very ears of the spectator ; consequently to argue that we see the object by means of these rays, is absurd. The fourth objection [have to bring forward is, that. focal images are always painted immediately in the axis of the lens, and no where else. ‘Therefore, if these inverted images were the cause of vision, the pupil of the observer’s eye should be always placed in the axis of the lens, and no where else. How~ ever, direct experiment informs us that we can see through a refracting telescope, when the eye is removed considerably to the right or left of the axis. Indeed I have been enabled to see the inverted image of an object painted on the bull’s eye, when my pupil was at right angles with the axis, where it was impossible that any of these rays could enter the eye. Having thus shown, I hope to the satisfaction of my readers, that this mathematical theory of the Galilean telescope is fal- Jacious, I shall now endeavour to substitute a more rational theory, and one founded on direct experiment. I must refer to my former paper on Vision for those experiments which prove that rays diverge in passing through a convex lens, and converge in passing through a concave one. I have also. shown in a former paper that rays never form focal images by crossing, which forms another strong objection. Having pro- cured a convexo-convex lens, whose focus was about two feet, and a concavo-concave lens for an eye-glass, Number 17, I covered half the concave lens or eye-glass with a piece of white paper. I now held these two lenses opposite a lighted candle so as to form a telescope without the tube, and on re- moving the object-glass to the proper distance from the eye- lass, 1 perceived the candle erect and considerably magnified in all its dimensions; and I also perceived an inverted image of the candle, painted on the paper of the eye-glass. Here I again assert, that it would be metaphysically absurd to say that rays coming from this inverted image produced both the sensation of an erect and at the same time of an inverted image. wilt Vol. 63. No. 309. Jan. 1824. D The 26 Dr. J. Reade on a new Theory of Telescopes. The following conclusive experiment will explain the true theory of the Galilean telescope. Having placed a glass globe filled with water ina wine glass resting on a table, imme- diately opposite the letter T on the window, the letter was distinctly painted by refraction on the convex surface. I ncw held the convex object-glass already described at about a foot and half distance over this image, and perceived it to be con- siderably magnified, and surrounded with confused colours. I now interposed the concave eye-glass at about one inch before the image, and perceived the image to be diminished to nearly half its size; but the colours at the margin vanished, and it became, although smaller, much: more distinct and black. This image could be either increased or diminished by approaching or distancing the object-glass. I now pasted a piece of white paper on the globe in the vicinity of the re- flected image, and could perceive that the rays which went to ‘form the inverted virtual image, as it has been named, had 1o- thing to do with the erect image formed on the convex side of the globe by reflection. From this experiment, and nu- merous others, I would infer that in the Galilean tele- scope the eye-glass diminishes the image formed on the pupil by the object-glass; so that a small well-defined image is painted close to the pupil, which standing in place of the object, and magnified by the object- glass to the proper standard of distinct vision, I now made an assistant seat himself opposite this letter on the window; and on holding the glasses in the same manner before his pupil, 1 perceived. si- milar effects; and when the white paper was pasted on half the eye-glass, on his looking at the letter, I perceived the erect image in the pupil, and the inverted image painted on the paper at the eye-glass. I now instead of the white paper put on a piece of white cloth, so as to hinder those rays from going at all to his eye; yet he perceived the object through the telescope. After this experiment, can any person contend that this virtual image is the mean of vision through the telescope ? The field of view in the Galilean telescope depends on the distance of the object-glass, for the size of the image is inversely as the distance. Thus having shown by numerous experiments that these gross refracted rays, with all their twistings and turnings, have nothing to do with the phenomenon of vision either naked or armed with the telescope, further than by throwing a quantity of light into the pupil, I shall now give a figure. a, the letter ‘TT pasted on the window, sends an image to the object-elass BC, where two more images are formed in each 7 Dr. J. Reade on a new Theory of Telescopes. 2 each surface : hence they are sent maghified to the eye-glass DE, which again transmits the image to the eye I’; thence ti: Sle Cc to the retina, and finally to the sensorium. ‘This is a correct outline of the Galilean telescope, supported in every stage by direct experiment. I have particularized Dr. Young’s opi- nions, both because that gentleman is justly celebrated in the scientific world, and because I preferred the living to the dead. The pleasure I feel at having discovered the corneal theory of vision, is somewhat diminished by considering that it strikes at some of the most interesting theories in astro- nomy. For if the theory of refraction be’ proved fallacious, it follows 25 a consequence, that the greatest astronomers have no idea of the distances of the planets, &c., all their calcu- lations being built on visual angles and virtual images. On looking over the Philosophical Transactions for 1821, I find a paper written by a very intelligent experimenter, Mr. J. I’. Herschel, On the Aberrations of Compound Lenses and Ob- Ject-glasses. “This gentleman, -- seemingly unacquainted with the experiments I have published some years ago, both in your Journal and in the Experimental Out!ines,—atfter remarking on Eulerand Dalembert, from whose exertions he says no- thing resulted beyond a mass of complicated formule, he gives a number of algebraic calculations, entirely built on the gratuitous assumption that Newton really separated the whole light into seven coloured rays. Was Mr. Herschel unac- quainted with my experiments? If so, I would beg leave to call his attention to the following. If a square piece of black cloth with a small semicircular piece cut from the lower part in the following manner, be pasted on a pane of glass at the window, on look- L baled ing at it through the lower refracting angle of the prism, we perceive the bottom to be fringed with red and yellow rays; if we now paste another similar piece some little distance below iton the same pane, and in an inverted position, as thus represented we perceive, on looking through the prism, the upper part to be fringed with blue and violet: thus we have three simple and one compound colour produced by these fringes, derived from the black light reflected D2 from 28 Dr. J. Reade on a new T heory of Telescopes. from these two pieces of cloth, and rarefied by sticking on the pane. The violet is evidently compounded of the orange blending with the black light of the lower piece of cloth, and the reader is to notice that when these two pieces are kept asunder, we never perceive more than four colours,—blue, red, yellow and violet: but if we now direct an assistant to approxi- mate the pieces, the yellow fringe of the upper one imme- diately passes over the blue fringe of the lower piece, and forms a vivid green; and until this takes place, no green is ever formed. ‘The rationale of this interesting experiment is too obvious to require much observation, The square piece of black cloth represents the dark window-shutter of Sir Isaac Newton’s experiment; and the two semicircular cuts, when united, represent the circular hole through which the sun- beams passed. The black light reflected from the edges of the hole was rarefied by striking the plane of the prism into colours, and mixing gave the spectrum of seyen colours to the eve. Here we have to remark, that the light passing through the centre of this hole was colourless, not mixing with the fringes, entirely produced by rarefied black light, as is easily shown by passing the shadow of a knitting-needle through a prism placed in the sunbeams. Here we arealso to remark, that the green is formed after emergence by a mixture of the blue and yellow, and by no means a simple colour as Newton supposed. ‘Thus did Sir Isaac Newton compound what he calls seven with the three simple and primary colours,—blue, red, and yellow. Iam fully confident that no unprejudiced person, after repeating this easy experiment, can for one mo- ment doubt that this great philosopher was entirely mistaken in his inference; and however we may admire the ingenuity of that reasoning, which for centuries could make the world believe that transparent light was a compound of opaque rays, yet we cannot extend our approbation to those gentlemen, however learned or respectable, who in the face of direct ex- periment, and [ will venture to say common sense, continue to uphold false principles. If the experiments I have pub-. lished can be refuted, I am ready to give them up and ac-. knowledge myself in error; if not, I call on those gentlemen to act with candour and liberality, I now varied this experiment in the following manner: I allowed the sunbeams to pass through the hole, and placing a prism behind it, so as to pass them through the lower refract- ing angle, I perceived a beautiful oblong spectrum of the hole, not the sun, on the opposite wall: that this spectrum was ob- long and not circular, by no means surprised me, as I had al- ready Dr. J. Reade on a new Theory of Telescopes. 29 ready remarked, that the straight shadow of a knitting-needle became curved by striking end passing through the prism ; consequently a circle would become oblong: but what at first did surprise me was, that the entire colours of the spectrum were reversed from what I saw on looking at the hole through the prism. The violet was now at top, the orange at the bot- tom. ‘This fact escaped the notice of Newton and his fol- lowers: had they noticed it, the theory of repulsion and attrac- tion must have undergone some slight modification. At some future time I shall endeavour to account for this phaznomenon. ‘And I again repeat, that any person performing this experi- ment must be satisfied that the cclours are produced by those fringes, and also that those fringes are produced by the rare- faction of black light, and by no means from any separation of the solar ray. “I shall now say a few words on the astronomical telescope. Mr. Woods has the following description, p. 160 :— * Let L and E be the centres of the two glasses; QP an object towards which the axis of the telescope is directed, and so distant that the rays which flow from any one point in it, and fall upon the object-glass L, may be considered as pa- rallel. ‘Then qp, an inverted image of Q P, will be formed in the principal focus of the glass L, and contained between the lines QLqand PL p; and because LE is equal to the sum of the focal lengths of the two glasses, pq is in the principal focus of the glass AB; consequently pQ may be seen di- stinctly through the glass, if the eye of the observer be able to cojlect parallel rays upon the retina. Produce pL till it meet in the eye-glass in 3, join p IK, and draw BO parallel to pk. Then the rays which flow from p in the object on p its image, enter the eye placed at O in the direction BO; also the rays which flow from Q enter the eye in the direction EO. Thus the angle which QP subtends at the centre of the eye, when viewed through the telescope, is the angle BoE, which is equal to Pig. The angle which QP subtends when viewed with the naked eye from L, is P L Q, which is equal to p Lq.” The same objections I have already brought against the Galilean telescope are equally strong here; I way ore 30 Count Bournon on certain Minerals fore shall merely give a figure of what I conceive to be the true theory of this instrament. a, the letter ‘T: pasted on the window, sends an image to the convex object-glass, which is too much rarefied to pass to the eye, but two inverted images are formed at 6 and ¢, which uniting at the eye-glass CD, form one inverted image d. This again is magnified and sent to the eye at EF, whence it travels to the retina and sensorium. In both telescopes the image at the eye-glass stands in place of an object. As this paper is intended as a mere outline, I have not given the exact foci of the glasses, choosing those of high powers. The experimenter is to distinguish between the con- verging rays and those which form the image. — Let him make the following experiment :—Place the glass globe filled with water in the sunbeams, and holding a convex lens over it, he perceives an image of the lens with the sun painted on the convex surface, and he also perceives the gross refracted rays form an image of the sun which can be thrown to some distance, having nothing whatsoever to do with vision. ‘This I proved by the following experiment: I desired a friend to look at a lighted candle, and holding a convex lens opposite his pupi', I perceived the lens with a magnified image of the candle to be painted on his pupil, while by holding the lens a little obliquely, I threw the refracted rays on the side of his nose or on his forehead. I remain your obedient servant, Cork, April 22, 1823. Joserpu Reape, M.D. VI. Description of certain Gangues of Spinelle brought from the Island of Ceylon by M. Lescurnaurt dE Larour. By M. le Comte de Bournon, Chev. de St. Louis, F.R.S. Se* N a memoir on Corundum which I presented to the Royal Society of London, and which has been printed in the Philosophical Transactions for 1802, after having fulfilled the * Extracted from Observations sur quelques-uns des Minéraux, soit de Ile de Ceylon, soit dela Cote de Coromandel, rapportés par M. Luscux- wauLT pe Laroun, Par M. Le Comte pve Bournon. Paris. 1823. end from Ceylon and the Coast of Coromandel. 31 end which I had proposed to myself, which was to make this substance more perfectly known than it then was, by deter- mining at the same time its intimate connexion with all the stones to which jewellers apply the term oriental, such as the oriental ruby, topaz, amethyst, sapphire, &c., I took advan- tage of this circumstance to insert some details relating to other substances, and more particularly to spinelle. Mr. White, an officer in the English army, whom, on his departure for Cey- lon, I strongly recommended to procure some stones from that island, sent us, in a collection otherwise of little value, two fragments of rocks, in which I observed, for the first time, the spinelle of Ceylon in its gangue, and not from the sand of the rivers of that island. It is twenty years since this observation was made; and since that period we have received no addition to our first knowledge upon this subject respecting the corundum of nearly the whole of India, and that, more interesting on ac- count of its transparency and purity, of the island of Ceylon. Notwithstanding that the English, masters of nearly the whole of India, and at present of the whole of Ceylon, carry on a regular correspondence between every part of India and the metropolis of their country, they are still, I think, liable to reproach in this respect; which opinion arises from the in- terest which I take in science, and in its progress in a country where it has procured me so many gratifications*. M. Leschenault de Latour, sent into India by the French Government, with a particular commission to procure for our colonies the vegetables which appear to be yseful to their agriculture, as well as to the extension of their commerce, is the inquirer to whom we are indebted for the most extended knowledge of the mineralogy and geology of some of the most interesting districts of India; on account of the information which he has collected concerning these two sciences, though he * This reproach, perhaps, may seem severe, the Geological Society of London, of which I had the honour to be one of the founders, haying printed in 1821, in the second part of the fifth volume of its Transactions, a letter addressed from Ceylon by Dr. John Davy to Sir James MacGregor, and which was read to the Society on the 4th of December 1818. But the details contained in that letter, relating as much to the mineralogy as to the geology of Ceylon, can only be considered, it appears to me, as those of a slight glance thrown over the island. The indications and descriptions which accompany the substances therein named, are so short and incom- plete, that they seem but to convey a promise, specdily to be fulfilled, of a work of more importance, containing more instructive details, and so ar- ranged as to arrest the attention of the mineralogist and geologist. I can- not help expressing my regret, that Dr. Davy, so well qualified for this un- dertaking, has not carried this work to perfection, Perhaps, howeyer, my regret is premature, s was $2 Count Bournon on certain Minerals brought was at the time almost a stranger to them. M. Leschenaulty remarkable for his extensive knowledge in different hranches of natural history, and especially for his zeal and activity, which are equalled only by his great modesty, during a stay of six years in India, scarcely seven months of which were de- voted to the researches which he made in the island of Cey- lon*, has enriched the French colonies, and principally the Jardin Royal of the Isle of Bourbon, with a great number of plants, useful to the agriculture of the island, as well as to the amelioration, in this respect, of its commercial relations. After having enriched the Jardin du Roi at Paris with many plants, birds, quadrupeds, insects, fishes, and crustacea, which fur- nish several new species, he has returned to his own country; bringing with him an extremely interesting collection of mi« nerals and rocks, which he collected in the different parts of India through which he travelled. After having first subs mitted this collection to the choice of the professors of the Jardin du Roi, M. Leschenault presented to the private mi- neralogical collection of the King, the specimens which were subjected to a second choice made by me. Though I had to regret the loss of a great number of minerals, of which he had no duplicates, this second choice has neverthe= less been very useful to the collection, by the facts which their study has put me in possession of. ‘These facts enable me to add some new details to those which I formerly gave relat- ing to corundum and to spinelle; they likewise enable me to make known some others, which the different mineral sub- stances, brought home by this traveller, have. introduced to our notice. I shall commence these details with the description of the various gangues of the spinelle of the island of Ceylon, which are among the minerals presented to the private collection of the King by M. Leschenault. The first gangueis a carbonate of lime and magnesia, or, more simply, a dolomite. It is colourless, and composed of distinct parts crossing each other in different directions. It contains, thinly disseminated, some small crystals of phosphate of lime of a deep beryl blue, sometimes placed between the particles of dolomite, but more frequently contained in its sub- stance, and which are only discovered by the fractures made to determine the characters of the mineral. These crystals are. * M. Leschenault arrived at Ceylon at the end of July 1820, and quitted it in February 1821, after having been obliged to return to Columbo by a: dysentery; and in the short time of his residence in the interior, the science of botany, the special object of his mission and researches, was in conse- quence that to which his chiefattention was directed, : generally from Ceylon and the Coast of Coromandel. 33 generally of a rounded and indeterminate form; nevertheless, on one of the specimens in the King’s collection 1 observed among them a complete l:exahedral prism, and another with many small facets on the edges of its terminal planes. These crystals are but few in this gangue, which likewise contains, in still smaller quantity, some small crystals of spinelle of a pale-red or flesh-colour. ‘They are even’ contained in the substance of the dolomite; their form is either a regular octa- hedron, a cuneiform octahedron, or an octahedron the edges of which are replaced by a plane. The dolomite of this gangue dissolves in nitric acid, without any sensible effervescence, and with extreme slowness: a small fragment requires forty- eight hours for its complete solution. It was found by M Leschenault very near Candy. It is likewise found, as well as the two following gangues, in the isolated rocks at the feet of the elevated mountains which separate Candy from Co- lumbo, and upon the road which joins those two towns. The second gangue is likewise dolomite, in a lamellary state, and formed, in the same manner as the preceding, of particular masses, but smaller and crossing each other in dif- ferent directions. When first placed in nitric acid, it pro- duces a very lively effervescence, which becomes weaker by degrees, and at last very feeble. In a short time after it has been placed in the acid, it becomes disintegrated into an infinity of small particles, the greater number of which con- tinue to dissolve very quickly. The analysis which has been made of it gives more carbonate of lime than is neces- sary to the composition of dolomite. I strongly suspect this rock to contain some particles of carbonate of lime interposed in its substance; from which would arise the lively effect of the acid upon coming into contact with it, its quick solur tion, as well as the disintegration which it undergoes. This second gangue contains, in rather greater proportion than the preceding, some flesh-coloured crystals of spmelle. It also contains some very small crystals of mica of a very deep yellow colour. Here and there likewise may be observed some small crystals of pyrites, of the icosahedral variety; but I have not observed any trace of phosphate of lime. This gangue was found by M. Leschenault seven leagues east from Candy. Although the third gangue of spinelle is from the same district as the former, it is essentially different, and of a very particular nature. It consists of very coarse grains, the tex- ture of each of which is lamellated. Of these grains a very great number are white, and their fracture has a very brilliant Vol. 63. No. 309. Jan. 1824. E lustre ; 34 Count Bournon on certain Minerals brought lustre; they belong to the dolomite. The others have a gray tint, and their fracture is less bright; they belong to car- bonate of lime; but they are mingled with interposed particles of dolomite. In this gangue are disseminated some small icosahedrons of pyrites, some crystals of mica, of an orange yellow; some amorphous particles, and also some regular crystals of apatite, resembling in their green colour the variety called spargel- stein of Spain. It likewise contains a still greater quantity of this substance in small flattened hexahedral prisms, very diffi- cult to recognise on account of a thin white layer which en- tirely covers them; but when this is removed, the green colour of the apatite appears. I am ignorant whether this white layer arises from an alteration of the apatite, or’ whether it belongs to another substance which would be completely insoluble in acids; for it was in dissolving this rock in nitric acid that I obtained these crystals. This gangue contains, besides, many minute particles of magnetic pyrites, and likewise a considerable quantity of small crystals of spinelle, of a fine rose colour. I observed among the latter some complete octahedrons, some with the edges replaced, and some, each of the solid angles of which was replaced by four planes, placed upon the faces, as frequently seen in the pleonaste spinelle of Mount Somma, and which I have also observed in the red spinelles found in the sand of the Ceylon rivers. Some of the yellow crystals of mica have a brilliant lustre, on which account they might be very easily taken for some of the hard stones called: gems. The memoir on Corundum, which I presented to the Royal Society of London, having been printed in the Journal des Mines for 1803, by referring to pages 97 and 98 of the Num- ber for May of that Journal, it will be seen that this gangue is absolutely of the same nature as those sent to London, from the island of Ceylon, in 1801 or 1802, for the first and the last time*. The fourth gangue of spinelle is extremely interesting: it is composed for the most part of spinelle and of mica. The spi- nelle is in octahedral crystals of a brown colour approaching to violet, and they are much larger than those contained in the gangues above described. The colour of some of them is so deep, that they appear to be black; they form one of the varieties of the pleonaste spinelle of Ceylon. These crystals, which are extremely abundant in this gangue, are very close to each other, and often form considerable masses, in which * See also Phil. Trans, for 1802, p. 308-311.—Eoir. come Jrom Ceylon and the Coast of Coromandel. 35 some of them are in contact with others, and even penetrate them. The mica is of a brown yellow colour, slightly orange by refracted light; it forms, in this gangue, considerable masses, to which we may give the name of “ mica en masse lamellaire.” The detached parts of these masses are perfectly transparent, and have avery brilliant lustre. By means of nitric acid I have extricated one of them, of the dimensions of two inches by one inch and three lines, from the carbonate of lime, which con- stitutes a part of the gangue; this mass is perfectly pure, with the exception of some insoluble particles which it contains ; among which are particles of magnetic pyrites. I have never yet seen mica in such considerable masses presenting so beautiful and brilliant an aspect. The mica, which in this specimen is very pure, has sufficient solidity to resist pressure, and is con- sequently very suitable for the illustration of what I asserted for the first time in 1813, in the summary catalogue of my collection, now become that of the King, that the integrant particles of mica are of themselves of very great hardness, and that this substance is so easily broken on account of the weak- ness of the cohesive force which unites these particles to each other; but that, when small fragments or crystals of mica have sufficient thickness to resist pressure, they cut glass with facility, and will even scratch quartz, or at least deprive it of its polish, a fact which is further confirmed by the nature of its refraction, as well as by that of its reflective power*. The King’s private collection possesses a suite of specimens of mica for study, which presents this extremely interesting substance under a great variety of aspects very little known. This suite, which in my opinion is unique, should be consulted in order to obtain a complete knowledge of this substance. The fifth gangue is very particular; it is a girasol, mixed with particles of a slightly grayish white, with some of a yel- lowish green, and with others in the state of girasol jasper, on account of the hydrate of iron which is interposed in them. The specimen placed in the Royal collection has adhering to it a small piece in an earthy state, mixed with much brown * All these characters induce me to believe that this fourth gangue of Ceylon spinelle is the same as that, which, according to Dr. Davy, forms hills in the vicinity of Candy, and in which he likewise observed ery- stals of ceylanite, which he seems to consider as a different substance from spinelle. Iam ignorant of his reasons for making this distinction: cey- lanite, it is true, contains a large proportion of iron, but the quantity of that metal varies in the different analyses which have been made of spinelle; I think, therefore, that it is merely interposed in the ceylanite. E2 mica, 36 Mr.8. Seaward’s Description of an improved Gauge mica, of which there are some small plates interposed, even in the substance of the girasol. This gangue contains, in the interior of its substance, a considerable quantity of pale-blue crystallized spinelle, among which, however, there are some crystals of so deep a blue that they appear black. M. Les- chenault only found this rock on the bank ofa river seven miles to the north-east of Candy, on the route to the province of Fassagram, where he met with it in isolated masses. The sixth gangue of Ceylon spinelle, which is still more particular, is a rock of a granitic aspect, in which the mica is replaced by molybdena in small thin lamine. This rock is principally composed of transparent granular felspar, and of these laminze of molybdena. One may observe, besides, some little plates of brown mica, which are thinly dissemi- nated, and a great number of very pale-red crystals of spinelle. This rock was found by M. Leschenault, seven miles to the north-east of Candy, in the same district as the preceding, and likewise in isolated masses upon the bank of the same river. I may add to the description of these gangues of spinelle, that of a seventh, which is the second of those I have de- scribed in the paper on Corundum, printed in the Philosophical Transactions for 1802. This gangue consists principally of transparent felspar or adularia, pure in one part, and mixed in the other with magnetic pyrites and a little carbonate of lime. Some small crystals of spinelle are disseminated in it, but more thinly than in the other gangue mentioned in the same memoir. VII. Description of an improved Gauge for ascertaining with Precision the Pressure of highly compressed Steam, Gases, and Fluid Bodies. By Mr. Samur. SEawanp. To the Editors of the Philosophical Magazine and Journal, Gentlemen, KERMIT me to offer you the accompanying description of __a gauge for measuring the pressure of highly compressed fluids or gases, which I shall feel gratified by your introducing into. your valuable Magazine, if you consider it deserving of that distinction. I am, gentlemen, yours, &c. 3 Charles Street, City Road, SAMUEL SEAWARD, Jan. 14, 1824, Descrip- for the Pressure of highly compressed Steam, Gases, §c. 37 Description, &c. Considerable difficulty has been experi- enced in acertaining in a satisfactory man- ner the exact pressure of highly condensed gases or fluids. : 4 The usual method of accomplishing this object is by the rising of a column of mer- cury ina glass tube hermetically sealed at the top; the tube being previously filled with air at the ordinary pressure of the at- mosphere. For as the mercury rises by the pressure of the gas, the air confined in the tube above the surface of the mercury will be compressed to the same degree as the gas itself, making proper allowance for the weight of the column of mercury. But it happens that when fluids are required to be com- pressed to 30 or 40 atmospheres, it becomes necessary to have the tube of the mercury gauge of very great length, say from 30 to 4.5 feet, otherwise the divisions of the upper part of the scale will be much too small for useful reference; but this great length ren- ders the apparatus exceedingly inconvenient for practical purposes. The accompanying drawing represents a gauge on an improved principle, which it is expected will be found much more conveni- ent and correct than the gauge in common use. The gauge consists of two small cylin- drical chambers A and B, and the glass tube C. The communication between the two is by the small tube d, which reaches nearly to the bottom of the lower chamber. The glass tube C we will suppose to be about eight feet long: the chamber B is to be filled with mercury as high as the line cc; the tube e is to admit the compressed gas or fluid, which acting on the surface of the mercury forces it up the tube d, which after filling the chamber A will rise in the tube C. Now, supposing. the apparatus to be pre- viously filled with air of the common atno- spheric pressure, and that the chamber A be equal to 19 times the capacity of the tube ‘aunssorg sosoydsowy 38 Mr. S. Seaward’s Description of an improved Gauge tube c; it is quite plain, that when the mercury is forced by the pressure of the gas or fluid into the chamber A, and rises up to the bottom of the glass tube, the air in the tube C must then be compressed 20 times, and will consequently indicate & pressure of 20 atmospheres; and if the mercury is then raised half way up the tube C, the air will then be compressed 40 times, and will indicate a pressure of 40 atmospheres. We have considered that the glass tube C should be eight feet long; but if, instead of eight feet, we make this tube onl four feet long, and fix to the top a small hollow ball D, of equal capacity with four feet of the tube; then if the mercury rise four feet high in the tube, or up to the ball, the apparatus will still indicate a pressure of 40 atmospheres, as if the tube eight feet long had been employed. By this means we have a compact instrument, which will indicate in a satisfactory manner the various pressures within the range of 20 and 40 atmospheres ; for the divisions on the scale for the whole of this range will be as large as if a tube of the common form 70 feet long had been employed. But it may be objected that this instrument is imperfeet, because it will not indicate any lower pressure than 20 atmo- spheres, nor any higher than 40. To this it should be ob- served, that in all. practical applications of a gauge of this sort, as the compression of gases, &c., it is only within certain limits that it is desirable to ascertain the exact pressure: for instance, in the case alluded to, it is of no consequence to ascertain the pressure when below 20 atmospheres ; nor is it ever required to be elevated above 32 atmospheres; therefore a range, as here proposed, of from 20 to 40 atmospheres is quite sufficient for practical purposes in working the appa- ratus ofa portable gas establishment, &c. Perhaps it is unneces- sary to observe, that the various ranges may be altered at pleasure, from the lowest pressure up to the greatest; for by properly arranging the different sizes of the ball D and cham- ber A, it may be made to indicate from 1 to 20—from 20 to 40—from 40 to 60, and 60 to 100 atmospheres. And if it should ever happen to be necessary to ascertain the exact pressure of the fluids from 1 atmosphere to 100, which is a thing perhaps never wanted, it can still be done with the same degree of exactness throughout; for, by using two or more of these gauges graduated for different ranges, we thus obtain a correct.scale of reference, which it would be impos- sible to do in the old method; say from 1 to 15—15 to 45— and 45 to 100. It is here proper to observe, that the weight of the column of mercury in the chamber A, and in the tube C, should be : ; taken _ for the Pressure of highly compressed Steam, Gases, $c. 39 taken into account as well as the pressure of the air in the tube C; otherwise it will not be a correct indication of the force of the gas or fluids acting upon the surface of the mer- cury in the chamber B. Therefor e, in the following calcula- tion for graduating the scale attached to the tube ,; a proper allowance is made for the weight of the column of mercury. Annexed is the investigation of a theorem for graduating the scale. The table was computed therefrom, anda scale agreeable thereto is made to be attached to an instrument which I am now making, for the purpose I have described. Calculation for the Scale. Ascertain nicely the capacity of the chamber A, together with the tube C and its ball D, and let that quantity be de- noted by M. ‘Then ascertain the capacity of the tube and ball only, and denote that by m: and let the ratio of these two quantities be denoted by 7; that is r= eS And let a denote, in inches, the whole length of the tube C, including a length of tube equal in capacity to the ball D; and let 2x represent the height, in inches, of the mercury in, the tube C, from the bottom. of the tube at a. Then when the mercury just reaches the bottom of the tube at a, it is plain that the pressure must be equal to r atmospheres. And when the height of the mercury in the tube is equal z, then the pressure on the inclosed air will be equal — xr at- mospheres. But in order to ascertain exactly the force of the gas acting ; upon the surface of the mercury in the chamber B, we must add to the above the weight of the column of mercury above the level in the said chamber B. Let 4 denote the number of inches that a, the bottom of the tube, is above the level of the mercury; and let c represent the height of a column of mer- cury equal in weight to one atmosphere, say 29°5 inches. Then the weight of the column of mercury in the tube C will r+b be re . Therefore putting y¥ equal the required number of atmospheres, we shall have r+b xr + sy «On, _ 27 actin avr alk +car + ab—acy. (No.2) Now put 7 the ratio=20° and a=76°8, the whole length of the tube including the ball at top; and put c = 29°5 = the height 40 Mr. A. H. Haworth on some new Cacti and Mammillarie. height of a column of mercury that will balance the pressure of the atmosphere; and put b=7°3. Thus, if these values be substituted in the equation No. 2, and different values taken for y, we shall thereby obtain the corresponding values of 2, or the height of the column of mercury in the tube C, indi- cating the several pressures. Thus, put y=30 atmospheres ; then L=477°25 — V/ 2277675 +45312 + 560°64— 67968 v=23°74 inches. That is, the altitude of the mercury in the tube will be 23-74. inches, when the pressure is equal to 30 atmospheres pressing upon the surface of the mercury in the lower chamber B. And in this manner have been computed the different values of z, corresponding to different pressures, as shown in the following table: Table for graduating the Scale. Values of «x Values of w Pressure. or height of Pressure. or height of the mercury. the mercury. 21 atmospheres 2°49 inches. 31 atmospheres 25:42 inches. 22 ditto 5°57 32 ditto 26°99 23 ditto 8°43 33 ditto 28°48 24 ditto 11°10 534 ditto 29°89 25 ditto; 5:13:57 35 ditto 31:21 26 ditto 15°88 36 ditto 32°48 27 ditto 18°04 37 ditto 33°67 28 ditto 20°07 38 ditto 34°80 29 ditto 21:96 39 ditto 35°88 30 ditto ~~ 23°74 40 ditto 36°91 VIII. Descriptions of some new Cacti and Mammillarie, re- cently brought from Mexico by Mr. ButuocK of the Egyp- tian Hall, Piccadilly ; and now preserved, with many other very rare Plants, in the Nursery of Mr.'Tatr, in Sloane- street. By A.H. Haworth, Esq. F.L.S. &c. To the Editors of the Philosophical Magazine and Journal. Gentlemen, ALLow me to transmit to you herewith technical descrip- tions of some new and very remarkable plants of the family of Cacti Juss., which I hope you will admit into an early Number of your valuable Miscellany. And I remain Your most obedient servant, ~ @ueen’s Elm, Chelsea, Nov. 1823. A. H. Haworrtu. Cacti Mr. A. H. Haworth on some new Species of Cactus. 41 Cactus. Linn. aliorumque. senilis. C. oblongus; subviginti-angularis; spinarum radiis Ve capilliformibus elongatis. Obs. Unam plantam semipedalem solum vidi, an- gulis profundis viridibus. Spinarum radii inter se dense flexuosi sive intertexti depresso-recurvuli; in singulo fasciculo circiter 12, omnino capillacei 4-un- ciales plantamque tegentes praesingulares; uti comam albicantem in capite senili. Nullo, mihi noto, affinis, at forte cum Cacto multangulari Willd. sectionem proprien formavit. Flores non vidi, neque in sequen- tibus. latispinus. C. depresso-spheroideus; sub 21-angularis; spi- 2. narum radiis variantibus, una infimo deflexo latissimo plano. Obs. Cacto recurvo Milleri proculdubio proximus, at angulis numerosioribus, et spina lata, non erecta nisi in juventute. WValde depressus, angulis porcisve validissimis duris viridibus. Spinarwm radii variantes sordide Jutei, circiter 12 exterioribus in singulo fas- ciculo ordinariis, subuncialibus, circiter 4-6 aliis 10-20-plo majoribus, subduplo longioribus (horum ultimorum), sub 3 superioribus subulatis sordidé pal- lescentibus, elevatim densé annulatis fere ad apicem levem, demum rufam, annulis (in lente) rufescentibus, 2-3 infimis spinis (in singulo fasciculo) plus minus planatis, ipsa infima (spina) omnino plana deflexo- incurvula 3 lineas lata apice recurvo subulato. Obs. Spinze omnium validissimze primo _fulvo- rufescentes, demum superne rufee, denique sordide. Mammitiarta. Nob. in Synops. Pl. Succulent.— Aliorum Cactus. magnimamma. M, mammis magnis perviridibus apice tomen- 3. tosis, spinis subquatuor validis expansis, 2-3 recurvis lutosis apice nigris. Obs. Plantam unam bifidé germinatam subglobo- sam pugno minorem solum vidi. ‘Tomentum ad basin spinarum breve ac densum est. lanifera. M. simplex tereti-obovata, mammis apice lanosis 4, plus 20-spinosis, spinis radianter patentibus variis. Obs. Spinze exteriores in singulo fasciculo minores albee (mortuis nigris) subsex interiores 3—5-plo lon- giores quam ultimis et 3-7-plo validiores, fulvo- fuscescentes, superné nigra seu nigricantes. Plantam $—4-uncialem solum vidi. Vol. 63. No. 309, Jan, 1824. F geminispina. 42 Dr. Burnett's Account of the Effect of Mercurial Vapours geminispina. M. columnaris; mammis exiguis numerosissimis, 5, spinis parvis intertextis albis; duabus in singulo fas- ciculo czeteris multoties longioribus. Obs. Plante plus quam semipedales fere omnino sim- plices teretes, superne sensim crassiores apice vix con- vexo. Mamme pallide virides spinis recurvo-radianti- bus capillaceis albis; duabus in singulo fasciculo validi- oribus geminatim semierectis pungentibus apice nigris. Obs. Spinarum fasciculi radiantes et inter se con- fertim patentes, fere totam plantam eleganter tegentes. IX. An Account of the Effect of Mercurial Vapours on the Crew of His Majesty's Ship Triumph in the Year 1810. By WitiaM Burnett, M.D., one of the Medical Commissioners of the Navy, formerly Physician and Inspector of Hospitals to the Mediterranean Fleet. Communicated by MaTtHew Bai.uiE, M.D. F.R.S.* [* has long been known, that in the vacuum of the barome- ter, mercury rises in a vaporous state at the usual tem- perature of this climate, and that persons employed in the mines from whence this metal is procured, as well as those who are employed in gilding and plating, have suffered para- lytic and other constitutional affections, from inhaling the air saturated with mercurial vapours: had any doubt remained of mercury existing in the state alluded to, it would be effectually removed. by the experiments made by Mr. Faraday, detailed in the twentieth number of the Journal of Science, &c. An unprecedented event, which occurred in one of His Majesty’s ships of the line, at Cadiz, in the year 1810, a short time before I took upon me the charge of the Medical De- partment of the Mediterranean Fleet, has afforded me an op- portunity of illustrating this subject on a very extensive scale, the details of which may not, perhaps, be uninteresting to the Royal Society. The Triumph, of 74 guns, arrived in the harbour of Cadiz in the month of February 1810; and in the following March a Spanish vessel, laden with quicksilver for the mines m South America, having been driven on shore in a gale of wind and wrecked under the batteries, then in possession of the French, the boats of this ship were sent to her assistance, by which means, during many successive nights, about one hundred and thirty tons of the quicksilver were saved and carried on * From the Philosophical Transactions for 1823, Part II. board on the Crew of His Mayesty’s Ship Triumph. 43 board the Triumph, where the boxes containing it were prin- cipally stowed in the bread-room. The mercury, it appears, was first confined, in bladders, the bladders in small barrels, and the barrels in boxes. The heat of the weather was at this time considerable, and the bladders, having been wetted in the removal from the wreck, soon rotted, and the mercury, to the amount of seyeral tons, was speedily diffused through the ship, mixing with the bread, and more or less with the other provisions. ‘The effect of this accident was soon seen, by a great number of the ship’s crew, as well as several of the officers, being severely affected with ptyalism, the surgeon and purser being amongst the first and most severelly affected, by the mercury’s flowing constantly into their cabins from the bread-room; their cabins being, as is usual, on the orlop deck, separated from this store by partitions of wood. In the space of three weeks from the mercury’s being received on board, two hundred men were afflicted with ptyalism, ulcerations of the mouth, partial paralysis in many instances, and bowel complaints. ‘These men were removed into transports, where those more slightly affected soon got well; but fresh cases occurring daily, Rear-Admiral Pick- more, then in command of the squadron, ordered an inspec- tion to be made by the surgeons thereof, and, in consequence of their report, sent the Triumph to Gibraltar to remove the provisions, and purify the ship by ablution, the affected men being sent to the Naval Hospital; which order was strictly attended to; the provisions, stores, and likewise the shingle ballast, being removed on shore. Notwithstanding the removal of the provisions, &c., and afterwards frequent ablution, on restowing the hold, every man so employed, as well as those in the steward’s room, were attacked with ptyalism; and during the ship’s passage, and on her return to Cadiz, the fresh attacks were daily and numerous till the 13th of June, when the Triumph sailed for England. Afier their departure from Cadiz they experienced fresh breezes from the N.E.; and the men being kept constantly on deck, the ship aired night and day by windsails, the lower- deck ports allowed to remain open at all times, when it could be done with safety, allowing no one to sleep on the orlop deck, and none affected with ptyalism on the lower deck, a very sensible decrease in the number daily attacked soon be- came apparent; but, nevertheless, many of those already af- fected became worse, and they were under the necessity of removing twenty seamen and the same number of marines, with two serjeants and two corporals, to a sloop of war and ¥ 2 the 44 Dr. Burnett's Account of the Effect of Mercurial Vapours the transports in company. On their arrival in Cawsand Bay, near Plymouth, on the 5th of July, not one remained on the list for ptyalism. The eflects of the mercurial atmosphere were not confined to the officers and ship’s company; almost all the stock, con- sisting of sheep, pigs, goats, and poultry, died from it; mice, cats, a dog, and even a canary bird, shared the same fate, though the food of the latter was kept in a bottle closely corked up. The surgeon (Mr. Plowman) informed me, in conversation, that hz had seen mice come into the ward-room, leap up to some height, and fall dead on the deck. The Triumph, previous to this event, had suffered consi- derably, by having a number of her men attacked with malig- nant ulcer, which at one time prevailed to a considerable ex- tent in our ships, both at home and abroad; and in many of the men who had so suffered, the ulcers, which had long been completely healed, without even an erasure of the skin, broke out again, and soon put on a gangrenous appearance. The vapour was very deleterious to those having any ten- dency to pulmonic affections ; three men died of phthisis pul- monalis, who had never complained, or been in the list before they were saturated with the mercury; and one man who had suffered from pneumonia, but was perfectly cured, and an- other who had not had any pulmonic complaint before, were left behind at Gibraltar, labouring under confirmed phthisis. Two only out of so large a number affected died from ptyalism, Sekar having taken place in their cheeks and tongue: they ad previously lost all their teeth. In the case of a woman, who was confined to bed in the cockpit with a fractured limb, not only were all the teeth lost, but many exfoliations also took place from the upper and lower jaws. The mercury showed its effects upon the ship herself, by the decks being covered with a black powder; but quicksilver was not discovered at any time in this powder in a native or globular state, though the brass cocks of the boilers, and the copper bolts of the ship, were covered with the metal, the last to some extent within the wood; a gold watch, gold and silver money kept in a drawer, and likewise some of the iron-work of the ship which had been kept bright, evidently showed the influence of the prevailing atmosphere, being in some places covered with quicksilver. In a communication with which Mr. Plowman, surgeon of the Triumph, has obliged me, he states, that those who messed and slept on the orlop and lower decks, with the exception of the midshipmen, suffered equally, while those on the main or ; upper on the Crew of His Majesty's Ship Triumph. 45 upper deck were not so severely affected: the men who lived and slept under the forecastle escaped with a slight affection of the gums. The only reasons which can be assigned for the partial escape of the midshipmen, are, that the windsails were kept always in action, and that these gentlemen were almost constantly on deck, or were more frequently employed on ser- vice out of the ship, in proportion to their numbers, than the men. 7 Various opinions were entertained of the manner in which the systems of the sufferers were brought under the influence of the mercury. By some, it was supposed to have originated from the use of the bread and other provisions, with which the mercury had mixed itself: and to such an extent was this opinion carried, that I find, by reference to official documents in the Victualling Office, seven thousand nine hundred and forty pounds of biscuit were condemned as unserviceable from having quicksilver mixed with it. By others, amongst whom was Mr. Plowman, the surgeon, it was considered to have arisen from inhaling the mercurial!- ized atmosphere; and from the preceding details, I think there cannot remain a doubt that this opinion was the true one. It is well known that mercury, in its native state, has often been administered in very large doses, in.cases of obstinate constipation, without producing any specific efiect on the system, merely removing the affection by its specific gravity. I have, however, reason to believe, from the accounts of Orfila, and others, that if the mercury was to be retained in the intestines for some time, and thus subjected to the action of the contents of the stomach and bowels, a part might be- come oxidated, and being conveyed into the system by means of the absorbents, would there show its specific effects. But after the removal of the provisions, &c. at Gibraltar, many fresh cases occurred, and many relapses amongst those who had_ been cured out of the ship, took place on their re- turn to duty on board, which effectually destroys the proba- bility of this having been the cause of the succeeding ptyalism, and other morbid affections. It only remains for me to offer my opinion, of the manner in which the system became saturated by the mercury; and this I conceive to have been effected by inhaling the mercurial vapours; the quicksilver being then in the most perfect state of division, was readily taken up by the absorbents of the lungs, and soon showed its influence on the system generally. This idea is very much strengthened by the effect which was produced 46 MM. Monticelli axd Covelli on the late produced on the animals on board, already mentioned, as well as by the circumstance of a great number of men being at- tacked after the ship was cleared at Gibraltar, and till she arrived in a more northern latitude. It may be considered out of place here, to give any detail of the curative means employed. I shall therefore only briefly state that sulphur given in large quantities internally, pro- duced no alleviation of the symptoms; on the contrary, it greatly augmented the bowel complaints, with which many of the men were affected, and brought on a most severe te- nesmus; consequently, it was laid aside; applied externally, it was of no use. The only plan which produced effectual relief was removal from the ship, with the frequent use of small doses of neutral salts and detergent gargles. W. Burnerr. X. Account of a Work entitled “ Storia de’ Fenomeni del Vesuvio avvenuti negli anni 1821, 1822, e parte del 1823,” etc. ‘ History of the Phenomena of Vesuvius during the Years 1821, 1822, and Part of 1823 ; accompanied ‘with Observations and Experiments. By J. Monvicets1, Per- petual Secretary of the Royal Academy of Sciences of Naples ; and N. Covet, of the Royal Institute of Encouragement.” By M. Menarp bE La Groye*. qe general form of this work is nearly that of a journal, that is to say, the facts are recited in the natural and suc- cessive order in which they were collected. If we judge of the ultimate celebrity of M. Monticelli, by that which he has for several years enjoyed, arising from his former labours, we shall be induced to believe that he will occupy the first rank among the historians of this celebrated volcano, which we al- ways consider as in some sort a volcanic archelype. The new work which we announce was preceded by a description of the eruptions of 1812 and 1817. The same author likewise published in French, in conjunction with M. Covelli, some “ Observations and Experiments made at Vesuvius during Part of the Years 1821 and 1822.”—(See Bulletin, tom. ii. p. 435.) The first section of the work which now occupies our attention, is for the most part a repetition, * From the Bulletin des Annonces Scientifiques, tom. iv. p. 34. M. de la Groye’s analysis of the former work by MM. Monticelli and Covelli above alluded to by him, will be found in vol. Ixii. of the Philosophical Magazine, p. 90. in Phenomena of Veswoius. 47 in Italian, of that just mentioned. ‘The new eruption in the month of October last, not only one of the most considerable which have occurred since that so celebrated in 1794, but even of the grandest which have ever been witnessed, having presented to the authors an extensive field for new experi- ments and observations, induced them to resume and enlarge that work by the addition of two sections, a preface, a table of contents, ard figures. The most remarkable of the principal facts contained in this work, are enumerated by the authors themselves in the pre- face. These are the formation of earthy pisolites among the pulverulent lava; the particular and cblique ejection of a fine sand, or, as it is vularly named, volcanic ashes, which also produces small and extremely singular currents, having at a distance the appearance of streams of hot water; that of other currents formed entirely of substances much more bulky, but equally incoherent; the examination made with new and peculiar interest of the discontinuance or intermission, and of the par- tial fits of the eruptions, which are compared by the authors to the paroxysms of violent diseases; the positive observation of sulphurous acid, and of sulphur itself, in the lava which has ceased flowing; that of carbonic acid in fumeroles of lava, before it is completely cold, and especially of a considerable evolution of this acid, after great eruptions, giving place to large and numerous mofettes which are manifested around the base of the mountain. This fact is so remakable and of such importance, that the celebrated Sir Humphry Davy thought that it might lead to the discovery of the origin of the various calcareous rocks in which volcanic substances are contained, either in cavities or in the substance of the rocks them- selves. Among the newly recognised productions of Vesuvius, will be remarked the sulphates and chlorides of manganese, which characterize a number of saline metallic sublimates, and the existence of which in the mineral kingdom has been hitherto unknown. This work likewise offers several considerations con- cerning the diversity of temperature, which the different volcanic vapours require in order to their attaining a solid state. The veracity of Pliny the younger, in the description he gives of the eruption which occasioned his uncle’s death, has been fre- quently questioned; but MM. Monticelli and Covelli prove, by comparing several passages of his relation with the effects which they have themselves observed, that he is entitled to complete confidence. They have also observed the formation of the last cone, and seen it gradually disappear in part, in the same manner as that which, according to the description of Strabo, existed 48 MM. Monticelli and Covelli on the late existed before the horrible catastrophe of the year 79. The first section is entitled “* The State of Vesuvius trom the Eruption of 1820 and 1821 to the Commencement of October 1822; with Observations and Experiments.” It contains an article on the state of the volcano from the 11th of May 1822 to the beginning of October, not inserted in the work which pre- ceded it; from which it also differs in some other respects towards the end. The second section is a ‘ Journal of the Eruption of October 1822.” The authors first speak of the state of the atmosphere during the spring, summer, and autumn which preceded that eruption; a state rendered more remarkable by the excessive drought which prevailed. ‘They mention some movements of the volcano precursory to the eruption; and then proceed to the description of the pheeno- mena observed in the interval between the 21st of October and the 11th of November; during which time occurred the va- rious paroxysms of that eruption. The zigzag lightning began to appear on the 22d, at two o’ciock in the afternoon, not proceeding from the pine of ashes, or from the great cloud of smoke arising from it, but in a part of the atmosphere be- tween both and occupied only by the ashes. The lightning was not accompanied with any detonation. This electric phz- nomenon, which increased as the violence of the eruption di- minished, did not take place in the middle of a paroxysm, but at the edges of the clouds of ashes. At a later period the lightning was seen to emanate not only from the dusky clouds or the air, but also from the earth, and even to traverse the roads. Our authors discovered, by very simple but decisive expe- riments, that the falling cinders were strongly and vitreously electrified. Electric discharges were still seen from the sum- mit of the mountain; and the cinders, which were at first gray, notwithstanding that their electricity remained the same, altered to brown, and finally became of a_ reddish colour. These red ashes falling in great abundance, and spreading themselves thickly to a considerable distance, caused great darkness. In addition to this, they observed a strong smell of muriatic acid and of muriate of iron, which reached as far as Naples: had this not been the case, they would yet have discovered from other effects the existence of this acid in the ashes, which had the same day been the sub- ject of their experiments. The pine presented a variety and a remarkable mutability of colours, which are attributed by the authors to the refrac- tions produced in the different currents of air through which they passed. After an abundant shower of rain ae cinders, the Phanomena of Vesuvius. . 49 the trunk of this pine, already much weakened from other cir- cumstances, instead of the cylindrical column presented only a series of large and small globes, which the authors attribute, in great measure, to the enfeebled state of the electric attraction of the air. At the conclusion of the eruption the volcano at- tracted to itself all the clouds of the atmosphere, from which was formed an immense quantity of water, which rolling down its sides in torrents, and carrying with it large quantities.of in- coherent matter, devastated the surrounding country. Of the pisolites, some of them, and those the largest, fell already formed; the others were formed upon the ashes which covered the ground by means of a fine rain. - Section 3d. “ Observations and Experiments made during the Eruption of October 1822.” This section is the longest, the most interesting, and contains the greatest variety of new facts. The following are the titles of its principal divisions: Art. I. * Periods of the Maximum and Minimum of Violence which this Eruption presented. In this is given in detail the fact that the paroxysms appear subject to this general law, that their violence is in the inverse ratio to their duration. The shortest and most terrible are in the middle of the eruption ; the longest and feeblest, at its commencement and at its close. Art. IL. * State of the Crater and of the great Cone on. the 16th of November 1822.— Description of the Cone and of the actual Crater.” The Atrio became more and more filled up, and Vesuvius, properly so called, and Mount Somma were ap- proaching to union. ‘The edge of the crater in question was very narrow. The authors have given in this part a review of the obser- vations made upon the height of Vesuvius from the year 1749 to 1822. Art. III. “ Examination of the Substances which are ejected or produced during the Eruption.” These are di- vided into five classes: 1. incoherent solids; 2. liquids; 3. volatile substances; 4. gaseous substances; 5. imponderable substances. Each of these classes is examined separately and in detail, and the various modes and periods of their ap- pearance are pointed out. The ashes have been carried as far as 105 miles in almost all directions; and the strata which are the result of them, as well as those consisting of other incohe- rent matter, are studied under various aspects, and are ob- served to differ greatly from those formed by alluvial deposi- tion. The effects of these showers of ashes on organized bodies are again spoken of. The currents of lava form sub- ‘Vol. 63. No. 309. Jan. 1824. G jects 50 Mr. F. Baily on the ensuing jects of consideration in the article on liquid substances. Water is an important agent, mechanically and chemically, among those of a volatile nature. Among the gaseous sub- stances, muriatic acid is evolved at all periods of the eruption, and at all temperatures. Art. [V. Of the Currents of incoherent Lava. Art. V. Of the Currents of Ashes. Art. VI. Ofthe Aggregates formed by those Substances. Art. VIL. Of the Mofette produced by the Carbonic Acid. Art. VIII. Of Obsidian, a rare Species of Lava at Ve- suvius. In Art. IX. is given A Catalogue of the Products of the Eruption of October 1822: In Art. X. the Details of the che- mical Processes, which they followed in their Analytical Exa- mination of the Substances produced in this last Eruption. Art. XII. contains two tables of Meteorological Observa- tions made during the months of October and November 1822, at the Observatory of Naples, at the distance of about eight miles from Vesuvius. It also contains a recapitulation of the most remarkable facts observed in the course of the last erup- tion, and since that period. The figures represent, 1st, Vesuvius viewed from the road of the Hermitage a few days before the eruption of October 1822; 2d, this eruption observed from the same situation at eight in the evening; 3d, the Volcano seen from Bosco-tre- Case; 4th, a drawing of the Crater made upon the spot, on the 16th of November 1822. XI. On the ensuing Opposition of Mars. By ¥. Batty, Esq. F.RS. Read before the Astronomical Society of London, January 9, 1824.* T a time when we have two new and excellent observa- tories established in the southern hemisphere, where the celestial phenomena are watched and observed with the greatest diligence and zeal, it becomes the more important and necessary that corresponding observations of a certain class of those phznomena, of not very frequent occurrence, should also be made in the northern hemisphere, by such persons as are fortunately possessed of the requisite means for this purpose. Without this co-operation, the labours of those industrious observers will lose much of their value, and the advantageous opportunity of elucidating an important * See our report of the proceedings of the Society at page G61. branch Opposition of Mars. 51 branch of physical astronomy will be wholly lost to the public. The ensuing opposition of Mars, on the 24th of March, is one of this class: a phenomenon which occurs once only in a period of about 780 days. It is well known that correspond- ing observations of this planet, in the two hemispheres, as compared with stars situated near its path, about the period of its opposition, will serve to determine its parallax. And the parallax of Mars being known, that of the sun may thence be deduced. This was the plan adopted by Lacaille, when he was at the Cape of Good Hope, in the year 1751: since which period, the method has fallen into disuse, for want of an observatory in the southern hemisphere, with instruments fit to be compared with those in Europe. The present period seems extremely favourable (for the reasons above mentioned) for the revival of this method. At the time of the last opposition in 1822, I ventured to draw the public attention to the subject, by pointing out certain stars, near which the planet would pass; and with the posi- tions of which it might be compared. Several valuable ob- servations were made both in the southern and in the northern hemisphere, which are published in various periodical works : and which, being thus recorded, may be referred to with advantage, by those who devote themselves to this branch of physical astronomy. At the present opposition, there are but few stars, and those of inferior magnitude, with which Mars can be advantageously compared. For ten days preceding and subsequent to the date of its opposition, Mars will not approach near to any star given in the large catalogues of Bradley or Piazzi. There are, however, five stars given in the catalogues of Lalande, inserted in the Connaissance des Tems for the years VIII. and XIII. with which the comparisons may be made. The mean places of these stars, on January 1st of the present year, are given in the following little table; together with the dates when Mars will be in conjunction with them. Conn. des Tems.| Mag. R. | D. | Mars. H. M.S. Pat iow An. XII. 78 {12 10 0 | 2 18 44.NJ April 1 XU. 8 14 29 |1 52 2 March 29 XII. 8 17 ,.16.",| 1,:29).47 -— 2 VILL. 7 20 8 aay -—— 25 XIII. 67 29 56°|0 6 44 -— 19 G2 Whe 52 Notices respecting New Books. When Mars approaches either of these stars, the observer should, with a micrometer, measure their distance in a direct line; or take the differences, in right ascension and declina- tion, between the planet and the star: the place and the cor- rect time of observation being noted down. Accurate observations of this kind are of great importance in astronomy: and as nothing tends so much to further such objects as a previous announcement of the phaenomena about to take place, I trust I need not make any apology for drawing the attention of the members of this Society to so interesting a subject. The diameter of Mars, on the day of opposition, will be 13",91. XII. Notices respecting New Books. Recently published. A Practical Essay on the Strength of Cast-Iron and other Me- tals, §c.; the 2nd Edition, 8vo. By Tuomas TREeDGOLD, Civil Engineer, Sc. HIS importantly useful Work, came under our notice too late in the last Month, to admit our doing little more in p- 451, than announcing its publication: we now therefore resume the subject, with reference to the account we gave of the 1st Edition, in p. 137 of our 60th volume, in order to no- tice, the new matters dispersed through the present Edition, which seems collectively to amount to about 130 pages. Instead of the former seven Sections, the work now consists of eleven such, viz. an entire new sixth Section has been in- serted ; the matter of the former sixth Section has, with a great deal that is new, been distributed into four others, which are numbered VII, VIII, IX and X, and the former seventh Section is now the XIth. Very judiciously, as regards refer- ences, and the quotings of this Work by other Writers (which cannot fail we think of becoming numerous), no altera- tions have been made of the former division of the Work into 304 Articles, as numbered in the Margin; but between these Arts. in various places, the principal new matter has been in- troduced, and numbered and distinguished thus, viz. 6, fol- lowing Art. 6; 8* following Art. 8: 19? and 19°, following Art. 19, &c. And the alphabetical Table of Data, which follows Art. 304, might, advantageously for references, have its Articles numbered, in continuation, viz. 305, 306, &c.; and in a future Edition we hope this will be done. In Notices respecting New Books. 53 In Section I. Art. 6, an important Table, as to the saving of calculation it effects, is now added, to show the load or pressure in hundred-weights, while a cylindrical Pillar, Co- lumn or Post of Cast Iron (without enlarged ends, or an at- tached Base or Cap) will sustain with safety, when of any of the several given diameters from 1 inch to 12, and lengths from 2 to 24 feet of Column. Art. 8? contains the descrip- tion of this third Table; and two practical Examples for ex- plaining its use, will be found in Art. 19°. In a Note in page 9, Mr. Thomas Farnolls Pritchard, a Shropshire Architect, who died in October 1777, is stated to have been the pro- poser and designer, in 1773, of the jirst Cast Iron Bridge which was anywhere erected, viz. over theSevern near Brose- ley and Colebrook-dale, and that Mr. A. Darby, to whom (by the Society of Arts) this merit has been assigned, merely, as a speculator, furnished part of the Money for carrying Mr. Pritchard’s design into execution, under the superin- tendence of a Mr. Daniel Onions, in 1777. In Section II, in Art. 15 is described, a new and very sim- ple and durable Weighing Machine, for Waggons, Carts, &c. not exceeding 4 Tons: it is founded on the direct propor- tionate flexure and return, of a Cast Iron Beam (or two such) 16 feet long, 7 inches broad, 5 inches deep in the middle and 24 at its ends, where it is supported. The descent of the middle point, with a 4 Ton load, would be 1:7 inch: which, when multiplied 5 times by a Lever, would cause an Index to move, one-tenth of an inch for each Cwt. of load. Art. 19? explains the use of Table II, in the case of a Load uniformly distributed over the length of a Beam (like that of the weight itself of a heavy Beam) and directs, half of this load to be considered, as acting on the middle point of the Beam, when supported at its ends: In a future Edition it may, for the satisfaction of the practical Man, be well, to explain here in words, why half the uniformly distributed load, is to be used in applying Table II, and why jive-eighths of sucha load is to be used, in applying Table I, Arts. 18 and 19. In this Section, the number of popular Examples is much in- creased. In Section IV, Art. 34° Mr. Tredgold explains a new principle of constructing Cast-iron Bridges, which would not be affected by contraction and expansion, such as has im+ paired several of our finest constructions of this kind: a large Bridge on this construction, might be put together in parts, and erected without the assistance of centering. In Section V. Arts 59° to 59", the Author’s latest Expe- riments are detailed. on 12 Specimens, of 6 different kinds of Cast 54 Notices respecting New Books. Cast Iron: three of these kinds were run by Mr. F. Bramah, from the Pigs of different Furnaces in Shropshire and in . Derbyshire ; one was from re-melted old Iron scraps ; another kind consisted of new Pig and old Iron, in equal parts; and the last pair, of Pig Iron 5th alloyed with Copper. These experiments and the practical results which Mr. Tredgold draws from them, appear to us highly important ; and so do the seven new Experiments by Mr. Bramah, on the Twisting or 'Tortion of Cast Iron, given in Art. 67%. Art. 68? concludes this Section, with a’ set of new Rules, for judging of the quality of Cast Iron by the aspect of a newly fractured surface thereof, as to colour and lustre. “ The colour of Cast Iron, is various shades of gray, some- times approaching to dull white, sometimes dark iron gray with specks of black gray. The lustre of cast Iron differs in kind, and in degree: it is sometimes metallic, for example like minute particles of fresh cut lead, distributed over the fracture; and its degree in this case, depends, on the number and size of the bright parts; but in some kinds, this lustre seems to be given, by facets of crystals, disposed in rays; I will call this lustre crystalline. “‘ In very tough Iron, the colour of the fracture is uniform dark iron gray, with abundance of metallic lustre. If the colour be the same, but with less lustre, the iron will be soft, but more crumbling, and (will) break with less force. If the surface be without lustre, and the colour dark and mottled, the Iron will be found the weakest of the soft kinds of Iron. “ Aoain, if the colour be of a lighter gray, with abund- ance of metallic lustre, the iron will be hard and tenacious : such iron is always very stiff. But if there be little metallic lustre, with a light colour, the iron will be hard and brit- tle: it is very much so, when the fracture is dull white; but in the extreme degrees of hardness, the surface of the frac- ture is grayish white, and radiated, with a crystalline lustre. *‘ There may be some exceptions to these maxims, but I hope they will, nevertheless, be of great use to those engaged in a business which is every day becoming more important.” In previous pages Mr. Tredgold says, “The best and most certain test of the quality of a piece of Cast Iron, is, to try its edge with a hammer: if the blow make a slight impression, denoting some degree of malleabi- lity, the iron is of a good quality, provided it be uniform: if fragments fly off, and no sensible indentation be made, the iron will be hard and brittle.” ** The Tables in this work and Rules, are calculated for soft Notices respecting New Books. 55 soft gray cast Iron: metal of this kind yields easily to the File, when the external crust is removed, and is slightly malleable in a cold state.” Section VI, Arts. 68° to 68', contains Experiments on malleable Iron, English and Swedish, on Steel, on Gun- metal or Bronze, and on Brass: wherein, as to Iron, the ef- fect of hammering and the decrease of force by heat, are ex- perimentally examined, and the cause of English Iron being inferior to Swedish, for particular purposes, is pointed out. The novel and important object which Mr. Tredgold has had in view in all his Experiments, has been, to ascertain the exact strain that Materials would bear, and with what flexure, without impairing their elasticity, so that on removing the strain, this might cause them to recover perfectly, the flexure which the strain had occasioned ; whereas almost all previous Experiments were carried, from 3 to 4 times as far, as to strain, in order to observe, the almost useless point, at which actual breaking took place. In Section VII, and the others which follow, wherever Fluxions have been used by other Writers, in the investiga- tion of the general Formule, the Author has instead, had recourse to the method of progression, which he first de- scribed in 1821, in three papers in our 57th volume. In Art. 121? is now given, a Table of the Thickness, Breadth, and Pitch of the Teeth of Wheels, followed by ample directions and examples of its use; and it is ascertained, that the pro- portions here theoretically assigned, agree very nearly with those, long in use by the most esteemed of our makers of Machinery in the large way. In Art. 139% is now inserted a Table of the proportions of Gudgeons or Pivots, for different degrees of strain or stress: the diameters of the gudgeons in this Table, are from $ to 10 inches, their lengths -43 to 85 inches, and strain from 213 to 85,000 lbs. In Art. 156? the addition is made, of a Table of Cast Iron Joists for Fire-proof Floors, when, besides the flat Brick Arches, the extraneous Load is not to be greater than 120 lbs. on the superficial Foot: At the conclusion of the directions for using this Table, the Author observes * The construction of these Floors, renders a place secure from Fire, without loss of space, and with very little extra expense: it may be of infinite use in the preservation of Deeds, Libraries, and indeed of every other species of property. Ina public Museum, devoted to the collection and preservation of the scattered fragments of literature and art, it is extremely desirable that they should be guarded against Tire: otherwise, they may be involved in one 56 Notices respecting New Books. one common ruin, more dreadful to contemplate than their widest dispersion.” Section VIII treats of the stz/fness of Beams, to resist la- teral Strains, with its application to some interesting practical cases. Section IX is on the strength and sézffness of Beams, to resist Tortion or Twisting, with its application to machinery. Section X treats of the strength of Columns, Pillars and Ties, with several new Examples. What Euler, Lagrange, and other continental mathematicians obtained, from the most refined methods of analysis, is here arrived at and exceeded in accuracy, simplicity and adaption to use. Section XI has been spoken of (as the 7th) in our account of the 1st Edition, before referred to. The Table of Data will be found considerably improved. And at the end is a very copious alphabetical Jndea, which will serve to direct the unlearned or the casual consulter of this useful volume to the particular Table, Example in num- bers, Rule in words at length, or algebraical Formula or Equa- tion, adapted to any required case; calling at the same time his attention to the other cases and conditions, of the same or some nearly similar Problem, from which, the one in hand must be carefully distinguished, in order to avoid error, by the application of a wrong Rule. We deem every Book, materially defective, which appears without a good alpha- betical Index. We are glad to observe, at the end of the Preface, that a second Volume or Part of this Work on Cast-iron and other Materials, is in preparation, treating on the strength of Pipes, Mains, Tanks, Boilers, &c.: of Chains to resist impulsion and pressure: of Suspension and other Iron Bridges: and of framed work for Roots, Bridges, Mills, and Machinery. At the end of this Volume, we observe also, that Mr. Tredgold has in advanced progress, “ Principles of Warming and Ventilating Public Buildings, Dwelling Houses, Manu- factories, Hospitals, Stores, Conservatories, &c., and of con- structing Fire-places, Boilers, Steam Apparatus, Grates, Drying Rooms,” &c. A Synopsis of the Prices of Wheat and of Circumstances af- fecting them; particularly of the Statutes which relate to it Jrom the Commencement of the Thirteenth Century to the End of 1822: Exhibiting in one view the Market Prices as they occurred and as expressed in the present Value of Money. Together with Statements which indicate the Situation of the Country A Notices respecting. New Books. 7 Country as to its Agriculture, Commerce, and Manufactures, Population, Public Revenue, &c. These Tables are evidently the result of extensive research and careful calculation. They form a body of valuable do- cuments on the main branches of our national wealth, and they can never fail being referred to with advantage on sub- jects of similar inquiry. The Author we understand to be recently deceased. He must have been a man of great indus- try, and of no commen powers of mind. He seems to have flinched from no labour in the prosecution of his subject, and he has certainly bequeathed to his country a very important collection of facts in our political economy. The price of the work, considering its details, its size, and execution, is un- usually low. ——= Works in the Press. The following Works are preparing for publication, in quar- terly numbers, by Mr. J. I’. Stephens, F.L.S., &c. A Catalogue of British Insects, or an Attempt to arrange them according to the Natural System ; with the Synonyma for the principal Authors inserted. _ Illustrations of British Entomology, in which it is proposed to give the generic and specific characters of all. the Insects ~which have ‘hitherto been discovered in Great Britain and Ire- land, and observations on their metamorphosis, food, econo- my, &c.; accompanied by Figures of the more alee and in- teresting Species. A Monograph on the British Species of the Linnean Genus Sphinx, embellished with correct representations of all the known Species, their larvee and pupzx ; to which will be added an Appendix, containing a notice (with the characters and figures) of such congenerous Insects of this group as are usually, from bad taste, placed in British Cabinets, either as authentic indigenous specimens or in lieu thereof, to the utter confusion of our knowledge of their geogr aphical distribution. The Author’s intention, we understand, is to publish the 1st number—of the Catalogue on the 1st of May next—of the Illustrations on the Ist of June—and of the Monograph on the Ist of July, following, and to proceed quarterly with each work until completed. The last work will be in 4to, the others in 8yo. ANALYSIS OF PERIODICAL WORKS ON NATURAL HISTORY. Curtis's British Entomology. No. 1. In the present improving state of Entomology in this coun- try, when so much attention has been drawn to this curious and interesting branch of Natural History by several distin- guished labourers in this field of science, a work on British Vol. 63. No, 809. Jan. 1824. H Insects, 58 Analysis of Periodical Works on Natural History. Insects, in which the Genera should be established and eluci- dated by elaborate dissections, was certainly much to be de- sired. This want seems likely, if we may judge from the first Number now before us, to be well supplied by Mr. Curtis ; whose accurate and beautiful Figures are accompanied by full descriptions and elucidatory observations, which evince a cri- tical acquaintance with their subjects. Mr. Curtis’s plates also contain representations of the Plants upon which the insects feed, or to which they are attached, executed with the scien- tific accuracy which has long distinguished his drawings for the Botanical Magazine. It may be observed, that no one could expect to see the completion of a work upon Species in the present advanced state of science; whereas a work limited to Genera may be perfected in a reasonable time, and will be of more real utility. . The following are the subjects of the five plates in the first Number: Cicindela sylvicola. This is a beautiful species, unique as British, and has only been figured on the continent by Megerlé.—Velia rivulorum has, we believe, never before been figured : it is a pretty insect, and has been con- sidered very rare.—Deilephila Euphorbia is a most beautiful and rare spe- cies of Sphinx, and a British specimen of the caterpillar has never before been figured. Euphorbia Paralias, embellishing the drawing, is a most luxu- riant specimen of that local plant.— Peltastes Pini, a new species of a genus proposed many years ago by Illiger, which Mr. Curtis has endeavoured to establish by very elaborate dissections. The Ichneumonidz being ill under- stood, the information contained in this article will be very useful.—Cteno- phora ornata is also unique in Britain, and is very beautiful compared with most of the Tipulidz of authors ; which, however, are all elegantly formed, although the pain which some of them inflict makes them dreaded in warm countries ; but this does not apply to the genus Ctenophora. The palpi are described as being flexible like the trunk of an elephant, which is very un- common, and has, we believe, not before been noticed. The Botanical Magazine. Nos. 442, 443. Pl. 2441. Melastoma granulosa.—Oxylobium arborescens.—Cissus quinque- folia, “ foliis quinatis : foliolis utrinque attenuatis acuminatis serratis pedi- cellatis, ramis teretibus nodosis lwvibus:” from Rio Janeiro.— Biscutella hispida.— Erodium Gussonii, “ pedunculis longissimis multifloris, foliis petio- latis cordato-ovatis inciso-lobatis crenatis, utrinque villosis, caule ascen- dente hirto :”” sent to Professor Tenore, from Avellino in Sicily, by his pu- pil Gussoné, who is engaged upon a new Flora Sicula.—Ipomea speciosa, Convolvulus speciosus Willd. Pl, 2447. Protea grandiflora, « latifolia.—Amethystea cerulea—Phlo- mis Herba venti, of which it is strange that there should have been no figure but the wood-cut of Lobel.—Ononis hispanica.— Coreopsis lanceolata.— Oci- mum canum “ stamineum ; foliis oblongo-ellipticis serratis canis longe pe- tiolatis, spicis verticillatis, verticillis subsexfloris, staminibus corolla bis lon- gioribus.”—Jonidium Ipecacuanha, 8. (Viola Linn.}—Desmanthus virgatus. The Botanical Register. Nos. 105, 106. Tab. 748. Erinus Lychnidea,—E. capensis Linn., distinguished by Mr. Lindley from africanus by the pubescent tube of its corolla.— Tilandsia. . flexuosa Analysis of Periodical Works on Natural History. 59 flexuosa v pallida, “ floribus pallidis, spicA sub-simplici:” probably, Mr. L. thinks, a distinct s»ecies.— Erythrina speciosa.—Dimella strumosa, “ foliis leté viridibus, omnino lzvibus (latitudine, ubi Jatioribus, subunciali): pa- nicula laxa, numerosa, decomposita: corolle pen !ulo-cernuz laciniis re- flexis, alterné saturatits 3-5-lineatis: filamentis cum struma obesa satura- tits colorata antherifera apice articulatis: pedicellis flore paulé breviori- bus,” lately observed in New South Wales by Mr. Cunningham, and does not seem reducible to any of the seven species of Mr. Brown.—Schizopeta- lon Walkeri, introdiaced from Chili by Mr. Francis Place ; an elaborate cha- racter by Mr. Brown accompanies the description. — Ocymumn: febrifugum suf- fruticosum pubescens, “ foliis ovato-lanceolatis crenatis peticlatis, verticillis terminalibus racemosis, bracteis rhombeis deciduis, corolla calyci subaequali.” From Sierra Leone. Very similar to O. heptodon of M. de Beauyais.— Cur- culigo latifolia. Pl. 755. Stapelia normalis.—St. hirsuta, var. atra. We are glad to see this genus preserved entire.— Gnidia denudata, “ foliis oblongis quadrifariam imbricatis pilosis trinervibus: nervis denudatis, flori’yus terminalibus villo- sis: villis sparsis patentibus.’”-—A//ium Cowani, “ scapo nudo semiterete, fo- liis lanceolatis acuminatis flaccidis ciliatis vaginantius, umbella fastigiata, petalis obtusis.” From Peru.—Pleurothallis punctata.— Ponthieva petiolata, “spica laxa erecta, foliis petiolatis erectis crispis glabris, floribus discolori- bus :” brought from St. Vincent’s by Mr. M‘Rae.— Polygala paniculata. Sowerbys Mineral Conchology. Nos. 75, 76. No. 75, Pl. 432, &c. Pileolus, a new genus of fossil shells, of which two species are represented, P. plicatus and levis: the plat, we observe, is the same that was employed in No. 19 of the Genera of Shells by Mr. G. B. Sowerby : their descriptions are of course somewhat enlarged beyond the limits of a work solely illustrative of Genera.—TJ'urbo conicus, and J’. rotun- datus, from the green sand.— Murex peruvianus, and M. tortuosus, crag fossils . the first has a recent analogue in the West Indian seas, P].434, 435, 436, contain ten species of Terevratulz, of which the descrip- tions are promised in No. 76. No. 76, Pl. 438, &e. Terebratule obesa and bucculenta; Mytilus edentu- Jus, lanceolatus, and sublevis ; Inoceramus cordiformis ; I. Cuvieri-and Bron- gniarti; I, mytiloides. These ave several species of a remarkable gigantic. Genus, formerly considered, from the fibrous structure of its shell, to belong to Pinna: it is peculiar to chalk, and one or two contiguous strata. The reference made by Mr. Sowerby to the mountain limestone seems rather too hasty.