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Whe ECL a He Satin DD gat 6 a Danke, tak A 4% . : A : ; Lt Ce ee Me Oe ‘ 'o4 ve vA i 4 14 Ce Re ey eS se ee bees 7 ba F . ‘ Cryer ad ta Fic ee Oe Be US OT ae) coe sete ie cole see ‘ +) 48 Pee ae ee ee ee bn eek deertt id ao wa kit bnth dade Use detbiikigti-nenin e+ “ bas 5 ‘ ‘ : wid cad Pes eae Seb gb Wa ohare do sie boy awent on re Che Leech hae el ' ‘ \ ve vel Nahe et pte rarer ere a are Merge Ser Mere UE Ree wre See ore oie pent reacts prisemiess ‘yu trae ee rT ‘ phey Poa ate siithiae a Oe el Pf Pec re eo eee Vries CUO Se fa ee ee rie) ee ' 1 Cet ey gw Suuet pee don ear trac fee pn ot Soe ae kar One eV ey Sere | be ue eee any aes Cree eee manne | Doe ir ero em ed Wray er ae ee ee Career eee ee reer i aes ste Veruee wae ‘ “ 14 dues Past how baie BO ha ee Re te ebiid H dit bob ibsted aa MW vies Lae ts W tet a ts aCe RCC ern Wr ene ey eee ee oe re es Tag Bi) ae fer ko’ a ee es : CUP bmw kA * 4 bebe bed aes PN es po one ar inne com te Hr) ‘ 4 fae er e ‘try 4 Vien wh A de Abd ga shee A Ve ee ee ee ew fa tia) Tee Reren ee) tad Settee dena tee ot Fj ebeyte Lt4sa bbe bia edtaho hues tay WhO coe be iy a ee eas Oo! kd ee be fermiiee) Abi gh k bathe Ca nccrct ‘ ee boos oe vas ie aL ea A | coh egy tn wah ROC RL Mein ad ¢ » 4 te oye 1 A bw Mate eid oehas ht Aesata Wed PAs he a) TC 2 are Merced ec Ree a Le a) san 1 ‘ sf ahh 14a ' i JisSener sss ab ket ded TA Vn dg bat AR AMIE TG @ bwenede bb 254 SAE opr ariegeetded reed wtdabrd @rdras (cw : ioe ear marie dos ey via of vie ba ied gies a Carradine Ne ec eS Wr We Sache ce Pe tw be eee area mer vt Saud hype Coe i ae ‘ ue Pr eee eee cece Me ee ee eee) bo het 8-8 ws 0 as oan) eee a . Pantene TC ae Rey a ELA a Sarda tol at naw Phooey beet . Pe ed Be ee a OR nd deal Fahd thin bgt are hye Phenol (oer ect al eee? wy Tce tre Nec cere We ier caer a rr ort ’ ‘ $i Sp 0h Fe Lagat ts rarer OCC i Re ee eee arene nO Men Peer BPP ST ec eT Ay bases Oh , I-45 i ; Fats Ga e ee eae ea iaed ae Wha (led Sere a aebitadheree a Feb Ave ea webeb- apa ‘ via 7 5 oe ‘ sty yy Meh a alhet oui tee & Hebe chtogp POO anna sans + bee ‘ ere ae . : Ce ee eee CRC RE Dt UL ae 0 @ een bob bab Pa he ‘ ‘ ve ‘eh ote m ack if coh Kk aya ee Obi hi eke & Pima ar Tyree Pee A MTS Erte T time & igen cI Let el aN un} i tal! 5 pany ya Ratt wy Harney ANE Wa THE SCIENTIFIC PROCEEDINGS 3 OF THE ROYAL DUBLIN SOCIETY. dew Series. WG AQ) WILD) 2. DUBLIN: PUBLISHED BY THE ROYAL DUBLIN SOCIETY. LONDON: WILLIAMS & NORGATE. 1903-1905. [AKO Tire Sociery desires it to be understood that it is not answerable for any opinion, representation of facts, or train of reasoning that may appear in this Volume of its Proceedings. The Authors of the several Memoirs are alone responsible for their contents. Printed at Tut: University Press, DudbZzx. 90%. Fis ClOMN NT ENG Se VOL. X. PART I. I.—An Improved Polarizing Vertical Illuminator. By J. Joty, M.A., D.Sc., F.R.S., Professor of Geology and Mineralogy, Trinity College, Dublin; Hon. Sec. Royal Dublin Society, : II.—How to introduce Order into the Relations between British Weights and Measures. By G. Jounstone Sronry, M.A., Sc.D., F.R.S. (Plate I.), : : : , ; : 3 : ; 5 I1I.—Photographs of Spark-Spectra from the Large Rowland Spectro- meter in the Royal University of Ireland. ‘Part II.: The Ultra- Violet Spark-Spectrum of Ruthenium. By W. B. ADENRY, D.Sc., A.R.C.Sc.1., Curator and Examiner in cy in the pore! University of Treland, IV.—The Cohesion Theory of the Ascent of Sap: A Reply. By Henry H. Drxon, 8c.D., Assistant to the Professor of Been, Pails College, Dublin, f V.—The Petrological Examination of Paving-Sets. PartI. By J. Jory, B.A.1., Sc.D., F.R.S., F.G.S., Professor of Geology and Minera- logy i in the Univer sity ‘of Dublin; Hon. Sec. oye Dublin SG (Plates II.—V.), : VI.—On an Irish Specimen Dopplerite. By Ricxarp J. Moss, F.I.C., ise VII.—Tyloses in the Bracken Fern (Pleris aquilina, Linn.). By T. Jounson, D.Sc., F.L.S., Professor of Botany in the Royal Galllans of Science, and Keeper of tne Botanical Collections, National Museum, Dublin. (Plate VI.), ; : : : ‘VIII.—A New Method of Erde Tension in Biapids: ny Yo “Ah Jackson, M.A., . ‘ : { IX.—A Transpiration Model. By Henry H. Dixon, 8c.D., Assistant to the Professor of Botany, University of Dublin, : X.—The Leyinge Herbarium. By T. Jounson, D.Sc., F.L.S., Pro- fessor of Botany in the Royal College of Science, and Keeper of the Botanical Collections, National Museum, Denali and Miss M. C. Knows, . : : : : } : : : : PAGE 48 93 101 114 122 1V Contents. PART II. XI.—Floating Refracting Telescope. By Str Howarp Gruss, F.R.S., Vice-President, Royal Dublin Society. (Plates VII.-IX.), XII.—Registration of Star-transits by Photography. By Srr Howarp Gruppe, F.R.S., Vice-President, Royal Dublin Society, XIII.—A New Form of Dipleidoscope. By Sir Howarp Grurs, F.R.S., Vice-President, Royal Dublin Society. (Plate XI.), : XIV.—A Circumferentor. By Srr Howarp Gruss, F.R.S., Vice- President, Royal Dublin Society. (Plate XI.), a : XVy.—A New Form of Position-finder for adaptation to Ships’ Com- passes. By Sir Howarp Gruss, F.R.S., Vice-President, Royal Dublin Society. (Plate XII.), : : ; : XVI.—An Improved Simple Form of Potometer. By G. H. Peruysripee, REID, IIS, o : ‘ : B 5 XVII.—Willow Canker: Physalospora (Botryospheria) gregaria, Sacc. By T. Jounson, D.Sc., F.L.S., Professor of Botany in the Royal College of Science, and Keeper of the Botanical Collections, National Museum, Dublin. (Plates XIII.—XV.), XVIII.—The Comparison of Capacities in Electrical Work: an Application of Radio-active Substances. By J. A. McCuetnanp, M.A., Professor of Experimental Physics, University College, Dublin, XIX.—Preliminary Note on the Action of the Radiations from Radium Bromide on some Organisms. By Henry H. Dixon, D.Sc., Assistant to the Professor of Botany, University of Dublin; and J. T. WicHam, M.D., Assistant to the Lecturer in Pathology in Trinity College, Dublin. (Plates XVI.—XVIII.), XX.—An Experiment on the Possible Effect of High Pressure on the Radio-activity of Radium. By W. E. Witson, D.Sc., F.R.S., XXI.—On the Reactivity of the sya Todides. ey F. G. Donnan, M.A., Pu.D., : : 6 : XXII.—On the Structure of Water-jets, and the effect of Sound thereon. By Puitre E. Betas, Science Scholar, Department of Agri- culture and Technical Instruction for Treland, Royal College of Science, Dublin. (Plates XIX.-XXII.), : XXIII.—Remarks on the Cases of Carbon Monoxide Asphyxiation that have occurred in Dublin since the addition of Carburetted Water-gas to the Ordinary Coal-gas.. By E. J. McWexeney, M.A., M.D., D.P.H., M.R.I.A.; Professor of Pathology at the Catholic University Medical School; Pathologist to the Mater Misericordiz Hospital, Dublin, ; 3 d ‘ XXIV.—Photographs of Spark-Spectra from the Large Rowland Spec- trometer in the Royal University of Ireland. Part III.: The Ultra-Violet Spark-spectra of Platinum and Chromium. By W. E. Aprnry, D.Sc., A.R.C.Sc.1., Curator and Examiner in Chemistry in the Royal University of Ireland, : : XXV.—The Pre-glacial Raised Beach of the South Coast of Ireland. By WEEE: “WRIGHT, B.A., and H. B. Me) B.A., F.G.8. (Plates XXIII.-XXXI. ih : : ¢ PAGE 133 138 141 148 146 149 167 178 « 198 195 203 217 235 Contents. XXVI.—Vapour Pressure Apparatus. By Jamus J. Hutcuinson, XXVII.—Formation of Sand-ripples. By J. Jory, B.A.I., D.Sc., F.R.S., _ F.G.S., Professor of ee teey and Mineralogy in in the University of Dublin, XXVIII.—On a Method in Qualitative Analysis for Determining the presence of certain Metallic Oxides. By Cuarizs R. C. Pee IMAC, IWias, 12el INECHSL, Gwes, : : : Fann: PART III. XXIX.—Tho Temperature of Healthy Dairy Cattle. By G. H. Wootpriper, M.R.C.V.S., Professor of lise, Heyat Sere College of Treland, XXX.—-On the Petrological Examination of Road Metal. By J. Jory, ID SGb5 ale . Professor of Geology and eee in the University of Dublin. (Plate XXXII.), . XXXI.—On the Construction of Fume-Chambers with Effective Ventilation. By Water Nort Hartiey, D.Sc., F.R.S. (Plate XXXIIL), XXXITI.—On the Structure of Water-jets, and the effect of Sound thereon. Part Il. By Puitie E. Betas, A.R.C.Sc.I. With Note on Combination-Tones, By Professor W. ,F. Barrert, F.R.S. (Plate XXXITV.), : : : : : : : : XXXIII.—Notes on the Constitution of Nitric Acid: and its ae By Water Nort Haxtiny, D.Sc., F.R.S., : : XXXIV—On Floating Breakwaters. By J. Jory, Sc.D., F.R.S., Professor of Geology and Mineralogy in the University of Dublin, Hon. Sec. Royal Dublin Society. (Plates XXXV., XXXVI.), INDEX, 330 340 351 360 373 378 385 DATES OF THE PUBLICATION OF THE SEVERAL PARTS OF THIS VOLUME. Part 1.—Containing pages 1 to 132. (December, 1903.) Mae OF of ,, 133 to 334. (November, 1904.) oy ee a ,,- 385 to 383. (July, 1905.) ERRATUM. For page 280 (preceding page 283) read 282. pn A oe on gn THE SCIENTIFIC PROCEEDINGS OF THE ROYAL DUBLIN SOCIETY. Vol, X. (N.8.) DECEMBER, 1903. Part 1. CONTENTS. I.—An Improved Polarizing Vertical Illuminator. By J. Jory, M.A., D.Sc., F.R.S., Professor of Geology and Mineralogy, Trinity College, Dublin ; Hon. Sec. Royal Dublin Society, . 1 II. —How to mtroduce Order into the Relations between British Weights and Measures. By G. Jonnetone Stonzy, M.A., Sc.D., F.R.S, (Plate T.), . 6 III.—Photographs of Spark- “Spectra from the Large Rowland Spectro- meter in the Royal University of Ireland. Part II.: The Ultra-Violet Spark-Spectrum of Ruthenium. By. W. E. Aprengy, D.Sc., A.R.C.Sc.1., Curator and Examiner in Chemistry in the Royal University of Ireland, : 24 IV.