—Crenatula ventricosa. Tunis Genus has not before been observed among fossils. G. B. Sowerby’s Genera of Recent and Fossil Shells. No. XX. of this useful work contains the following Genera: Cardita, united to Venericardia ; Cypricardia ; Thecidium, a new genus of Brachio- oda, separated from Terebratula by M. de France, aad distinguished from it by the manner of its adhesion, and to which two or three very singular Maestricht fossils belong; Zostellaria; Strombus ; and Pteroceras. XIII. Proceedings of Learned Societies. ROYAL SOCIETY. Jan. 8 EAD, Observations on the Positions and Distances and 16. of 380 double and triple Fixed Stars, made in the years 1821, 1822, and 1823; by J. I’. W. Herschel, Esq. F.R.S., and J. South, Esq. F.R.S. H 2 Jan, 60 Royal Sociely.—Linnaan Society. Jan, 22.—A paper was read, On the Cause of the Corresion. and Decay of Copper used for covering the Bottoms of Ships, by the learned President, Sir H. Davy, Bart., in which he pointed out a simple and ceconomical method of remedying this evil. ‘The cause, he ascertained, was a weak chemical ac- tion, which is constantly exerted between the saline contents of sea water and the copper, and which, whatever may be the nature of the copper, sooner or later destroys it. ‘The same general principle of the manner in which chemical changes may be exalted, destroyed, or suspended, by electrical powers, which led him to the discovery of the decomposition of the al- kalies and the earths, likewise afforded him this new and more practical discovery. He finds that a very small surface of tin or other oxidable metal any where in contact with a large surface of copper, renders it so negatively electrical that sea water has no action upon it; and a little mass of tin brought even in com- munication by a wire with a large plate of copper, entirely pre- serves it. By the desire of the Lords of the Admiralty, he is now bringing this discovery to actual practice on ships of war. It is needless to point out the uses and ceconomical advantages of a result which must add so much to the permanency and strength of our navy and shipping, and be so beneficial ta our maritime and commercial interests. The reading was commenced, likewise, of a paper On the Development of Magnetism in Iron and Steel, by Percussion ; Part 11; by William Scores jun. Esq. F.R.S.E. LINNEAN SOCIETY. ‘Jan. 21.—A communication from Mr. Jonathan Couch, T’.L.S., was read, “On a new Species of the Genus Gadus.” This diminutive species, called by fishermen the Mackarel Midge, is only an inch and a quarter in length, the propor- tions being near to those of the Whiting. : Part of a paper, communicated by the Zoological Club of the Linnzean Society, was also read, On the Natural Affinities that connect the Orders and Families of Birds. By N. A, Vigors, Esq., M.A. F.L.S. The following were among the presents on the table :—A Collection of Birds, including several species of Gull, among which was a specimen of Larus Sabinz ; a box of Minerals, - and a skull of the Walross, Trichecus rosmarus, presented by Mr. Mogg, one of the gentlemen who accompanied Capt. Parry in his late voyage. Also, a specimen of Syren lacertina, and a new species of Cyprinus viviparus, from, Don Vincente de Ceryantes, Professor of Botany in the University of Mexico. ASTRONO- Asironomical, Horticultural, and Meteorological Societies. 61 ASTRONOMICAL SOCIETY. Jan. 9th.—The Papers read at the Meeting of this evening were as follow: ~ Ist. Observations of the Comet of 1811, taken at the Ha- vannah, by Don Joseph Joachim de Ferror, of Cadiz, de- ceased, communicated by the President. These observations were accompanied by computations of the Comet in an elliptic crbit, and the elements are very nearly the same as those brought out by M. Argelander. . . o - . 2d. On the Constants of Deviation occurring in the Reduc- tion of Astronomical Observations. By Benjamin Gompertz, Esq., F.R.S. and M. Ast. Soc. This paper examines the causes of deviation, and proposes formulze for their more easy reduction: it is however so purely mathematical as not to admit of abridgment within our limits. 3d. On the ensuing Opposition of the Planet Mars on the 24th of March next. By Francis Baily, Esq., F.R.S., WoT Ast. Soc. s As this paper contains some valuable observations upon an interesting phenomenon shortly about to take place, we have obtained permission to print it at full length, and it will accordingly be found at page 50 of our present number. We understand likewise, that the Society have come to the reso- lution of printing all papers read before it monthly, after the ensuing Anniversary, fistead of withholding them for an an- nual volume. HORTICULTURAL SOCIETY. Jan. 6.—His Majesty the King of Wurtemberg was elected a Fellow of the Society; and the following déommuiiications were read: — On the Classification of Peaches and Nectarines. By Mr. George Lindley, Corresponding Member of the So- ciety. — Description and Plan of a Pine Stove constructed in the Garden of Richard Forman, Esq. F.H.S. Jan. 20.—The following communication was read :—On the Treatment of the Banyan Tree, in the Conservatory, so as to give it its natural mode of growth. By Capt. Peter Rainier, RN., F.HLS. METEOROLOGICAL SOCIETY. A Third General Meeting of this Society was held on Jan. 14, when the Code of Laws alluded to in our last num-. ber was adopted ; and the Meeting having been resolved into an ordinary one, a Preliminary Report from a Committee was read, on the objects to which the Socicty’s attention should first be directed; a Paper on the Vernal Winds, by Jobu 62 Medico- Botan. Soc.—Roy. Inst. of G. Brit—Fr. Acad. John Gough, Esq. of Kendal; and various other communi- cations. ~ = MEDICO-BOTANICAL SOCIETY OF LONDON. This Society held their Anniversary Meeting on Friday the 16th of January, when the following Council were elected for the ensuing year, viz. President—Dr. Bree, F.R.S. Vice-Presidents—Dr. Paris, F.R.S.; Dr. E. T. Monro; Joshua Brookes, Esq. F.R.S.; Wm. T. Brande, Esq. F.R.S.; Sir James McGregor, M.D. F.R.S.; Sir Alex. Crichton, M.D. F.R.S. Treasurer —Wm. Newman, Esq. Secretary. —Mr.C. Holdstock. Professor of Botany.—John Frost, Esq, Council—Thomas Jones, Esq.; Wm. Yarrell, Esq.; ‘Uhos. Andrews, Esq.; Anthony White, Esq.; Dr. John Elliotson. ROYAL INSTITUTION OF GREAT BRITAIN. The Lectures at this Institution will commence early in the month of February, and the following Courses are announced for delivery in the season, viz. On Electricity, Electro-Chemistry, and Electro-Magne- tism. By W.T. Brande, Esq., Sec. R.S. and F.R.S.E., Prof. Chem. in the Royal Institution To commence Saturday, 7th February, and continue each Saturday. On Mechanical Philosophy and its recent Improvements; particularly in Optics and Hydraulics. By John Millington, Esq. F.L.S., Sec. Ast. Soc., Prof. Mech. in the Royal Insti- tution.—To commence Thursday, 12th Feb., and continue each Thursday. On Botany and Vegetable Physiology. By John Frost, Esq., Prof. Botany to the Medico-Botanical Society of Lon- don.—To commence after Easter. On Plane Geometry. By Jobn Walker, Esq., of Trin. Coll. Dublin, M.R.L.A.—To commence after Easter. On Music. By W. Crotch, Mus. Doc., Prof. Music in the University of Oxford.—To commence after Easter. All the Lectures commence at 2 o’clock. ROYAL ACADEMY OF SCIENCES OF PARIS, July 7.—The Academy received from M. Becquey, direc- tor-general of bridges and roads, some Researches on the uniform Motion of incompressible and homogeneous Fluids, by MM. Lamé and Clapeyron; also a new Memoir from M. Ar- noul senior on Equations of three ‘Terms of the second Degree. M. Moreau de Jonnes read part of a third Memoir on the Geography of American Plants, entitled, Researches on the Conditions of Vegetable Organization necessary for the geogra- phical Transfer of Plants by Animals and by Men, M. Gay- ‘The Comet. 63 M. Gay-Lussac read a Memoir by MM. Boussingault and Rivero on the Milk of the Cow Tree. MM. Humboldt and Arago mentioned that those gentlemen, Professors of Chemis- try at Santa Fé de Bogota, had just sent some interesting ob- servations on the mean height of the barometer at the level of the sea between the tropics; on its hourly variations; on the hot springs of the Cordilleras ; on the geographical posi- tions of various places, &c. &c. M. Becquerel read a Memoir on the electric Effects deve- loped in various chemical Actions. ‘The Sitting finished by. the reading of a Memoir by Mr. H. M. Edwards, on the ele- mentary Structure of the principal organic Tissues of Animals. July 14.—Specimens were received from the director-gene- ral of mines of the Sal gem, from the mine lately discovered in Lorraine; he requested that an analysis of it should be made by a Commission of the Academy ; and stated that the Minister of Finance would publish their Report. M. Arago communicated a new Note of M. Becquerel on his electro-magnetic experiments. M. De Ferussac read a Note on the Shells found in the Nile by M. Caillaud, and which had been erroneously regarded as oysters; they are hétéries of Lamarck. M. Gaymard read a Memoir on the Growth of Polypi geo- logically considered. M. de Jussieu jun. read a Memoir on the Family of Eu- phorbiacez. XIV. Intelligence and Miscellaneous Articles. THE COMET. Gosport Observatory, Jan. 26, 1824. HE following observations on the present COMET are at your service, if you think them worth a place in your Journal, and have not received a more satisfactory account from any of your Correspondents. _ It was first observed here in the morning of the 29th of December, 1828, when its nucleus appeared ill defined, and no larger than a star of the third magnitude, and its train was only 23 degrees long. ‘The following memoranda will show its position from time to time, and its progressive antecedental motion under the fixed stars. Monday Morning, Dec. 29th, 1823, its Right Ascension was 251° 15’ = — its Declination 8 30 north. Sunday Morning, Jan. 4th, its Right Ascension was 249 OO a —_—— its Declination 18 12 north. Monday Morning, Jan. 12th, { 1 go4 its Right Ascension was 243 30 —_—. “" its Declination 82 50 north. Friday Evening, Jan. 234, its Right Aseension was 217 20 ; —— -_——— its Declination 63 45 north. ~ lor B4 The Coniet. For the first 13 days, that is, from December 22d 1823 to January 4th 1824, its motion under the fixed stars was at the rate of 1° 31’ per day. From the 4th to the 12th of January its daily motion was 1° 58’; and from the morning of the 12th, to the evening of the 23d of January, its velocity through the heavens increased to 2° 36' per day. ‘These cer- tainly are great inequalities. Its present motion is twice as great as when it was at its perihelium, and its nucleus gets larger and its tail longer as it recedes from the sun, which are anomalies not easily to be accounted for; as they do not seem to arise from any inclination the comet has towards the earth, because it is approaching its aphelium. The speed of this comet outstrips all that have been ob- served here for many years past, not excepting that of the brilliant comet in the autumn of 1811. It now being a circumpolar object, at least in this latitude, it may therefore be seen soon afier sunset, and throughout the night in clear weather. It is now (January 26th) in the tail of Draco, between the head of Ursa Minor and the tail of Ursa Major, and by the end of the month it will be at or near the last star in the tail of Draco, and about 21° under Polaris, in the evening. From the preceding remarks I have found that it must have crossed the Equinoctial about the 22d of December 1823, when its distance from the sun was about 274 degrees, which may be considered as its perihelion point. Wo. Burney. ———— Inchbonny, Jan. 13, 1824. The comet a few days hence will be within the circle of perpetual apparition, and will be continually above the hori- zon, and so never set. At present it rises between the N.N.E. and N. by E. about 15 minutes past 10 at night, and comes to the meridian about 45 minutes past 8 in the morning, and sets between the N.N.W. and N. by W. at 35 minutes past seven at night. Its correct distance was, on the 10th January, 17 hours 30 minutes mean time; from Arcturus 32 deg. 48 min. 16 sec.; from Lyra, 26 deg. 38 min.; and from Rasal- hagus, 22 deg. 50 min. The earth travels nearly at the rate of one million and a half of miles per day in its annual course round the sun, and the earth’s mean daily motion is nearly 59 minutes and eight seconds; but the daily motion of this comet at present is 112 minutes, which is nearly double that of the earth round the sun. About six o’clock in the morning the planet Venus will be seen on the south-east, and the planet Mars a little past the meridian, and nearly in conjunction with Astronomical Information. 65 with the star marked gamma in Virgo, and Jupiter near his setting in the west. Jas. VEITCH. P.S.—On the 13th instant, about thirty minutes past six, a large fiery meteor, with an oval head larger than the full moon, and a long and sparkling tail, appeared to come from the west, and moved toward the south-east, in a curve line, with its convex side to the north.—-J. V. The comet on the 7th of January was in the right shoulder of Hercules, taking a direction towards the tail of the Dra- gon. It moves with astonishing velocity, as it has since passed midway between the back of Hercules and the northern crown, through the right leg of Hercules, and is now con- tinuing its course between the right knee of Hercules and the right hand of Bootes, and at the present time does not set. If the brilliancy of the comet continue, we may expect a more favourable opportunity of seeing it about the 30th of this month, when the moon will be absent; and should the atmo‘ phere be clear, it will then be distinctly visible between the Pole and the extremity of the tail of the Ursa Major, at any hour of the night. ASTRONOMICAL INFORMATION. M. Schumacher’s Astronomical Tables for 1824 have at length arrived, and may be had of Messrs. Treuttel, Wurtz and Co.: accompanied with an English translation. They contain the usual tables, which will be found of constant use in an observatory. : M. Schumacher has communicated to the Astronomical Society of London, the elements of the present comet, deduced from his own observations and those of M. Bouvard at Paris. M. Mossotti, who is now in England, is engaged in a similar undertaking from observations made in this country. COMET OF SEPTEMBER 1822, OBSERVED AT PARAMATTA. The followimg are the elliptic elements of the comet observed at Paramatta by Sir Thomas Brisbane and Mr. Rumker, as communicated to the Royal Society of Edinburgh. Time of passing the perihelion, mean time, Oct. 24,221201 Log. of perihelion on the orbit, . from mean { 271° 36! 183 Log. of descending node equinox, 272 42 23 oakaation Siintihin Mek aloe, obeakboeaehy ort ere Logarithm e (8=82° 53'11”) . . . . >. 9°9966440 Log.4 parameter . .... + + + + 0°3585731 Sidereal revolution in days . . . » .« «+ 663554°3 Edinb. Phil. Journ., vol. x. p. 179. Vol. 63. No. 309. Jan. 1824. I ANOMALY 66 Astronomy. ANOMALY IN THE FIGURE OF THE EARTH. So many ships touch at Madeira, and take a new departure from it, that the longitude of the island is a matter of consi- derable importance. Dr. Tiarks was therefore sent out by the Board of Longitude to ascertain it, with sixteen watches, in the summer of 1822; and a remarkable circumstance occur- red, which was not within the object of his original mission. For, in going from Greenwich to Falmouth, a difference of longitude was found equal to 20’ 11"49; and, in returning from Falmouth to Greenwich, a difference of 20’ 11°13. Now the difference, as determined from the Trigonometrical Survey (given in the third edition of the requisite tables), is only 20’ 69; and this variation made it expedient to engage Dr. Tiarks to verify his observations in the Channel. He was furnished with twenty-nine chronometers, and was employed from the latter end of last July till the middle of September in sailing between Dover and Falmouth. His results are as follows: Longitude of Dover station . . . ©. . 0" 5¢17"54 E. Portsmouth Observatory . 0 4 24°77 W. Pendennis Castle . . . . 020 10°85 W. Madeira caicosyrpa reipoar ne pe al 7 89°08 W. From hence it is clear that the figure of the earth must be somewhat different from that assumed for determining the lon- gitudes from the Trigonometrical Survey, and that about 5” must be added, in the latitude of the Channel, for every 20’ of longitude which is deduced from it.—dinb. Phil. Journ., vol. x. p. 179. REMARKS ON PROFESSOR STRUVE’S OBSERVATIONS TO DETER- MINE THE PARALLAX OF THE FIXED STARS. BY J. POND, ESQ., ASTR. ROYAL. Of the various attempts to discover the parallax of the fixed stars, the observations of Professor Struve must be regarded as among the best and most judicious. [Obs. Vol. II. III.] His object is, by means of an excellent transit instrument furnished with seven wires, to determine the sum of the paral- laxes of several fixed stars, differing nearly 12 hours in right ascension from each other. The results which he obtains seem to verify a remark which I have often had occasion to make; that in proportion as any improvement takes place either in our instruments or our pro- cesses, the resulting parallax becomes proportionally less. Of fourteen sets of opposite stars thus compared, Mr. Struve finds seven, which give the parallax negative: this circum- stance alone should suggest great caution in attributing to the effects M. de la Place’s Méchanique Céleste. 67 effects of parallax the small positive quantities that are derived from the remaining seven. Mr. Struve however is inclined to assign 0’"16 of space as the parallax of § Ursee Minoris, and 0"-45 for the sum of the parallaxes of « Cygni, and s Urse Majoris. His leamned coadjutor, M. Walbeck, who, it appears, has undertaken the calculations, is disposed to attribute the greatest portion of this parallax to the smaller star: a circum- stance so improbable requires very strong evidence for its support. But whatever reasonable doubt we may entertain as to any one given result * relating to such extremely minute quantities, yet the mean of the whole must be admitted to deserve very great confidence; and it is to this view of the subject (omitted by the learned author) that I wish to direct the attention of astronomers. If we take the mean of the fourteen results as relating ge- nerally to stars from the Ist to the 4th magnitude, it will ap- pear that the mean sum of the parallaxes of two opposite stars is equal to 0'.036 of space, or the parallax of a single star equal to 0’.018. If any reliance can be placed on these observations, every attempt to determine the parallax of these stars in declination must be entirely hopeless; since in this case we can only measure the shorter axis of the ellipse, and the uncertainty of refraction must amount at least to twenty times the quantity we are in search of.—Quart. Journ. of Science, vol. xvi. p. 365. M. DE LAPLACE’S GREAT WORK. The fifth and last volume of the Méchanique Céleste hasmade its appearance, in which the question of the form of the earth is discussed in various new points of view: namely—lIst, The dynamic effect of the presence and distribution of the waters on the surface of the globe. 2dly, The compression to which the interior beds are subjected. 3dly, The change of size, which may result from the progressive cooling of the earth.— The author has arrived at the following results: That the great mass of the earth is by no means homogeneous ; that the beds situate at the greatest depth are the most dense; that those beds are disposed regularly round the centre of gravity of the globe, and that their form differs little from that of a curved surface generated by the revolution of an ellipsis ; that the density of water is nearly five times less than the mean density of the earth ; that the presence and distribution of the * It should be remembered, that in a series of observations, it generally happens that some results will be erroneous by a greater quantity than the mean probable error. 12 waters 68 Algebraical Notation. waters on the surface of the earth do not occasion any. con- siderable alterations in the law of the diminution of the de- grees, and in that of weight; that the theory of any consi- derable displacing of the poles at the surface of the earth is inadmissible, and that every geological system founded on such an hypothesis will not at all accord with the existing knowledge of the causes which determine the form of the earth; that the temperature of the globe has not sensibly di- minished since the days of Hipparchus (above 2000 years ago), and that the actual loss of heat in that period has not produced a variation, in the length of the day, of the two hundredth part of a centesimal second. TO MATHEMATICAL CORRESPONDENTS. To the Editors of the Philosophical Magazine and Journal. Since the invention of fluxions, it has generally been cus- tomary among the mathematicians of this country to denote the fluxion of any quantity, as 2, by the symbol 2, its second fluxion by 2’, its third fluxion by #, &c., as was done by Sir I. Newton: while those on the continent, following the example of Leibnitz, have expressed the same by dz, dx, d*x, which they have called the several orders of differentials of the quan- tity xz. Of late years, however, some of our first mathema- ticians, from a conviction of the latter notation being in many respects superior to the former, have adopted it in their writings; and from the circumstance of its not having been long ago adopted by the mathematicians of Great Britain, some of them even attribute to this cause the comparatively slow progress which the mathematical sciences have made in this country during the last century, to what they have made in France and Germany. Now as the cause of this alleged superiority has never been satisfactorily explained, so far as I can learn, by any English author, except in telling us that it cannot be understood by any but those who have attained a great proficiency in the study of the calculus; I should, there- fore, feel much obliged to any of your dx correspondents to endeavour to furnish something which may throw further light on this subject. Indeed, it has always appeared to me, that if a preference could be given to either of these arbitrary sym- bols, the Newtonian ought to be chosen, as being more defi- nite in its signification, and less apt to produce confusion in the mind of a learner, as the other is apt to convey the idea of a product as well as a differential. I am your most obedient servant, NEW * Capt. Parry's Expedition.— Temperature of theCaribbean Sea. 69 NEW NORTHERN EXPEDITIONS. His Majesty’s discovery ships Hecla and Fury have been recommissioned at Deptford by Captains Parry and Hopp- ner. The latter officer was the first lieutenant on board of Captain Lyon’s ship on the recent voyage. Such is the con- fidence felt in the intrepidity, judgement, and conduct of the distinguished officer in command of the expedition, and in the attention paid by the different naval departments to the com- fort of the men, that no sooner were the ships commissioned, than one-third of the crew belonging to the Fury on the for- mer voyage again volunteered for the Hecla, the ship bearing Captain Parry’s pendant. Captain Lyon at the same time commissioned His Majesty’s ship Griper, which ship is de- stined for Repulse Bay, whence Captain Lyon proceeds over land to the back of that Bay, to survey the coast thence to the “ Cape Twrnagain” of Captain Franklin’s recent discoveries. Captain Franklin proceeds by the way of New York to Fort Enterprize, with a view to survey the coast on the American Continent to the westward, connecting, if possible, the survey between Fort Enterprize and Icy Cape. TEMPERATURE OF THE CARIBBEAN SEA AT THE DEPTH OF 6000 FEET. The following is Captain Sabine’s account of an experiment on this curious subject, as given by him, in a transcript of the original memorandum written at the time, in a letter to Sir H. Davy, published in the second part of the Philosophical Transactions for 1823, p. 207. “«: H. M.S. Pheasant, on passage between Grand Cayman Island and Cape St. Antonio, in Cuba, lat. 204 N., long. 834 W., November 13, 1822. « At 2 P.M. hove to, and sounded with 1230 fathoms of line, being 11 coils of 113 fathoms each, and three fathoms of a 12th coil; at the end of the line was attached a strong iron cylinder of 75 lbs. weight, inclosing a Six’s self-register- ing thermometer: the top of the cylinder screwed down upon leather, being designed, by excluding the water from the in- terior, to obviate any effect which might be supposed to arise from the increased pressure of water at great depths: the thermometer fitted into spiral springs at the top and bot- tom, which kept it from contact with other parts of the cylin- der, and preserved it from injury, in case the apparatus should accidentally strike against the sides of the ship, or against rocks at the bottom: another iron cylinder, of much less strength and weight than the preceding, was attached two fathoms above the end of the line, and being pierced with holes 70 Temperature of the Caribbean Sea. holes in the top and bottom, admitted free access of the water to a second thermometer, of similar construction to the first. The opportunity was very favourable for the object, the weather being fine, with light airs and but little swell: the 1230 fathoms run out in rather more than 25 minutes, at the expiration of which time the line was fairly on the quarter, the ship’s drift having been bodily to leeward, with- out her having had either head or stern way ; there was con- sequently much less stray line than had been anticipated. The best practical judgement which Captain Clavering could form on the spot was, that the depth to which the thermo- meters had actually attained must have exceeded a thousand fathoms, as an allowance of the remaining 230 fathoms for stray line would certainly be more than ample, if no bight of consequence existed in the rope, which, from the appearance, and from the rapidity with which the weight drew out the line, might be judged the case: 230 fathoms would equal a drift to leeward of ths of a mile in 25 minutes, whereas that of the ship did not exceed $ a mile an hour; it is more than probable, therefore, that the depth is underrated when it is estimated at 1000 fathoms, or 6000 feet. The line was hauled in in 53 minutes, and the thermometers came up in good or- der ; the one in the cylinder to which the water had free ac- cess had registered 45°°5; the attempt to exclude the water from the other cylinder did not in this instance altogether succeed, in consequence of the top not having been screwed down sufficiently close upon the leather; this thermometer had registered 49°°5; the difference of 4° may be attributed, perhaps, partly to the latter not having been so long in con- tact with the cold water as the other thermometer, as the wa- ter appeared to have had great difficulty, and was probably some time in forcing its way into the interior of the closed cylinder; and partly to the heat which so great a thickness of metal would retain for a considerable time; the surface water was from 82°°5 to 83°-2 in the course of the afternoon ; the difference of temperature between the surface, and a depth exceeding 1000 fathoms, was therefore 33°-3 by one ther- mometer, and 37°°3 by the other, the indication of the latter being entitled to the most reliance. «It may be reasonably inferred, that one or two hundred fathoms more line would have caused the thermometer to have descended into water at its maximum of density, as depends on heat, below which, consequently, no further diminution of temperature would take place; this inference being on the presumption that the greatest density of salt water occurs, as is the case in fresh water, at several degrees above its freez- ing point.” Debereiner’s Eudiometer. 71 DG@:BEREINER’S EUDIOMETER. “‘ The very remarkable discovery of Professor Doebereiner concerning the relation of the metallic powder of platinum to a gaseous mixture of hydrogen and oxygen,” observes Prof. Gme- lin, “I found confirmed in a splendid, but at the same time ina dangerous manner. I caused a few cubic inches of hydrogen gas to enter into an eudiometer two inches in width, and the glass of which was one line in thickness; and then brought the platinum- powder, wrapped up in white blotting paper, through the quick- silver, into contact with the gas. I then caused oxygen gas to enter into the eudiometer, and when but few bubbles had ascended, a terrible explosion took place, which shivered the glass into a thousand pieces, which were thrown about to the distance of ten feet. It is remarkable that neither myself nor Prof. Boh- nenberger, who stood by, was in the least injured. I do not consider it superfluous to communicate this experiment to you, since it proves that great caution is required in attempt- ing it. In Prof. Debereiner’s experiments, no explosion ap- pears to have taken place. I afterwards made the experiment with hydrogen and atmospheric air, and found that a consi- derable diminution of volume followed ; but it appeared, at the same time, that much of the oxygen remained ; for the residue still exploded strongly by means of the electric spark ; and a considerable diminution of volume again took place. It ap- pears, therefore, that this method will not answer the purpose of an eudiometer. The further results I obtained are as follows :-— 1. It is indifferent whether the hydrogen be first brought into the vessel, the platinum-powder afterwards, and then the atmospheric air; or whether the hydrogen gas and the atmospheric air be first mixed in the vessel, and the platinum-powder then introduced. 2. Much humidity prevents the absorption. 3. Silver-dust (obtained from nitrate of silver by copper) and gold-dust (obtained from muriate of gold, precipi- tated by iron, and purified by hot muriatic acid and water) do not produce the least effect, not even with oxygen gas.” The above is translated from a letter of Prof. Gmelin to Prof. Schweigger, published in the October number of the Neues Journal fiir Chemie, &c. of the latter, who makes the following remark on Prof. Gmelin’s conclusion as to the in- applicability of Deebereiner’s discovery to eudiometrical pur- poses :-—* Under what conditions this may notwithstanding be the case, will be seen in our next, in which will appear an account of the proceedings of the German Explorers of Nature, to 72 Debereiner’s Eudiometer. to whom, on the 20th of September, Prof. Doebereiner com- municated his remarks and experiments.” From Schweigger’s Journal for November, we accordingly extract the following :— “At a meeting of the Society of the Explorers of Nature, held on the 20th of September 1823, Professor Deebereiner fulfilled the promise he made at the first meeting; viz. to com- municate something more respecting his new and important discovery, so fur as it is applicable to eudiometry, and to ex- hibit it by experiments. «The platinum is kneaded up with clay into small balls, which are then brought to a white heat before the blowpipe. Ifsuch a ball, suspended by a platinum-wire, is dipped into an open glass vessel filled with hydrogen and oxygen, the ball rapidly becomes red-hot; during which a cloud of vapour forms itself around it; it then becomes white-hot, and the explosion im- mediately takes place. Such balls answer best for eudiometri- cal experiments made over quicksilver. ‘The decomposition would certainly not be completely effected if the platinum-pow- der, moistened by the water which is formed, ceased to remain hot. But how easy is it in such a case to let another ball be carried through the quicksilver, in case the firstis not sufficient!” No. XXXII. of the Quarterly Journal of Science contains the following article on the same subject :— “‘ Professor Deebereiner has suggested the use of finely divided platina for the purpose of detecting minute portions of oxygen in a gaseous mixture, in which hydrogen also is present. — Its effect is immediate; the moment the substance rises above the surface of the mercury in the tube containing the mixture, the combination of the oxygen and hydrogen begins, and in a few minutes is completed ; and, as Professor D. has stated, it seems capable of detecting the smallest quantity of oxygen. Its utility in the analysis of atmospheric air, and compounds containing oxygen, is obvious, provided no combination also takes place between the hydrogen in excess, and the nitrogen (or other gas) that may be present, as does in fact happen, ac- cording to Deebereiner, when protoxide of platinum is so em- ployed. ‘“‘ Messrs. Daniell and Children mixed 20 measures of atmo- spheric air with 37 measures of hydrogen gas, and passed up to the mixture a small portion of the platina powder, procured by heating the ammonia muriate to redness, and made into a ball with precipitated alumina. The pellet was heated red by the blowpipe, immediately before it was used, its size about that of a small pea. The absorption amounted to 13 mea- sures = 4.3 oxygen, being 0.1 of a measure more than the quantity of oxygen in 20 measures of atmospheric air, which may Benzoic Acid.—Cranbervies. "3 may probably have arisen from a slight impurity in the hy- drogen, or from some minute unperceived bubbles of air en- tangled in the mercury. ‘¢ Another mixture of common air and hydrogen, in which the latter was in considerable excess, was deprived of its -oxy- gen by the pellets, and when the absorption was complete, 38 measures of the residual gas were taken, and a fresh pellet, heated to redness, immediately before it was used, passed up. After standing about a quarter of an hour, no absorption had taken place. The tube and the mercury were then placed be- fore the fire, till the whole apparatus was too hot to be touched -with the naked hand. It was then removed from the fire, and, when cooled to its original temperature, the mixture occupied, as before, exactly 38 measures. The powder of platina with hydrogen seems, therefore, to be admirably calculated for eudio- metrical purposes. Its application is extremely simple and easy; it is speedy in its eifect, and no error need be appre- hended from the formation of ammonia, even at considerably elevated temperatures. It appears also to be well calculated for ascertaining the purity of simple gases, at least as far as regards admixture of atmospheric air. The oxygen of a very minute portion of common air, mixed with carbonic acid gas, and a little hydrogen, was immediately absorbed, on passing up one of the little pellets to the mixture.” BENZOIC ACID IN THE RIPE FRUIT OF THE CLOVE TREE. The clove is the flower bud of the Eugenia caryophyllata, and the ripe fruit was formerly used in medicine under the name of Antophylli. In the latter, Mr. W. Bollaert has ob- served crystals of benzoic acid lining the cavity between the shell and the kernel.— Quart. Journ. of Science, vol. xvi. p. 378. CRANBERRIES. A correspondent who has read Mr. Milne’s paper on the Cultivation of the English Cranberry, printed in Phil. Mag. vol. Ixii. p. 382, from the Horticultural Transactions, wishes to be informed if the Cranberries which are said to be sold in such sarge quantities in the town of Langtown, in Cumberland, be really the fruit of the Oxycoccus palustris, or Vaccinium Oxyeoccus of Linnzus. He suspects otherwise, because he has ascertained beyond a doubt, that what are commonly called Cranberries in Scotland, are the fruit of the Vaccinium Vitis-idea, or Cran- berry, which isa much more common plant than the Oxycocews, and is in the opinion of many persons not less worthy of cul- tivation. Vol. 63. No. 309. Jan. 1824. K THUNBERG’S 74 Thunberg’s Cabinet of Entomology.—Earthquake. THUNBERG’S CABINET OF ENTOMOLOGY. Professor Thunberg, of Upsal, has proposed to sell his large and valuable collection of Insects. It includes every class and order, and is in very good condition. It is one of the most extensive, containing at least between 25 and 30,000 speci- mens: it commenced 60 years ago, and has been continued till the present time; the names of the subjects, and notes on them, are affixed. They are preserved in 84 cases, which contain neat boxes or drawers covered with glass, and having cork at the bottom. Of each species there are in many cases two or more specimens. The class of butterflies is unusually complete, handsome, and enriched with specimens and species the largest and most rare. The new and as yet undescribed species are many. There are specimens of some which are not in any other collection; the collection is rich in those from Japan, Java, Ceylon, the Cape of Good Hope, and South America. This formation has cost the proprietor 10,000 rix dollars, Hamburgh currency, for collections purchased, exclusive of those which he has collected himself. For the whole the pro- prietor expects 2000/. sterling. EARTHQUAKE. Ceylon, Feb. 15, 1823. On Sunday last, about three minutes after one P.M. (mean time), two distinct though slight shocks of earthquake were felt at Colombo, following each other in the course of half a minute. No damage has been sustained either here or in the several other places in the island where it was also felt. We have accounts of the occurrence from Kandy and different places in its neighbourhood, Ratnapora, Matura, Hamban- totte, and Negombo. The phenomena, as described, seem to have been nearly the same every where, and were accom- panied by a rumbling noise as of heavy ordnance moving along the ground. It appeared to move in a direction from the north-west to south-east. Though our correspondents have given us the times at which they observed the occurrence at different places, yet as they have not always distinguished whether the time was solar or mean time, and as the accuracy of watches at out-stations is not always to be relied on, we do not think the data in this respect are given with sufficient accuracy to be useful. The sky was clear, but no greater heat, or other difference of temperature observed from what is usual at this period of the year. LIST ek en LIST OF NEW PATENTS. To Thomas Greenwood, of Gildersoun, near Leeds, machine-maker, and Joseph Thackrah, surgical mechanist, of Leeds, both in the county of York, for their improvements on or substitutes for pattens and clogs. —Dated 27th of December 1823.—2 months allowed to enrol specifi- cation. To John Vallance, of Brighton, Sussex, esq., for his improved method or methods of freezing water.—1st January 1824.—6 months. To Francis Devereux, of Cheapside, London, merchant, for certain im- provements on the mill or machine for grinding wheat and other articles, commonly known by the name of the French Military Mill.—8th January. —6 months. To Joseph Foot, ,of Charles-street, Spitalfields, Middlesex, silk manu- facturer, for his improved umbrella.—1{ 5th January.—6 months. To John White, of the New Road, in the parish of St. Mary-le-bone, Middlesex, architect, for his floating breakwater.—15th January.—2 mon. To John Finlayson, of Muirkirk, Ayrshire, farmer, for certain improve- ments on ploughs and harrows.—1]5th January.—6 months. To Jean le Grand, of Lemon-street, Goodman’s Fields, Middlesex, vine- gar manufacturer, who, in consequence of acommunication made to him by a certain foreigner residing abroad and discoveries by himself, is in posses- sion of certain improvements in fermented liquors and the various pro- ducts to be obtained therefrom, and that the same are new in this kingdom 15th January.—6 months. To William Gutteridge, of Dean-street, St. Fin Barrs, county of Cork, musician and land-surveyor, for certain improvements on the clarionet.— 19th January.—¥ months. To George Pollard, of Rupert-street, in the parish of St. James, Middle- sex, brass-founder, for certain improvements en machines or machinery for levigating or grinding colours used in the various branches of painting, which machinery may be worked by any suitable power and is applicable to other useful purposes.—19th January.—2 months. To James Russell, of Wednesbury, Staffordshire, gas-tube manufacturer, for his improvement in the manufacture of tubes for gas and other pur- poses.—19th January.—-2 months. To Simeon Broadmeadow, of Abergavenny, Monmouthshire, civil en- gineer, for his improved method of manufacturing and purifying indamma- ble gases by the admission and admixture of atmospheric air.—19th January. —4 months. To Howard Fletcher, of Walsall, Staffordshire, saddler’s ironmonger, for certain improvements in tanning hides and other skins.—19th January. —2 months, — Eo 1823. £25 / ESE |< elace|ecelass| 222 |e] ffs S°a/s 5 gos S°Slae° ost s ml 5s gS = Ala als Aal= FSI x Z\s & a PAS) &g January | 29-90| 29:20 42 | 19 131-38] 2°900| 6] 1-547 February | 29-91) 28°88) : 51 26 |35°4 | 5:516| 14] 7°284 March ~ | 30-00} 27-70 52 | 22 |39:5 | 3:053| 10] 9-016 April —_| 29-98) 28-98 56 | 26 |41°51) 3:228| 17] 2:344 May 30°26] 29°15 71 | 31 |51-03f 7043] 18 | 2-277 June 30°15] 29:17 71 | 35 |52:8 | 3-414| 12] 1-584 July 30°02} 29-28] 29°58] 68°5 | 39 |55:4 | 7°858| 24] 8-340 August | 29:97) 29-21 69 | 37 |54°79] 7°750| 27 | 4:297 Septemb. | 30°13) 28-98 68. | 30 [52:4 | 5:742| 17 | 2°869 October | 30:26] 28°62/ 29°52} 60 | 30 |44°8 | 6-218} 18} 8-487 Novemb. | 30°43) 29:00) 29°89} 54 | 23:5 | 42-65} 3:403| 13 } 10°876 Decemb. | 30:20] 28-61/ 29:45! 50 | 18°5/ 38-35} 6°624| 22 | 3-805 62-749 /198 62°726 The town of Kendal, where these observations were made, has long been a point of interest to meteorologists. It is si- tuated nearly at the south extremity of the mountainous di- strict of Westmorland and Cumberland, in the west side of a valley bounded by two chains of hills running from north- east to south-west. Its height above the high-water mark is about 42 yards, calculating from the canal which runs be- tween this town and Lancaster. ‘The prevalent winds in this valley are the north-east and south-west. The latter isthe most prevalent. ‘The former, which may be styled the vernal east wind, prevails here, in common with other parts of the north of England, in the month of April to the 7th or 8th of May, and sometimes much Ionger. Not much dependence, however, can be placed on observations for meteorological purposes, made on the direc- tions of the winds, from the local situation of Kendal, as they will be governed, or at least materially affected, by the direc- tion of the hills which bound the valley. For the last seven months the winds have been remarkably stationary, their di- rection having been, with very little variation, south-west or veering from south to west. The summer and autumnal months have been marked by an unusually low temperature, and by frequent rains. More than the average quantity of rain has fallen during that period, viz. from the beginning of June to the end of Novem- ber. The total quantity in this and the last year has ex- ceeded the average, which, calculating from observations made in Kendal for 16 successive years, may be stated at 49°86 inches. Kendal, 20th Ist month 1824, METEORO- Meteorological Register for 1823.—Scotland. 79 METEOROLOGICAL TABLE. Extracted from the Register kept at Kinfauns Castle, N: Bri- tain. Lat. 56° 23’ 30”. re Ayoyee the level of the Sea 129 feet. Morning, Evening, 10 o’clock. 100’clock. Mean height of \Meanheight 0 Mean } Depth Tempr. of by Six’s} Rain. —_———— | —__—_|-= N° at eee. 1823. |Barom.) Ther. !Barom.| Ther. January . .|29-704/34°387] 29-701|33-581} 33.935 3-50 16 Bebruary: 29.295 |35°393 | 29-294|33-464 | 34-357 3-50 14 March. ...|29-585|40°613[ 29-577 |38-355} 40-350 1.30 12 April a aatas 29-737 |44°830 43-500 1:00 8 May Wiakte% 29-704|52°900 51-710 2-20 14 June... .» |29°74]/55°330 53°533 1-00 11 July pecs 29-565|57:090 j 29-545 |52-900; 56-390 6.35 24 August ...|29-720|56-680 ! 29-640 |52:807{ 55-480 3°50 20 September. | 29-729|54-333 : 29-704 |49-930} 53-100 1-65 14 October. . . | 29-570/46°420| 29-570 |44-350! 45-870 3.55 10 November. | 29-902/46-300} 29-886 |45-760! 46-333 1-45 8 December . | 29-415/39°193 29-403 /37-580} 38-581 4:45 18 Average of 29-639|46-955 529-628 | 44-026} 46-095 | 33-45 169 the year. | ANNUAL RESULTS. MORNING. Burometer. Thermometer. Observations. . Wind. Wind. Highest, 10th Nov. W. 30°53 1ith August, SW... . 63° Lowest, 30th Dec. W. 28°40 5th February. NW. . . 26° EVENING. Highest, 10th Nov. SE. 30°53 1ith August, SW.. . . 64° Lowest, 29th Dec. W. 28°43 5th February, NW. . . 17° Weather. Days. -. Wind. Times, ai oho Metric hie ett at) (169 Nand NE es =i) siue 4 RainorSnow , .. . 196 SaAnGiS Pics: Me oe), oy ai ie 122 — Shands Wen s . ‘ spnory qua “eg PH IAS OPOsScs =] S = f Hie HI YQ avapo V aaasaHa aoc | 19 a ‘ re) nq = [2EVZ5ageeane| ¥ 3 | ‘smensopnung aegean cease =} & SS] . Cl | 3| mmm |-eerasssas ! mcd Ha = SOM [OHO GA trie | © 19 i 2 o He 489 AA “YNOG | CLI HID O DF x19 10D 91 Scale of the Winds. . Eats) qyynog HAO eee Bs a “yseqT-yynog JooSmona accion | a pe) Mew Sy SE Sh o seq Jona tte oon ton a a HARA Le olen ial aseq-yuon [ASSAM BHO | | ive) . - Ie . yon [aowean™ aac | ey : a F ee berate g ere sn Weniehnths eh aks mes? pe RA he eto | ood ge5 cr -SESEE a SRSM vo, BRED | ES Bas RPS eWe sea Cia BOS a8 SB BRS CoOl > SHASASEAAOAZR |S , 3 5 Meteorological Summary for 1823.—Hampshire. 155 ANNUAL RESULTS FOR 1823. Barometer. Inches. Greatest pressure of atmosphere, Noy. 11th. Wind E. 30:600 Least ditto ditto Feb. 2d. Wind N.E.- 28-520 Range of the mercury . . 2-080 Annual mean pressure of the atmosphere sess 29°831 Mean pressure for 181 days, with the moon in North declination . . £9°887 Mean pressure for 204 days with the moon in "South declination . . brains ato) O Annual mean pressure at 8 o'clock A. M. 2» « 29°828 at 2 o’clock P.M. a Mote #0 292899 at 8 o’clock P.M.. Mes 291852 Greatest range of the mer cury in October bees) Oeden S740 Least range of ditto in July erase AOSD Greatest annual variation in 24 hours in December 0:990 Least of the greatest variations in 24 hours in May 0°360 Aggregate of the spaces described by the alternate rising and falling of the ee di Ae Cs wEGBO Number of changes . . . . rite Ree ora Bode Self-registering Day and Night Thermometer. Greatest thermometrical heat, June lst. Wind S. . 76° a cold, Jan. 19th. Wind E. 18 Range of the thermometer between-the extremes . 58 Annual mean temperature of the external air . . 50°54 — of do. at 8 A.M. LW TE RO*'79 of do. at 8 P.M. - + 50°06 2 of do. at 2 P.M. oer 27 Greatest range in January and June . . . . . 84.00 Least of the monthly sisies in Febr uary Et at sek OO Annual mean range : 27°40 Greatest monthly variation in 24 hours in May and ame. > at. a tats 24°00 Least of the greatest He SEE 8 in 24 none in Fe- bruary and September .. . 17:00 Annual mean temperature of spring — a 8 A. M. 50°47 De Luc’s Whalebone Hygrometer. Degrees. Greatest humidity of the atmosphere on the 27th Jan. 97 Greatest dryness of ditto on the 17th June . . . 3) Range of the index between the extremes “yen 66 Annual mean of the hygrometer at 8 o’clock A. M. 66'6 —_— at 8 o’clock P.M. 69°6 at 2 o'clock P.M. 59:1 at 8, 2,& 8o’clock 65°1 U2 _ Greatest June .. By, NO ORI e id Rae Position of the Winds. °. Days. From North to North-East. . . . . . 27% North} 78 Atmospheric Phenomena. No. Anthelia, or mock-suns diametrically opposite - to the true sun ; Sr cane Ree hate. Parhelia, or mock suns on the sides of the tine srints 5 fC are ee Oe eG Paraselenze, or mock-Moons . . . . + + 5 Solar. Tratias 0008 0. tots 2 itera tr oe pote wie ae Lamar babies iz.) . 4 peters. oS ; FoainbOws, SOL’ sant TUGAE. os. hw. s,s. cee cium i Meteors of various sizes . . +. ..- = © | Lightning, days on which it happened . . 14 Thunder, ditto ditto erst apr os Evaporation. Inches. ; . Greatest monthly quantityin May . . . 3°80 156 Meteorological Summary for 1823.—Hampshire. Greatest mean monthly humidity of the atmosphere in February .. - er ee are ek Greatest mean monthly dryness of the atmosphere in : ¢ Meteorological Summary for 1823.—Hampshire. 157 Least monthly quantity in January . . . 0°63 In. Total amount for the year ee er 5 eae IS : Rain. Inches. Greatest monthly quantity in October . 4°820 Least monthly quantityin May. . . . 1125 Total amount for the year near the ground 34-665 Total amount for the year 23 feet high . 31165 N. B. The barometer is hung up in the observatory 50 feet above low-water mark ; and the self-registering horizontal day and night thermometer, and De Luc’s whalebone hygrometer, are placed in open-worked cases, in a northern aspect, out of the rays of the sun,’ ten feet above the garden ground. ‘The pluviameter and evaporator have respectively the same square area: the former is emptied every morning at 8 o'clock after rain, into a cylindrical glass gauge accurately graduated to ;i,th of an inch; and the quantity lost by evaporation from the latter is ascertained at least every third day, and some- times oftener, when great evaporations happen, by means of a high temperature and dry northerly or easterly winds. BaromMeEtricaL PressureE.—The maximum pressure was not so high by ;4,th of an inch this year, as it was in the ge- nial year 1822; the minimum was nearly ;*;ths of an inch less, and the mean 0°103 inch less. The mean pressure for the present year corresponds very nearly with that for 1816. The aggregate of the spaces the mercury has described in its al- ternate rising and falling, is 10°58 inches greater; yet the number of changes is 18 less.than that of last year. For 181 days in which the moon ranged in North declination, the mean pressure was ;47~ths of an inch higher than that in the 204 days she ranged in South declination. TemMPERATURE.—The annual mean temperature of the ex- ternal air a few feet from the ground, is nearly 34 degrees less than that of the preceding year, and less than it has been since the year 1820: but it corresponds exactly with the annual mean temperature for the years 1817 and 1819. It is a remarkable circumstance in the temperature of the air, when the maximum height for the year does not exceed summer heat, or 76 degrees, which was the case this year; and, what is equally as remarkable, it happened on the first day of June. Even the cold and wet year 1816 produced a maximum tem- perature of 78 degrees, which also happened in June. The annual maximum temperature of the air has occurred in June five years out of the last nine, viz. in 1816, 1817, 1820, 1822, and 1823. The annual mean temperature, and the mean at half-past 8 o’clock A.M. this year, correspond within three quarters of a degree ; 158 Meteorological Summary for 1823.—Hampshire. a degree; and the mean at 8 A.M. and 8 P.M. within a quar- ter of a degree. The annual mean temperature of spring water, as taken at 8 o’clock A.M., coincides with the annual mean temperature of the external air within ;7,ths of a degree. The difference between the mean temperature of the air and that of spring water for the last three years does not amount to three quar- ters of a degree; which serves to point out the analogy there is between i mean temperature of the air and that of the ground. The mean state of the air by De Luc’s whalebone hygro- meter, this and the preceding year, coincides within ;4,th of a degree. Winv.—In comparing the scales of the prevailing winds for 1822 and 1823, there will be found a remarkable coinci- dence, the greatest difference in point of numbers, from the eight divisions of the compass, being only 94 days, which was minus in the south-east wind. The south-west wind, which frequently comes across the Atlantic Ocean, has been more prevalent this year than for the last nine years, and the most prevalent for the three preceding years. The following is the number of strong gales of wind, or days on which they have prevailed this year, viz. N. INE, E. [sz S. is. w] W. 'N.W,Days ‘ei[ulafelslele| Hence it appears that the south-west wind here, is not only the most prevailing in light breezes, but in brisk and strong gales ; which is also generally observed at sea. Croups.—Of these the cirrostratus was the most prevalent, and the cirrus, from which it is produced, the next: but it is impossible that we can always perceive the cirrus in its descent, before it is transformed into cirrostratus ; because, ‘in the ab- sence of the sun, or when it is under the horizon, the cirri quickly descend, and put on the appearance of linear cirro- strati. The cirrose crowns of nimi are not noticed here, but are included in the latter modification. In a series of years the cirrus and nimbus are pretty equal in the numbers of their appearance, or days on which they have prevailed. Weatuer.—The difference in the cloudless and fair days this year and last, is 31 days; and the difference in the over- cast and rainy, is 30 days: both in favour of 1822. ATMOSPHERIC PH#NOMENA.—Nothing peculiar in the ap- pearance ee —EEEEEEEEEEeEeEeEe Meteorological Summary for 1823.—Hampshire. 159 pearance of atmospheric and meteoric phenomena has been observed here this year, except a FIERY METEOR of an extra- ordinary size, which appeared about 20 minutes past 6 o’clock in the evening of the 26th of January. The extent of its sudden light, and of its fiery train, was terrific, from which proceeded some degree of warmth while passing over this neighbourhood in a westerly direction. This meteor was seen nearly at the same time by some of the inhabitants of the Isle of Wight, Southampton, Salisbury, Blandford, Dorchester, and other places to the westward. “The air was frosty, and the sky mostly overcast ; and much rain fell on the following day. On the 5th of February, at mid-day, a large semi-halo, 45° from the sun’s centre, appeared over the sun, accompa- nied by a concentric semi-halo of the usual extent, from which it is probable the large one was formed by reflection. The colours of both were conspicuous in an attenuated cirrostratus cloud. The most perfect of the anthelia appeared at 1 P. M. on the 25th of June, in the side of a slow-passing cumulostratus, or compound cloud ; it was 90° from the sun’s centre, within a few minutes, and in an opposite direction to that luminary ; and considering it was the zmago solis, it showed but a mild silvery light, which occasionally contracted its circular shape, and expanded into a. long and irregular diameter, arising from the slow motion and uneven surface of the cloud from which it was reflected. The sun’s altitude then, was about 59°, consequently the height of the anthelion was 31° nearly. The rain is rather more than an inch in depth this year than it was last. The evaporation this year is nearly one-third less than the quantity of rain at the ground; but last year it was upwards of one-fourth more than the rain, on account of the copious falls in the summer months, and the high unprece- dented mean temperature: and it is from this latter circum- stance that we have been more minute in our meteorological comparisons of the last two years. DAMP DETECTOR. An useful application of hygrometry to the purposes of “a housewifery and the preservation of health has lately een offered to the public, in Essex’s Portable Damp De- tector, a small and neat instrument for ascertaining the hu- midity of the atmosphere, and for enabling travellers to detect the damp in beds and linen. L9-62 i -CLIZL-GV 61-17) 28-60 | *Sosvisay kpnojp 9] kpnorg PL-62 £8-60 : 6r | 6€ |PL-6z Apnojp| + Apnor9 8f| 06-62 | $6.62 ! OF | 89-62 Apnojp| Apnoyp 98-62 | €0-0€ ale IP | 88-62 Ast} Apoyo ( 08-62 | 96-62 . 6L-6% urey} §Apnoyp 0. 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WV *YD0[D 0 Iysry ysvd-jyey ye (c, A, B), C the form of the function being the same in all triangles. But. the angle C is a determinate ratio, or a value independent of all arbitrary measurement; and, since the measure of the line bg) c is 164 On the Application of algebraic Functions c is arbitrary, it follows, from the law of homogeneity, that the line cannot enter into the expression of the angle. Wherefore the equation must simply be, : C = 9(A, B). And this proves that the angle C is determined by the other two angles independently of the sides of the triangle. In this investigation triangles that have the same angles at their bases are compared together; and the existence of such triangles is therefore assumed. It is not difficult, it may be argued, to admit that the base of a triangle may vary, while the angles at the base remain the same; and when this is granted, the functional demon- strations are not liable to objection. But the present question relates solely to what is consonant to the principles of geome- try; and that science does not permit the gratuitous assump- tion of related figures. You may draw one triangle, for in- stance that upon the base c; and you may assume as many bases c’, c’, &c. as you please; but you cannot be allowed to suppose that, upon these bases, triangles exist which have two angles in common with that already drawn. In this manner we might be led to reason about figures that have no existence; an absurdity which is guarded against in geometry by the postulates*. You have all the data necessary for con- structing the figures about which you are to reason; and you must construct them by the admitted postulates, without the help of Euclid’s 12th axiom, which you propose to prove. But the triangles cannot be so constructed; and therefore the functional demonstrations cannot be held good in geometry. The difficulty about parallel lines lies in the strictness of geometrical principles. The least relaxation of these would open a door to innumerable solutions. If the analyst, by a latent assumption, evade any of the rules imposed on the geo- meter, the different results of the two modes of investigation can occasion little surprise. Without objecting to Legendre’s mode of reasoning, we have endeavoured to show that his analytical demonstrations cannot be applied in geometry, unless it be assumed, that the base of a triangle. may vary while the angles at the base re- main the same; a proposition which is deducible from Euclid’s * In the Greek geometry the postulates are not to be considered as having a reference to practice. They are theoretical principles precluding the geometer from introducing arbitrary figures and constructions in the course of his reasoning. Legendre does not enumerate the postulates. And even Professor Leslie has degraded from its place, and thrown into the shade, this important and essential part of the geometry of Euclid. 12th lo prove the Properties of parallel Lines. 165 12th axiom. But we may also object to the soundness of his reasoning. : Since the symbols A, B, C denote ratios, by the law of homogeneity, there cannot be an equation between them and the single line c; for, on account of the arbitrary measure of c, such equation would have no fixed or determinate meaning. Therefore the equation C= a) (¢ A, B) is absurd. But from an absurd equation, or rather from no equation at all, you cannot, in a legitimate manner, infer that another equation is true, viz. C= $(A, B). A process of reasoning ought to be stopped whenever the re- lation between the magnitudes concerned implies contradiction, or can no longer be clearly understood. It seems to be an odd argument to infer that there must be an equation in one form, merely because there cannot possibly be an equation in another form. ‘The proper conclusion seems to be, that, in analysis as well as in geometry, there is, in the present in- stance, a peculiar difficulty, or a failing and breaking off in the usual train of investigation. Professor Leslie has attacked Legendre’s demonstrations on other grounds. He objects to the law of homogeneity : but, in a case so very clear and undeniable, his arguments have no weight. He contends likewise that the measure of an angle estimated by its proportion to a right angle is just as arbitrary as the measure of a line in yards. This is more specious. It is urged with great confidence, and clothed, as usual, with the imposing garb of philosophical accuracy. Perhaps Legendre and his supporters have not furnished the proper answer to it. But there are few mathematicians who would oppose the opinion of that eminent geometer on a point of the modern analysis, without great diffidence; and some reflection will show that the functional equations may be vin- dicated from the charge brought against them by the learned Professor. Conceive that A, B, C, instead of denoting angles simply, are the arcs subtending the angles in a circle of which the radius is r; and let Q be the quadrant of the same circle; A B Q? Q” les, are ratios, or quantities of no dimensions, that remain the same in all circles, and however the ares are measured or compared. Now we can obtain equations between the Cc 4 then S? which are no other than Legendre’s an- sides of the triangle and the trigonometrical quantities ns cos 166 On the Application of algebraic Functions -cos A sin B ‘ Bat a sree &c.; and if we suppose that the same quantities ; are changed into the equivalent values expressed in terms of A B © ; 5 9 &c.; we shall obtain the functional equations of Le- (a2 gendre, between the sides of the triangle and the angular ie A B quantities —-, ae a It must be acknowledged, however, that this is some abatement in the simplicity of the equations. Yet it seems difficult to conceive any other way in which the ratios of the angles of a triangle to a right angle, can find their way into the same equations with the length of the sides. It deserves to be particularly noticed that there is no trigonome- trical equation corresponding to the case C = $(c, A, B), which is a mere symbol without meaning, or rather an absur- dity, marking an impossibility in the course of investigation pursued, and from which no certain conclusion can be drawn. But it may be questioned whether, in sound philosophy, the algebraic analysis can be applied to investigate a really funda- mental principle in any science. Analysis treats of number, and of measured magnitude, and of these alone. Some pre- vious discussion founded on the peculiar nature of the mag- nitudes we have to consider, seems therefore to be necessary ; their elementary properties must be explored at least to a certain extent; in order to enable us to compare and measure them, without which they cannot be brought within the scope of analysis. The excellence of the modern method of mathe- matical investigation consists in reducing the first principles in every case to the least number possible, not in dispensing with any one that is essential. ‘This may be illustrated by referring to what so often happens in physical science. When observation and experiment have failed in discovering suffi- cient data, the analyst has recourse to the most probable hy- potheses for obtaining the requisite number of equations. We are not now to discuss the proper use of such hypothetical in- vestigations in promoting physical knowledge; our intention is merely to show that without sufficient data analysis is a use- less instrument. Fundamental principles there must be, either legitimately obtained, or assumed hypothetically, or mixed up in a latent manner in the process of investigation. Whether there be any general character that distinguishes the principles inherent in the nature of things, which we should in vain en- deavour to deduce from a foreign source; and whether the difficulty about parallel lines in geometry do not belong to that class; are points which we do not undertake to settle. The ; to prove the Properties of parallel Lines. 167 The modern analysis, from the universality of its application, has the supremacy of the mathematical sciences. It is the most powerful instrument of investigation that has yet been invented. But this potent engine cannot put forth its strength, until a proper fulcrum has been prepared for it. Professor Leslie has himself attempted to improve the theory of parallel lines, and we shall add a few observations on his manner of treating this difficult subject. His definition is most faulty, involving the idea of infinity. For what notion can we haye of two lines with no mutual inclination, except we conceive that they make at first a small angle which de- creases to zero. But the definition is set down only pro Jorma, and may be blotted out without being missed, since it is doubtful whether it be once referred to in the whole treatise. In reality we are left to gather the sense we must affix to pa- rallel lines from the descriptive and illustrative writing in Prop, 22. book Ist; for demonstration it cannot be called. All this may be very elegant, but it is not in the spirit of the Greek geometry. It is directly opposed to the example of Euclid, who has taken so much pains to avoid whatever is vague, and to exhibit every point to the understanding of his readers in a definite form. But the learned Professor has not been successful in removing any difficulty, or in throwing light upon any obscure subject, in elementary science. If new proofs of this were wanting, we might refer to the manner in which he has treated the composition of forces; the perma- nent axes of rotation; and other matters, in his late volume on Natural Philosophy. Legendre complains that a part of a private letter of his to the learned Professor was published without leave asked and obtained. But the anonymous correspondent who has been dragged before the public in so notable a manner in this dis- pute, has a much more grievous cause of complaint. His opinion with respect to these demonstrations, communicated in_a private letter, was partially published without his know- ledge: the part of his letter which seemed to corroborate the opinion of the Professor being laid before the public, while no notice was taken of another part which coincided with the opinion of Legendre and was opposed to that of the Pro- fessor. March 3, 1824. Dis-1oTa. XXTX. Z£x- [ 168 | X XIX. Experiments on the Adhesion of Nails. By B. Bevan, Esq. To the Editors of the Philosophical Magazine and Journal. Leighton Bussard. AILS of various kinds have been used for many cen- turies, in almost every part of the world, and constitute one of the most general modes of fastening substances together. Every carpenter is familiar with the use of the nail, and pos- sesses a practical knowledge, more or léss accurate, of the force of adhesion of different nails and in different substances, so as to decide without difficulty, what number, and of what length, may be sufficient to fasten together substances of va- rious shapes, and subject to various strains. But so far as my inquiries have been made, I have not been able to find any authentic experiments, of the real force of adhesion of different nails, when driven into wood of different species ; or to learn the actual weight, without impulse, necessary to force a nail a given depth into wood, and also the proper force re- quired to extract the same when so driven. With a view to obtain some useful knowledge upon this elementary mechani- cal question, I had a machine constructed to measure the force of pressure and tension with extensive power, and ap- plied it to the extraction of nails of different lengths, from a quarter of an inch to two and half inches. - Theoretical investigation points out an equality of resist- ance to the entrance and extraction of a nail, supposing the thickness to be invariable; but as the general shape of nails is tapering towards the points, the resistance to entrance becomes of necessity greater than that of extraction:—in some of my experiments I have found the ratio to be about 6 to 5. The following abstract will exhibit the relative adhesion of nails of various kinds, when forced into dry Christiana deal, at right angles to the grain of the wood. Number to} [aches Inches Pounds the pound long forced into |required to avoirdup. ; the wood. | extract. Fine sprigs ...... | 4560 0°44 0°40 DO io wees abenctaen 3200 0°53 0°44 Threepenny brads 618 1°25 0°50 Cast-iron nails... 380 1:00 0°50 Sixpenny nails... ao 2°50 Dittos, ceszastsasse aeeese Ditto, . sencaneesaes sautens 139 Fivepenny....s0«. The Mr. B. Bevan on the Adhesion of Nails. 169 The percussive force required to drive the common six- penny nail to the depth of one inch and half into dry Chris- tiana deal, with a cast-iron weight of 6°275 lbs., was four blows or strokes falling freely, the space of 12 inches; and the steady pressure to produce the same effect, I found to be 400 lbs. A sixpenny nail, driven into dry elm to the depth of one inch across the grain, required a pressure of 327 lbs. to ex- tract; and the same nail, driven endways or longitudinally into the same wood, required a force of 257 lbs. to extract. The same nail driven two inches endways, into dry Chris- tiana deal, was drawn by a force of 257 lbs.;—to draw out one inch, under like circumstances, took 87 lbs. only. The rela- tive adhesion, therefore, in the same wood, when driven trans- versely and longitudinally, is 100 to 78, or about 4 to 3 in dry elm; and 100 to 46, or about 2 to 1, in deal. The rela- tive adhesion under like circumstances to elm and deal is found to be about 2 or 3 to 1. The progressive depths of a sixpenny nail into dry Chris- tiana deal by simple pressure, were as follows: One quarter of an inch a pressure of . 24 Ibs. Pa ARTIC y oe i biss sulicynt sth io sem. ta sts A PE MAC cere erlitice: thod -agitaseeneise Gore PSS One and half inch . . . .. . . 400 DwWO MGRES p55) Sipe Kyle nostiswaerpeLo I may observe, that in the above experiments great care was taken to apply the weights steadily, and that towards the conclusion of each experiment the additions did not exceed 10 lbs. at one time, with a moderate interval between, gene- rally about one minute, sometimes 10 or 20 minutes. In other species of wood, the requisite force to extract the nail was different. Thus, to extract a common sixpenny nail from a depth of one inch Out of dry oak, required . . . . . . 507/bs. day beeed., isis: < 6\¢ ferrcspeeaey ea! syhtein G60 green sycamore . . . . -. . . 312 A common screw of 1-5th of an inch diameter, I have found to have an adhesion about three times that of a six- penny nail. From these experiments I am able to infer, that a common sixpenny nail, driven two inches into dry oak, would require a force of more than half a ton to extract by steady pressure ! I am, gentlemen, yours &c. &c. B. Bevan. Vol. 63. No. $11. March 1824. Y XXX. Papers hi. 170 vg XXX. Papers relating to the Earthquake which occurred in India in 1819. (Concluded from p. 119.] Extracts from Letters of Captain BALLANTYNE, Agent in Katti- war, for his H.S. the Guicwar, concerning the Earthquake. Letter addressed: to Lieut.-col. BARcLAyY. Jooria, June 17, 1819. W E have had a complete earthquake since yesterday even- ing at half past seven o’clock. The shocks have been numerous and severe, and the tremulous sensation does not yet cease. The whole town is literally a ruin: the works are shaken from the foundation, and in many places thrown down. The old tower, which I had given up to Dr. Roy, is a complete ruin: the roof falling in, crushed all his things, and it is al- most miraculous that we happened to be out. My sitting bungalow and sleeping apartments are one shattered ruin. The Dewanjee has quitted the town, and lives outside, it being really not safe remaining in buildings so much injured as those here are. Letter addressed to Mr. WILLIAMs. Jooria, June 18, 1819. YESTERDAY morning we went out to the westward of the town to see some rents which had been caused by the earth- quake in the fields there. The earth separating, had in some places emitted water and fire. On examining the different rents, we found them to be of various extent, from an inch to a foot in breadth; the depth however in all of. them was con- siderable, being to 10, 15, and 20 feet. In some places a black sandy and gravelly soil had been thrown out; in others, a black wet earth. The shocks during the night of the 16th were frequent, but not very severe, and the tremulous motion of the earth scarcely ceased. On the morning of the 17th the weather was close, and the tremulous motion continued in a very sensible and disagree- able degree: about 10 A.M. a distinct and severe shock was felt, but it did not last long. We have had no rain, thunder, or lightning, for these six or eight days. The thermometer has ranged from 86 to 90 and 92 degrees. We had remarked on the 18th that the thermometer had risen two degrees. The dreadful noise accompanying the earthquake was of a rumbling Pen + Papers relating to the Earthquake in India in 1819. 171 rumbling kind, and resembled sometimes that produced by the quick motion of wheeled carriages, and sometimes of a distant cannonade. It is now between five and six o’clock (morning of the 18th): I have felt the motion frequently during the night, and am anxious as to what may yet happen. The morning is close, and appearances unfavourable. My table and chair are at this moment shaking under me. We have already had accounts of this earthquake’s having been severely felt and committing great havoc at Nowanuggur, Zoona-bunder, Moorvee, Tunkaria, Dhewrole, Amrun, &c.; at the last place much of the fort has been thrown down, and eight or ten persons have been killed, besides many horses and cattle. P.S. June 19th, another considerable shock has been felt ; the weather is unusually hot, and appearances unfavourable. To GrorceE Ocitvy, Esg. Secretary to the Medical Board, Bombay. Sir,—I have the honour to report, for the information of the Medical Board, all the circumstances which have come to my knowledge regarding the earthquake which took place in Cutch on the 16th instant; and which, if we take into consi- deration the severity of the shock, and the damage sustained within the range of its operation, has seldom been equalled in modern times. This subject, I am aware, is but little con- nected with medical science; but as forming by far the most interesting and awful part of the natural history of the globe, I have no doubt every thing relating to it will be acceptable to the Board. Different from what has generally been observed in the greater number of severe earthquakes, nothing in this pre- viously occurred, in the state of the atmosphere or otherwise, to indicate the probability of any unusual phenomenon taking place. The months of March and April were extremely hot and oppressive; but during May the weather became milder, and remained much the same as it generally is in that month. About the second or third of June, at night, there was a se- vere squall of thunder and rain, which lasted for about an hour and ahalf. After this the temperature of the air became mild and agreeable; and till the very moment that the earth- quake took place, nothing could be observed to indicate even the smallest change in the weather, far less the approach of such a dreadful convulsion. The first and great shock took place a few minutes before seven o'clock in the evening of the 16th, and the general 2 opinion 172 Papers relating to the Earthquake opinion is that it lasted nearly two minutes. ‘The motion of the earth during this period was most awful and alarming, giving to most people the feeling as if it was about to open and swallow every thing up. In this short space the town of Bhooj, nearly three miles in circumference, became almost a heap of ruins; most of the houses were thrown down, and the greater part of the ramparts and towers, with the guns, were precipitated into the ditch. Nothing was seen by those at a distance but a thick cloud of dust. ‘The same occurred in a greater or less degree in every town and fort from the eastern extremity of Wagur to Luckput on the Indus; and even the smallest villages have been levelled with the ground. The shock appeared to increase in violence as it continued, and suddenly to stop, leaving a kind of tremour ; some people said it was preceded by a noise like thunder or the rattling of a number of carriages, but this was not generally observed. Difference of opinion also exists as to the kind of motion that took place; some people considering it was undulatory, others as a kind of tremour, and others again as coming directly upwards. ‘The last kind of motion appeared to me very evi- dent, though being at the time surrounded by houses and walls falling in every direction, I might not be so well able to judge. I felt as if the force was acting directly where I stood, and as if the earth was making an effort to burst immediately under my feet. People appear to differ as much as to the quarter from which the shock came; nor is it to be ascer- tained from any general direction in which the walls of the towns or houses have fallen: they appear to have tumbled in every direction indiscriminately, and frequently one half of the same wall has fallen on one side and the other half on the other. As far as I have been able to ascertain, in no place has the surface of the earth suffered any important alteration from the shock. There are reports of fire having issued from hills to the westward of Bhooj, but I do not think they will be found correct. On the 17th I travelled between Bhooj and Anjar, a distance of twenty-seven miles, and part of the road through hills; and though I looked carefully in every direction, I could perceive no recent changes. In the bunds of tanks and the steep banks of ravines, small rents could be perceived: in the hard rocky soil, which forms the general surface of the coun- try, no alteration was to be seen. After the shock several dry rivers became filled with water, which afterwards gradually subsided. About Anjar the water in the wells became of a milky colour, but was not altered in taste. With respect to the places affected by the shock, Anjar and which occurred in India in 1819. 173 and Bhooj appear to have suffered much more than any other I have yet heard of; in the former nearly 200 dead bodies have been dug out of the ruins, and in the latter 1000 are sup- posed to have perished, besides numbers in both towns miser- ably maimed. It would be impossible even to guess at the number of victims throughout the country: it will be sufficient to remark that not only in large towns the fatal effects of the shock have been felt, but even in the smallest villages — some lives have been lost. In Anjar the effects of the shock appear to have been greatly modified by difference of situa- tion; the quarter of the town towards the east, and which is the lowest, has been reduced to one mass of ruins. Neither street nor lane is to be discovered, and literally there is not one stone remaining on the top of another: the town wall on this side has suffered in an equal degree. The other part of the town, with the wall, though dreadfully shattered, does not appear to have suffered one tenth part of the injury. This must be accounted for from the lower part being situated at a considerable distance from the rock, upon a bed of white aluminous earth, while in the higher part the foundations of the houses are situated immediately upon the rock. It could not be owing to the shock being more severe in that particular place, as, extending over such a considerable tract of country, its force could not have differed in such a small space. Since the 16th constant shocks have been felt, perhaps all together nearly thirty in number. The weather continues much the same as might be expected at this season. ‘The wind is very variable: heavy squalls are suddenly succeeded by dead calms. The atmosphere is cloudy, with a hazy horizon. There is nothing peculiar in the appearance of the sun at rising or setting; only one meteor (a ball of fire) has been ob- served since the occurrence of the earthquake, and that was on the night on which the first shock took place. I have to apologize for the unconnected manner in which the above account is detailed; but the mind cannot be quite at ease in the midst of so much desolation, and while the awful phznomenon that produced it is still in some degree im- pending. Should any thing additional worth reporting come to my knowledge, I shall immediately communicate it to the Board. I have the honour tv be, sir, Your most obedient humble servant, (Signed) James M‘Apam, Anjar, 29th June 1819. Assistant-Surgeon. P.S. I had no opportunity of forwarding the above letter till to-day. Shocks still continue to be felt, and there was a very smart one yesterday evening. The earthquake appears to 174 Papers relating to the Earthquake to have been felt all over Kattiwar, and as far east as Kaira and Baroda; also at Radhunpoor, and I believe in Sind. Cutch, from all accounts, appears to have been the centre of its operations, and especially the western part of it. Moondra and Mandavi, two large towns on the sea-coast, have suffered in comparatively a trifling degree; but the inland towns and forts towards the Indus have been almost completely de- stroyed. There has been a heavy fall of rain at this place, and the weather continues cool and pleasant. (True copy) (Signed) GrorcE Ocitvy, Sec. Medical Board. Copy of a Letter from Captain Evwoop. Poorbunder, June 7, 1819. WE yesterday evening experienced in this fort and city one of the most awful scenes in nature, that of a violent and de- structive shock from an earthquake. The weather was close and sultry: the thermometer ranged at 86° at sunset, and a light air, scarcely perceptible, was sometimes felt from the southward. An officer and myself were taking an evening walk on the ramparts of the fort, and had gone nearly all round, when, at 40 minutes past six, we observed to each other how excessively close and oppressive the atmosphere was; and five miuntes after, I heard a distant sound not unlike that of a cannonade at sea. A thought had scarcely passed the mind as to what could give rise to the sound, when I felt a violent shock beneath my feet, and in- stantly exclaimed, “* An earthquake!” Looking at the same time forwards, I saw the stone parapet at two yards distance violently agitated by a quick, short, wave-like motion, bend- ing in and out with the greatest pliability, and with the vibra- tion of about a foot, and attended with an incessant hissing cracking noise. I thought it impossible that the works could stand, and, expecting their immediate fall, I instantly deter- mined on descending as quickly as possible; but as the ram- part was a perpendicular height of masonry of about 20 feet, I was obliged to run back towards the nearest ramp, which was a flight of stone steps at some distance. The officer I was walking with followed; and as we passed along at a quick rate, the sensation felt was similar to that dangerous and dis- agreeable one of running along an elevated and elastic plank, the ends alone of which are supported. I every instant ex- pected to fall with the works, or to be precipitated from them ; but, reaching the steps, ran down as fast as I could, each lower step apparently meeting the descending foot kgs reanly which occurred in India in 1819. 175 really believe was the case, as the whole flight of steps was violently agitated). While passing down, I expected to be overwhelmed by the works, which were touching my right shoulder, and above my head. | Although the rampart and parapet are about twelve feet thick, and twenty-five feet in height, yet this wall of masonry waved to and fro. Fortunately the steps were broad; had they been narrow, as is frequently the case, so great was their agitation that it is doubtful if we should have got down without being thrown over the side. Arrived at the bottom of the ramp, we did not cease running until we had got to a sufficient distance from the works to prevent their falling on us. On halting, we were surprised to find that the works had not fallen after so extraordinary an undulating motion. On reaching a place of comparative safety, for there was no place absolutely safe, the attention was attracted by a vast cloud of black dust arising at about three hundred yards di- stance, and from the sea face of the fort, which ran at right angles with the one we had quitted. The danger being past, my curiosity became excited; and approaching the cloud of dust, I found it to be occasioned by the fall of towers and of large portions cf the curtain, leaving several breaches, some forty and some sixty yards wide. This devastation extended for five hundred yards, and over a part of the fort which I had been walking on not five minutes before. I do not imagine that a twenty-four hours’ fire from ten pieces of heavy ordnance could have produced so extensive a destruction as was thus effected in the space of a minute and a half. We conjectured that the awful shock had not lasted more than that short period. Short as it was, it was powerful enough to destroy the work of ages. We now directed our attention towards home, and the first occurrence that was met with near it, was the horse-keepers with the horses in their hands standing in the open air; hay- ing been apprehensive, as they said, that the stables would have fallen and killed the horses. On entering the house, my servant informed me, that while making my bed in one of the upper apartments he had been thrown down on the floor, and that before he could make his escape he was thrown down a second time. } A gentleman and lady, on hearing all the tiles of their house in motion, and crackling as if in a fire, and observing the whole of their furniture shaking, immediately got down stairs into the open air. The gentleman informed me, that although 176 Papers relating to the Earthquake in India in 1819. although his stairs were broad and built of very solid masonry, such was the agitation they were thrown into by the earth- quake, that he experienced much difficulty in descending. An officer’s house, a very substantial stone building about forty feet high, which stands by itself, appears to have been affected by the shock more than the other houses. The sepoys describe it as having rocked from side to side as a tree in a high wind. On examination, so many rents were found in the walls that it was deemed unadvisable to sleep under its roof. I believe there are few houses throughout this large city which are not more or less injured. Some have fallen so as to block up the streets in which they were situated. The rajah and the principal inhabitants are now encamped outside; which they prefer to trusting themselves in their own houses, the fall of which would prove very destructive, as they are made of a thick terrace supported by stone or weighty timber. The earth opened, and water issued from the cavity, in a plain fourteen miles hence. The atmosphere to-day has been impregnated with a strong smell of sulphur; and between 10 A.M. and 2 P.M. there were several other shocks, which brought down some old houses: but these shocks were not to be compared with yes- terday’s awful phenomenon. It was observed that all animals were much frightened : the dogs lay down on their bellies and would not be moved. The earthquake in the interior appears to have been less violent than near the sea-shore. I am this moment informed that fifty men have been killed’ by the fall of walls at Mangarole, which is distant hence 80 miles in a S.E. direction. Copy of a Letter addressed to Captain KENNEDY. Camp, Sirdas, June 17, 1819. Srr,—Being a Member of the Literary Society, I deem it a kind of duty that attaches to me, to record for the informa- tion of the Society any fact or circumstance of considerable interest which may fall under my observation connected with the objects of the Society. In these sentiments, I now have to mention the occurrence of the shock of an earthquake here yesterday evening. It oc- curred about seven o’clock. It was such as to alarm every one who felt it. The earth under us seemed to rise and fall very considerably; so considerably, indeed, that I myself could not stand steadily. Every one who felt it became in some Mr. F. Baily on the Circular Micrometer. 177 some degree giddy. It was not felt by any one who was on horseback; and this was the case with several of our officers. Every one, however, who was on the ground felt it to be very alarming. The duration of it was not measured by any one, but I think it lasted about two minutes. It was at first slight, and towards its termination the motion became less and less vio- lent. We have had no accounts of it from neighbouring towns; so that I am led to suppose it has not been so violent as to do much mischief in other places. This country, Kattiwar, is rocky and rugged. ‘The rock is of the trap kind, containing great quantities of agate and crystallized quartz. I have observed nothing of a volcanic nature, unless the trap be considered such.—I now have the honour to remain, Sir, your very obedient servant, (Signed) G. A. Sruarz, Assistant Surgeon, Ist Light Cavalry, 1. See ee XXXI. On the Circular Micrometer. By ¥. Batry, Esq. HE circular micrometer is an instrument which has been, for many years past, much used on the continent, and is still held in high and deserved estimation there by astrono- mers of the first rank. From the simplicity of its construc- tion, and the facility with which it may be used 7x any posi- tion of the telescope, it is frequently preferred, even in public and national observatories, to micrometers of a more complex nature, which require to be adjusted to the equatorial motion of the star. Moreover, there is no necessity for its being il- luminated ; on which account it is peculiarly adapted to the observation of comets and small stars: and it is indeed to these two classes of the heavenly bodies, that its application is now principally confined ; although some astronomers of great eminence have considered that it is capable of equal accuracy to the wire micrometers. To voyagers and others, who are travelling for the improvement of astronomy and geography, it will prove of considerable advantage. The smallness of its size (it being not much larger than a shilling) renders it very convenient for carriage; and the simplicity of its construction prevents any liability to injury. On this account it ought to form a part of the apparatus of every person travelling under the circumstances above alluded to. Astronomy is indeed more indebted to this little instru- Vol. 63. No. 311. March 1824, Z ment 178 Mr. F. Baily on the Circular Micrometer. ment than is perhaps generally known. Three out of the four new planets which have been discovered in the present century, were discovered with very small telescopes, and their motions watched, and the elements of their orbits deduced from observations made with the circular micrometer only: whereby astronomers were enabled to look out for them with certainty, at the time of their re-appearance at the next op- positions. And at the present hour it is almost the only in- strument used on the continent for the observation of comets. To the labours of Olbers, Bessel and Frauenhofer, we are indebted for the high reputation which this little instrument enjoys. To the two former, for the talent which they have displayed in explaining the analysis, by which the observa- tions may be reduced: and to the latter for the recent im- provement which he has introduced in the construction of the instrument. In a communication like the present, it cannot be expected that I should enter very minutely into a subject of this kind: my object being merely to draw the attention of practical astronomers in ¢his country to an instrument which appears to be very little known here: but which is capable of doing much useful work at a very little expense; and of assist- ing the observations of those who are fortunately possessed of more splendid and powerful instruments. By the kindness of Professor Schumacher, who is ever zealous in promoting the interests of astronomy, I have ob- tained one of M. Frauenhofer’s circular micrometers, of the most improved and recent construction. This instrument is the same that was exhibited at the last meeting of the Astro- nomical Society of London *; and is called by M. Frauen- hofer the suspended circular micrometer, from the circum- stance of its appearing (in the telescope) as if suspended in the heavens without any support. It consists, in fact, of no- thing more than a circular piece of plate-glass about one inch in diameter, in the centre of which a circular hole is cut, of half an inch in diameter. To the inner edge of this glass circle a narrow ring of steel is firmly and securely fastened ; and, the whole being put in a lathe, the steel ring is turned perfectly circular, and reduced to a very thin edge, both at its exterior and its interior circumference. The glass, with its steel circle, is then burnished into a brass ring or cap, by means of which it may be placed, when required, in the focus of the telescope. The advantages attending this construction are, 1° the preservation of the circular form of the ring, as it comes from the lathe, without the risk of its being injured in attaching it * See the proceenngs of this Socicty, at the end of the present Number of our Journal. to Mr. F. Baily on the Circular Micrometer. 179 to the telescope in the usual manner: 2° in the use of steel instead of brass, whereby a finer edge may be given to the circumferences*: 3° in rejecting the metal arms by which these rings were formerly attached to the sides of the tele- scope, from the unequal expansion of which (or any external violence given thereto) the perfect form of the circle might be injured, without being immediately detected: 4° in thus avoiding the obstructions which those arms might in some cases, by their position, occasion in the observations of the passage of a star before it entered the interior of the ring. In Plate III. fig. 4, I have given a drawing of this micro- meter, on a scale just double its real dimensions: the whole instrument, in fact, not being larger than the broad inner circle there delineated. By means of the outer glass circle, the star can be seen, from the time that it enters the field of view, until it reaches the steel circle; at which time the ob- server must be prepared to make the observation required. But, previous to the application of this instrument to any useful purposes, it will be necessary to determine with ac- curacy the radius of the inner circle (which I shall denote by rv) in the following manner. Let the telescope be turned towards any known star, situated as near to the equator as possible; and as nearly in the direction of the meridian as possible, in order to prevent the errors arising from refrac- tion. In the diagram (fig. 4) I have presumed that the tele- scope inverts; and that the star makes its appearance in the field of the telescope on the right-hand side at Q. If we suppose the path of the star to be along the line QQ’, then will this line be one of the parallels of declination, and the line NS, perpendicular thereto, one of the horary: circles: N being to the north and S to the south. A very few trials will enable the observer to place the telescope in such a man- ner that the star may pass exactly through the centre of the field of the circle. Nalas by the clock, the time of the ingress of the star, from behind the broad circle at O; and also the time of its egress at O’.. Let ¢ denote the former, and ¢ the latter; then will : u—t 15 x—— x cos 0 = Sy be the radius of the ‘nner edge of the broad circle; and will be a constant quantity to be used in all the subsequent com- putations. In this equation I have assumed @ equal to the de- clination of the star observed; which, in this case, is the same as the declination of the centre of the circle. * As steel may be liable to rust, particularly on sea voyages, probably gold would be preferable on such occasions. Z2 When 4 180 Mr. F. Baily on the Circular Micrometer. When an observation.is to be made with this micrometer, let the telescope be directed towards the object (a new planet, a comet, or other small body) which may be made to describe any chord of the inner circle; and note the time of its ingress at p, and its egress at p’: let us represent the former by r, and the latter by 7’. The telescope remaining perfectly steady, note also the ingress and egress of any known star, contiguous thereto, at s and s’: and represent the respective times, as shown by the clock, by 6 and 6’. Then will +¢ +¢ oad and =a be the respective times of the transit of the planet and the known star at 4 and &, or at the horary circle NS. Con- sequently the difference in the right ascension of these two bodies will be Fis laa a apne Spee (A). Q 2 The method of determining the difference of declination is somewhat more complex. It is evident that the semi-chord ph= A115. cos A’: and v—é 4 57715. cos A: A being the de- clination of the known star, and AV the estimated declination of the small planet or comet. Make that the semi-chord sk = : Bip ast 5 sin 2 = —— = —. (6/—8). cos A 7 r h 75 sin a = re = ——.(r’—1). cos A’ then we shall have Ck=r cos x = the dist. of £ from the centre C Ch=r cos x= the dist. of 4 from the centre C whence we obtain the difference of declination dD =r (cos x— cos 2’) (B) These computations are founded on the supposition that the known star and the comet both pass through the circle, on the same side of the centre C: that the known star is si- tuated to the northward of the comet; and that it passes through the circle after the comet. But it is easy to apply the same principles to any other relative position of the bodies observed: since it is only necessary to attend to the signs of the respective quantities. Sufficient has been here stated to point out the general mode of computation in such cases. The reader who is desirous of pursuing this subject more at length Dr. Walchner’s Examination of Hyalosiderite. 181 length may consult the Monatliche Correspondenz by Baron Zach, vol. xvii. xxiv. and xxvi.; where he will find tormule adapted, by M. Bessel, to almost every case that can arise in practice. See also Santini’s Elementi di Astronomia, vol. i. page 261. Although I have, in this communication, alluded only to the immersion and emersion of the bodies with respect to the inner circumference of the ring, yet it is evident that the same principles may be applied to the immersion and emersion of the bodies with respect to the outer circumference of the ring, at ,o, and 7’, o’, respectively. And these double observa- tions will tend to ensure greater accuracy. M. Frauenhofer however considers that the edge of the inner circle is more perfect than that of the outer one. It must be evident that the correctness of any results, de- duced from a micrometer of this kind, will depend on the ac- curacy with which the circles are turned and finished. In this respect M. Frauenhofer’s micrometer seems as perfect as human skill can make it: and it certainly does credit to the talents of this distinguished artist. XXXII. Mineralogicul and Chemical Examination of Hya- losiderite, anew Mineral. By Dr. Wavcunen, of Freiburg in the Breisgau.* (With a Plate of Crystals.) I. Mineralogical Description. 9 izlls HE mineral, of which I now communicate an examina- tion, is found on the Kaiserstuhl in the Breisgau, a rock belonging to the trap formation, in the neighbourhood of the village Sasbach, in a basaitic amygdaloid, of a reddish and liver-brown colour, accompanied with augite and bitter spar. I found it so long ago as the year 1819, when on a minera- logical excursion which I undertook upon this interesting mountain. ‘The opinions concerning it were very various: sometimes it was declared to be olivine, and sometimes it was pronounced to be augite. Both assertions appeared to me im- probable, and I felt inclined to look upon it as a mineral hitherto unknown. A more particular examination of its form and composition strengthened my opinion. At Gottin- gen, where I afterwards continued my studies, I resumed my investigation of the subject, and communicated the re- * From Schweigger’s Neues Journal fiir Chemie, &c, band ix. p. 65. sults 182 Dr. Walchner’s Mineralogical and Chemical sults of it, together with the mineral, to my honoured teacher M. Hausmann; who acknowledged it to be a new mineral, and was so good as to direct my attention to the analogy be- tween it and crystallized iron slag. § 2. Hyalosiderite occurs for the most part in crystals; but like- wise in small blunt-edged, friable, loosely coherent grains. The crystalline forms hitherto observed in it are the following: (1.) The rectangular octahedron, having its terminal solid angles replaced by tangent planes (fig. 1). This form varies, a.) By the different proportions of the terminal planes to those of the octahedron. ‘The former are sometimes so large in proportion to the latter, that the crystallization acquires the appearance of a rectangular four-sided tablet bevelled on each side (fig. 2). b.) By the elongation in either direction of the edges of the base, which is sometimes so considerable, that the form ° becomes prismatic (fig. 3). (2.) The same crystallization (1) with the greater edges of the base replaced by tangent planes, those planes generally small (fig. 4). 3.) The same crystallization (1), with the greater edges of the base replaced by two planes. The size of the new planes varies in proportion to that of the others. They are sometimes small (fig. 5), and sometimes so enlarged that the planes of the octahedron on which they rest almost disappear (fig. 6). ‘ (4.) The same crystallization (1), with the solid angles of the base replaced by two triangular planes, usually very small (fig. 8). (5.) The same crystallization (1), with all the edges of the base replaced by two planes (fig. 7). Twin crystals I have not met with. § 3. The crystals are very small, scarcely of the size of lentils ; they appear when the amygdaloid has become disintegrated, as they resist the action of the elements for a greater length of time; they are either attached to augite, or freely dissemi- nated in the amygdaloid; and are, for the most part, imper- fectly formed. heir surface is smooth, and exhibits, i an oblique light, sometimes a brass yellow, or a gold yellow co- lour, sometimes the colour of tarnished steel; which is owing to a thin coat of perhydrate of iron, investing most of the crystals. Their proper colour is reddish- or yellowish-brown. Fracture Examination of Hyalosiderite, a new Mineral. 183 Fracture small conchoidal; external lustre metallic, of the fracture vitreous; hardness, in newly exposed crystals, be- tween that of felspar and that of apatite ; cleavage at right angles to the axis of the octahedron AA’ (fig. 9), not very perceptible. Transparent on the thin edges, or in small splinters, with a hyacinth red colour passing into a wine-yellow; the streak of a cinnamon colour. Specific gravity 2°875; temp. 70°7 F. Single crystals are sometimes attracted by the magnet; but always after they have been made slightly red hot, by which they are rendered black. Before the blow-pipe they immediately become black and melt into a globule, which is attracted by the magnet. With borax they are readily and completely reduced to a transparent glass, which, while hot, has a yellowish-green co- lour, that almost entirely disappears on cooling if but little of the mineral has been employed; but if the borax be saturated with it, it becomes black and opake. They are dissolved by salt of phosphorus into a clear greenish glass, leaving a skeleton of silica behind, and the glass atter cooling becomes colourless. If the boracic glass, containing a small portion of the mi- neral, be cautiously treated with tin, the globule, after it has become quite cold, exhibits a slight but determined beautiful green colour. § 4 From the nature of the forms above enumerated we may assume, that the system of crystallization of this mineral is a trimetric one *. The planes d and d, presenting themselves most frequently, and which form the rectangular octahedron, appear then as bounding planes, which truncate rectangularly the edges of the base of the ground form; the planes a as the horizontal, and the planes P as the primary planes, since the edges, which those planes form with the planes d’ and d, are in parallelism with each other. § 5. The primary planes are too small for the measurement of their mutual inclination. The inclination of the planes d and d may be determined most exactly, although, on account of the smallness of the crystals, even these measurements remain imperfect. The inclination of d on d’ was determined to be 141°, and the inclination of d’ on.a amounted to rather more than 130°. Now if these measurements are taken as the basis for determining the mathematical character of the primary * Hausmann Unters. iib. d. Form. d. lebl. Nat. i. p. 417. form, 184 - Dr. Walchner’s Mineralogical and Chemical. form (fig. 9), then the following proportion of inclination for the base would pretty nearly approach the truth: BE HO: CA= Wes e 7-10. The inclination of the primary planes on the principal axis, or the angle EAC, would, according to this proportion, be =34° 59’ 38", and the angles of the base B B’ B=111° 10° 6”, and B’ BB’=68° 49’ 54”. § 6. Besides the primary planes, the bounding planes A, B’, D, D’ occur in the crystals hitherto observed, the inclinations of which may be found immediately from the proportion of in- clination on the base. The planes 7’ and 7, on the contrary, are secondary planes, from the second division of the vertical edge-zones. ‘The inclination of the planes r’ which appertain to the first vertical edge-zone, was ascertained with some exactness. They answer to the secondary proportion 2C B’: 3CA; whence the sign B’A2 belongs to them. ‘The planes r probably answer to an analogous secondary proportion in the second vertical edge-zone. : Tf The denotation of the different crystalline forms hitherto observed in this mineral would consequently be, 1.2A. 4D. 4D. (fig. 1, 2, 3.) a d’ d 2.2A.2B’.4D'’. 4D. (fig. 4.) a pera d 3.2A. 4D. 4D. 4B’AZ. (fig. 5, 6.) d 7! 4. 2A. 4D. 4D. 4BA2. 4 BAZ? (fig. 7.) aii d . 5. §P. 2A. 4D’. 4D. (fig. 8.) a d d The chief inclinations are, PonP’=110° 0’ 44” a...d'=130 18 56 a...d =141 4 54 A pth ==, 90) 22 6 @ vas 11 oO Lae WD = 150, 41k ? ..@ =119-.99 47 F ..f =169 10 51 Post =l2l 0,26 8. On a comparison of the crystallization of the hyalosiderite with Examination of Hyalosiderite, a new Mineral. 186 with the crystals of slags, formed in various metallurgic pro- cesses, we find a corresponding similarity not only in the forms in general, but also in the angles of inclination of the planes. The measurement of these angles, which M. Haus- mann has given in his Specimen Crystallographie Metallurgica, § 32, could be but very imperfect on account of their small ‘size. The determinations here communicated, which cannot indeed boast of very great accuracy, will contribute to adjust in some measure the determinations published in that treatise. The rectangular octahedron described by M. Hausmann (fig. 14, 15,16) is formed by the planes which are here marked d and 7’; the planes d answer to the planes M, chosen in the definition of that treatise ; so that the planes 7’ corre- spond with the planes P. Later observations have also ac- quainted us with the planes d’ in the crystallized slag. The rectangular bases of the rectangular octahedrons in the cry- stallized slag, namely in that from the copper pyrites smelting works at Lauten (Hausm. Spec. Cryst. Met. fig. 18), answer perfectly to an octahedron formed by the bounding planes d’ and d. The angles which the diagonals of the rectangular bases form with their edges, are similar to the semi-angles of the base of the ground form, consequently = Z CBB and 4CBB’. These angles measure, according to the funda- mental proportion of inclination above assumed, 55° 35’ 3” and 34° 24’ 57”, II. Chemical Analysis. § 9. The hyalosiderite brought to a red-heat, whether in a glass _ retort or in a platinum crucible, becomes black, but does not yield any perceptible quantity of water; nor is it perceptibly altered in texture or in weight. Concentrated muriatic acid attacks the mineral even when cold, dissolves it by the aid of a gentle heat, and forms with it, On evaporation, a gelatinous mass, which after desiccation was evidently silica. a.) A few decigrammes of the powdered mineral were now treated with concentrated muriatic acid, until their solution was completely effected ; the solution evaporated to dryness by a gentle heat; the residuum extracted by water, acidulated with the same acid, and separated by a filter. The yellowish fluid thus obtained was mixed with caustic ammonia, which produced a reddish-brown precipitate. This was again dis- solved in muriatic acid, in order to ascertain whether mag- Vol. 63. No. 311. March 1824. Aa nesia 186 Dr. Walchner’s Mineralogical and Chemical nesia was present, and the solution was carefully neutralized with carbonate of soda. Perhydrate of iron was separated, which was treated with caustic potassa and then separated by filtration from the alkaline fluid, from which muriate of am- monia precipitated a little alumina. The solution, from which iron and argillaceous earth had thus been separated, was mixed, at a boiling heat, with carbonate of soda. The co- pious precipitate thus obtained consisted of magnesia, which, after desiccation and exposure to a red-heat, and re-solution in dilute nitric acid, yielded a little oxide of manganese. The neutralized solution of magnesia in nitric acid became turbid, but in a scarcely perceptible degree, by the addition of oxalate of ammonia. b.) A second portion of the mineral was treated with muriatic acid, in order to ascertain the alkali which it might contain: the solution was evaporated to dryness, the silica separated in the usual manner, and the fluid remaining after the separation of the silica precipitated with caustic am- monia and with its carbonate. The residuum obtained by evaporation, was ignited in a platinum crucible, in which mu- riate of potassa remained. It will be seen from these experiments that the hyalosiderite consists of silica, oxide of iron, magnesia, alumina, oxide of manganese, and potassa. §10. A. In order to determine the proportions of the constituent parts of this mineral, it was subjected to the following analysis : a.) 1:040 gramm. of hyalosiderite, reduced to the finest pow- der, were exposed to a moderate red-heat for about half an hour in a platinum crucible, with three times its weight of anhydrous carbonate of soda. The mixture, after fusion, was of a brownish-yellow colour, and gave, when softened with water and treated with concentrated muriatic acid, a clear yellow solution. By evaporation to dryness &c. 0°329 of calcined siliceous earth were obtained. ; 6.) After the separation of the silica, the remaining fluid was accurately neutralized with carbonate of soda. The pre- cipitate thereby occasioned, after having been separated from the fluid, was digested, whilst yet in its moist state, with a so- lution of caustic potassa, so long as it became diminished in quantity; and the residual iron well dried and calcined gave 0°330 gramm. of peroxide of iron, =0°309 protoxide of iron. _¢.) ‘The alkaline fluid of (4) was now treated with a solu- tion of muriate of ammonia so long as precipitation took place. This Examination of Hyalosiderite, a new Mineral. 187 This precipitate, after calcination, amounted to 0°023 gramm. and had the properties of pure alumina. d.) The fluid (4), from which the iron and argillaceous earth had been precipitated, and which did not become turbid by the addition of oxalate of potassa,was again acidulated, evapo- rated to the requisite degree, and precipitated at a boiling tem- perature with carbonate of soda. The precipitate dried and strongly calcined gave 0°277 gramm. of magnesia, which, af- ter being dissolved in dilute nitric acid, left 0-005 of oxide of manganese. e.) The magnesia still contained in the remaining fluid of (d), after that had been previously neutralized with muriatic acid, and sufficiently concentrated, was precipitated by means of carbonate of ammonia and phosphate of soda; by which 0°164 gramm. of calcined phosphate of magnesia were ob- tained, which answer to 0:065 gramm of pure magnesia. B. In order to determine the proportion of potassa in the hy- alosiderite, 0°567 gramm. of the mineral were treated with muriatic acid; the iron, alumina, magnesia, silica, and man- ganese, separated in the usual manner, the remaining solution evaporated to dryness, and the residuum calcined in a pla- tinum crucible. What remained was dissolved in distilled wa- ter, and treated with muriate of platinum, and thus gave 0°055 gramm. of the triple salt =0°016 gramm. pure potassa. As the relative effect of glass of borax in the treatment with tin seemed to indicate the presence of chrome in this mineral, a quantity of it, exactly weighed, was fused with nitrate of potassa in order to discover that metal. The melted mass was of a yellowish-brown colour with some grass-green streaks which originated from sub-manganesate of potassa. The so- luble part was now properly extracted with water, the fluid thus obtained carefully neutralized with nitric acid, and then treated with a solution of protonitrate of mercury, on which a slight reddish turbidness merely took place, so that the quantity of chrome could not be ascertained. According to this analysis, 1:040 gramm. of hyalosiderite, yield silica (2) . sosenged 19,9470'329 gramm. Protoxide of iron (6) . . . 0309 imei (0). cies ens are Dittos(2) z.22y 0088 Veo’ bie O0G6S Alumina (c) Ryn. 28) Lt i OOZS Oxide of manganese (d) . . 0°005 FOtMREEs( DO )stol- ile tn di = ot ae Traces of chrome Aa2 1°032 188 Dr. Walchner’s Mineralogical and Chemical: 100 parts of this mineral therefore contain BSUICR). S* \csiscanrd 9 wane ee Beek Protoxide of iron . . . . 29°711 Magnesia. . . . ». « « 32°403 Ablimina, ji vk per. eee ii 2-911 Oxide of manganese . . . 07480 Bienen hts bese ccs oy tosieart ee ae Traces of chrome* 99°227 § 11. Through the kindness of my honoured teachers MM. Haus- mann and Stromeyer of Gottingen, I was enabled to submit to a chemical analysis some slags, the mineralogical similarity of which with our mineral has been mentioned above. The same method was followed in the analysis which was observed. in that of the hyalosiderite, and I therefore briefly state the results. § 12. | An iron slag from the iron smelting works near Dax in the Pyrenees, which M. Hausmann has described}, and which M. Stromeyer kindly presented to me, had the specific gravity of 3°700 at the temperature of 73°4 F. and contained, in 100 parts, Silica . . . . . . 382°959 Protoxide of iron . . 61°235 Magnesia. 1... . 1.896 Alumina) (30 °c) ep 1°560 _ Oxide-of manganese. . . 1°301 PPOtSSSA in Se anacasanreviont? aston 99°155 13% Another iron slag, from Bodenhausen in the Hartz, which in its external appearance bore the greatest resemblance to our mineral, was kindly presented to me by M. Hausmann. Its specific gravity was 3°529 at the temperature of 70°7 F. and it contained, . 1 Siliea sicos. yiesowr « «925846 Protoxide of iron . . 62:042 Magnesia. . . «© = 1°404 Oxide of manganese . 2°645 Potassg, ... §./A% tet) oy olO286 99°746 * My honoured friend Professor Buzengeiger directed my attention to the presence of chrome in this mineral. Chrome has prebably been over- looked in many minerals. On a future opportunity I shall have occasion to point out its existence in a mineral long known and frequently analysed. R Moll’s Ephemerides, d. B. u. H. III. 1815, p. 39, ff A third Examination of Hyatosiderite, a new Mineral. 189° § 14. A third slag, which had been found many years ago at Lautenthal in the Hartz at copper-works where copper pyrites was smelted, and the crystallization of which has been described above (§ 8), I likewise obtained through the kind- ness of M. Hausmann. _ Its specific gravity at the temperature of 65°3 F. was 3°870. As I had convinced myself by a previous analysis, that it contained copper, I directed through the solution in muriatic acid, after the silica had been separated from it, a current of sulphuretted hydrogen gas, treated the precipitate thus ob- tained with nitric acid, and then separated the oxide of cop- per by caustic potassa. The fluid remaining after the separa- tion of the copper; was treated, whilst warm, with nitric acid, and heated for some time, so as to bring the iron to the maxi- mum of oxidation; the analysis was then proceeded with as usual. This slag from Lautenthal contained Silieay(') 1%) SUPalL 2 Sggigig. gs Protoxide of iron . . 63°316 Peroxide of copper. 2646 Magnesia . . .°. = 1*304 Afomaiias..o> ccc eee 1°244 Oxide of manganese . 1-460 Pétassa ©0042 PO rereK 99°399 I consider that mineral as a slag likewise which Karsten has described, and which Klaproth analysed, under the name of volcanic iron-glass*. According to Klaproth’s analysis, 100 parts of it consist of Sili¢ay: vei Peo, oe digg Bg Protoxide of iron . . 66:00 Alanine! 0 2492" VareQ Potassay, stent Sy da! wgagg 99°75 § 16. The crystallized slag is consequently a silicate of iron. This in the hyalosiderite appears to be combined with magnesia, which seems to replace the quantity of iron in the slag. * Beitrage, V.222 ff. Stromeyer in the Gitt gel. Anz. 1810. st. 194. p. 1935. M. Hausmann has given further particulars of it in V. Moll’s Jahrb. d. B. a, H. 1. 1815, p. 39. ff, From 190 Mr. Samuel Seaward on High-pressure Gauges. From the analysis above detailed, it is evident that the mi- neral from the Kaiserstuhl is actually anew one. The name hyalosiderite has been sug ested by its properties and its com- position, and is derived from Jaros glass, and cidygos iron. The formation of this mineral, it is probable, could not have been the result of operations like those by which the primitive rocks were produced ; and we may thence assume, that the rock in which it occurs is of volcanic origin. XXXIII. On High-pressure Gauges. By Mr. SaMvue. SEAWARD. To the Editors of the Philosophical Magazine and Journal. Gentlemen, |= is highly creditable to the taste of your ingenious cor- respondent Mr. H. Russell, that he can extract so much amusement from the manufacturing of high-pressure gauges. I hope no one will be so selfish as to envy him the recreation of this harmless pursuit, more especially as he appears very prudently to confine his views to his own individual grati- fication. Complexity in a machine or instrument should certainly be as much as possible avoided; but if all instruments are to be condemned which have a diversity.of parts (which I un- derstand by the term complex), we should never have en- joyed the benefits of a clock, a loom, or a steam-engine. My idea of a high-pressure gauge is, that it should be use- ful; but if it is intended to be merely an amusing toy, why then I should commend Mr. Russell’s choice of what he lauds so much as being simple and easy. The instrument described by your correspondent in the last Number of your Magazine, is substantially the same as the common gauge which has been in use a long time past at the Portable Gas Works, where its defective and uncertain operation has been long known,—practically ‘known in the way of business, not speculatively conjectured: in confirma- tion of which I beg to state, that the superintendants of that establishment were lately in serious contemplation of erecting a gauge 70 feet long, in order that the divisions of the scale might be of adequate length. This simple fact is, I think, a complete answer to Mr. Russell’s crudities. Mr. R. seems to entertain great fear of its being practicable to make a “ tight joint between the glass tube and metal box.” It ——— Mr. Samuel Seaward on High-pressure Gauges. 191 It gives me pain to observe this display of ignorance; for I am sure I felt disposed to ah credit to that gentleman for a greater share of mechanical skill than what such doubt would seem to argue. The making of such a joint is an every-day ope- ration. However, to tranquillize his fears upon this point, I beg to say, that if a trifling escape of air should take place at this joint (which is quite absurd to suppose), it would not neces- sarily prove fatal to the instrument; because the defect can in a few minutes be detected and remedied by a method which for simplicity and ease will, I flatter myself, almost satisfy the fastidious notions of the worthy gentleman himself. The method of rectifying “my own” gauge, I ought to have included in the description which I had the pleasure of* transmitting to you; but it was inadvertently omitted: and I beg to return my grateful acknowledgements to Mr. H. Rus- sell for affording me the present opportunity of supplying the omission. All gauges acting by the pressure of confined air require occasional rectification, because, from the oxidation which takes place on the surface of the mercury, a portion of the air becomes absorbed ; and if oil or other liquid be employed in- stead of mercury, there will be as great inconveniencies. It is proposed that the chamber A (vide description of the gauge in your Magazine for January last) should be furnished with a small screw plug, and the induction pipe (e) with a small stop valve, similar to what is employed in the common gauge: by the closing of the latter the pressure of the gas will be shut off, and a communication made between the chamber B and the external air: in a similar manner, if the screw plug be removed, a communication will also be made between the chamber A and the external air: therefore, if there should be, from any cause whatever, a deficiency in the proper quan- tity of inclosed air, it will thus. be immediately supplied, and the equilibrium restored. And with regard to any insensible escape of air at this joint, it is proper to observe that as the pressure of the gas is generally above 20 atmospheres, the mercury will therefore be some height up the glass tube; con- sequently the joint in question will mostly be sealed, and all escape totally prevented. With many apologies for troubling you with such a long letter, I remain, gentlemen, Yours &c. London, March 8, 1824. SAMUEL SEAWARD. XXXIV. Me- [ 192 ] XXXIV. Memoir on the Variations of the reflective, refractive and dispersive Powers of the Atmosphere,§c. By 'T, Forsvrr, M.B. F.L.S. Member of the Astronomical and the Meteoro- logical Societies of London, and Corresponding Member of the Academy of Natural Sciences at Philadelphia, §c.* yN the infancy of every science, the first great object to be achieved is the accumulation of phenomena appertaining thereto. In proportion as we are enabled to Jay out these in their natural order and arrangement, in the same proportion we advance the science; and where we are enabled to unravel the particular causes of each, we promote a knowledge of it in the highest degree. In the following observations it will be found that I have been enabled by observation and reflection to collect a con- siderable number of facts, and to place them in some sort of arrangement. And though much progress has not yet been made on the development of their precise causes, yet such as has been already known has been arranged in a way which is likely to facilitate and direct the future inquiries of more able and industrious speculators than myself; and it is with a view of thus engaging the cooperation of the many intelligent members which compose the Meteorological Society, that I have ventured to obtrude the ensuing crude observations on their notice at this early stage of our investigations. The refractive power of the atmosphere has been long well known, and corrective tables of mean refraction intended to be applied to astronomical observations have been em- ployed for many years. In my endeavour, therefore, to be brief, in order not to become obscure, I shall avoid as much as possible the reiteration of observations already before the public, as the reader may refer immediately to Bradley’s tables, and to various works on refraction. But though the refraction of light by the intervention of the atmosphere is well known, that part of the subject which more immediately belongs to meteorologists, has been particularly neglected ; I mean the Variation in the Atmosphere’s reflective, refractive and dispersive powers, resulting from the diffusion therein of different modifications of cloud at different times and places. And the various effects which this aforesaid variation produces, considered as a fluctuation in the prismatic property of the air through which the modified light of the sun, moon and stars se- verally is transmitted to the inhabitants of our globe. The object of this paper is therefore to show the liability of the * Read before the Meteorological Society of London in February and March 1824, and published by permission. atmosphere _ Dr. Forster on the dispersive Power of the Atmosphere. 193 atmosphere to great variations in this its power of reflecting, refracting and dispersing the rays of celestial luminous bodies, and consequently the necessity of some further corrective tables of refraction; and to show what particular modifica- tions of cloud produce these properties of the atmosphere in the highest degree by being diffused therein. Previous to entering into the ensuing inquiry, I wish to caution the general reader against ever confounding reflection, refraction, and prismatic dispersion, which are distinct pro- perties. For example, the lightness of the sky in the day time is produced by the reflective power; while its appearing of a blue colour is an effect of a certain property which accom- panies it, whereby certain blue rays are separated from the rest. As amore striking example of the dispersive power, I may instance the beautiful red, crimson, and yellow colours of the clouds produced on certain occasions by the light. of the sun reflected by their surfaces, being refracted and dispersed by the aqueous atmosphere in its passage to the earth’s surface. I am aware that the clouds themselves may on some occa- sions possess the property of separating light ; and to this cause I was formerly inclined to ascribe their colour; but subse- quent experience and reflection have convinced me that the most brilliant tints seen in the clouds are the result of the dispersive power of the aqueous vapour existing in a state of general diffusion in the lower atmosphere, whereby the light reflected from the surface of the cloud is prismatically dispersed into separate rays in its passage through the lower atmosphere to the earth. It must be borne in mind, that my observations below do not relate to those remarkable and special refractions which occur in certain definable clouds, as the rainbow, which re- sults from reflections and special refractions of certain rays at a determinate angle in the mimbus or raincloud, producing con- centric rings of colours conformable to their different degrees of refrangibility. Nor do I include those special refractions of light in its passage through the cirrostratus, called halos, whereby concentric coloured rings are produced in the order of their respective refrangibility, and reflected at an angle which equals the angle subtended by the semidiameter of the halo. I allude in this paper to the ordinary effects of more thinly diffused and almost invisible cloud in the atmosphere, through which the luminous celestial bodies appear clear and distinct, but which nevertheless refracts and disperses their rays in some degree, even in apparently the clearest nights. Refraction has been hitherto considered as so general an effect of the atmosphere, and so unconnected with any par- Vol. 63. No. 311. March 1824. Bb ticular 194 Dr. Forster on the Variations of the reflective, ticular cloud, that universal tables of mean refraction have been made out, as if they would apply to all places. This is, however, an essential error: and in developing it I find the subject naturally divides itself into three distinct considera- tions, as follows: : On the Variation in the refractive Power of the Atmosphere at different Times of the Night and Day and on different Oc- casions and Seasons. There is one question in the history of refraction which for obvious reasons ought, if possible, to be cleared up; namely, Wherein consists the dispersive power of the atmosphere, which is found to vary at different times and in different places? To me it appears that this variation is owing principally to the quantity and nature of the aqueous particles suspended in the air. Astronomers have hitherto confined their considera- tions too exclusively to the refractive property of pure air, and have overlooked the circumstance that the atmosphere is seldom pure for any length of time; they have consequently not taken into account the varied effects of different sorts of dif- fused vapours, which, though unseen by the common observer, exist in the air in different proportions at sundry times and places, and which prevail much more at some places than at others. I was led to discover this by observing the vast dis- proportion between the result of my observations on the stars made at different times and seasons. In observing the planets and brightest of the stars through prismatic glasses, I found that the spectrum was less oblongated while the red colour was more distinctly apparent at the time of the first falling of the dew than at almost any other time of the same nights. Venus and Jupiter afforded a fine opportunity of ascertaining this fact last spring, as these planets could be both seen of an evening as early as the period of the vapour point*. * The vapour point is that precise period which occurs in the progress of evening, when, from the declining temperature, the air can no longer hold in solution the same quantity of aqueous gas that it maintained du- ring day ; and when consequently the aquosity is first deposited in the form of visible vapour or cloud, and gradually descends to the earth; on arriving at the surface of which it eventually forms a stratus or fog, called for this reason the fallcloud. In the morning the counterpart of this process takes place, and the gasified water being taken into the composition of the air again, ascends, till rising into a colder region it is again condensed into visible clouds which float on the vapour plane, or that precise elevation whereat the air begins to be teo eold to hold the vapour in solution. At this elevation it forms clouds dissimilar in their modifications, according to electrical causes which exist in the air, but generally speaking cwmuli, the lighter modifications of cloud occurring higher up from local electrical and other causes which disturb the equilibrium of the temperature of the at- mosphere. And refractive and dispersive Powers of the Atmosphere, &c. 195 And the most common observation on the rising and setting moon will always confirm it on favourable nights. On other occasions, at the same time of night, I found an unexpected difference in the appearance of the spectrum of the very same planets; the violet and in general the most re- frangible colours being most conspicuous, and the spectrum being more oblongated than ordinary. To reconcile this difference of effects with existing causes apparently so similar, was now an interesting object; and at last I found out that the difference was referable to a difference in the quality of the falling dew, or diffused cloudiness. The greater prevalence of the red in the spectrum uniformly accompanied that state of the atmosphere when the cirro- stratus or wanecloud diffused itself after sunset ; while the more oblongated spectrum with the violet and most refrangible co- lours attended an atmosphere in which the descending dew was stratus or fallcloud. I will not say positively that in the first case the falling mist was itself cirrostratus, but it was a different kind of mistiness and less purely white, when seen in the valleys, than the common mist, and it happened when there were cir- rostrati in the higher air. Another circumstance which con- firms my explanation of the phenomenon is, that during the falling of ordinary dew in clear and settled weather, particu- larly with east wind, the horizontal haze shows beautiful tints of the more refrangible colours, varying upwards, so that the atmosphere becomes a sort of natural prism, of which I have cited many examples in my “ Researches about Atmospheric Phenomena.” Whereas when cirrostratus prevails, particu- larly before wind, the red is the predominant colour of the haze, and also of the clouds above it,»which appear of the finest crimson and vermilion. In some cases I believe the clouds may themselves become prismatic, and the colour of which they appear may be produced by their own structure; but it is more generally the effect of the haze through which reflected Trays pass in coming down. Clouds in this case may be com- pared to planets viewed in a prismatic glass, their surfaces re- flecting the borrowed light of the sun, which becomes dispersed by the chromatopoietic properties of the atmosphere through which it passes. Another circumstance which I witnessed several times in November 1822, and which is of common occurrence, strik- ingly corresponds with the above observations; namely, that clouds whose irregular surfaces and depending fringes were of a golden or silvery colour, that is, reflected all the sun’s rays Just as they received them, during a whole afternoon, were, on the occurrence of the vapour Mel suddenly turned red as at 2 y 196 Dr. Forster on the Variation of the reflective, by some dispersive power imparted to the circumjacent atmo- sphere by the first falling of the dew. The state of the atmosphere which shows the red colour for any length of time is a forerunner of high wind. * "There is an obscurity of a denser kind which often causes an apparent dilatation of the disks of the celestial bodies, which it elevates without colouring them. The moon for instance looks pale, expanded and confused. This state is a prognostic of rain, and is contrasted to the former as well as to the clear- ness of the serene sky which follows an ordinary fall of dew, in a well known proverb expressive of the prognosticative co- lour of the moon on each several occasion :— . « Pallida luna pluit, rubicunda flat, alba serenat.” Another state of the cirrostratus, when diffused, seems to possess dispersive properties of a very peculiar nature, re- fracting certain coloured rays at an angle of about 5°; and others at an angle of about 23°, so as to cause two concentric halos or rings of colours ; the inner one being about 10°, and the outer one about 46° in diameter. Sometimes single rings occur which are colourless; but as all these pheenomena do not pro- erly belong to our subject, and are otherwhere treated of, I shall not dwell longer on them. All the above circumstances show that the changes in the qualities of the diffused vapour in the air must cause a great variety in the atmospherical refraction. They also explain how the atmosphere about different places may have a different mean refractive power, according to the local prevalence of the above diversified vapours which hang init. or I am not certain whether, independent of temperature and pressure, the pure atmospheric air differs in its refractive power all over the world: I believe the difference to arise from the vapours always more or less suspended therein and generally electrified. Two more facts confirming my hypothesis must now be cursorily mentioned. The east wind produces changes in the appearance of the spectra of the celestial bodies, even in the field of ordinary telescopes: the spectrum seems to vi- brate or dance about in the field of the glass in a way that defeats many very delicate observations. Had not this re- mark been confirmed by other people, I should have ascribed it to the nervousness of the observer, the east wind being very liable to produce nervous disorders of the eyes and other parts. I have not observed the precise effect of the east wind on the larger prismatic spectra, as far as respects their colours; but the whole spectrum seems often on such occasions to move, and to fluctuate more than ordinarily. Astronomers, ever since the time of Newton, have known that refractive and dispersive Powers of the Atmosphere, §c. 197 that pure atmospheric air will vary gradually in its refrac- tive powers according to the degree of heat; and remark- able instances of the great elevation of the disk of the sun above the horizon in cold climates, when calculation showed him to be below it, have been adduced as striking exam- ples. But it should be remembered by all, and it is already known to meteorologists, that changes in temperature are never unattended with changes in the quantity and modification of aqueous vapours suspended in the air. And this circum- stance must add considerably to the effect of low temperature, and may impart to an atmosphere condensed by cold some great and peculiar dispersive properties. The inordinate elevation of the mast of ships at sea by refraction is an instance and proof of the undoubted great effect of vapours occasionally suspended in the air. The east wind is connected with the arrival of peculiar vapours in it, and the vibration or irregular movement of the star in the telescope may be owing to such vapour being agitated by the electrical commotions that so generally attend a change of wind from any other quarter to one blowing from the east. Besides the general want of correspondence between the re- sults of different observations, where it is necessary to subtract a given quantity of refraction, we may make a particular ob- servation on the still greater disagreement that is found to exist in the declination of several particular stars, as published by different observers; for this disagreement, when applied to certain individual stars, is referable to a compound cause; for the light of the stars severally being composed of different proportions of the primitive colours, the red ones, as Alde- baran, Arcturus, and Betalgeus, are less refrangible than Sirzus, Lyra, Capella, and the white stars in general. Of this I shall treat in the third section. It may suffice to remark it slightly here, in order that, when we are considering the varieties in the atmosphere’s dispersive property, we may also take into account the compound effect a nie by the various colours of the stars whose light is thus variously dispersed. The projection of Aldebaran and other red stars on the disk of the moon when the conjunction happens near to her upper limb, as noticed by Mr. Lee*, is an illustration of the above fact; the greater proportionate refrangibility of her white light, than that of the red light of the star, elevating her apparent disk so as to cause the star to seem to be within it just before or after the respective points of contact. When the wind first changes to become east, and when the * I wish my readers to peruse the whole of Mr. Lee’s ingenious paper in Phil. Trans. ; for though it becomes necessary to cite it, in order to make due acknowledgements, nevertheless every individual Essay should be read entire, and not in citations. air 198 Dr. Forster on the Variation of the reflective, air is encumbered with the cirrostrativeness of the wanecloud, then all the celestial bodies appear redder than at other times, from the greater disposition of the air at those times to se- parate and transmit the red colour, which must considerably influence the foregoing observations. The last observation I have here to make relates to a phe- nomenon hitherto entirely unexplained. I allude to rapid alternations in the colour and brilliancy of the light of certain stars viewed near the horizon. Some years ago, on looking towards the constellation of the Scorpion, I observed a remarkable changing of colour in the fluctuation of Antares: for a second or less of time it ap- peared of adeep crimson colour, then of a whitish colour; then the crimson was resumed; and so on at alternating periods. Sometimes every other twinkle showed the red colour, while the alternating twinkle appeared of the ordinary colour of starlight. What is commonly called the twinkling of a star seems to be an apparent fit of dilatation and increased brilliancy rapidly succeeded by the opposite state of apparent contraction of surface and dulness. I have observed, also, that the twinkles are of longer or shorter duration, at different times: now, in general, the intense red light I allude to occurs in every alternate dilatation ; but sometimes only in every third, and at other times quite irregularly: moreover, it lasts longer sometimes than at others, and scarcely ever exceeds two seconds of time at once. This phenomenon as viewed in Antares was par- ticularly conspicuous at Clapton, in autumn 1809, at Tun- bridge Wells on June 19, 1817, and during the whole summers of 1822 and 1823 at Hartwell. I.saw this phenomenon also in other stars, in France, in September 1823; and I have seen it in the summer of 1822, in the atmospheres of Switzerland, Alsace, and all along the Rhine: it is evidently not confined to any local cause. I have formerly published accounts of this phenomenon in the Journals, and have ascribed it to some sort of change in the star itself, or to a revolution round an axis, whereby different coloured portions of the luminous sphere might be presented to us: but this explanation vanishes on a moment’s reflection ; and I am inclined to ascribe it to some atmospherical cause. I have sometimes thought that the upper portions of the atmo- sphere might have some undulatory motion, and that the al- ternating colour might be produced by its refractive powers : for the atmosphere, in this case, acting as an imperfect prism, might present different colours, according to the varying in- clinations of its wavy surface*. I have thought, too, that por- * See Phil. Mag.vol. xlix. p. 452 ; and the Perennial Calendar, Jan, 16, P- 17. tions refractive and dispersive Powers of the Atmosphere, §c. 199 tions of the aqueous atmosphere, possessing different prismatic powers, might be transmitted downwards in dew, or that there might be some other unknown motion in the real air, which might cause the appearance. Antares, Betalgeus, and some other red stars, show this change of colours very strongly, par- ticularly the former: while Szrzus and the brilliant white stars show this alternation of colour ina less degree. It is not ob- served in Procyon, is weak in Capella, but is considerable in Vega and in Arcturus, the latter being a red star. Antares shows this phenomenon more brilliantly than any of the others. Differences in the composition of the light of stars may explain these varieties of effect. Nobody can, I think, reflect on all the above details, hasty and imperfect as they may be, without at once seeing the importance of extending our observations on the phenomena to which they relate, in constructing tables of refraction; and I shall still be excused, I trust, in the absence of more ma- tured and extended details, for this imperfect attempt to ex- cite the attention of philosophers to facts which seem calcu- lated to produce an important influence on many of our most useful astronomical calculations. Il. Of the Variation of the mean refractive Power of the Atmosphere in different Places. Although the refractive and dispersing power of the atmo- sphere varies at different times in the same place of observation, - yet by dividing the sum of a vast number of observations by their number, we shall get at a mean or average of the refractive power of the atmosphere of any particular place. This I call the mean refractive power of the atmosphere, and this mean differs very much in different situations, so that tables of mean refraction will not apply universally, but must be made out separately for each place of observation. Thus a cor- rection which would be applicable to observations made at Greenwich, would not equally apply to Dublin or to Paris, much less to Palermo or the Cape of Good Hope: and they would be still less applicable in Peru, where the dispersive power of the atmosphere is prodigious. I was led to the adop- tion of this opinion, in the first instance, by analogy, it being strictly conformable to a thousand other corresponding in- stances of local variation in atmospheric phenomena. Ex- periment seemed to confirm it. And I have lately heard of a further corroboration which this opinion has received from the able observations of Dr. Brinkley, communicated to the Royal Society. But as I have only heard casually of that paper, 200 ~— Dr. Forster on the Variation of the reflective, paper, and have never seen his observations, I cannot speak positively to that point. If the opinion which I have long entertained, that the mean refractive power of the atmosphere varies in different places, be correct; its promulgation may lead to important results: it may explain certain apparent discordances in the places assigned to the fixed stars as described in different catalogues. For if corrective tables calculated for Berlin or Paris were to be applied to observations at Greenwich, there might be a considerable difference in the result. Another very important observation results from this con- sideration. Suppose, for example, a given corrective table of mean refraction were to be applied to a catalogue of ap- parent places of the fixed stars observed at Pisa a hundred years ago, and that the same table were to be applied to a catalogue observed this year at Dublin, the result of a comparison of the two catalogues would be a positive error. For Dublin and Pisa requiring a different correction, altogether independent of longitude and latitude, and depending solely on the dif- ferent refractive powers of their respective atmospheres, the consequence of applying the same corrective table to the ob- servations of both places would be the certain error of one of the catalogues. And as one catalogue would, according to our supposition, be a hundred years older than the other, the stars would be thought to have changed their places. Some misap- plication of tables of refraction seems to me to be the cause of an idea of a southern motion recently promulgated by certain astronomers. Independently of the great prima facie improba- bility of such a motion, it seemed to me, when I first heard the opinion mentioned, that it would turn out to be an error de- pending on the want ofa proper application of corrective tables of refraction. Ispeak, however, on the point with deference to the better judgement of learned astronomers. III. Of Varieties in the Composition and Nature of the Light. of different Stars, considered as still further varying the Effects of atmospherical Refraction, Reflection and Dispersion. It must have occurred to almost every body to perceive that the colour of different stars is very dissimilar; that some appear more red or copper coloured, others yellow like brass ; some of a bright and almost silvery whiteness, while yet others are of a dull white colour. These differences become much more striking when viewed through such bad telescopes as, being but imperfectly achromatic, become in a measure pris- matic, and separate the primitive rays of light, producing a é coloured refractive and dispersive Powers of the Atmosphere, &c. 201 coloured spectrum in the field of the glass. By the adapta- tion of a more perfectly prismatic lens to the telescope, we get a still more distinct spectrum, and are enabled to contemplate the particular composition of light possessed by each star re- spectively. I was not aware of the best means of detecting these differences, till I read the excellent paper On the Disper- sive Power of the Atmosphere, by Mr. Stephen Lee, published in the Transactions of the Royal Society*. As some of my own observations coincide with those detailed in the aforesaid paper, I feel additional confidence in giving them to the public, as the acuteness and ability of that gentleman as an astronomer are well known. Mr. Lee viewed the stars through a prism adapted to the eye glass of a reflecting telescope; and, prompted by a laudable desire to ascertain how far the disper- sive power of the atmosphere could produce an effect on astro- nomical observations, he proceeded to examine several stars, with a view to ascertain, if possible, the exact degree of se- paration of the several rays. As the above paper ought to be read by all observers, I shall not extract any of the observa- tions now, but proceed to the subject under consideration,— the varieties of stellar light. According to my observations, the stars should be classed according to their colours, into the red, the yellow, the bril- liant white, the dull white, and the anomalous. For though each star may differ somewhat from every other, yet we shall be assisted by this general classification. When observed with a prismatic glass as above described, Sirius shows a large brush of extremely beautiful violet colour, and, generally speaking, the most refrangible rays in great quantity. The same applies more or less to all the bright white stars. Procyon is far less beautiful than Sirius, and shows more of the yellow colour. Aldebaran, together with many of the other red stars, exhi- bits a very small proportion of the more refrangible colours. Arcturus much resembles Aldebaran, but differs in the lesser proportion of the red to the other rays. \ Betalgeus is another red star, little inferior in magnitude to the two above. This star shows also but little of the more refrangible rays; but the spectrum is always a bad one, and is for some unknown cause more liable to fluctuation than the above two. Antares, the most extraordinary star of all, contains, like Aldebaran and Arcturus, much red light; but owing to its * See Supplement. Vol. 63. No. 311. March 1824. Cec greater 202 Dr. Forster on the Variation of the reflective, greater southern declination, as well as to something very pe- culiar in the composition of its light, we cannot get so perfect a spectrum as might be desirable. This star, too, exhibits in the greatest degree a peculiar and hitherto unexplained phee- nomenon, which will always interfere with our observations on its permanent spectrum. JI allude to the rapid permutations of the colour of its light, every alternate twinkling, if I may so express myself, being of an intense reddish crimson colour, and the alternate one of a brilliant white. As I have before de- scribed and speculated on this phenomenon, common, though in a less degree, to other stars when near to the horizon, I shall not further dwell on it here, but observe that Antares, considered with reference to its light, must be put among anomalous stars. Atair in the Eagle, and also the dull white stars, exhibit a vast quantity of intense green light. ‘This is very conspicuous in many stars of the 2d and 3d magnitudes. The planets likewise present spectra very considerably dif- fering from each other. Jupiter possesses all the colours; but from something in their respective proportions, or from some unknown cause, this planet is liable to produce, even in good and almost achromatic glasses, so bad and so coloured a spec- trum, that I have always found him a disagreeable star to ob- serve. Asa prismatic spectrum, however, he is beautiful. ‘The green colour seems somewhat deficient in his spectrum ; never- theless Jupiter appears green in comparison with Szrzws when an opportunity offers of viewing both at one time*. Venus appears less green than Jupiter, but still she is not of so bright and blueish a white as Sizzus. Her spectrum in the prismatic glass shows most of the rays, but the green colour is very pale. Saturn seems composed chiefly of the mean rays, and has a very small quantity of the extreme colours. Mr. Lee, who also notices this, subjoins the following judicious question— Whether this may not explain why Saturn bears magnifying better than Jupiter or Venus ? Mars, who shines with a red light, appears as a spectral image on the prism to possess less of the middle and most refrangible colours. The red is very conspicuous in the prismatic spectrum. Mercury is said to show a similar spectrum: I confess I have not made observations on Mercury myself. * We may imitate the different colours of the spectra of the several stars and planets, by burning antimony, steel, and other metallic filings, in pyrotechnical jerbs, and viewing them through a prism. Compare the prismatic spectrum of ignited steel with that of Jupiter, of burning anti- mony with Sirius, of copper filings with the spectrum of Mars; and so on. Of refractive and dispersive Powers of the Atmosphere, §c¢. 203 Of the varying spectra of the Moon, and the composition of moonlight, I shall speak hereafter. The next consideration is, the effects which the above-de- scribed variety in the colour of the light of the celestial bodies will have on our astronomical observations: and it appears to me that this effect will be very considerable. Sir William Herschel has already noticed this circumstance, and has ob- served, that the prismatic power of the atmosphere should not be overlooked, as in observations on very low stars it must make a great difference in the correction which might become necessary. He has stated the measure of two dia- meters of ¢ Sagittarii, and from his observations thereon de- duced the refraction of the extreme rays as being about 4 + the mean refraction*. b oe To me it appears evident that the different stars will, in consequence of the different composition of their light, require very different corrections; and that tables of refraction should not only be made out for each observatory, in order to apply to the mean refractive power of the air in different places as before described; but also, that some rules should be ap- pended for applying a correction for each particular class of stars, according to their predominant colour. As a natural deduction from the foregoing facts, we must infer that the real declinations of Sirius and of Aldebaran, for example, cannot have been determined by the application of the same correction to the apparent places of both of them; since Sirius is composed of a large quantity of the most refrangible colours, while Aldebaran is particularly deficient in them. We cannot, I think, easily pass by the above facts, without inquiring into their particular causes, which will be found to involve us in some exceedingly curious speculations. The difference in the colour of the light of the fixed stars is probably owing to a real difference in the proportions in which the several rays are combined. Thus Sirius sends forth more of the violet; Aldebaran more of the red; and perhaps Capella more of the yellow rays. Atazr and the dull white stars perhaps have more of the yellow and blue together, and less of the red, so as to make green light; and so ont. The stars differ too in the intensity or brilliancy of their light; the largest apparently not being always the brightest. And it is curious to observe that some stars seem * Phil. Trans. vol. xxv. On Double Stars, by Dr. Herschel. : + I have worded it thus on the very doubtful supposition of three pri- mitive rays, merely in conformity to received opinion: phenomena are decidedly against that notion; for I cannot separate their green light in the spectrum. Cc? to 204 Dr. Forster on the Variation of the reflecteve, to possess a greater power of pee through an imper- fectly obscure atmosphere than others o equal apparent big- ness, as the Pleiades and the Hyades. On the other hand, the two small stars in Cancer, called Aselli by the Romans and “Ovo: by the Greeks, were found to be obscured much before the rest during the progressive condensation of the atmo- sphere; and their dimness and progressive disappearance, to- gether with that of the nebula Presepe, was consequently re- garded as the first sign of approaching rain, as 1s mentioned by Aratus in his Diosemea, and which had been before observed by Theophrastrus in his treatise Tegi onparwy d:rdiv. The pas- sage is exceedingly curious, and is as follows : ~ /, m” c 8 ‘ "Ev ra Kaguive bho doréges civlv, of xaAovjsevos OvO1, WY TO peraky « ey ~ rb vedéArsov h Oatyn xadovuéyy® ToUTo 83 dv Copdides yevnras, VOarixoy. And afterwards he observes respecting the signs of rain: ‘H rod dvov darvy ei cuvicraras nal Sopeod yiverau yelmava on- pecelver. Aratus in following up this observation makes a distinc- tion between the indications of the northern and those of the southern of the two stars, which we can hardly reconcile with any conceivable hypothesis. Eis piv mag’ Bogino, vorm 8” emitgyeras aAAos" Kal ro} wiv xaréovran dvorr peoon 02 Te OaTIN, "Hre xal tEamlyyns mavrn Ards evdscovros Tiver’ dpavros GAn* tol 8: duporéguibey idvres "Aaréiges drAAnAwy abrooyedoy ivdcaAAovrees® Odx bAiyw xeman tore xAdCovTau digovgas. Ei 83 pedaivytas, 70h 8 atrix’ eoimdres cow "Aoreges audoregos meh °° Udars onwaivorey. Ei 8 6 wiv éx Bogdw darvys dwevyvd pasivy Aemris tmaxavowy, vorios 8 Gvos &yAads em, - Azidér Gas caver vorou' Bogéw 82 wera OH "Eumaarw dyauoevrs Guswonevw te Sonevery. The peculiarity of this observation has struck many com- mentators, and I find the following note appended to the above passage. Meteorologica astronomicis confundit. Nam diverse harum stellarum species, non a propria ipsarum atmosphera, sed a nostro aére efficiuntur ; quare, ergo, he, magis quam alie stel- le, per obscuritatem suam tempestates portendere possint? St quidem ab ipsarum aére aut aliquo circa eas fieri possit speciet variatio; quis credit tantam inter tam remota sidera relationem existere, ut aliquid, in stellis visum pluviam in mundo premo- neret ? Sensus est —Quod etiam confestim, ccelo sereno, fit evanidum refractive and dispersive Powers of the Atmosphere, &c. 205 evanidum totum; atque stelle utrimque coeuntes, si invicem vicine apparent ; non modica tempestate arva inundant. Si autem nigrescat, rursus vero eodem colore ambe stelle existunt, pluvias significant. Si vero hic (vos) qui est e presepis borea modice tenebrescens, languide splendeat, cum austrinus asellus lucidus sit, ventum Austrum expecta. Boream vero e contra tenebrescente lucenteque observare oportet.— Arat. Dios. 167. Many corresponding quotations might be added. Some years ago Mr. Barker published a paper in the Phi- losophical Transactions, tending to prove that many of the stars had changed colour in the lapse of ages; some being described as red, which are now white. I do not, however, attach any importance to the remark, because the ancients used the names for colours with the utmost latitude and variety of significations. Rubere, splendescere, purpurascere, and many others only signified to shine brightly*. Nevertheless, certain remarkable changes in some stars, and the alternate disappearance and reappearance of others, while some have been actually lost, seem to warrant an opi- nion that the gradual work of destruction and reproduction, sO conspicuous through all mundane nature, is likewise going forward on a grand scale among the ponderous systems of worlds which fill eternal space. ‘This consideration does not bear immediately on the subject under discussion, but it ought to be kept collaterally in view. Hitherto we have been discussing the probable causes of the colour of the fixed stars shining by their own light, and have supposed the differences of colour to result from the re- spective composition of the light of each. But in considering the planets which shine only by reflecting the light of the sun, we have other things to take into the account. If the planets have no light of their own, the difference observable in their respective colours must arise from a difference in the dispersive powers of their own respective atmospheres, through which the sun’s reflected rays may be separated in their passage. We know, indeed, little or nothing about the composition of pla- netary atmospheres; but analogy would lead us to ascribe the variations of their light rather to properties of their surround- ing atmospheres, than to the colour or other qualities of the substance of the planet itself. It may be observed, that the particular position of the Ring of Saturn does not affect the colour of his prismatic spectrum, and therefore probably it throws back the same sort of light as the body of the planet does. Of what are called the Belts of Jupiter, we know almost nothing; but we may conjecture that they may have some- * See Phil. Mag. vol.xlix. p.49, where I have endeavoured to refute this “ti thing 206 Dr. Forster on the Variation of the reflective, thing to do with the peculiar tendency of this planet to produce a bad spectrum for observation even in the best telescopes. Out of the consideration of the chromatopoietic property of the atmospheres of the planets, a question arises, Whether that property be subject to variation? There is a manifest difficulty in ascertaining this, because the reflected light of the sun passes through our own atmosphere as well as that of the planet; and consequently we cannot always tell to which atmosphere to refer any colour which we may observe in the spectrum. Observations made on two or more planets at once, where the changes in the light of the two or more severally did not correspond, might lead more directly to the solution of this question. But we are getting now away from our object, and must retrace our steps before we wander too far into the wide field of speculation which lies open before us. Observations are as yet wanting to establish and sy- stematize the facts briefly alluded to above; but it is to be hoped, from the united efforts of numerous astronomers and meteorologists now beginning to be in communication with each other all over the world, that the desiderata, quantum possunt, will be supplied. The present subject affords an example of the natural connection between the two sister sciences, and affords a hope that the many learned men who compose the Astronomical and Meteorological Sccieties will cooperate in the attainment of a common object, and that the peculiarities and variations of atmospheric refraction will be more fully known than they have been hitherto, by the multiplied observations of individuals acting in concert*. Of the Colours of the Moon. The Moon viewed in the prism seems to possess all the co- lours; and their proportions, as far as we can judge, are very similar to those observed in Venus. But the observations I am about to make on the lunar disk, are intended rather to confirm a point that Iam contending for in meteorology, than to esta- blish the proportion which her component rays of light bear to * It appears that the ancients were not inattentive to the different co- lours of the planets. Pliny thus distinguishes them; which, though not a very clear description on account of the very promiscuous use of names for colour among the ancients, shows at least that considerable differences in their light had been observed even in his time. In Hist. Nat. lib. ii. cap. 18. we find, “ Suus quidem cuique color est; Saturno candidus, Jovi clarus, Marti igneus, Luci- Jfero candens vesperi refulgens, Mercurio radians, Lune blandus. Soli cum orilur ardens postea radians.” He then goes on to notice the varying co- lours of the same planets and of the Sun at different altitudes and in dif- ferent states of the atmosphere. Of the observations of the ancients I shall say more in a future Number. each refractive and dispersive Powers of the Atmosphere, Sc. 207 each other. Viewed as I have seen her from the heights of mountains and in the clearest nights, she appears of a brilliant white light. And the varying colours of her disk seem to be caused by varieties in the colouring power of our atmosphere alone. What I am trying to clear up is, that astronomers, in considering the refractive powers of atmospheric air, have over- looked the circumstance that there is almost no state of the air in which the diffusion more or less of aqueous gases or cloudiness does not exist, though in a very small degree; and that on this diffusion of cloudiness depends in a greater degree than is imagined, the dispersive power of the atmosphere and the peculiar colours of the celestial bodies seen through it. I shall conclude my remarks on the Moon with the de- scription of a curious lunar refraction, which I observed some years ago. About seven o’clock in the evening, the Moon being five days old, I noticed a remarkable double refraction of her image of the following form and relative position ) ), that is, two distinct crescents instead of one, and both so pre- cisely similar as not to be distinguished ; so that I said toa gen- tleman who was with me, “ Which do you think is the Moon, and which the paraselene?” Neither of these images was coloured, and both were as bright as the ordinary brightness ofthe Moon. The cause of this phenomenon did not suggest itself at the time; but I have since thought that it so much re- sembled the double refraction by which two images are seen in certain laminated spars, that it might be referrible to the same cause, and that it might be an indication that there ex- isted atmospherical laminz at that time. I do not conceive that the existence of laminated air is by any means improba- ble, and it may be connected possibly with the various con- trary currents of air, which exist contemporaneously in suc- cessive altitudes in the atmosphere, of which observations on the varying direction of small air balloons have furnished me with sida Mon proof. The above subjects deserve more consideration than they have hitherto met with, and I trust many members of the So- ciety will co-operate with me in pursuing them. P.S. Since I wrote the above, I have repeated various ob- servations on the stars and planets with a prismatic glass of another kind, the adaptation of a prism to the eye glass of the telescope being at all times an awkward contrivance. The re- sults have varied, however, but little from those above stated, and I subjoin the following rude table of the spectra of the stars observed during the present month, and arranged ac- cording to the intensity of light of the stars severally. Hartwell, Feb. 3, 1824. Dr. Forster on the Variation of the reflective, 208 *SINO[OD *djod BOW JY} os[e pue jYsI, Uaedd asuojUL YONI] *sked “a1 Ssay 94} pure “WYSI] par YOu *s1n0]09 “YO ssay ay} pue YYyor] par yon, *sIno[oo “Yat sso] OY} pue 4ysI] por youyy “sanojoo uvoul 94) pus “4yysI; Moped yon, ‘anyq a10ul ynq ‘sNIIg setquiasay “SnLIIG uvy} Moya4 a10ul pus “Ja]OIA ssa’T *SINO[O9 “Joa ysoOur dy} pue Ya[OIA jNJWuvEg *unwaads IUDUSIL TT ‘a]quiopisuoouy "110s 9Ues OY} pur 4se| ay} UeYy d10UL Joye Y “pat Jo aaidap Jaqvo1s B yytm “445s A190 4 “30198 JON ‘ayaa A190, ee Os Apaysys soyeusr3[y “a[qIuJOOSIP JON] ‘Apurey par YJIM sazeVuloz Vy “wounngzony ayy UL sunojoa fo uoynusayypy ‘apy AI9, “qse] oy) UB a1OUl 19YIVY “Ayqe -JopIsuoduy -A|qeaapisuod “Surpooeid ay} ueYy ssary “A[qesapisuoy) “Surpaoa1d ay} ueY} ssa’T ‘A[qearapisuo— “YORU sa7zyUuuny Jou £0 LOYJIY Af “anys ystonygy “Pad “ped “YSIPPPN “YSTMOTIO X ‘ony ysiontg ‘Ou AN ‘OU AN *.4n0]09 quaunddp “sysLIq $s] yeyMoUog “Apeaig “Apeazg “qystig “‘systg “queT [Ng "ysHysig ‘querying 419A “ssauynp Lo haounyng "2 B YIM poyreur st [nyWquop far yenba sayy saytusis = fsayqey, uoovayay Areurpso ayy ueYy ‘— snuru jo 10 ‘+ snyd so uosads00 uvau e jo yey auinbas s.ieqs ay} AaYIOYA aJOUAp soueU ay} JopUN sUdIS OY, “{"N qysyanig fo saipanjnsury ayz fo aarnzuasasdae 2190], é => "SINIDULA voldsg “Shao TV Lag “‘NVUvadaaty “snunLouy “W1ITdd¥—) “NOADOUT + “sniyig — “04s fo auoyy refractive and dispersive Powers of the Atmosphere, &¢. 209 It may be noticed that the alternating colours observed in the fluctuation, and recorded in the 5th column of the table, are ceteris paribus most observable when the stars are near to the horizon; and I have observed that the maximum of the intense red colour which distinguishes the alternate change happens at the elevation of about 10 degrees above it. The phznomena noticed by Kepler in the new star dis- covered by him in 1604 in Serpentarius, and now lost, if rightly recorded, afford a striking instance of the converse of what we usually observe. For in that large and memorable star, the colours were continually changing when the star was high, but when it got near to the horizon it was uniformly white. It is much to be wished that observations had been made on the changeable stars and on those that are now quite lost. The Stella mira may afford interesting observations. Comets ought also to be very accurately observed. The great comet of 1680, which is expected again in 1833, will probably be the subject of much curious research. The ordinary distribution of stars into the Ist, 2d and 3d degrees of magnitude, and so on, though it may serve com- mon purposes, is nevertheless very imperfect; the stars re- corded as being of the first magnitude differing as much among themselves as some of them do when compared with those of the reputed 2d magnitude. In the above table of large stars, I have endeavoured to arrange them in the order of their ap- parent size and intensity of light, the best way of ascertaining which is by observing the relative degrees of Jight in which each can first be seen, either at evening or morning, measured by a phetometer. But it is evident that this plan will include also their brilliancy, which is a thing quite different from their apparent size. Some small stars have a more piercing light than others for their size, as the Pleiades, for example. In order therefore to ascertain and compare the relative apparent size Alone, we must trust a good deal to our own judgement. It is my intention to pursue the above subjects, and to make as accurate comparisons as I am able between the bbe of individual stars, dispersed by means of prismatic glasses adapted to telescopes, and the light of various combustible substances in a state of ignition viewed through prisms. There have appeared to me to result some very extraor- dinary pheenomena, from the adaptation of a prismatic glass to different parts of the telescopes: but as I cannot account for them on any known principles, I only state the fact as a hint, in order that others may repeat the experiments. Finally, we must ever bear in mind that the retina, and the cerebral parts in connection with it, are a necessary part of the optical ap- Vol. 63. No. 311. March 1824. Dd paratus 210 M. Frauenhofer’s Description of a new Micrometer. paratus which we employ in all experiments on light; and we must guard against being deceived by any peculiarities or affections in our own organs of vision, which we need not fear, provided only we make the same experiments repeatedly and with due attention. (To be continued.] XXXV. Description of anew Micrometer. By M. FravEn- HOFER of Munich. * TB ERE is probably no instrument, if we except tne helio- meter, better adapted for determining the right ascension and declination of two stars, than the circular micrometer. To * this simple instrument, which can be applied to any telescope provided with a good stand, we owe, besides many other im- portant observations, a great part of those made on comets. Improvements in this instrument are therefore desirable. Some astronomers still prefer the rhomboidal micrometer for determining the relative places of two stars. It cannot be denied that the calculation of observations made with such a micrometer, is more simple than that made by the circular micrometer, and that the result possesses about the same de- gree of exactness, whether the difference of declination of both stars be great or small; while in observations with the circular micrometer we ought to have, for a smaller difference of de- clination, a smaller circular micrometer also. Any one pos- sessed of practical knowledge will soon perceive that a rhom- boid, in whatever manner it may be made, cannot obtain the prescribed form to such a degree of accuracy as is required for good observations ; whilst, on the contrary, there are seve- ral means of making a circle to a great degree of exactness. It cannot be expected to file out a hole exactly in a rhom- ‘ boidal shape. We may indeed obtain a rhomboid with straight lines, by screwing together bars of equal breadth ground per- fectly straight ; but to give the required angles of the rhom- boid is not very practicable. In stretching four wires, in the form of a rhomboid, we have to encounter the same difficulties, as far as regards the angles of the rhomboid; besides this, there is seldom a piece of wire exactly straight, even if ever so strongly stretched; but thin wires cannot be made use of for the purpose, because in a dark field of view they cannot be seen. ‘This is the reason why circular micrometers have such a decided preference. With the circular micrometer, consisting merely of the dia- * From M. Schumacher’s Astronomische Nachrichten, No. 43. phram M. Frauenhofer’s Description of a new Micrometer. 