—The Cohesion Theory ot the Ascent of Sap: A Reply. By HENRY H. Drxon, Sc.D., Assistant to the Professor of Botany, nee College, Dublin, : : 48 V.—tThe Petrological Examination of Paying- Sets. Part I. By J. JOLY, B.A. I., Sc.D., F.R.S., F.G.S., Professor of Geology and Mineralogy i in the University of Dublin ; Hon. Sec. neyo PAGE Dublin Society. (Plates II.—YV.), . 62 VI.—On an Irish Specimen of penne By RIcHARD J. Moss, F. Tr G., F.C.S., 93 VII.—Tyloses in the Bracken Fern. (Pteris aguilina, Linn.). By T. Jounson, D.Sc., F.L.S., Professor of Botany in the Royal College of Science, ‘and Keeper of the Botanical poections; National Museum, Dublin. (Plate VI.), ; 101 VIII.—A New Method of. producing Tension in Liquids. By ey T. Jackson, M.A., . 3 : : : ; ; ; . 104 ITX.—A Transpiration Model. By Henry H. Dixon, Sc.D. ieee to the Professor of Botany, University of Dublin, : 114 X.—The Leyinge Herbarium. By T. Jounson, D.Sc., F.L. 8., Pro- fessor of Botany in the Royal College of Science, ‘and Keeper of the Botanical Collections, National Museum, Dublin; and Miss M. C. Knowies, . : : ; : : 4 elle | The Authors alone are responsible for all opinions expressed in their Communications, DUBLIN: \ PUBLISHED BY THE ROYAL DUBLIN SOGIETY. WILLIAMS AND NORGATE, ™ ; y, 14, HENRIETTA-STREET, COVENT GARDEN, LONDON;-—— 6 is ay 20, SOUTH FREDERICK-STREET, EDINBURGH; aay anp 7, BROAD-STREET, OXFORD. 1903. Price Four Shillings and Sixpence. Royal Dublin Society, FOUNDED, A.D. 1731. INCORPORATED, 1749. OOOO OOOO EVENING SCIENTIFIC MEETINGS. Tur Evening Scientific Meetings of the Society and of the associated bodies (the Royal Geological Society of Ireland and the Dublin Scientific Club) are held on Wednesday Evenings, at 8 o’clock, during the Session. Authors desiring to read Papers before any of the Sections of the Society are requested to forward their Communications to the Registrar of the Royal Dublin Society at deast ten days prior to each Evening Meeting, as no Paper can be set down for reading until examined and approved by the Science Committee. The copyright of Papers read becomes the property of the Society, and such as are considered suitable for the purpose will be printed with the least possible delay. Authors are requested to hand in their MS. and necessary Illustrations in a complete form, and ready for transmission to the Editor. THE SCIENTIFIC PROCEEDINGS OF THE ROYAL DUBLIN SOCIETY. I. AN IMPROVED POLARIZING VERTICAL ILLUMINATOR. By J. JOLY, M.A., D.Sc., F.R.S., Professor of Geology and Mineralogy, Trinity College, Dublin; Hon. Sec. Royal Dublin Society. [Read DecumBer 16, 1902; Received for Publication January 1 ; Published Marcu 9, 1903]. In the Scientific Proceedings of this Society, vol. 1. (N. s.), p. 485, et seq., 1 have described a method of observing on an ordinary rock-section the interference tints proper to double the thick- ness of the section, and thereby producing discriminative effects not possible to obtain in the ordinary mode of observation. I may recall that the method consists in placing a plane reflecting surface (polished speculum metal, preferably) beneath the rock-section as it rests on the stage of the microscope, and transmitting, by means of any vertical illuminator (as used for examination of metals, &c.), a plane polarized ray vertically downwards through the rock-section. The ray reflected from the speculum metal is again returned through the object-glass, and, alter passing through the analyser, shows to the eye the retarda- tion proper to double the thickness of section. In this manner the range of colour-variation from one species to another is greatly increased: in fact, what differences exist for the single thickness are now doubled in amount. In the different arrangements proposed to effect this, one objec- tion, in some degree, applied in all cases: a want of verticality in SCIENT. PROC. R.D.S., VOL. X., PART I. B 2 Scientific Proceedings, Royal Dublin Society. the downward directed ray which involved necessarily that the section and its image in the reflector did not accurately overlie one another. In rocks of fairly coarse grain this did not signify ; but, in those of finer grain, an unpleasant overlapping of the colours of adjacent crystals occurred in the plane of incidence and reflection. In all the forms of the apparatus described, there was also required a separate polarizer to polarize the beam entering the illuminator. Recently it occurred to me to try the effect of a simple vertical illuminator which I saw described in Messrs. Watson’s Catalogue, consisting of a single small cover-glass contained within a collar to be inserted just above the object-glass. The cover-glass is to be inclined so that rays entering an aperture in the front of the collar are, in part, reflected by the cover-glass (which can be rotated on a horizontal axis into the suitable inclination), and thence pass downward through the object-glass and illuminate the opaque object being examined. The rays finally reaching the eye (return- ing through the object-glass much the way they came) are for the most part transmitted through the transparent reflector. In this arrangement the illumination is evidently vertical ; and, the parallax in the plane of incidence and reflection involved with the use of prisms or opaque reflectors should be absent. I did indeed suggest such a mode of getting out of the difficulty in my former paper, but had not then given it trial. On applying one of these very simple and inexpensive illumi- nators to the purpose described, I found that its use was in every way satisfactory. The quantity of light transmitted is sufficient even without the use of a lens to strengthen the beam. As an artificial source, a mantle-burner is excellent, and shows colour well. There is no appreciable parallax; and even small microlithic felspars in basalts may be seen, each glowing with its own colour and with sharp margins. From the first I noted the added advantage that, with this mode of illumination, the use of a polarizer is unnecessary. Hvyen using a horizontal beam and the glass at 45° to axis of microscope, the polarization of the ray reflected from the uncovered speculum metal is very complete, as may be seen by examination with a double- image prism, or more simply by rotating the analyser. But when the source of light is elevated above the horizontal level of the Joty—An Improved Polarizing Vertical Illuminator. 3 aperture in the illuminator, so that the ray more nearly reaches the glass at the polarizing angle, the polarization is still more complete. As manufactured, the aperture is not placed so that the | | | | l A I ROTTER iS SARE Te WLLL. R polarizing angle can be actually attained. It should be located a little above the axis of the reflector. The accompanying diagram shows the proper angles for mirror and ray when it is desired to obtain the ray as nearly unmixed with ordinary light as possible. 4 Scientific Proceedings, Royal Dublin Society. The cover-glass reflector should be inclined 333 degrees with the optical axis of the microscope. In the figure the illuminator is lettered J. The cover-glass, C, reflecting the light, is shown at 33° with the vertical axis of the microscope. This insures that the ray falling vertically through the object-glass is at the polarizing angle (57° nearly) with the glass reflector. It would be convenient if this angle was marked by the makers on the rotating head commanding the reflector. Or the correct position for the source of light (if artificial) may be found by arranging it to be 25 units of length above the plane of the aperture and 76 units distant. This gives a beam reaching the reflector at the proper angle ; and it only remains to rotate the reflector till the eye, looking through the microscope, perceives the speculum reflector illuminated. The larger part of the entering beam passes through the cover-glass, and is absorbed in the blackened walls of the illumi- nator. The reflected part is plane polarized, the vibration being executed parallel to the plane of the mirror. Descending, it passes first through the slip carrying the rock-section, it being advisable to invert the slip from its usual position, placing it. face downwards, so as to bring the section nearer the speculum reflector. Then passing through the section, it meets the reflector of speculum metal (/) ; and is returned by it through the section, and so back to the cover-glass C. The greater part of the beam again passes through, reaching the eye, some part being returned to the source of light. What passes through is almost unmixed plane polarized light. A lens placed in front of the aperture may be used to intensify the illumination. It has the effect of diluting with ordinary light the polarized beam somewhat, as rays from it are converging, and therefore do not all strike the glass at the polarizing angle. The loss of intensity of coloration is but trifling, and does not diminish the value of the arrangement as a means of diagnosis. The usefulness of the reflector & is increased if it is perforated (I think preferably excentrically) with a conical hole, so that the upper edge is as sharp as possible. This hole should be blackened on the inside. The use of it is obvious. A small crystal can be examined simultaneously by the reflected ray and by light transmitted from the polarizer beneath the stage: the crystal Joty—An Improved Polarizing Vertical Illuminator. 