211 phram of the telescope, the zngress of a star into the field of view, cannot be observed with the same exactness, as its egress; because, since we do not know at which place it will enter, the eye is not directed to that point, and is consequently only di- rected towards it when the star is already in the field of view. With the open diaphram it is likewise difficult to let the star describe any given chord of the field; which is in fact neces- sary, because small segments give the declination, but larger ones the right ascension, more correctly. Instead of the open diaphram they have also frequently made use of a small ring, which, by means of four bars, is suspended in the field of view. A small ring can only accidentally succeed in being per- fectly round, as in good observations it ought to be; and even from its being suspended by wires, which may be stretched, its perfect form may be lost; and even the expansion or con- traction of the metal with which it is connected, may alter it. In order to have in the field of view of a telescope a small unchangeable ring, whose inner edge is exactly round, and remains so under all circumstances, I cut a round hole in a thin plate of glass, and fixed a small steel ring into it, in the same manner as glass-lenses are fixed in brass mountings ; viz. by laying over the projecting margin by means of a bur- nisher. After this ring was fixed in the plate glass the inner edge could be turned in a lathe exactly circular, which is done in a manner that leaves no doubt respecting the necessary ac- curacy. As the objects are seen through the glass as well as without it, we see the star approach the external edge of the small ring, and know where it is to appear at the inner edge ; the observer is consequently prepared for the inoment, and the ingress at the inner edge can be observed with the same exactness as the egress from it. Partly for the purpose of ob- taining, at the transit of both stars, the exact difference of de- clination, and that of the right ascension, partly to enable me to use one and the same micrometer likewise for smaller dif- ferences of declination, I have introduced two small steel rings, in the above-mentioned manner, into the field of view, where the diameter of the one is considerably larger than that of the other, and both of which are plainly seen at the same position of the eye-glass. Although the observations with this circular micrometer are more to be depended on than with the usual one, yet even these leave much more to be wished, particularly in the ob- servation of comets; and more particularly since the differ- ences of declination, derived from different observations, fre- quently deviate considerably from each other. One of the causes is, that in a comet, which is always badly defined, the Dd2 centre 212 M. Frauenhofer’s Description of a new Micrometer. centre must be estimated ; but we cannot judge with exactness whether the half of it has made its ingress or egress, because the other half is not seen, and the mere approach of a weakly illuminated object to a proportionally broad dark ring causes easily a deception in estimating the cortect time. ‘Through the eye-glass, which cannot well be achromatic, the inner edge of the small steel ring becomes blue, but the outer one is seen to be red; the star on the contrary is blue outwards and red inwards, so that, for instance, at the egress of the star from the inner circle of view, the blue end of it gets to the blue edge of the small steel ring, and the star lengthens itself still more, which must cause an uncertainty respecting the time of its egress. As the star always lengthens itself in the direction of the centre of the field of view, and both the passing stars usually cut different segments of the circle, the errors of ob- servation cannot easily compensate themselves. In an eye- piece with compound glasses the colours of the star can indeed be lessened; but the small ring would be seen the more co- loured. For other reasons, too, these eye-glasses would not be advisable. The reason why the observations in a transit instrument are capable of so great a degree of exactness, is, without doubt, because the threads are so thin, that they hardly cover the star, or do so for a moment only, and that the space passed within a second of time next to the thread can be divided. If the observations with a circular micrometer were to give a similar exactness, then the circles in the field of view ought to be as thin as those threads, but would require to be illuminated in the dark field of view, because in comets the field cannot be illuminated. I tried to cut with a diamond fine circular lines upon a thin piece of plate glass; and having brought it into the focus of the telescope, illuminated the cut lines in the same manner as I had formerly done in lamp-wire micrometers. But in what- ever way I altered the illumination, there were always small segments only of the cut lines weakly illuminated; viz. those segments upon which the light which came from the lamp fell nearly vertically. It is also the case with the wire-lamp mi- crometer, that the threads are only then illuminated strongest, when the light falls vertically upon them; thus, for instance, the vertical wire can be splendidly illuminated, while the ho- rizontal one is quite unilluminated. By increasing the lamps, which were used for illuminating the cut lines, the object could not be accomplished. I observed, however, that already, with one lamp, the small particles, accidentally adhering to the glass, were illuminated splendidly bright, and had the ap- pearance M. Frauenhofer’s Description of a new Micrometer. 218 ip pearance of stars in the field of view. If therefore the circular lines were composed of small dots, then they would be illumi- nated by one lamp equally at all places. We have however to contend with great difficulties, to make a circle consisting of dots exactly round. I recollected that a line deeply etched in glass by fluoric acid gas, examined under the microscope, consists in its depth of inequalities, and has nearly the same appearance as if it consisted of dots. ‘The circular lines deeply etched in this manner were illuminated sufficiently and pretty nearly equal at all parts, by alamp. ‘The glass on which lines are to be etched is covered for this purpose with a very thin coat of etching ground, on which the lines, intended to be etched, are to be scratched with a steel point. Covering the glass with leaf-gold, instead of etching ground, as is frequently done for etching with gas, is not advantageous for circular micrometers, because the fluoric acid gas acts, next to the scratched line, also beneath the gold, and in etching deep, the polish of the glass likewise suffers in other places. With a brittle etching ground the scratched lines become impure, and the gas, in etching the lines deep, acts next to them beneath the etching ground. With a too soft etching ground the etched lines easily receive unequal strength. The etching ground must intimately cohere with the surface of the glass, and be of such a consistency, that the steel point, in scratching, cuts only fine threads, which repeated practice will teach. If the fluoric acid gas acts too short a time on the glass, then the etched circular ines are illuminated but very weakly by the lamp ; too strong etching, even with good etching ground, makes the lines coarse and rough. Common plate glass is unequally acted upon at different places by the fluoric acid gas. The glass used therefore for lamp-circular micrometers must be very ho- mogeneous. In several sorts of glass, the time which the a¢id takes to act, differs, and some sorts of glass, deep even as they may be etched, never give a circular line, which shall appear in all its parts strong and equally illuminated by the lamp. In order to give the circles made by the scratched lines the degree of exactness that is required, and to scratch upon the same glass many circular lines, which are exactly concentric, I contrived a particular engine, whose description is here su- perfluous ; with it Birbalelints of :003 to 13 inch diameter can be made at any given distance from each other. We have to contend with some difficulties, in finding a con- struction of eye-glasses, which at one and the same position plainly show the inner and outer circular lines in the field of view, and which are so contrived, that. the light from the lamp, 214 M. Frauenhofer’s Description of a new Micrometer. lamp, illuminating the circular lines, cannot come to the eye ; and that the field of view remains dark. In the eye-glasses, which I made for the lamp-circular micrometers, this has been very well accomplished. In order to keep off the light coming from the lamp as much as possible from the eye, a great deal will depend also upon the form of the setting of the eye-glass. The micrometer with which the astronomer M. Soldner made some observations, and who under favourable circum- stances will make more with it, contains circular lines, which follow one after the other, as is represented on a larger scale in Fig. 1. The smallest circular line appears to the naked eye as a small dot, and is only distinguished by the eye-glass. With a higher power, which in a telescope of 60 inches focus magnifies 110 times, 5 circular lines are seen, including the smallest: through the middle eye-piece, magnifying 62 times, 8 circular lines are seen; and with the lowest eye-piece, mag- nifying 45 times, eleven circular lines are seen. As with many circular lines it could perhaps not be correctly judged at the moment how many of the lines the star has cut, and an error might easily take place, I gave to the 5th and 6th, the 8th and the 9th larger distances from each other, than to the rest ; so that it is known in a moment with which circular line the observer is occupied. With the magnifying power of 45 times, the largest circular lines are illuminated somewhat weaker than the rest, and are less plainly seen; for which rea- son the weaker one is used only in great differences of decli- nation, where the stronger oculars cannot be made use of; and also for this reason, that with a less magnifying power the same exactness is not possible as with higher ones, The different circular lines of the above-mentioned micro- meter have the following dimensions, the Paris inch taken as unity : Dimension of I. = -0038 Il. = 0243 III. = -0840 IV. = -:1678 V. = 2513 VI. = °3590 VII. = °4426 VIII. = +5264 IX. = °6338 XX. = +7178 XI. = °8012 These dimerisions I measured with the microscope, with which I determined the breadth of the interstices and thick- ness of the threads of those squares, which appertain to the phae- nomena M. Frauenhofer’s Description of a new Micrometer. 215 nomena produced by the mutual action of bent rays *, so that their exactness cannot be questioned. By the same microscope I also ascertain whether the circular lines be exactly round and concentric. It is only wanted to determine the proportion of the diameters with the microscope. This proportion, and at the same time the value of the dimensions, could be derived with sufficient precision from the transit of a star near the pole, if the telescope was set sufficiently firm. If the propor- tion of the dimensions was determined by the microscope, then it is required only to determine the value of the dimen- sion of one of the largest circular lines, in order to know also the value of the remaining ones. As the circular lines are exactly concentric, the values of their dimensions, which they have at the focus of any object glass, can be determined in many different ways. If the telescope were placed extremely steady, and could be at the same time very sensibly moved, then the determination of the values of the dimensions might be the most simple, by means of the pole-star. For it is only necessary to place this star in the middle of the smallest cir- cular line, and to observe the time of its transit through the other circular lines. But this transit requires much time, for which reason a telescope might not be easily placed sufficiently firm ; nor is it easy for the motions of the telescopes to be suf- ficiently sensible, in order to place a star exactly in the ceutre of the smallest circular line. If the proportion of the dimen- sions of the different circular lines is known, then their value can likewise be derived from the transit of a single determined star, even if it does not pass through the centre. For a star therefore of small declination, if it passes through the centre of the field of view, the greater part of the circular lines in the above micrometer are distant from each other about 10 seconds of time; which time might perhaps suffice to note the observation. As this time is proportionally longer for northerly stars, double the number of circular lines might be made in the field of view, without incurring the danger of being uncertain with which line the observer is occupied. One might, for instance, give equal distances to the first 5 circular lines, from each other, then, for easier distinction, to make the distance from the 5th to the 6th larger; then again 5 in equal distances, &c. With this micrometer one halt of these circular lines could only be made use of in stars of small declination ; because the intervals of time for noting would be too short. As the declination can only be exactly derived from those observations where the star has cut a small segment * See New Modification of Light, &c., by M. Frauenhofer. of 216 M. Frauenhofer’s Description of a new Micrometer. of the circular line (but where there are many circular lines, one of them at least must have an advantageous position), it might even in this respect be desirable to make as many cir- cular lines as is advisable for other reasons. Should even in some of the circular lines the ingress merely have been ob- served, and the interval of time had been too short, in order to observe the egress too, yet in that case the observation is not lost; because the circular lines are concentric, and their distances are known. The circular lines are so strongly illuminated by the lamp, that their light does not vanish, even if'a large star approaches them. In very weak comets, however, this strong illumina- tion might endanger the exactness of the observation. With- out lessening the flame of the lamp, the illumination of the circular lines can be diminished, by putting into the small tube, with which the lamp is annexed to the eye-tube (fig. 2), a smaller one, which contains a diaphram. ‘The oil-vessel a _ of the lamp can in every position of the telescope assume, on an average, a horizontal *situation, partly because it can be turned round the axis 4 of the cylinder, which forms the lamp, partly because the lamp in the small tube, with which it is annexed to the eye-tube, can also be turned. The flame is, in all positions of the telescope, in the axis of the lamp. The light of the lamp, next to the flame, falls upon a convex glass, through which it is thrown upon the micrometer. The oil-vessel can be lifted out of the lamp, by pushing back at the screw c. By the pushing back of this part an opening at the top of the oil-vessel takes place, through which oil may be added. The glass on which the lines are etched, is so placed that the etched surface is turned towards the eye-glass. A re- versed position of this glass produces a disadvantageous re- flexion, and the circular lines are less advantageously illumi- nated. ‘The three different eye-glasses can be screwed to the same frame in which the etched glass is fixed, so that the lat- _ter need not be changed or brought out of its position, while the different magnifying powers are applied. Hach eye-glass has in the front towards the plane-glass a diaphram. of such an aperture that it takes in the necessary part of the field; and betwixt this and the first eye-lens still a second one, through which a part of the light, coming from the lamp, which does not strike upon the circular lines, is intercepted. One might perhaps suppose that, if the etched glass were not perfectly plane, it might have a very detrimental influence upon the observations; but we may only imagine what would take place if this glass was in reality perceptibly concave or P convex ; M. Frauenhofer’s Description of a new Micrometer. 217 convex ; and we shall find, that, if not thick and if it stands at the focus of the object-glass, no detrimental effect can take place. As the eye-piece is not achromatic, the stars become somewhat coloured at the margin of the field; however, they do not change their form when a circular line cuts them, and even small stars do not vanish at the moment of the transit through the illuminated circular line. I have tried to make an achromatic eye-glass, but hitherto I see no possibility of hitting upon one which shall, at the same time that the mid- dle circular lines are plainly seen, show also the outer ones tolerably plain, without moving the eye-glass. As the eye- glasses strongly magnify, every particle which edheres to the cut glass is perceptibly seen, because it is illuminated by the lamp. It is almost impossible to keep the cut glass totally free from dust. Although the illuminated particles appear in the field of view like stars, yet we soon accustom ourselves to their presence, and they are no obstacle to the observation, because they do not change their places, but real stars are al- ways in motion, and can therefore be easily distinguished from those dusty particles. That too much dust should not be suffered to adhere to the glass, is a matter of course. As in all instruments, where seconds of time are of conse- quence, a firm position is the main object, so likewise is this the case here: and nothing ought to be neglected which is capable of producing it. If the micrometer is to give such exact obser- vations as it is capable of, then the place where it is to be put up, must be carefully chosen, every possible draft of air avoided, and the observer must remain, during the transit of the stars, unalterably quiet, without touching the telescope with his eye, which is almost superfluous to mention. For ' this reason, it might be well if the observer did not note the observations himself, because he must change his position for that purpose. A considerable alteration of the instrument, during the transit of the stars, could however be often detected at the calculation of the observations. For determining the relative place of two very near stars, for instance a double star, there might still remain a good deal to be wished for in the described micrometer. In these stars the interval of time from the transit of the one to the transit of the other, is much too short, in order to be observed with any certainty. For this purpose a micrometer, consisting of straight parallel lines (fig. 3), whose distances from each other are exactly known and which cut through one another at an acute angle, which is exactly ascertained, might be very ad- -vantageous. The glass on which these lines are etched can be so turned on the telescope, that the lines which run pa- Vol. 63. No. 311. March 1824. Ee rallel 218 M. Frauenhofer’s Description of a new Micrometer. rallel with d e stand nearly vertical upon the parallel circle of the star; the lines running in the direction fg would therefore be inclined thereto. From the times of transit of the stars through the vertical and those through the inclined parallel lines, the difference of right ascension and declination can be derived with accuracy. To place the lines running in the di- rection d e exactly vertical upon the parallel circle, might not well be accomplished, even if still another line was drawn, of which one knew that it cuts these parallel lines exactly under aright angle. As the distance of the vertical lines from each other, and also that of the inclined ones, in the same manner as the angle under which they cut each other are exactly known, the proportion of the times of transit of a star through the vertical to those of the inclined parallel lines, will make us correctly acquainted with the position of these lines with regard to the parallel circle. The calculation of these obser- vations will always be still more simple, than what is made with the circular micrometer. Even at a transit of both the stars we always obtain several observations, which on an ave- rage give declination and right ascension equally exact, whe- ther their difference of declination be great or small. Where the difference of right ascension is small, as for instance in double stars, the transit of both, indeed, could not be observed through one and the same vertical line; but the observer would for instance observe one at the first vertical line, the other at the second, &e. This lamp vef-micrometer has, amongst others, this advantage; viz. that an alteration of the instru- ment, during the transit of both the stars, can be detected pre- vious to the calctilation. I have given to the parallel lines such a distance from each other, that the distance of the in- clined to those of the vertical ones bears about the same pro- portion, as the cosines of the inclined angle to the radius, in order that about as many transits of the star, through the in- clined as well as through the vertical lines, may be observed. Five lines always have an equal distance only; the 5th is one half more distant from the 6th, than the rest amongst them- selves. From this it is easy for the observer to know with which line he is occupied. I have constructed an engine, with which straight lines can be cut exactly parallel, and to ‘0001 of an inch at equal di- stances. ‘This engine is at the same time so contrived, that the parallel lines can be cut through the others under any given angle, exactly to a minute of a degree. For this net- micrometer the same lamp and the same eye-glasses are used, as to the above-described circular micrometer ; and it is only necessary to screw on the frame with the met, in- stead of that with the circular lines. A BES 4] XXXVI. Notices respecting New Books. The English Flora, Vols. \. and U1. By Sir J. E. Smitru, M.D. F.R.S. President of the Linn. Soc. §c. Se. §ce. 1824. HE public will accept with pleasure this portion of a work - which has been long promised. These two volumes com- prise about one half of the pheenogamous plants, and the author purposes to proceed immediately with the remainder. ‘The preface gives a succinct and masterly outline of the nature of a Flora, confined as it should be to botanical illustration and description, with such remarks concerning the properties of plants as may be new or important; with philosophical views arising from the nature of the subject, tending to the general elucidation of botanical science. A great improvement upon the author’s Flora Britannica is introduced, by combining as much as possible some account of the natural affinities of each genus with the Linnean character. Thus, not only is the in- dividual species pointed out in the clearest way to the student by means of the artificial system, but the natural relations to other species and genera, and much of its history and physio- logy, which constitute the philosophy of the subject. By the plan here adopted, the repetition of the species twice over is avoided. Although English botanists have been conspicuous for their acute search into species, somewhat to the exclusion of more general views, this work, with others of the learned author, will give them a taste for the higher departments of the study, and not leave them satisfied with an acquaintance solely with the individual. If the Flora Germanica of Schrader, a small portion of which has reached this country, be more minutely discriminative in the descriptions, and be aided by some illustrative figures of difficult species, the English Flora of Sir J. I. Smith surpasses all others in its critical department. The descriptions are am- ple for all purposes of distinction, and the diagnostic views greatly assist the inquirer. There is an amenity and candour about the whole work highly creditable to the feelings of the author and to his subject, and he does but exemplify in his own practice what he says is the tendency of all natural science :—“ to enlarge the understanding by a perpetual dis- play of the power and wisdom of God.” The language is accommodated, much beyond what we could have expected, to the merely English reader, who will not be deterred by the Latinity of the nomenclature, adopted by Dr. Hull in his ‘ British Flora,” and by some other au- Ke2 thors. 220 Notices respecting New Books. thors. The typographical arrangement claims no small share of praise ; and the various heads of information under each species catch the eye in a convenient and instantaneous way. Indeed we can suggest no improvement in this department, unless the habitats, as in the Flora Britannica, had been ex- pressed in a different type. A few only of the novelties, which are to be found in peru- sing this work, can now be noticed. Salicornia radicans and JSruticosa are said to be possibly varieties, and most of our best botanists concur in this view. Callitriche autumnalis, which is aquatica y of Fl. Br., is now first admitted on the authority of that keen observer, Dr. Wahlenberg. The lovers of Flora will be glad to see Veronica hirsuta established as British, and for which we are indebted to Mr. James Smith, who belongs to that useful class, the Scotch gardeners. Has the learned author ever noticed the St. Vincent Rock’s specimens of V. hybrida ? One of our lynx-eyed friends always insists that it is distinct from the Humphrey Head plant. The V. Allionzi of Hooker is, with propriety, made a variety of officinalis. Scheenus Mariscus, on the authority of Brown, affords the type of a new genus called Cladium. Fedia, comprehending the old Valeriana focusta (now F. olitoria) and dentata, is immutably established. Scheenus albus and fuscus furnish another new genus, created by Vahl, called Rhynchospora,—the only real Scheenus left aes nigricans. Eleocharis, again, embraces Scirpus palustris an some others allied in habit; but why cespztosus should still be left among the Se7sp7 does not satisfactorily appear. The articu- lated style is the character of the new genus. Cyperus fuscus appears here from Hooker’s Flor. Lond., but its claim to be a native is probably to be suspected. riophorum pubescens is new, from Cherry Hinton near Cambridge. The Grasses have undergone great changes, by the division of the artificial genera, and by a new arrangement of their proximities. The old Phlewm paniculatum is now asperum, which is the more common and appropriate name. _Phalarzs arcnaria is now a Phleum. The genus Tyichodium of Michaux and Schrader, to which our Agrostis canina and setacea were supposed to belong, by habit as well as by character, is not admitted. The total absence of the inner valve does not seem essential, as may be seen in 7. rupestre, which is considered as an indubitable species of this genus. ‘The A. setacea seems scarcely to be known by the continental botanists. It is to Curtis that we are indebted for the first complete establish- ment of this species. His figure and description are, as usual, clear and accurate, and leave nothing to be desired. Withering mistook it for 4. alpina, from which it differs widely in the pani- cle, Notices respecting New Books. 221 ele, and in the genéral roughness. Hudson asserted, that when transplanted into a moistish soil it became canina ; and thus it is y of that author. Perhaps its nearest congener is 4. ru- bra, to which Hudson referred it in his first edition, and of which it is, improperly, made a variety by Wahlenberg. His remark is, “ Var. 6 in Suecia inferiori quoque crescit, et om- nino conyenire videtur cum A. setacea Smith—paniculam satis densam habet. Flosculi vero in utraque iidem, ita et nonnisi varietate a Lapponica differt.” There is this difference, how- ever, between his plant and ours, that the valve of the corolla of the Lapland species is “ apice subintegra subenervis,” whereas the nerves of our setacea are conspicuous, and end in a mucro. ‘Though this difference is but trifling to the eye, it is much more to be depended on than many more obvious ap- pearances. A. mutabilis of Sibth. is rightly rejected as a synonym of setacea. He describes his plant as awnless, “pa- nicula patente,” &c., all of which agrees well with some of the varieties of alba, and not with setacea. There is nothing but his reference to Scheuchzer to favour the idea of his having had that plant in view, whose description and figure, how- ever, are equally applicable to alba. In addition, it may be remarked, that the writer of this has sought in vain for setacea in the habitats mentioned by Sibthorp, and he thinks he may safely affirm, that A. mutadilis is not setacea, but most pro- bably a variety of alba. A new specific character is drawn up for 4. canina, which was left in the F7. Br. in considerable obscurity. The syno- nym of Leers is now added, whose character and description are completely satisfactory. In referring to Withering’s A. vinealis as A. canina, some doubts suggest themselves, for which there is not room in this place. The canina of the 2nd edition of the “ Botanical Arrangement” is probably Lin- neeus’s plant. Panicum, which included a completely artificial assemblage of species, is now divided into Panicum, having P. viride for its type; Cynodon being the old P. Dactylon ; and Digitaria, which is the Cock’s-foot grass. Aira levigata E. B. is here transferred to alpina, after Wahlenberg. Hierochloe borealis (sometimes spelt by the learned President, as if by intention, Hierocle} is a new and curious arctic species.‘ It is a very natural genus of grasses,” as Mr. Brown observes, “ natives of the colder regions of both hemispheres.” It is re- lated in some particulars to Anthoxanthum. Glyceria, com- prising Poa aquatica and its allies, is another well authorized change sanctioned by Mr. Brown. The true Poe are confined to that section which has ovate spikelets. Poa flexuosa is ascer- tained by Schrader to be laxa; subcarulea and humilis are brought back to pratensis as varieties; and ceséa is made a var. : of 222 Notices respecting New Books. of glauca. Poa decumbens, which has always been regarded as an unnatural Poa, is, with Brown, made into a natural genus, Triodia. Sir James E. Smith concurs with Schreber in making Dactylis stricta a Spartina. Festuca cesia, E. B., is brought back to ovina, which will be concurred in; but is not F. tenuifolia good? ‘The absence of the awn is probably a sufficient character joined with the habit. Schrader and Hooker had abolished 2. vivipara, but the President still retains it. Festuca triflora is very properly made a var. of J. gigantea, as F. decidua is of calamaria. It had been thought that this last-named species was confined in England to the North; but that accurate botanist Mr. EK. Forster has lately found it at Harrison’s Rocks near ‘Tunbridge Wells. Bromus pinnatus is again joined with Festuca, as Hud- — son had done before. It is not confined to chalk, but is most abundant on the oolite; and Mr. Greenough says it is very plentiful on magnesian limestone. Schrader and Hooker are followed in B. multiflorus, which turns out to be a different plant from what the #7. Br. had made it. B. pratensis, E. B., and arvensis, E. B. 920, are merged in racemosus. B. squa- mosus most botanists will think ought to be excluded as not English. Long Sleddale in Westmoreland has been ransacked often enough for Stipa pennata, to warrant the assertion that it is not to be found there; and Dr. Richardson, the supposed finder, is of little authority. . Avena planiculmis, a discovery of that extraordinary lucky botanist G. Don, is now alpina. ‘The writer of this has en- deavoured in vain to understand the Arundo epigeios of Schrader ; many of ours auswering much better to his figure of pseudophragmites, and none of them to his figure of epigezos. He relies chiefly on the insertion of the arista. Lottbollia fiiformis is surely not worthy of notice. Zlymus is not con- fined, as the present writer has observed, to chalk; and he would notice, by the by, that the learned President often in- correctly uses the word limestone as synonymous with cal- careous soil. Triticum repens y is treated by many good botanists as a species under the trivial name of marztimum, but it is here regarded still as a variety. Holostewm umbellatum is not made with Hooker a Cerastium; in which most systematic botanists will coneur. et Among the Galia, of most difficult discrimination, are two new ones, cinereum and aristatum, still from Mr. George Don. Any one who would illustrate this difficult family would con- fer great benefit on systematic botany. The foreigners have many more than we have admitted. Sanguisorba media is new from G. Don. For Zpimedium alpinum there are some new habitats. The one on Skiddaw should be ascertained, as.that ; looks Notices respecting New Books. 228 looks as if the plant were truly wild. Mr. Thomas Hutton, the well known guide to the Lakes, never could point the plant out to any of the numerous botanists who went searching for it. Potamogeton cuspidatum of Teesdale is admitted upon the authority of Schrader. Sagina erecta, so different from the rest, is here, as well as by Hooker, called Meenchia glauca. The genus Myosotis, raised lately to some popularity under the name of Forget-me-not, is well illustrated. Three new species are added, M. cespitosa, sylvatica (Ray’s plant), and intermedia. ‘The two first are not uncommon. ‘The author follows Lehman, the great authority in this tribe, in calling rupicola, Ki. B., alpestris. Lithospermum maritimum is the old Pulmonaria maritima. Does it not turn out that most of the habitats assigned to Pulmonaria officinalis are those of angusti- folia? The Echium italicum is very justly excluded. Ray’s plant, brought from Jersey by Joseph Smith, Esq., F.L.S, Justified, as far as the present writer noted at the time, all the changes of synonyms here made ; and in addition he recollects consulting the Sherardian Herbarium to ascertain the Echium ramosius, &c. (Moris. sect. xi. t. 27), and he found it the J ersey plant, and not the ztalicum. It will probably be found here- after to be a good species. Those who love the Primroses, with all their agreeable early associations, will be pleased to find the addition of P. scotica to our Flora. Cyclamen euro- peum, the old Sow-bread, turns out to be hederifolium. Me- nyanthes nympheoides, so aptly termed the F ringed Water- lily, is not, with Professor Hooker, removed to Villarsia. The remark that the trivial name is not meant to compare the plant with a nymph, but with a Nymphea, is obviously just. The pretty Anagallis cerulea, which has no specific cha- racter, though all the beauty, of a noticeable species, is still re- tained. Campanula persicifolia is an addition. Viola flavicornis is made out of canina y. Is not Sibthorp’s V. arvensis as good as any? A very curious instance of irritability is recorded under Verbascum pulverulentum : if the stems be smartly struck three or four times with a stick, all the flowers then open will, in a few minutes, throw off their corolla, the calyx closing round the germen, so that after eight or ten minutes none will remain on the plant. Chironia has disappeared, all our species being true Erythree. FE. latifolia is well established as a species, being the second var. of Chironia Centaurium in Fl. Br. So much has occurred to interest us in perusing the first volume, that we have lengthened our observations much be- yond our original intention. ‘The second volume will furnish another paper for the next Number. Recently 224 Royal Society. Recently published. Dr. Forster has just published a work, entitled ‘The Perennial Calendar,” being a sort of compendium of the na- tural history of each day in the year, arranged according to the days in the Calendar, and interspersed with numerous notices of popular customs and superstitious ceremonies and rites which belonged anciently to particular seasons, or to festivals and days. The work was the amusement of his lei- sure hours many years ago when a student, and having been increased by the addition of numerous essays and observations by his friends, has been arranged in a popular form and published. It contains among other things, notices of the particular days on which certain plants have been found to flower in the climate of London; deduced from journals of twenty or. more years regular observation. ‘The whole forms a very thick octavo volume. In the Press. Mr. R. Phillips’s Translation of the New Pharmacopeia Londinensis, with copious Notes and Illustrations, will appear in a few days. ANALYSIS OF PERIODICAL WORKS ON NATURAL HISTORY. Curtis's British Entomology. No. 3. contains the following subjects : Pl. 11. Molorchus minor, a curious insect, of which Linneeus said, it had the antennz of a Cerambyz, the legs of a Leptura, and the elytra of Forji- cula.—Pl. 12. Lycena dispar (the large copper Butterfly), a most splendid species which has been discovered, in some abundance, in Huntingdonshire. —PI. 13. Humenes atricornis, a new genus to this country, discovered in Hampshire by the Rev. Wm. Kirby: this genus of Hymenoptera is found as far east as China.—P]. 14. Hemobora pallipes, a perfectly new genus of the curious order Omaloptera of Leach, found by Mr. Samouelle in the New Forest, Hants, where the forest fly abounds upon the horse to an astonish- ing extent; and this possibly may be attached to the deer, as those animals are found in every part of that neighbourhood. XXXVII. Proceedings of Learned Societies. ROYAL SOCIETY. Feb. 26.— A SERIKS of observations were presented “ On nearly all the principal Fixed Stars between the zenith of Cape Town, Cape of Good Hope, and the South Pole;” by the Rev. Fearon Fallows, M.A. F.R.S., Astronomer at the Cape of Good Hope. A paper was read “On the different Degrees of Intensity of the local Magnetic Attraction of Vessels in their different Parts;” by George Harvey, M.G.S. M.A.S. of arch Geological Society. 225 March 4.—A letter to the President was communicated from Sir E. Home, Bart. V.P.R.S., entitled ‘Some curious Facts respecting the Walrus and Seal, discovered in the Examination of Specimens brought by the late Expeditions from the Polar Circle.” ' A paper was also read, entitled “ Some further Particulars of a Case of Pneumato-thorax, by John Davy, M.D. F.R.S.” March 11.—A paper was read, “On the Parallax of« Lyre; by the Rev. John Brinkley, DD. F.R.S. &c.” March 18.—A_ paper was read, entitled “ An Account of Experiments on the Velocity of Sound, made in Holland ; by Dr. G. A. Moll, and Dr. A. Van Beck.” March 25.—A communication was read from L. W. Dillwyn, Esq. F.R.S. On the geological distribution of Fossil Shells. A letter was likewise read trom Thomas Tredgold, Esq. Civil Engineer, to Thomas Young, M.D. For. Sec. R.S., “ On the Elasticity of Steel at various Degrees of Temper.” GEOLOGICAL SOCIETY. Feb. 20.— A notice was read on the Megalosaurus, or Great Fossil Lizard of Stonesfield, near Oxford; by the Rev. W. Buckland, F.R.S. F.L.S. President of the Geological So- ciety, and Professor of Mineralogy and Geology in the Uni- versity of Oxford, &c. &c. The author observes that he has been induced to lay before the Society the accompanying representations of various por- tions of the skeleton of the fossil animal discovered at Stones- field, in the hope that such persons as possess other parts of this extraordinary reptile, may also transmit to the Society such further information as may lead to a more complete re- storation of its osteology. No two bones have yet been dis- _covered in actual contact with one another, excepting a series of the vertebre. From the analogies of the teeth they may be referred to the Order of the Saurians or Lizards. From the proportions of the largest specimen of a fossil thigh-bone, as compared with the ordinary standard of the Lacerta, it has been inferred that the length of the animal exceeded forty feet, and its height seven. Professor Buckland has therefore as- signed to it the name of Megalosaurus. The various organic remains which are found associated with this gigantic lizard form a very interesting and remarkable assemblage. After enumerating these, the author concludes with a description of the plates and observations on the anatomical structure of such parts of the Megalosaurus as have hitherto been discovered. March 5.—'he paper entitled ‘* Outline of the Geology of the South of Russia,” by the Honourable William T, H. Fox Strangways, M.G.S., was concluded. Vol. 63. No. 311. March 1824. Ft The 226 Geological Society. The term Steppe is applied to vast tracts of country in the E. and S.E. of Europe. It is neither a heath, nor a moor, nor a down; wold would give the best idea of it in English, and it is given by the Russians to any waste land which is neither mountainous nor wooded. The Russian Steppes are bounded on the west by the Carpathian chain of Transylvania and the Banat of Temesvar; on the S. by Mount Hemus, the Tauric Chersonese, and Caucasus; on the E. by the Oural mountains to beyond the Caspian Sea and the sea of Aral; vaguely to the N. by a line from the mouth of the Kama to the Dniester on the frontiers of Podolia and Kherson. Their length is about 2000 miles, breadth 900. The soil is similar throughout; the geological structure very different. A trough or basin stretching across from Perecop to the ’ Caspian, and thence beyond the sea of Aral, forms a natural division of the Steppe into the N. and S. High Steppe; this trough or basin Pallas and others well describe as the low sandy saline steppe, the two former, as the high rich calca- reous and granitic steppe. The Northern High Steppe admits of five divisions: 1. Steppe of red marl, salt and gypsum, lying on both sides the Volga above the reach of Samara. 2, Steppe of Saubof and the middle Volga, from Samara to Tzaritzin; its northern part consists of the white central limestone, its southern of sandstone which connects it with the steppe of the Don. 3. Northern calcareous steppe of the Don is composed of sandstone to between Cherkask and the mouth of the Donetz; here commences an immense tract of a peculiar modern shelly limestone; the steppe limestone probably extends across the Ukraine, and is connected with the calc. gross. of Volhynia and Gallicia. 4. S. and S.E. of this occurs the primitive or granitic steppe, a singular instance of a flat tabular granitic country connected, according to Pallas, with the primitive - range of the Carpathians, passing the Dniester at Doubosar, and traversing Moldavia. 5. Middle calcareous steppe, of steppe limestone separated by a sandstone from the preceding ; this is a prodigious mass extending throughout Wallachia, Bessarabia, the south of Moldavia, and Government of Kher- son. ‘The trough or basin before alluded to forms the steppe of the old sea, which involves the singular problem of the connexion and extension of the Caspian and BlackSeas. To the south of this lies the southern calcareous steppe, compre- hending the Crimea, and stretching to the foot of Caucasus, is composed of steppe limestone resting on calc. gross. The high steppes, from the occurrence of marine plants and other causes, have been supposed to have once formed a vast sea; but Geological Society. 227 but their height, in some places 700 feet above the Black Sea, and 1000 feet above the Caspian, precludes the possibility of this. The author, after enumerating and describing the series of the above-mentioned beds, and their accompanying fossils, concludes with remarks on the probable extension of the Caspian Sea, and the sea of Aral, and their connexion with the Black Sea by means of the low steppe. A letter from Mrs. Maria Graham to Henry Warburton, Esq. V.P.G.S., was read, giving an account of the effects of the Earthquakes which visited the coast of Chili in 1822 and 1823. The first shock by which the towns of Valparaiso, Melipilla and Quillota were nearly destroyed, was felt at a quarter past 10 o'clock on the evening of Tuesday the 19th of November 1822; and from this time continual shocks were felt daily until the 18th of January, when the authoress ceased to reside in Chili. These shocks are said not to have terminated wholly so late as September last. The sensation experienced during the more violent shocks was that of the earth being suddenly heaved up in a direction from N. to S., and then falling down again, a transverse motion being now and then felt. On the 19th of November a general tremour was felt, and a sound heard like that of vapour bursting out, similar to the tremour and sound which the authoress observed while standing on the cone of Vesuvius during the jets of fire at the eruption of 1818. In all the alluvial valleys in the neighbourhood of Quintero, 30 miles N. of Valparaiso, quantities of water and sand were forced up, which covered the plain of Viiia a la Mar with cones or hillocks four feet high. The promontory of Quintero, consisting of granite covered by sandy soil, was cracked in various directions down to the sea; and the cracks occasioned by the earthquake in the gra- nite on the beach were parallel to the more ancient rents in the same rock. On the morning of the 20th, after the first earthquake the whole line of coast from N. to S. to the distance of 100 miles was found to have been raised out of the sea; the elevation at Quintero being about four feet, that at Valparaiso about three feet, beds of oysters and muscles, adhering to the rock on which they grew, being seen lying dry on the beach. Similar lines of beach with shells are found parallel to the coast to the height of 50 feet above the sea, which probably have been occasioned by earthquakes which have in former years visited Chili. The earthquake of the 19th was felt along the coast to the distance of 1400 miles at least. rf2 LINNEZAN 228 Linnean Society.» LINN.EZAN SOCIETY. March 2.—An additional portion of Mr. Vigors’s paper crt the Orders and Families of Birds was read this evening, as well as on the 16th; it is not however concluded. March 16.—Among the presents received were the first two volumes of the valuable English Flora, just published by the much esteemed President of the Society. - The following communications were read : Description of Erythrina Secundiflora. By Don Felix Avel- lar Brotero, Emeritus Professor of Botany in the University of Coimbra, For. Mem. of the Society. On the insect called Ozs/ros by the ancient Greeks, and Asilus by the Romans. By W. S. MacLeay, Esq. F.L.S. Communicated by the Zoological Club of the Linnean So- ciety. In this paper, which may interest the lovers of classi- cal antiquity as well as of natural history, Mr. MacLeay has produced many interesting proofs that the @istrus of the an- cients, “ cui nomen Asilo Romanum est, (stron Graii vertére vocantes,” (Virc. Geor. IL.) was not the insect to which this name is now given, but a Tabanus. Olivier first observed that it was different from the Cistrum of the moderns. Pliny uses the name Tuabanus for the Mua, which Aristotle says is nearly related to Hsfrus, both being sumgocbevxevrgx; it cannot therefore be the modern (Estrus; he also says that both are bloodsuckers, which agrees with the Linnzean Fabani, but is wholly inapplicable to the modern Cistrus. As the insect is too well known for its name to have been forgotten or misapplied, there can be little doubt that the Latin Tabanus, the Italian Tabano, Spanish Tavano, and French Taon are identical, which latter name Mouffet gives as the same with the English Breese*, Clegg and Clinger, mentioned by Shakspeare, who speaking of Cleopatra, says : * The Brize upon her, like a cow in June, Hoists sail and flies.’ Some elucidation is also brought from Homer, and the Pro- metheus of AXschylus, and it is observed that Virgil describes the Aszlus or Gistrus as abundant and acerba sonans, whereas * This name appears to be of great antiquity in all the Teutonic dialects. The Anglo-Saxon has Bnuoya, [Ital. Brissio], and Bnimya, which latter Junius gives from one of his ancient glossaries D ; and Skinner says “ apud Higginium solum occurrit.’ They render Brie and Griese, Hstrwm, Asilus, and Tabanus ; as does Kilian the Belgic Bremme and Bremse, In the Suio-Gothic we find Bromg, which Ihre explains by crabro; as our Ailfric renders Qstrus beap hy pnevce— Epi. our Astronomical Society. 229 our Cistrus bovis is a rare and silent* insect. They were first confounded by Valisnieri, who has been followed by Martyn and others. It is inferred that Aristotle did not even know the latter, from his assertion that no dipterous insect has a sting behind. —_——_ ASTRONOMICAL SOCIETY. March 12.—The papers read at this meeting of the Society were as follows: A letter from Sir Thomas Brisbane, Governor of New South Wales, to F. Baily, Esq., accompanied by Mr. Rumker’s ob- servations of the Summer Solstice 1823 at Paramatta; the re- sults of which are, — For the mean obliquity of the Ecliptic 23° 27’ 44°39 For the latitude of the place of observation 33° 48’ 4261 Also the mean of twelve months’ meteorological observations made at Paramatta between May 1822 and May 1823. A letter from Professor Schumacher of Altona, including Mr. Hanson’s computations of the elements of the comet of 1823—4, from observations made in the month of January 1824. Two letters from Mr. Taylor jun. of the Royal Observa- tory, Greenwich; the first containing the elements of the same comet as computed by himself from the Greenwich observa- tions of January 1824, using Boscovich’s method ; and the second, a comparison of anticipatory ephemerides of the places of this comet, from the elements computed severally by Schu- macher, Carlini, Dr. Brinkley and himself, with the Greenwich observations. On the Rectification of the Equatorial, by J. F. Littrow, Director of the Imperial Observatory at Vienna. In this paper the author directs his attention to those errors only which de- pend upon the placing and use of the instrument, which the observer himself must either be able to obviate or allow for; and he therefore enumerates the greater part of them, and points out meaus for their rectification. On the Utility and probable Accuracy of the Method of de- termining the Sun’s Parallax, by observations on the planet Mars near his opposition; by Mr. Henry Atkinson, of New- * Thre and others derive the Teutonic names roms, Gremse, &c. from bromina, brummen, bremmen, murmurare, sonitum edere, but Wachter prefers tracing them to bremen, pungere: from which he also brings —“frem, fram, a thorn (from Otfrid, a writer of the ninth century) : brein, brom, rubus :—brem-beren, bramble : brem, genista; A. S. bpom, broom. breme, fremse, crabro, insectum aculeatum, A. S. bpimya ap. Benson. non a Psu fit, nec a Srumimen, bombum edere, sed a bremen, pungere. Inde ross-bhrem, musca equis infesta, estrus, asilus, tabanus.’”’ Probably therefore all the names have a similar origin—Osegos from Oizos, sagitta, and Gad-fly, q. Goad-fly, A. 5. Gaan, za”, stimulus, cuspis, goad ; Island. gadda, pungere.— Epix. castle- 230 Curious Astronomical Fact. castle-upon-Tyne. In this paper the author shows that in a series of observations on Mars, taken with good instruments used in north and south latitudes, the probability of error is very small; and as the synodical revolution of Mars takes place in about 780 days, that planet will be 23 times in op- position before the next transit of Venus on the 8th December 1874, nce he infers that if careful corresponding observa- tions are made on each of those 23 oppositions, the probable etror would be reduced nearly 4°796 times. The author con- eluded his paper by describing what he regards as the best means of carrying this method into effect. A new annular Micrometer by Frauenhofer was submitted to the inspection of the Meeting by Mr. Francis Baily: but as this instrument is described at page 177 of our present Number, it is unnecessary to give any further account of it in this place. XXXVIII. Intelligence and Miscellaneous Articles. CURIOUS ASTRONOMICAL FACT. HE eighth volume of M. Bessel’s Observations (for the year 1822) is arrived in this country. In the preface to that work there are recorded some singular facts relative to the habits of observing, by different astronomers; which we consider worthy of particular consideration. It is known to our astro- nomical readers that in the Greenwich observations for 1795, page 339, Dr. Maskelyne has the following remark : “ I think it necessary to mention that my assistant, Mr. David Kinne- brook, who had observed the transits of the stars and planets very well, in agreement with me, all the year 1794, and for a great part of the present year (1795) began, from the begin- ning of August last, to set them down half a second of time later than he should do, according to my observations: and in January of the succeeding year (1796), he increased his error to 8 tenths of a second. As he unfortunately conti- nued a considerable time in this error before I noticed it, and did not seem likely ever to get over it, and return to a right mode of observing, —therefore, though with reluctance (as he was a diligent and useful assistant to me in other respects), I parted with him.” Dr. Maskelyne then proceeds to state the manner in which the discordancies were discovered, and points out some useful hints to those who are much engaged in this branch of practical astronomy. M. Bessel Curious Astronomical Fact. 231 M. Bessel has met with a similar circumstance at the ob- servatory at Konigsberg. During the visit of the late Dr. Walbeck to that place in the winter of 1820-21, these two astronomers instituted a set of comparative observations on the following stars: 954 Mayeri x Piscium ¢ Aquarii 971 Mayeri y Piscium xxlil. 136 Piazzi —— 147 - 962 Mayeri 979 Mayeri The right ascensions of these stars were observed by them alternately, with the same instrument, for several days; and the result was (taking a mean of the whole number of obser- vations) that Dr. Walbeck observed them 1”.041 in time later than M. Bessel. The observations were made with the me- ridian circle of the observatory, and with a power of 182, We have not room, in this extract, to give more than the re- sults: the detail of the observations occupies several folio Pages in the work above alluded to. e then proceeds to mention some comparisons that were made with M. Argelander of Abo, by which he finds that this astronomer observed the right ascensions of several stars in the constellation Gemini, 1”.223 in time later than M: Bessel. The comparisons made between Dr. Struye and M. Bessel are the most singular: in 1814 the difference was 0”.044; in 1821 it was 0".799; and in 1823 it was 1”.021. By a direct comparison of the culmination of « Piscis Australis on Nov. 13, 1820, the difference was 0.68. Other comparisons were afterwards made between the ob- servations of Dr. Struve and Dr. Walbeck ; and between Dr. Struve and M. Argelander *: and the result of the whole is shown in the following table; where the names of the above- mentioned observers are denoted by their initial letters. B—W= —1".041 —0".044 in 1814 B—A = —1 .223 Teed ae .680 1820 S—W= —0.242 ~~ —O .799 1821 S—A = —\) .202 al OT 1823 From some experiments which were afterwards made, M. Bessel seems to think that a part of this difference may arise from the peculiar mode, which each observer may adopt, of counting the time by his ear, whilst he is watching the motion of the star with his eye. For, by trying a half-second pendulum clock, some of these differences vanished; and * The detail of these experiments is also given by Dr. Struve himself, in the 3rd vol. of the Dorpat Observations, pages L and 42. others 232 Opposition of Mars with the Sun. others were considerably reduced. The subject however de- mands further illustration and inquiry; as it is one of consi- derable importance when comparing the observations of dif- ferent astronomers; and even of different observers at the same observatory. Besides a detail of these singular phenomena, the volume contains, 1° a determination of the scale of the barometer used at the observatory: 2° observations to determine the refrac- tion near the horizon: 3° a new table of corrections for that purpose: 4° the usual daily observations of the observatory ; amongst which we observe the transits of those stars which are pointed out by M. Schumacher as culminating about the same time as the moon: and lastly above seven thousand addi- tional stars, observed in zones, agreeably to the plan laid down in the former volumes; together with the elements for their reduction. The present volume has reached this country much more early (even by many months) than usual: it has in fact arrived before the presentation copies intended for the public societies. This unusual expedition must be attributed to the exertions and activity of Mr. Bohte, bookseller, of York-street, Covent Garden; who is determined, as much as possible, to remove the impediments which obstruct the early transmission of Ger- man books to this country. M. PASQUICH AND M. KMETH. _ A scandalous attack has recently been made on M. Pas- quich, the venerable director of the observatory of Buda, by his assistant M. Kmeth; and which has unfortunately been circulated in many respectable journals. The latter accuses the former of having forged the observations of the observa- tory: that is, in fact, of giving to the world a statement of ob- servations that were never made. Some of the principal as- tronomers on the continent have taken up the subject, in order to convince the world of the innocence of M. Pasquich. Amongst those who have come forward on this laudable oc- casion are MM. Gauss, Olbers, Bessel, Encke and Schu- macher. To the Editors of the Philosophical Magazine and Journal. OPPOSITION OF MARS WITH THE SUN. Gosport, March 25th, 1824. As the announcement of the opposition of Mars must have excited some curiosity among our astronomers, and as cor- responding New Orrery.— Aérolites. 233 responding observations on the place of this planet in the northern hemisphere, may be found useful with those that may be made in the-southern hemisphere, I therefore beg to send you the result of some observations that I have made respect- ing the place of his opposition with the sun. At 8 o’clock this evening Mars was distant from y Virginis 3° 24’ 15”, and from y Virginis 2° 33’ 45”; from which, and with recent obser- yations made on his daily motion towards stars lying nearly in his path, I make the place of Mars at his opposition with the sun this morning 6% 5° 3’ 40” of longitude, and latitude 1° 12’ 30” north; or -R185° 3' 40”, and declination 1° 12’ 30” north. This will differ, but not materially, from what may be ascertained of the place of this planet in the Nautical Alma- nac for 1824; and not having used a micrometer, for want of stars situated nearer to the planet,—only a good sextant,—I am not certain of extreme accuracy: however, the above result will be found near the truth within a few minutes either way. Yours &c. WitiraMm Burney. NEW ORRERY. Mr. B. M. Forster of Walthamstow has just invented a pendent orrery to represent the solar system. It consists of globes, fixed to horizontal rods, and suspended by means of catgut, which twisting or untwisting itself slowly, as the cir- cumjacent air dries or moistens, produces the revolutions of the imitated planetary bedies, the distances of the globes which represent the planets being calculated to correspond with those of the planets themselves. Mr. Forster considers the machine as capable of great improvement, so as to be able in time to represent the whole of the planetary system. The catgut strings which suspend the globe twist themselves hygrometrically by being brought into a dry room from a moist one. AEROLITES. The subjoined notice has appeared in the newspapers; but no information on the subject has transpired from more au- thentic sources: — A letter from Molinella, in the Legation of Bologna, of the 6th of March, says, ** Within the last few days a great number of meteoric stones have fallen in the neighbourhood of the village of Arenazo. The largest of these stones is twelve pounds in weight. Its fall was preceded by claps of thunder of extreme violence, accompanied by wind, a phenomenon which much astonished the inhabitants of the country. The largest aérolite has been taken to the museum of Bologna.” Vol. 63. No. 311. March 1824. Ge 234 Coal. ANTHRACITE OF SCHUYLKILL IN PENNSYLVANIA. We extract the following from the New York Evening Post for the 30th of June last: Coal.—We are pleased to find that there is a rational prospect of this city being supplied, during the ensuing winter, with’ coal from the extensive mines which are now working in the great Schuylkill coal range of Pennsylvania.— Philadel- phia has long enjoyed this advantage, and the effect there has been to reduce the price of wood at least one third. New Jersey appears to be following the example, by making ar- rangements for the transportation from Philadelphia of the Lehigh coal, which is said to have produced a saving on one trial of 50 per cent. Efforts are likewise making in this city to obtain sales for this article. When we know, as we do, that the Lehigh coal sends out nearly doule the heat of the Liverpool coal, and will burn considerably longer, the pro- priety of its introduction to this city, in preference to the im- ported coal, cannot be questioned. Still we understand that there is a coal dug from the same range of mountains, called the Schuylkill coal, which we have reason to believe is superior to the Lehigh coal, and which brings in Philadelphia five cents more per bushel. The Schuylkill coal belongs to a company in this city, recently incorporated by the legislature; and we are informed it is the intention of the directors to bring 5000 chaldrons of this coal into our market next fall, with the double view of profit and to make it more generally known, preparatory to a full supply the ensuing season. We are at all times ready and willing to encourage the improvements of neighbouring states; but certainly, when these come in competition with the enterprize of our own citizens, it cannot be thought invidious, or even unreasonable, if we should give a preference to the latter; the more especially when we aie satisfied, as in this instance, that that preference is founded on general utility. That the Schuylkill coal is superior to the Lehigh coal, we have had no opportunity of determining by actual experiment; but we have the testimony of those in its favour who are well skilled in these matters, and who, from having used both in various ways, have decided in favour of the former. From this source we learn, that no just and ade- quate conception of the Schuylkill coal can be formed from those specimens of the Susquehannah and Lehigh coal, which have been exhibited in New York. The Schuylkill coal is lighter, purer, and more inflammable. In appearance it is bright and glossy, and often beautifully iridescent. It does not pulverise and throw off a begriming dust, like the common : coal. Voyage of Discovery. 235 coal. It is all taken out in large masses, and when broken up, which is necessary to prepare it for the grate, it does not pulverise, but separates into small pieces of curved or prismatic forms. It ignites with perfect facility; burns with a small flame, but with a most vivid and intense heat, leaving an ash small in quantity and white like that of hickory wood. It has no sulphur and no smell. Having no bitumen, it creates no smoke or soot. The permanence and durability of this coal is as astonishing as the strength and vehe- mence of its heat, which circumstances render it the most economical and cheap fire that can possibly be found. These. peculiar qualities of this coal are not only established by the general voice of Philadelphia and the counties on the Schuyl- kill, but are attested by the published statements of the Board of Direction of the Schuylkill Canal Company, composed of gentlemen of the highest distinction and character.—The state, that from ‘‘ repeated experiments,” it is found that ‘ one bushel of Schuylkill coal goes as far as three of Liverpool ; and that ten bushels are equal to a cord of the best oak wood.” The purity of this coal is without example or parallel, being 97 parts out of a 100 pure carbon. Hence itis perfectly and admirably fitted for certain valuable purposes, to which the common coal cannot be applied without a tedious and ex- pensive process of preparation, as in smelting and air furnaces, in breweries, and in kitchens, where it is used for cooking, and answers admirably. In melting iron ore and iron, besides requiring but half the quantity of coal, and saving much time, it improves the quality of the iron—a matter of the highest im- portance—renders it more closely textured, tougher and more malleable. a VOYAGE OF DISCOVERY. Accounts dated in May last have just been received in Paris from the French maritime expedition of discovery com- manded by Captain Duperrey. They contain some interest- ing details on nautical and magnetical observations, and an- nounce the discovery of four islands in what the French call the Dangerous Archipelago, to which they have given the names of Clermont-Tonnere, Lostanges, Angier, and Frennet. The inhabitants could not be induced to have any intercourse with the voyagers. Driven thence by stress of weather, they proceeded to Otaheite, where they witnessed the happy change that has taken place in the morals of the natives since the in- troduction of Christianity. Idolatry, human sacrifices, poly- gamy, and child-murder, are now unknown among them; and many exhibit great fervour in the profession of Christianity. Gg2 The 236 New Analyses of Minerals. The following aNaLYsES OF miNERALS are extracted from late numbers of various German and French journals. Streifenspath. Bernhardi and Brandes. Carbonic acid 4.2°500 Lime 53°66] Magnesia cre aie aOr oo Oxide of iron 1°376 Oxide of manganese —_0°308" Water 0°250 Or, 98°687 Carbonate of lime 94°4524 Carbonate ofmagnesia 12240 Protocarbonate efi iron 2°8000 Carbonate of manga- nese Bug 0°4.995 Watered quis 0°2500 99°2259 Calcareous Garnet of Lindbo. Fisinger. Silica 37°55 Peroxide of iron . $1535 Lime J 26°74 Protoxide of manganese 4°78 100°42 Pitchstone of Meissin. Du Meni. Silica 73:00 lumina 10°84 Protoxide of iron 1:90 Lime 1:14 Soda 1°48 Volatile matter 9°40 97°76 Rubellite of Rozena, in Mora- via. Gmelin of Tubingen. Boracic acid | 5744 Silica SPE D7 Alumina 36°430 Oxide of manganese —_6*320 Lime 1:200 Potassa J O-4O5 Lithia PS het kle Lean 2°043 Volatile matter... 1°313 Aluminite, from the mountain of Bernon, near Epernay (dela Marne). Lassaigne. Alumina 39°70 Sulphuric acid 20°06 Water - + 89°94 Sulphate of lime. . 30 10000 Schorl of Eibenstock in Saxony. Gmelin of Tubingen. Boracic acid . 1:890 Silica 33°048 Alumina 38°235 Protoxide of ircn 23°857 Soda with Poiassa . 3°175 Lime, with a trace of magnesia 0°857 101°062 Semi-opal, from Quegstein (Siebengebir ge): Brandes. Silica 86:000 Protoxide re iron 2°54.0 Subsulphate of do. . 0.843 Alumina 3 0°500 Carbon 0:032 Water 9°968 99°883 Ditto, with a woody texture, from Obercassel. Brandes. Silica 93-000 Alumina 0:250 Oxide of iron 0°375 Subsulphate ofdo. . traces Water 6°125 99°750 Lepidocrocite : Siebengebirge: Brandes. Oxide of iron . §8:00 Oxide of manganese. 0°50 Silica 0°50 Water 10°75 99°75 Universities in the Netherlands.—Standard Weights. 237 UNIVERSITIES IN THE NETHERLANDS, The Report just laid before the States General of the King- dom of the Netherlands by the Minister of Public Instruction, gives the following account of the present state of the Univer- sities: —** At Louvaine the most laudable efforts are made to form good philologists, who may one day be the ornament of the Athenées and Colleges in which they may be placed. The clinical department of midwifery has received a very useful extension. At Liege they apply themselves particularly to modern history under a political point of view. The study of the law also, as well as other branches of science, is very flourishing. The legal part of medical education is attended to with great care. At Ghent nothing is neglected, which can tend to unite the cultivation of the fine arts and the sci- ences. The mathematical instruction is excellent; several excellent scholars have already left the schools. At Leyden, the instruction preserves its ancient reputation, and Oriental literature is there making great progress. At Utrecht the study of Greek and Latin is the favourite pursuit; and at Groningen, no expense is spared to improve the Clinical Hospital, and to form a brilliant Academy.” At the end of the Report, the number of Students in the six Universities of the Kingdom is given, and in November they amounted to 2,127; 1,058 belonging to the Southern Provinces, and 1,069 to the Northern. CABINET OF STANDARD WEIGHTS. The commercial and scientific world will learn with satis- faction that the standard weights of foreign countries, which were some time since transmitted to the British Government, and compared with English Standards, have been lately de- posited at the London Mint, in a commodious cabinet con- structed for the purpose, where they are to be carefully pre- served for permanent reference. ‘This National collection is the first of the kind ever made on a great scale, though long considered a desideratum. Its utility, which has been already extensively proved, may be further experienced when any of the standards in use, whether English or Foreign, shall become worn or impaired. he following account of this important collection is in- scribed on the cabinet :— “ The foreign weights here deposited, having been duly verified, were transmitted to London, in the year 1818, by the British Consuls abroad, in pursuance of a general plan, for comparing the weivhts, measures, and moneys of all trading countries, by official experiments on verified standards. « The 238 List of New Patents. «‘ The experiments were made by Robert Bingley, Esq., the King’s Assay Master of the Mint; and the calculations by Dr. Kelly, who planned and conducted the general compari- son, and in 1821 published the Results in the Universal Cam- bist, under the sanction of His Majesty’s Government. “The undertaking was originally patronized and recom- mended by the Board of Trade. The standards were pro- cured from abroad by circular letters issued by Viscount Castle- reagh and Earl Bathurst, Secretaries of State for the Foreign and Colonial Departments; and the whole plan was essentially promoted by Lord Maryborough, Master of the Mint.” DEATH OF MR. BOWDICH, THE AFRICAN TRAVELLER. We lament to state the decease of this accomplished travel- ler and naturalist, which took place on the 10th of January, at St. Mary’s River in Gambia, Africa, in consequence of his over-exertions in making a survey of the river. A widow and three orphans survive him, who are altogether unprovided for ; and we take this opportunity of announcing that a work which Mr. Bowdich completed prior to his death, entitled “* Excur- sions in Madeira and Porto Santo,” will be published by sub- scription for their benefit. A prospectus of it, we believe, will shortly be issued. LECTURES. Mr. John Edward Gray’s Course of Lectures on Natural History and Materia Medica, will commence in the middle of April; they will be illustrated with numerous specimens, prac- tical demonstrations and excursions, which he has found to be the only plan by which the pupil can be quickly furthered. LIST OF NEW PATENTS. To Abraham Henry Chambers, of New Bond-street, Middlesex, esq., for his improvements in preparing and paving horse- and carriage-ways.—Dated 28th February 1824.—6 months allowed to enrol specification. To Richard Evans, of Bread-street, Cheapside, London, wholesale coffee- dealer, for his method or process of roasting or preparing coffee, and other vegetable substances, with improvements in the machinery employed; such process and machinery being likewise applicable to the drying, distillation, and decomposition of other mineral, vegetable, and animal substances ; to- gether with a method of examining and regulating the process whilst such substances are exposed to the operations before mentioned.—28th Feb.— 6 months. To John Gunby, of New Kent Road, Surry, sword and gun manufacturer, for his process by which a certain material is prepared and rendered a suit- able substitute for leather.—28th February.—-6 months. To List of New Patents. 239 To John Christie, of Mark Lane, London, merchant, and Thomas Har- per, of Tamworth, Staffordshire, merchant, for their improved method of combining and applying certain kinds of fuel.—28th February.—6 months. To William Yetts, of Great Yarmouth, Norfolk, merchant and ship- owner, for certain apparatus to be applied to a windlass.—28th February. —2 months. To James Wright Richards, of Caroline-street, Birmingham, Warwick- shire, metallic hot-house maker, for an improved metallic frame and lap applicable to all hot-houses, green-houses, horticultural frames and glasses, sky-lights, and other inclined lights and glasses.—28th F ebruary.—6 mon. To William Greaves, of Sheffield, Yorkshire, merchant, for certain im= provements on, or additions to, harness principally applicable to carriages drawn by one horse.—28th February.—2 months. é To William James, of Westminster, Middlesex, land-agent and engineer, for certain improvements in the construction of rail- and tram-roads or ways, which rail- or tram-ways or roads are applicable to other useful purposes,— 28th February.—6 months. To Maurice De Jongh, of Warrington, Lancashire, cotton-spinner, for his mode of constructing and placing a coke oven under or contiguous to steam or other boilers so as to make the heat arising from making coal or other intense combustion in the said oven subservient to the use of the boiler instead of fuel used in the common way, and to exclude such heat from the boiler when required without detriment to the operations of the oven. —28th February.—2 months. To Charles Bagenell Fleetwood, of Parliament-street, Dublin, gent., for his liquid and composition for making leather and other articles waterproof, — 28th February.—6 months. To Joel Spiller, of Chelsea, Middlesex, engineer, for his improvements in the machinery to be employed in the working of pumps.—6th March.—4 months. To John Heathcoat, of Tiverton, Devonshire, lace-manufacturer, for his method of manufacturing certain parts of the machines used in the manu- facture of lace commonly called bobbin-net.—9th March.—6 months. To John Heathcoat, of Tiverton, Devonshire, lace-manufacturer, for his improvements in machines now in use for the manufacture of lace com- monly called bobbin-net, and a new method of manufacturing certain parts of such machines. —9th March.—6 months. To John Heathcoat, of Tiverton, Devonshire, lace-manufacturer, for his economical method of combining machinery used in the manufacture of lace, in weaving, and in spinning, worked by power. — 9th March.— 6 months. To William Darker Mosley, in the parish of Radford, N. ottinghamshire, lace-manufacturer, for certain improvements in the making and working of machines used in the manufaciure of lace commonly called bebbin-net.— 10th March.—6 months. To William Morley, of Nottingham, lace-manufacturer, for his various improvements in machines or machinery now in use for the making lace or net commonly known by the name of bobbin-net.—15th March.—6 months. To Rupert Kirk, of Osborne-place, Whitechapel, dyer, for his method of preparing or manufacturing a certain vegetable substance growing in parts abroad beyond the seas and imported to and used in these kingdoms as a dye or red colouring matter for the use of dyers, called SatHower (Carthamus), so as more effectually to preserve its colouring principle from decay or deterioration in its passage from the places of its growth to En- gland, and other parts of Europe.—20th March. —2 months. METEORO- Apno[) ue} Sieh qs ye ures SULT ueyy fpnojp Apno[9 euly quly ‘op Apno[9 “Siu ye urer ‘Apno[y euly ‘ued urea ‘Kpnoyo, Apnopy |q™ [eH | ST- ud Wed BUTT Itt] 90- wey) ApnopD) * Apno[9 auegq| *** ures ym Aui10ig uley| OZ: Aunt07g uley) *** Apnop Wey) *** uy HEY) 96: ould ares Aep Aui103s ‘urezy MOUS! 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SILLIMAN, ne improved riority of its roved Single- by a Jet of tating native ; power of a ncreased_ by the acid, va- ing this ob- ‘lls: being all roughs con- I afterwards Journal, the » that all the ode has since wise, edge to cal, those of al revolution aich support trough must 1, must flow n one of the uch as above subjected to nade of iron, lizement. A rating of the ° to produce cription, and , from Silliman’s with a copy of another, Phil. Mag. Vol.LXW. PL.1N: Z| Between cach pivot & the Galvanic series within. there ts a metallic connexion: hence pieces of sheet copper being placed & ; - a ‘8 , under the pivots. for them tw revolve on. dred soldcred to these pieces of copper causes BE 8 1. | al, a connexion between the poles. of the series in cach trough. | | : N Kon | a Part of the Trough containing the Galvanic series situated as when the acid is off the plates. } N : | io Q LLM AA LL / | Dass y Bis / ¢ | fart of the Trough containing potash when it ts off the Plates. + ; Y, BS | * {| ge | R ) : aan | ipemaee ———! H| wa: Th ee I vy : |\|44e5 Z, ‘ Eg ) Tough is cuactly like the one above t.The' leanne — i fy ‘ ~ ies being LR out t Fhe the Interior. U s SINGLE LEAF ELEC TROME TEIR IMPROVED DEFLAGRATORS BY 1D? HARE. tes rough & Bas lon A bo. 5 we we Fas thase in the roa uc open at bottom containing 100 other respeces. exacté, eg Guikshank plates. in the same space. as ne h of 200 pairs so constructed that by a partial tn the aids may. paciu wn on ool? the plates pe Copper case” : Zine : : es 3 The eases are separated trom. each other. & the Zine from the copper: by pieces oF wood. | —~_ Micrometer wi hich biy a Serewh scale regulates & measures the distance px ay | eLWeN Meine) pen im Wooden stand to which the glass foot ts secured, | | 4 , (ts € | 7 | } ‘ =e f tla: y Saar 3 4 y JS Porter Sc. THE PHILOSOPHICAL MAGAZINE AND JOURNAL. 30° APRIL 1824. XXXIX. Letter from Rosert Hare, M.D. Professor of Che- mistry in the University of Pennsylvania, to B. S1LLimayn, Professor of Chemistry in Yale College, on some improved Forms of the Galvanic Deflagrator ; on the Superiority of its deflagrating Power: Also, an Account of an improved Single- leaf Electrometer; of the Combustion of Iron by a Jet of Sulphur in Vapour; and of an easy Mode of imitating native Chalybeate Waters.* FTER I had discovered that the deflagrating power of a series of galvanic pairs was surprisingly increased by their simultaneous exposure, after due repose, to the acid, va- rious modes suggested themselves of accomplishing this ob- ject. In the apparatus which I sent you, the coils, being all suspended to two beams, could be lowered into troughs con- taining the acid. In another apparatus, of which I afterwards gave you an account, with an engraving for your Journal, the troughs containing the acid were made to rise, so that all the plates might be immersed at once. A better mode has since occurred to me. ‘Two troughs are joined lengthwise, edge to edge, so that when the sides of the one are vertical, those of the other must be horizontal. Hence, by a partial revolution of the two troughs, thus united, upon pivots which support them at the ends, any fluid which may be in one trough must flow into the other, and, reversing the motion, must flow back again. The galvanic series being placed in one of the troughs, the acid in the other, by a movement such as above described the plates may all be instantaneously subjected to the acid, or relieved from it. The pivots are made of iron, coated with brass or copper, as less liable to oxidizement. A metallic communication is made between the coating of the pivots and the galvanic series within. In order to produce a connexion between one recipient of this description, and * From a tract reprinted, with corrections and additions, from Silliman’s Journal, No. 1. vol. vii. and published at Philadelphia; with a copy of which we have been favoured by the author.—Epir. Vol. 63. No. 312. April 1824. Hh another, 242 Prof. Hare on.some improved Forms another, it is only necessary to allow a pivot of each trough to revolve on pieces of sheet copper severally soldered to the different ends of a rod of metal. To connect with the ter- mination of the series, the leaden rods (to which are soldered the vices, or spring forceps, for holding the substances to be exposed to the deflagrating power) one end of each of the lead rods is soldered to a piece of sheet copper. ‘The pieces of copper, thus soldered to the lead rods, are then to be duly placed under the pivots, which are of course to be connected with the terminations of the series. The last-mentioned con- nexion is conveniently made by means of straps of copper, severally soldered to the pivots, and the poles of the series, and screwed together by a hand-vice. Fig.1 (Plate IV.) represents an apparatus, consisting of two troughs, each ten feet long, constructed in the manner which I have described. Each trough is designed to contain 150 galvanic pairs. ‘lhe galvanic series in the upper trough is situated as when not subjected to the acid. In the repre- sentation of the lower trough, the galvanic series is omitted, in order that the interior may be better understood. The series belonging to this trough may be observed below it, in three boxes, each containing 50 pairs, fig. 2. In placing these boxes in the trough, some space is left between them and that side of the trough on which the acid enters, so that instead of flowing over them, it may run down outside, and rise up within them. The pairs of the series consist of copper cases, about seven inches long by three inches wide and half an inch thick; each containing a plate of zinc equidistant from its sides, and prevented from touching it by grooved strips of wood.—Each plate of zinc is soldered to the next case of copper on one side. This may be understood from the diagram, fig. 3. It must be observed, that the copper cases are open only at the bottom and top. They are separated from each other by - very thin veneers of wood. Fig. 4, represents a smaller trough, differing from the others only in length. This I made, with a view to some ex- periments on the comparative power of the galvanic pairs of the form of copper cases, with zinc plates, above described, and those made on Cruickshank’s plan, or of the form used by Sir H. Davy in the porcelain troughs. Fig. 5, represents a box, containing 100 Cruickshank plates (each consisting of a plate of zinc and copper soldered face to face) and slid into grooves, at a quarter of an inch distance from each other; ail the copper surfaces being in one direc- tion, and all the zine surfaces in the other. In this case the zine of the Galvanic Deflagrator, $c. 243 zine plates are exposed only on one side. ‘The sum of the surfaces on which the acid can act is therefore the same as in a deflagrator of 50 pairs, in which each zinc plate is assailable on both sides. It ought to be understood, that the box con- taining the 100 Cruickshank plates is open at bottom, and is of such dimensions as to occupy the place of a box, contain- ing 50 pairs of the deflagrator, receiving the acid in its inter- stices from below, in the same manner, by a partial revolution of the trough, fig. 4. Fig. 6. represents a box, containing 200 Cruickshank plates. This differs from the common Cruickshank trough only in hay- ing the interstices as narrow as those between the copper and zine surfaces of the deflagrator pairs represented by fig.2; and in the mode in which the acid is thrown off or on the whole series, which does not differ materially from that described in the instance of fig. 1. On contrasting the series of 50 (fig. 4) with Cruickshank’s plates in the box (fig. 5) the deflagrating power of the latter was found comparatively feeble; and even when compared with the Cruickshank trough (fig. 6) in igniting metals or car- bon, the 50 pairs (fig. 4) were found greatly superior. The shock from the Cruickshank trough was more severe. You must recollect, that in former experiments I found that galvanic plates, with their edges exposed &s they are in the porcelain troughs used by Sir Humphry Davy, were almost inefficient when used without insulation, as are the pairs of the defla- grator. This demonstrates that an unaccountable difference is producible in the galvanic apparatus by changes of form or position. Being accustomed to associate the idea of the zinc pole, in a Voltaic series, with the end terminated by zinc, and the copper pole, with the end terminated by copper, I was sur- prised to find that, in decomposing water, the oxygen was at- tracted by the wire connected with the copper end of my de- flagrator, while the hydrogen went to the wire connected with the zinc end. Subsequently, however, it occurred to me, that in the deflagrator the zinc pole is terminated by copper, the copper pole by zinc; and hence the apparent anomaly, that oxygen appears to be attracted by copper, and hydrogen to be attracted by zine. The projection from the carbon, exposed between the poles, takes place at the negative pole of the pile, and not at the posi- tive pole, as you have alleged; and thus your observation, that the current of igneous matter is from the copper to the zinc, may be reconciled with the Franklinian theory. The observations which are the subject of this communica- 1 ip) aie] tion, 244 Prof. Hare on a Single-leaf Electrometer, &c. tion, combined with those which you have made of the inca- pacity of the deflagrator, and Voltaic series in the usual form, to act when in combination with each other, must justify us in considering the former as a galvanic instrument having great and peculiar powers. Since the above was written, I have tried my series of 300 pairs. The projectile power and the shock were proportion- ally great, but the deflagrating power was not increased in proportion. The light was so intense that, falling on some adjacent buildings, it had the appearance of sunshine.— Having had another series of 300 pairs made for Dr. Macnevin of New York, on trying it I connected it with mine, both col- laterally and consecutively, so as to make in the one case a series of six hundred, in the other a series half that in num- ber, but equal in extent of surfaces. The shock of the two, consecutively, was apparently doubly as severe as the shock produced by one; but the other phaznomena seemed to me nearly equally brilliant in either way. The white globules which you noticed were formed copi- ously on the ignited plumbago, especially zm vacuo. I have not had leisure to test them, being arduously occupied in my course of lectures, and in some efforts to improve the means of experimental illustration. Account of an Electrometer, with a single Leaf, by which the Electricity excited by the Touch of heterogeneous Metals is rendered obvious after a single Contact. Fig. 7 represents an electrometer, with a single leaf sus- pended from a disk of zinc six inches in diameter, which con- stitutes the top of the instrument. Opposite to this single leaf is a ball supported on a wire, which may be made to approach the leaf; or recede from it, by means of a screw. Above the instrument is seen a disk of copper with a glass handle*. The electricity produced by the contact of copper and zinc, is _ rendered sensible in the following manner. Place the disk of copper on the disk of zinc (which forms the canopy of the electrometer): take the micrometer screw in one hand, touch the copper disk with the other, and then lift this disk from the zinc. As soon as the separation is effected, the gold leaf will strike the ball, usually, if the one be not more than 3, of an inch, apart from the other+. Ten contacts of the same disks, of copper and zinc, will be found necessary to produce a sen- * For the experiment with this electrometer a metallic handle would answer. Its being of giass enabled me to compare the indication thus ob- tained with that obtained by a condenser. + L have seen it strike at nearly double this distance. sible Prof. Hare on the Combustion of Iron, &c. 245 sible divergency in the leaves of the condensing electrometer. That the phznomenon arises from the dissimilarity of the metals, is easily shown by repeating the experiment with a zinc disk in lieu of a disk of copper. ‘The separation of the homogeneous disks will not be found to produce any contact between the leaf and ball. I believe no mode has been here- tofore contrived, by which the electrical excitement resulting from the contact of heterogeneous metals may be detected by an electroscope without the aid of a condenser. It is pro- bable, that the sensibility of this instrument is dependent on that property of electricity which causes any surcharge of it, which may be created in a conducting surface, to seek an exit at the most projecting termination, or point, connected with the surface. This disposition is no doubt rendered greater by the proximity of the ball, which increases the capacity of the gold leaf to receive the surcharge, in the same manner as the uninsulated disk of a condenser influences the electrical capacity of the insulated disk in its neighbourhood. It must not be expected, that the phenomenon above described can be produced in weather unfavourable to electricity. Under favourable circumstances, I have produced it by means of a smaller electrometer, of which the disks are only 24 inches in diameter *. The construction, as respects the leaf, and the ball, re- gulated by the micrometer screw, remaining the same; the cap of a condensing electrometer, and its disks, may be sub- stituted for the zine disk. On the Combustion of Iron by a Jet of Sulphur in Vapour. If a gun barrel be heated red het at the but end, and a piece of sulphur be thrown into it; on closing the mouth with a cork, or blowing into it, a jet of ignited sulphurous vapour will proceed from the touch-hole. Exposed to this, a bunch of iron wire will burn, as if ignited in oxygen gas, and will fall down in the form of fused globules in the state of proto- sulphuret. Hydrate of potash, exposed to the jet, fuses into a sulphuret of a fine red colour. An easy Mode of impregnating Water with Iron. If a few pieces of silver coin be alternated with pieces of sheet iron, on placing the pile in water, it soon acquires a chalybeate taste, and a yellowish hue, and in 24 hours flocks of oxide of iron appear. Hence by replenishing with water * I think I have seen an effect from a disk only an inch in diameter, or from a zine disk having a copper socket to its handle. a vessel 246 Further Remarks on the Theory of parallel Lines. a vessel in which such a pile is placed, after each draught, we may have a competent substitute for a chalybeate spring. Clean copper plates alternating with iron would answer, or a clean copper wire entwined on an iron rod; but as the copper when oxidated yields an oxide, it is safer to employ silver. XL. Further Remarks on the Theory of parallel Lines. [See p. 16].] O apology can be required for resuming the discussion of parallel lines with the view of extending and com pleting the observations already made in the last Number of this Journal. A subject liable to many subtile distinctions must be placed in a variety of aspects, before the reader can form a decided opinion upon it. Besides, the validity of Le- gendre’s demonstrations by algebraic functions has been ‘so keenly contested by men of great eminence, that the full elu- cidation of this point must be not only very curious and in- teresting, but is even of some importance in geometry. i. If we have a number of algebraic equations, viz. Crs ¢ (c » A, B), C= o’(c’, A, B), C"=io(c’, Ay B), &e. in which the letters ¢, ¢’, 9”, &c. are the marks of functions of unknown forms; and if the numbers that vary from one equation to another, be so related that when c= c= c’, we must likewise have C=C’=C”; it will be evident that the functions cannot be of different forms, and that all the equa~ tions will be represented generally by the expression C= ¢(c, A, B). Now if, with Legendre, we apply the foregoing reasoning to triangles, we must conceive a separate figure answering to every equation; the bases being, c, c’, c’; the vertical angles, C, C’, C”; and the other angles common to all the triangles and equal to A, B: then because, by the principle of super- position, we know that, when the bases c¢, c’,c” are equal, the vertical angles C, C’, C’, will likewise be equal; it will follow that, in all the triangles, the vertical angle is the same function of the base and the other two angles; or, that the equation C = ¢(c, A, B) comprehends every case. That we have here faithfully explained Legendre’s process of reasoning is manifest from his own words: Car, si plusieurs angles C pouvaient correspondre aux trois données c, A, B, il y aurait F 4 Ce ee ee ee a Se Further Remarks on the Theory of paraliel Lines. »247 -aurait autant de triangles différents qui auraient un coté égal adjacent a deux angles égaux, ce qui est impossible*. For this means that, if the functions ¢, ¢’, ¢” were of different forms in the several triangles, the vertical angles C, C’, C” would be unequal, when the bases c, c’, c’’ are supposed to be equal, which. is contrary to what is proved by superposition. It is manifest therefore that the reasoning of Legendre ne- cessarily supposes the existence of triangles that have differ- -ent bases, viz. c, c’, c’, and the same angles at their bases, viz. A, B; or, which is the same thing, it supposes that the base of a triangle may vary while the angles at the base remain the same. We may therefore inquire what authority there is for this assumption. If the base of a triangle vary, we may adopt two supposi- tions with respect to the angles at the base: either they may remain the same when the base varies, or they will neces- sarily undergo concomitant changes. Since it is admitted that the vertical angle may vary with the base, there can be -no good reason for exempting the other two angles from the possibility of a like variation. The two cases we have men- tioned are a complete enumeration; and it never can be main- tained that one is true and demonstrated, until the other be excluded. Thus the assumption, on which Legendre’s de- monstrations are founded, is one of two hypotheses that seem equally possible. It is therefore certain, as we have already shown in the last Number, that the functional investigation respecting parallel lines, like the geometrical process of Euclid, rests upon a peculiar postulate, in this respect per- fectly resembling almost every other method that has been proposed for overcoming the same difficulty. 2. Admitting, with Legendre, that the angles A, B, C de- note ratios, or numbers independent on arbitrary measure- ment, it follows, from the principle of homogeneity, that there cannot be an equation between A, B, C and the side ¢ which is measured by an arbitrary unit. ‘Thus the two equations, c=? (A, B, C), C = 9(c, A, B) are equally impossible and absurd: the first, because a mag- nitude that may be converted into a number by any assumed measure, cannot be expressed by three determinate numbers ; and the second, because a determinate ratio cannot involve in its expression, a number that may be varied in an arbitrary manner. But if the equation, C = ¢(c, A, B) * Elem. de Geom. edit. 10me, p. 280. " e 248 Further Remarks on the Theory of parallel Lines. be impossible, is not the whole of Legendre’s process nuga- tory? What are we to think of the attempt to prove that a function, which is a nonentity, must have a determinate form, the same for all triangles ? The truth seems to be, that, in order to render the mode of reasoning imagined by Legendre intelligible, we must strip off the feachional dress in which it is clothed. Since the third angle of a triangle has the same magnitude in all cases when the base and the other two angles have the same values, there must be some general relation between the four magnitudes, or between the vertical angle and some of the three things that are given. But, by the principle of homo- geneity, there cannot be an equation between the base and one or more of the angles: wherefore the equation we are seeking must subsist between the three angles. And since this equation has no dependence upon the sides, it must be the same in all cases; because no reason can be assigned why it should be variable in its form. In this statement of the reasoning, nothing is brought forward except what bears con- clusively upon the point to be proved; and the full force of the evidence is therefore perceived. It certainly amounts to a great degree of probability. It is such a train of thought as, in a process of invention, would lead, with great certainty, to the desired success. But the requisites of a strict demon- stration are in many respects wanting; and, as the whole pro- cedure is a comparison of triangles that have the angles at their bases common, it depends upon the postulate already mentioned. There is one conclusion only that can be reasonably drawn from all that has been said. ‘The same difficulty about pa- rallel lines which has so long baffled the geometer, opposes an equally effectual resistance to the power of the algebraic analysis. ‘The same cause operates in both cases. The de- finition ofa straight line is indirect and imperfect, furnishing no property that will enable us by a direct train of reasoning to investigate the relation between the three angles of a triangle. 3. Legendre estimates all angles by their respective pro- portions to a right angle. But he might, with equal pro- priety, have adopted any other determinate angle as the basis of comparison. Professor Leslie has therefore argued that angles are not to be considered as numbers independent of an arbitrary unit; and that their measures. are just as indeter- minate as the measures of lines. In the last Number of this Journal, we proved the justness of Legendre’s procedure; but it may not be improper to add some further elucidation, and for this purpose we shali choose a particular case. Let \ Further Remarks on the Theory of parallel Lines. 249 Let a,b denote the two remaining sides of the triangle; then the angle C opposite to the base c, must be a determi- nate function of a, 6,c; for the angle has always the same magnitude when the sides have the same values. But, ac- cording to the principle of homogeneity, the expression of C can contain the ratios only of the sides of the triangle; it will therefore be of this form, viz. =A a a C=¢ (< ; =). Again, by trigonometry, we have _ at+b?—c? Cac = a Now the value of C deduced from this equation does not de- pend upon any preconceived mode of measuring. It is not the ratio of the angle to a right angle; it is the length of the arc subtending the angle in a circle of which the radius is unit. In another circle of which the radius is 7, and C the length of the arc subtending the angle, the same equation will become / cos C az?+b?—c? r te 2ab r Chs Sui We can find — in terms of ae and by substituting the Cc value of © , we shall obtain an equation of this form, viz. (Ce a a wa beg =): Again, let Q denote the length of the quadrant, or any other determinate arc, in the same circle: thus Bax Z)=0(% 2): And, since — is the proportion of the angle of the triangle to a right angle, this last equation coincides with that found by ome process. Professor Leslie is therefore not borne out in his philoso- phical argument respecting the similarity of the measures of lines and angles. But it is no more than justice to observe that his reasoning is very naturally suggested by Legendre’s definition. An angle is a magnitude suz generis. It cannot be directly compared with a magnitude of a different kind. If it enter into the same equation with the sides of a triangle, this can be effected in no other way than by the intervention of some Vol. 63. No. 312, April 1824. Ti magnitude 250 Further Remarks on the Theory of parallel Lines. magnitude to which it has a relation. The transcendental quantities = and < find their way into the equation by c : 5 ‘ . means of ==, which is the ratio of two straight lines. All fon COs CEES the quantities ~~, —, S derived from the same angle; and we know that any one of such quantities may be substituted for any other of them, in a proposed function. ‘This proves that Professor Leslie’s reasoning fails; but it does not appear that the fallacy of it could be deduced merely from Legendre’s definition, which determines all angles by their proportions to a right angle. It follows from what we have shown that the angles of the triangle may be considered as ratios, or as numbers indepen- dent of arbitrary measurement, whether they be estimated in parts of a right angle, or of any other determinate angle. But Legendre’s procedure is defective inasmuch as he infers inconclusively from a definition, what can be proved only by the principles we have explained. When the understanding is made fully master of the case by acquiring distinct ideas on the disputed points, it will hardly be allowed that the functional equations are so simple as they appear tobe. To reason about them with intelligence, many notions seem to be necessary that are far removed from the first principles of geometry. They cannot, with much propriety, be considered as propositions merely elementary. We are almost inclined to think that the geometer must have plodded on to the end of his science, before he has acquired knowledge enough to judge critically of the functional demon- strations of the first principles. In this Journal for February, we observe that Mr. Walsh is a strenuous advocate for Professor Leslie’s opinions. His communication is remarkable for being wrong in every point relating to geometry. What can be a greater mistake than to suppose that the angles of a triangle must be evanescent at the same time with the base?. Every one knows that the an- gles may remain the same, while the sides increase to be in- finitely great on one hand, or decrease to zero on the other. But Mr. Walsh makes ample amends by the display of his recondite researches. We are carried back to the principles of philosophical grammar; we are taught to speak accurately are functions of no dimensions in the language of the schools; and the poor geometers, made the sport of every petty whipster, are utterly condemned as ignorant of the philosophy of number. If there be any doubt whether > ie a Further Remarks on the Theory of parallel Lines. 251 whether all this be in its proper place, every one must agree in admiring the writer’s profound learning. 4, Every attempt to overcome the difficulty about parallel lines, uniformly leads to one conclusion; proving that it is insuperable by a direct process of reasoning. New definitions ; new postulates; every mode of investigation that can be devised ; only place the same difficulty in various aspects. ‘The cause lies in the imperfect nature of the definition of a straight line; and, as in other similar cases, we cannot hope for success in this research, except by having recourse to the indirect me- thod of demonstration. In this Journal for March 1822, the foundation of an exact theory of parallels is laid, by proving, in an indirect manner, that the three angles of a triangle are equal to two right an- gles. It is shown, first, that the sum of the angles cannot be greater than two right angles; and, secondly, that it cannot be less. The first proposition is made out by transforming any proposed triangle successively into a series of others, so that the sum of the angles of every triangle shall be the same, while one angle continually diminishes till at length it is less than any given angle however small. ‘Thus the sum of the three angles of the first triangle approaches without limit to the sum of two angles of another; and as the latter sum is always less than two right angles, the former sum cannot exceed the same quantity. We have lately seen a theory of parallel lines by a professor of the mathematics at Basle*, which, like the attempt in this Journal, follows the indirect mode of demonstration; and further resembles it in proving the proposition here: spoken of by the same procedure. But in demonstrating that the angles of a triangle cannot be less than two right angles, the Professor at Basle follows Legendre in the first editions of his geometry, a new postulate being added for the sake of rigorous accuracy. We conceive that this is a blemish in the theory; because, when the indirect method of reasoning is employed, the demonstrations should be effected without any gratuitous assumption. In this respect the advantage is in favour of the proof of the same proposition given in the Num- ber of this Journal already cited, since it proceeds upon the admitted principles of geometry. We shall briefly sketch an outline of the reasoning. Ifa quadrilateral figure be divided into any number of triangles that have their angles upon the sides of the figure, or at points within the figure; then, be- cause all the angles at a point on one side of a straight line, * Nova Theoria de Parallelarum Rectarum Proprietatibus, Auctore Daniele Hubero, Basileense, in Acad. patria Mathem, Professore, et Bibliothecario. Basilez, 1823. 1i2 are 252 Lieut. Zahrtmann on the Mathematical are equal to two right angles, and all the angles round a point, to four right angles; it will follow that the sum of all the angles of the triangles is equal to a certain number of right angles to- gether with the four angles of the quadrilateral. But, as the an- gles of a triangle cannot exceed two right angles, the sum of all the angles of the triangles will be equal to twice as many right angles as there are triangles, wanting the sum of the de- fects of the angles of every triangle from two right angles. Wherefore, by comparing the two equal sums, it will appear that the angles of the quadrilateral are equal to four right an- gles, wanting the sum of the defects of all the included tri- angles. Now suppose a triangle that has the sum of its angles less than two right angles by some given angle; then a qua- drilateral may be constructed that shall have the sum of its angles less than four right angles by any multiple of the same angle; which is absurd, because the multiple may be so taken as to reduce the angles of the quadrilateral to zero, or so as to be less than any proposed angle. We have men- tioned these demonstrations because we have never met with any other indirect proof of the equality of the angles of a tri- angle to two right angles, which is both unexceptionable in point of accuracy, and requires no peculiar postulate. In taking leave of parallel lines, some apology seems to be due to the readers of this Journal for the great length of our observations. But the subject is very curious in itself; it has been keenly debated by very able men; and the contest has been lately resumed in a very high tone, and with additional forces. It therefore seemed very desirable to bring the mat- ter to some decision; and we hope some light has been thrown upon it. On the whole we are inclined to think that much more importance has been attached to the functional investi- gations than they intrinsically deserve. It seems very certain that there was a time when such demonstrations would not have passed current for sterling geometry in the Athens of the North. April 5, 1824, Dis-1oTa. XLI. On the Mathematical and Astronomical Instrument Makers at Paris. By Lieut. ZawRTMann.* EFORE I subject myself to the uncertain event of a sea voyage, I will endeavour to perform the task you have proposed to me, by communicating to you some particulars re- * From M. Schumacher’s Astronomische Nachrichten, No. 42. specting —” < and Astronomical Instrument Makers at Paris. 253 specting the most distinguished artists of Paris. These are, for chronometers the family of Breguet; for mechanical and mathematical instruments MM. Fortin, Gambey, Lenoir, Richer and Jecker; and for optical instruments MM. Lere- bours and Cauchoix. The father of M. Breguet died at the age of nearly 77 years; he was born in Switzerland of French parents, but resided at Paris for the last 60 years of his life, during the whole of which time he applied himself to the making of clocks: but it was only within about 40 years that he constructed chronome- ters. M. Breguet was a member of the mechanical class of the Academy of Sciences, a member of the Legion of Honour, artist to the Board of Longitude, and manufacturer of chro- nometers for the navy. I am unable to speak of M. Breguet without expressing the lively grief which I feel at being obliged to substitute the expression of he was for that of he 7s: my connection with him, while I remained at Paris, had so greatly endeared him to me, that I could not but participate in the sorrow with which all his numerous friends were overwhelmed by his sudden and unexpected death. 1 shall always recall him to my memory as the most amiable of men; and I am persuaded that if (which I do not suppose to be the case) there are any who would dispute with him the honour of hav- ing been the most distinguished of philosophical artists, and of possessing the utmost fertility of genius in his art, yet there are none who would deny that he possessed the best of hearts, and sustuined the noblest of characters. His son, who is a man of 40, directed the business of the house during the life of his father, and will continue the establishment on exactly the same footing as formerly. M. Breguet cultivates the sciences with attention, particularly the physical sciences; and his son, a young man of 18, has already applied himself to the mak- we of chronometers; and, as is stated, with much success. . Breguet has for several years been engaged in concluding a work on clock-making, an undertaking by which he is much occupied and interested. I hope that it will shortly appear, and it is unnecessary for me to state the degree of attention to which it will be entitled. The address of the firm of Breguet is No. 79, Quai de I’ Horloge. After the family of Breguet, those most distinguished for clock-making, and who also are all manufacturers of chronome- ters, are MM. Perlet, Duchemin, M. Berthoud the son, and M. Motel; the first two of these are pupils of M. Breguet, and the others of M. Louis Berthoud; the Navy Board employ M. Motel in repairing and cleaning the chronometers of Berthoud, and are well satisfied with his performance. M. Janvier 254 Lieut. Zahrtmann on the. Mathematical M. Janvier is another who is possessed of considerable know- ledge in clock-making, but has not yet applied it to the manu- facture of chronometers. M. Fortin is 72 years old; he is a provincial by birth, and came when quite young to Paris, where he commenced busi- ness in some of the most humble workshops. He has al- ways worked very assiduously, but has been unable to raise a fortune by his labours. | M. Fortin first attracted notice by the perfection with which he executed balances and pneu- matic machines: he still works, and with much accuracy, notwithstanding his advanced age; and in the construction of measures, barometers, and pneumatic machines, he has scarcely ever been surpassed. ‘The most remarkable instru- ment which has left his workshop is the great meridian cir- cle erected at the observatory, to which it was presented by the Duke d’Angouleme. This instrument is in imitation of the Greenwich circle, but the divisions are executed in a dif- ferent manner, peculiar to M. Fortin; the fastening of the radii at the centre is more firm in his instrument, and the divided limb is formed of an alloy of gold and palladium, a sixth part of which consists of the latter metal ; this combination, without becoming oxidated like silver, and without being too hard for the dividing point, as platinum is, produces a metal upon which the divisions are very easily discerned. M. Fortin possesses a dividing instrument which he has been for 40 years endeavouring to perfect, and of which he makes a profound secret; but notwithstanding all his care, his repeating circles are far from being correct with regard to division. He is a member of the Legion of Honour, and received a gold medal at the exhibition of 1819.—M. Fortin has no son, but will be succeeded by M. Herman, a man of 37 years of age, and a native of Dresden, who has married his youngest daughter. M. Herman has resided 16 years in Paris, where he has been under several masters; and he worked for a considerable time, under M. Fortin’s direction, upon the meridian circle. M. Fortin lives at No. 14, Rue des Amandiers, near St. Géné- vieve. M. Gambey is a native of Champagne, and is 36 years old; he began his career at Paris as a clock-maker, but has since devoted his time to the construction of instruments: he is a man of great merit, and who does not confine himself to imitation; he has made for the observatory a great equatorial, to be moved by a pendulum: the circle is three feet in diame- ter, and is divided upon its edge in equal divisions of 5’; the reading is effected by two microscopes furnished with micro- meters, and placed upon projecting arms from the centre of —— a = a a and Astronomical Instrument Makers at Paris. 255 of the axis. The telescope is by Lerebours; its length is five feet, and the diameter of the aperture is 45 lines. The axis, which is seven feet in length, appears to be less conical than in the instruments of Reichenbach; but it is balanced bya counterpoise, by which it is supported at the end upon two wheels; the instrument is in general perfectly balanced in all its parts: the movement by the pendulum, which is communi- cated by a screw, is sustained uninterruptedly during a period of time rather longer than an hour; the level, or, more pro- perly speaking, levels (for there are two) are constructed in a particular manner, so as to suffer the axis to be levelled independently of its form, being more or less perfectly cylin- drical. This instrument, which was shown at the late exhi- bition of French industry, is without doubt the best of the kind that has ever been executed in France, and the other artists of the exhibition have subscribed to that opinion by attaching to it some lines in honour of M. Gambey. M. Gambey has constructed for the observatory a magne- tic declination circle, and a heliostat. As to his repeating theodolites, of which I have already spoken to you, he has hitherto made three: the first for the Polytechnic School; the second for M. Francceur; and the third for England*. These instruments give great satisfaction, and by M. Francceur in particular I have often heard them praised. The dividing in- strument of M. Gambey’s invention possesses the advantage of not requiring the centering of the instrument that is di- vided,—a process which he has hitherto kept quite secret. M.Gambey obtained a gold medal at the exhibition of 1819. His address is No. 52, Rue Fauxbourg St. Denis. The productions of M. Lenoir the elder are well known, and he now actually works no longer. He is member of the Legion of Honour, and artist tothe Board of Longitude; his son, who is a man of about 40, directs the establishment at pre- sent; he works considerably, but it is rather for engineers and mariners than for astronomers; his nautical instruments ap- pear well made. He'lives at No. 340, Rue St. Honoré. The age of M. Jecker is about 50 years. He is a native of Aix-la-Chapelle, and formerly worked at Ramsden’s. Though the exterior of his instruments is in general imper- fectly finished, and though they possess a certain varnish, yet I do not think that they are bad, at least there are some * [This last instrument was made expressly for Mr. F. Baily, under the direction of M. Arago. The circles are only 10 inches in diameter, and are divided so that 2 seconds are easily distinguishable with a vernier. The execution of the various parts of the instrument does great credit to this celebrated artist. —Ep1r.] among 256 Lieut. Zahrtmann on the Mathematical among them of good quality. M. Jecker manufactures more instruments for the navy than any other artist: but this I sup- pose may be attributed to his moderate prices, for he sells a reflecting circle 10 inches in diameter for 400 francs, while M. Lenoir charges 430, and M. Gambey 500; M. Jecker al- ways makes use of the dividing machine of Ramsden. His residence is at No. 32, Rue de Bondy. M. Richer is dead, and his son does not appear to have any intention of continuing the establishment. He was possessed of considerable merit, and invented a machine for calculating the distances of the moon from the stars; several of the in- struments which M. Freycinet employed in his voyage round the world, and with which he was much pleased, were of his construction. His son, the present M. Richer, lives at the Rue Harlais aux Marais. M. Lerebours is a man of more than 60 years of age, and is esteemed the first optician in France; his workshop has pro- duced several excellent instruments, of which the most im- portant is a telescope, the object-glass of which is nine inches diameter, which he has constructed for the observatory. He sent a quantity of object-glasses of different dimensions to the observatory, in order to be examined, and the greater number of them were found very good; he is a member of the Legion of Honour, and artist to the Board of Longitude. He resides on le Pont Neuf, at the corner of the Quai de Y Horloge. M. Cauchoix, who is nearly 50 years old, is regarded as possessing a more complete knowledge of his art than M. Lere- bours, though he has not brought it so much into exercise : he has constructed a telescope of 11 inches aperture, the largest which has ever been made in France; and likewise a stand of a very ingenious construction to support a telescope. M.Cau- choix lives Quai Voltaire, opposite the Pont Royal. Among the other opticians of Paris, I shall notice only M. Soleil, who has distinguished himself by his activity in the execution of Jentilles d échelon,which are used for light-houses: but though he has received great assistance from the glass- houses, and from M. Fresnel, who furnished him with better tools than those which he possessed, yet they still appear ca- pable of considerable improvement. M. Soleil lives at No. 21, Passage Feydeau, and his manufactory is France Nouvelle, No.21, Rue de Poissonniéres, near the Barriere Poissonniére. As I have never seen a large optical workshop, I am unable to give an opinion respecting them: but M. Thiele, who came to Paris after having worked a year with M. Frauenhofer, was quite astonished at the mechanical poverty which he observed in —* ees and Astronomical Instrument Makers at Paris. 257 in all the optical manufactories of Paris; and remarked to me, that at Benedictbeurn no one would take the trouble to work glass with the hands, in the way in which it was done at Paris. M. Kutsch is one of the best workmen for common mea- suring instruments, He lives at No. 41, Rue des Lombards, Many of these particulars I owe to some interesting .con- versations which I had with M. Arago, and they are but a slight specimen of the kindness which I have received from him during my residence in Paris. But it is not myself only who am indebted to him; and I consider it my duty, before I leave France, to apprize you of your obligations to him for the care and assiduity with which he has compared and ex- amined the instruments intended for you, as well as for the time he has devoted to them at a period when he was more than usually occupied by the exhibition of the products of French industry, of which he is one of the examiners. So that this cannot be attributed solely to the interest which he takes in every thing which relates to the sciences, but also to his desire to serve you, and to evince his friendship for you. : M. Pecqueur, the superintendant at the Conservatoire des arts et metiers, showed me a clock which exhibited with great accuracy sidereal time and mean solar time. He has con- trived this by means of a mechanical invention, which en- ables him to give the same force to two different movements of the clock: for instance, to two wheels, whose movements are to each other in any given ratio. The pendulum of this clock is compensated by mercury contained in the annular space formed by two concentric cylinders, the inner one of which is made of iron, and the outer one of glass: and, as the expansion of iron by heat exceeds that of glass, this serves to augment the compensation already produced by the expan- sion of the mercury. The cylinder of iron is hollow, and open at both ends; and consequently enables the air as much as possible to affect the temperature of the mercury. The rod of the pendulum is mate of steel. M. Pecqueur has not yet fixed the price of this pendulum; at least, I have asked him for it in vain. He has also shown me a similar contri- vance for pocket chronometers. The movements of the watch being attached to this piece of mechanism, the watch will in- fallibly adapt itself to the motion required. This effect is produced by a spring which acts upon the spiral. This invention was presented to the Institute some years since; but no report had been made of it, when a letter of M. Pecqueur induced the President to call for this report in Vol. 63. No. 312. April 1824. K k the 258 On the Instrument Makers of Paris. thie sitting of the 8th of September, in consequence of which the reporter, M. Prony, made his report in the sitting of the 15th of the same month; the other members of the Commis- sion were MM. Arago and Breguet. The invention of M. Pec- queur was much praised, as a thing which had already proved its utility; and the future results of which could not be fore- seen: the Commission therefore proposed that the invention of M. Pecqueur should be received by the Institute to be in- serted in its records; which was adopted after some discus- sion. M. Pecqueur has besides exhibited an ingenious pump which me very little force to carry water to a prodigious height. . Rieussec junior, the king’s watch-maker, No. 13, Rue neuve des petits Champs, has exhibited a chronograph, a sort of counter by the touch, which by pressure given to a spring, makes at the same instant a black mark upon the dial-plate whilst it is in rotation. It is this invention which M. Breguet improved by applying it, but in a different manner, to chrono- meters :—a chronograph costs 400 francs. M. Peschot the elder, No. 18, Rue des filles St. Thomas, has exhibited an extraordinary sort of clock, already rather common at Paris, and which consists only of a needle on a dial-plate of glass; for example, a mirror, without any visible mechanism; this consists in a rotatory weight, contained in a round bex applied to the other end of the needle. In instruments of astronomy and optics the exhibition pre- sents nothing very remarkable, except the instruments of Gambey, of Lerebours, and of Cauchoix. ‘There are some samples of flint glass from the royal glass-works of St. Louis, near Bitsch, Department de la Mozelle. It is said that the Minister of the Interior, M. de Corbiéres, has an intention to render France independent of foreigners for flint glass, by making advantageous propositions to M. Gui- naud, established in Switzerland, and known by his produc- tions in that line, to establish himself in France. There has also been exhibited a light-house with lenses @ échélon on the plan of M. Fresnel and executed by M. Soleil, the mechanism of M. Wagner and the lamp with concentric -wicks of MM. Arago and Fresnel; the detailed description of such a light-house is to be found in M. Fresnel’s memoir on this subject.—It appears beyond doubt that these light- houses with lenses are, as to intensity of light, much superior to those with reflectors: but I believe that the greatest diffi- culty will be to make them quite distinct from each other, especially on a coast where there are many of them. For in making them fixed they lose too much of their advantages, unless Suggestions regarding the Force of Steam. 259 unless they are made cylindrical, which has been projected, but which without doubt must be difficult enough in execu- tion. By making them all rotatory, like that of Corduan, they will be distinguished only by the. difference of the poly- gons of which they consist, producing intervals of light more or less lengthened ; but this difference, if it be not very great, which it can hardly be here, will often be difficult enough to observe by sea, and the difficulty will be the greatest pre- cisely in the circumstances most dangerous for mariners. ZAHRTMANN. XLII. Suggestions regarding some probable Sources of Error in the usual Modes of ascertaining the Force of Steam. Gentlemen, HEN Mr. Philip Taylor published his scale for the force of steam, I was somewhat puzzled to account for its differing, especially at high temperatures, from the results obtained by Dr. Ure; and in seeking an explanation, it oc- curred to me, as it seems to have done to Mr. Herapath, that Dr. Ure’s elasticities were increased by the vapour of mer- cury; but whether the like objection might not apply to Mr. Taylor’s table I could not determine without knowing his mode of experimenting. If, however, the force of mercurial vapour follow a law analogous to that of steam, I should suspect it must be very small at the temperature of 310° or 320° Fahr., since it only amounts to about 30 inches at the high temperature of 680°. The separate force of mercurial vapour might surely be determined by experiment, though, for reasons which will appear by and by, I fear the task would be a difficult one; and, for aught that is known to the con- trary, mercurial vapour, besides exerting its own elasticity, may so act upon or combine with steam as materially to af- fect the result ; or, in other words, the joint effect of steam and mercurial vapour in a mixed state may be different from the sum of their separate elasticities. I would therefore suggest, as a more certain mode of proceeding, that the mercury em- ployed in experimenting on steam be always kept at a com- paratively low temperature. But there seems to be another objection of an opposite kind which attaches to the results of several experimenters, and which does not appear to have been attended to. It is well known that, within certain temperatures at least, the par- ticles of water attract glass and some other substances more strongly than they do each other; and Professor Leslie has shown that, for this reason, air included in a glass vessel can- Kk 2 not 260 - Suggestions regarding the Force of Steam. not be saturated with moisture, because the vapour is con tinually attracted and condensed by the glass*. Now if, as De Luc and many others allege, the quantity of vapour con- tained in a given space be independent of the presence of air, - might we not suspect that the force of aqueous vapour not mixed with air will also be diminished by its contact with _glass, since it is known to be so in the mixed state? But I have no idea of the amount of this diminution, nor how it may vary at different temperatures. However, it is probably so much the greater as the bulk of the vapour in proportion to the containing surface is less; and perhaps every sort of vessel has some effect on the tension or temperature of an in- cluded vapour. May not even the electrical states of the se- veral parts of a complex apparatus have some influence on the elasticity ? In such an apparatus as Dr. Ure employed, this supposed , effect of glass and of mercurial vapour might be in a great measure obviated by making that end of the tube which contains the vapour to consist of metal. This metallic part should be of such a length as to reach below the oil-bath, and then it may join into a glass tube; but such a joint would be a matter of some nicety. The water again ought to be continued down through the metal part and even a little way into the glass, in order that its contact with the mercury may be seen and kept at the same height in the tube. By this means the mercury may be kept away from the heat, and the pressure of the column of water and vapour resting on the mercury will remain nearly the same, except that it may vary a very little as the width of the tube is affected by change of temperature, or by change of strain proceeding from the dif- * The peculiar agitation and fluctuation of temperature, which water exhibits while boiling in glass vessels, are probably referable to the same source, being something like the converse of the above process; the force or temperature requisite to form vapour in contact with glass being greater than what would form it in contact with metal; for vitreous surfaces are known to attract moisture more strongly than metallic surfaces: and so this vapour on leaving the bottom, being of a temperature above 212°, sud- denly expands and mounts up through the water with greater violence than if only of that temperature. Hence when bits of metal are thrown in, the vapour rises from them in preference to the glass; and thus the ebullition is rendered more steady. There may, however, be something electrical in this phenomenon. And it may be remarked, in reference to the foregoing explanation, that the temperature at which vapour is formed under water must always, on account of the hydrostatic pressure, be greater than what would form it at the surface. The particles of mercury again are known to attract each other more strongly than they do glass; but to affirm that this should increase the elasticity of mercurial vapour included in a glass vessel, would be going too far until it were settled by experiment. ferent Mr. Ivory on the new Tables of Refraction. 261 -ferent elasticities of the vapour. ‘The longitudinal expansion of the hot part of the tube or of its contents cannot sensibly affect the results; but as the tube widens, the column of water will shorten, and consequently its hydrostatic pressure on the mercury will be diminished in a very small degree. It is cu- rious to observe what strange mistakes regarding the effects of the expansion of the tube, one of our first-rate authors has fallen into, while playing the critic on Dr. Ure’s experiments. In making experiments on aqueous vapour at a lower tem- perature than that of the apartment, the whole column of water or mercury should be reduced to the temperature of the vapour; otherwise, on account of the facility with which cold descends in fluids, the result might be uncertain. But if the water be frozen, its adherence to the tube will obstruct the free motion of the mercury. It must therefore be very difficult to make accurate experiments on aqueous vapour at or below the freezing point: because the vapour may be partially con- densed if in contact with glass, or the motion of the fluids may be liable to obstruction in the tube. - Besides, in these cases, the mercurial column being about 30 inches long, an error in its temperature may materially affect the observed elasticity, which is then a very small quantity. Yours &c. March 29, 1824. H. XLII. Remarks on an Article published in No. 23 of the Journal of Science, and treating of the New Tables of Re- fraction. By J. Ivory, Esq. M.A. F.R.S. To the Editors of the Philosophical Magazine and Journal. Gentlemen, [* you can possibly find room, I trust you will insert, in your next publication, the following observations occa- sioned by an article on my Table of Refractions that appeared in the last Journal of Science. _In my paper published in the Philosophical Transactions 1823, 1 was particularly guarded to leave nothing uncertain or unexplained respecting the nature of the table constructed to illustrate the theory. Adopting the elementary quantities of the French philosophers, I showed that my table agreed ex-. actly with that in the Connaissance des Tems as far as 81° or 89° from the zenith. I likewise proved that my refractions, to the zenith distance 86°, followed the same law with those of M. Bessel; so that his table and mine are convertible, ‘the one 262 Mr..Ivory’s Remarks on a late Article one into the other, by the addition or subtraction of a con- stant logarithm, or by increasing or diminishing the numbers in a given proportion. The remainder of my table is more uncertain, as I was not in possession of a sufficient number of exact observations for determining the measure of its accu- racy; and of this circumstance I have sufficiently apprised the reader at the end of the table. I should therefore have been highly gratified if any astronomer had undertaken to show its defects by comparing it with good observations at low altitudes. But what has mi in the Journal of Science I can consider in no other light than as a mockery, the more remarkable that, although quite uncalled for, to say no more, it professes to be undertaken in the discharge of an official duty. The article referred to, pretends to compare my table with observations. But it is plainly a comparison of it with the table in the Nautical Almanack; if indeed that can be called comparing two things, which takes one of them as it is, and the other as it is not. Both the tables are computed for the same mean temperature and barometric pressure; and, in ap- plying them to practice, nothing more is necessary than to know the heights of the thermometer and barometer at the several observations. Astronomers are divided in opinion about estimating the temperature. Some reckon by the ther- mometer within the observatory; while others think that the one without is more accurate. ‘There seems to be some ground in experience for this difference of practice; for the errors of some observers are found to be less with the interior, and those of others with the exterior, thermometer. Mr.Groom- bridge has always found an advantage in using the exterior thermometer ; and his judgement in this respect has been con~ firmed by Delambre, who compared the results obtained from both thermometers. ‘There can be no doubt therefore that, with regard to the stars in my paper, p. 490, Phil. Trans. 1823, the exterior thermometer is to be preferred. But in comparing the two tables, the calculations should be made in the same manner from both. It can produce no other effect than to warp the judgement to a wrong decision, if one table be al- tered by empirical corrections made expressly to lessen the errors, while the other table remains unchanged. And if both tables be so altered, the tendency to a false estimate of their comparative merits will only be increased. If there must be a trial, the litigants should come into court upon equal terms. Why should one appear tricked out in all sorts of disguises for the purpose of ensnaring unwary judges into a favourable sentence, while the other stands at the bar with- out respecting the new Tables of Refraction. 263 out any adventitious advantages? I have therefore computed, by the table in the Nautical Almanack, the same refractions which are given in my paper, p. 490, as calculated both by the French table and by my own; and, reckoning the excess of the calculated above the observed quantities for the error, the results of all the three tables, when they are arranged in the order of the stars, will be as below: N.A. F.T. N.T. 1 a“ + 85 45°3 rep + 49 49-9 rao + 78 4462 + 3:8 —10°0 43°7 + 35 + 76 43:3 + 26 +104 47-0 + 12 + 81 42:9 4 2-7 +22°6 +9°7 +142 + 3:9 42:9 sei Bed 4+ 7-9 +6"4 — 23 + 80 +66 —5iGre 417-0 +0°9 + 7:2 — 30 —69 —10°8 +96°7 +549 +4A1*4 —13-0 2 gin —18°6 These calculations are easily verified. The same observa- tions are discussed in a former Number (No. 29) of the Journal of Science. The point aimed is to make the tables approach as near as possible to the observed quantities. This is effected partly by shifting the mean temperature from 50°, which is the standard degree assumed in the construction of the table, to 464°; and partly by altering the allowance made for one degree of the thermometer in the corrections for heat. Thus, excepting what regards the barometer, the table is en- tirely altered as far as the corrections are concerned. — It is therefore highly ridiculous to say that the results in the Jour- nal are calculated by the table in the Nautical Almanack. In the case of Mr. Groombridge’s observations, when the com- putations are fairly made, the errors of the table in N. A. are much greater than those of either of the other two tables. And, I apprehend, it will be found, on examination, that the table in N. A. is less accurate generally at low altitudes than the French table. Besides the observations just mentioned, the results of nine others are given in the Journal of Science; but of these I shall 264 Mr. Ivory’s Remarks on a late Article . shall say nothing, as they are not contained in my paper; and, I have not had time to examine the calculations, There next follows, in the same article, what is called a table of comparative results. Whatever purpose this was intended to serve, it is certain that, as it now stands, it can only mislead. The column, headed 52°, and of course that of differences, should :be both struck out. The mean tem- perature of my table is 50°; and I know no reason why it should be compared with refractions at 52°, rather than any other temperature. The column of M. Bessel’s refractions is liable to be mis- apprehended, from the omission of a very important remark, The numbers in the column, when we refer to the table in F. A., appear to be the refractions at 48$°, 30 B; whereas they should stand at 50°, 30 B, in order to make them com- parable with the other columns. But M. Bessel has very lately discovered that no error existed in Bradley’s thermometer, as he formerly supposed; and that the temperature of the table in F. A., which is marked at 482°, should really be 50°. It is indeed extremely improbable that Bradley, whose mind was, for so long a time, intensely occupied with the deter- mination of minute quantities, should allow any inaccuracy in one of his principal instruments to escape his notice. Very important consequences follow from this change in the temperature of M. Bessel’s mean refractions. | Above 10° of apparent altitude, his table is now very little different from that of the French astronomers; and it approximates in a'still greater degree to my table as far as 88° from the zenith. Thus at the altitude of 45°, the refraction (50°, 30 B) is 58"*36 according to the French table and mine; and, accord- ing to M. Bessel, the same refraction is 58’-27, the difference being no more than 0":09. And this leads me to observe that the writer in the Journal is very careless of accuracy in his strictures. He remarks that, at the altitude of 45°, it appears highly improbable that the refraction at the temperature 50°, or even 48°, can be so much as 5836. Yet this quantity has the authority of the French table, known for so many years, and so much approved of by astronomers. It is the result of almost innumerable observations and experiments by Delambre, Biot, Arago, Dr. Brinkley; and to these we have now to add M. Bessel. The relation of my table to those of best authority ; which I take to be that of the French astronomers, and M. Bessel’s when the temperature, according to his late correction, is taken at 50° instead of 483°; is thus exhibited : ie Alt. respecting the new Tables of Refraction. 265 Alt. net. Bessel. BY ae ° “ ir 4 7] 80 10°30 10°29 10°30 70 21:26 21-23 21-26 60 33°72 33°67 33°72 50 48°99 48°91 _ 48:99 45 58°36 58°27 58°36 40 Y 9°52 1’ 9°40 i’ 9°52 30° 1 40°85 1 40°69 1 40°85 20 2° 39:99 2 38°85 2 39°16 10 5 20°63 5 19°39 5 20°19 9 5 54:3 . 5 52:8 5 53°8 8 6 3574 6 33°6 6 34-7 7 7 259 7 ~ 24-2 7 D254 6 8 31:2 8 28°5 8 29°8 5 9 55°8 9 52°5 9 53:8 4 ll 50°1 ll 46°4 W100 477% 3 14 30°4 14 275 14 26:0 2 18 25°0 18 28°% 18 196 1 24 25:0 | 24 58-2 24 21°8 Q 33. 51° $6 36°1 34 175 All the refractions here set down are reduced to the stand- ard quantities 50°, 30 B. It appears that my refractions are never more than 14” different from those of M. Bessel as far as 88° from the zenith: which is a surprising degree of coin- eidence, when we consider that the first were calculated in the closet, and from a theory depending only upon a few ele- mentary quantities; while the latter were originally deter- mined from Bradley’s observations, and have since been ex- perimentally confirmed and corrected. This is an argument in favour of my theory which I could have learnt only very lately; my paper having been sent to the Royal Society about the middle of June, and the correction of M. Bessel’s table being published in the beginning of September feliowing. To this I hope soon to add another confirmation with respect to the constitution of the atmesphere adopted in my paper; by showing that it agrees with the velocity of sound as de- duced from the satisfactory account of this phaznomenon which we owe to Laplace. In No. 31 of the same Journal, there is an article, p. 139, of some parts of which I have also ground to complain. By turning to p. 141, at the bottom the reader will find that the article contains some insinuations and strictures on my paper by anticipation, befere it was printed and published; but what I judge must injurious is at p. 148. In the Philosophi- cal Transactions, 1823, p. 439, if we put m=2, we shall get, Vol. 63. No. 312. April 1824. Ll a= 266 Mr. W. Sturgeon’s Electro-magnetical Experiments. a=3—A (1 9 Qdx%(1—x) t= M1. ones are 2) 8 fp cost é + (61—4iA) z+ 2iaxz? and in this case we have an exact value of the refraction in finite terms; the formula being integrable. Now the hori- zontal refraction at p. 148 of the Journal is included in the expression we have just found. Again, my general equation m+ between the pressure y and the density z, is y= zm 3 and when m=2, ymzt which is the particular case in the Journal; and when m=4, yrs which is the case I have chosen as best representing the state of the atmosphere. Yet it seems to be insinuated in the Journal that something is found out different from my theory, and about as good. Now this is nothing else than taking away from a person the result of his own labour, and turning it against himself; which is no fair way of dealing. I have now, by such arguments as hastily occurred, endea- voured to vindicate my table from the burlesque comparison in the Journal of Science. Iam far from thinking that the table is the only part of my paper by which science may, in some degree, be benefited. But if it was necessary at this time to discuss the particular results published for illustrating the theory I had to propose, the objections ought, in the dis- charge of a gratuitous office, to have been well-founded; and they ought to have been urged in a candid, open, and manly manner. My purpose being merely to defend myself, I have abstained as much as possible from all remarks on the table in N. A. The construction of that table may hereafter be- come a fair subject of discussion, But it is not impossible that it may be withdrawn, and another of a less mysterious construction substituted in its place; as it appears that a new method for the refractions was read before the Royal Society at their meeting on the 5th February last. : I remain, gentlemen, &c. April 9, 1824. James Ivory. XLIV. Electro- and Thermo-magnetical Experiments. By Mr, Witu1am SturGEon. To the Editors of the Philosophical Magazine and Journal. Gentlemen, LTHOUGH the experiments I have detailed in my for- mer paper have sufficiently satisfied myself with respect to Mr. W. Sturgeon’s Electro-magnetical Experiments. 2677 to the directive exertion of the forces of the differently excited wires or machines, yet it is not impossible that some may still doubt of the sufficiency of those experiments to determine the apparently anomalous phenomena: owing, perhaps they may say, to the difference of the construction of the apparatus employed for exhibiting them. I am persuaded, however, that the following mode of making the experiments will, in all probability, be sufficiently decisive to convince the most sceptical on this point. Suspend the semi-circular copper arc, with its zinc diame- ter, as described in my former paper (the extremities of the metals need not be soldered but twisted together). Wrap one of those joinings of the metals loosely with a piece of tow or unspun cotton. Dip this part of the machine into dilute nitric acid (observe to counterpoise at the other end); present the north pole of a magnet to the same arm, and it will be pro- jected to the right. Take off the cotton, wash and dry the machine, and suspend it as before. Apply the lamp now instead of the acid, and the magnet as in the former experiment; that arm of the ap- paratus will be now propelled to the left. I have merely pointed out this method of making the ex- periments, as the most likély to be understood in comparing the phenomena; but that described with the galvanoscope, for making the chemico experiment, is by far the most efficient and eligible. The results obtained from the mode of comparing chemico and thermo phznomena, could hardly fail to suggest the idea, that chemico-excited wires would have their electrical tension increased by thermo application at the opposite extremity. And in order to try the suggestion by the test of experiment, I had recourse to the above-described simple apparatus. I twisted the copper wire a good length round the extremities of the zinc, so that as great a metallic surface as_possi- ble might be exposed to the action of the acid. After dipping the extremity wrapped with tow into the acid, I suspended the machine in the galvanoscope. On presenting the north pole of the magnet to the arm ascending from the chemico extremity, the latter was deflected to the right about 80°. From that it returned to nearly 20°: thence propelled again to nearly the same distance as before; and so vibrating several times from about 15° to 60°, when I changed the pole of the magnet. It was now deflected in a contrary direction (left) to about 70°: from thence it returned as betore by the silk en- deavouring to untwist itself, and was again propelled by the 12 magnetic 268 Mr. W, Sturgeon’s Electro-magnetical Experiments. . magnetic influence; thus vibrating, still describing a smaller arc, and #pproximating nearer the magnet. When it had become so feeble that the greatest distance did not exceed 30°, IT applied the lamp at the other extre- mity. It was soon propelled to above 400°: and by keeping the extremity of the wires warm (it is well known that zinc would soon melt in a strong flame) I could keep it vibrating at about right angles to the pole of the magnet; for when it went further than 90°, the thermo arm became acted on by ‘the magnetic influence, and conspiring with the reaction of the convoluted silk, the machine was equsriy driven back again 40° or 50°; but by keeping it moderately warm it was kept at between 80° and 90° from the magnet. I now again changed the pole of the magnet,and took away the lamp. The chemico action had now become so feeble as to be just discernible. However, by applying the lamp it soon acquired between 60° and 70°, and could be kept up to nearly the lower point. I have repeated the experiment, with the same success, in about 6} minutes each time. The copper wire was about 1-60th of an inch in diameter; and the zine about twice that thickness. When the lamp is applied before the chemico action gets too weak, this thermo-chemical magnetic experiment, in minia- ture, is most strikingly decisive. Not having it in my power at present to carry on the experiment on a large scale, I am not prepared to say how it might answer. All the pheenomena yet exhibited by the differently excited wires, seeming to be so perfectly analogous in every other re- spect than in the direction of their forces, I have, by parity of reasoning, found no difficulty in producing a thermo rota- tion by the influence of a central magnet. As this experiment seems to have baffled the exertions of some of your scientific correspondents, it may perhaps be considered of some importance in promoting the advancement of the science, I am yours, &c. © Artillery Place, Woolwich, Wm. STurGeon. Feb. 16, 1824. XLV. De- Siena a { 269 ] XLV. Description of a Rotative Thermo-magnetical Experi- ment. By Mr. Wittiam StrurGeon. To the Editors of the Philosophical Magazine and Journal. Gentlemen, AVING promised in a former paper to communicate to your readers the method I have adopted for rotating a thermo-combination by the influence of a central magnet, the following description of the apparatus I have constructed and employ for exhibiting the experiment, with an explana- tion of its management, will, I humbly hope, be sufficiently plain to be understood. NS, in the figure, isthe magnet; Pc P a piece of platinum wire bent into the form of a semicircle or other convenient curve; Ps, Ps are two pieces of silver wire twisted to the ‘former at the extre- mities PP. The other ends of the silver wires are bent downwards at ss; and made _ quite sharp and smooth at the points. These points descend into the metallic cell F E, which contains pure quicksilver, with which the points communicate. A descend- ing point c soldered to the platinum wire, forms the pivot on which the moveable part of the machine turns. A small con- cavity well polished at the bottom is made in the point of the magnet, for the purpose of containing a small globule of mer- cury, and likewise for the rotating pivot to work in. The point c being amalgamated, when it is placed in. this globule of mercury, forms a communication with the magnet ; and the other part of the magnet which passes through the cell communicates with the mercury in that cell: and the points of the silver wires being immersed in this mercury, the metallic circuit is thus rendered complete; first, through the platinum wire from P to ¢; thence through the pivot e the | | s>\ | 270 Mr. Sturgeon on a rotative thermo-magnetical Experiment: the top of the magnet, and along that part of the magnet from the top to the quicksilver in the cell F E: and lastly, along the silver wire from the point s to the extremity at p where it joins the platinum. The other part of the wire machine being on the same principle as that described, the platinum arms of this apparatus, when heated by a spirit lamp or otherwise at the extremities PP, are in every respect assimilated to the arms of the rotating cylinder of Ampere; for the electric fluid is transmitted in the same direction through both arms of the apparatus; and hence the rotating tendency is constant round a central mag- net; and not zmpulsive, as in other rotations with an external magnet. The moveable part of this machine (which is the platinum and silver wires only) will rotate with a facility proportioned to the delicacy of the suspension, the difference of tempera- ture of the parts P and c of each arm, the power of the mag- net, and the dexterity of the experiments. And I must here warn the reader, that this last requisite is not the least to en- sure success in the experiment; for had I not been satisfied that the apparatus was constructed upon principle, I probably might not have persevered sufficiently to attain my object. However, a slight modification of the apparatus considerably facilitates the experiment, and renders it more permanent and beautiful. A circle of lamps are placed on a stage of the same figure, in such a manner that they may coincide with the periphery of the circle described by the points P P of the wire part of the machine, so that the latter may constantly be kept at nearly the same temperature in every part of their revolution. And the shoulder of those arms, or that part of the platinum wire to which the pivot c is soldered, is kept at as low a tem- perature as possible by means of ether or other cooling liquid. If instead of lamps a,circular flame of ignited hydrogen be substituted, and regulated by a stop-cock, this part of the apparatus may perhaps be considered at its acme of per- fection. Another improvement is by having a conducting wire from the pivot c to the metallic cell F E, in the same manner as the conducting wire of the copper part of M. Ampere’s ro- tating cylinders; through the upper part of this conducting wire passes a screw with a milled head, made into the form of acup. The pivot c runs in this cup, at the bottom of which isa small globule of mercury, for the better ensuring the con- tact. The cup is then filled up with ether, and may be sup- plied during the experiment in proportion to the he as e Mr. J. Walsh on Parallel Straight Lines. 271 The lower end of this screw rests in the hole in the top of the magnet; and by turning the milled head to the right or left, the points ss of the silver wires may be heightened or lowered at pleasure; and consequently their contact with the mercury in the cell FE may be regulated to the greatest nicety; the attainment of which was the only embarrassment I had to encounter with the original apparatus. However, by means of this improvement my anticipations were soon agree- ably realized by witnessing the first thermo rotation ever pro- duced by the influence of a central magnet. I must here beg leave to observe, that the only attempt I ever heard of (and the only one perhaps on record) was with the apparatus of Professor Cumming, and a similar attempt by eed Barlow with a combination upon the same _prin- ciples. The latter gentleman, however, has candidly confessed the failure of the experiment, and sufficiently accounted for the in- efficacy of the apparatus upon the principle of its construction. I am, gentlemen, yours respectfully, Artillery Place, Woolwich Wo. STURGEON. P.S.—April 13. I have since succeeded in forming a sphere of galvanized wires, to rotate by the influence of both poles of an internal magnet. This experiment was suggested on reading the late Dr. Halley on the theory of the earth; and although it may not be considered as a proof of that philosopher’s notion of ter- restrial magnetic variation, yet perhaps it may tend in some measure to strengthen the hypothesis. A description of the apparatus shall be the subject of another paper. W.S. XLVI. On Parallel Straight Lines. By Joun Watsu, Esq.* | & this paper my object is not to terminate a controversy, but to render service to science, to banish from it, as far as this is in my power, all fallacious reasoning about an ele- mentary principle which is the basis of all mathematical science. I must observe again, that the difficulty encoun- tered in the theory of Dadra arises out of the nature of things. It arises from this, that space has no limit. Can the geometer imagine space beyond which there is no space? Can * Communicated by the Author. he 272 Mr. J. Walsh on Parallel Straight Lines. he imagine space less than which there is no space? If he cannot, or more properly if there is not, then he cannot ob- viate the difficulty of Euclid’s postulate. I know not how it happens that some illustrious geometers mistake the nature of number, and the manner it presents itself in mathematical investigations. I know not how it is, that the most glaring absurdities are received by geometers, even as necessary truths; and that too in a science conversant only about TRUTH. It is acknowledged to be a fact antecedent to all hypotheses, that the arc and tangent of a curve may become nearer to each other than any given difference; that is to say, there is a given: difference that is less than itself. It is said to be a fact, in the theory of maxima and minima, that space can exist and cannot exist at the same time. And these two proposi- tions are the basis of the modern mathematics. Does this arise from the nature of elementary education; from spending the important period of youth almost exclusively in the study of the languages of Greece and Rome? ‘This is a circumstanee, I suppose, which the well-being and advancement of society render absolutely necessary. But are the powers of reasoning by this means deranged, from having no fixed principles al- ways to refer to? On the subject of this paper, I find the following observations in page 296, fourth edition of Leslie’s Geometry. It appears they were advanced by M. Legendre in reply to. the objections ot Professor Leslie to his theory of parallels. La loi de ’homogenéité est une loi générale qui n'est jamais en défaut. Every body is sensible of this, In the next sentence he says: L/angle est une quantité que je mésure tou- jours par son rapport avec l’angle droit. Again he says: Eangle droit est Vunité naturelle des angles. 'Yhat is to say, particular sounds of the human voice and linear space are homogeneous magnitudes. Locke falls into the same absurdity, when he says, ‘ Number measures all measurables.” Geo- meters are led away by the erroneous manner in which num- ber presents itself in language. I define numbers to be arti- culate sounds used as the signs of our ideas of certain relations between homogeneous things. We measure magnitude by magnitude homogeneous to it; and number is the verbal ex- pression of the relation found to exist by actual measurement. And figures are the written characters which as it were re- present numbers, and excite in us the ideas of certain rela- tions. The term number is generally transferred from the verbal expression to'the written character. It is not until the binomial calculus shall become a general object of study among mathematicians, that reason, so long and so much distorted Mr. Walsh on Parallel Straight Lines. 273 distorted by the false language of the infinitesimal calculi, will have assumed its proper empire in mathematical and phy- sical investigations. 3 I cannot discover in the second note, tenth edition, of his Geometry, where he applies functional equations tothe theory of parallel lines, that M. Legendre assumes, that if at the ends of any straight lines ¢, c” &c. angles be formed equal each to each to the angles at the base c of any given plane triangle, triangles will be formed on each of those lines. In fact, his reasoning is similar to the following: ‘“ Having measured two angles of any plane triangle, it is required from these to determine the third. ty * The vertical angle C is determined by the angles A, B, and the base c. For when A=0, B=0, c=0, then will C=0. But C, a number, being heterogeneous to the line c, then any particular magnitude of C cannot depend on any particular magnitude of c, then the magnitude of C can only depend on the magnitudes of A, B, and be derived from them. ‘Therefore when any two plauve triangles have two an- gies of the one equal each to each to two angles of the other, the third angle of the one will be equal to the third angle of the other. It follows from this, that the sum of the three angles of any plane triangle is equal to two right angles. ** ‘The base and its adjacent angles being given, to construct the triangle ? ** With the base make an angle equal to the given acute angle; then at any point in the base, or the second line, ac- cording as the other given angle is acute or obtuse, make an angle equal to the other acute angle; then a triangle will be formed, having its angles equal each to each to the angles of ihe triangle to be constructed. Then at the other end of the base make an angle equal to the other given angle, and the thing required is done. Yor if the lines forming the angles at the base, do not meet when produced, then the vertical angle will vary for particular values of the base, which is shown to be impossible.” Now I shall object to the preceding reasoning, that the arc C and the base c may both be compared to the straight line radius, and may be expressed by equations of equal dimen- sions, as I have demonstrated in my [Essay on the Binomial Calculus. The reasoning of M. Legendre therefore fails al- together, as must all attempts at obviating the difficulty of the axiom of the illustrious Greek geometer. Cork, April 15, 1824. Joun Watsu. Vol. 63. No. 312, April 1824. Mm XLVII. 200- Ea: 24s ol XLVII. Zoological Notices. By Mr. Joun Epwarp Gray. On the Characters of Roophytes. GINCE the discovery by Ellis, that the corals and other zoophytes were the houses of animals, there appears to have existed in the greater nuinber of persons a considerable difficulty to draw the line of demarcation between them and the Marine Algz; but this difficulty must have arisen from the consideration of them as animals themselves, and not as the houses of animals, in the same manner as shells are to the Mollusca. For in the consideration of them in the latter point of view, it is impossible that they can contain the ani- mals without a space to hold them; this space, or at least its mouth, as the animals are always regularly radiated, is con- stantly regular and mostly symmetrical ; so that let the structure be either a simple tube, or many tubes close together or sepa- rated by the intervention of cretaceous matter forming a plant- like structure, they always terminate in a regular mouth. Whereas marineplants are formed entirely of cellular structure, which is condensed on the surface to the form of a cuticle (which is sometimes, as in the Sponges, mucilaginous), and they very seldom have any apertures on their surface, or, if they have, these are always irregular. Now since Silex is generally allowed to be found on the sur- face of many Monocotyledones, and Tabashecr in the joints of the Bamboo, why should not chalky matter be found in Alge? Indeed itis to be seen on the surface and internal structure of several Zhalassiophytes which have never been con- sidered as Zoophytes. Therefore I should consider none of the marine plant-like bodies to be of animal formation, unless cells could bediscovered opening on their surface with regular apertures; and consequent- ly there isnoreason why the genera Corallina, Dichotomaria, Pe- nicillus, and Flabellaria, of Lamarck, and perhaps even Nulii- pora of Cuvier, should not be placed with the Alga. The first of these I have ventured to remove to their ancient habi- tation, on account of their bearing tubercles very similar in appearance to those of many of Ceramiade or marine conferve ; and the first section of £labellaria, especially Flabellaria pavoniaof Lamarck, bears a very great affinity to, as the above- named author justly observes, if it does not actually belong to the same genus as the Ulva pavonia of Linnzus, which Draparnaud the elder has formed into a genus under the name of Zonaria. This affinity induced me to place the Coralline so close to the Sonaria, in my father’s Natural Arrangement of British Plants. eee a ee © “I Or On Gadinia, a new Genus of Patelloid Shells. GADINIA. Testa univalvis, non symmetrica, oblique conica; vertice ob- tuso, subpostico. Apertura suborbiculata, irregularis ; cavi- tas simplex, sulco in latere dextro prope limbum anticum, impressionis muscularis ; zmpressio muscularis elongata, ar- cuata, submarginalis. Animal ignotum. This genus is instantly to be distinguished by the peculiar toate which is formed, there is little doubt, by the tube that directs the air to the respiratory cavity of the animal, with which unfortunately we are unacquainted. I have only observed one species, which, having been called Le Gadin by Adanson, I have consequently named 1. Gadinia afra. Testa oblique conica, alba, radiatim striato- costata subsquamosa ; vertice subleevi; marginibus crenu- latis. Patella afra. Gmelin 3715! Dillwyn. Rec. Shells, i. 1046 ! Patellan. 1. Schroeter. Eznl. ii. 441. Le Gadin. Adanson Senegal. 33. t. 2. f. 4! _ Icon. Gaulter t. 9. f. 6. Martini i. 93 t. 5. fi $4. Inhabits Coast of Africa. Coast of Cape Manuel and the Island of Goree. Adanson. Shell white univalve not symmetrical, obliquely conical with an obtuse vertex placed towards the hinder part, rayed with many rather scaly rib-strie diverging from the apex; the aperture is nearly orbicular, crenulated, sometimes slightly extended, on the right anterior lateral portion, just over the groove; the cavity is simple, concave with a slight proare near the front part of the right limb of the horse-shoe shaped, sub-marginal muscular impression. Length and breadth about $ inch. This shell is not uncommon in collections, and may be con- founded with Szphonaria; but in that genus the groove is placed in the muscular impression, and divides it into two por- tions. I had, in a paper which it was my intention to have published the beginning of last year, called the latter genus Liria, believing the Patella tristensis of Dr. Leach to be Le Liri of Adanson and consequently the Patella perversa of Gmelin; but as Mr. G. Sowerby has lately published this shell with two or three others under the generic name of Szphonaria, it should be adopted. He has however in my opinion fallen into the common error M m 2 of 276 On some new Species of Ampullariade. of modern conchologists, of making too many species; for I have good reason to believe that all the specimens that he has figured, except S. tristensis, (with several varieties in the Bri- tish Museum), belong to one species, for which I propose the name of S. radiata. ‘There is, I believe, another species found in the United States, which Mr. Say has described under the name of Patella alternata, which, should my surmises be cor- rect, will be a curious circumstance, as the other two species are confined to the African seas. On some new Species of Ampullariade. Marisa intermedia. M. testa subdiscoidea, levi, pallide olivacea, lata fusco-uni- fasciata; spira concaviusculo-plana, apice subprominente acuto; columella (axi) concavo-conica effusa. Inhabits Brazils. Mus. J. Sowerby, Nostr. Shell nearly discoidal, smooth pale green with a broad brown central spiral band, spire very slightly concave, nearly flat, apex slightly prominent acute, columella (axis) conical concave effused exhibiting most.of the whorls; aperture nar- row, half as broad again as the last whorl but one, peristome simple slightly reflexed in front, axis 31, diameter 1 inch. Marisa is the name which I propose for a genus of shells which has been confused with Ampullaria, but which differs from it in having a horny operculum and simple peristome. This shell is very interesting as being intermediate between Ampullaria Cornu arietis and A. effiusa of Lamarck ; and I be- lieve that Mr. Swainson had confounded it with the former species when he observed that Mr. G. B. Sowerby had dis- covered the operculum of that species, for I have reason to think that my specimen is the fellow to the one in Mr. Sowerby’s collection, as he presented me with it at the time he bought them; so that the operculum of that species is still a desidera- tum, although I have no doubt that it is furnished with one. This shell is instantly to be distinguished from the two former species by the flatness of the spire, and the size of its umbilicus ; and the two specimens that I have seen have only one broad band, whereas the other species have five or six narrow ones, but this may be subject to variations. The controversy that has arisen regarding the situation of the M. Cornu arietis is an illustration of one of the numerous errors between analogy and affinity ; for there is no more rea- son for placing it amongst the Planorbes on account of its sub- discoidal form, than there would be for arranging the Bats with the Birds on account of their fluttering through the air. As to the aes ws 1b ot ee * aang a Ci ie eae a On some new Species of Ampullariade. 277 the assumed absence of the columella, it is no more wanting in this than in any other species of the genus. In fact, it only-differs from them in the size of the space be- tween the whorls; and if it is to be placed in the latter genus on that account; several other shells, such as the Stazrcase Tro- chus, &c. must be also added to it. Iam the more astonished at the controversy, as one of the parties has travelled through the Brazils, where this genus is found, and where he might have learnt that the Marzs@ have gills and breathe air througli the medium of water; and every English conchologist knows that the Planorbes on the other hand breathe, by means of a closed bag, free air, which they come to the surface to procure. Consequently these two genera cannot have any affinity with each other, and their resemblance must be purely analogical, and few persons would be inclined to place genera with such different animals side by side. Again, I do not know any of the Planorbes to be banded, as is the case with most of the Ampullariade, and colour is not an unimportant adjunct to the natural arrangement of organized bodies, as most zoologists and botanists are well aware. Bithinia lutea. B. testa ovata, levi, pallide lutea, pellucida; anfractibus qua- tuor, convexis; apice obtusa; columella perforata. Ditches, East Indies. Mrs. F. Gray. Shell ovate, smooth, pale yellow, pellucid ; the whorls four, rather convex, the sutures distinct; the apex obtuse as if the first whorl was broken off; the axis with a narrow deep per- foration, axis =5,, diameter 24, of an inch. Bithinia is a generic name proposed by Mr. Prideaux for the small ovate species of Ampullariade which have a shelly operculum and slightly thickened peristome, of which Helix tentaculata may be considered the type. Bithinia pusilla. B. testa ovata, levi, alba, hyalina, anfractibus quatuor, con- vexis ; apice subobtusis ; columella imperforata. Ditches, East Indies. Mrs. F. Gray. Shell ovate, smooth, white, hyaline, with four convex whorls divided by very distinct sutures, and rather obtuse at the apex; the axis is imperforated, axis 3,, diameter 3%, of an inch. I have transmitted both these latter species to the Baron Ferussac, who declares them to be as yet undescribed and new to him. XLVIIL. Ana- [ 278 J XLVIII. Analysis of Professor Hausmann’s Essay* on the Geology of the Apennines +. HE first section contains an account of the general ap- pearance of the Apennines. The most elevated point of the range is 8934 feet above the level of the sea. The second section, entitled -Apenninorum constructio interna, embraces the geological description. From this it appears that the struc- ture of this mountain chain is peculiarly simple, containing no rock of any consequence, except a white limestone of uniform aspect, rarely containing foreign substances or petrifactions. In the immediate neighbourhood of the Alps, however, and in the southern part of the chain in Calabria, there are rocks of older formation. In the lateral chains there is considerable variety, and transverse sections of these mountains often pre- sent alternations of various rocks. The Apennines differ from many other mountains in this, that in many places where strata of different formations are observed, the more ancient are found neither in the centre of the transverse chains, nor in the more elevated parts, but on the sides and at inferior elevations. : From analogy we should expect primitive rocks in these mountains; but from the observations of Professor Hausmann they appear to be wanting, except towards Calabria. The observations of Viviani, Spadoni, Santi, and others, are no- ticed; but they do not appear to be confirmed by those of our author, who however offers no decided opinion of his own, in regard to the formations of Giglio, Elba, &c., which these writers have considered granite and gneiss. The transition formations are the most extensive and im- portant; comprising the Apennines of Genoa, Lucca, Mo- dina, a part of Tuscany, and various other places, always re- posing on primitive rocks. The rock named maczgno and pietra serena, which is extensively used in Florence for archi- tectural and ornamental purposes, appears to be a variety of grey wacke, and occurs in all parts of Italy where the transi- tion rocks are found. The grey wacke in different parts of Italy, observes Prof. H., is not so varied in its grain, and in other respects is more simple than that of Germany. Quartz is the predominating ingredient, together with particles of * De Apenninorum constitutione geognostica commentatio, in consessut Soc. Reg. Scient. D. XVI. Novembr. An. MDCCCXII. ad anniversarium solemne celebrandum habito, recitata a 10. Frid. Lud. Hausmann. Got- tinge MDCCCXXIII. + From the Boston Journal of Philosophy and the Arts, Nov. 1823. black Professor Hausmann on the Geology of the Apennines. 279 black siliceous slate, and scales of silvery mica.. The cement is present in small quantity, and is even sometimes wholly wanting, in which case the portions of quartz lose the granu- lar form, and constitute a continuous mass, making a transition from grey wacke to quartz rock. At other times it passes into clay-slate and into compact limestone. Clay-slate, flinty-slate and tale-slate are next noticed; the latter occurring more frequently and in larger masses, passing on the one hand into clay-slate, and on the other into chlorite- slate. When mixed with quartz it forms the “ saxum forna- cum,” or Gesfellstein (a kind of ovyen-stone). This rock was noticed by Saussure* and St. Fond +, between Genoa and F'i- nale, alternating with compact limestone and clay-slate, and is hence inferred to be of secondary formation, as is likewise the gneiss observed by Saussure ¢ near Veltri. Compact limestone, which is so important in the geological structure of the Alps, is not less so in that of the Apennines. It alternates with grey wacke and clay-slate; in some places passing into those rocks. Its colours are various, but grey is the most common. It contains but few organic remains; a rare specimen of an ammonite was met with by Micheli§, which is preserved in the collection of Professor Targioni at Florence. When the compact limestone is mixed with quartz and mica, it constitutes the pietra forte, much used at. Florence and other places for paving the streets. The transition rock of most interest in these mountains is the brecciated limestone. Some important observations upon this rock have been made by Brochant||. It is apparently composed of fragments of limestone, of various shapes and co- Jours, united by a calcareous cement, sometimes mixed with talc, clay-slate, and other matters. Its colours are strongly contrasted, and it has sometimes the character of the beautiful African breccia. In other instances it approaches the antique Cipolline marble. Where the nature of the fragments does not differ greatly from the cement, there takes place a transi-- tion into compact limestone, or marble, which was noticed near Carrara, where the brecciated marble alternates with the compact. Professor Hausmann describes the appearance of the brec- ciated limestone of the Apennines, as rough, and traversed by numerous fissures, which are particularly conspicuous where the cement is softer than the included fragments, and being * Voy. dans Jes Alps. vol. iii. p. 167. + Annal. du Mus. vol. xi. p, 222. { Voy. dans les Alps. vol. iii. p. 159. § Ferber’s Briefe, p. 327. || Jour. des Mines. N. 157. p. 321. acted 280 Professor Hausmann on the Geology of the Apennines. acted upon by air and moisture, is broken down and washed away. This most beautiful breccia is known by the name of marble of Seravezza, and is much used for ornamental pur- poses. Our author supposes it to be the variegated stone referred to by Strabo*. The celebrated marble of Carrara is considered by Prof. H. as belonging to the transition formation, contrary to the opinion hitherto maintained by geologists. It is connected with and passes into the brecciated limestone and grey wacke, and these rocks alternate more or less with each other. This marble forms high mountains, with steep acclivities, and narrow valleys: the rocks are destitute of vegetation, and distinguished at a great distance by their snowy whiteness. The colour of the Carrara marble is injured by exposure, acquiring a brownish tinge probably from a small quantity of iron which it contains. Iron pyrites are found in it, together with calcareous spar and rock crystals. Professor Hausmann observes, that when the Carrara marble is cut into long and thin pieces it is flexible like some varieties in North America. The next rock described is the Gabbro of Von Bucht+; this is one of the most beautiful and remarkable rocks of the secondary formation. _ Prof. H. observes, that, although from his examination of this rock in the Apennines, he is satisfied that it is not a primitive rock; yet he would not maintain that Gabbro is in every case a member of the transi- tion formation. Under the term Gabbro he includes serpen- tine, the Gabbro of the Italians, anda rock called in Flo- rence granitone, composed of saussurite and diallage (Eupho- tide of Hatiy). ‘These rocks are shown to be but varieties of the same, often containmg asbestos, in which case the hard- ness of the compound is diminished, and the quantity of magnesia in it is increased. Four varieties of Gabbro are de- scribed, viz. i. Granular crystalline Gabbro, containing quartz, horn- blende, prehnite, and a substance which has not been ex- amined. This variety passes into jasper. 2. Porphyritic Gabbro, including the Nero di Prato. The principal part of this variety is serpentine, in which particles of schillerstein are seen. 3. Spotted Gabbro, principally serpentine with compact globules of saussurite. 4. Common Gabbro, or serpentine. * Geog. lib. v. : + Ueber den Gabbro, von Leopold Von Buch, Magazin der Gesellsch. naturf, 1810, IL p, 128. These —— Professor Hausmann on the Geology of the Apennines. 