5 being so placed that one part of it extends over the aperture. In making this comparison it is well to stop off sufficient of the trans-— mitted substage light to make the twice transmitted and singly transmitted rays about equally bright. The result is a valuable discriminative test, as will be realized more especially by any one acquainted with the work of MM. Lévy and Lacroix, “ Les Minéraux des Roches,” to which I have more fully referred in my former paper. | It will be seen from the above that in order to use the method of examination by double transmission, the reflecting plate of specu- lum metal (a small dise about 3 ems. in diameter is a convenient size) and the vertical illuminator as described are alone required. It is worthy of notice that this mode of obtaining the effects of a doubled thickness of the section by no means involves a doubled opacity ; for“inclusions, flaws, &c., lie above their own images, and fresh ones are not added, ‘as would be the case in a section of actually double the thickness. SCIEN. PROC. R.D.S., VOL. X., PART I. C [RROR GN Il. HOW TO INTRODUCE ORDER INTO THE RELATIONS BETWEEN BRITISH WEIGHTS AND MEASURES. By G. JOHNSTONE STONEY, M.A., Sc.D., F.B.S. (Pxate I.) [Read Frpruary 17; Received for Publication, Fupruary 17; Published May 2, 1903.] Tue weights and measures that may lawfully be used in the United Kingdom are :— 1. The Imperial system of weights and measures, for all commodities. 2. Metric weights and measures, for all commodities. 3, Apothecaries’ weights and measures, for drugs when sold by retail. 4, The ounce Troy and its decimal subdivisions, for bullion and precious stones. 5. Coin weights, for coins. This is a complete list of British weights and measures, as the law at present stands. In the time of Edward II., the British inch was defined as the length of three barley-corns, round and dry, taken from the middle of the ear, and placed end to end. The foot and yard were derived from the inch as determined in this way. In the time of Henry VII. a standard yard was made, and the foot and inch were derived from it. This was an immense improvement upon the earlier practice. Another yard, supposed to be a copy of Henry VII.’s standard, took its place as the English standard yard in the time of Queen Elizabeth. In1742 a brass yard was constructed by Graham for the Royal Society, which was derived from the yard-measure of Queen Elizabeth; and a copy of Graham’s yard was made by Bird, the optician, in 1760, which Parliament adopted as the British standard yard. It continued the standard until 1834. Our present standard was made in Sronsy—How to simplify British Weights and Measures. 7 1855, and represents the best attempt that it was found practicable to make, to recover the exact length of Bird’s yard previous to the damage which it sustained in 1834. Similar meritorious efforts were made from time to time to introduce the greatest accuracy which the state of knowledge at each period permitted’ into our standards of weight and capacity, which, in earlier times, had been somewhat uncertain measures ; until they have ultimately become those excellent standards which are now in the custody of the Board of Trade. The imperial system of weights and measures was legally intro- duced into the United Kingdom by the Weights and Measures Act of 1824, from which date imperial standards were substituted for Winchester standards which had lasted from 1588 till 1824. The imperial system was subsequently modified and brought into its present form in 1836, by the substitution of the avoirdupois pound of 7000 grains, divided into 16 smaller ounces, for the troy pound of 5760 grains divided into its 12 larger ounces. The avoirdupois pound had, at various times, been divided into 15, or into 16, or into 20 ounces. The standards legalised in 1824 were under the charge of the ‘Clerk of the House of Commons, when the great conflagration took place on October 16, 1834, which destroyed the Houses of Parliament, and in which the British standards were either lost or so damaged that they were no longer available as standards. The present writer, when between eight and nine years of age, was an eye-witness of this great fire, and under circumstances which caused it to make a lasting impression on his memory. A few years later he reached an age when he could take notice of what was going on about him in the world; and he then followed with special interest the successive steps by which it was sought to restore our standards; and also the efforts that were being made by some of those who understood the subject, to obtain for Englishmen the lasting advantages of a system of weights and measures that had not grown up haphazard, but in which the measures of length, of surface, of capacity, and the weights, are 1 An interesting account of these successive advances will be found in “Our Weights and Measures,’’ by H. J. Chaney, Esq., Superintendent of the Weights and Measures Department of the Board of Trade. C2 8 Scientific Proceedings, Royal Dublin Society. brought into the most convenient relations to one another, and all of them brought into relation with the system of numeration which all men employ. This was sought in two ways—one party, including most of those who were competent to judge in the matter, endeavoured to introduce into England the metric system, not because the metre is approximately the ten-millionth part of the Harth’s quadrant, but because the metric system presents in the greatest attainable degree the above-mentioned permanent advantages. The other party—a minority among those competent to judge—followed Sir John Herschel in his desire that Great Britain should set up a new system in competition with the metric system, in which the unit of length, which he proposed to call the module, should be the ten-millionth of the Harth’s polar axis, and should be divided decimally. This module would be very nearly 50 British inches ;. and he proposed that the inch should be very slightly lengthened to make this relation exact. ‘There would then be exactly 100 of the new half-inches in his module. He also proposed that the half-pint should be given a distinctive name, and that its capacity should be altered in the very slight degree which would suffice to make the new half-pint exactly the hundredth part of the new cubic foot. A similar slight change was to be made in the ounce: to make the new ounce exactly the weight of the tenth part of the new half-pint of water. He pointed out that to bring all this about would demand only excessively small deviations from our existing inch, pint, and ounce; and he thought that if England set up a decimal system based on these units, it would be at once adopted by the United States which employs English measures, and by Russia which at that time had a system of measures derived from the English; and that it would thus come into use in the greater part of the manufacturing industry and of the commerce of the world. A popular account of his proposal was given by Sir John Herschel in a lecture delivered in 1863: one of his “Familiar Lectures on Scientific Subjects,” published in 1867. Herschel’s advice was that his new decimal system should be sanctioned by Parliament; while at the same time permitting the continued use of the old multiples into feet, yards, pounds, gallons, ete., in their present relations to the inch, ounce, and pint, but with the slightly altered values consequent upon the Stonryv—How to simplify British Weights and Measures. 9 small changes in the latter which he recommended, and which he made the foundation of the rational and decimal system which he suggested for adoption in England. If this option were allowed, he anticipated that the better system would gradually supersede the less perfect; and that thus a good, if not the best, system of weights and measures would become established in this country without demanding any appreciable sacrifice from the people, or enforcing upon them any sudden change of their habits. This proposal was made forty years ago, and since then the world has not stood still. The use of metric measures, which up to forty years ago had advanced slowly, has made more and more rapid progress every decade since that time; and has now an assured footing among all the more civilized populations of the world, except those who speak English—not excepting the people of Russia, whose measures, forty years ago, were based upon those of England. And, on the other hand, the considerations in favour of Sir John Herschel’s proposal have become weaker. It is now perceived that far greater accuracy can be attained by comparing all other measures with the standards established by the Inter- national Committee on Weights and Measures, in which our Government has taken part, than by any attempted comparison with the length of the Earth’s axis, to which Sir John Herschel attached so much importance, or with the length of the Harth’s meridian as was laboriously attempted by the founders of the metric system; or by pendulum determinations, as had also been advocated. It must also be recognised that the measures of length, of surface, of capacity, and of weight, are brought into better relation to one another in the metric system than in Sir John Herschel’s; and that this gives the metric system an advantage over its competitor of primary importance, and one the benefit of which will last for all SUR time within any nation that - uses metric measures. Tt is useless to speculate how Sir John Herschel, if he were writing in 1903 instead of in 1863, would deal with the question. For my part, I do not think that he, or any other man who is as competent to judge as he was, and who examines fully into the question as it presents itself in the twentieth century, could continue to advocate England’s striving to set up the Herschel 10 Scientific Proceedings, Royal Dublin Society. system of measures in competition with the metric system; or could entertain the least idea that it would ever become a universal system, employed by the whole civilized world, such as the metric system will become if it is adopted by the English-speaking populations of the world. Nor can we come to any other con- clusion than that thisis fortunate; since of the two systems, the metric system is distinctly the better for the whole future of the world, on account of the more useful relations established in it between measures of length on the one hand, and the weights and measures of surface and of capacity on the other. There is another considerable practical advantage whiclt attaches to metric measures of length, to which the attention of the present writer was called, nearly fifty years ago, by the late Dr. Humphrey Lloyd, Provost of Trinity College, Dublin. It depends on the magnitude of the millimetre, which is the smallest division placed on the metric rules used by artisans. The milli- metre, though small, is so conspicuous to the eye on such rules that the workman measures, with extreme ease, to the nearest millimetre when making very rough measurements. Thisisa better measure- ment than is usually made in rough work with workmen’s English rules. And the millimetre is also nearly the smallest interval that can be correctly subdivided into tenths by estimation. When one uses metric scales much, one insensibly acquires the power of dividing any length into tenths by estimation, with a remarkable approach to accuracy. This useful power, when once acquired, makes it possible for a workman, using a metric scale, to measure lengths to the nearest tenth of a millimetre, rapidly, with the naked eye, and without verniers. This is much greater precision than can be attained with the rules commonly employed by workmen in this country. The tenth of a millimetre is nearly the smallest interval that the unassisted eye can see. It is about the average thickness of sheets of paper. What then is our present position in England in regard to weights and measures, and what are our prospects ? An Act was passed in 1864 which purported to make it lawful to use metric weights and measures in the United Kingdom; but it was held by our courts of law that it did not attain its object, because it did not recite and repeal a clause of a preceding Act which forbade the use of any other than imperial measures in Stronsey—AHow to simplify British Weights and Measures. 11 buying and selling, and because it made no provision for the verification of metric measures by the Board of Trade. The Weights and Measures Act of 1878 made a very halting advance. It provides for the verification of metric weights and measures and sanctions their use for other purposes, but forbids their being used in buying or selling commodities. This Act left matters in such a state that, though metric measures might lawfully be used by scientific chemists, and have been universally used by them, the pharmaceutical chemist who had to sell his medicines was compelled by the law to continue to use the old bad Apothecaries’ weights and measures. So matters remained until 1896, when the Government at length introduced a Bill permitting the use of metric measures for all purposes. ‘To this Bill, as to the Acts of 1864 and 1878, were attached, unnecessarily complex tables of equivalents for the conversion of imperial into metric measures, and of metric into imperial ; and when the attention of the Government was called to this, they omitted the tables from the Bill, and introduced a clause authorising the issue of tables by Order in Council. In 1897 the Bill passed in this amended form; and simpler tables have since been issued by an Order in Council, dated 19th May, 1898. These are now the tables of equivalents which have legal force. After this legislation had passed, Mr. Balfour, the leader of the House, and Mr. Ritchie, who was then at the Board of Trade, expressed the opinion, in replying to deputations, that Parliament had now done its part, and that it was for the English people to make the next move. The deputations had asked the Government to introduce a Bill, forbidding the use of any other than metric measures after two years. I venture to submit that both the request and the reply need revision and amendment. The contention that it is the nation who should make the next move is not tenable. Parliament has not as yet done anything to facilitate the use of metric measures. It has made it barely pos- sible for an Englishman to do so. After forty years of legislation it has only gone so far as to relieve an Englishman who uses them from being punished for doing so; and it is plain to common sense that this is not enough. As matters now stand, with the intricate and troublesome relations which Parliament has allowed to subsist between the two systems of measurement, it is in vain to ask men 12 Scientific Proceedings, Royal Dublin Society. engaged in the active employments of life, and trying to earn money, to use those measures which they judge to be best, merely because they will not henceforth be fined for doing so, but where Parliament has lefé matters in such disorder that they will imeur Joss in other ways. ‘The disorder is at present such that work begun in shops using imperial measures cannot be finished in shops using metric measures, or vice versa, without involving both expense and trouble. Neither has Parliament, as yet, put it within the power of the English tradesman to make the change. How can a beginning be made ? How can a prudent tradesman use other measures than those in which his customers are accus- tomed to think? He could indeed make the necessary beginning if a yard was only another name for nine decimetres, which is the proposal made in this paper, and if a pound was another name for 43 hektograms; but he cannot start using metric measures so long as a yard is nine decimetres and a complicated fraction, and a pound 43 hektograms and another troublesome fraction. It is the start that is impossible. He cannot begin using them as matters at present stand. It is therefore plain that Parliament has not done enough; and legislation, like other things, if it falls short of being sufficient, is a failure. If there is no further legislation, Englishmen may continue for another century com- pelled by the force of circumstances to put up with inferior weights and measures, and so far without the same advantages, both within this kingdom and in the competition of the world, as the Frenchman the German or the Belgian. Why should not we, as well as they, have every attainable advantage—every ad- vantage that Parliament can procure for us and for our children— and which I venture to submit it is the duty of Parliament to place practically within our reach ? The deputations that waited on the Government proposed fur- ther legislation, but legislation so drastic that it is doubtful whether Englishmen would submit to it. For my part, I hope, on wider grounds, that Englishmen would resent any approach to being dragooned, and I think the proposal a very injudicious one. Englishmen, as compared with the nations of the Continent, are fortunately more difficult to drive, while, also fortunately, they are easier to lead where the reason for a change can he made plain; and moreover it must be remembered that English- Stonry—How to simplify British Weights and Measures. 18 men are less prepared for a sudden change from one set of measures to another, than were the populations of continental countries, of whom a large proportion live sufficiently near frontiers that are mere imaginary lines, to grow up in familiarity both with their own way of measuring, and that employed by their neighbours over the border. On the other hand, our people know no other system than one, and at present cannot think in any other. This, I submit, ought to be fully recognised by Parliament in framing any legislation that is to be imposed upon the United Kingdom. The same want of preparedness for any abrupt change prevails throughout our British Colonies, and among the people of the United States, whose interests, in addition to those of our colonies, I think we are bound to try and promote, since they have hitherto used British measures. None of these nations —neither our daughter nations, nor the people of the United States, nor ourselves—are as prepared for acquiescing in change, as were the peoples of the continent of EHurope. And to this may be added the fact, that,in many continental countries, it was found expedient to make such modifications of local measures as made it possible to allow them to continue in use along with the metric measures. All these considerations, and many others, point to that way of dealing with the task before Parliament, which I have endeavoured to work out in the proposed Draft Bill, which will be found in the appendix. The legislation which is there suggested is not any half-way house. It will accomplish the whole of what is required, and no further intervention by Parlia- ment will be necessary. The proposal aims at establishing sufficiently simple relations in place of the present needlessly complex relations between imperial and metric measures; and, at the same time, it leaves undisturbed the mutual relations between the different parts of the imperial system, to which the people of this country are accus- tomed. It thus seeks to make the change as little obtrusive as it can possibly be made, and as little likely to be felt as change by the bulk of the people; while at the same time it is effectual, inasmuch as it puts it within the power of any member of the community, without incurring loss, to use either metric or imperial measures whichever he finds most convenient : and under these circumstances the spread of metric measures is assured. 