281 These observations do not exhibit any uniform regularity in the relative situation of the transition rocks of the Apen- nines; but they are most probably to be referred to one epoch. The direction and inclination of the strata are very various. Prof. H. thinks it not improbable that these rocks are a con- tinuation of the secondary formations of the Alps. After remarking that the upper Apennines exhibit a more varied structure than the other parts, Prof. Hausmann pro- ceeds to describe the rocks between Tuscany and southern Calabria. The compact limestone already noticed, consti- tutes the most prominent geological feature, and is stated to resemble the white Jura limestone, It does not contain beds of oolite, which are often met with in the latter, but calcareous and argillaceous marl and hornstone. Professor Hausmann observes that it is difficult to decide whether the limestone of the Appennines is to be referred to the newest secondary formations, to which the Jura limestone belongs, as there are no super-incumbent formations, nor petrifactions sufficient to determine the question. The transitions and al- ternations of the strata increase the difficulty. From various considerations, however, he is inclined to refer the principal part of this limestone to the same formation as the Jura limestone. If this opinion is correct, the lower part of the plain of the Po with the Adriatic sea, is to be considered as a longitudinal valley extending from N.W. to S.E. in this limestone formation. The principal boundaries of the for- mations have the same direction, with some little interruption. The continuation of the line of the white limestone of the Apennines above Bologna, towards the N.W., is found near Arona, in the same limestone. The line of the transition mountains, which begins in Calabria, skirts cape Circeo, and with increasing breadth stretches through the southern part of Tuscany to the upper Apennines, and thence to the Alps. The primitive rocks begin in the southern extremity of Calabria, and in Sicily, touching either the granite of Giglia and Elba, or, if this rock belongs to the transition formation, probably the primitive rocks of cape Corso in Corsica. The tertiary mountains are next described, and, for the most part, are so completely separated from the Apennine limestone, that no transition can be discovered. ‘There are, however, some exceptions in the territory of Otranto, where a transition was first noticed by Brocchi. The tertiary formations are distinguished by Professor Hausmann into more general and more local. The more general consist of argillaceous marl, passing on one side into slate-clay, and on the other into sandstone; Vol. 63. No. 312. April 1824. Nn plastic 282 Professor Hausmann on the Geology of the Apennines. plastic and slaty clay; sandstone; conglomerate; and sand. The latter is always the newest. In these formations fossil organic remains occur, with bones of colossal animals, and shells. Bitumen, sulphur, pyrites, barytes, and strontian are also met with. The sulphur is often beautifully cry- stallized. The more local tertiary formation consists of gypsum, cal- careous tuffa, and volcanic tuffa. The alabaster which is wrought at Florence into various ornamental articles, be- longs to the gypsum of this formation. The greater part of the Apennines being composed of limestone, it is easy to ex- plain the production of the calcareous tuffa, at their base and in the valleys. The celebrated Travertina marble is a tuffa of this kind. The quantity of calcareous tuffa in Italy, and its varied appearance, are wonderfully great. Prof. H. points out some of the most remarkable localities. He remarks that different local formations of this substance can be distinguished ; some having been formed at the bottom of the sea, as is proved by the marie remains found in them; while others have re- sulted from the sediment of fresh-water rivers and lakes. The fresh-water strata exhibit also proofs of difference in age. Those which alternate with the volcanic tuffa, as seen in some of the hills of Rome, the Aventine for example, and in the vicinity of the city, are most ancient. ‘Those strata which cover the volcanic tuffa, and the tuffa upon which Tivoli is built, are of more recent origin. The newest formation is that daily forming, as at the baths of St. Philip, &c. The volcanic tuffa, although composed of volcanic matter, in the state in which it is now observed is to be referred to the aqueous depositions, as has been proved by Von Buch in his excellent remarks upon the country about Rome*. It appears to be confined to the south-western side of the Apennines, and is separated into two portions, one of which extends from the neighbourhood of Rome to the Pontine marshes and vicinity of Bolsenna. The other portion, which is less extensive, occurs about Naples. In the first, leucites occur, but are altogether wanting in the second, into the com- position of which felspar enters. The volcanic tuffa is of later formation than the marls, sandstones, and sand before noticed; as is well seen in the ps onrieaa of the Vatican, where the sand is full of marine shells and rises from under the tuffa. This fact was first de- scribed by Von Buch. Professor Hausmann concludes his memoir by remarking, Ist, that there are no true volcanic rocks, nor rocks of the * Geognost. Beob. II. p. 60, 202. trapp Chemical Examination of American Green Feldspar. 283 trapp formation (Trappgebirgsarten) in the central chain of the Apennines, although Ferber* and some other writers have advanced an opposite opinion. 2d, That the true volcanic formations are found only on the south-eastern side of Italy, with the exception of the extinct volcanic mountain Vulture. The greatest extent of the volcanic rocks is in the line of those of more remote origin, and but a part of them, as Vesuvius, the extinct volcanoes of Nemi and Albano, and the formation near Borghetto, approach the Apennine limestone. XLIX. Chemical Examination of Green Feldspar from Be- verly, Massachusetts. By J. W. WexstEr, M.D.+ yeas mineral is peculiarly interesting, as another instance of the great similarity existing between the minerals of this country and those of the north of Europe. The only specimen which I have seen from this locality is connected with quartz and mica, constitutng a perfectly characterized gra- nite. The colour of the feldspar is of a lively verdigris green, the fracture is foliated with a high degree of lustre, and the concretions, or imperfect crystals, are from a quarter to half an inch in diameter. The intermixture of the quartz, which is white, with the brown mica and the green feldspar pro- duces a beautiful effect. My first object in submitting the green feldspar to a che- mical examination was to ascertain the proportion of alkali it might contain. For this purpose, one hundred grains reduced to an impalpable powder were mixed with twice their weight of boracic acid, as proposed by Sir H. Davy. The mixture, after fusion in a platina crucible, was digested in dilute nitric acid. After separating the siliceous earth, the bulk of the so- lution was reduced by evaporation, supersaturated with car- bonate of ammonia, and boiled; after filtration, nitric acid was added to the liquor, which was again filtered, and exposed ~ to a temperature sufficient to decompose the nitrate of am- monia that had been formed. ‘The salt obtained was nitrate of potash, and weighed 23°6 grains, equivalent to 11:1 of alkali, Another portion of the specimen was treated in the usual manner. ‘The details of the processes it is unnecessary to re- eat, as they presented nothing peculiar. The composition of this feldspar was found to be as follows : * Briefe aiis Wiilschland, p. 430. + From the Boston Journal of Philosophy and the Arts, Nov. 1823. Nn2 Silex 284 Notices respecting New Books. 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Sie MAY 1824. LIII. Descriptions of several new Species of Ascidia. By C. A. LesuEvur.* Genus ASCIDIA, Lin. 1. ASCIDIA atra. Body subcylindric, elongated, arquated, sessile; the superior part more slender, terminated by two unequal tubes, slightly separate and parallel; these tubes have each a terminal opening, which in the shorter tube is closed by five, and in the longer one by six, triangular valves; the substance of the exterior sac is very firm, almost smooth, opaque, and very deep violaceous or blackish.—It occurs attached to rocks, amongst Opuntia, many species of Sertularie, and broken shells. Its position is inclined, being adherent by the side of the base, which is a little more in- flated than the other parts of the body.— We observed this species at the isles of St. Vincent and Guadaloupe, where, however, it is rather rare. Whilst dredging in the bay of Calicoua, we drew this species from the bottom of the water, with many other objects, amongst which was a beautiful Ho- lothuria, marbled with brown, red, white and blackish, which had the property of dissolving so rapidly as to be observed with difficulty. 2. A..cavernosa. Body oblong, irregular, terminated by two unegual tubes; that of the branchia and mouth much longer than the other, and directed upwards; that of the ovi- duct and excretions situated at the base of the first and la- teral; their apertures are entire, without marginal elevation, or apparent hair, and of a deep colour within; the exterior en- velope is coriaceous, thick, very firm, opaque, rugous and folded, particularly towards the base, where the folds, united in fasciculi, form three points of attachment, by means of which the animal secures itself firmly to the interior of cavities in rocks and old madrepores; the colour is that of burnt terra- * From the Journal of the Academy of Natural Sciences of Philadelphia, vol. iti. No. 1. for April 1823. Vol. 63. No. 313. May 1824. Ss sienna. 322 Mr. C. A. Lesueur’s Descriptions sienna.—This species is found only within the cavities of rocks, which are generally covered with «lve and other marine plants, at the island of St. Bartholomew. Length 2 inches 5 lines, breadth 1 inch and a half. 3. A. albeola. Body subpyriform, more inflated above, terminating in two apertures, that of the branchia rather more elevated; base destitute of a peduncle, but spreading a little ‘outwards to increase the surface of attachment; colour white, diaphanous, exhibiting an interior globular, red, point. This species being small, measuring but a single line in height, presented less obvious characters than the preceding species; it is gregarious, attached to the surface of rocks, upright, and presents a peculiar aspect, which at once distinguishes it from any of the other species described in this paper; it may possibly be the young of a larger species.—Inhabits Guada- loupe. { 4. A. multiformis. Body variable in form, sometimes de- ressed or orbicular; sometimes elongated and projecting two fe unequal tubes, which, as in the other species, are di- 5 . . stant when collapsed, and divergent when projected; the open- ing of one of these is furnished with four, and of the other with five, triangular lips; dase sessile, discoidal, forming an attaching surface wider than the body; substance soft, dia- phanous and tinted with red; length about 5 lines, breadth 2 lines. —Many specimens are much smaller than the size here indicated; but whether or not these are young, or varieties, can only be determined by a series of regular and constant observations. Like the preceding they are gregarious, at- taching themselves to rocks on the shore of the island of Gua- daloupe. Var. a. Differs in being much larger, more solid and more opaque; the apertures are entire; the interior of the opening is black, and the general exterior colour, gray; the almost smooth surface is interrupted by a few wrinkles; it was found covered with ulve, and resembled a beautiful green Lycopo- dium; the foot was less dilated than that of the species; the apertures are terminal, conic, divergent, sometimes rectilinear and sometimes recurved.—It is a native of the coast of Gua~ daloupe. . 5. A. variabilis. Body variable in form, oblong, sessile ; base inflated and adherent to extraneous bodies; apertures large, distant, deep red, with five brighter spots within, and each placed upon a conic protuberance, with their margins hardly divided as in the other species by four or five valves; the conic protuberances are unequal, the surface in common with that of the whole body is rugous, of a grayish colour in some, of several new Species of Ascidia. $23 some, and brownish in other individuals, somewhat in appear- ance like a truffle (Tuber). —This species lives in society, attached to madrepores, rocks, shells, and each other; grouped with them are smaller ones, of nearly the same form, and of a beautiful red colour; but not having particularly examined these smaller specimens, I am not certain of their being the same species with their larger associates.—Length, about one inch and a half, by one inch in breadth.—Inhabits the bay of the Island of St. Thomas. 6. A. claviformis. Body small, sub-cylindric, elongated, larger towards the extremity, or sub-clavate, terminated by two small unequal approximate tubercles open at their sum- mit; substance gelatinous, diaphanous, glabrous. It lives in society, attached by the base to fuci and other marine bodies, and is also found thus attached floating on the surface of the water.—Inhabits the bay of St. Vincent in the West Indies. —Length about one inch, breadth 2 lines. 7. A. plicata. Body ovate, sessile ; swface sub-glabrous, but with many large inflated folds on the side of the inferior aperture, crossed by smaller folds, presenting on that side the appearance of small imbricated dilatations; the remaining part of the body is covered with much smaller folds; aper- tures approximate, unequal, terminal; but being much com- pressed by their position in the preserving liquor, I am unable to determine their natural form; substance opaque, readily yielding to pressure; colour white ; when air is forcibly intro- duced into the body, the latter becomes inflated like a small vesicle.-—Length about two inches.—Cabinet of the Academy. —This species was found attached to the bottom ofa vessel in this port. See Plate V. fig. B. 8. A. ovalis. Body sessile, resembling the preceding species, but smaller, less rugged, being destitute of large in- flated folds, with some slight, irregular wrinkles on the sur- face; apertures large, distant, placed at the extremity of two short, plaited tubes; the skin which margins the apertures is very thin, and apparently divided into many small obsolete angles; one of these apertures is placed lower than the other and lateral; colour, in the alcohol, white; nearly the size of plicata.—Cabinet of the Academy. The base of this specimen is surrounded by numerous in- dividuals of a species of Lepas, which covered the bottom of the vessel on which it was found. See Plate V. fig. A. 9. A. proboscidea, An elongated proboscis containing the two tubes; extremity obliquely truncated on each side; aper- tures subequal, placed on the summit of the proboscis, and separated only by a membrane, which extends the whole $32 length 324 Mr.C. A. Lesueur ov several new Species of Ascidia. length of the tubes, and projects a short distance beyond the apertures; colour white; surface glabrous.—I have seen the proboscis only of this animal, It was drawn up.from the bot- tom of an estuary on the coast of Georgia, by the fluke of an anchor, imbedded in mud and ‘fragments of shells. It was communicated to me by Mr. Say, as one of the interesting objects collected by Messrs. Maclure, Ord, Say and Peale, _on their voyage to Florida, and now forms part of the collec- tion of the Academy. 10. A. lobifera. Body sessile, subglobular, with approxi- mate, unequal apertures, concealed in the midst of many ir- regular fleshy lobes——This species, which I have seen only in the preservative liquor, was contracted, and appeared to me to have been somewhat proportionably longer in the living state. It seems to have been attached to a sand-stone.—The distinguishing peculiarity of this species, is the thick, fleshy and irregular lobes which defend the apertures. _ I think it probable that the apertures were capable of being elevated at the will of the animal, above the lobes which protect them when at rest. The colour in its present state is a dull black, and the surface is wrinkled.—Transverse diameter, one inch and a half, height also one inch and a half. List of additional new Species observed chiefly in the Pacific Ocean, during a Voyage of Discovery to Terra Australis ; Jrom the Manuscripts and Drawings of Peron and Lesueur. 1 Ascidia marginella, Decrés’, King’s and Josephine’s islands, in New Holland. 2 vermiculata, King’s and Decrés’ islands. 3 anatifoidea, Isle of France. 4 confederata, King’s island. 5 trinenta, bottom of Géographe bay, Leuwin’s land. 6 Jragum, Elephant bay, King’s and Decrés’ islands. 7 truncata, Bass’ strait. 8 rapuliformis, Endracht’s land. 9 gigantea, Bougainville’s bay, Decrés’ island. 10 lithopoda, Decrés’ island. 11 rhinophora,. Endracht’s land. 12 rosea, Bougainville’s bay, Decrés’ island. 13 alba, Bougainville’s bay. . 14 barbata, coast of Nice, Europe. 15 pilosa, Isle of France. 16 fasciata, do. 17 radiata, coast of Havre, Europe. 18 diaphana, King’s island. [islands. 19 phyllostoma, King’s, Decrés’ and Josephine’s 20 Ascidia Dissection of a Batrachian Animal in a living State. 325 20 Ascidia tetraodon, Josephine’s island, Napoleon’s land. 21 peniformis, Port of King George, Nuyt’s land. 22 australis, Oyster bay, in Maria’s island. 23 lithoidea, Leuwin’s land. 24 nigrita, Edel’s land. 255... rizophora, Napoleon’s land. 26 anthropocephala, St. Francis’ and St. Peter’s islands and port of King George. 27 nasuta, north-west coast of New Holland. 28 : _ democratica, St. Francis’ and St. Peter’s islands. 29 verrucosa, King’s island. 30 polystoma, do. LIV. Dissection of a Batrachian Animal in a living State. By Ricuarp Hartan, M.D. Professor of Comparative Anatomy to the Philadelphia Museum.* "pee specimen was sent from Georgia to Dr. Mease of this city. An account of a similar animal has lately been published under the name of “ Chrysodonta larveformis+.” ~ Having of late been familiar in the dissection of Proteiform animals, “les reptiles douteux” of Humboldt, and having had the opportunity of observing and dissecting this specimen in a living state, I experience less hesitation in making the following observations, more especially as the account alluded to above is by no means free from imperfection and error. The animal I dissected was eighteen inches in length (see Plate V. fig. C); the branchial cartilages are four in number, united to each other at their inferior end, but unconnected with the other parts of the skeleton; the branchial orifice is situate between the two inferior; the other cartilaginous slips are covered by the internal lining membrane: these orifices cannot be considered as connected with the process of respi- ration, are by no means breathing-holes, not being furnished with membranous fringes, and would appear to subserve no other purpose than to evacuate the water taken into the mouth with the food of the animal. The nostrils are small and situated near the point of the snout, they communicate with the fauces, opening immediately behind the palatine row of teeth. The lower jaw (fig. D. 8.) contains a single row of teeth of about thirty in number; the upper jaw contains a row on the # From the Journal of the Academy of Natural Sciences of Philadelphia, vol. iii. No. 2. for May 1823. + Vide Medical Recorder, July 1822, No. 19, maxillaries, 326 Dr. Harlan’s Dissection of a Batrachian Animal maxillaries, and another on the palatine surface, consisting of about forty in number; they point backwards, are very mi- nute, the tips reflect the golden rays, provided they be viewed through the medium of a microscope, they are not processes of the jaws, but are attached to the bones at their bases by a slightly moveable articulation, somewhat similar to the teeth of the shark: that is to say, neither by gomphosis or anchy- losis. On the top of the head are the orifices of two rows of glands (fig. D. «.), extending from the eyes to the tip of the nose: the eyes are covered with cuticle as in the Szren and Proteus (fig. D. y.) The tail is short, round at its base, and flattened vertically towards the extremity. There are no ribs, except the motionless rudiments, resem- bling in this respect the Proteus anguinus, and differing from the Szren and the Tritons, which have moveable rudiments of ribs. The fongue is cartilaginous, possessed of very little free- dom of motion. In the appearance of the circulating system, the alimentary canal, the cellular lungs, and the urinary organs, this animal presents no material difference from the Szven. The testicles are flat in this animal and cylindrical in the Siren. The parts about the region of the cloaca being some~ what mutilated, I was unable to determine exactly where the ureters entered the bladder. This animal cannot be considered, strictly speaking, as amphibious (breathing in air or water), not being furnished with branchiee, and is not calculated for progression upon land. Indeed the most remarkable peculiarity in its organization is its four boneless legs terminated by two toes, the external toe being the longest (fig. i and F). Whatever may have been the case during the early settle- ments of North and South Carolina, at present this animal is certainly rare, as none of our museums contain a single speci- men, nor was I aware that a specimen had ever been sent to Europe, until I was informed by Dr. De Kay of New York (atter having finished this description) that a similar animal had been noticed by Dr. Garden in Smith’s “* Correspondence of Linnzus,” under the name of Amphiuma means, on referring to which work I found that this animal had indeed been no- ticed under that name*. i t * Extract from a letter of Dr. Alexander Garden to Mr. Ellis, dated Charlestown, May 15, 1773. *« | have not as yet been able to procure another of the Amphiuma means, which he (Linnaus) calls Sireni simile. This appeared to me to be a still more in @ living State. 327 It will be observed that the description of Dr.Garden agrees with mine, with the exception of a few minor differences as respects the tongue, the pulmonary system, &c. Dr. Garden did not seem to be aware that the Amphiuma respired with two cellular lungs; by his own account, the specimen he de- scribed had been preserved in spirits, which circumstance will sometimes give rise to inaccuracies. From the above description, the Amphiuma must be ac- knowledged as generically distinct from the Batrachian animals hitherto described; the similarity of internal organization would place it between the Proteus and Siren. This very curious animal lived for several weeks in the pos- session of Dr. Mease, by whose request a drawing of the living animal was taken by Mr. C. A. Lesueur. To the former more singular animal than the Siren, as you might observe by my remarks,” &e. &c.—Vol. i. p. 599. In a letter to Linnzus, with which he sends a specimen, Dr. Garden gives the following descriptions of the Amphiuma: “T must now say something cf an unknown animal, which you will find in a glass bottle, and which I have no doubt will afford you much satisfac- tion ; the specimen here sent is the only one I ever saw, and I shall think myself fortunate if it reaches you in safety. “ When I first received it, the length was 37 inches, though the animal was then become somewhat contracted. At first sight I suspected it to be another species of Siren; but upon nearer examination I found so many differences, that there proves to be no relationship whatever between them. Can this animal form a link between the Lacert@ and Serpentes? is it al- lied to Anguis quadrupes? * Jt differs in many particulars from the Siren, most evidently in the fol- lowing. This animal has four feet, with two toes to each, without claws. The Siren has only two feet. It wants the gills and their wing-like coverings. It has no scales, nor, which seems to me very singular, any tongue! all which are found in the Siren. 1 have opened the throat, and satisfied my- self respecting the presence or absence of the gills. The following are the characters I have drawn up of this ugly animal. “ Head, rather long, depressed, tapering, serpent-like. * Mouth, extending half the length of the head. “ Lower jaw, furnished with a single row of sharp distinct teeth. “ Upper, with four rows with similar curved teeth. “ Upper lip, covering the under one. “ Tongue, none. Nostrils, two openings at the very extremity of the upper lip. ; > “ Eyes, dull, at the upper part of the head, on each side, covered with a thick tunic. “ A thin retractile membrane covers each cartilaginous lateral spiracle or orifice, by which the animal breathes. : “ Body, thick, nearly cylindrical, tapering and keeled at each side, be- yond the vent. Tail recurved. There is no dateral line. Vent, a large opening immediately behind the hinder legs. , “ Feet, four, two of them before, close to the spiracles, each with two toes destitute of claws, two behind, at the bottom of the belly, with similar toes. “ Inhabits deep ditches and lakes of fresh water.’—Vol. i, p. 333. gentleman, 328 Dr. Forster on the dispersive Power gentleman, who has shown himself on many occasions active in the cause of science, I am indebted for the opportunity of dissection. This specimen is deposited in the Philadelphia Museum under the name of Amphiuma means (Garden). [Norr.—For Descriptions and Figures of two Species of Siren, see Phi- losophical Magazine, vol. ix. p..118.—Ep1r-.] LV. On the Dispersive Power of the Atmosphere, and on the Peculiarities of Stars. By T. Forsrer. (Concluded from p. 210. | a late Number of the Philosophical Magazine, you did me the honour to insert some hasty observations on the varieties observed in the refracting and dispersive properties of the atmosphere, and on the nature of the light of several stars. The opinions therein stated are deduced from a num- ber of observations made and continually repeated by me, on the effects of refraction and dispersion. On different occasions, when I made the experiments and drew the natural conclu- sions from them, I was unaware that similar researches had been going forward on the continent, and also in Scotland, which I now learn to be the case; and I am also informed, that very similar facts to those which I have observed have been discovered by other persons, although, as it appears to me, by the employment of different means. At the time that I was in the southern parts of the continent in 1822, I was totally unaware that at that very time philosophers were investigating the nature and varieties of light and its refrac- tions in the clear atmosphere of the south of Europe. And being at that time engaged in the pursuit of objects more im- mediately connected with meteorology, I neglected to inquire after and to collect information as to what was going on in astroscopical science in the several observatories abroad. But I find that considerable advancement has been made in the knowledge of the peculiarities of the light of stars; and though I have not at present obtained any published details of the particular observations made, nevertheless have I learnt with pleasure from private individuals, that the results of such observations, made on a most extensive scale, have in a great measure coincided with my own imperfect attempts to illus- trate the singularities of different stars. I am at present un- acquainted with the different methods adopted by philoso- phers on the continent for separating and examining the se- veral coloured rays. But the method that I have chiefly em- ployed of the Atmosphere, and on the Peculiarities of Stars. $29 ployed is by the adaptation of the prism to the telescope and by the use of a chromatopoietic lens. I have tried several experiments with the prism adapted to different parts of the telescope, and I have tried various methods with the lens, which it is unnecessary to detail, as they are well known. After all, I believe the best way is for each observer to pur- sue his own method, and to give only the result at first; for if it should turn out by a future comparison of results, that any facts be ascertained by the employment of different means, then would the said facts be established on the firmest basis. I have myself employed several modes of observation, and they have certainly all agreed in this, that they have shown the same relative degree of oblongation of the spectrum, or the same apparent proportion of the coloured rays of each star respectively ; none of the different methods employed have contradicted each other*, and the variety in the results on dif- ferent nights of observation has been distinctly referable to the varieties in the dispersive qualities of our atmosphere, which I have already discussed in a former part of this me- moir. Making allowance for these slight varieties, which my constant attention to atmospheric phenomena has enabled me in many cases to foresee and prepare for, the same star in the following Table has always shown the same phzeno- mena. ‘Those stars which seem to vary in consequence as it would seem of some changes going on in their own proper light, or which are anomalous and incapable of being in- cluded in the same general view of the subject, have been put apart by themselves and will be mentioned hereafter. In the Table, column 2, I have put down the apparent colour of the stars, not only as observed in general with the naked eyes, but by the employment of another and very sim- ple method. I pushed the eyeglass of a four feet refractor gradually in, so as to let the rays fall on the glass before they came to a focus;—this method if applied to terrestrial objects in the day time would only produce confused images, and. utterly defeat the intentions of the beholder. From this cir- cumstance its use at night has been probably overlooked: for as applied to brilliant luminous points it is of considerable use. I usually pushed in the adjusting tube of the tele~ scope, till I obtained a large round spectrum of the star, so expanded that it occupied a large space in the field of view. This method will answer very well for all very bright stars, because what we lose in the dazzling intensity of the light * It was by an error of calculation that I placed Sirius first in the scale of refrangibility in my former paper in Phil. Mag. No. 311, page 208, Vol. 63. No. 313. May 1824. at when 330 Dr. Forster on the dispersive Power when brought to its proper focus, we gain in the duller and more easily observable expanded spectrum. ‘This me- thod, inachromatic telescopes, does not separate the different rays so as to produce an oblong and coloured spectrum ; but on the contrary, the large spectral disk which I have de- scribed, corresponds in its general colour with the colour of the star viewed with the naked eye; differing only in this, that the light not being intense or dazzling, we are enabled to ob- serve minuter differences in the colour of different stars viewed in this manner, than we could do if we Jet the rays arrive to the focus. This method is likewise useful for observing more accurately the permutations of colour noticed in the fluctua- tions of some stars, which I have before described. Since my last paper I have noticed more minutely the particular colours of the alternate changes in several stars, and have also ob- served some strange and unaccountable coruscations and ap- parent motions in the luminous striee of brilliant white light, which sometimes seems to intersect this pale and expanded spectrum described above, either in the form of lines, of radii, or of reticular intersections, leaving frequently dark spaces and unilluminated interposing lines. These coruscations have very much the appearance of some effects produced in arti- ficial electricity, or of certain coruscations of the Aurora Polaris. I hope on a future occasion to be able to communicate some further experiments on this phenomenon, as well as on an- other mode of observing stars with prisms, so as to get the black lines of non-illuminating rays at the regular intervals. But at present I am desirous to confine myself to the precise object of this paper, which is, to show the comparative refran- gibility of different star-light, and the necessity of tables of correction for each particular star of any considerable magni- tude. I have noticed that the red colour, which alternates in the fluctuation, generally, but not in every case, alternates with the ordinary or general colour of the star, stated in the fourth column. ‘This alternation is not distinctly observed in stars near to the zenith, but begins to be perceived very clearly at about 48° of altitude, and is greatest at between 10° and 15° above the horizon. When stars which are much subject to this alternation of colour are viewed at the above altitudes in the method above described, that is, by observing them before the rays come together in the focus, we not only observe more accurately and in an enlarged and less intensely luminous disk, the same phenomena that we can view with the naked eyes, namely, the sudden change of the whole star to deep red; but we may also distinguish that this red colour is not instanta- neously of the Atmosphere, and on the Peculiarities of Stars. 331 neously produced all over the star at once: it seems sometimes to ascend frum the lower limb upwards, like the drawing up of a curtain, or like the progressive ascent of light thrown on to a disk by the gradual inclination of a reflecting plane mirror, occupying (though the time is perhaps a deception of our organs) on different occasions + 3” of time in passing from the lower to the upper edge of the spectrum: but it does not recede again in the same direction; it suddenly seems to vanish, either leaving the disk of the star of its usual colour and brilliancy, or giving place to a blueish colour. In Sirius I have noticed that indigo, violet, and greenish white change with red. I have been enabled to determine the average number of the fits of redness in Antares as being three in 5” of time; and generally lasting from 2” to 1", though sometimes longer. In Sirius the red is paler, there is more variety, and the fluctuations are much more rapid. Another thing ob- served in the expanded spectrum is, that the intensity of the alternating red light, like that of the general light of the star, varies inversely as the size of the spectrum; so that instead of a deep and intense red, such as we see with the naked eye, or when we adjust the telescope to the proper focus; we see a more diluted red or pink light, alternating with other di- Juted colours according to the prevailing colour of the parti- cular star that we are viewing. I have not devoted a separate column for the colours and relative prevalence of the fluctuations of the stars, correspond- ing to the fourth and fifth columns of my last table, Philoso- phical Magazine, p. 208, as it seemed unnecessary. It may suffice to observe generally, that it is only certain stars which show this phenomenon in any considerable degree, and most of those have been before pointed out. ‘This coloured fluctu- ation, when observed in the prism, presents a very curious and beautiful phenomenon; and what is very remarkable is, that whatever colours any particular star may afford in the disper- sive lens, the same colours will be produced by viewing the star in an ordinary telescope, and simply vibrating it at the time of observation: and this led me to discover a new method of measuring the proportions of the colours, hereafter to be described. A great degree of fluctuation interferes considerably with our endeavours to estimate the refrangibility of different stars, founded on the dispersion of their colours ; because it makes the spectrum, as viewed in the glass, vary so perpe- tually, that we cannot easily measure the deviation of the eX- treme rays with the micrometer ; and therefore in stars which are liable to an inordinate degree of this fluctuation we must always make greater allowance for probable error. The third a te column, 832 Dr. Forster on the dispersive Power column, which is the most important, exhibits what I con- ceive to be the proportional retraction of the different stars severally, whose names are put down in the first column ; and this scale of comparative refraction is founded on the position laid down, and which I believe repeated experiment wil] con- firm,—that stars are more or less refracted according to the peculiar composition of their light: that is to say, in other words, the relative quantity of refraction of each star se- verally varies as the relative proportion of the more to the less refrangible rays of which their mixed light is composed. According to this position, it would seem that stars which appear to possess the red or less refractive rays would require a less, while those with a great proportion of violet would re- quire a greater correction than the mean refraction as stated in ordinary tables. I offer the following table with great deference to the re+ sults of other observations, and likewise with great caution, it being founded on an attempted measurement of the propor- tionate deviation and relative quantity of the differently co- loured rays in the several stars stated in the table. And I request that allowance be made for the great difficulty of such observations; and that the novelty of the experi- ments, the few opportunities that I have had of repeating them on an extensive scale, together with the great nicety re- quisite where small quantities are concerned,—may apologize for the rude and imperfect manner in which the observations have been conducted. If the future observations of more able persons should con- firm my own, I shall be glad to see them in detail: if they should be confuted, the very detection of the cause of the error may lead on to the knowledge of some other fact of use in the very curious investigations now going forward as to the nature of light. At all events they have afforded me, and may afford to others, agreeable amusement during the long and dreary winter nights of this miserable country. In the following table I assume the apparent altitude of the stars above the horizon at the time of observation to be 10°, and the barometer 0™°760:—the centigr. thermometer +10. Under which circumstances we may estimate the mean re- fraction as 5’ 19°10, according to the formulze determined by Laplace, and published in the Connaissance des Temps. Now presuming this to be the real mean refraction, and believing also that it equals the refraction of Capella, the figures put down in column 3 of the following table, indicate the quantities of refraction to be added to or subtracted from the above-men- tioned mean, in order to get the true refraction of each of the stars of the Atmosphere, and on the Peculiarities of Stars. 333 stars named in column 1. ‘Thus the stars which I have put above Capella in the column require a greater, and those be- low him a less correction for 10° of altitude than 5’ 19’°10, and probably in nearly the proportions indicated in the scale. The particular methods I have used, both for obtaining the spectra and for measuring the deviation of the extreme rays, being one I believe of my own discovery, and which I am not yet sufficiently confident in,—I do not at present think it ne- cessary to disclose, because I intend to make it the subject of a future communication. It has been overlooked, I am per- suaded, from its simplicity, in consequence of that fatal though common error of the human understanding, whereby we so frequently dig deep for the discovery of objects that lie near the surface and are overlooked. All I desire is, to learn from those who have better means than I possess of making the experiments, whether astronomical observations on those stars which are conveniently situated for determining the refrac- tion, shall be found to confirm or to refute what appears to have been ascertained as probable from the employment of a very different mode of investigation. TABLE. Propor. Refi. at 10° alt. Names of Star. Apparent estimating the prevailing Colour. mean Refr. as Blue Blue White Piya 08.55% ples ees. Sirtis 08 Arided ...... Attain: 25508 Procyon...... Rigel ......... Capella ...... Regulus... ... Arcturus. ... Alpliard...... Betalgeus ... Aldebaran ... Whitish Whitish Yellowish white Yellowish white Yellow Reddish white Orange red Reddish Red Reddish Observe: In the above table the quantities put down sare not asserted with any degree of positiveness, but are merely submitted, as being what the measurements of the various spectra seem to indicate. The 334 Dr. Forster on the dispersive Power The colour in the second column is merely the genera. appearance of the star as to colour when viewed in the man- ner already described, before the rays meet in a focus in the telescope ; and is of no particular utility, otherwise than by re- minding the reader of the-general varieties of colour of stars. I have not detailed the peculiarities of the coloured spectra, from want of time, and because the detail would take up too much space in your valuable Magazine. But I have given the results, as nearly as I could estimate them, in column 3. The following seems to be the order of the refrangibility of the planets: but I have not been enabled to state any propor- tions, as the principal method employed to disperse the light of the stars will not disperse that of planets. hether the Planet. Colour. Propor. Refr. is + or — the mean. TO cansnnicen Bright white. -f- Venus: ...cccss Bright white. + P Jupiter .......| Greenish-yellow white. | + ae” SAGUTMisisccace Dull white. = pean Mercury...... Reddish. I alee Mareen: gence Very red. —J Thus the Moon requires the most, and Mars the least cor- rection for refraction. ; I shall conclude this paper with some miscellaneous ob- servations on a mode of producing colours by vibration of the telescope; merely to show that by almost any means that we employ to separate the rays of starlight, the results show that stars differ from each other essentially in the composi- tion of their light, and that there is a correspondence in the results, of experiments of very different sorts; so that what we perceive is a real and not an imaginary difference. In a future paper I hope to present you with some curious observations on extraordinary or special refractions, which have happened occasionally in consequence of remarkable at- mospheric changes. I shall also send for a future Number, a Catalogue of Stars, on which no accurate observation can be made on their proportional refraction, and the causes why we cannot make them; as for example, Algol, Castor, Antares, and others. I write my observations hastily, and from my first impression of the subject, in order that I may induce others to observe and obtain information either in corrobora- tion or refutation of my notions. Vibration of the Atmosphere, and on the Peculiarities of Stars. 335 Vibration producing the primitive Colours. I have noticed a most remarkable method of separating the light of certain stars by means of rapidly altering the position of the glass. In order the more easily to explain this method, I must be a little prolix. The experiment of producing a ring of light like a circular band or wheel, by means of twirl- ing round a piece of lighted wood tied to a string, is well known, and is commonly practised by children. Now by causing the telescope to gyrate in such a manner, on the swivel on which it is mounted capable of being moved in all directions, as to cause the star viewed at the time to describe a circle; we obtain a luminous ring in the field of view of the telescope, instead of a luminous point. Now there is nothing very remarkable im this optical experiment, as far as it goes ; for we can produce various figures very easily, according to the direction in which we move the telescope at the time we are observing a star. Thus, if we move it rapidly from one side to the other horizontally, instead of seeing a luminous point, the star will appear like a horizontal line of light. If we gyrate it round and round, we shall view a circle of light ; and so on. This 'is easily understood, and the effect is com- monly referred to deceptio visus. But I have now to intro- duce to notice a very extraordinary phenomenon connected with this simple experiment. Observing Lyra one evening, while I gave the telescope the gyrating motion described, I noticed that the ring of light produced was not uniform in colour, as is the case when we twirl round a blue candle or a piece of lighted wood on a string. The ring of light pro- duced by the rapid apparent gyration of Lyra in the glass was separated into the prismatic colours, each colour seeming to occupy a certain portion of the circular ring of light. Now by observing which colour was most intense and occu-~ pied the largest portion of the ring, I endeavoured to ascertain the relative proportions of the primitive rays, as these co- loured portions of the ring seemed to correspond to the primitive colour of which the star is composed, and which we see when the light is separated by the prism adapted to the telescope. Thus the blue was the most conspicuous in Lyra: tor though the successive portions of the ring were red, yellow, green and indigo; yet all these colours were weak compared with the blue. I should have thought the whole of this phenomenon of no moment, had not the co- lours thus produced varied in the case of different stars. I tried the experiment immediately on the planet Mars, then favourably situated for observation; and I found that the Gas cular ‘ $36 Dr. Forster on the dispersive Power cular band of light which he produced, instead of being di- versified by the various colours, was always quite uniform, and resembled the light of his disk when viewed steadily in the ordinary manner. This discovery of the different results from viewing the planet Mars and the star Lyra in the same man- ner, gave additional interest to the experiment, for it showed that the colours were not the mere effect of the varying in- clination of the glass of the telescope. I then repeated the experiment on other stars, and on the planet Jupiter; the re- sults of which are as follows: Lyra produced the blue very strong, and the red, the indigo, the green and the yellow in successively less propor- tions. Spica Virginis showed nearly the same phenomena as Lyra, only the blue was still more preponderating. a Cygni showed a preponderance of indigo, less yellow and blue. Betalgeus produced yellow, and intense red and green. Sirius showed much indigo, violet, and portions of bright white light. Capella much orange, red, green, and less of the more refrangible colour. Aldebaran principally red, with some green and very faint orange. Arcturus produced a much less coloured ring than the others ; indeed its portions seemed to be orange and red running into each other. The planets Jupiter and Mars showed no colours at all; the rings produced by viewing them with a gyrating telescope, being only circles of light of the ordinary and uniform colour of those planets respectively. When any identical star was observed, the same colours were always produced in whatever direction I vi- brated the telescope :—thus a horizontal motion produced a horizontal rod or line, one end of which was red, the other blue, the middle green, and so on. I trust Ihave made myself understood, in this short and hasty account of a phenomenon which,—whatever may be its precise cause, or whatever may be the particular hypothesis in chromatics on which we may attempt to explain it,—certainly deserves future attention. For it must strike every body im- mediately, that however easy the explanation of the produc- tion of colours might be on optical principles, were the effects uniform, yet the following considerations must add great im- portance and interest to the experiments. 1. That the planets do not produce any colour when viewed by this method. 2. That the light of some fixed stars cannot be very di- stinctly separated by this method into the several colours, particularly Arcturus. 3. That the colours produced on the above method, seem generally to agree with those obtained by the adaptation of the of the Atmosphere, and on the Peculiarities of the Stars. 337 the prism to the telescope in the case of fixed stars, while in the case of the planets this method will not enable us to se= parate the light at all. - 4, That in rapid gyrations of the telescope, dark lines are produced, which intervene between the several colours: so that the circle appears broken, the several colours seem like separate portions of a circle of the same size, closely ar- ranged in the same orbit, and being separated from each other by narrow dark spaces. 5. That when this effect of the dark intervals between the colours takes place, we always observe other narrow spaces of intense white light, also interposed between the colours, and bordering on the dark spaces. 6. These dark spaces cannot be obtained distinctly from the light of Arcturus, and only in a very slight degree from that of Aldebaran and Betalgeus. The motion of the glass of the telescope through which the light of the star passes, certainly produces the colour; and this inclined me to think that the alternate colours before noticed are produced by some motion in the atmosphere, as I have hinted at in your Number for March, p. 198. Does the fact that Arcturus resembles the planets, in not affording the colours in any great degree, afford grounds for considering him as the nearest:of the fixed stars, and that di- stance of the stars is one cause of the disposition of the light to be easily separated ? I intend to offer some observations on the effects of refrac- tion and reflection combined, in a future Number. I have been at the trouble, lately, of comparing the declina- tions of the thirteen stars of the above table, as given by seven different observers; and I find that, generally speaking, the greatest differences of results have occurred in those stars whose proportionate refrangibility is the greatest and the least ; and that the differences of results have been the least in Capella and those stars whose refrangibility is nearest to the mean*. P. S. * I noticed with great interest the observation of Prof. Bessel respecting the habits of observing, as agreeing with what Maskelyne recorded of his very accurate assistant, who from August 1795 began to set down the transits 4’ of time later than hitherto, and continued to increase till he at length put them down .8," too late. This sudden alteration in the time of recording observations has occurred before. The causes of it lie deep in the nature of the mind itself, and, I believe, do not depend on the instruments, or on any derangement of the apparatus. When, however, we speak, as we must do in ordinary language, of such errors being in the mind, we say verylittle as to the particular cause of them. Astronomers in general may not admit, but am ersuaded those who are physiologists will be prepared to understand what eo going to say on this subject, which has long been in my mind. The Vol. 63. No. 313. May 1824. Uu error 338 Dr. Forster on the dispersive Power of the Atmosphere. P. S. I should like much to know the truth of an opinion I have heard broached, that Dr. Bradley deduced his tables of error is owing to an actual change in the brain, either from nervous dis- order and from increasing age, or, as J think may happen in some instances, from a change of activity from one to the other hemisphere of the brain- All the cerebral organs are double, and the organ of time among the rest. New, if the action of the hemispheres respectively does not exactly cor- respond, we may conceive an error to be invariably produced, by the left hemisphere, for example, taking the duty long performed, by the right hemisphere. For physiologists have shown strong reasons for thinking that the double organs do not both act at once; but alternate at long periods of time and thus relieve one another. Of course this explanation is conjectural, and only founded on analogies that none but phrenologists can readily enter into. Nevertheless, the discussion of these subjects is the best way to arrive at truth. And astronomers will excuse me for intro- ducing a subject not properly belonging to that science; since it tends to show the cause of the error complained of, and since the healthy condi- tion of our organs of sense and the brain is quite as necessary as Is the per= fection of optical instruments to correct observation. I may mention here another curious fact,—that if certam persons accus- tomed to observe with the right eye, begin to use the left, they at first are liable to put down an excess + of altitude, This has been explained, though unsatisfactorily, as follows :— The two eyes are seldom so’ exactly alike as that they shall both give the object viewed the same elevation ; although from habit when doth eyes are open we sce but one object. Now it may appear at first view, that this circumstance would not produce an error, inasmuch as all objects being elevated or depressed alike by each eye, the altitude of a star viewed with the left eye would appear at the same reiative distance from the horizon, as when viewed with the right eye, with which we had been accustomed to view it. This seems good reasoning at first, but the fallacy of it consists in this: that though when we change the use of the more to that of the less elevating eye, the distances of all the objects bear the same relative proportion fo each other, yet no particular object appears at the same relative distance, as it before did, from the place where we conceive the horizon or any other terrestrial objects to be, by the sense of touch. And this circumstance, unperceived by ourselves, creates a sort of confusion in the mind, that perplexes one in the record of small quantities, so as to produce error. The surplus of elevation given by one eye over and above that of the other, whatever inequality exists, may be measured, in cases where we can induce temporary double vision, or by looking alternately with each eye, or by looking through a telescope with one eye, and at the same object with the other eye naked. But the dis- cordance varies with the particular inclination of the eyes. Now I am dis- satisfied with the above explanation, because the use of the micrometer would prevent any such error from such a cause: and I am inclined to refer it to the parts of the brain in connexion with the eyes, called by the ag organs of space and size. For if those organs in one hemi- ere did not correspond in action to those in the other, a change to the use of the other side might cause the observer actually to perceive differently the quantities of space. The organs of the left side, for exam- ple, might not perceive such small quantities of space as those on the right. All this is very obscure and hypothetical at present, and we must be very careful not to perplex our observations of phenomena, by obtru- ding too hastily any theoretical explanations of their physical causes. retraction, Remarks on the Theory of the Kigure of the Earth. 339 refraction, chiefly by observation of Capella? If this turn out to be the case, it would become exceedingly curious, as by numerous experiments the refractions of Capella appear to me to equal the mean refraction, and that of Lyra and Aldebaran the two extremes. _ Hartwell, April 16, 1824. LVI. Remarks on the Theory of the Figure of the Earth. By J. Ivory, Esq. M.A. ER.S. qt is not my intention to trace minutely the various labours of philosophers on the Figure of the Earth, but to state concisely the present mathematical theory on that subject, and to add some observations upon it. 1. To whatever branch of the philosophical system of the universe we turn our attention, we are immediately led to the immortal author of the true theory founded on the law of uni- versal gravitation. Newton not only laid down the principles: he, in a great measure, reared the superstructure; or, at least, he sketched out so accurately the proper view te be taken of every part of the subject, that his followers have done little else but fill up his original outlines. The modern theory of the figure of the planets, still imperfect in some respects, coincides in the main with the physical ideas of Newton, which the progress of the mathematical sciences has enabled the philosophers of the present day to develop and extend. It is supposed in the Principia, that the earth is a mass of homogeneous fluid, the particles of which attract one another in the inverse proportion of the square of the distance. If there were no rotatory motion, the only figure consistent with the equilibrium of the attractive forces, would be a perfect sphere. But as the eartin revolves upon an axis, a centrifugal force is communicated to the particles of the fluid, causing them to recede from the axis, and changing the sphere into a figure oblate at the poles and protuberant at the equator. The preportion of the centrifugal force to gravity is easily found. Lvery point of the equator describes, in a second of time, a circular arc having its versed-sine equal to 0°67 of an inch; which is very nearly 7}, of 16;'; feet, the space through which a heavy body falis in the same time. Hence the cen- trifugal force is 74, of the observed gravitation; or y4z of the attractive force that would prevail if the earth preserved its figure and were at rest. In the question of the figure of the carth we may therefore suppose a sphere consisting of a homogeneous fluid, at rest Uu2 and 340 Mr. Ivory’s Remarks on the Theory and consequently in equilibrio; and we may inquire what change of form will ensue in consequence of a rotatory motion causing a centrifugal force very small in proportion to the gravity. ‘The problem is considered in this view in the Prin- cipia; but no investigation is given of the nature of the oblate figures that will have their particles iz eguilibrio by the action of the attractive and centrifugal forces. Newton tacitly as- sumes that the fluid sphere, in the nascent change of its form, will become a spheroid such as is generated by the revolution of an ellipse about the less axis. The meridians of the qui- escent sphere are thus, in the revolving figures, changed into ellipses having the greater axis in the equator. But whether this assumption was made merely because the ellipse is the most simple of oval figures, or for some other reasons, it would be in vain to inquire. Supposing therefore that the oblate figures caused by the centrifugal force are elliptical spheroids, we have still to de- termine the relation between the protuberance at the equator, and the observed velocity of rotation. Now this research is greatly assisted by the consideration that the spheroids are very little different from spheres. For, according to the general law that regulates the small variations of mathema-+ tical quantities, the centrifugal force at the equator and the dif- ference between the equatorial and the polar diameters, will al- ways have the same proportions to the gravity and the polar axis, so long as we can neglect the squares and other powers of the first two quantities. It is sufficient therefore to deter- mine what these proportions are in some given figure. New- ton takes the case of the spheroid that has the polar axis equal to 100 parts, and that of the equator to 101 of the same parts; and he computes that the gravity of a particle placed at the pole, is to its gravity at the equator as 501 to 500. He next supposes two columns ofthe fluid reaching from the centre of the spheroid, one to the pole, and the other to the equator; and as any two particles similarly placed in these columns will have their gravities in the constant proportion of 501 to 500, it follows that the total weights will be to one another as 501 x 100 to 500 x 101, or as 501 to 505. | Where- fore, if we suppose the spheroid at rest, the equatorial will preponderate the polar column; but, if we suppose a rotatory velocity sufficient to diminish the gravity of the particles in the equatorial column by its ;4, part, the weights of the two columns will just balance one another, and the revolving spheroid will be in equilibrio. Thus, when the protuberance at the equator is ;4, of the polar semi-axis; the centrifugal force requisite to the equilibrium is +45 of the gravity at the : equator, of the Figure of the Earth. $41 equator, the first fraction being 4 of the other. But, in the case of the earth, the centrifugal force is zap of the gravity at the equator; and hence, by applying what has just been proved, the equatorial protuberance will be 3 x 51.5, or 235 of the semi- axis of revolution. It follows therefore that the polar axis of the earth is to the equatorial diameter, nearly as 229 to 230. Newton’s determination of the figure of the earth is justly liable to objection in assuming, without proof, that the fluid sphere changes into an oblate elliptical spheroid by the action of the centrifugal force. It is also defective in considering only the extreme case of a fluid mass perfectly homogeneous, It even appears that the illustrious author had not reflected with his usual accuracy on the consequence of an iacrease of density towards the centre; for he supposes that it would be attended with a greater oblateness of the spheroid; which is contrary to what actually happens, as was first proved by Clairaut. 2. Huyghens considered the figure of the earth in a diffe- rent point of view, which deserves to be mentioned on account of its connection with the true theory. His attention was first drawn to this subject by the variation in the length of the seconds’ pendulum in different latitudes, which was discovered by Richer in 1672. Huyghens immediately perceived that this phenomenon was caused by the centrifugal force at the earth’s surface; which increases in approaching the equator, lessens the power of gravity, and retards the time of the pen- dulum’s vibrations. It also occurred to him that if the earth was a perfect sphere, a plumb-line would not be at right an- gles to the sea, or to the surface of standing water, but would be drawn a little aside from the perpendicular by the centri- fugal force. Hence a light body in still water would not press perpendicularly upon the surface, and consequently could not be at rest; which is contrary to experience. Huy- ghens therefore argued that the earth was not spherical, but protuberant at the equator, in order that the terrestrial meri-= dians might be every where perpendicular to the plumb-line, He seems not to have carried his speculations on this subject further, till after the publication of the Principia; when, by adopting Newton’s method of equalizing the weights of all the columns reaching from the centre to the surface, he was enabled to determine the figure of the terrestrial meridians. His solution of the problem was first published in an Ap- pendix to a posthumous tract on the cause of gravity. Re- Jecting the Newtonian principle of an attraction between the particles, he places, in the centre of the mass, a force attract- ing the particles with the same intensity at all distances; “a ne 342 Mr. Ivory’s Remarks on the Theory he proves that a homogeneous body of fluid revolving upen an axis will be zn equilibrio when it has the figure of an oblate spheroid very little different from a sphere, the ellipticity be- ing 4 of the proportion of the centrifugal force to the gravity at the equator. In the hypothesis of Huyghens the ellipticity of the earth would therefore be }x 45, or 544, instead of zia Which it is in the theory of Newton. The centrifugal force remaining very small in proportion to gravity, if we suppose that the attractive force placed in the centre varies as some power, or even as some function, of the distance, we shall still find the same ellipticity as when the central attraction acts with the same intensity at all di- stances. For, cn account of the near approach of the figure of equilibrium to a sphere, the variations of the central force at the surface will introduce into the equation of the spheroid RO quantities but such as are of the second order, which are to be neglected. In the Newtonian law of attraction, if we suppose a re- volving fluid mass, which increases in density towards the centre, to be in equilibrio, it is proved that the ellipticity will be less than in the case of a homogeneous fluid; and the dense we suppose the matter near the centre, the more will the ellipticity decrease. If the matter at the centre be infi- nitely dense, we fall upon the hypothesis of Huyghens; which is therefore one extreme case, the other extreme being the supposition of a homogeneous fluid. The ellipticity of Huyghens, or 4 the proportion the centrifugal force to the gravity at the equator, is therefore the least. possible; and that of Newton, or 3 of the same proportion, is the greatest. It is extremely improbable that Nature will coincide with either of the extreme cases; and accordingly all the observa- tions agree in giving the earth a mean figure between the twa limits. 3. About 48 years after the publication of the Principia, Mr. Stirling communicated to the Royal Society of London two elegant propositions, in which he proved the legitimacy of Newton’s investigation of the equilibrium cf a homogeneous fluid revolvymg about an axis. Two years afterwards Clairaut, in two papers sent to the same learned body, treated the same subject more fully, demonstrating the accuracy of the conclu- sions obtained in the Principia, and extending his researches to spheroids composed of strata of different densities. In 1740, or 53 years after the publication of Newton’s work, Mac- laurin’s Dissertation on the Tides appeared, forming a re- markable epoch in the history of this department of science. He proved, by the most elegant and accurate geonietry, that a homo- of the Figure of the Earth. 343 a homogeneous fluid mass, having the form of an oblate ellip- tical spheroid, will be zn equilibrio, when it revolves upon its axis in a proper time. ‘The attractive forces acting at every point of the spheroid; the rate of the diminution of gravity from the pole to the equator; and the relation between the ellipticity and the centrifugal force; are all determined with great simplicity and elegance. It follows from the researches of Maclaurin that, for every degree of ellipticity, there is only time of revolution; but D’Alembert, considering the equation between the ellipticity and the velocity of rotation, afterwards found that, when the latter quantity is given and the former is sought, the problem admits of two different solutions. In 1743, Clairaut published his Théorie de la Figure de la Terre. ‘This is a work of the greatest merit and elegance, containing many new results, and treating every part of the subject in a full and satisfactory manner. In the case of ho- mogeneous spheroids Clairaut abandons the method followed in his first researches, and adopts that of Maclaurin. But, with respect to spheroids composed of strata of different den- sities, he admits the hypothesis of a small ellipticity, which simplifies the investigation, and is sufficiently exact tor deter- mining the figure of the planets. In all these researches the oblate elliptical spheroid is alone considered; and the question is to prove that it will be iz equilibrio when it revolves upon its axis. Maclaurin solved the problem generally and accurately in the case of the ho- mogeneous spheroid. In all the other solutions the supposi- tion of a very small ellipticity is admitted; and therefore the results are approximately, and not rigorously, preved. But the theory was imperiect unless the investigation could be ex- tended so as to take in all the possible figures of equilibrium, or until it was shown that the elliptical eueeand alone fulfilled the conditions. This brings us to the researches of Legendre and Laplace; but as the discoveries of these eminent geome- ters were deduced from the hydrostatical theory of equili- brium, it is necessary to notice briefly the progress made in this part of the subject. 4. When the effect of the centrifugal force to shorten the seconds’ pendulum in approaching the equator, was first dis- covered, Huyghens immediately inferred that the terrestrial meridians were not circular; and, in order to determine the true figure, he assumed the principle that they must be Mitendiculsr to the direction of gravity. Newton investi- . gated the figure of a homogeneous fluid turning upon an axis, by 344 Mr. Ivory’s Remarks on the Theory by equalizing the weight of all the columns of fluid drawn from the centre to the surface; ‘There is no doubt that both these conditions are indispensable to the equilibrium of a fluid mass. But Bouguer remarked that they were not al- ways reconcileable in the same figure; and hence he con- cluded that those figures only were zn equilibrio in which both the conditions were fulfilled. Clairaut afterwards showed that the equilibrium of a fluid was not always ensured even in those cases when both the principles of Huyghens and New- ton led to the same figure. Maclaurin adopted the more general and undoubted principle, that every particle is in equilibrio when it is pressed equally in all directions. But we are indebted to Clairaut for the discovery of the general equations of the equilibrium of a fluid mass, whether homo- eneous, or composed of parts of different densities. Finally, uler brought this theory to the more simple form in which it is now taught, by deducing the equations of Clairaut from the principle of an equal pressure in all directions. The conditions required by the hydrostatical theory for the equilibrium of a fluid mass are these: 1°. All the par- ticles of the same density must be arranged in distinct strata. 2°. The resultant of all the forces acting upon a particle must be perpendicular to the level stratum, or couche de niveau, in which the particle is placed. ‘These conditions will be ful- filled if all the level strata be defined by the same equation, the arbitrary quantity introduced in the integration alone varying from one stratum to another; and the same quantity representing always a certain function of the density. In tlie case of a homogeneous fluid, the distinction of the level strata arising from the difference of density is lost; and then the only conditions requisite to the equilibrium are con- tained in this proposition: The resultant of all the forces acting upon a particle in the outer surface must be perpendi- cular to it; and the differential equation of the same surface must be an exact fluxion. Now if, with Newton, we suppose a sphere of a homoge~ neous fluid, originally at rest; and inquire what will be the nature of the oblate figures produced by the rotation upon an axis; it is manifest that we shall only have to fulfill the single condition, that the gravity be every where perpendicular to the meridians. ‘This problem was first solved by Legendre in 1784, but only upon the supposition of a very small oblate- ness. After the lapse of a century, the conditions of equili- brium assumed by Newton were thus not only verified, but completely demonstrated; since it was shown that the equili- brium of the Figure of the Earth. 345 brium is not possible but when the fluid has the figure of an elliptical spheroid. Laplace generalized and perfected the analysis of Legendre, which is founded on the properties of a par a kind of functions. ‘The same illustrious geometer ikewise discovered an equation in partial fluxions relating to the attractions of spheroids little different from spheres, which takes place at their surfaces. Availing himself of all these resources, Laplace was enabled to give a complete theory of the figure of the planets, and of the variation of gravity at their surfaces, which the reader will find explained at length in the third book of the Mécanique Céleste. 5. On reviewing all-the researches relative to the figure of the earth, it is remarkable that the discoveries of Maclaurin stand apart by themselves, without much connection with the rest. His method applies only to homogeneous spheroids ; but of this case it furnishes an accurate and a general solu- tion. All the other attempts to solve the problem are merely approximations founded on the supposition that the spheroids are not much different from spheres. As was observed by Mr. Stirling, they do not accurately determine the figures of equilibrium; they only show that these figures will coincide with elliptical spheroids when we neglect the squares. and higher powers of the ellipticities. f the conditions of equilibrium assigned by the hydro statical theory were accurate and sufficient, we should expect that the discoveries of Maclaurin would be deducible from them. Yet this has been accomplished by no geometer. Nay, when we push the approximation to the figure of equi- librium beyond the quantities of the first order, the ellip- tical spheroid seems to be excluded. It also appears unac- countable that the solution of Legendre, supposing that it is deduced from a sufficient theory, should bring out only by approximation a figure which we know will accurately fulfill all the conditions. These reflections, and others which it is not important to mention, induced me to examine very narrowly the hydro- statical theory of equilibrium. I-distinguished two separate cases; one, when there is no attraction between particle and particle; and the other, when the particles are endowed with mutual attractive powers. As an example of the first case, we may take Huyghens’s hypothesis respecting the figure of the earth; in which every particle of the fluid is acted upon by a centrifugal force, and a constant attraction directed to the centre. ‘The equilibrium of the revolving mass requires that the resultant of the two Vol. 63. No. 313. May 1824, Xx forces 346 Mr. Ivory’s Remarks on the Theory forces acting upon every particle in the outer surface, shall be perpendicular to that surface; and we may suppose that this condition is expressed by the a ai =; where ¢ is a function of the three rectangular co-ordinates of a point in the surface, and C an arbitrary quantity introduced in the integration. All the level surfaces will be determined by the same equation, the function ¢ remaining the same, while C decreases by insensible degrees: whence it follows that the resultant of the accelerating forces will be perpendi- cular to every level surface; and that every level stratum will press equally upon the fluid below it. In this first case there- fore, in which the level strata act upon one another only by pressure, there is no doubt that all the conditions of equili- brium are contained in the equation of the outer surface; which is agreeable to the received theory. We may next suppose, as in Newton’s theory of the earth, a homogeneous fluid mass subjected to a centrifugal force, and to an attraction between the particles in the inverse propor- tion of the square of the distance. The condition that the re- sultant of the accelerating forces is perpendicular to the outer surface, will, as before, be expressed by an equation, viz. and the several level surfaces will be determined by makin € decrease ‘by insensible degrees. In the interior of the fluid body, the gravitation, or the resultant of the accelerating forces, at any level surface, will be perpendicular to it; and hence the thin level stratum immediately above, will press equally apon the fluid below. But it is to be observed that the pres- sure is caused by the gravitation at the level surface acting upon the matter of the thin stratum above, and that it is inde- pendent of any active forces inherent in the matter of the stratum. Wherefore, since every particle attracts every other eghre the level stratum will act upon the fluid below it oth by pressure and by attraction; and, in this respect, there is an essential difference between the present case and the for- mer one. There are here two distinct forces independent of another; and the adjustment of the equilibrium requires that both be taken into aceount. The equality of pressure is a consequence of the equation of the outer surface; but the equilibrium with respect to the attractive forces of the stratum can be obtained only by supposing that the stratum has such a figure as to attract all particles in the inside with equal forces in opposite directions. The received theory is there- fore defective and insufficient in the case of a homogeneous fluid of the Figure of the Earth. 347 fluid consisting of attracting particles. The full conditions requisite to the equilibrium of such a fluid mass are these: 1°. The resultant of the accelerating forces must be perpen- dicular to the outer surface, and the differential equation of the same surface must be an exact fluxion; 2°. Every level stratum must be possessed of such a figure as to attract all particles in the inside with equal forces in opposite directions. Let us now consider the equilibrium of a fluid mass diffe- rently; in the method of Euler, and as it is treated in most of the elementary works. For this purpose we must find the conditions requisite to the equilibrium of a rectangular paral- lelopiped of the fluid placed any where in the mass. The forces in action are: 1° the pressures upon the six faces tending to compress the fluid into a less space; 2°. the acce- lerating forces acting upon the particles of the parallelopiped. If the latter forces be resolved into three sums perpendicular to every two faces of the parallelopiped; it is obvious that each sum must, in the case of an equilibrium, be equal and opposite to the difference of the pressures upon the same two faces. Three separate equations are thus formed; and by combining them, we deduce the value of the differential of the pressure; and again, if we suppose the pressure constant, we obtain the equation of the level surfaces. Nothing can be clearer or more simple than this procedure, when there is no attraction between the particles. In this case it is unquestion- able that all the forces in action are taken into account, and no objection can be made to the accuracy of the result. But when the particles attract one another, some reflection will show that there is an omission. In estimating the accelerating forces, the attraction of the exterior matter upon the paral- lelopiped is alone considered, while the attraction of the par- ticles of the parallelopiped upon the exterior matter 1s neg- lected. Although it is supposed that the parallelopiped is in- definitely small, yet, as the attraction of its particles is ex- tended to all the fluid mass, an accumulated force is produced comparable to the pressure, and which must not be omitted in adjusting the equilibrium. When all the forces acting upon the parallelopiped; both those extrinsic to 1ts own mat- ter, and those inherent in its particles; are taken into account, the same conditions of equilibrium will be obtained that have already been found by the former investigation. The proofs of the new theory of the equilibrium of a fluid consisting of attracting particles, are fully detailed in a paper sent to the Royal Society in November. last, and which will appear in their Transactions for the present year. Having Xx 2 obtained 348 M. Bessel’s Examination of the Divisions obtained the true conditions necessary to the equilibrium of a homogeneous fluid, there is no longer any difficulty in de- ducing from them what was proved synthetically by Maclau- rin. The peculiar analysis of Legendre and Laplace is no more than a modification of the exact equations of the equili- brium, when we neglect the square and higher powers of the oblateness of the spheroid. In those remarkable propositions, which never can be too much admired, where Newton treats of the attractions of spheres and spheroids, he proves that a particle placed any where within a hollow spherical shell uniformly dense, will be in equilibrio, or will be attracted equally in opposite direc- tions. The same conclusion has been extended to a hollow shell of homogeneous matter bounded by any two elliptical surfaces similar to one another. This curious property is noticed by all the writers on attraction; but it seems to be viewed as belonging accidentally to elliptical spheroids. The new theory shows its connection with the equilibrium; for the hollow shell is no other than a level stratum of a homoge- neous fluid in equilébrio. The paper above alluded to treats only of homogeneous fluids. But the same principles likewise apply when the mass is composed of strata of variable densities, as I shall be able to show on another occasion. A great advantage arises from knowing the true equations of equilibrium, in hoketes the demonstrations, and in clearness and precision. When the equations can be solved, the exact figures of equilibrium are obtained, as in the case of a homogeneous fluid; otherwise, the analytical method of approximate solution must be em- ployed. James Ivory. ay 5, 1824, LVII. Examination of the Divisions of Rercuensacn’s Circle at the Observatory of Kénigsberg. By M. Brssr..* | HAVE applied to this instrument the same method by ; which I have formerly determined the errors of the divi- sions of Cary’s circle, with such changes only as the nature of its construction required. Cary’s circle is read off by micro- scopes, and one of them, together with another expressly con- structed for the purpose of examination, is sufficient for in- vestigating the errors of division. Reichenbach’s circle has * Translated from the viith section of M. Bessel’s Astronomical Obser- vations, no of Reichenbach’s Circle at the Observatory at Kénigsberg. 349 no microscopes, but verniers; and instead of one additional microscope, two must be applied. But these microscopes can- not be fixed any where but on the alhidade circle; and from this circumstance a change of the angle between them may arise, for the alhidade cirtle is attached to the principal axis of the instrument; and as there must always be a little play between this axis and its collar, their centres will not always coincide; and this accidental eccentricity will be mingled with the errors of division which are the objects of investigation, and destroy the accuracy of their determination. In order to avoid the effect of this eccentricity, it is necessary to deter- mine the means of the errors of points diametrically opposite, which may be done by means of four microscopes so placed that two diameters determined by them inclose the angle which is to be examined. An apparatus of this description, made by M. Pistor, has been used on this occasion; the mi- croscopes are so constructed that by proper solid clamps they may be fastened to any point of the alhidade. I have in the first place determined the angles from 15° to 15°; next I have bisected these angles; and lastly, again bisected the angles of 22°-30, and thereby determined all the errors of the divisions of those diameters which belong to multiples of 33°; for every diameter I have taken the mean of the two divisions which be- long to it and likewise the preceding and following ones, so that each diameter is determined by the mean of six divisions, In order to obtain the angles of the form 2. 15° with the on accuracy, and free from all accumulation of error, I ave changed the position of the microsopes four times, mak- ing the angle between them successively 60°, 45°, 30° and 15°, In all these positions the first microscope was placed on the points 0°, 15°, 30°,...330°, 345°, and the other three micro- scopes read off; each of these four sets of observations was repeated on three different days in sueh a manner, that the angles were brought under the microscope, not in any regular succession, but entirely without any order, by which means I intended to destroy the effect of a change of temperature of the instrument. I denote the error of division of the point u of the circle with the sign with which it is to be added to the - reading of the circle by ¢u and 4[¢u+9(180°+u)] by pu; eeably to this notation the single sets of observations have given the following results. The 345) —0:05| —0-62) —0:78 u, u+30, u+180, (u+60)—Lu 0} —0-02; —0-46, —0-15|—0-21 5} +1-05| +1-00| +0-95|+1-00 +1-22| +.0-33| +.0-69|-+0°75 +0:48) + 0°42) +0:52 41°50) +1-01) +1:52|4.1°34 —0°36| —0-71| —0-11\—0°39 +0-62| +0-58| +0:32|4.0°51 —0-64| — 1-03} —0°79 — 0°89} — 0-55] —0-61|—0°68 —0-70| —0:04| —0-97 —1-42| —0-93| —1-19|—1'18 5| +0-16| +0-48) +0 47|+037 —044| —1-19) —0-34 5). + 1-40] + 0-88} +1-03)4+ 1°10 10" +1-36| +.2:55| 4.1-19]4.170 0-00] —0-52| +.0-27|—0 08 +0:20| +.0-64| —0-07| 40°26 5| —0-55| —1-07| —0 97|—0°86 —1°51} —1°37| —1-62|—1°50 — 1-39] — 0°63) —1-18|—1°07 —1-55| —0:94| —0 96)/—1°15 The microscopes are on the points |The microscopes are on the points u, u+60°, w+180°, u+ 240°. ‘ Lu+30—Wu. u+210. ~u_ |July25.|July26.|July30.| Means. 6| —0:37| — 1°13] —0-44] —0-65 15| +1-22] +.0-84] +0-87| +0-98 30| —0°38) +0-07| —0°17| — 0°16 45) +0:12) +0:29| +0°54/ +0°32 60| 4 0-34) +1 40) +.0-94] 41-06 75| +.0:07| +0:11| 40-05) +.0-08 90) 4 0:09| + 0°62 + 0°53) 40°41 105} _0°19 40°07 — 0°20) — 0°11 120 +031 —0°31| —0:01} 0:00 135| — 0°51) — 0-13} —0°69) — 0°44 150) — 0°64) — 0-52) — 0°35) — 0°50 165} —0°22) — 0°35) +.0:20) 0-12 180| 40-08] —0-07| — 0-40) —0-13 195| 41°33) 41-20] 41-24) 41:26 210} —0°31| — 0-23) +.0°36; —0-06 225| — 0-54) +.0-26, —0-05| —0-11 240| 4.0:92| + 0°54| 40°67] +0-71 255| 40-29] 40:13 +0-25| +.0-22 270} +.0°32) 40-29, 40-42) +.0-34 285] —0°74| —0°72) —0-07| —0°51 300| —0-38| —0-04) —0:63| 0:35 315} —0°77| —1°10) —1°37| — 1:08 —0°46)' —0°62 —0°91| —0°66 u 5 u+45°, u+180°, u+225°, Wu+45°)— Lu u \July22.'\July23.|July24.) Means, °o uw “ “wn “" 0| 40°39] +0-76| +.0°92| +0-69 15| —0-17| — 0-18] +.0:27| —0:03 30) 40°89] +0:77| —0-01| +.0°55 45| 4 0-44| —0-19| +0:53| +.0:27 60| +.0:88) +0:36) +.0-82| +.0°69 75) +1:35| +0-98| 41-21] 41°18 90| — 0-06, +.0:26| —1-14| —0°31 105| —0-65| +.0°36| +.0-20) —0-03 120| —0:59| —1-61| — 1-36] —1-19 135| —0-40| — 1-28] +0-04| —0-21 150} —0:93) —1:10, —1-48| —117 165| —0-09| —0-22| +0-27| —0-01 180| +059] + 0-76) +.0-93| +0-76 195} 40-83] +.0:28| +0-51| +0°54 210] +.0°31|“£.0-73) +037] +0-47 225| —0-50| 1-44, —0-95| —0-96 240] +-0°86) 4 2-04) +-0:33) +1-08 255) +114) 4 0-33] 40°88) +.0-78 270) +-0°33) +.0°51) +. 0°14) +.0°33 285| 40°43, —0-15| +.0-42| +023 300| —1-75) —0:53| —0-56, —0-95 315| —0-80, —036 —0-49| —0°55 330| —1-24) —1-6]| —1-08, — 1-31} 345] —1-25| 0-46, —0°81| —0°84 uw» u+15°, u+180°, 2+195°. ut 15°— Wu. wu |July3l.jAug. 1.jAug. 2.|Means. ° “ Z 4 “ 0) — 1-07; —0:98; —0:24 —0-76 15] +0°81] +-0°34) +0-65| +0°60 30| +0°64) +0°52) +0 25 +047 45) —0°57| —0°51) —0°48) —0°52 60} + 1-53) +1:06) +1-02) +1-20 75| —0'15| +0-26| +0-21 40-11 90} + 0:17}; —0°01| +.0-23) +013 105| +.0-79| +.0°10} +0°59| +0-49 120} —0:17| — 0°16) —0°74| —0°36 135| —0-11] +010) +.0-09} +.0-03 150) —0-96} —0°93) — 1-08) —0-99 165| +0-49] +.0°39| —0-03) +-0-28 180) —0°33} —0°58) —0°99| —0-70 195} +0:24| 4+.0:06| +0-09} + 0:13 210} +0°67| +-0°93) +0°95) +.0-85 225| —0°48] —0-70| —1:01| —0-73 240} + 0°75] +-0°89} + 1:19) +.0:94 255' —0-08) +0:08) +0715) +.0°05 270| +0°19| +.0-44) +.0°47! 40:37 285] +.0°24) +0-20| +018 +0:21 300) —1-10} —0:94 — 0°69) —0°91 315) 0°00) +0°36, +0:33 +0:23 330, —1:15 —1°05) —1°31| —1-17 345) —0:20) +015] +017 +0:04 M. Bessel on the Divisions of Reichenbach’s Circle. 