14 Scientific Proceedings, Royal Dublin Society. It will also make the teaching of weights and measures to children both easier and more instructive. A yard, to the children of the future, will simply be another name for nine-tenths of a metre; an imperial gallon will be nine-tenths of the metric gallon, or half dekalitre ; a pound avoirdupois will be nine-tenths of the metric pound, or half kilogram ; an acre will be presented to them by their teachers as a special name for the size of a strip of ground forty metres wide and 100 long; a mile, to them, will be another name for 1,600 metres; and so on. ‘These relations to metric measures will then take the place of our present confusing tables of weights and measures. They will be easier remembered, con- vey more meaning, and dispense with a task which is at present one of the most irksome in school education. As to the metric tables, to which the imperial measures will be in the foregoing way annexed, they teach themselves: they need no elaborate learning. Another further advantage is that, if these simple relations between imperial and metric measures are called into existence by Parliament, our posterity, reading books written now or heretofore, will find nothing in them that is unintelligible—descriptions of distances in miles, of heights in feet, of weights in pounds or tons, will be understood by them and will convey substantially the same meaning to them then as they do to us now. It is perhaps the greatest merit of this proposal that the less educated part of our population will not be sensibly affected by it. To take the fifth of an inch off each foot, and half a quarter of an ounce off each pound, will leave those measures so like what they are at present, that the difference will scarcely be perceived, and will not be felt after the change has once been made. Even the price lists prepared under the present system need not be changed. They may continue in use: everything will be adjusted by allow- ing a discount of one penny in five shillings off the list price of goods sold by the foot or yard, and a discount of one penny off every half-guinea of the price of goods sold by the pound—or the adjustment can be made in another way, by adding an inch to every two yards in measuring lengths, and by adding an ounce to every eight pounds in weighing. ‘These are not too serious burdens for Parliament to lay even upon our illiterate classes, in order to bestow upon Englishmen at large and upon all our posterity the great boon that is contemplated. StonEY—How to simplify British Weights and Measures. 15 As regards other classes of the community, the author has earefully gone into details in reference to each large class— merchants, tradesmen, manufacturers, mechanical engineers, civil engineers, artisans, country gentlemen, farmers, and others—and has ascertained that they will not be inconvenienced except to a slight extent and for a short time; while the proposal, if carried into effect, will secure permanent advantages to them and to their posterity out of all proportion to the inconvenience. It would too much lengthen this paper to attempt to go into these details. Instead of doing so, I may refer to the opinion recently expressed in public by Sir Andrew Noble, Bart., whose judgment in this matter should carry the greatest weight both with Parliament and the country, since it is based upon his prolonged and unrivalled experience as Head of the vast engineering works of Armstrong and Co., unsurpassed in England as regards both the variety and extent of their operations; and since itis the deliberate restatement of a judgment which he has now held for two and a half years. Speaking in the discussion upon weights and measures, which recently occupied two meetings of the Institution of Electrical Engineers, Sir Andrew Noble publicly recommended the pro- posal put forward in the present paper, and reiterated an opinion, which he had communicated to me two years and a half ago, when my proposal was first made. His judgment was at that time expressed in the following words, which he allows me to publish :— “The Metric System is bound to become the system of the world ; and it is difficult to conceive any scheme by which English measures can be brought into relation with the Metric System with less inconvenience to the public than that which you have arranged in your proposed Bill.” In Plate I. will be found a diagram of the present two-foot rule, and of the rule which will take its place if the proposal now made is carried out. The diagram shows that the foot and inch will look very much like what they have hitherto been; and it also shows into what very convenient relation with metric measures they will be brought. Even less change than that exhibited in the diagram suffices in most other parts of the proposal. 16 Scientific Proceedings, Royal Dublin Society. : APPENDIX. DRAFT OF A BILL TO SIMPLIFY THE RELATIONS BETWEEN BRITISH WEHIGHTS AND MEASURES. Submitted by G. Jounstons Stoney, M.A., Sc.D., F.R.S. Wuereas it is lawful to use either imperial or metric weights and measures within the United Kingdom of Great Britain and Ireland for the purpose of determining the quantities of commodities to be bought and sold; And whereas it is expedient to simplify the relations in which the weights and measures stand to one another, that may lawfully be so used ; Be it therefore enacted that on and after the first day of January, 190—, the imperial weights and measures shall cease to be derived from the standard yard and standard pound deposited with the Board of Trade, and shall on and after the aforesaid date be derived from the iridio-platinum linear standard metre and iridio-platinum standard kilogram deposited with the Board of Trade and numbered 16 and 18 respectively : in the manner set forth in Schedule A attached to this Bill, which shall be read as part of this Bill; in which are set forth the various weights and measures of the imperial system which, with their multiples and aliquot parts, may lawfully be used after the said first day of January, 190—; and in which are also set forth their equivalents in metric measure, and the ratios which may lawfully be used in comparing the imperial weights and measures at present in use, which are hereinafter called the old imperial weights and measures, with those that will take their place under the provisions of this Bill, which are hereinafter called the new imperial weights and measures. In Schedule B attached to this Bill and which shall be read as part of this Bill, are set forth the metric weights and measures which with their multiples and aliquot parts may also lawfully be used in determining the quantities of commodities to be bought or sold, and their equivalents in the new imperial measures. Sronry— How to simplify British Weights and Measures. 17 Schedule A. NEW IMPERIAL WEIGHTS AND MEASURES, WITH THEIR METRIC EQUIVALENTS. I.—MEASURES OF LENGTH. SEctTIon 1. The mile shall continue to be divided into 8 furlongs, the furiong into 10 chains, and the chain into 4 poles or perches. These measures shall have the following values : New mile, . = 1600 metres. New furlong, . = 200 metres. New chain, = 20 metres. New pole, or perch, . = 5 metres. It shall be lawful to regard the ratio of each of the new measures in this section, to the old measure of the same name, as being the ratio of 100 to 100-58, or as being the ratio of 172 to 173. Section 2. The yard shall continue to be divided into 3 feet, and the foot into 12 inches. These measures shall have the following values :— 9 decimetres. 3 decimetres. 25 millimetres. New yard,. . . New foot, . New inch, . i Il It shall be lawful to regard the ratio of each of the new measures in this section, to the old measure of the same name, as being the ratio of 100 to 101-6, or as being the ratio of 625 to 633. The new imperial yard is nine-tenths of the metric yard or metre. II.—LAND MEASURES. SECTION 3. The acre shall continue to be divided into 4 roods, and the rood into 40 square perches. These measures shall have the following values :— Newacre, . .. . . = 4 dekares. Wenrn@al 5 56 6 6 o = il Glen New square perch, . . = 4 of anare, or 25 square metres. It shall be lawful to regard the ratio of each of the new measures in this section, to the old measures of the same name, as being the ratio of 100 to 101°17, or as being the ratio of 85°3 to 86°3. 18 Scientific Proceedings, Royat Dublin Society. I1I].