351 From these observations the most probable values of the errors of division:are to be deduced; their number is 24, but Yu being equal to ¥(u~+180) they are reduced to 12, one of which may be assumed arbitrarily; I supposed YO=180=0, and obtained, by a solution adapted to the present case of the 11 equations resulting from the method of least squares, the following values : In order to appreciate the accuracy of these determinations, I remark that every error of division is as accurately deter- mined as if it had been derived from 30°42 observations of an angle between two diameters (referred to six divisions) or 91°26 single positions of the microscopes; I find by all obser- vations the probable uncertainty of a single reading of the microscopes to be = + 01825; and therefore the probable error of }(m 15°) = + 0”0191.* This great accuracy is a con- sequence of the clearness and neatness of the divisions, the excellence of the microscopes, the regularity of their screws, and the solidity of their fastening; but at the same time the frequent repetition of the determination of the angles and their numerous crossings was necessary, in order to carry the ac- curacy so far beyond the limits of the accuracy of a single observation. All errors in these observations being contin- gent, the accuracy may be carried to an unlimited extent, certainly much further than the artist has carried it in making the divisions: the astronomer who examines his instrument according to my method, has the great advantage over the artist who divided it, that he can repeat the operation as often as he pleases; whereas the artist has to depend on the single operation of setting the apparatus for cutting thedivisions,which may be done according to the quality of that apparatus with greater or less accuracy, but never with absolute correctness. In order to determine the“angles of the form 2 15°+7° 30%, I have placed the microscopes at angles of 7° 30’ to each other, and have derived the errors from a comparison with the pre- ceding and the following numbers of the foregoing table: in #7 01825 ane O-0191.—Transt. ) this M. Bessel’s Examination of the Divisions this operation the circle made two entire revolutions, and every angle was determined eight times as follows: u- o | o./ 7 30) 187 30 22 30| 202 30 37 30/217 30! 52 30) 232 30 67 30) 247 30) 82 30} 262 30 97 30) 277 30 August 5 and 6. Pei meal nel —0°60 —0 74|—0°82|—0°59 | ~0-41|—0:27| 0-26 | — 0°05} —0:09/} —0°33 |—0°03'-+0°16 +0:44 +0:52/40:43)+0°61 \+0°35 +0°45|+0°53 ° | 4) i —0°40!— 0°40] —0°32 — 0°60} — 0-24} —0°51| — 0°60; —0°34 —0-40]—0-39|—0:02 —0-30j—0°45|—0-31 +0-25!+-0-04|—0-05 +0°70)+ 0°17|/+ 0-49 4+ 0:43'+0-60|-++0-62 112 30) 292 30| +1-52 +1-08|+ 1-25) + 1-60! 41-29] + 1-09 127 30 307 30|+ 0-11 + 0-25] + 0:25|-+.0-12| —0°12| 0-03 142 30 322 30 +1:12 +1°09}-+0-98| + 1:21;-+1-35|+1-20 157 30| 337 30 +-0-46 +0°12) —0-02) + 032} +-6-37| 0-14) —0°13| + 037} +0°169 172 30 352 30 — 0-32 —0-64| —0:59| — 0-28! —0-44] — 0°59 —0-34|—0°18!—0-423 Probable error of each mean = + 00396. For determining the angles of the form m 15° + 32°, the microscopes were placed at angles of 11° 15’ to each other; the observations were not continued beyond one revolution or the fourfold repetition of the angles. I obtained the following errors of division: August 9 to August 12. August 9 to August 12. Means. 7] “ nO “ —O11 +0°07 | +0°03 | —O:15 +053 | +0°60 | +0°85 | +0:78 | +0°90 | +1:16 | +097 | +091 +149 | +1:03 | +076 | 41°21 +0°49 | +046 | +953 | +0°56 +047 | +053 | +0°61 | +0°56 +101 | +076 | +062 | +0:87 + 0°37 | +0°32 ] +0°50 | +0°55 —0°72 | 0°79 | —0°42 | —0:34 —0'15 | —0°40 | —0°57 | —O31 —0'07 | —0°30 | —0°13 | +0°10 -—O19 | —O'41 | —0710 | +012 Probable error of each mean = + 00698. The of Reichenbach’s Circle at Kénigsberg. 353 The following table contains all the errors of division suc- cessively found: “i j ‘ U 0 0°00] 60° dj240° 6|—0'50]120° 01300° 0 | +.0'38 3 45/183 45] —0°26 } 63 451243 45/—0-12}123 45/303 45} +0°51 7 30/187 30) —0°46 | 67 301247 30/+40-18 127 301307 30/+ 0°18 LL Loj19L 15) — 1-08 | 71 15}251 15\+0-40f131 15/311 15 40°54 15 01195 0} —0°72] 75 0)255 0/40:37]135 01315 0/4017 18° 45/198 45| —1°49 | 78 45}258 45/4+.0-68]138 451318 45 | 40°82 22 30/202 30} —0'55 | 82 30}262 30/+0-48 f142 30\322 30/+ 1-20 26 15/206 15) —0°34 | 86 15]266 15/+0-77}146 15/326 15|+0-43 30 0/210 0)| —0-44} 90 0]270 040:331150 0/330 0|+0-60 33 45/213 45) +0°19 | 93 45}273 45,\—0-041153 451333 45 |—0°57 37 30/217 30) —0°23 | 97 30)277 3040-53 j157 301337 30 |+0°17 41 15/221 15) —0-06 j1OL 151281 15 +0-69}161 15/341 15|—0-36 j 25 0} +0:32 1105 01285 0+40-481165 0345 48 45)228 43) —0-44 i108 45]268 45 +0°99 [108 45/348 45 |—0-10 52 30/232 30] —0-31 hig 30)292 30\4- 1°23 4172 30\352 30|—0-42 56 15/236 15) —0-44 $116 15)296 15 -+1:121176 15'356-15|—0-14 60 0/240 0}/—0-50:120 01300 0-+0-S8]180 @ © 0| 0-00 a (=) | ° ey wo These errors, however small, present some regularity: the greatest part of them might be represented by the form a sin (A+ 2u), and be accounted for by an elliptic form which the circle may have assumed by carriage and by being screwed to the axis. There is, however, no perfect regularity, nor could it be expected, as in each diameter the mean ‘of the contingent errors of six divisions must considerably disturb any regularity which might exist. The value of the contin- gent errors of the divisions I have endeavoured to determine, by comparing the mean of the three divisions employed for every point with each individual division; by this means I have found the probable deviation of every division from any law = + 03251. It follows from this number, which de- pends on the examination of 288 divisions, that according to the laws of probability there are among the 7200 divisions of the circle, ‘ ys 2352 the errors of which are between 0:00 and 0°25 ot! MUN a TENA Re ea io eG Slatted “St, AL ee ene ee OR LE Ree, CHE ig Rn 2 Vi ia eae ‘ha elaine | a Po keel IE, me AE PE ges SRE EUS A TOY PRG O es tga Pere! Te ee ee tat Heo TRAY Ome PACITY A, gl Papitonh crete Sipe. 5? Cee nated AUMie TnL Nene at (eg s SR, ee RID, TH tea ety There is, therefore, only 1 division out of nearly 26, where the deviation from regularity amounts to 1 second and up- wards. This extraordinary accuracy in a circle of 18 inches radius appears hardly credible, and I avail myself of this op- Vol. 63. No. 313. May 1824. Yy portunity 354 M. Bessel’s Examination of the Division portunity to express the admiration which this high perfec- tion has forced from me. If the probable irregularity of a diameter determined by six divisions resulting from this con- tingent error, = +0133 *, which may be somewhat in- creased by the errors of my own operations, be compared with the above determined errors of division, there is, on the one hand, no doubt that there is some regularity in them; on the other hand, the irregularities which occur in them are no longer surprising. But if any advantage is to be derived from their investigation for the reduction of the observations, the irregular errors of division must be separated from the re- gular ones; for the latter only can be taken into account as the circle is read off by verniers, which in almost every ob~- servation coincide with different divisions of the circle. In this respect there is an essential difference between the circles with microscopes, and those with verniers: by ap- plying my method one may entirely do away in the for- mer the effects of the errors of division; the latter are always affected by the irregular part of the errors of division (as it is not well practicable to examine every single division), and allow only the attainment of a certain degree of precision, the more accurate determination of which is of consequence for the valuation of the final result. On the other hand, the ver- niers have the advantage oyer the microscopes by their perfect invariability, and their giving more accurate results when the observations depend on divisions which have not been ex- amined: with the microscopes the same contingent errors al- ways occur; with the verniers they change almost every day. IT have endeavoured to separate the irregular errors of divi- sion from the regular ones, and to determine the latter in such a manner as to allow them to be taken into account. I have best succeeded in this by considering the parts of the circle as abscissee, and the errors as above found as ordinates; and by drawing freely with the hand, a curve agreeing with them as nearly as was consistent with continuity, having before in- creased the 48 errors of division above given, by means of some more bisections, which, however, deserve less confidence. I am far from believing that the ordinates of the curve will correctly represent the law of the errors of division; but I be- lieve myself to be warranted in assuming that the application of the curve will lead nearer to the truth, than if it were neg- lected. Supposing the curve to be correct, the errors of those divisions should be taken from it, which coincide with the divisions of the vernicr; but if on account of the possible 4 OB251 6 ~ = 01327,—Transt.] errors of Reichenbach’s Circle ai Konigsberg. - 355 errors of the verniers, and for the sake of convenience, we suppose that the coincidence always takes place in the middle of the vernier, or 2° 15’ from their zero point, the errors arising from this supposition will be less than the errors of the curve itself. On this supposition the curve gives for com- plete observations read off by four verniers, the following cor- rections : ; . | Errors}, Errors Readings of the Circle. of Readings of the Circle. of Division.: 1 Division. D ° ‘| ° 1 ° 1 5) 87 45.177 45/267 45 0} 91 30181 30271 30 5| 95 15.185 15)275 15 0} 99 0189 0279 0 9) 50 15140 15/230 15,326 15, +0-27 54 0144 0/234 0/324 +019 57 45)147 45)237 45,327 45] 40-01 61 30151 30.241 30/331 30,—0-03 65 15155 15/245 15)335 15; 40-02 159 0.249 0/339 0'+0-08 162 45.252 45)342 45} 40-12 76 30166 30256 30/346 30; 40:15 80 15/170 15)260 15)350 15!40-16 84 0)174 0/264 0/354 0,401 87 45177 45/267 45)357 45, 0-00 27 45/117 45.207 45297 45 31 30/121 30.211 30,301 30 35 15,125 15,215 15)305 15 39 0129 0219 0309 0 42 45/132 312 LVIII. On Mr. Baspace’s new Machine for calculating and printing Mathematical and Astronomical Tables. From Francis Baity, Esq. F.R.S. & L.S.* HIS invention of Mr. Babbage’s is one of the most curious and important in modern times; whether we regard the ingenuity and skill displayed in the arrangement of the parts, or the great utility and importance of the results. Its proba- ble effect on those particular branches of science which it is most adapted to promote, can only be compared with those rapid improvements in the arts which have followed the intro- duction of the steam-engine; and which are too notorious to be here mentioned. * The object which Mr. Babbage has in view, in constructing his machine, is the formation and printing of mathematical tables of all kinds, totally free from error in each individual copy: and, from what I have seen of the mechanism of the instrument, I have not the least doubt that his efforts will be crowned with success. It would be impossible to give you a correct idea of the form and arrangement of this machine, or * From M. Schumacher’s Astronomische Nachrichten, No, 46. Yy2 of 356 Mr. F. Baily on Mr. Babbage’s new Machine for calculating of its mode of operation, without the help of various plates, and a more minute description than is consistent with the na- ture of your journal. But, it will be sufficient to say that it is extremely simple in its construction, and performs all its operations with the assistance of a very trifling mechanical power. Its plan may be divided into two parts, the mechani- cal and the mathematical. The mechanical part has already been attained by the actual construction of a machine of this kind: a machine for com- puting numbers with two orders of differences only, but which I have seen perform all that it was intended to do, not only with perfect accuracy, but also with much greater expedition than I could myself perform the same operations with the pen. From the simplicity of the mechanism employed, the same principles may be applied in forming a much larger ma- chine for, computing tables depending on any order of dif- ferences, without any probability of failure from the multitude of wheels employed. ‘The liberality of our Government (always disposed to encourage works of true science and real merit) has induced and enabled Mr. Babbage to construct a machine of this kind, capable of computing numbers with four orders of differences; and which will shortly be completed. . ‘To this machine will be attached an apparatus that shall receive, on a soft substance, the impression of the figures computed by the machine: which may be-afterwards stereotyped or sub- jected to some other process, in order to ensure thei per- manency. By this means, each individual impression will be perfect. The mathematical part depends on the method of differences to which I have above alluded: a principle well known to be, at once, simple and correct in its nature, and of very exten- sive use in the formation of tables, from the almost unlimited variety of its applications. It has been already successfully applied in the computation of the large tables of logarithms in France ; and is equally applicable in the construction not only of astronomical tables of every kind, but likewise of most of the mathematical tables now in use. But, the full and complete application of this, and indeed of every other principle in the formation of tables, has been hitherto very much impeded by the impossibility of confining the attention of the computers to the dull and-tedious repeti- tion of many thousand consecutive additions and subtractions, or other adequate numerical operations. The substitution, however, of the unvarying action of machinery for this laborious yet uncertain operation of the mind, confers an extent of prac- tical power and utility on the method of differences, unrivalled by and printing Mathematical and Astronomical Tables. 357 by any thing which it has hitherto produced: and which will in various ways tend to the promotion of science. The great object of all tables is to save time and labour, and to prevent the occurrence of error in various computations. The best proof of their utility and convenience is the immense variety that has been produced since the origin of printing; and the diversity of those which are annually issuing from the press. The general tables, formed for the purpose of assisting us in our computations, may be divided into two classes: 1°. those consisting of natural numbers: 2°. those consisting of loga- rithms. Of the former kind are the tables of the products and powers of numbers, of the reciprocals of numbers, of the na- tural sines, cosines, &c.&c. Of the latter kind are not only the usual logarithmic tables, whose utility and importance are so well known and duly appreciated, but also various other tables for facilitating the several calculations which are constantly required in mathematical and physical investigations. I shall allude to each of these in their order. 1°. Tables of the products of numbers. The numerous tables of this species which have been published at various times and in different countries, sufficiently attest their utility and importance: and there can be no doubt that, if their ac- curacy were undeniable, their employment would be much more frequent. One of the first tables of this class was pub- lished in ** Dodson’s Calculator ;” and contains a table of the first nine multiples of all numbers from 1 to 1000. In 1775 this table was much extended, and printed in an octavo size: it comprehended the first pine multiples of all numbers from 1 to 10,000. Notwithstanding these and other tables of the same kind, the Board of Longitude considered that still more extended tables might be useiul to science, and employed the late Dr. Hutton to form a multiplication table of all numbers from 1 to 1000, multiplied by all numbers less than 100. These were printed by their directions; and it is to be pre- sumed that no expense was spared to render them accurate : yet in one page only of those tables (page 20) no less than forty errors occur, not one of which is noticed in the printed list of the errata. The French Government, likewise,sensible of the utility of such tables, ordered the construction of a still more extensive set for the use of several of its departments. These are comprised in one volume quarto, and extend from the multiplication of 1 by 1 to 500 by 500: and in the year 1812, they caused a second edition of those tables to be printed. But, the most convenient tables of this kind which have yet appeared were recently published at Berlin, by M. sar anc 358 Mr. F. Baily on Mr. Babbage’s new Machine for calculating and comprise, in one octavo volume, double the quantity of the French tables. Another volume, of the same size, which is announced by the same author, will render these by far the most valuable of their kind, provided their accuracy can be relied on. ‘The quantity of mental labour saved, in the con- struction of such tables, by the help of the machine, is literally infinite: for, in fact, no previous calculation is at all requisite; and it will be necessary merely to put into the machine, at the end of every two pages, the number whose multiples are re- quired. ‘This number will be successively 1, 2,3, &c. ... to 500. 2°. Tables of Square Numbers. ‘The squares. of all num-. bers, as far as 1000, were a long time ago published on the. continent by M. Lambert. These have been since extended as far as the square of 10,000 by Mr. Barlow of the Royal Military Academy at Woolwich. The Board of Longitude’ employed the late Dr. Hutton to calculate a similar table as far as the square of 25,400. In computing a table of this kind by the machine, even if extended to the most remote point that could be desired, the whole of the mental labour would be saved: and when the numbers 1, 1, 2 are once placed in it, it will continue to produce all the square numbers in suc- cession without interruption. This is, in fact, one of those tables which the engine already made is capable of computing, as far as its limited number of wheels wiil admit. 3°. Tables of Cube. Numbers. ‘lables of this kind have likewise been already computed by Mr. Lambert and Mr. Barlow ; and also by the late Dr. Hutton, by order of the Board of Longitude. In computing such a table by the ma- chine, the whole of the mental labour would be in this case also saved: since it would be merely necessary to place in the machine the numbers 1, 7, 6, 6; and it would then produce in succession all the cube numbers. 4°, Tables of the higher Powers of Numbers. The Board of Longitude employed Dr. Hutton also to construct a limited table of this kind; which should contain the first ten powers of all numbers from 1 to100. And Mr. Barlow has published, in his collection, a table of the fourth and fifth powers of num- bers between 100 and 1000. Should it be thought desirable to re-compute or extend these tables, the whole labour may be performed by the help of the machine, except the few figures required to be first placed in it; and which might per- haps occupy the computer about ten minutes for each power.’ In fact, the computation of these few fundamental figures would uot occupy so much time, nor be so liable to error, as the cal- culation of one of the tabular numbers, according to the usual method, 5°, Tables and printing Mathematical and Astronomical Tables. 259 5°. Tables of the Square Roots and Cube Roots of Num- bers. A table of the first kind has been given by Mr. Lam- bert: and a more extended one by Mr. Barlow, in his Col- lection. The latter writer constructed his table by means of differences; an advantage which may be applied with greater effect to the table of Cube Roots, on account of the greater convergency of this order of differences. 6°. ‘Tables of the Reciprocals of Numbers. These are amongst the most simple but most useful of arithmetical tables ; and are peculiarly valuable in converting various series into numbers, —thus facilitating the calculation of differences for the more ready construction of other tables. In order, however, to be employed in such operations, it is absolutely necessary that they should be infallible. Several tables of this kind have been printed : the most recent and extensive of which are those of Mr. Barlow and Mr. Goodwin. 7°. Tables of Natural Sines, Cosines, Tangents, &c. The utility of tables of this kind is evident from the variety of forms in which they have been, from time to time, printed: and it is needless to insist on their importance at the present day, since no seaman dare venture out of sight of land with- out a knowledge of their use. In order to be of any real ser- vice, however, they should be accurate; and diligently revised from time to time: otherwise they may be worse than useless. The labour of computing tables of this kind will vary accord- ing to the number of figures contained in the result. It ap- pears desirable that the larger tables of this sort should be printed with their several orders of differences to a much greater extent than formerly, for the purpose of making other tables, and for executing several mathematical operations be- neficial to science. It would be difficult to state precisely the quantity of mental labour saved by the machine, in construct- ing tables of the kind; but, I believe, it may be fairly reduced to the two thousandth part of the whole. 8°. Tables of the Logarithms of Numbers. Tables of this kind are in the hands of every person engaged in nume- rical investigations: and it is needless to dwell on their utility and importance. The logarithms of number from | to 108,000 have been already computed, with a greater or less number of figures; but this has been the work of various authors, and of several successive years: the labour is so im- mense that no human being has ventured to undertake the whole. The tables which now exist are chiefly copies from those original and partial computations. By the help of the machine, however, this immense labour vanishes, and new tables may be readily computed and re-computed as often as may 360 Mr. I. Baily on Mr. Babbage’s new Machine,for calculating may be required by the public. It is probable that the pre- sent tables, if extended from 108,000 to 1,000,000 would be of greater utility than an extension of the present tables to a Jarger number of figures. The quantity of mental labour saved by the machine may be estimated in the following man- ner. Suppose a machine constructed, capable of computing with five orders of differences; it would be necessary to cal- culate those differences for every thousandth logarithm only: consequently, if the table extended from 10,000 to 10,0000, there would be but ninety sets of differences to compute. Any one of these sets being placed in the machine, with its first five differences, it will deliver the 500 preceding loga- rithms and also the 500 succeeding ones; thus producing a thousand logarithms: at the end of which term, another set of differences must be substituted. With five orders of diffe- rences, a table of logarithms may be computed to eight places of figures, which shall be true to the last figures, and it would not require more than half an hour to compute each set of differences; particularly as the higher numbers require very little labour, two or three terms of the series being quite suffi- cient. 9°. Tables of Logarithmic Sines, Cosines, Tangents and Cotangents. The remarks which have been made in the pre- ceding article, will apply with nearly equal propriety to the tables here alluded to. The mental labour required for their construction by the machine is reduced to a very insignificant quantity, when compared with the prodigious labour employed in the usual way. 10°. Tables of Hyperbolic Logarithms. - Some small tables of this kind have been printed in several works, and are useful in various integrations; but the most comprehensive set was computed by Mr. Barlow, which contains the hyperbolic lo- garithms of all numbers from 1 to 10,000. The labour of computing them is very great, which is the cause of their not being more extended. From a slight examination of the sub- ject, it would appear that the mental labour may, in this case; be reduced by the machine to about a two hundredth part of what was formerly necessary. 11°. Tables for finding the Logarithms of the sum or dif ference of two quantities, each of whose logarithms is given. This table, which was first suggested by Mr. Gauss, has been printed in at least three different forms. It is extremely con- venient when many similar operations are required: the whole of it was computed by the method of differences; and con sequently nearly the whole of the labour may be saved by the help of the machine. 12°, Other and printing Mathematical and Astronomical Tables. 361 - 12°. Other general tables might also be here mentioned, which have been of great service in various mathematical in- vestigations, and have been computed and printed by different authors: such as tables of the powers of :01, ‘02, -03, &c.: tables of the squares of the natural sines, cosines, tangents, &c.: tables of figurate numbers, and of polygonal numbers : tables of the length of circular ares: tables for determining the irreducible case of cubic equations: tables of hyperbolic functions, viz. hyperbolic sines, cosines, &c., and logarithmic hyperbolic sines, cosines, &c. These and various other tables which it is needless here to mention, may be computed by the machine, with very little mental labour, and with the greatest accuracy. Besides the general tables above alluded to, there are many others which are applicable to particular subjects only: the most important of which are those connected with astronomy and navigation.— When we contemplate the ease and expedi- tion with which the seaman determines the position of his vessel, and with what confidence he directs it to the most di- stant quarter of the globe, we are not perhaps aware of the immense variety of tables which have been formed almost solely for his use: and without the aid of which he dare not venture on the boundless ocean. Not only must the general tables of the sun and moon be first computed, together with the various equations for determining their apparent. places; but those places also for every day in the year are prepared solely for his use; and even for different hours in the same day. The places of certain stars must likewise be given: and, as these depend on precession, aberration and nutation, tables of this kind also must be formed for each star. Then come the lunar distances, which are computed for every third hour in the day; and which depend likewise on a variety of other com- plicated tables. After these come the Requisite Tables, pub- lished by order of the Board of Longitude, and the usual Loga- rithmic ‘Tables for facilitating the computations, both of which are dependent on other tables from which they have been de- duced or copied. Now, when it is considered that an error, in any one of these multifarious tables, will affect the last re- sult, and thereby render the navigator liable to be led into difficulties, if not danger, it must be acknowleged that it is of very essential importance that all such tables should be com- puted and printed in so perfect a manner that they may in all cases be depended upon. This however, in the present mode of constructing them, is scarcely possible. I have myself dis- covered above five hundred errors in the work containing the Tables of the Sun and Moon, from which (till lately) the an- Vol, 63. No. 313. May 1824, Liz nual 562 Mr. F. Baily on Mr. Babbage’s new Machine for calculating nual volumes of the Nautical Almanac have been computed : and a respectable author has asserted that, in the first edition of the Requisite Tables, published by order of the Board of Longitude, there were above a thousand errors. Many of the subsidiary tables, above alluded to, have not been computed since they were first printed: for, the mental and even manual labour of calculating them has been so great that the world has been obliged to remain contented with those original com- putations: and they are consequently subject to all the errors arising from subsequent editions and copies. In the calculation of astronomical tables, the machine will be of very material assistance: not only because an immense variety of subsidiary tables are required to determine the place of the sun, moon and planets, and even of the fixed stars, but likewise on account of the frequent change which it is found necessary to introduce in the elements from which those tables are deduced: and which vary from time to time according to the improvements in physical astronomy and the progress of discovery. y bata Within the last twenty years it has been found necessary to revise almost all the tables connected with the solar system: and already many of these have been found inefficient for the refined purposes of modern astronomy. But the great ex- pense of time and Jabour and money has been the principal obstacle-to the advancement of this part of the science: since each revision has been attended with the introduction of new equations, which consequently require new tables, And, to this day, we have not been furnished with any tables what- ever of three (out of the four) new planets that have been dis- covered since the commencement of the present century: nor can the places of many thousands of the fixed stars be readily determined for want of the subsidiary tables necessary for that purpose. It perhaps may be proper to state that a// astronomical tables (with very few trifling exceptions) are deduced by the two following methods: 1°. by the addition of certain con- stant quantities, whereby the mean motions of the body are determined; 2°. by certain corrections (of those motions) which depend on the sine or cosine of a given arc; and which are called equations of the mean motions. ‘The mean motions of any of the celestial bodies may be computed by means of the machine, without any previous calculation: and those quan- tities depending on the sine and cosine may in all cases be computed by the machine with the help of two previous cal- culations of no great length or labour, and in most cases with the help of one only. . . In and printing Mathematical and Astronomical Tables. 368 In the year 1804 Baron de Zach published his Tables of. the Sun: and within two years of that date, Mr. Delambre published similar tables. In 1810 Mr. Carlini published his ‘Tables of the Sun, on a new construction: so that within the space of six years it was considered necessary by these distin- guished astronomers to publish these three interesting and highly useful works. In the year 1806 Mr. Burg published his very valuable tables of the moon; a work which superseded the use of Mason’s tables, and was rewarded with a double prize by the French Government. It was received with gratitude by the scientific in every nation, and opened a new era in the his- tory of astronomy and navigation. These were followed by the tables of Burckhardt in 1812; which are still more accu- rate than those of Biirg: and at the present moment, the ele- ments of some new tables have been deduced by Mr. Da- moiseau. But it is the elements only which have yet been deduced: since it is these alone which can be expected to en- sage the attention of the profound mathematician. Never- theless the laborious, yet useful, operation of computation cannot safely be left to inferior hands. The merit of each is however very unequally estimated by the world. Euler had three hundred pounds granted him by the English Govern- ment for furnishing the elements, and Mayer three thou- sand for the actual computation of the tables of the moon, which were published by the Board of Longitude in the year 1770. The elements of Mr. Damoiseau have been already two years before the public: but the time and labour necessary to compute the tables therefrom are so great that they have not yet appeared. In order to deduce the place of the moon from these elements, no less than 116 different equations are requisite, all depending on the sine or cosine of different ares. The labour of computing each equation, with the pen, would be immense; and liable to innumerable errors: but, with the assistance of the machine, they are all deduced with equal fa~ cility and safety, and without much previous computation. - In the year 1808 Mr. Bouvard published his tables of Jupi- ter and Saturn: but in 1821, owing to the progress of dis- covery and the advancement of physical astronomy, 1t was found necessary to revise the elements ; and an entire new set of tables was then published by this distinguished astronomer. In order to deduce the geocentric places of these planets, it is requisite to compute no less than 116 tables depending on the sine or cosine of certain arcs. I shall not intrude further on the time of your readers by Z22 alluding 364 Mr. F. Baily on Mr. Babbage’s new Machine for calculating alluding to the tables of the other planets, which are ail liable to similar observations: but I shall take the liberty of calling their attention to those very useful tables which have from time to time appeared for determining the apparent places of the fixed stars; and which generally assume the title of “© Tables of Aberration and Nutation.” Tables of this kind are of vast importance to the practical astronomer, since they save a great deal of time and labour in the reduction of obser- vations: and it is believed that many valuable observations re- main unreduced, for want of convenient tables. of this sort. The first general tables of this kind were published by Mr. Mezger at Mannheim in 1778, and contained, the cor- rections of 352 stars. In 1807 Mr. Cagnoli extended these tables to the corrections of 501 stars: and in the same year Baron de Zach published at Gotha his Tabule speciales Aber- rationis et Nutationis, which contained the corrections for 494 zodiacal stars. But, already these tables have nearly outlived their utility. Independent of their very limited extent, the elements Senin which they were deduced, have been super- seded by others more agreeable to actual observation; which together with their exclusion of the solar nutation, and other minute quantities which cannot safely be neglected in the pre- sent state of astronomy, renders these tables of doubtful utility to the practical astronomer. The number of zodiacal stars (without including the very mi- nute ones) is considerably above a thousand: each of which may, in the course of a revolution of the nodes, suffer an occultation by the moon. These occultations are ascertained to be visible at sea, even from the unsteady deck of a vessel under sail: and afford the surest means of determining the longitude, provided the position of the star could be well ascertained. In order to furnish the corrections for each star, ten equations are re- quisite, depending on the sine and cosine of given arcs; so that it would require the computation of upwards of ten thou- sand subsidiary tables in order to produce the necessary cor- rections ; a labour so gigantic as to preclude all hope of seeing it accomplished by the pen. By the help of the machine, however, the manual labour vanishes, and the mental labour is reduced to a very insignificant quantity. . For, as I have already stated, astronomical tables of every kind are reducible to the same general mode of computation; viz.,by the con- tinual addition of certain constant quantities, whereby the mean motions of the body may be determined ad injinitum ; and by the numerical computation of certain circular functions for the correction of the same. The quantities depending on these circular functions, let them arise from whatever source they and printing Mathematical and Astronomical Tables. 365 they may, or let them be dependent on any given law what- ever, are deducible with equal ease, expedition and accuracy by the help of the machine. So that, in fact, there is no limit to the application of it, in the computation of astronomical tables of every kind. I might now direct your attention to those other subjects of a particular nature, to which the machine is applicable; such as tables of Interest, Annuities, &c. &c.: all of which are re- ducible to the same general principles, and will be found to be capable of being computed by the machine with equal fa- cility and safety. But, 1 trust that enough has been said to show the utility and importance of the invention; an invention inferior to none of the present day; and which, when fol- lowed up by the construction of a machine of larger dimen- sions now in progress (by which alone its powers and merit can be duly appreciated), will tend considerably to the ad- vancement of science, and add to the reputation of its distin- guished inventor. I have omitted to state that this machine computes, in all cases, to the nearest figure, whatever it may be. That is, after the required number of figures are computed, if the next following figure should be a 5 or upwards, the last figure is increased by unity, without any attention on the part of the operator. But, it is not in these mechanical contrivances alone, that the beauty and utility of the machine consist. Mr. Babbage, who stands deservedly high in the mathematical world, con- siders these but of a secondary kind, and has met with many curious and interesting results, which may ultimately lead to the advancement of the science. The machine which he is at present constructing will tabulate the equation A‘w,=c: con- sequently there must be a means of representing the given constant c, and also the four arbitrary ones introduced in the integration. There are five axes in the machine, in each of which one of these may be placed. It is evident that the ar- bitrary constant must be given numerically, although the num- bers may be any whatever. The multiplication is not like that of all other machines with which I am acquainted, viz. a repeated addition—but is an actual multiplication: and the multiplier as well as the multiplicand may be decimal. A machine possessing five axes (similar to the one now con- structing) would tabulate, according to the peculiar arrange- ment, any of the following equations : Diu, = Az +1 Aku, = AU, +2 Avu,+, = au, + Atu, Aduge1 = CA%Uz4+1 + Ay If 366 Mr. F. Baily on Mr. Babbage’s new Machine. If the machine possessed only three axes, the following series, amongst others, might be tabulated, Arn +) = ahu, + Au, Aju, = au,. If there were but two axes, we might tabulate Aru, = AUz +1 These equations appear to be restricted; and so they cer- tainly are. But, since they can be computed and printed by machinery, of no very great complication, and since it is not necessary (after setting the machine at the beginning) to do any thing more than turn the handle of the instrument, it be- comes a matter of some consequence to reduce the mode ef calculating our tables to such forms as those above alluded to. A table of logarithms may be computed by the equation A‘u, = c: but in this case the intervals must not be greater than a few hundred terms. Now, it may be possible to find some equation, similar to those above mentioned, which shall represent a much more extensive portion of such tables, — possibly many thousand terms: and the importance that would result from such an equation renders it worthy the attention of mathematicians in general. A table of sines may, for a small portion of its course, be represented by the equation A*u, = c: but it may be repre- sented in its whole extent by the equation A?u,= au, +1. Now, this is precisely one of the equations above quoted : and if a proper machine were made (and it need not be a large one) it would tabulate the expression A sin § from one end of the quadrant to the other, at any interval (whether minutes or seconds) by only once setting it. It would not be very com- plicated to place three such machines by the side of each other, and cause them to transfer their results to a common axis, with which the printing apparatus might be connected. Such a machine would, amongst other tables, compute one from the expression A sin 6 + B sin 26 + C sin 36 the utility of which, in astronomy, is well known. In fact, Mr. Babbage is of opinion that it would not be impossible to form a machine which should tabulate almost any individual equation of differences. Amongst the singular and curious powers produced by small additions to the machinery, may be reckoned the possi- bility of tabulating series expressed by the following equations : A‘u, = the units figure of u,, A’u, = 2x the figures found in the tens place of , 41, Au, = 4x the figures found in the units and tens place of Unity and many others similar thereto. Again : Prof. Hare’s Electro-magnetic Experiments. 367 S } Again: Let the machine be in the act of tabulating any series, a part may be attached by means of which, whenever any particular figure (a 6 for example) occurs in the units place, any other number (23 for instance) shall be added to that and all the succeeding terms: and when, in consequence of this, another figure 6 occurs in the units place, then 23 more will be added to that and all the succeeding terms. Or, if it be preferred, the number added shall be added to the term ending in 6 only, and not to all succeeding ones. These views may appear to some persons more curious than useful. They lead however to speculations of a very singular and difficult nature in determining the laws which such series follow: and they are uot altogether so remote from utility as may be Ace ae I avoid alluding to many other curious properties which this machine is capable of exhibiting, as they will scarcely be intelligible till the machine itself is more known in the world. Indeed I fear I have already tired your pa- tience with this long letter. LIX. A brief Account of some Electro-magnetic and Galvanic Experiments. By Roserr Hare, M.D. Professor of Che- mistry in the University of Pennsylvania.* Sen hundred feet of copper wire, nearly as thick as a — knitting-needle, were made to encircle the columns of the lecture room. One end of the wire was connected with one end of a large calorimotor; the other terminated in a cup of mercury—into this, a wire proceeding from the other pole of the calorimotor was introduced. Under these circumstances, a magnetic needle placed near the middle of the circuit, was powerfully affected; and when the circuit was first inter- rupted, and then re-established by removing the wire from the cup, and introducing it again, the influence appeared to reach the needle as quickly as if the circuit had not exceeded seven inches in extent. ‘The needle being allowed to become sta- tionary in the meridian, while the circuit was interrupted, and the end of the wire being then returned into the mercury, the deviation of the needle, and the contact of the wire with the metal, appeared perfectly simultaneous. A wire was made to circulate with great rapidity, by means of two wheels, about which it passed like aband. The wheels being metallic, and severally connected with the different poles of a calorimotor, it was found that the motion neither * Communicated by the Author. accelerated 368 Mr. J. Walsh on the Circle. accelerated nor retarded the galvanic influence—and it made no difference whether the needle was placed near the portion of the wire which moved from the positive pole to the nega- tive, or the portion which moved in the opposite direction. If a jet of mercury, in communication with one pole of a. very large calorimotor, is made to fall on the poles of a horse- shoe magnet communicating with the other, the metallic stream will be curved outwards or inwards, accordingly as one or the other side of the magnet may be exposed to the jet—or as the pole communicating with the mercury may be positive or negative. When the jet of mercury is made to fall just within the interstice, formed by a series of horse-shoe magnets mounted together in the usual way, the stream will be bent in the direction of the interstice, and inwards or out- wards, accordingly as the sides of the magnet, or the com- munication with the galvanic poles, may be exchanged. ‘This result is analogous to those obtained by Messrs. Barlow and Marsh* with wires or wheels. It is well known that a galvanic pair, which will, on immer- sion in an acid, intensely ignite a wire connecting the zinc and copper surfaces, will cease to do so after the acid has acted on the pair for some moments—and that ignition cannot be reproduced by the same apparatus, without a temporary re- moval from the exciting fluid. I have ascertained that this recovery of igniting power does not take place—if, during the removal from the acid, the galvanic surfaces be surrounded either by hydrogen gas, nitric oxide gas, or carbonic acid gas. "When surrounded by chlo- rine, or by oxygén gas, the surfaces regain their igniting power in nearly the same time as when exposed to the air. The magnetic needle is, nevertheless, much more powerfully affected by the galvanic circuit, when the plates have been allowed: repose, whether it take place in the air or in any of the gases above mentioned. I have not as yet had time, agreeably to my intention, to examine the effect of other gases, or of a vacuum. LX, On the Circle. By Joun Watsu, Esq. I N my last paper in your Journal +, I alluded to a proposition demonstrated by the binomial calculus. I shall state, in this paper, the nature of that demonstration. By the principles of the binomial calculus, the part of the tangent between y and 7 is the dinomial of ~, whatever may be dz, wu being * See Philosophical Magazine, vol. Ixii. p. 321. + p- 271, the Bangma’s Method of solving Equations. 869 the arc of any curve. Binomiating from this term, taking dx negative, and, in the binomiation, for dr substituting ., the sinomial or arc is equal to the sum of the remaining terms of the series. If, then, for x we substitute any constant in- volved in the equation of the curve, the sinomial will be de- termined in terms of this constant. Applying this to the cir- cle, we get for the length of the fourth part of the circum- ference the well known series ; : } 1.3 133.5 ee= 11+ iri dpe eter GD WNP UaES lade From which it follows, that the circumferences of circles ar to one another as their diameters. The preceding proposition does not appear to have been demonstrated before the invention of the binomial calculus. Euclid does not demonstrate it. His reasoning is founded on a lemma (the base of the method of exhaustions, of fluxions, of the differential calculus, &c.), which asserts the absurdity that a magnitude may be less than itself. And his attempt to prove this absurdity involves the assertion of the opposite absurdity, that a magnitude may be greater than itself. The second proposition of his twelfth book was deduced by analogy from the property of similar polygons; and he was obliged to _ heap absurdity on absurdity, to give his postulate the colour of demonstration. This is the only blemish in the most im- portant work on science that was ever composed, or that can hereafter be composed. Every other work on science, either physical or mathematical, falls into insignificance when com- pared with the stupendous work of this immortal geometer. _ With respect to Mr. Ivory’s paper. I require of Mr. Ivory to construct the triangle, of which the base is not any thing. He is not :to prove his construction by a simple appeal to ‘every body.” Such a mode of reasoning does not belong to geometry. Neither is he to introduce the “ ghosts of departed quantities.” or it is demonstrated that such things are ab- surd. He is to prove his construction by reasoning referred to our intuitive knowledge. His paper is a very awkward surrender of the point he would maintain, Cork, May 15, 1824. J. Watsu. LXI. On a Method of finding the Limits of the Roots of the higher Powers of Numerical Equations. By Mr. J. Rowsoruam. To the Editors of the Philosophical Magazine and Journal. Walworth, May 17, 1824, &} HOULD you think the following method of solving, or rather of finding the limits of the roots of the higher Vol. 63. No. 313. May 1824. 3A powers 370 Bangma’s Method of solving Equations. powers of numerical equations* (translated from O, S. Bang- ma’s Dutch Algebra) would be interesting to your readers, and worthy of insertion in your valuable publication, I shall feel happy in having communicated it to you. I am, gentlemen, respectfully yours, J. RowBorHam. To find the roots of the higher powers of equations, we shall begin with the following cubic equation: ; w—]4z2°—I9r= — 546. Bring all the terms of the equation to one side and arrange them according to the power of x, as follows: v—142°—29r + 546=0. ’ For x substitute three successive terms of a series of na- tural numbers; as, —1, 0, and 1, by which the following re- sults will be obtained : 560, 546, 504. By subtracting the first of these numbers from the second, and the second from the third, we have —14 and —42. Again: by subtracting the first number from the second, we have —28. The preceding numbers may be arranged as follows : —1]560_ 44 0 | 546_ 4-28 1 | 504 The lower numbers 1, 504, —42, —28, and the constant number 6, serve to find the positive roots of cubic equations, The upper numbers —1, 560, —14, —28, and the con- stant number 6, serve to find the negative roots +. To find the positive roots, write in a line, 1, 504, —42, —28. * This method of solving equations will be further illustrated (should we not be too limited for space) in A Practical System of Algebra, by Mr. Peter Nicholson and myself, which work is now in the press, and will be published in a short time. + The preceding method is applicable to all the higher powers, with this difference only,—that we must take for » so many successive terms of the series of natural numbers, as the highest exponent of 2 contains units ; thus, For cubic equations 0, 1,2; or —], 0, 1. For biquadratic 0,1, 2,3; or —], 0, 1,2. For 5th power 0, 1, 2,3,4; or —2, —1, 0, 1,2, &c. The constant nuniber, mentioned above, will be formed ; , For the 3d power, by 1x 2x3=6. For the 4th power, 1X2x3x4=24. For the 5th power, = 1xX2xK3x4x 5=120, &e. Now, Bangma’s Method of solving Equations. 371 Now, by adding the constant number 6 to —28, we have —22; by adding —22 to —42, we have —64; by adding —64 to 504, we have 440 which is the value of the function r}—142*—29x+ 546, when r=2; we then write in a line 2, 440, —64, —22. Now, by adding 6, and proceeding as above, we shall have 860 which is the value of the function, when x= 3, &c. The calculation may be arranged in the following manner: ae) ny ey =—64 US-+92 6 2, 440 --—64 —22 = 80. 0d —16 6 3, 360 —80 —16 =90 305-10 6 4, 270 —90 —10 — Oy: Ba bn A 6 5,176. ~-—94 —4 —92 2 6 6, 84 —92 2 —~84 8 6 ieee ea 8 Here 0 is the value of the equation, when a=7; conse- quently 7 is one of the roots. Now, in order to find the other positive roots, we must continue the calculation as follows, by which means we shall find that r=13 is also a root. 7, Oo |. aad, 8 —70 14 6 Rh eT gy 14 —50 20 6 5, — 100" 1 rad 20 —24. 26 6 lOpimlAh 724 26 8 32 6 i) eae ae 32 46 38 6 12, —90 46 33 90 44 6 13, 0... 90» 44 $AQ Note. 372 On the Application of the Term “ Infinite.” _Note. Whenever all the numbers that stand on a line with a value of 2 become positive, we may conclude that the equa- tion has no greater positive roots; therefore 13 is the greatest positive root in this equation. To find the negative roots, write the upper numbers in a line, and subtract the constant number 6. dyl PGReitac=N4yl) 1288 20. —34 6 —2, 540 20 —34 60 —40 6 —3, 480 60 —40 106 —46 6 =f, 374 Of -106 60.46 158 —52 6 —5, 216 158 —52 216. —58 6 —6, 0 216 —58 Note. Whenever all the numbers that stand on a line with a value of x become — +; ++ —, we may conclude that the equation has no greater negative roots; therefore x= —6 is the greatest negative root of the proposed equation. LXII. On the Application of the Term “ Infinite.” To the Editors of the Philosophical Magazine and Journal. Gentlemen, ] BEG to offer the following observations in reply to your note, appended to a proposition contained in the paper ‘© On the Origin of Matter, and on its alleged Infinite Divi- sibility,” which you were so obliging as to insert in the Philo- sophical Magazine for November last. I am, gentlemen, Yours respectfully, London, January 19, 1824. J.O.F. If space be considered as a property of a subject existing necessarily, and which therefore, as proved by Dr. S. Clarke, must be necessary to the existence of ‘all other things; such property thus existing necessarily, and not being a Peo. oO On the Application of the Term “ Infinite.” 37$ of any created subject, must in this case be regarded as an at- tribute of the Deity, of which infinity may of course be pre- dicated. If, however, space be considered—what I believe it to be —a property of matter; as in this case also it cannot exist independent of its subject, there can be no such thing in na- ture as absolute space or absolute vacuum. Under this view, then, if we take away matter, we take away space. Space may indeed be nevertheless abstractedly conceived of, or ima- _ gined, as existing independently of matter as its subject: but in reality it can have no such existence, and can only be con- sidered as a property co-existent with matter, as its subject. Now, universality cannot, I apprehend, be predicated of the material part of creation, without affirming that there are no other modes of substantial existence except what are pro- per to material being and substance ; I therefore conclude, that matter is not universal, and consequently not infinite ;—thus, that neither its qualities nor physical properties are infinite :— and that the material universe forms, as it were, but the out- work or lowest basis of created existence, between which and the Creator there are intermediate modes of existence; al- though no direct physical proof, perhaps, can be given of modes of existence different in their nature from those of mat- ter and space. The reality of such superior modes of ex- istence may however be presumed from the nature of the human mind, which as it were can look into the things of space, although in itself it is not subject to or limited by space; but has a mental perception or consciousness of an existence according to a superior mode; and, if I may be allowed the expression, within the sphere of outward space and nature. _ If it be true that space is proper to material nature alone, and if there be other modes of existence which are not sub- ject to the laws that govern matter, then space cannot be universal,—thus cannot be infinite; and the same will apply to all physical properties whatever. f With respect to infinite duration: that which is necessarily existing must be considered as antecedent to that which is created :—thus all created things must be considered, as to duration of existence, to have begun to be; in this respect, therefore, their duration must be limited, and if limited, not infinite ;—although they may nevertheless continue to exist to eternity. Infinite duration therefore can only be applied to the self-essent, self-existent, and underived being of the Creator. Considering therefore that all created subjects, by the necessity of their constitution, are limited and finite, their qualities or properties in like manner must be sy ae nite ; 374 On the Nautical Almanac. finite; in which case the term infinite is strictly inapplicable to physical properties ; as well as to moral and intellectual pro» perties, except as these latter exist in the Creator. With respect to infinite series in mathematics: they may be made the measure of any thing real or unreal; they may be applied to aid our conceptions of the infinite attributes of God, or of the indefinite attributes of his works; but the appli- cation, to be genuine, must evidently be with due regard to the nature of the thing to which it is made, as observed in my: former remarks upon this subject. . It appears to me that that which is Infinite must be Universal, extending through all modes of being from the first to the last. LXIII. Two Lines from the Nautical Almanac, addressed to Mr. Ivory. - [F we employed the height of the thermometer without, which would be more consistent with the theory, it would probably be ecessary to suppose the standard tempera~ ture of the table 48° only, instead of 50°.”—N.A. p. 148. For Mr. Groombridge’s observations, it is remarked, in the 13th Number of the Astronomical and Nautical Collection, that it will be necessary to alter the supposed standard of the tables to 46°, instead of 48°. Mr. Ivory, in the Philosophical Magazine for April, insists on employing the table of the Nautical Almanac at 50°; and on finding the sum of its errors +96"°7 and —13’-0. Now if he has computed rightly for 50°, these errors, sup-. posing the temperature 48°, become 56"°9 and 260; for 47°, + 363 and —35"°8; the sum of which is 72-1. This is indeed, a trifle more than the sum of the errors of the new table, which amounts to 60” only; but is still far short of 109°°7, or. rather 119”°7 the sum of the errors assigned to the N. A. by- Mr.Ivory. So inconsiderable a difference, in the neighbour- hood of the horizon, can scarcely be considered as decisive of the question, even allowing the accuracy of the computation : and it has not been asserted that the New Tables are inferior. to those of the N. A. But the comparison which Mr. Ivory considers as tricked out in all sorts of disguises for the purpose of ensnaring unwary judges, does in fact prove that both of these tables give the correction for accidental changes of temperature somewhat too great; they are both founded nearly upon the same hy- pothesis respecting the effect of a change of temperature, and that hypothesis is not fully justified by Mr. Groombridge’s observations. S.B.L. , LXIV. No- [ w8PS. J LXIV. Notices respecting New Books. Recently published. PRINCIPLES of Warming and Siig Public Build- ings, Dwelling-houses, Manufactories, Hospitals, Hot- houses, Conservatories, &c-; and of constructing Fire-places, Boilers, Steam-apparatus, Grates, and Drying-rooms: with Illustrations experimental, scientific, and practical. To which are added, Observations on the Nature of Heat; and various Tables useful in the Application of Heat. With nine Plates and several Wood Cuts. By Thomas Tredgold, Civil En- gineer; Member of the Institution of Civil Engineers; Author of « Elementary Principles of Carpentry,” an “ Essay on Cast Iron,” &c. &c. 15s. The Character of the Russians, and a detailed History of Moscow. Illustrated with numerous Engravings. With a Dissertation on the Russian Language; and an Appendix, containing Tables, political, statistical, and historical; an Ac- count of the Imperial Agricultural Society of Moscow; a Catalogue of Plants found in and near Moscow; an Essa on the Origin and Progress of Architecture in Russia, &c. &c. By Robert Lyall, M.D. F.L.S., Member of the Imperial So- cieties of Agriculture and Natural History, and of the Physico- Medical Society at Moscow. An Essay on the Laws of Gravity, and the Distances of the Planets; with Observations on the Tides, the F igure of the Earth, and the Precession of the Equinoxes. By Captain Forman, Royal Navy. 4s. Evils of Quarantine Laws, and Non-existence of Pestilen- tial Contagion; deduced from the Phenomena of the Plague of the Levant, the Yellow Fever of Spain, and the Cholera Morbus of Asia. By Charles Maclean, M.D. The Metropolitan Literary Journal, No. I. An Elementary System of Physiology : by J. Bostock, M.D. F.R.S. L.S..M.R.I.A. &e. &c. ANALYSIS OF PERIODICAL WORKS ON NATURAL HISTORY. The Zoological Journal, No. 1., conducted by Messrs. T. Bell, J, G. Children, J. D. C. Sowerby, and G. B. Sowerby. The hope we expressed on announcing the intended publi- cation of this work, of its materially promoting the advance- ment of zoology, has not been disappointed by the perusal of it. We think that, with the improvements always received by a periodical publication during its progress, it will become j a standard 376 Notices *especting New Books. a standard medium of communication between the various cultivators of that-delightful science. This first number con- tains fifteen articles, principally original ; besides the usual de- partments of literary and scientific intelligence found ina Phi- losophical Journal. Among them we may particularize the fol- lowing: —Art. I. An Inquiry into the true Nature of Instinct, and of the Mental Distinction betwscen Brute Animals and Man, &c.: by J. O. French, Esq. In this inquiry the author pro- poses to account for the various actions of brutes which ap- pear to be of a moral or of a scientific nature, by the hypo- thesis that moral and scientific qualities do not become ob- jective in the minds of brutes, thus that they possess no moral or scientific consciousness; and therefore that the appearances of morality and science in their actions, are the effects of moral and scientific energies, acting upon them in a region of their minds above the sphere of their proper consciousness. —Art. II. Monograph on the Cebrionide, a Family of Insects. By W.E. Leach, M.D. F.R. & L.S.—Art. VI. Some Odser- vations on the Lamarckian Naiades, and the Propriety of uniting them all under one generic Name. By G. B. Sowerby, F.L.S. Mr. Sowerby proposes to unite the genera Alasmodonta_ of Say, Dipsas of Leach, Anodon, Hyria, and Castalia of La- marck, with some other shells, under the genus Unio ; repre- senting that they have been separated from it merely upon such characters as would warrant the raising of almost every strongly marked species into a genus.—Art. XI. Monograph on the Cypreide, a Family of Testaceous Mollusca. By Mr. J. E. Gray.— Art. XIV. Abstract of a Memoir on the Physio- logy of the Helix pomatia. By M. B. Gaspard, D.M.: with Notes by T. Bell, Esq. F.L.S. This is a curious memoir on the growth, habits, and physiology of the H. pomatia. Mr. Bell’s notes correct M. Gaspard’s statements on several im- portant points.x—Art. XV. Memoir on the chemical Composi- tion of the corneous Parts of Insects. By M. Augustus Odier. With some Remarks and Experiments by J. G. Children, Esq. F.R. & L.S. M. Odier affirms in his memoir, that the sub- stance resembling horn, obtained by treating the elytra of in- sects with a hot solution of potash, and which he calls chitine, contains no nitrogen; and he compares it to lignin. Mr. Children, however, has determined, by analysing it with prot- oxide of copper, that chitine does contain a considerable pro- portion of that element; thus invalidating M. Odier’s in- ference respecting the analogy of the substance to the basis of vegetables. —The Number contains five plates, four of which, principally of Shells, are well coloured.—The Second Number is to be published on the 15th of June. ; Curtis's Analysis of Periodical Works on Natural History. $77 Curtis’s British Entomology. No. 5. contains the following subjects : Pl. 19. Rhipiphorus paradoxus. Figures of both sexes of this insect are given, which from their dissimilarity have been considered by some authors as distinct. Mr. W. S. MacLeay, we believe, first discovered its singular economy, which has énabled entomologists to enrich their cabinets with examples of this rare and curious genus.—PI. 20. Pentatoma caerulea, a beautiful little species found in the woods about London, and in Devonshire ; the author has taken the opportunity of giving a complete arrangement of the British species which the genus embraces.—PIl. 21. Eyprepia rus- sula (Clouded buff Moth). A genus detached from the extensive group of Bombycide ; E. russwa is a beautiful species, and the dissections illustrat- ing the Lepidoptera must be a great acquisition to the lovers of that beau- tiful order, as nothing of this kind has hitherto appeared excepting the few that were given in the early numbers of Mr. Swainson’s Zoological Ilustrations.—PI. 22. Ibalia Cultellator. An unique specimen of this insect, which adds a new genus tu the British Fauna, was taken by Mr. Edwards at Bungay, and is now in the cabinet of the author. It is allied to the Gall insects (Diplolepide), and its structure is yery interesting. The Botanical Magazine. No. 448. Pl. 2481. Urtica involucrata, “ caule ramoso hirsuto, foliis oppositis ro- tundato-ovatis crenatis trinerviis lucidis ad apices ramorum congestis, pani- culis sessilibus :” brought from the island of St. Vincent, and flowered in the stove of the Horticultural Society.—Serratula simplex, the Carduus mollis of older authors. —Oxytropis pilosa, Astragalus Linn. This plant and the former were introduced at the Chelsea garden by Dr. Fischer of Petersburg.— Nicotiana repanda from the Havannah, said to be the plant of which the famous cigars are made. — Habranthus versicolor, a se- cond species of this genus of Amaryllidee proposed by Mr. Herbert (see - 297). —Dalea mutabilis.— Justicia geniculata, “paniculis terminalibus foci cernuis, bracteis subulatis, foliis ovato-lanceolatis glabris subtus pal- lidis distantibus:” native of the West Indies. —Cissus antarctica, New South Wales. The Botanical Register. No.111. Pl. 793. Portulaca foliosa. “ P. guineensis, foliis subulatis, calycibus_pi- losis, involucro polyphyllo, floribus subternis, petalis retusis.” Lindley MSS.— Neottia bicolor, “ foliis plurimis lanceolatis nervosis petiolatis gla- bris, scapo villoso infra foliolis spathaceis obsito brevioribus; racemo nu- meroso floribus cernuis, labello oblongo, lamina summa brevi oblata obso- leté trifida undulata crenata, intis minuté papillosa:” from Trinidad.— Eriospermum folioliferum : originally figured in Andrews’s Repository: as well as its congener FE. paradoxicum, it ranks among the most curious ano- malies with respect to foliage in the Monocotyledones.—Justicia pectoralis: now first figured, though long known here. —Justicia carthaginensis, in- troduced in 1792 from the Caribbee islands.— Lantana fucata, “ foliis ovatis rugosis crenatis obtusis pubescentibus petiolum brevem decurrentibus, ca- pituli parvi depressi pedunculo foliis breviori:” raised from seeds brought for the Horticultural Society from Brazil by Mr. G. Don.— Glycine vincen- tina.— Prunus paniculata, Vol. 63. No. 313. May 1824. 3B LXV. Pro- 2 wiBZ8\ Vibe LXV. Proccedings of Learned Societies. ROYAL SOCIETY. : April 29. A LETTER was read, from Dr. T. L. Tiarks to Dr. Young, For. Sec. R.S., as Secretary to the Board of Longitude; relating to observations made on the longitude of various places in England in 1822 and 1823 *. May 6.—The reading was commenced of a paper “ On Univalves;” by C. Collier, Esq. Staff Surgeon. Communi- cated by Sir James MacGregor, F.R.S. May 13.—The reading of Mr. Collier’s paper was con- cluded; and Davies Gilbert, Esq. V.P. R.S., communicated a paper * On the Variation of the Rates of Chronometers with the Density of the Atmosphere ;” by George Harvey, F.R.S.E.+ May 20.—A letter was read from Professor Berzelius, of Stockholm, to the President; givng an account of various chemical researches in which he has recently been engaged. He has succeeded in obtaining Silicon, or the combustible base of silica, in an insulated state; and has ascertained its principal properties, which are very curious. The reading was also commenced of a paper * On some new Pheenomena effected by Magnetic Influence ;” by Mr. J. H. Abrahams, of Sheffield. Communicated by Mr. Tooke, F.R.S. LINNHAN SOCIETY. May 4.—A. B. Lambert, Esq. V. P. in the Chair. M. Geoffroy St. Hilaire was elected a Foreign Member. A notice from Mr. Wood was read respecting the Golden Oriole, Oriolus Galbula, shot on the 26th of April, flying in company with some blackbirds, at Aldershot in Hampshire. The reading was continued of Mr. Vigors’s paper on the Natural Affinities of Birds; and of the Catalogue of Norfolk and Suffolk Birds, by the Rev. Messrs. Sheppard and Whit- tear. May 24.—On this day, being the birth-day of Linneus, the Anniversary of the Society was held at one o’clock, in conformity with the Charter, the Right Rev. the Lord Bishop of Carlisle, Vice President, in the Chair. The following gentlemen were re-elected Officers : Sir James Edward Smith, President; Edward Forster, Esq. Treasurer ; Alexander MacLeay, Esq. Secretary ; Mr. Richard Taylor, Assistant Secretary. * See Phil. Mag. vol. Ixiii. p. 66. + See our last Number, p. 311: The Linnean Society.— Horticultural Society. $79 The following were elected to be of the Council for the en- suing year :— Edward Barnard, Esq.; H.'1. Colebrooke, Esq. ; Major-General T. Hardwicke; Daniel Moore, Esq.; and Philip B. Webb, Esq. An extensive and interesting series of the various species of Rhubarb from Chelsea Garden was exhibited by Mr. An- derson. The Anniversary dinner of the Society took place at Free- masons’ Tavern, and a considerable number of the Fellows, including many from distant parts of the kingdom, partici- pated in the pleasure of this meeting, which was alloyed only by the absence, owing to indisposition, of their highly esteemed President, whose excellent qualities, great attainments, and invaluable labours for the promotion of science, have long endeared him to those who know him, and especially to the lovers of Natural History. The chair was filled on this occasion by the venerable Prelate, who from the first foun- dation of the Society has been one of its most zealous sup- porters, ——. HORTICULTURAL SOCIETY. May 1.—At the Anniversary Meeting for the election of the Council and Officers for the ensuing year, the following Gentlemen were chosen :—Council : Thomas Andrew Knight, Esq.; the Earl of Aberdeen; Edward Barnard, Esq. ; Mr. Samuel Brookes; Henry Moreton Dyer, Esq.; John Elliot, Esq. ; Alexander Henderson, M.D.; Charles Holford, Esq. ; Robert Henry Jenkinson, Esq.; Mr. Joseph Kirke; Mr. George Loddiges; Alexander MacLeay, Esq.; Joseph Sa- bine, Esq.; Richard Anthony Salisbury, Esq. ; John Wal- ker, Esq.—Officers: Thomas Andrew Knight, Esq. President; John Elliot, Esq. Treasurer; Joseph Sabine, Esq. Secretary ; Mr. John Turner, Assistant Secretary. The President appointed the following Members of the Council Vice Presidents for the ensuing year :—the Karl of Aberdeen; John Elliot, Esq.; Robert Henry J enkinson, Esq.; John Walker, Esq. May 4.—The following communications were read : Note on the Culture of the Canna indica, By Dr. Van Mons, a Foreign Member of the Society. Note on Gratting the Rose. By the same. — On the best Mode of packing Grafts for Carriage. By the same. : On the Cultivation of Asparagus. By Mr. Peter Linde- r, a Corresponding Member of the Society, Gardener to he King of Denmark. ~ ; Several new plants in flower, raised in the Society’s Garden , 3B2 from 380 Geological Society. from seeds received from Chili, were exhibited; also a re- markably large and fine plant, in flower, of Cactus speciosus from the garden of the Comte de Vandes. May 18. The following communication was read : Note on the Advantages of using Bunting as a Protection to Apricot Trees. By Charles Henry Rich, Esq. F.H.S. GEOLOGICAL SOCIETY. March 19.—A paper entitled “ Sketch of the Ceolney of New South Wales and Van Dieman’s Land,” by the Rev. T. H. Scott, was read in part. April 2.—The paper entitled “ Sketch of the Geology of New South Wales and Van. Dieman’s Land,” by the Rev. T. H. Scott, was concluded. : The coast. of New Holland from Cape Howe to Port Stephens, including Botany Bay, Port Jackson, &c., as ex- amined by Mr. Scott, consists of an uninterrupted series of the coal measures. At Illasvarro, or the Five Islands, a seam of coal is found at the surface. Between Broken Bay and Port Hunter, a horizontal seam of coal is bared by the action of the sea on the cliffs. Very good coal is worked at New- castle on Hunter’s river, thirty-seven yards from the surface, 3 feet 1 inch thick; it is intersected by trap dykes in some places; and vegetable remains of a large-leaved fern, thought by the people to be an Eucalyptus, are picked up at the base of the cliff Limestone alternates with the sandstone, and iron ore occurs. ‘The wells at Sidney being not more than 30 feet deep, the water is not good; one well, sunk 82 feet to a great mass of sandstone, gives excellent water. From Paramatta the coal measures continue, and are broken by trap dykes at the Nepean to Enuford, where the ascent of the Blue Mountains commences, near the summit of which the coal measures rest on the old red sandstone. The escarpment of this rock on the east side presents the aspect of a perpen- dicular wall, at the top of which the old red sandstone is found in contact with primitive rocks: these occur in the vale of Cleuyd and Clareneer’s hilly range, where the Macquarrie rises, and after a north-east course of 300 miles terminates in a vast swamp. Returning westward, porphyritic rocks and clay slate accompany the primitive rocks near Bathurst and the Sidmouth range, to Lake George and the Cookbun- doon river, which continue to the Cow pastures, where the coal measures of the colony again appear. The geology of the island of Van Dieman’s Land is con- formable to = ade of the continent of New Holland. Both Hobart Town and George Town are upon the coal formation. Between Geological Society. 381 Between the former and Elizabeth Town, a limestone full of shells is found, probably of the oolite series, and the same rock occurs near George Town on an island in the Tamar. In the middle of the island, at Bagdad, a rock which answers to the description of the millstone grit, and salt, is found on the river Macquarrie. To the east and the west of the in- habited tract between the two towns, high mountains and ele- vated primitive ridges are alone discoverable ; so that the island probably contains little other fertile soil to tempt future emi- gration when this space shall have been peopled, which is not the case in New South Wales. A letter was read On a Section obtained in sinking a Well at Streatham; by Mr. I. S. Yeats. Communicated by G. H. Brown, Esq. A well having been sunk at Streatham to the depth of 285 feet, the greatest depth which has been pierced in that part of the country, the following section was exhibited. From the depth of 2 feet to 29 feet, stiff reddish brown clay; from thence to 35 feet, clays with septaria; from thence to the depth of 180 feet, blue clay, in which, in from 70 to 100 feet, were found various shells and fragments of bituminous wood with iron pyrites ; from 200 feet to the depth of 230 feet, blue clay, sometimes sandy, in which numerous shells and bitu- minous wood occurred; at 230 feet, round black pebbles of flint like those of Blackheath were found, this appearing to be the point of junction between the London and plastic clays ; next a bed_of sand, and afterwards various coloured clays were pierced, at the depth of 270 feet; and continuing to 285 feet, sand and sandy clays occur, the greater part of which is full of green earth exactly resembling that of the oyster bed at Reading. The paper was accompanied by spe- cimens of each of these strata. A letter was read from Alexander Gordon, Esq., to D. Gor- don, Esq. of Abergeldie, describing three successive forests of fir imbedded in a peat moss, accompanied by specimens. The moss of Auldguissack in. Aberdeenshire, Scotland, presents an inclined plane of rather uneven surface, and va- ries in depth from 18 inches to 10 feet from the lower part of the hill to the river. Upon digging up the ground in two different parts of the moss, large roots of Scotch fir-trees were found about one foot below the ordinary average level of the moss. Below the bottoms of these roots there is a stratum of about a foot and a half of moss, below which other roots or trunks ap- peared ; and on digging still further down (about 6 or 7 feet below the ordinary level of the moss) a third set of roots and truncated stems of trees were discovered, It 382 Astronomical Society. It appeared to Mr. Gordon impossible that these roots could have supported different trees all growing at the same , time; for the distinct ramifications of these (horizontally like Scotch firs at the present day) are bedded in moss perpendi- cular above each other. April 23.—A paper was read entitled ‘‘ Some Observations on the Lakes of Canada, their Shores, Communications,” &c. by Lieut. Portlock, R.E. In this memoir the author describes the various nature of the shores of Lakes Huron, Michigan, Erie, and the other lakes of Canada, and annexes a plan, in which a tabular view is presented of the comparative level of these lakes and their communications with each other. At the Falls of Niagara, he observes that the upper stratum isa firm compact limestone rest- ing on strata of a very schistose nature. It is not by erosion of . the surface that the falls are made to recede; but the waters, after falling 150 feet, strike the bottom, and are reduced to foam ; they are then driven up into the air far above the rock whence they had descended: this penetrating foam acts on the lower argillaceous strata, till the overhanging rock is un- dermined. Lieut. Portlock remarks, that there has been a gradual fall in the level of the Lakes at Canada. He also offers some considerations on the proximity of the sources of several rivers which flow in opposite directions. May 7.—A paper ‘“ On the Geology of the Ponza Islands, in the Mediterranean,” by G. P. Scrope, Esq. M.G.S., was read in part. A letter was read from Thomas Botfield, Esq., M.G.S., accompanied by a collection of bones and horns of the deer, and bones of man and other animals, found in a cleft of the rock at a quarry at Hincks’ bay, (near the Old Park iron works, ) in the parish of Dawley and county of Salop. Their adhesion when applied to the tongue showed that the animal gelatine was nearly gone, which does not take place till after a long perio: of inhumation. ASTRONOMICAL SOCIETY. May 14.—The whole of this sitting of the Society was occupied by the reading of the conclusion of Mr. Baily’s paper On the Method of determining the Difference of Me- ridians, by the Culmination of the Moin, this paper having been commenced at the last meeting in April. The author, after briefly alluding to the nautical methods of determining the longitude, including those by means of chro- nometers, adverted to five distinct astronomical methods which have been pursued, viz. Ist, By the eclipses of Jupi- ter’s satellites. Qdly, By eclipses of the moon. 3dly, By eclipses Meteorological Society. 383 eclipses of the sun. 4thly, By occultations of the fixed stars. And 5thly, By meridionial transits of the moon. ‘The first three of these, by reason of their infrequency and obvious sources of inaccuracy, are of very limited utility ; while the fourth method is rendered uncertain from its involving a doubtful datum, the compression of the earth, as well as other difficulties which the author pointed out. He then proceeded to point out that the fifth method was greatly superior to any of the others, in which opinion he was supported by the tes- timony of Dr. Maskelyne, Bernoulli, and many eminent astronomers who were quoted. Notwithstanding its high re- commendations, this method has not been successfully adopted in practice, and has even led to some awkward anomalies, on account of its having been customary to take the moon’s centre reduced to the meridian, and to compare it with the apparent places of stars passing the meridian about the same time in any parallel of declination. The newly proposed method consists in merely observing with a transit instrument, the differences of right ascension between the border of the moon, and certain fixed stars pre- viously agreed upon, restricting the observations to such stars as differ very little in declination from the moon, and denomi- nated moon culminating stars. The attention of astronomers has been called to this method by M. Nicolai, of Manheim, in several numbers of Schumacher’s Nachrichten. It is quite independent of the errors of the Lunar Tables (except so far as the moon’s horary motion in AX is concerned). It does not involve the quantity of the earth’s compression. It does not require a correct knowledge of the position of the star ob- served, nor does an error of a few seconds in the clock sen- sibly affect the result. Hence much trouble is avoided, many causes of error precluded; besides all which, the method is universal. METEOROLOGICAL SOCIETY. March 10.—The reading of Dr. T. Forster’s Memoir on the Variations of the Reflective, Refractive, and Dispersive Powers of the Atmosphere” was resumed and concluded. This memoir relates to certain branches of the subject of atmospheric refraction, belonging to the province of Meteoro- logy, which Dr. Forster states to have been particularly neg- lected: these are, the variations in the refractive, dispersive, and reflective powers of the atmosphere, resulting from the diffusion therein of different modifications of cloud, which are themselves affected by local circumstances, and which vary greatly at different times; and the effects of that varia- tion on the colour of the light transmitted by the ee dee xec 384 Meteorological Society. fixed stars, and on the declination of the latter. After some general remarks on reflection, refraction, and prismatic di- spersion, the author proceeds to consider the subjects just mentioned, in three sections. In the first, * On the variation in the refractive power of the atmosphere at different times of the night and day, and on different occasions and seasons,” he ascribes that variation, principally, to the quantity and nature of the aqueous vapour diffused in the air: and he sup- ports this opinion by various obseryations on the planets and stars, made at different times and seasons. In observing the planets and brightest stars through prismatic glasses, he found that the spectrum was less oblongated, whilst the red colour was more distinctly apparent, at the period of the vapour point, than at almost any other time of the same nights. On other occasions, at the same period of evening, the violet and in general the colours of the most refrangible rays were most conspicuous, and the spectrum was more oblongated than or- dinarily. Dr. Forster at length ascertained, that the greater prevalence of the red in the spectrum uniformly accompanied that state of the atmosphere when the c7rrostratus diffused itself after sunset ; whilst the more oblongated spectrum, with the violet and most retrangible colours, attended an atmo- sphere in which the condensing vapours assumed the form of siratus. He infers from these and other observations, that the changes in the qualities of the diffused vapour in the air must produce great variation in the atmospherical refraction. In the second section of his memoir, he suggests that local cir- cumstances may produce great variation in the mean refrac- tive power of the atmosphere at different places; and that the discordances in the places assigned to the fixed stars in different catalogues of them, may have resulted from such variation. In the third section entitled ‘ Of varieties in the composition and nature of the light of different stars, considered as still further varying the effects of atmospheric refraction, reflection, and dispersion,” Dr. Forster details a number of minute observations upon those varieties ; pro- ceeds to inquire into their causes; and concludes with an ac- count of some experiments on the decomposition of the light of the moon, the planets, and certain fixed stars.* A Memoir by Dr. Forster was also read, .** On the great Depression of Temperature which occurred in January 1820.” The remarkable depression of temperature related in this * Part of Dr. Forster’s paper was inserted in the Phil. Mag. for March ; and the remainder will be found in the present number: both with consi- derable additions by the author. paper Meteorological Sociely. 385. pepet took place at Hartfield in Sussex, to the neighbour- ood of which place it appeared to be confined, during the period between sun-set on January 14th and midnight on January 15th, 1820. At 10 P. M. on the 14th, an out-door Fahrenheit’s thermometer exposed to the N. E. was at zero, and at 11 o’clock it indicated —5°. Some time between the hours of 1 and 8 A.M. on the 15th, it sunk to —10°, as shown by a Six’s thermometer. It thence gradually rose, until at midnight on the 15th it attained the elevation of +23. A thermometer exposed to the N. W. indicated 1° higher in each observation. During this period of excessive cold, the air was calm and clear, a few ill-defined cumuli only were seen on the 15th; the snow which had fallen on the 13th lay on the ground. Dr. Forster received only one notice of a distant observation, made at Canterbury, where a‘thermo- meter in-doors indicated 0°; which was also the temperature in-doors at Hartfield on the morning of the 15th. Dr. W. Burney communicated, through the Secretary, the Results of a Meteorological Journal for February 1824, kept at his Observatory at Gosport, Hants. April 14.—A note was read on certain Phenomena of the late Cold Weather, and on Zodiacal Light, &c. ; by Luke How-. ard, Esq. F.R.S. and Member of the Meteorological Society. Dr. Burney communicated the Results of his Meteorological Journal for March ; and similar communications were received from other Meteorologists. May 12.—Dr. Burney communicated the Results of his Journal for April; and the following paper was read : «* An Account of the principal Phenomena of Igneous Me- teors which were observed in the year 1823; forming part of a Review of theProgress of Meteorological Science during that period: with Remarks on the Characters of certain Meteorites.” By E. W. Brayley jun, A.L.S. and M. Met. Soc. In this paper the author first describes, from various authorities, the Fire-balls which were observed respectively on the 26th of January 1823, at Gosport; on the 23d of May, at Kiel in Denmark ; and on the 20th of August, at Ragusa. The lat- ter, being contemporaneous with an earthquake at the same place, gives occasion for an inquiry how far the appearance of Igneous Meteors may be considered as an attendant phae- nomenon of earthquakes: several meteors of this kind, it is observed, were seen in the province of Cutch at the time of the extensive earthquake in India in 1819, the most violent motion of which was experienced in that province and its vicinity ; and two Fire-balls appeared, one at Zante, and the other at Cer phalonia, on the day after the earthquake that desolated the Vol. 65. No. 313, May 1824. 3C former 386 Imperial Society of Naturalists of Moscow. former island in 1820: other instances of this connexion are. likewise adduced. Mr. Brayley then proceeds to an exami- nation of the phenomena attending the fall of several me-- teorites at Nobleborough, in the State of Maine, in North America, on the 7th of August last. He next points out a remarkable affinity in mineralogical characters subsisting be- tween these meteorites, and those which fell, respectively, at Loutolox in Finland in 1822, at Jonzac in France in 1819, and at Juvenas in the same country in 1821; several specimens of the latter being laid before the Society for the purpose of il- lustration. This affinity partly consists in the strong resem- blance which they all bear to certain products of volcanoes ; whilst the meteorites of several other descents connect them, by a gradual transition, with those whose characters are more, peculiar: from these and other circumstances, in conjunction with that of the frequent presence of Olivine in meteorites, the author infers that the agencies which give rise to volcanic: phzenomena, whatever these may be, and however exerted in this case, are probably concerned in the production of Igneous Meteors and the bodies which descend from them. He con- cludes by recommending the investigation of this curious sub- ject to the members of the Society; promising to lay before them, after the recess, the results of some further researches upon it. The Society then adjourned, over the Summer recess, to, meet again on Wednesday the 13th of October next. . —_ IMPERIAL SOCIETY OF NATURALISTS OF MOSCOW™%. “The plan for forming a depét for the discoveries in natu- ral history in the vast empire of Russia; of uniting the friends of this science together, who wished to give their assistance for this purpose; and of publishing the history of the discoveries made, was conceived by professor Fischer on his arrival at St. Petersburg in 1804. It was not till the summer of the the year 1805, however, that a few of the professors and ‘li- terati of Moscow first assembled, and adopted the regulations proposed by professor Fischer, and established the Jmpertat Society of Naturalists. ‘The object of the society is to en- courage the study of natural history and the relative sciences, as human and comparative anatomy, chemistry, natural philo= sophy, rural economy, &c. The society consists of members * The accounts of this Society, and of the Agricultural Society of Moss cow, are derived from the interesting History of Moscow lately published by Dr. Lyall... ordinary inperial Society of Naturalists of Moscow. 