—AVOIRDUPOIS WEIGHTS. SEcTION 4. The ton shall continue to be divided into 20 hundredweights, the hundredweight into 4 quarters, and the quarters into 2 stones. These weights shall have the following values :— 1000 kilograms. Newton, .. . New hundredweight,. = 50 kilograms. New quarter, - = 123 kilograms. New stone, . . . . = 6; ulograms. It shall be lawful to regard the ratio of each of the new weights in this section, to the old: weight of the same name, as being the ratio of 100 to 101°6, or as being the ratio of 623 to 633. SEcTION 5. The avoirdupois pound shall continue to be divided into 16 avoirdupois ounces, and the avoirdupois ounce into 16 avoirdupois drams. The pound may also be divided into 9 half-hektograms. These weights shall have the following values :— New avoirdupois pound, = 43 hektograms. New avoirdupois ounce, = 28% grammes. The new avoirdupois dram shall be one-sixteenth part of the new ounce. It shall be lawful to regard the ratio of each of the new weights of this section, to the old weight of the same name, as being the ratio of 100 to 100°8, or as being the ratio of 125 to 126. The new avoirdupois pound is nine-tenths of the metric pound or half-kilogram. TV.—MEASURES OF CAPACITY. SECTION 6. The quarter shall continue to be divided into 8 bushels, the bushel into 4 pecks, the peck into 2 gallons, the gallon into 4 quarts, the quart into 2 pints, and the pint into 4 gills. These measures shall have the following values :— INGMY CMERI, 6 5 5 6 6 SS MS Ihara. New bushel, ... . . . = 86 litres. INewapecket Wey wer waite ae 9 litres. INewr gall, 5 6 «1 6 o = 43 litres. INOW QU, 6c 4 6 5 = 13 litre. The new pint shall be half the new quart. The new gill shall be a quarter of the new pint. Tt shall be lawful to regard the ratio of each of the new measures in this section, to the old measure of the same name, as being the ratio of 100 to 101-02, or as being ithe ratio of 98 to 99. The new imperial gallon is nine-tenths of the metric-gallon or half-dekalitre. Stroney—How to simplify British Weights and Measures. 19 V.—SPECIAL WEIGHTS AND MEASURES. Section 7.—Troy WEIGHTS. | The Troy ounce shall continue to be divided into 20 pennyweights, and the pennyweight into 24 grains. These weights shall have the following values:— New Troy ounce, . New pennyweight, New grain, . 62 grammes. 16 gramme. one 15‘ of a gramme. ou dl It shall be lawful to regard the ratio of each of the new weights of this section, to the old weight of the same name, as being a ratio of 100 to 97-2, or as being the ratio of 35°7 to 34-7. —_—— Section 8.—Corn WEIGHTS. It shall continue to be lawful to use coin weights of the same amounts as may lawfully be used at the time of the passing of this Bill. Schedule B. METRIC WEIGHTS AND MEASURES,* WITH THEIR EQUIVALENTS IN NEW IMPERIAL MEASURE. I.—MEASURES OF LENGTH. METRIC. New IMPERIAL. Stage, or myriametre, . . = 10 kilometres, = 61 miles. Kilem, or kilometre, . = 1000 metres, = 5 furlongs. hektome, or hektometre, = 100 metres, = 65 chains. dekam, or dekametre, - 10 metres, = 2 perches or poles. IMiCtiCMEt et eY EO ee tees de Gl ony St Ue eee AOL inches: decimetre, . - vo ofa metre, = 4 inches. Cengimetres-me yey ae = Tsp Of ametre, = “45 of an inch. Millimetre, . zoo of ametre, = sts of an inch. fecoaeiel of a metre, Micron, . ll ' ol * Hiverything that is possible should be done to get the names of metric measures to be henceforth so pronounced by English-speaking people, as to become good English names. ‘To bring this about it is advisable to discourage the prevalent mistake of pronouncing kilo (which in English corresponds to Milo), as if spelled killo in such words as kilometre, kilogram, kilowatt; and of pronouncing litre (which should rhyme with mitre) as if it had been leetre. See note 2 on page 21. 20 Scientific Proceedings, Royal Dublin Society. II.—LAND MEASURE. METRIC. New IMPERIAL. Hektare, . . . . . = squareof 100 metres, = 2% acres. dekare,. . - . . - = 10 ares, = 1 rood. Are,. . .. - . - = squareof10metres, = 4 square perches. | III.—WEIGHTS. METRIc. New AVOIRDUPOIS. ROMs ihe fas ives ue! Sets = 1000 kilos, = 1 ton. quintogram, or quintal, . . = 100 kilos, = 2 hundredweights. quartogram, or myriagram,. = 10 kilos, = + hundredweight. Kilo, or kilogram,. . - . = 1000 grammes, = 2 pounds. metric pound, or half-kilogram,= 500 grammes, = 15 avoirdupois pound. hekto, or hektogram,. . . = 100 grammes, = 4% pound. dek, or dekagram,. - . - = 10 grammes, = 5 pound. Gaamme sy okie tee ee oo — te at oa = 15 grains. GOGH, 6 6 6 5 5 0 = yo gramme, = 14 grain. Centiorani, ws se ido gramme, = zo grain. Milligram, . . . .- -+- = £xouo gramme, = gp grain. IV.—MEASURES OF CAPACITY. METRIC. NeEw IMPERIAL, Stere, kilolite, or kilolitre, . = 1000 litres, = 1114 pecks. hektolite, or hektolitre, . . = 100 litres, = 119 pecks. dekalite, or dekalitre, . . = 10 litres, = 13 peck. metric gallon or half-dekalitre, = 5 litres, = 1} imperial gallon. STAWBHERY WC BO Pict G3 Mot We? «rat ET Mme ned abut sha 2 gallon, or § quart. decilitre,. . . -.- -..-. = =i; litre, = zs gallon. centilitre, . . 5. . +. = zoo Litre, = zo gallon Millite, or millilitre, . . . = obo litre. = zoo gallon. In measuring commodities for purchase or sale, it shall be lawful to treat the follow- ing measures as equivalent :— 1 stere, and one cubic metre; 1 hektolitre, and 100 cubic decimetres ; 1 dekalitre, and 10 cubic decimetres ; 1 litre, and 1 cubic decimetre ; 1 decilitre, and 100 cubic centimetres ; 1 centilitre, and 10 cubic centimetres ; 1 millilitre, and 1 cubic centimetre. Norr.—The stere differs very little from the cubic metre, the litre differs very little from the cubic decimetre, and the millilitre differs very little from the cubic centimetre ; the ratio of the stere to the cubic metre, or of the litre to the cubic decimetre, or of the millilitre to the cubic centimetre, being approximately the ratio of 100°016 to 100, or of 6251 to 6250. End of draft Bill. Sronry—AHow to simplify British Weights and Measures. 21 Norte 1. On Graduating Scales, and Making Screws. By a recent International arrangement, in which our Board of Trade took part, the following relation between the yard and the metre has been definitively agreed upon, viz. :— Old yard == 0:9148992 metre. This in practice is undistinguishable from 0:9144 metre, since the proportional increase which is here made is but a small fraction of the probable error in such determinations ; asis manifest upon comparing with one another the values furnished by the best determinations that have been made in Europe and America. Another consideration concurs in showing that the difference (which is less than the millionth part of the whole length) has no practical significance. It is the amount by which the length and subdivisions of a bronze rule are altered when the temperature deviates by less than 33; of a degree Centigrade from that for which the rule was justified. Now the intended temperature of the original bronze standard, which was destroyed in the conflagration of the Houses of Parliament in 1834, and of which our present imperial standards are meant to be copies, is not known to th’s degree of accuracy; inasmuch as there exists no record of the kind of glass used in making the stems and bulbs of the mercury thermometers, by which the temperature prescribed by the Act of 1824, viz.: 62° F., was determined, when those copies were made from which our present standards are taken. Adopting then the simpler value, we find that— 0-9 metre (the new yard): 0:9144 metre (the old yard) ::125: 127, from which ratio we gain the following very valuable practical rule, that Dividing Engines and Lathes which are furnished with Whitworth screws the pitch of which is known in old imperial measure, can be made to graduate scales and make screws of equal accuracy im the new invperial measure, or in metric measure, by the simple expedient of introducing two change-wheels, one with 125 the other with 127 teeth. Nore 2. On the Pronunciation of the Names of Metric Weights and Measures. The word litre, like mitre and nitre, has come into English, through the French from the Greek; and in Greek the spelling and SCIENT. PROC. R.D.8., VOL. X., PART I. D 22 Scientific Proceedings, Royal Dublin Society. accentuation of the three words are alike. They should therefore be pronounced in the same way in English; both on this account, and still more in order not to infringe an almost universal rule that when the first syllable of an English dissyllable ends in i, the i is to be pro- nounced as it is in biped, cider, dial, final, giant, &c. To justify the pronunciation of the word litre which is now prevalent, it would need to be spelled lietre or leetre; and, as its etymology forbids this, it is the pronunciation which should be corrected. Again, in xAuds and all its Greek derivatives, the « of the first syllable is long. It is advisable therefore to pronounce the ilong in its English derivatives, to avoid introducing a needless anomaly into our language. This concerns the words kilem or kilometre, kilo or kilogram, kilolite or kilolitre, and kilowatt; in all of which the i should be pronounced as it is in microscope, nitrogen, &c. Huphony (which is really ease of pronunciation) in no degree requires us to keep up the practice of frenchifying the terms litre, kilometre, &c., especially in the objectionable form of pronouncing the first syllable as French and the other syllable or syllables as English. The practice has lost whatever semblance of appropriateness it may have had while Metric Weights and Measures were exclusively foreigen. But in other cases euphony does justify a deviation from what would otherwise be required for etymological correctness, as when hekto is employed in the metric nomenclature as the prefix to signify a hundred. Hekato would be awkward in such words as hektogram, hektolitre, &&. So, again, kilo is excusable instead of kilio as the prefix for a thousand ; and perhaps the spelling—k instead of ch-—as being on the whole more convenient. Are, the metric unit of land surface, and the group of letters a-r-e in the words hektare and dekare, should in English be pronounced as in the words declare, dare, &c. Norte 3. On Alternative Names. Shorter names for some of the metric measures will inevitably arise among English-speaking people who use those measures. It is therefore advisable that they be contrived with care, so as to secure :— 1. That they shall embody in briefer form the whole of the mean- ~ ing conveyed by the longer names ; Proc. R.D oc. R.D.S,N.S,,Vol. x Plate 1. Ey by iy ly) A # lay ; iy The Olay two toot soe nano Y Mare Peeeeetee fli vl tr eS) eect ry yu ren ae ts fu {000 of 1 he West. Newr man ith Stonsy—Hovw to simplify British Weights and Measures. 