387 ordinary and honorary; and the ordinary members are di- vided into resident and non-resident. ‘Shortly after the association just mentioned took place, Mr. Muravief, curator of the university of Moscow, and col- league of the minister of public instruction, informed that the society had begun to meet at the house of the director, pro- fessor Fischer, presented its regulations to his imperial ma- jesty, the Emperor Alexander, who approved of the design, and therefore ordered Mr. Muravief to testify his high satis- faction to the professor. His excellency Count Alexei Ra- zumofskii, lately minister of public instruction, senator, che- valier, &c., was first chosen president. The present president is prince Obolenskii. The perpetual director, Gotthelf Fischer, Aulic counsellor of H.I. M., chevalier, doctor and professor, and member of many learned societies ; and vice-president of the medico-chirurgical academy. ‘Soon after the institution of the society, the literati, and particularly the cultivators of natural history, whose works are too little known in England, including many of the no- bility of Moscow, Petersburg, and the other towns as well as universities in Russia; and also many of the most distin- guished philosophers and naturalists on the continent, chiefly through the extensive acquaintance of the founder and direc- tor, professor Fischer, were enrolled among its members. Presents were received from all quarters, of books, objects of natural history, and of money. ‘The society was very flou- fishing, and by the year 1812 had published four volumes of its Transactions. All the collections of the society were de- posited in the museum of the university, and, along with that extensive establishment, became a common prey to the flames ‘in the year 1812. Among other things were lost some manu- scripts, and almost the whole of the impression of their Trans- actions, which, however, will be soon reprinted. «Far from being dispirited by this irreparable misfortune, the members of the society re-assembled in the year 1813, and commenced their proceedings anew ; and since have continued all their efforts with unremitting vigour to re- cover from their losses, and have now published the fifth yolume of their Transactions. The society has renovated a small museum and library. Among the foreigners, pro- fessor Fischer and Dr. Fischer, director of the botanic gar- dens at Gorengi*, are distinguished for their zealous ser- vices in this society. rom the change in the state of Eu- rope, -a more free interchange of scientific publications is .* The Philo-Graphic Scciety of Gorengi was instituted by Dr. Fischer, and alterwards was united with the Imperial Natural History Society. $C? to 388 Imperial Agricultural Society of Moscow. to be wished, and may be expected, between Russia and the Continent, as well as Great Britain. The director, professor ' Fiseher, is a most indefatigable naturalist, and although not more than fifty years of age, the catalogue of his works and translations on different subjects occupies nearly three quarto pages; and they better proclaim his character and the extent of his erudition than any encomium I can add. A few distin- guished characters of Great Britain are honorary ; but a greater number non-resident ordinary members of this society. ‘The so- ciety of natural histery of Moscow is well known on the Conti- nent, and wishes to be better known in Great Britain by an ex- change of its Transactions for the Transactions of the literary societies of our island; as well as to receive donations in na- tural history, or of the works of its members, or of other in- dividuals disposed to assist its views.” ’ IMPERIAL AGRICULTURAL SOCIETY OF MOSCOW. « The regulations of this society were published in the Rus- sian language in the year 1820. They commence with a short historical account of its formation, which is followed by some general remarks on the pleasures and advantages of agricul- ture, and on its influence on a nation, in a moral,-a political, and a commercial point of view. After a sketch of the opinions of the ancients regarding agriculture, its present state in Ger- many, France, and England, as also in America, is noticed. It is then stated that in Russia this science as yet is almost in its infancy. As contributing to the advancement of agri- culture in this empire, the effects of the works of the Free Eco- nomical Society at Petersburg;—the utility of the universities in Russia (each of which has a chair for agriculture); and the observations of the Economical Society of Livonia, are al- luded to. “ The difficulty of leaving off old, and of adopting new plans, is remarked ;—and especially among the peasantry. “ To the tzers état,—the middling ranks of society, which, exist in most countries of Europe,—arts and sciences, agri- culture and commerce, chiefly owe their improvement and perfection. Butin Russia there are no properly corresponding classes of society. The advancement of the arts and sciences, and of agriculture, principally depends upon the government, the nobility, the literati, and societies. Commerce in a great measure is in the hands of the merchants; but a few of the , nobility are great speculators. * As things are at present, by far the greatest part of the. stewards upon noblemen’s estates are their own slayes, and are generally very corrupt in their morals. Some of ee ee richer woe mee Imperial Agricultural Society of Moscow. 389 richer nobles have free stewards, and most of them are great villains: a few, however, are reputed for their honesty and good conduct*, «The Steward-Slaves, as they may be called, derive their knowledge of agriculture from the peasants; so that the di- rector and the servant are often equally wise: indeed it does not rarely occur that the latter is more learned in his pro- fession than the former. To procure a good and honest and clever steward in Russia, is a matter of infinite difficulty : hence an adage, ‘ Buy not a village, but buy a steward for yourself.” The present society seems to have it in view, as a principal object, to form stewards at the practical school, for their estates, ** An assembly of a number of highly respectable noblemen agreed to form an Agricultural Society at Moscow in the year 1818. A correspondence took place with the Government on this subject; and His Imperial Majesty Alexander granted leave to institute a society under the name of The Imperial Agri- cultural Society of Moscow. It was permitted that this society should have its own seal with the Imperial arms, and a suit- able device, and free postage of all letters and parcels. «The Emperor made a donation of 10,000 roubles to the society; and gave the promise of an annual sum when its utility was-evident :—he also presented the estate of 7 olmat- chevoi-Gorbovo, containing 70 desiatins of land, to the society. + “The design of the society is the improvement of agricul- ture, and of the management of cattle, as well as of the con- struction of farm-houses, &c. * Its members are divided into active members—who reside in or near town, and are supposed to be actively employed in some manner or other for the good of the society: to this class also belong correspondents, residing in the more distant provinces, * «Vide p. xxii. of the History. + “This estate is situated about JS versts (12 miles) from Moscow. His Imperial Majesty, it appears, was badly advised when he granted it to the Agricultural Society, In the first place, it was too small for the purposes of the Society; and in the second place, it was the most arid and unpro- ductive estate in the neighbourhood of the metropolis. The Society ac- cepted it ;—because it could not decline an imperial present: but imme- diately afterwards, it took a lease of another estate, called Butirka, situated about a mile from one of the Barriers (the Dmitrovskaya), which contains about 207 desiatins. Butirka is church property, but the Society intends to purchase it when rich enough. Part of this estate is now drained and cultivated, and a number of buildings are erected. Mr. Rogers, whose fa- ther has long been famcous in this neighbourhood as a practical farmer, is appointed its director, and always resides on the spot. The practical school spoken of in the text, is intended to be erected here. and 390 Imperial Agricultural Society of Moscow. and in foreign kingdoms :—and honorary members, whose conduct has merited general approbation, and who forward the objects of the society, as by presents of land or money ; or of individuals distinguished in the sciences, and’ especially in agriculture. “‘ The society is governed by a President, a Vice-President, a Director, a Secretary, and a Treasurer ; all of whose duties are particularly indicated. The meetings of the society are held once a month, from the 1st of November to the 1st of May. “The active members are formed into four divisions: 1. The Theoretical.—2. The Practical.—3. The Mechanica].—And, 4. The Pedagogical. The Ist division is to occupy itself with classical works necessary for the schools, and the transla- tion of agricultural papers and works from foreign languages. It consists of Professors and learned individuals. The 2d divi- sion contains landed proprietors in the government of Mos- cow, who ought to present to the society annual reports of the results of their practice in farming, and of improvements, ob- servations, &c. The 3d division is to engage itself with the most improved implements of husbandry used in Kurope— Agricultural architecture, as of farms, of mills, of stoves for drying corn, &c. This division is to consist of engineers and mechanics. ‘The 4th division will direct the operations of the theoretical and practical schools. A council consists of the head of each of these four divisions, the President, the Vice-Pre- sident, the Director, the Secretary, and the ‘Treasurer. * Asricultural School.—A proper site for the erection of a school, and for the formation of a garden, is to be fixed upon. Here there must be six fields, each containing four desiatins of land, for the purposes of the school. 'The school is to be supported by the sums annually received for the pupils, and also by their entry-money. There will be attached to it an over- seer and assistant; a surgeon, and two apprentices ; an under- officer for every eighty pupils; a clergyman; and _ teachers, Ist, for arithmetic, geometry, making of plans, mechanics, and agricultural architecture; Zdly, for botany and the theory of agriculture; $dly, for chemistry and technology ; 4thly, for veterinary surgery. “* Pupils.—The pupils are not to be under 15 years of age : they must know the Russian language previous to admission. If their conduct be bad, they may be sent from the school ; if they have passed six months in it, neither master nor friend can withdraw them until the conclusion of their education :— 2. e. at the end of five years. They are to be divided into tens, During the first year, they will be taught Russian gram- mar Imperial Agricultural Society ef Moscow. 391 mar and writing, arithmetic and painting. In the second year, theology, agricultural book-keeping, geography and statistics, and the principles of geometry. In the third year mechanics, agricultural architecture, and taking of plans. In the fourth year, chemistry, botany, physiology of vegetables, and know- ledge of woods or forests, and technology. In the fifth year,’ the sciences of agriculture and veterinary surgery. ‘Those de- siring it may remain longer than five years, on continuing a’ proper payment, and then they will be taught physics and law *. “‘ The annual sum to be paid for each pupil is: for food,. 100 roubles; clothes, shoes, and linen, 150r.: education and wood and candles, 150r.: total 400 roubles. And for fitting” out, entry, 100r. The money to be paid in advance. The Agricultural Society ‘s not rich. The crown has not yet been liberal, but it is expected that other donations will be made, both in land and money. A few of the opulent members have generously contributed. General Apraksin has given a small estate near Moscow, for the use of the Society, for twelve years. ‘The members ought to pay an annual sum of 50 roubles, but this is not enforced. Each member, ex- cept those specially exempted, pays 25 roubles for his diploma. Some of the members make an annual voluntary contribution. “ The Society has already published seven numbers of its journal in the Russian language. Hitherto it has been ac- tively employed, and has made a rapid advancement ; and I have no doubt, that if Prince Galitsin continue its president, and to reside at Moscow, even though he should resign the situation of Military Governor, it will go on in the same pro- sperous career. The Prince has contributed his share both in money and books. He offers an annual sum of 30 ducats ; Count Rumiantsof one of 35 ducats, and the Society a third of 35 ducats, for prize essays on subjects proposed by the Society. «The number of members in Russia is considerable. Many of the most respectable names of scientific individuals on the continent, and a number of those in Great Britain, are also - enrolled in its lists. «The plan of the Society has something in it grand and imposing :——May it lead to results extensive and useful to hu- manity !” * “This is of great consequence in Russia, should the nobles make stews ards of their pupils ; for the half of their duty may be to manage law pro- cesses, LV De f $920") LXVI. Intelligence and Miscellaneous Articles. NEW TABLES OF PRECESSION, ABERRATION AND NUTA=- TION. "THE Astronomical Society of London have undertaken the formation of an extensive work, which will prove highly useful and convenient to every practical astronomer. It is ‘the computation of Tables for determining the Precession, Aberration and Nutation of nearly 3000 of the principal fixed stars, for every day in the year; with their mean places for the beginning of the year 1830.. This list will contain all the stars, not less than the 5th magnitude, which are inserted in Piazzi’s catalogue; and also all the stars above the 7th mag- nitude, situated within 30° of the equator. ‘The tables will be constructed on the principles detailed in our Number for October 1822; and which has been partly acted upon on the continent by M. Schumacher. . This mode of arranging tables of this kind is by far the most convenient of any that has been hitherto adopted; as. by the help of 4 logarithms added to 4 other logarithms (all of which will be found-in the book) the correct quantities are determined without reference to any other work than a small table of logarithms to 5 places of figures. ‘The whole will be calculated by two computers, in order to guard as much as possible against errors. NAUTICAL MAGNETIC PREMIUM. The Board of Longitude have conferred the Parliamentary premium of 500/. on Mr. Peter Barlow, of the Royal Military Academy, for his method of correcting the local magnetic at- traction of ships. The great quantities of iron employed at this time in the construction and equipment of ships of war, produce so much deviation in the compass (varying according to the direction of the ship’s head) as to render it almost an useless instrument in certain situations, particularly in high northern and southern latitudes. It appears by Lieutenant Foster’s report of experiments made in His Majesty’s ship Conway, under the superintendence of Captain Basil Hall, to lat. 61 degrees S., and under that of Captain Clavering, in the recent voyage of the Griper, to lat. 80 degrees north, that the difference in the bearing of an object with the ship’s head at east and west, amounted to 28 degrees before the latter vessel left the Nore: this difference afterwards amounted to 50 de- grees at the North Cape, and to 75 degrees at Spitzbergen. Great, however, as this effect was, the method recommended by Mr, Barlow was completely successful in counteracting it, Steam-vessels.—Canals.— Meteor. 393 it. This is extremely simple: it consists in merely placing a small plate of iron-abaft the compass, in such a direction as to counteract in any one place the effects of the other iron in the ship: after which, without removing it, it continues to do the same in all parts of the world, whatever change may take place in the dip or intensity of the magnetic needle. Three important advantages will result from this discovery. It will add greatly to the safety of vessels in our Channel in dark and blowing weather: it wil] tend to the general correction of our charts of variation; and will dispel nine out of ten of the supposititious currents so liberally supplied by navigators to account for every remarkable disagreement between rec- koning and observation, and of which there can be no doubt the greater number have arisen from this long-neglected error in the compass. STEAM NAVIGATION TO INDIA. A numerous and respectable meeting has been held in Cal- cutta, for the purpose of taking into consideration the utility and possibility of establishing steam navigation with England via Suez. A committee had been previously formed, who hav- ing discussed the merit and importance of the project, opened a subscription, and recommended that the sum of one lack of rupees should be bestowed upon the first individual or com- pany who should make two complete voyages from England to India in steam vessels, the passage not to exceed 70 days, either by the Cape of Good Hope, or the Red Sea, in vessels of British register and of not less than 300 tons burthen. The recommendation of the Committee was adopted by the meet-- ing. STEAM VESSELS IN THE NETHERLANDS. The Dutch are actively employed in introducing the use of steam vessels into Holland; and one has just been established between Utrecht and Amsterdam, which performs the voyage every day in three hours and a half. CANALS FOR UNITING THE BLACK SEA TO THE BALTIC. A Company has just been formed, under the auspices of the Emperor, whose object is to unite the Black Sea to the Baltic by means of canals from the Dnieper and Nieman. METEOR. On the evening of Saturday the 17th of April, about a quarter past ten o’clock, a beautiful meteor was seen to the northward of the village of Upper Kinneil, parish of Borrow- stowness. It burst forth with great splendour, illuminating the atmosphere; and proceeded with amazing velocity in a Vol. 63. No. 313. May 1824. 3D S.E. 394 Earthquakes. S.E. or S.E. by S. direction, emitting a train of vivid sparks which gradually became paler until it entirely disappeared. Its duration, the writer of this, who witnessed the scene, thinks might be about five seconds, during which period it passed over about a third of the visible atmosphere. EARTHQUAKE FELT AT SEA. The following is from the log book of the ship Orpheus, bound from England to Ceylon : Monday, 10th February, 1823. “At lh. 15m. p.m. steering N.N.W. at the rate of five miles per hour, a little swell trom the S.S.E., felt a motion as if the ship was running over the ground, or some other solid sub- stance; and at the same time for from 60 to 65 seconds heard a confused grinding tremulous noise, affecting the ship in every part; we sounded with twenty fathoms of line up and down, but no ground. ‘The sea not the least confused, nor could we perceive the smallest appearance of any thing which could occasion this noise and motion. The ship was not felt to strike once: ske kept perfectly upright in her way through — the water, and answered the helm; nor did she make any wa- ter in consequence of the shock received. At 2h. 5m. P.M. another shock was experienced, but much lighter than the first; and about three p.m. a third, which was only just per- ceptible. The first was so violent as to unship one of the compass cards from its point in the binnacle; and a pair of boots, which were hanging on a nail driven into the mainmast between decks, were shaken off. The ship’s place at the first shock was 1. 10. N.; 84. 6. E.:—at the second, 1. 15. N.; 84.4. E.”-- Medical Repository. EARTHQUAKES. A pretty severe shock was felt in Trinidad on the morning of the 5th of January between three and four o’clock; but happily it did no damage. At Bergen in Norway, on the 6th of January, about half past five o’clock a.., a smart shock of an earthquake was ex- perienced, accompanied with a rumbling subterranean noise, by which the houses were so much shaken that the furniture was tumbled about. The direction was from S.W. to N.E. The noise continued nearly a minute; this shock was suc- ceeded soon after by another in the same direction, but weaker and. of shorter duration. Letters from St. Petersburg of the 7th of April announce, that in the night of the 11th of February a slight shock of an earthquake was felt at Irkutak in Siberia. Letters ; 1 { Remarkable Phaenomenon.—Statistics. 395 Letters received from the island of Santa Maura state, that on the 21st of February a violent shock of an earthquake was felt there about eight o’clock in the evening. It produced the greatest consternation in the minds of the people. Se- veral buildings were much injured, and the bridge which joins Fort Alexander to the city was broken down. No lives were lost, but two females were severely wounded. SINKING OF THE EARTH. Naples, April 5. Continual and excessive rains in the course of last month have caused a sinking in of the ground in the district of Avi- gliano, in the province of Basilicata, which has shaken a great part of the hill on which the town is built. This terrible heenomenon first manifested itself in the night of the 17th, by the fall of a house close to the barrack of the gendarmes. The house, which is totally destroyed, carried with it in its fall the barrack and several adjoining buildings. In the morning of the 23d, a greater misfortune followed; for a gulf opened near the inhabited parts, which swallowed up, under enormous masses of earth, two mills, of which not a vestige remains. The same day, all the young girls of the place were nearly the victims. They were going in procession to thechurch of St. Mary, about a mile from the place, to implore the Divine mercy in this moment of calamity, and they had hardly passed a certain spot, when the ground to the extent of five acres sunk in ‘witha tremendous crash, overthrowing all the trees that covered it, and destroying all traces of the road for about a quarter of a mile. At the same time another gulf opened on the north side. It may be supposed that many buildings in the town haye been damaged by this event. The Intendant of the province immediately sent an architect to save them from entire destruction. Happily no lives were - lost except one gendarme. On the same night there was a dreadful storm in the Adriatic. STATISTICS. Paris, May 21. It results from some tables just published by M. Benoiston, in a Mémoire sur les Enfans trouvés, that the number of foundlings has gone on increasing in every State in Europe, except from 1790 to 1800. During that interval the diminu- tion amounted to a third; but after that period, and particu- larly since 1815, the number has constantly increased. There were 51,000 foundlings in France in 1798, 69,000 in 1809, 84,500 in 1815, and 138,500 in 1822. According to the $D2 Annuaire 396 Education in Denmark.—South America. Annuaire du Bureau des Longitudes, there were in 1823, 932,130 births in the year, which gives one child abandoned out of every twenty-eight. It appears, from the information given by the Government, that the provinces near the sea, in which there are most populous cities, and which are the centre of arts and industry, containing 20,000,000 inhabitants, hardly give as many foundlings as the remaining 10,000,000 who oc- cupy the centre provinces, from which Paris and Lyons are subtracted, as each of them supplies 6000. EDUCATVION IN DENMARK. In Denmark the system of mutual instruction is making great progress; and although only a short time since it was established, there are already one hundred and forty schools where this method is followed. Count Moltke, Minister of State to the King of Denmark, is recently dead; and not content with patronizing the sciences during his life, he even wished to support them after his death. He has, in consequence, left to the University of Copenhagen 60,000 rix dollars, to be distributed as rewards to the Professors of Natural Sciences who shall treat certain questions to be pro- posed by the University in the best manner. He has also _ given 10,000 dalers to the Academy of the Fine Arts, and 100,000 to be employed in educating the sons of poor officers. These legacies are strongly contrasted with the regulations sometimes made in other countries in favour of monastic in- stitutions that some people are desirous of reviving. SOUTH AMERICA. M. Humboldt communicated to the Academy of Sciences, at its last sitting, some very interesting observations made by Messrs. Boussingault and Reveno, two travellers whom we have several times mentioned to our readers. These gentle- men have analysed an _ aérolite, weighing several guzntauz, which they found in the mountains of Santa Rosa, to the north-east of Santa-Ié-de-Bogota. They say, according to letters from Antioquia, that a mass of native gold has lately been found, weighing more than 190lbs. (They have proved the presence of both stilphuric and muriatic acids in the waters of a small river which runs from the volcano of Paracé, near Popayan, and which is called by the inhabit- ants Vinegar River. The letters of these gentlemen are up to January 5, 1824. At that time a School of Mines was about to be established at Bogota, and the country enjoyed the greatest tranquillity. —Constitutionnel. CANCER. Cancer.—Calendar of Flora, &c. 397 CANCER. The very remarkable number of cases of cancer in the neighbourhood of East Grinstead, Hartfield, and Withyham in Sussex, has attracted the notice of several medical persons, and it is likely that this subject will undergo some regular investigation as to its causes. Upwards of ten cases of direct cancer have died at the small village of Hartfield within four years. Some persons have attributed the prevalence of this disease to the waters, which, resembling those of Tunbridge Wells, are prodigiously unwholesome; while others lay it to the air. Mr. Wallis, surgeon, who in conjunction with Dr. Forster is making out a list of the cases, states that pork and hog’s flesh in general form the chief diet of the poor of the district ; and we have the concurrent testimony of several phy- sicians, that the flesh of the hog is very liable to bring on vio- lent diseases. Calendar of Flora, Fauna, and Pomona, at Hartfield in Sussex, Jor April. April 1.—The spring advances very slowly, and is at least a fortnight behind the usual time in most things. April 3.—Tulipa suaveolens in flower in the garden.— Hya- cinthus orientalis begins to blow.—Motacilla alba very abun- dant. April 5.—Cardamine pratensis in flower, though not com- mon yet. Its common name of Our Lady’s Smock evidently comes from its blowing about Old Lady Day. ‘This plant flowers very abundantly throughout April and May in this our moist country.— Pilewort begins now to be abundant, and to bespangle every shady bank with its yellow stars.— Erythronium dens canis in blow. April 6.—Certhia familiaris seen on the trees. April 8.—Fumaria officinalis flowers in the garden. April .10.—Narcissus incomparabilis in flower. April 15.—Sazifraga crassifolia begins to flower, which is a fortnight behind its mean time of flowering.—The Snake first seen to day. April 18.—Jynx Torquilla first seen at Hartfield.—Sylvia Pheenicurus seen. April 19.—Hirundo rustica first seen at Groombridge; this bird did not become common till quite the end of the month. April 20.—Tussilago petasites in flower.—Narcissi Tazette and N. orientales of various sorts in full blow in the gare, together with Hyacinthi orientales.—Borago officinalis flowers. April 22.—Cheiranthus Cheiri, Lamium purpureum, Leu- : cojum 398 Calendar of Flora, §c.—Obituary—Baron Maseres. cojum vernum, and the Claimond Tulip, which I call Tulipa precox, but which botanists have confounded with 7. Gesnerz, are now in blow.—This night the prodigious quantity of spiders on the walls of the house foretold the wet weather which fol- lowed. I have observed that this is as sure a sign of rain, as the much braying of the ass is of showery weather. April 24.— Cuculus canorus first heard.—Lilacs begin to throw forth leaves —The Cuckoo was heard at Walthamstow as early as April 21, its mean time at that place—Cowslip Primula veris now abundantly in flower in the meadows. Primroses still cover every bank, and mix agreeably with Violets. — Scilla nutans flowers here and there.—Narcissus bi-. color (vel N. petalis albis nectarium flavum subaequantibus) flowers in the garden. April 25.—Ranunculus Lulbosus begins to blow sparingly : during May this plant covers the meadows, succeeding the Dandelion now in profusion.—Stellaria holostea flowers plenti- fully. April 26.—The early Daffodil still abundantly in blow in a field near Fisher’s Gate in Withyam.— Narcissus tenuifolius in flower in the garden. April 28.—Erysimum Barbarea, E. Alliaria, Tulipa sylves- tris, Fritillaria Meleagris*, and FE’. imperiale, in flower at Hale End, Walthamstow. April 30.—Lychnis dioica in flower at Walthamstow. This has been in general a most unpropitious spring for flowers, and last winter although mild has killed a great variety of plants. April closed without having afforded one warm day. The Dandelion was still the prevalent plant that yellowed the meadows, mixed with Daisies. Harebells were as yet but few in number. Primroses and Polyanthuses abundant. A single Tulip appeared here and there in warm places.+ Hartwell, May 22, 1824. (pl Forster. Osituary.—Baron Maseres. On the 10th of May, at the advanced age of ninety-three, died Francis Maseres, Esq. F.R.S. Cursitor Baron of the Exchequer, a profound mathematician, a munificent patron of science, and an excellent man. * Fritillaria Meleagris was in flower plentifully May 10 in a mead be- tween Billington in Bedfordshire and the church at Slapton, Bucks,—a habitat of this plant not heretofore recorded, as we believe-—Enir. + On the 5th of May I found Narcissus biflorus in flower in abundance in a field near Lingfield; and as I saw other plants of the same species blowing in the marsh far remote from any house, I have no. doubt. of its being a genuine habitat. LIST List of New Patents. 399 LIST OF NEW PATENTS. To Alexander Dallas, of Northumberland-court, Southampton-buildings, in the parish of St. Andrew, Holborn, Middlesex, engineer, for his machine to pick and dress stones of various descriptions, particularly granite stone. —Dated 27th April 1824.—6 months allowed to enrol specification. To John Turner, of Birmingham, Warwickshire, brass- and iron-founder, for his machine for crimping, plaiting, and goffering linen, muslins, frills, and other articles. —27th April.—2 months. To George Vaughan, of Sheffield, Yorkshire, gentleman, for his improve- ment or improvements on steam-engines, by which means power will be gained, and expense saved.— lst May.—6 months. To John Crosby, of Cottage-lane, City Road, Middlesex, gentleman, for his improvement in the construction of lamps or lanterns for the better pro- tection of the light against the effects of wind or motion.—5th May.— 6 months. To James Viney, of Shanklin, Isle of Wight, Colonel in the Royal Artil- lery, for certain improvements in and additions to water-closets.—6th May. —6 months. To William Cleland, of Leadenhall-street, London, gentleman, for his improvement in the process of manufacturing sugar from cane juice, and in refining of sugar and other substances.—6th May.—6 months. To John Theodore Paul, of Geneva, but now residing at Charing Cross, Westminster, Middlesex, mechanist, who, in consequence of a communica- tion made to him by a certain foreigner residing abroad, is in possession of certain improvem2nts in the method or methods of generating steam, and in the application of it to various useful purposes.—13th May.—6 mo. To John Potter, of Smedley, near Manchester, Lancashire, spinner and manufacturer, for certain improvements in looms to be impelled by me- chanical power for weaving various kinds of figured fabrics, whether of silk, cotton, flax, wool, or other materials or mixtures of the same; part of which improvements are applicable to hand looms.—13th May.—6 mon. To Jacob Perkins, of Fleet-street, London, engineer, for his improved method of throwing shells and other projectiles—15th May.—6 months. To William Church, of Birmingham, Warwickshire, esquire, for certain improvements in the apparatus used in casting iron and other metals.—loth May.— 6 months. To John Holt Ibbetson, of Smith-street, Chelsea, Middlesex, esquire, for certain improvements in the production or manufacture of gas.—15th May. —6 months. -To Lemuel Wellman Wright, of Wellclose-square, Middlesex, engineer, for certain combinations and improvements in machinery for making pins. —15th May. —2 months. i To Joseph Luckcock, of Round Cottage, Edgebaston, near Birmingham, Warwickshire, gentleman, for his improvement in the process of manu- facturing iron.—15th May.—6 months. ; To William Henry James, of Coburg-Place, Winson-green, near Bir- mingham, Warwickshire, engineer, for his improved method of construct- ing steam-carriages useful in the conveyance of persons and goods upon highways and turnpike roads without the assistance of rail-roads.— loth May. 6 months. To Thomas Parkin, of Bache’s-row, City Road, Middlesex, merchant, for certain improvements in machinery or apparatus applicable to or em- ployed in printing. —15th May.—4 months. METEORO- ury| Apnoja urey| Apnoja f£pnojg Tey eurg] Aur103¢ auly Ie] Apnoyg| Apnoo Apnojg} Apnopod ‘wd wrer ‘Kpnojg| Apnoyo Apno[p are] Apnoig| Apno[g qWStu Au04s ‘Urey uIvy rel Dey Apnojg urey Apnolg| Apnoyg Apnojg| Apnoja aulLy ney ee Te Apnoyg} Apno9 sud ures ‘our eq ‘wd wer OUT IIe] ‘up ures ‘“ 2 : 37 T_|ZZOT/E1/19-P | 1P-2 I seal eeelereieesese OP. "NI os¢ GL-8P 9S eee bad | | eee "M 9S eeeeee PS I Oe oy A felipe ft 44 1 “a 67 I ‘a cP Leo ite “MN . 8h T|'|t {ft |t foo. |" | “AN vs Tat 0. ba es el Baie eee lee |e (000: co. O1Z-1|"** OdI-T |"** 0S. |0d- I ool. | : Dane ‘ 7 I 0fz- joe. I ove. |" I |t IT jo1o. |""° Pee leesl eee eesleeseee Co I | |T jovo. |°" wadleaatgalee be-laqanc Ps serrrr"lL IL {1 JOGO. jt. pola las ig lor ahcek celeelt [eesleedogg, free Lys £ jolo. jSL-0 a a Dalal 2 FP] os ARBRE Elzieiele| gz jos PIP IR a|") BA |” 8 *"sanold ¥.29 |L2-80/00-2S 91-08 16-62% £6.62 [6.66 88-62 ZL-6% 08-6% 96-62% 90-0€ VL-6@ 0S-6% QP-6% LL.6& 18:62 06-62% £0-0€ 0£.0€ 81-0f 88-6 66-66 68-64% OL-6% 99.6% 06.6% 198-62] :soser0ay GB va €@ (4g IZ 0G "PSSL jo sku IW'V “YD0[Q 0 14S1q ysvd-jyey ye ‘vu0ssoy ATaVL TWOMOTOXOULAN V THE PHILOSOPHICAL MAGAZINE AND JOURNAL. 30° JUNE 1824. LXVII. An Account of some Experiments made in order to de- termine the Velocity with which Sound is transmitted in the Atmosphere. By Ourntuus Grecory, LL.D., Associate Acad. Dijon, Honorary Member of the Literary and Philo- sophical Society of New York, of the New York Historical Society, of the Cambridge Philosophical Society, c. Secretary of the Astronomical Society of London, and Professor of Ma- thematics in the Royal Military Academy at Woolwich.* PPHE theoretical investigations of different philosophers, in order to ascertain the velocity with which sound is trans- mitted through the atmosphere, however ingenious and ele- gant some of them may be, seem to rest too much upon gra- tuitous assumptions, to allow any cautious inquirer after phy- sical truth to receive them unhesitatingly, except so far as they may be confirmed by accurate experiment. Unfortunately, too, the results of experiment present irregularities both for- midable and perplexing; since many of them cannot well be imputed to any want of skill or caution in the conductors of the inquiry. Feet per Second. Thus, Mr. Roberts assigns a velocity of . . . 1300 Mr. Boyle ey x21 200 Mr. Walkerand Duhamel . . . . . 1338 Mersenne in his treatise De Sonorum Natura, Causis et Effectibus . . . « « « 1474 The Florence Academy . . inches: alld 4 Cassini de Thury (Mem. Paris. Acad. ann. 70S aiaaiuKs on) ty 8s; eee IO Maeyeroat. . wide todaitgetss bap yslen Werkasa,o 300. iter gw itet Aoot fk. Hohindl he Boalleme nod sie) gies ol otin ptt liad= kL ovll0s Pictetlls pireuasa (Hom wii Teele SG Arago &c., from experiments in June 1822, give 337°2 metres at the temperature of +10° centigrade. . . . . . « 2106°32+}. * From the Transactions of the Cambridge Philoscphical Society for1824. + This is the last result of which I had heard previously to the com- mencement of my own experiments. Vol. 63. No. 314. June 1824. 3 E The 4.02 Dr. Gregory on the The theoretical formula most generally adopted, especially by continental philosophers, is this : Velocity in horizontal direction =333°44 met. / 1 ++00375¢; the metre being =3°2809 English feet, and ¢ denoting the indication of the temperature upon the centigrade thermo- meter. I am inclined, however, to think that this can only be re- garded as an approximative formula; and that we are not yet in a state to receive otherwise than as an approximation any — theorem which simply includes the variations of temperature. The air is subject to various classes of changes, indicated by the barometer, thermometer, hygrometer, and anemometer respectively, as well as others probably, for the ascertaining of which we have not yet any appropriate instrument. If we could select these, one by one, ad libitum, and carry experi- ments first through a moderate range upon the barometric scale, all the other probable elements of modification remain- ing constant; then, through a sufficiently extensive range upon the thermometric scale, the others remaining invariable, and so on; the question would soon be set at rest: but this is impossible. It becomes desirable, therefore, to augment the number of recorded facts, as they result from accurate experi- ments, in order that at some future (and it is hoped no very remote) time a cautious investigator may so select, compare, and classify them, as to deduce a more comprehensive and accurate theorem than is yet known. With a view to contribute, though in a small degree, to this purpose, I now present an account of a few experiments made by myself in the course of the present year. My objects were, to ascertain the velocity with which the sound passed over the surface of the earth, over the surface of the water; under different temperatures; in a quiescent state of the atmosphere, and in windy weather; by day and by night; the velocities of direct and reflected sound; and the velocities of sounds of different intensities and produced by different means. As yet the experiments have not been car- ried to their projected extent; but while I record the results thus far obtained, I lcok forward with hope, that in another year or two I shall be able to complete them satisfactorily. The instrument with which I measured the intervals of time, was one invented and made by Mr. Hardy, by means of which, with a little previous practice, I could measure an in- terval accurately to a tenth of a second, and approximatively to a twentieth of a second. The velocity of the wind was as- certained by means of an anemometer; and the barometer and thermometer were of the best construction. oo Velocity of Sound. 403 I employed no hygrometer (much as I wished it); for as yet L am not acquainted with any in whose results I should be inclined to confide. With regard to the distances between the stations at which the sound was emitted and heard, they were in some cases taken from the Ordnance Map of Kent, and verified by new operations; in others they were deter- mined by actual and careful measurement: in others by tri- gonometrical operations with accurate instruments. The whole were conducted with care; and it would be useless to enter into the detail of them. Friday, Jan. 3, 1824.—A musquet was fired from the bat- tery near the Royal Artillery Barracks, and the interval of time between the flash and sound was observed at two dif- ferent distances on the mortar-range, direction nearly north and south. January 3, half-past 2 P.M., barom. 29°7 inches, Fahr. therm. 45°, rather moist atmosphere, but no rain; very gentle wind blowing in direction nearly perpendicular to that of the range. Distance from musquet to my station 3600 feet. Six rounds fired: in one the interval of time employed by the sound in passing over the 3600 feet was doubtful: in the other five the intervals were 3°25, 3”°3, 3-25, 3-2, 3°26, the mean of these is 3252. 3600 3°252 Same day, 3 o’clock P.M., barom. 29°64 inches, Fahr. therm. 45°; atmosphere, wind and weather as before. Distance from musquet to station 3600 feet. Five rounds fired ; intervals 3""2, 3-2, 33, 3'*3,.3"-25; their mean 3'-25. 3600 325 Same day, half-past 3 P.M., barom. 29°64 inches, Fahr. therm. 45°; atmosphere, wind and weather as before. Distance from musquet to station 2100 feet. Eight rounds fired. Interval between flash and report in one case doubt- ful: the others were 188, 1°88, 1-9, 19, 1”°9, 19, 1°91; the mean 1/896. 2100 1-896 Thursday, Jan. 9, three quarters past 7 P.M, dark, but clear, star-light, frosty Bett Barom. 29°82 inches, Fahr., therm. 27°. Dry; no wind. Musquets fired from the battery, as before, distance 3600 feet. Six rounds fired, one doubtful. The other intervals be- 3E2 tween = 1107 feet, velocity of sound; therm. 45°. = 1108 feet, velocity of sound; therm. 45°. = 1108 feet, velocity of sound; therm. 45°. 4.04 Dr. Gregory on the tween observing the flash and hearing the report, were 3-25, 3°28, 3'°3, 3-3, 3°32; mean 3°29. 3600 3:29" The sound of the same charge, fired from the same mus- quet, was heard much more intensely on this clear frosty night than in the day-time of January 3, at the same distance, 3600 feet. Same day, January 9. Being anxious to extend the experi- ments to greater distances, I had previously applied to Ge- neral Ramsey, of the Royal Artillery, the Commandant of the Garrison here, for the use of cannons as well as musquets: these, with his accustomed courtesy and kindness, he imme- diately ordered to be at my disposal whenever I should need them in the course of my experiments. On the morning of this day, therefore, I chosé a station for the gun on the side of Shooter’s Hill, between Severn-Droog Castle and the 8 mile-stone on the Dover road. I selected three other stations from which the gun could be seen with a good Theodolite telescope ; one of these was at the entrance of the lane turning from the Dover road to Charlton, between ‘< the Sun in the Sands” and the 7 mile-stone; the second in the Kidbrook Lane which turns off from the Dover road be- tween the 6 mile-stone and “‘ the Sun in the Sands;” and the third on Blackheath, nearly in a continuation of the western wall of Greenwich Park towards the windmills. These three stations are probably 200 feet above the high water-mark in the Thames at Woolwich; and the station at which the gun was placed is still more elevated. The distances, as accurately measured, were, from the Shooter’s Hill station to that in Charlton Lane 6550 feet; from Shooter’s Hill to that in Kidbrook Lane 8820 feet; from the Shooter’s Hill station to that on Blackheath, 13,440 feet. The gun employed was a six-pounder, the charge of pow- der eight ounces. The serjeant-major who remained at the gun was directed to order the men to commence firing at a certain minute by his watch (which was previously made to _ agree with mine), and then to fire regularly a certain number of rounds at intervals of two minutes: this was the practice throughout the experiments, the gun was always pointed to- wards me, at a very small elevation, except it be otherwise expressed. January 9th, noon. Barom. 29:92 inches; Fahr. therm. 33°; weather dry, wind scarcely perceptible, a clear cloudless frosty day. : = 1094-2 feet, velocity of sound; therm. 27°. Six Velocity of Sound. 405 Six rounds fired. Interval of passage of sound from Shooter’s Hill to Charlton Lane, 5”*9, 6”:0, 5°9, 6”°0, 6'°0; 6-0, their mean 5’-92, distance 6550. 6550 59% Same day, January 9, half-past 12, barom. 29°86 inches; Fahr. therm. 33°; weather dry, wind scarcely perceptible. Six rounds fired. Result in reference to one, very doubtful. Intervals of passage of sound from Shooter’s Hill to Kid- brook Lane, were 7°95, 8:0, 8’°0, 8-0, 8°05; their mean 8”. Distance 8820 feet. st = 11023 feet, velocity of sound; therm. 33°. Same day, January 9, quarter past 1 PM., barom. 29°82 inches; Fahr. therm. 33°; weather dry, wind scarcely per- ceptible. Five rounds fired ; intervals of the passage of sound between the stations at Shooters Hill and Blackheath, 12-2, 12/25, 123, 12’24, 12""96; mean 12725, distance 13440 feet. 13440 122 4 (1098 + 11024-+4 1097)=10992 feet, mean velocity from the sixteen.rounds; therm. 33°. Monday, February 17, noon. Barom. 29°98 inches ; Fahr. therm. 35°. Air humid, but neither rain nor sleet; very gen- tle wind N.E. by E. Employed del/s on the mortar-range on Woolwich Common, lying nearly north and south. A bell rung at the north station, was heard by a soldier at the south station, who immediately rang another bell, having his arm elevated for the purpose, I stood by the soldier who rang the first bell, and measured the interval of time between the sound of the first bell, and the sound of the second bell when transmitted from the other station. By several preceding experiments, I estimated the time which elapsed between the moment when the man with the second bell heard the sound from the other, and struck the clapper against his own bell, finding it to be one-fifth of a se- cond; this, therefore, I deducted from the intervals which marked the passage of sound, before I recorded them, as be- low. Distance between the two bells 1350 feet; whole distance traversed by the sound 2700 feet. Intervals elapsed (cor- rected as above) in five experiments; 2”°5, 2°48, 244A, 2-46, 2-42; mean 2'°46. 2 - = 1098 feet, velocity of sound; therm. 35°. Same = 1098 feet, velocity of sound; therm. 33°. = 1097 feet, velocity of sound; therm. 33°. 4.06 Dr. Gregory on the Same day, quarter past 12, barom. therm, wind and weather as before. Distance between the two bells 1650 feet; whole distance 3300 feet. Intervals elapsed in four experiments, 30, 3'°0, 3-0, 3'"0. 3300 ; 2. >= 1100 feet, velocity of sound; therm. 35°. Same day, half-past 12, barom. therm. wind and weather as before. Distance between the two bells 1800 feet; whole distance 3600 feet. Intervals elapsed in five trials, 3/25, 3"-24, 3'"26, 3'°25, 325; mean 325. ans = 1108 feet, velocity of sound; therm. 35°. 4 (1098+1100+41108)= 1102 feet, mean velocity from this day’s experiments; therm. 35°. Friday, May 23. This morning there was a tolerably brisk wind blowing from the S.W. by W. nearly in the direction of my Charlton and Kidbrook stations from Shooter’s Hill. Of this I gladly availed myself, as the morning was in other re- spects favourable, in order to ascertain what would be the effect of such a wind upon the velocity. Cloudy, air humid, but no rain. I measured the velocity of the wind frequently with an ane- mometer, and found it vary between 22 and 26 feet, the mean 24 feet. The gun a six-pounder, charge 8 oz. of powder. 11 A.M. un at Shooter’s Hill, sound heard at Charlton Lane, distance 6550 feet. Barom. 29°66 inches. Fahr. therm. 58°, air hu- mid. Six rounds fired; the intervals were 6’*1, 6'"05, 60, 6-05, 6'"0, 6:04; their mean 6-037. 6550 6037 wind. Same day, quarter past 1 P.M., barom. 29°67 inches, Fahr. therm. 60°; air drier. Gun at Charlton Lane. Sound heard at Shooter’s Hill. Distance 6550 feet. Five rounds fired: the intervals were, 5°65 doubtful, 5’°8, 5°78, 5°76, 5"°78, omitting the first, the mean interval of the other four is 5°78. ges 11334 feet, velocity of sound, when aided by the wind. 4 (1085 +11333)=11093 feet inferred velocity of sound in- dependently of the wind; therm. 59°. And } (11334—1085) = 244 inferred velocity of the wind at = 1085 feet, velocity of sound, when opposed by the Velocity of Sound. 407 at the times of the experiment, supposing it to be nearly the same at both times. ‘This agrees quite as nearly as could be expected with the mean velocity of the wind determined by the anemometer. Same day, May 23, half-past 11 A.M., barom. 29°67 inches: Fahr. therm. 58°: air humid; wind as before. Before the gun was removed from Shooter’s Hill, six rounds more were fired. The intervals in which the sound reached Kidbrook Lane, were 8’1, 8'"125, 8°13, 8-15, 8-1, and one Ey doubtful. The mean of these is 8-121. Distance 8820 eet. = = 1086 feet, velocity of sound, opposed by the wind. Here the sound was but just audible, the wind diminishing its intensity exceedingly. Same day, therefore, the gun was removed to Kidbrook Lane, while I went back to Shooter’s Hill. Half-past 12, barom. 29-67 inches; Fahr. therm. 60°; air drier; wind as before. Six rounds were fired. The inter- vals between the flash and the report were 7'°8, 777, 7'"°8; 7°78, 7'°78, and one very doubtful; mean 7-77. a = 1136 feet, velocity of sound, when aided by the wind. 3 (1086 +1136)=1113 feet, inferred velocity of the sound independent of the wind; therm, 59°. 3 (1136—1086)=25 feet inferred velocity of the wind, nearly as before. The same day, May 23, in the afternoon, the wind sub- sided, so as not to exceed 6 or 8 feet per second, while the temperature of the air remained nearly the same. I anxiously availed myself of this opportunity to ascertain the velocity of the sound, when scarcely affected by the wind. Mortars and howitzers were firing from the battery, the former at an angle of 45°, the latter at low angles for Ricochet practice. At 33 P.M. when the barom. was at 29°68 inches, Fahr. therm. at 60°, the sun shining, I took a station 3100 feet from the battery, and in a direction nearly perpendicular to that of the wind, then gently blowing. I observed the intervals between the flash and the report, for six rounds, of which the first three were with howitzers, the next three with mortars; these were successively 2°77, 2’*76, 2-79, 2°79, 2/8, 2-8; their mean 2"*786. aq = 1112 feet, velocity of sound; therm. 60°. In these latter experiments the sound was very distinct and sharp : 4.08 Dr. Gregory on the sharp: the result, though drawn from a short distance, serves to confirm the preceding results on the same day. Thursday, August 7. On this day, which was cloudy, but with intervals of sunshine, I employed the same six-pounder as before, sometimes with charges of 8 ounces of powder, at others, when the distance required it, with 12 ounces. ‘The wind was quite brisk, varying in velocity from 30 to 35 feet, as determined by an anemometer. At eleven o’clock A.M., barom. 29°80 inches; Fahr. therm. 66°; air dry, cloudy, but sun shining; wind nearly opposing the motion of the sound, and having a velocity of 30 feet. Six rounds were fired from Shooter’s Hill. The intervals occu- pied in the passage of sound from thence to Kidbrook Lane, distance 8820 feet, were 8”"1, 8°15, 8°16, 8"°13, 8°13, 8°12; their mean, 8°13. 8820 : $13 = 1085 feet, velocity of sound, when opposed by the wind. Same day, August 7, quarter past 1 P.M., barom. therm. wind and weather as before. The gun being placed in Kidbrook Lane, I went to the station on Shooter’s Hill. Six rounds were fired, and the intervals occupied in the transmission of the sound were 77, 775, 7°68, 7°67, 7°72, 7°68; their mean 7"°7. =e = 11454 feet, velocity of sound, when azded by a wind of about the same velocity as the former. 2.(1085 +11454)=1115+ feet, velocity of sound ; therm. 66°, 4(11454—1085)=303 feet, velocity of the wind. Same day, August 7, half-past 11 A.M., barom. 29:80 inches; Fahr. therm. 64°, the wind blowing in the same di- rection as before, with (an estimated) velocity of 30 feet; air dry, cloudy, no sun. ‘The same six-pounder gun was fired from the Shooter’s Hill station with a charge of 12 ounces of powder, and I took a station on Blackheath 20 feet further than on January 9, its distance being 13,460 feet from the gun. Six rounds were fired ; one of the intervals was very doubt- ful; the others were 12/-4, 12'°38, 12/42, 12'°38, 1274, 124; their mean 12'°396. 13460 12:396 wind. Being fearful of bringing the gun to Blackheath, in the vi- . cinity = 1085°8 feet, velocity of sound when opposed by the Velocity of Sound. 409 cinity of so many carriages as were incessantly passing, I could not ere avail myself of the benefit of comparing the above in- tervals with those in which the direction of the transmission should be reversed. I venture, therefore, to add the velocity of the wind to that of the sound, as obtained by the experi- ment, and thus obtain 1085°8+30=1116 feet nearly, for the velocity of sound, the therm. standing at 64°. Monday, August 18. On this day, the same six-pounder gun was placed upon the wharf by the side of the Thames in the Royal Arsenal, and I took a station at. the opposite extremity of the Gallion’s Reach, not far from the mouth of Barking Creek; the distance from the gun was 9874 feet, the time of high water there, on that day, was about 11 o'clock A.M. At half past 11 A.M., barom. 29°84. inches; therm. 66°; air dry, sky rather cloudy: very gentle wind nearly perpen- dicular to the line of transmission of the sound. Six rounds were fired with the muzzle of the gun towards me: the inter- vals were 8-8, 8'"84, 8'-86, 8°86, 8°83, 8°85; their mean 8°84. At three quarters past 11 A.M., barom. &c. as before ; six more rounds were fired, the gun muzzle being directed from us (up the river) in a horizontal angle of about 140 degrees : the intervals were 8/86, 8°84, 8°82, 882, 8-85, 8°86; their mean 8”-841, 9874 884 surface of water. Although there was no perceptible difference in the mean intervals occupied by the transmission of sound, in. the two different directions of the gun, yet there was a considerable modification of the intensity; the sound being much weaker when the gun muzzle was directed westerly, up the river, than when it was pointed down Gallion’s Reach, towards the place where I stood. In the former case, too, besides the first report, which was marked and distinct, though compa- ratively feeble, there was a series of audible re-percussions, at intervals of about a tenth of a second, and gradually dying away: these, I conjecture, were reflected sounds from’ the faces of storehouses and other buildings standing on or near the side of the river at Woolwich. Same day, August 18, one o’clock P.M., barom. 29°82 inches, Fahr. therm. 66°; fair, but cloudy; scarcely any wind: I took a station on the’ Essex bank of the Thames perpendi- cularly opposite the large storehouse on Roff’s Wharf at Woolwich, in order to ascertain the interval occupied by both Vol. 63. No. 314. June 1824. 3F the = 1117 feet, velocity of sound; therm. 66°, over a 410 Dr. Gregory on the the direct and the reflected transmission of the sound from a musquet fired by my side, and returned in an echo from the front of the said storehouse. ‘The distance from my station to the front of the storehouse, determined carefully by a tri- gonometrical operation, was 1523 feet. Of eight rounds fired from the musquet, I failed twice in the appreciation of the interval between the sound and the returning echo, from a very wrong estimate of its probable duration; and that from an erroneous impression as to the time observed by Dr. Derham in a similar experiment*. Of the remaining six rounds, the musquet pointed across the river, the intervals were 2'°7, 2'°'75, 2'°74, 2°72, 2"°75, 2°74; their mean 2”*73° Next, three rounds were fired, the musquet being, pointed directly from the river; the intervals were 2""7, 2"*73, 2'°76 ; mean as before. Lastly, four rounds were fired along the bank, at an elevation of about 45°; the intervals were 275, 2'°7, 2'°73, 2"°74; mean as before. ‘ Distance occupied by the direct and the reflected sounds 3046 feet. gag 1116 feet velocity of sound across a surface of -wa- ter, half direct, half reflected; therm. 66°. The near agreement of this with the former result on the same day, serves to confirm the opinion that direct and re- flected sounds move with the same velocity. Thursday, August 21, three o’clock P.M., barom. 29°86 inches, Fahr, therm. 64°; clear sunshine; wind scarcely per- ceptible, westerly. Mortars were firing from the battery, and I took a station 3900 feet south of it. I observed the intervals between the flash and the report in six successive rounds: they were 3'"5, 35, 3'°48, 3°52, 35, 3'"5, respectively; the mean being Side sy: = cl m = 1114¢ feet, velocity of sound, therm. 64°. These are all the experiments in reference to the velocity * He made it 3 seconds, by means of a half-second pendulum. My erroneous recollection of his experiment led me to anticipate an interval of between 4 and 5 seconds. I could not account for the supposed dis- crepance until after my return home, when, on examining Derham’s paper, and computing the real breadth of the river from my trigonometrical ope- ration, I found the correspondence of the two experiments to be quite as great as could be expected, considering the different natures of the chrono- meters employed, and the varying breadth of the river. of Velocity of Sound. 411 of sound, as transmitted through the atmosphere, which I have yet been able to make. Their chief results may be brought into one view as below. Feet. Velocity of sound, Fahr. therm. 27° w+... 1094-2 — ditto 33. | +++ |¢.G9 |¢¢|colo9| £6.62 | 18-08 |t ce SPL “104, —oury meq} **' | ** 16.29 |€9|69!LS] 0%-0€ | LG-o€ |*** “as aug) eg “| 19 |9S|69,Lb| $z-0€ | b9.08 |*"* 82-0 | “ALN oul] Teg os SS |PSIP9 GS) S1-0F} oSro€ fein fet py | IN . ar: fiz] ©} weviel mea | lala = H pide | ‘uopuoy| © y wD) 5] o) > “aes ‘adios Zi 5 ge ee e = 9 ra BS loel else BE)E 8 a |S) SF < ae Bs le vs eta eee g| Ee 8 eg |2s| 2 5) : PL" Fl Noanorg| 28 ‘Seuour |e | Ble" Pe Ab Tale 5 “MAHLVE AA Ur ‘19j}aUIOIBgT “NIVY ‘sajauloueyy,| JO FIO FT *sanoTy WV ‘OTD 0 I4SIGT ysed=syey 4e ‘LUOssoy a MOMOT WP TIVEA “AY pun ‘uopuorT ur AUrQ “py “wodsoy qo AINUNg “sq fo suoynasasgg oy} Fusadwoo >A 1GVL TVOIDO'TOUOULAN V { 474 J INDEX to VOL. LXIII. —>— A CID, benzoic, in the fruit of the clove-tree, 73 Aéronautic ascent, 464 Es candidum of Pliny, 126 Algebraic functions, their application to parallel lines, 161, 246 Algebraical notation, 68 Ampullariade. On some new species of, 276 Analysis of the Maine meteorite, 19 ; of the ore of white copper, 120; of lamellar pyroxene, 131 ; of hyalosi- derite, 186; of iron slags, 188; of new minerals, 236; of green felspar, 283; of Cheltenham water, 312; of black currant wine, 446 Anchors, improvement in, 144 Antarctic discoveries, 462 Anthracite of Pennsylvania, 234 Antimonium tartarizatum, 293 Apennines, on the geology of, 278 Ascidia, New species of, $21 Asilus of the Romans, 228 Asinus Burchelilii, 451 Astronomical information, 65, 230, 252, 392, 457 Astronomical observations, Bessel’s, 427 Astronomical refractions, 418 Atmosphere, on the dispersive power of the, 192, 328 Babbage’s calculating machine, _ 355 Baily, (F.) on the opposition of Mars, 50; on the circular micrometer, 177 ; on Babbage’s calculating machine, 355; on the occultation of Georgium Sidus, 458 Bakewell, on the manufacture of salt, 86 Bangma’s method of solving equations, 369 Barlow’s variation correcting plate, 392 Batrachian animal, 325 Benxoic acid, 73 Bessel on the readings of thermometers, 307 Bessel, Introduction tohis Astronomical Observations, : 427 Bessel on Reichenbach’s circle, 348 Bevan (B.) on the adhesion of nails, : ; 168 Binomial calculus, 443 Black currant wine, 446 Books, new, 52, 135, 219, 284, 375, 447 Bournon (M.) on the gangues of Ceylon spinelle, 3 Bowdich, (African trayeller,) death of, 238 Brandes on white copper, 120 Brayley on the origin of meteorites, 385 Breese, or Brize 228 Brem, or Brom, a Teutonic root signi- fying to prick, 229 Brisbane river, discovery of, 459 Burnett, (Dr. W.) on mercurial va- pours, 42 Cacti, new descriptions of, 40 Canals from the Black Sea to the Baltic, 393 Cancer, cases of, 397 Capstans, improvement in, 145 Cast-iron, test of its quality, 54 XwAxos Moccvvoixwy of Aristotle, 126 Cheltenham water, its contents, 312 Children and Daniell on Deebereiner’s eudiometer, 72 Chloraster, description of, 102 Chronometers, rate of, its variation with the density of their medium, 311 Circle, on the, 368 Clove-tree, benzoic acid in, 73 Comet of 1823-24, elements of, $10 Comet, account of, 63, 147; of Sept. 1822, 65 Copper sheathing, preservation of, 60 Copper, white, 119 Covelli. and Monticelli on the pheeno- mena of Vesuvius, 46 Cranberries, 73 Cromer Cliff, geology of, - 81 Curtis's British Entomology, 57 Daniell and Children: on Deebereiner’s eudiometer, 72 Davy -(Sir H.) on the preservation of copper sheathing, 60 Denmark, education in, 396 Debereiner’s eudiometer, 71, 72 Earth, figure of the, 66, 339 Earth, sinking of the, 395 Earthquake, 394 ; at sea, 394 Earthquake in India in 1819, 105, 170 Earthquakes with meteors, 114, 173 Earthquake at Colombo, 74 ; in Chili, 227; in Jamaica, 463 Edinburgh Phil. Trans., 450 Electro-magnetical experiments, 95, 266 Electrometer, single-leaf, 244 Entomology, Thunberg’s cabinet of, 74 Equations, method of solving, 869 Eudiometer of Deebereiner, Ti, a2 Expeditions, Northern, 69; Southern, 462 IND eecadety (M.) on Cheltenham water, ; 312 Feldspar, green, analysis of, 283 Fir-trees, pierced by an insect, 299 Flora, Fauna, and Pomona, calendar of, 315, 397, 470 Flora, the English, Notice of, 219, 284 Forbes (John), death of, 314 Forster (Dr. T.) on the powers of the atmosphere, 192; on the peculia- rities of the stars, $28; calendar of Flora, 315, 397, 470 Frauenhofer on the circular Lap ag meter, 210 Gad-fly, 228 Gadinia, a new genus of shells, 275 Galvanic deflagrator, 241 Gauge ae compressed steam, &c., 36, 92, 190 Gauging, new method of, 415 Geological atlas, 447 Geology of Cromer Cliffs, 81; of Russia, 225; of the Apennines, 278; of New South Wales, 380; of the Ponza Islands, 454; of Hastings, 455; of the Coasts of the English Channel, 456 Georgium Sidus, occultation of, | 458 Gmelin on Debereiner’seudiometer, 71 Gompertz’s differential sextant, 458 ron | (J. Edw.) zoological notices, 274 Green Feldspar, 283 Gregory (Dr. O.) on the velocity of sound, 401 Hare (Robert, M.D.) on the galvanic deflagrator, 241; on a single-leaf electrometer, 244; on the eombus- tion of iron by sulphur in vapour, 245; on impregnating water with iron, 245 Harlan (Dr. R.) on Amphiuma means 325 Harley (C. G.), on black currant wine, 446 Haussmann ( Prof.) on the geology of the Apennines, 278 Hawkes’s improved anchors, 144; his improvement in capstans, 145 Haworth (A. H.) on Narcissex, 7, 102, 136; Cactus and Mammillaria, 40 Herapath (J.) on thermometers, 8 Hopeite, a new mineral, Hutton’s tables, errors in, 357, 427 Hyalosiderite, a new mineral, James's Powder, 295 India, earthquake of 1819 in, 105, 170 “ Infinite.’ On the application of the term, 372 Tron in black currant wine, 447 Ivory (J.) on the figure of the earth, 339; on the astronomical refrac- E X. 475 tions, 418 ; on the new tables of re- fraction, 261 Kefferstein (C.) on white copper, 119 meth (M.) and M. Pasquich, 232 Laplace (M. de) Mécanique Céleste, 67 Lesueur (C. A.) on Ascidia, 321 Logan Stone in Ccrnwall overturned, 313 Lowry, Wilson, Esq. death of, +469 MacLeay (W. S.) on Cistrus and Asi- lus, 228 Magnetic needle, effects of caloric on, 130 Magnetism, apparent, of titanium, 15 Mammillarie, new descriptions of, 40 Mars, opposition of, 50, 233 Maseres (Baron) death of, 398 Massotii (M.) on the motion of comets, 457 Mathematical information, 68 Megalosaurus, 225 Mercurial vapours, effect of, 42 Meteor, $93 Meteorite of Maine, analysis of, 16 Meteorites, 233; origin of, * $86 Meteorology, 76, 80, 149, 160, 240, $20, 400, 465, 470 Meteors, accompanying earthquakes, 114, 173 Mezico, silver mines of, 140 Micrometer, circular, 177, 210 Mineral, a new hyalosiderite, 181 Minerals, new analyses of, 236 Monticelli and Covelli on the phzno- mena of Vesuvius, 46 Mount Rosa, height of, 463 Murray (J.) on the deviation of the magnetic needle, 130 Nails, on the adhesion of, 168 Narctssee, new species of, 7, 102, is6é Natural History, works on, 57, 136, 224, 297, 375, 451 Nautical Almanac, 374 Netherlands, universities in, 237 New South Wales, geology of, 380 New South Wales, discoveries in, 459 @strus of the Greeks, 228 Organic remains from Cromer, 82 Orrery, new pendent, 233 Oxley’s (Mr.) discoveries in New South Wales, 459 Parallel lines, application to them of algebraic functions, 161 Parallel straight lines, on, 100, 271 Pasquich (M.) and M, Kmeth, 232 Patents, 75, 148, 238, 318, 399, 473 “ Pharmacopwia of London, 1824,” ce Plesiosaurus, 13 Pond on the parallax of the stars, 68 Population, 395 Precession, new tables of, 392 Pulvis antimonialis, 295 476 Pyrozene lamellar, description of, 131 ; analysis of, 131 Reade (Dr. J.) his theory of telescopes, 20 Refractions, astronomical, 418 Reichenbach’s astronomical i instruments, 427; his circle, 348 Russel (H.) pressure-guage, -~ 92 Russia, geology of, 225 Sabine (Capt.) on the temperature of the sea, 69 Salt, faggot manufacture of, 86 Sea, Caribbean, temperature of, 69 Seaward (Sam.) steam-gauge, 36, 190 Sextant differential, 458 Silver mines of Mexico, 140 Sirer juvencus, - 299 Smith (Sir J. E.) “ English Flora,” notice of, . 219, 284 Smith's Geological atlas, 447 Society, Royal, 59, 136, 224, 299, S78, 452; Linnean, 60, 137, 228, 299, 378, 453; Astronomical, 61, 1383, 229, 301, 382, 457; Horticultural, 61, 300, 379, 457; Meteorological, 61, 140, 383 ; Medico-botanical, 62, 302; Royal Academy of Sciences, Paris, 62, 305 ; Geological, 137, 225, 380, 454; Medical Society of Lon- don, 302; Asiatic: Qestion relative ~ to the charter, 303; of naturalists of Moscow, 386; Moscow Agricul- tural, 388 Sodalite, action of light on, 464 Sound, on the velocity of, 401 Spinelle of Ceylon, gangues of, 30 Steam, measure of the force of, 259 Steam navigation to India, a Steam pressure-gauge, Struve (Prof, ) on the parallax of é stars, 66 Sturgeon (W.) electro-magnetical ex- periments, 95; his electro- and ther- momagnetical ‘experiments, 266, 269 Tabanus, 228 INDEX. Tables of refraction, on the new, 261 Taylor (Rich.) on Cromer Cliffs, 81 Telescopes, Dr. Reade’s theory of, 20 Temperature of the Caribbean Sea, 69 Thunberg’s cabinet of entomology, 74 Thermo-magnelic experiments, 266 Thermometers, irregularities of, 8; me- thods of ascertaining the corrections of the readings of, 307 | Tiarks (Dr.) on the figure of the earth, Titanium, magnetism of, 15 Tredgold (‘T.) on the strength of cast- iron, 52 Turquoise, mines of, 455 Vanuxem (L.) on lamellar pyroxene, 131 Velocity of sound, 401 Vesuvius, phenomena of, &c. 46 Vigors (N. A.) on natural affinities of birds, 453 Universities in the Netherlands, 237 Voyage of Discovery, French, 235 Utting (J. ) on Hutton’s tables, 427 Walchner (Dr.) on hyalosiderite, 181 Walsh (John) on parallel straight lines, 100, 271 ; on the circle, 368; on the binomial calculus, 443 Webster (J. W.) on the meteorite of Maine, 16 Weights, standard, 237 Wernerian Transactions, Wheat, history of its prices, &c. 56 White copper, 119; analysis of the ore, 120; of China, 128 Wiseman (W.) on Dr. Young’s method of gauging, 415 Wollaston on the magnetism of tita- nium, 15 Young (Dr.) new method of gauging, 415 Zahrtman on instrument-makers at Paris, 252 Zoological notices, 274 Zoological Journal, $75, 451 Zoophytes, on the characters of, 274 END OF THE SIXTY-THIRD VOLUME. as z= S57) <0 NYRAL WS ee eee — LONDON: FRINTED BY RICHARD TAYLOR, SHOE-LANE. 1824. Just published, in one thick volume, Price 10s. 6d. boards, KETCHES of the PHILOSOPHY of APPARITIONS; or An Attempt to trace such Illusions to their Physical Causes, By SAMUEL HIBBERT, M.D., F.R.S.E., Secretary to the Society of Scottish Antiquaries, Member of the Royal _ Medical and Wernerian Societies of Edinburgh, of the Philosophical Society of Manchester, &c. * Published by Oliver and Boyd, Edinburgh; and G. and W. 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A Plate illustrative of Mrs. Insetson’s Paper On the Flower-buds of Trees passing through the Wood.—A_ Plate descriptive of the Instruments employed in determining Altitudes from the Trigono- . _ metrical Station on Rumbles Moor, Yorkshire.—A Plate illustrative of _ Mr.Ivory’s Theory of Parallel LinesinGeometry; Mr. Leeson’s Safety Blowpipe Appendages; Mr. Moore’s new Apparatus for restoring the Action of the Lungs in Cases of suspended Respiration ; and Dr. Reape’s Communication on Refraction.—A Plate illustrative of a curious Electro. magnetic Experiment by Mr. Bartow; and Mrs. Issetson’s Paper on- the Perspiration alleged to take place in Plants.—A Plate illustrative of Mr. Marsn’s Paper on a particular Construction of M, Ampere’s Ro- tating Cylinder. - ‘ eert: = Vol. LX. A Plate illustrative of Mrs. Insetson’s Paper On thePollen of Flowers.—A Plate illustrative of a Paper by Mr. R. Tayzor, of Nor- _ wich, on Fossil Bones from the Norfolk Coast.—A Plate illustrative of a _ Paper by F. Bairy, Esq. on the Stars forming the Pleiades—A Plate. - illustrative of Prof. Amuci’s New Sextant. ; Vol. LXI. Engravings—1. Illustrative of Mr. TREpGoLp’s Paper on. the Flexure of Astronomical Instruments.—2. DzurBRovca and Ni. . cHoLs’ Apparatus for Madame Gervais’ New Method of Fermentation. _ —A Plate illustrative of Mr. R. Tayior’s Geological Section of Hun- stanton Cliff, Norfolk.—A Plate illustrative, of Mr. Tarum’s Communi- cation on Electro-Magnetism, Mays me Vol, LXU. A Plate illustrative of Professor Hare's Communications on Electricity, and on. the Self-acting Blowpipe.—A Plate illustrative _ of Mr. Brunet’s new Mode of Tunnelling, and of his Proposal for a _ Roadway under the Thames.—A Plate illustrative of M. 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Sturn, Professor of © Chemistry in Yale College, on Some improved Forms of the Galvanic - “~~ Deflagrator ; on the Superiority of its deflagrating Power: Also, an Account of an improved Single-leaf Electrometer ; of the Combus- tion of Iron by a Jet of Sulphur in Vapour; and of an easy Mode of * imitating native Chalybeate Waters ./.................-.. page 241° a XL. Further Remarks on the Theory of Parallel Lines........ 246 XLI. Onthe Mathematical and Astronomical Instrument Makers ; at Paris. By Lieut. ZAHRTMANN,...........0.5, 823, )1.00. : = 252 XLII. Suggestions regarding some probable Sources of Error in — the usual Modes of ascertaining the Force of Steam.............. 259. XLII, Remarks on an Article published in No. 23 of the Journal of Science, and treating of the New Tables of Refraction. By J. Ivory, fisg. NEACE IR Bio ooo sea pipe ee OE 4, 0 oh 261 XLIV. Electro- and Thermo-magnetical Experiments. By Mr. Wittram STURGEON....... Pe eee) ye 8 SA eee 266 XLV. 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A Plate illustrative of Mrs. Isserson’s Paper On the Phy- of Botany.—A Plate illustrative of Mr. Hau’s Percussion Gun- ek; of Dr. Krrewter’s Pancratic Eye-Tube; and of Mr. Parx’s ring Blocks.—A Plate exhibiting Sections, &c. of Mr. Matam’s im- wed Gas- Meter. —A Plate exhibiting the Discoveries made by Capt. Vol. LVIIL A Pilate illustrative of Mr. Gro. Innes’s Calculations of “Annular Eclipse of the Sun, which will happen on the 15th of May 36.—A Plate descriptive of the Hydrostatic Balances of Isaran teens and Dr. Coares.—A Plate illustrative of * An Introduction to : Knowledge of Fuaguses.”"—A Plate illustrative of Professor Davy's ctometer, and of Mr. Joun Murray's portable Apparatus for restor- : the Action.of the Lungs.—A_ Plate by Poarsr, illustrative of Mr. WOOLCRAFT’s Account of the Native Copper on the Southern Shore of * ike Superior ; and of Dr. Mirar’s Observations and Experiments on » Rose of Jericho.—With a Portrait of the Eprror, engraved by aomson from a Painting by Frazer ;—anda Plate by Porrss, illus- itive of Mr. Lseson’s Appendage to Torrt’s Blowpipe, Vol. LIX. A. Plate illustrative of Mrs. Isssrson’s Paper On the lower-buds of Trees passing through the Wood.—A Plate descriptive the Instruments employed in determining Altitudes from the Trigono- etrical Station on Rumbles Moor, Yorkshire. —A Plate illustrative of r.Ivory’s Theory of Parallel Lines inGeometry 5 Mr. Leeson’s Safety fowpipe Appendages; Mr. Moors’s new Apparatus for restoring the ction of the Lungs in Cases of suspended Respiration ; and Dr. Reaps’s ymmunication on Refraction.—A Plate illustrative of a curious Electro- agnietic Experiment by Mr. Bartow; and Mrs, Isserson’s Paper on e Perspiration alleged to take place in Plants.—A Plate illustrative of . Maxsu’s Paper on a particular Construction of M. Ampsre’s Ro- fting Cylinder. Vol. LX. A Plate illustrative of Mrs. Inssetson’s Paper On thePollen 1{Flowers—A Plate illustrative of a Paper by Mr. R. Taytor, of Nor- sh, on Fossil Bones from the Norfolk Coast.—A Plate illustrative of a per by F. Barry, Esq. on the Stars forming the Pleiades.—A_ Plate astrative of Prof. Amict’s New Sextant. ‘ol. LXI. Engravings—1. Illustrative of Mr. TREDGOLD’s Paper on e Flexure of Astronomical Instruments.—2. Deursroveg and Nr. 4oLs’ Apparatus for Madame Gervais’ New Method of Fermentation. -A Plate illustrative of Mr. R. Taytor’s Geological Section of Hun- anton Cliff, Norfolk.—A Plate illustrative of Mr. Tarum’s Communi- tion on Electro-Magnetism, R rol, LXU. A Plate illustrative of Professor Hars’s Communications a Electricity, and on the Selfacting Blowpipe.—A Plate illustrative f Mr. Brunet’s new Mode of Tunnelling, and of his Proposal for a foadway under the Thames.—A Plate illustrative of M, Becqugret’s xperiments on the Development of Electricity by Pressure. —A Plate lustrative of Mr. Bartow’s Experiments on Mr. Marsn’s Thermo- ectric Apparatus.—A Plate illustrative of Mr. Seawann’s Observa- -LXUL. A Plate illustrative of Mr. Gomrrrtz’s Method of de- nding Ships and Fortifications; and a Cut of Mr, Seawarp's Pressure fauge.—A Plate illustrative of Mr. Ricuarp Tayton’s Paper on the ipper Marine Formation in the Cliffs near Cromer.—A Plate Lllustrative . WaAtcuner’s Examination ofa new Mineral named Hyalosiderite ; id of Mr. Baity’s and M. Fravennorer’s Accounts of the Circular icrometer —A Plate illustrative of Professor Hanrx’s Single-leaf Elec~ as mig “> AS ie eh ; etry . “ ye Sos Laerey : ~¥e : 3 , S| Vox. 63s... Philosophical Magazine... ApRiL 1824, | Contents.or NuMBER 312... -.. > 3 XXXIX, Letter from Ropert Hare, M.D. Professor of Chemi- is stry in the University of Pennsylvania, to B. SILLIMAN, Professor of *» ~ “ Chemistry in Yale College, on Some improved Forms of the Galvanic a Deflagrator ; on the Superiority of its deflagrating Power: Also, q an Account of an improved Single-leaf Electrometer ; of the Combus- ; tion of Iron by a Jet of Sulphur in Vapour ; and ofan easy Mode of * | a imitating native Chalybeate Waters ....................2. page 241° XL. Further Remarks on the Theory of Parallel Lines........ 246 XLI. Onthe Mathematical and Astronomical Instrument Makers * at Paris. By Lieut. ZAHRTMANN.............. Ba seh chet Seow XLII. Suggestions regarding some probable Sources of Error in the usual Modes of ascertaining the Force of Steam.......... vee 269 XLII. Remarks on an Article published in No. 23 of the Journal of Science, and treating of the New Tables of Refraction. By J. Ivey, Bis, NASP RBs vs ede Oe eh 8 .. ‘261 XLIV. Electro- and Thermo-magnetical Experiments. By ‘Mr. WILLIAM STURGEON...... SESE he os ed thy ieee a ales 266 XLV. Description of a Rotative Thermo-magnetieal Experiment. Kees | By Mr..Wiriibtam STuRGHON. ) gies asin es cet vents dee ey so: 2695 5 XLVI. On Parallel Straight Lines. By Joun WAtsu, Esq.... 271 XLVII. Zoological Notices.. By Mr. Joun Epwarp Gray, ~< 274 XLVIIL. Analysis of Professor Hausmann’s Essay on the .Geo- logy of the Apennines... ... NAseie tare te SR Cee tia ei bat nite 278 XLIX. Chemical Examination of Green Feldspar from Beverly, Massachusetts. By J.W. Wesster, M.D........... 05500000, 283 L. Notices respecting New Books:—Sir J. E. Smrrn’s English Flora; Pxituies’s Translation of the London Pharmacopeia; Ana- lysis of Periodical Works of Natural History..............-. 284— 299 LI. Proceedings of Learned Societies :—Royal Society ; Linnzan Society ; Horticultural Society ; Astronomical Society; Medico- Botanical Society; Medical Society of London ; Asiatic Society— Question relative to the Charter; Royal Academy of Sciences at =~ Petia wet ie d °c atvlal «hoa cee y Ps we Ona a als aie, eae RD 299—307 LII. Intelligence and Miscellaneous Articles :—Brssrx’s Method of ascertaining the Corrections of the Readings of Thermometers; — Elements of the Comet of 1823—24, by various Computers; Ano- = maly in the Figure of the Earth; The Rate of a Chronometer == yaries with the Density of the Medium in which it is placed ; Note ~ on the Existence ofa Nitrate and a Salt of Potash in Cheltenham Water, by M. Farapay, &c.; The Logan Stone in Cornwall over- turned; Obituary—Mr. Joun Forses; Calendar of Flora, Fauna, and Pomona, at Hartfield in Sussex ; Additionsto Professor HarE’s ~ Paper; List of New Patents; Meteorological Table, &c.....307—320 a *,* Communications for this Work, received by the Editors, — : 88, Shoe-Lane, will meet with every attention. Ppa Vol. LVI. A Plate ‘Vnstrative of Mrs. IpBETSON’s Paper On the Phy- logy of Botany.—A Plate illustrative of Mr. Hatv’s Percussion Gun- ock; of Dr. Kircutner’s Pancratic Eye-Tube; and of Mr. Park’s jocks. —A Plate exhibiting Sections, &c. of Mr. Maram’s im- Meter.—A Plate exhibiting the Discoveries made by Capt. ar Sea. . ie 4 A Plate illustrative of Mr. Geo. Innes’s Calculations of . ie Annular Eclipse of the Sun, which will happen on the 15th of May 36.—A Plate descriptive of the Hydrostatic Balances of Isaran ‘uxens and Dr. Coates.—A Plate illustrative of “An Introduction to e Knowledge of Funguses.”—A Plate illustrative of Professor DAvy’s - actometer, and of Mr. Joun Murray's portable Apparatus for restor- s.—A Plate by Porrer, illustrative of Mr. "HOMSO ing by Frazer ;—anda Plate by Porter, illus- Irative of Mr. Lerson’s Appendage to Torrt’s Blowpipe. : Vol. LIX.. A Plate illustrative of Mrs. IsseTson’s Paper On the Flower-buds of Trees passing through the Wood.—A_ Plate descriptive If the Instruments employed in determining Altitudes from the Trigono- aetrical Station on Rumbles Moor, Yorkshire.—A Plate illustrative of Mr.Ivory’s Theory of Parallel Lines inGeometry; Mr. Leeson’s Safety owpipe Appendages; Mr. Moore’s new Apparatus for restoring’ the ction of the Lungs in Cases of suspended Respiration ; and Dr. REaDE’s A Plate illustrative of a curious Electro- gnetic Experiment by Mr. Bartow; and Mrs. Iszerson’s Paper on Perspiration alleged to take place in Plants——A Plate illustrative of Marsn’s Paper on a particular Construction of M. Ampgre’s Ro- Plate illustrative of Mrs. Inzetson’s Paper On thePollen i Engravings—1. Illustrative of Mr. TREDGoLD’s Paper on e Flexure of Astronomical Instruments.—2. Deursroveg and Ni- HOLS’ Apparatus for Madame Gervais’ New Method of Fermentation. —A Plate illustrative of Mr. R. Taytor’s Geological Section of Hun- tanton Cliff, Norfolk.—A Plate illustrative of Mr, Tatum’s Communi- pation on Electro-Magnetism. } Vol, LXIL A Plate illustrative of Professor Hare's Communications m Electricity, and on the Self.acting Blowpipe.—A Plate illustrative of Mr. Brune’s new Mode. of Tunnelling, and of his Proposal for a Roadway under the Thames.—A Plate illustrative of M. BecQuEREL’s ixperiments on the Development of Electricity by Pressure. —A Plate strative of Mr. Bartow’s Experiments on Mr. Marsu’s Thermo- ctric Apparatus.—A Plate illustrative of Mr. Seawanp's Observa- Htions on Suspension Chain Bridges. Vol. LXUI, A Plate illustrative of Mr. Gomrertz’s Method of de- ending Ships and Fortifications; and a Cut of Mr. SEAwWARD’s Pressure Zauge.—A Plate illustrative of Mr. Richarp Taytor’s Paper on the er Marine Formation in the Cliffs near Cromer.—A Plate Illustrative f Dr. WALCHNER’S Examination ofa new Mineral named Hyalosiderite ; nd of Mr. Barry's and M. Fravennorer’s Accounts of the Circular licrometer —A Plate illustrative of Professor Hare's Single-leaf Elec- eter and improved Deflagrators, < be ak - i Paaateuy a Eso eC aa Vor.63. Philosophical Magazine. = 182. CK nis OF Naaru 313, ; Vee Lm Descriptions of several new Species of Ascidia.. ‘By C. A, ow LESUEUR ....... acrid Bee pect eee tc eee tes ‘ie -. page _ LIV. Dissection of a Batrachian Aaiuaiat in a eis State. By... pie NO Ste . = ers < - Ricuarp Haran, M.D. Professor. of ‘Comparative Anatomy to. the Philadelphia Museum ven 09 6. on. ts oe oe Sohne 2 eat LY. On the Dispersive Power of the Atmosphere, and’ on the Peculiarities of Stars. By Dr. T. Forster ............ Aa ay) vo meer | LVI. Remarks on the Theory of alg Figure of the Earth. By a Ji Fvornyy Esq. MiAwe FBS. 35085 oot ted Gee a 33a LVII. Examination of the Divisions of Reicuensace’s Circle _ at the Observatory of Kénigsberg. By M. Besse. |. . EF ig Mea Fe in the University of Pennsylvania... ..0..0. 66.0000. ccue eee eees 364 ‘nomical Society; Meteorological Society ; Imperial Society of Na>- LVIIL On Mr. Bapgace’s new Machine for calculating and printing Mathematical and Astronomical. Tablea._ From a. J Baiy, Esq. F. R.S. and LS... ... NAY Seon a eT Ferg tht Sak ~ Shoe LIX. A brief Account of some Electro- -magnetic aad Galvanic | Experiments. By Ropert Hare, M.D. Professor of Sat. | LX. On the Circle. By Jonw W ALSH, Esqe ares 1 nage t aa | LXI. On a Method of finding the Limits of the Roots of the higher Powers of Numerical Equations. By Mr. J. Rowsotuam. 36 LXIL. On the Application of the Term “ Infinite.” 230.0. 00u0 374 LXIII. Two Lines from the Naptical sero gee addressed to v4 Pe VOI id Peck 2 eh Pela ola NE TS Pc a ee 374 | LXIV. Notices respecting } ‘New Books ee of Periodical | Works on Natural History. /...- +... 4+.- 0. tee sec i eens Pee, | ‘LXV. Proceedings of Learned Societies : —Royal Society ; Lin. al nzan Society ; Horticultural: Society ; ; Geological Society; Astro- — turalists of Moscow ; Imperial Agricultural Society of Moscow. 878—39] } LXVI. Intelligence and Miscellaneous Articles :—New Tables of 4 Precession, Aberration and Nutation; Nautical Magnetic Premium; sees | Steam ‘Navigation: to India; Steam Vessels in the Netherlands; _ } Canals for uniting the Black Sea to the Baltic ; Meteor ; Earthquake: _ | felt at Sea; Earthquakes ; Sinking of the Earth ; Statistics ; Educa- | 4 tion in Denmark ; South America; Cancer; ‘Calendar of ‘Flora,’ . 3 Fauna, and Pomona; at Hartfield in Sussex ; Obituary—Baron Z| Maseres ; ; List of New Ravents Meteorological Tables els . 892—401 38 Shoe-Lane, will meet with every attention. _ ( | +,* Commiinications for this Work, recbvall by the aie y i . / y of J RICHARD TAYLOR, PRINTER, SHOE*LANE, LONDON, — . at -- SELTZER WATER. PNHE Mineral Water of Seltzer in Germany has long been celebrated 4 for its medicinal properties; and it is well known that the operation of this Water, at the same time that it gives a tone to the digestive organs, s so mild, that in Germany (where it is principally used) it forms one of he luxuries which is found at the tables of all the wealthy, who drink it, sither in its natural state, or with wine and pounded sugar. _ The Artificial Seltzer Water now prepared in this country by Dr. STRUVE of Dresden, to the perfecting of which he has paid an unre. mitting attention for several years, possesses in its minutest analysis, as well as operation on the stomach, all the properties of that taken imme- diately from the natural spring. Sold retail by the Confectioners and Chemists in London ; and whole- sale at Dr. Struve’s Mineral Water Agency, No. 23, Bucklersbury, London. - CATON ON DEBILITY, ILLUSTRATED WITH CASES: _' This day was published, price 3s. 6d., a New Edition of PRACTICAL OBSERVATIONS on the DEBILITIES, natural . and contracted, of the GENERATIVE ORGANS of both Sexes;. in- cluding Remarks on Onanism, Seminal Weakness, Nocturnal Emission, Gleet, Tabes Dorsalis, Fluor Albus, &c, with the Theory of Generation, By T. M. CATON; Surgeon, ; No. 6, Norfolk-street, Strand ; oa Late of the United Hospitals of St. Thomas and Guy. Printed for C. Chapple,59, Pall-mall ; Bowen, 315, Oxford-street ; Callow and Wilson, 16, Princes-street, Soho; or by the Author, as above. a : Where may behad, iat - Caton on the Venereal Disease and its Cohsequences, a New Edition, price 5s. illustrated with Cases: A Practical-Treatise on the Prevention and Cure of the Venereal Disease, exhibiting the character, symptoms, and treatment of the diseases immediately or remotely connected with it; con- taining Observations on Gleet, Stricture, Mucal Discharges, the use of the Caustic and common Bougie, Cutaneous Eruptions, Imaginary Venereal. Diseases, &c. &c. comprising an Elementary Work for Students, and a Guide to the general Reader ; interspersed with select Prescriptions ape plicable to each division of the Disease. ‘ \ ry ENGRAVINGS. ; 5 Vol. LXII. A Plate illustrative of Professor Hare's Communications on Electricity, and on the Self-acting Blowpipe.—A Plate illustrative f Mr. Brunev’s new Mode. of Tunnelling, and of his Proposal for a oadway under the Thames.—A Plate illustrative of M. BecquEret’s ixperiments on the Development of Electricity by Pressure.—A Plate. | lustrative of Mr. Bartow’s Experiments on Mr. Marsn’s Thermo- lectric Apparatus.—A Plate illustrative of Mr. SEAWARD’s Observa- ions on Suspension Chain Bridges, rae Pe Vol, LXIII, A Plate illustrative of Mr. Gompertz’s Method of de- _ ——E——.) zauge.—A Plate illustrative of Mr. RicHaArp Taytor’s Paper on the Ay er Marine Formation in the Cliffs near Cromer.—A Plate Illustrative _ ‘Dr. Watcuner’s Examination of a new Mineral named Hyalosiderite ; nd of Mr. Barty’s and M. Fravennorer’s Accounts of the Circular crometer —A Plate illustrative of Professor Hare's Single-leaf Elec- ometer and improved Deflagrators.—A Plate containing two new Spe- es of Ascidia 3 and Amphiuma means, a new Batrachian Animal. ‘i ‘ - b . - F ; nding Ships and Fortifications; and a Cut of Mr Seawarp's Pressure ee “termine the Velocity with which Sound is trafismitted in the Atmo- =? | Vo 1.63. Se _ Philos M Contents oF , Newmer 514. hs ar tees ae Account of some wigpdrinehs ide in order’ to des. sphere. By OLINTHUS. Grecory, LL.D., Associate Acad. Dijon,”