23 9. That they shall be so unlike in sound, as not to be easily mistaken for one another. [One valid objection to the existing practice of mispronouncing the word litre, is that when mispronounced it sounds too much like metre. This liability to error does not occur in France, since in French métre and litre have different vowel sounds: it was by frenchifying English that the confusion was introduced.] 3. That they shall be so related to the longer names as naturally to suggest them. Keeping these ends in view the following alternative names are proposed, in which the letter i in the syllables ki and li is meant to be pronounced as in mile. Kilem or kilometre. Kilo or kilogram. Hektome or hektometre. Hekto or hektogram. Dekam or dekametre. Dek or dekagram. Kilolite or kilolitre. Hektolite or hektolitre. Dekalite or dekalitre. Millite or Millilitre. These names are recommended; but if not approved, a pen may he drawn through them where they occur in the Draft Bill. Norn 4. Convenient Identity of Relationship. Tf metric measures are established in England under the proposed legislation, the following identity of relationship will in future years be found in an unusual degree convenient to persons reading books written before the change :— nine-tenths of the metre. q nine-tenths of the metric-gallon, or half-dekalitre. nine-tenths of the metric-pound, or half-kilogram. nine-tenths of a litre per are, or of a hektolitre per hektare. These are the yard, gallon, pound, bushel, and acre of the ‘new’ system, and differ by inconspicuous amounts from the yard gallon pound bushel and acre referred to by the books in question. 30, Leprury-Roap, Lonpon, W. February, 19038. The imperial yard The imperial gallon, The avoirdupois pound, A bushel per acre, I uu Enea, fl JONG PHOTOGRAPHS OF SPARK-SPECTRA FROM THE LARGE ROWLAND SPECTROMETER IN THE ROYAL UNIVER- SITY OF IRELAND. PART IL.!: THE ULTRA-VIOLET SPARK-SPECTRUM OF RUTHENIUM. By W. EH. ADENEY, D.Sc., A. R.C. Sc. I., Curator and Examiner in Chemistry in the Royal University of Ireland. [Read January 20; Received for Publication January 23; Published Aveust 7, 1903. ] Repropuctrions of photographs of the spark-spectra of the plati- num and other metals from the 21:5 ft. Rowland spectrometer in the Royal University, Dublin, have already been published in the Scientific Transactions of this Society, vol. 7, 1901. Scales of approximate wave-lengths were ruled on the nega- tives from which the reproductions were prepared; and it was at first hoped that, with their aid, it. would be possible to easily identify the spectral lines with those previously given in various tables of wave-lengths for the same metals, and that consequently it would not be necessary to exactly measure the lines. More recent work, however—more especially that on tire effect of pressure upon the wave-length of lines in the electric are,” and on displacement of the spark-lines analogous to those in the are*— has rendered it advisable to accurately measure all the lines on the photographs. _ The measurements of the spectrum which forms the subject of this communication, have been made by means of a light microscope mounted ou a stage which can be moved through a space of about one inch long by a short micrometer screw. Hach line has been measured at least twice, and many of them three and four times. _ Kayser’s values‘ for the well-defined lines in the arc-spectrum 1 For Part I. see Trans. R.D.S., Vol. viz., 1901, p. 331. 2 Humphreys and Mohler, Astrophysical Journal, 1896, 1897. 3 ii. Haschek, Spectroscopic Studies, Astrophysical Journal, 1901. 4 Kayser, Konigl. Preuss. Akademie der Wissenchaften zu Berlin, 1897. ApENEY— Photographs of Spark-Spectra. 25 of the same metal have been employed as standards for calculating the wave-lengths from the micrometer measurements. In the cases where the calculated wave-lengths have shown a close agreement with those by Kayser, the latter observer’s values have been adopted. In those cases in which they have not agreed, they have been confirmed or corrected by remeasuring the lines with the same microscope and micrometer, but with the addition of a finely divided glass-scale in the eye-piece, and a photograph of a réseau belonging to the observatory of Cambridge University, for which the author is indebted to Mr. Arthur R. Hinks, m.a.! With this arrangement, it has been possible to measure a number of neighbouring lines relatively to one another with considerable accuracy. In the appended list of wave-lengths,* Kayser’s have been given for convenience in indicating those lines which are common to both forms of the spectrum and those which only appear to belong. to one or other form. In the author’s photograph of the ruthenium spectrum, 1461 lines have been measured between the two extreme limits of wave- length 2263 and 4560; and Kayser has given 1613 lines as occur- ring in the are-spectrum between the same limits of wave-length. About 800 lines are common to both forms of the spectrum. Besides these, about 800 lines occur in Kayser’s list, but appa- rently not in the author’s, and about 650 in the author’s and not in Kayser’s. Displacements in some of the spark-lines, as indicated by Haschek in his interesting paper entitled “ Spectroscopic Studies,’’ may account for some of these differences; and such lines may therefore be similar, although slightly differing in wave-length. Some of the wave-lengths in both lists may be affected by unusually large errors, owing to diffuseness in character of the lines, or to faintness or to some distortion in the films, or to some other source of error, and may in reality be coincident. There can, however, be no doubt that a large number of the lines, which appear peculiar to each form of the spectrum, are due to the different modes of producing incandescence employed. 1 See Mr. Hinks’ paper on ‘‘'‘The Cambridge Machine for Measuring Celestial Photographs.’’ Monthly Notices of R. A. S., May, 1900. 2 Note the wave-lengths have been given to two places of decimals only. 26 Scientific Proceedings, Royal Dublin Society. Kayser states, in his paper, that the lines which Rowland gives near the cyanogen band 3883 could not be seen in his photographs owing to the band being very strong in them. Rowland! gives 15 lines in this part of the spectrum (3778 to 3876). Ali these occur in the author’s spark-spectrum, with but one exception (382832). The possibility of some of the lines at least being due to im- purities must be considered. Many of them are, as a matter of fact, coincident with those of other elements, particularly of iron. The author has carefully compared his spark-spectra of ruthenium with those of the rest of the platinum metals, «nd of iron, cobalt, nickel, chromium, manganese, copper, calcium, and silicon. As was anticipated from the very large number of lines in most of these spectra, several cf them were found to have similar wave- lengths to many of the ruthenium lines; but on carefully com- paring the character of these lines with those with which they coincided in the ruthenium spectrum, it was quite easy to see that they were not the same. The author has only been able to identify, in his ruthenium spark-spectrum, 19 lines due to iron, and 2 to calcium. Exner and Haschek’ have measured 2250 lines between the limits above given; some 1330 of these occur in the author’s photographs. The larger number of lines occurring in the photo- graphs of these authors is, no doubt, chiefly owing to the fact that different methods of producing the sparks were employed in the two cases. The author desires, in conclusion, to acknowledge his indebted- ness to Miss M. Hall for the very valuable assistance she has given him in the work of making the micrometer measurements and of ealculating the wave-lengths from them. 1 Astrophysical Journal, 1896. 2 Sitzungsberichte der Kais. Akad. der Wiss. in Wien., 1896. Apvrnry— Photographs of Spark-Spectra. RUTHENIUM.- KAYSER. ADENEY. Qt 2330°05 38°09 40°77 92-50 2263-73 68-26 82-00 87-28 98-80 2303-06 04:97 05°85 13°51 20-82 29-11 31:23 31°81 32°26 33°72 34-05 35°05 36°93 38:05 40-00 40°77 41-11 42°66 42-99 46°45 50°51 51°23 52-92 57-99 58-90 59°14 62°47 64:13 67°31 70°25 72:08 75-71 76°30 79°54 79°94 82°08 83°53 87°28 91°73 93°84 94°70 KAYSER. ADENEY. 2396°79 2402-80 08-00 08°74 20°91 29-67 2395°66 Jomo 97-70 98-63 99°28 2400°38 01-18 01°93 02°80 05°00 06-12 06°67 07°37 08-00 08-d1 10°24 11°62 13°32 13°60 14-00 14:93 15°30 15°82 16°64 17-05 19:04 20°24 22°30 92-91 24°56 26°66 26°96 27°26 27°82 28°98 30°45 31:00 32°25 33°81 34°98 39°03 39°72 41-05 41-42 41-82 28 Scientific Proceedings, Royal Dublin Society. KAYSER. ADENEY. KAYSER. ADENEY. 2443°48 2490-56 2444°13 2491-10 44°50 91°85 91°85 44°92 94°12 94-00 45°52 45-52 94°22 47-54 94°77 94°77 48-96 48-96 95°76 95°88 50°46 50°46 97°14 50°65 50°90 98-51 51°27 98°67 98-67 53°85 99-87 99-60 54°27 54°27 2500-45 2500°36 59°01 00°94 55°61 55°61 01°57 56°52 66°89 01-99 02°12 56°67 02°48 02°48 57°31 57-31 02-97 68°71 03°40 59°15 59°15 05°13 60°17 05°73 60°57 06-18 61°51 06°61 62°20 07-09 07-18 63°03 63°03 08°38 64°47 08°51 08-81 64°78 64:78 09-16 67°67 67-67 09°71 69°78 10°24 70°61 70°61 11-06 70°81 11°68 11°41 71°58 12-90 12°79 12°22 72°22 13°42 13°42 72°81 14°10 73°55 15°37 74:12 15°74 74°51 74:55 16°25 75°48 16°88 76°40 17:00 76°96 17-40 17-40 7-22 17-73 78°33 18-60 18-60 79°01 79°01 19°49 79°46 20°04 79°61 20°93 20°89 80°83 21-08 81°22 81-22 21-70 81°83 22°41 82°63 22°83 83°82 24°95 24°95 84:06 84-06 25°12 84°66 25°26 86°31 25°73 25°68 87°26 26°01 88°58 26°91 89°34 27°19 90-02 28°03 28-03 ApEenEY— Photographs of Spark-Spectra. KAYSER. ADENEY. KAYSER. ADENEY. 2528°81 2560-35 2560°35 29°81 2529°81 60°92 30°40 62°25 30°67 62°58 82°18 63°00 83°30 33°38 j 63°38 33°66 63°78 34°23 64°02 30°15 85°16 64°50 80°42 64.67 64°73 30°80 65°28 36°32 65°77 36°51 66°30 36°90 66°67 66°67 37°18 67°98 37°78 37°78 68°85 38°57 68-93 39°82 39°82 69°84 69°84 40°41 *40-41 70°18 41-38 71-07 42°24 71:17 42-60 72°37 43°24 72°51 43°30 -43°35 72°71 43-78 73°09 44°32 44°32 73°65 73°65 45-10 74:20 46°87 46-01 75°34 46-77 46°81 76°17 47-60 47°80 7711 Cgoul 5 48-86 78°65 78°65 49-26 49-26 79°07 79°10 49-58 79°31 49-66 79°62 49-92 79°88 79°94 50°95 80-08 51°47 80°32 80°32 51°82 51°82 80°88 52°08 52°08 81°23 81°23 52°38 81-99 52°52 82°48 52°97 83°13 83°13 53°58 84°21 54-06 85°41 54°79 85°82 55°73 ; 86°16 86-16 55°96 55:96 86-95 66°10 56°10 87-41 56°99 56°84 88-08 57°25 89-13 57°78 57°78 89°65 89°65 58°13 89-89 58°36 91-09 58°63 58°63 91-20 91-20 58°91 91-44 59°50 59°60 91°71 30 Scientific Proceedings, Royal Dublin Society. KAYSER. ADENEY. | KAYSER. ADENEY. 2592-09 2624:87 2593-79 2625-17 94°65 25°59 94-93 . 25°95 95°73 26-29 96-04 96-04 26°44 97°42 97°49 26-60 97-84 27°74 27°74 98-07 27°90 98-68 98-68 28-38 28-38 98-99 (Fe) 28-62 28-91 99-53 (Fe) 29°49 2600-00 30-01 2600-84 30°31 30-19 01-39 31-22 01-55 01°55 31-66 02°49 32°21 03-00 32°58 03°43 32°85 04-41 04-41 33°54 05°44 33-93 05-95 35°45 35°39 06-40 35°93 35°93 07°18 (Fe) 36°62 36°62 07-44 36°76 08-02 08-02 36°95 09-14 09°14 38-60 38-60 09°57 09°57 39°21 10-18 39-67 11-13 40-41 40-41 11°63 41°55 41°72 11-99 49-06 49-06 12°17 12°17 42°61 12°63 43-04 43-04 12:99 43°60 43-60 13-14 44-71 44-71 13-37 46-09 46-09 14-15 14°15 46°72 14:67 14:93 47°39 15°18 15°18 48-02 16°50 48°54 17-29 48-71 17°88 48°87 48-87 18-68 50-08 19-11 50°21 19-42 50°49 50-49 19°75 50-69 20-15 20°15 50-97 50°97 20°71 20°71 51°37 51°37 21-17 51-60 21-46 51-94 51:94 21-91 52-24 52-05 23°51 53-05 23°76 53-24 23°91 53°78 94°35 54-01 Avrnry—Dhotographs of Spark-Spectra. 3l eee a KAYSER. ADENEY. KAYSER. ADENEY. 2654-56 : 9685°57 54:90 2654:90 85°94 69°19 2686°38 86°38 55:29 | s 86°94 56°33 56°33 87°21 87-21 56°64 87°58 87°58 56-78 88-22 88:22 67°26 57:25 88:67 58°28 88:97 88-97 68°48 89°al 58°86 90°49 90°49 59°64 90:90 60°67 | 91-20?92-20 61°25 61:25 92-20 61:69 61°69 93°39 93:39 61:94 93°75 93°75 62°36 94-25 62°94 94-85 63°85 96°65 64°65 97°18 64°83 64°83 97:-6C 65°23 98:16 65°54 65°54 98:23 65:80 98:80 67:48 67:48 99-42 67°89 99:96 68°04 ; 2700-32 68:42 2700°58 68°71 00:77 00°77 69°24 01:09 70°60 01°43 70°81 02:92 ; 02°92 72°45 72°45 03°22 73°09 73°09 03°40 73°55 03°89 73°69 04°31 73°93 04:65 74:27 74-27 04:99 75:27 05°42 75°58 07°41 76°27 08-05 76°43 08:93 76°86 09-16 77-06 09-29 09-29 77°41 09°85 17:97 10°32 10°32 78°27 78:27 12°17 78°84 78°84 12°49 12-49 79°54 12:97 79°84 13°27 13°14 80°66 13°82 13°66 82°84 15°33 83°76 15:60 84°17 16°15 84°54 84°69 16°23 89°24 85°24 17:10 32 Scientific Proceedings, Royal Dublin Society. KAYSER. ADENEY. KAYS#R. ADENEY. 2717-51 717-51 2752°14 17-93 2752°55 52°55 18-92 18-92 52:87 52°87 19-61 19-61 53-54 53-54 19-84 19-84 55-30 21-65 55:80 (Fe) 21-94 56°46 29-49 57-18 22-76 22-76 57-91 22-90 58-10 58°10 23-10 59°35 24-95 60-27 60-27 25°55 25°55 60-88 27-06 27-06 61-60 27°74 62°17 29-04 62°40 29-54 29°54 63°23 30°12 63°51 63°51 30-42 30-42 64-01 30°79 64-82 31:03 65°24 31-48 65°53 65°53 32:01 66-00 32-83 66-32 33°17 66-66 33°68 67-66 34-44 34:44 68-03 35-81 35°81 69-02 69-02 36-41 36°54 69-99 36°92 36-92 70-40 70°40 37-66 70°81 37°87 71:15 38-98 71°59 39°31 39-40 71:99 39-68 (Fe) 72-55 40-09 72°72 72°72 40°33 73-07 49°15 74-25 43-57 74-59 44-02 44-02 75-29 44-54 44-54 75°72 75-72 44-82 76-01 45-29 77-63 77°63 45-34 78-54 45-90 79-08 79-08 46°17 46°17 79°54 46-62 80-86 80°86 46-75 82°31 82°31 46-99 47-00 83°85 47-62 84-62 84-62 48-03 84:98 49-26 85:29 49-66 85°75 49-92 85:90 50°45 86°50 51:70 87°35 ApgnEyY— Photographs of Spark-Spectra. KAYSER. ADENEY. | KAYSER. ADENEY. 2787-98 2787-93 2826-36 88°84 26-81 89°72 89°72 27°19 90-28 2827-63 27°63 90-70 27:97 27°97 91-16 91-16 29-25 29-25 92-42 92-42 30-82 92°75 31-28 94-42 32-00 95-46 95°46 32°76 96-10 33°64 96°65 96°65 33°97 97-20 34-11 97°91 34°52 98-91 35°77 99°71 36°25 2800-03 36-68 36°68 2800-24 37°38 37-28 00°79 00°79 38°73 38°73 02°26 02°26 39-16 02-91 02°91 39°52 03-59 40°66 40-66 03°76 41-23 04-94 41-78 41-78 06°85 06-85 42°65 07°34 42-86 07°70 43-28 08-34 44-86 10°13 10°13 45-30 10°65 10°65 46-43 10°79 10°79 46°66 11-36 47-25 11-66 47-72 12-06 49-40 49-40 12-93 49-73 13-44 50-86 13°81 13°81 51°23 1518 53°28 15°41 53-43 53-43 17°19 54°17 54°17 17°74 54°47 18-46 18°46 54°82 18-91 55°01 19-06 55°45 55°45 19-67 56-00 21-28 56°15 21-50 21°50 56-67 22°14 57°37 67°37 22°37 57-77 22-66 22-66 57-88 22°91 58-69 23°33 59°65 24-00 60°11 60°11 24-87 60°49 25-20 60°95 25-62 61-17 393 34 Scientific Proceedings, Royal Dublin Society. KAYSER. ADENEY. KAYSER. ADENEY. 2861-51 2861-54 2900°63 61°83 2901-89 01-74 62°96 62°96 02°22 02°22 63°11 02:97 63°33 03°18 64-73 04°83 65°65 05°76 05°76 66-19 05°95 66-41 06°42 06°42 66°74 66°74 08°59 67-20 09°35 09°35 68-29 10-10 68°48 68°43 10°54 68°66 12°48 12°45 69-05 69°05 12°56 12°56 70°32 12°87 70°53 18°29 13°29 71°30 14°10 71°57 14°43 71°76 15°74 73°34 16°30 16°47 73°83 17°25 74°16 17°35 75°10 75°10 17°88 17°88 77°20 18-76 17°93 78°04 19-28 79°20 19°73 19°73 79°47 20°37 79°85 21°07 21:07 80-24 21°28 80°64 80°64 21:95 81-37 81°37 22°50 82°22 82°22 23°40 82°70 24°20 83°70 83°70 24°76 84°60 84-60 25°19 85°60 25°69 86°64 86°64 25°89 25°89 87°22 87°22 26°69 88-11 88-11 26°91 88°74 27°23 89°54 89°54 27°89 27°73 90°54 28°27 91-24 91°24 28°61 28°61 91-76 29-03 29-03 92-00 29°87 92°65 92-65 31°35 93°84 93°84 33°37 33°37 95°55 84°30 95°93 34°64 96°64 35°67 97°82 97°82 36°13 98°40 36°38 98°65 06°59 98-8) 37°20 99°82 99°70 37°45 Aprnry—Photographs of Spark-Spectra. KAYSER. ADENEY. KAYSER. ADENEY. 2937-68 2974-10 39-25 2939°25 74:45 2974°45 39°80 74:79 40-06 75°25 40-47 76°71 76°71 42°37 42°37 77:05 4282 77°35 77°35 43°59 43°59 77°60 77-60 44-04 44-04 78°76 78-76 44-299 79°85 79°85 45-20 80:07 80:07 45°59 81-08 81-08 45-78 45°78 82-05 82:05 46°67 83°74 47:10 47°10 85:08 47°72 85°78 48°47 86-10 49-61 49°61 86°45 86°45 50°08 50:08 88-05 50°65 88-22 51°52 89-08 89-06 52°36 89°45 52°60 ; 89°77 52°78 90°41 54°37 54:20 91-71 54°59 54:59 92-08 92-08 55°46 92°48 55°71 93°07 55°96 93°39 57°30 94°54 58-12 95:08. 95:08 58-99 96:01 59°86 59-86 96-44 60°35 96°89 61:10 97°34 61-60 97°74 97°74 62-08 98:09 62°44 98°45 98-45 62°71 99-01 99-01 63°52 63°52 3000:00 63°83 3000-34 64:42 00°57 65°29 65°29 01°76 01:76 65°67 65°67 : 02-19 65°82 02°60 02°60 66°67 04:71 66:98 06-09 67°46 06°71 06-71 68°23 68-11 08:00 68°56 68-56 08°37 69°07 69-07 08°70 69°S5 69°85 08:91 71°10 09-80 09-80 72°59 72°59 10°62 10°62 73°08 12-00 73°74 73°74 13°04 36 Scientific Proceedings, Royal Dublin Society. KAYSER. ADENEY. KAYSER. ADENEY. 3013°17 3050°31 13°48 50°50 14°31 51°70 3015-60 51°97 16°10 52°45 16°82 53°48 17°36 17°36 55°04 805504 18°16 18°16 56°88 18°32 56:97 56°97 19°47 57:47 19°88 19°88 58°76 08°76 20°36 58°91 20°99 20°99 59°28 59-28 22°72 60°37 60°37 23°05 60°67 24-00 62°16 62°16 25°21 64°96 64°96 27:20 27-20 66°61 27°36 67-71 27:68 68°36 68°36 27°91 27°91 69°29 28°79 71°59 29-04 71°72 30°80 71°82 30°89 72°42 32°03 73°44 73°50 32°77 32°77 75°41 75°41 33°16 76°89 33°56 33°06 17:18 17:18 34:17 84°17 77°66 35°58 78°21 35°93 79°27 36°58 36°58 79°95 37°85 37°85 80:29 38°08 81-01 81:01 38°29 81°22 38°85 81:49 81°49 39°59 81:95 81-95 40:07 40:07 83°25 40°42 40°42 84°63 42°03 84°73 42°60 42-60 85°60 49-95 42-95 86-18 86-18 43°16 86°63 86°63 44-08 87°04 45°63 88°05 45°83 45°83 88°18 88°18 46°11 88°36 46:36 46°36 89°25 89°25 47-11 89°92 89°92 47-88 90°34 90°34 48°44 90°54 48-61 48°61 91-00 48-90 48-90 91:97 91-97 49-17 §2-09 49°32 92°35 ApENEY—Photographs of Spark-Spectra. oy eee ADENEY. | KAYSER. KAYSER. ADENEY. 3093-01 3129-72 3094-50 94-64 29-94 95-64 30-71 96-06 32:12 96-67 96-67 32:99 3132-99 97°71 97°71 33-51 98-05 33-80 98-95 34-90 34-90 99°39 99°39 35°17 3100-05 35-48 3100-95 00:95 36-04 36-04 01:59 36°45 02°50 36-66 36:66 03°51 37-04 04:07 38-88 04:57 39°38 05:38 05-38 39°65 05°52 41-08 41-08 05-91 41-66 06-94 06-94 43°46 07°37 43°76 43-76 07°70 07°70 44-37 44°37 07°83 44-89 08°53 46-18 46-18 10°15 46-47 10-64 10-64 47-32 11-24 47°55 47-55 12-01 12-01 48-14 12°41 48°59 48-59 12°78 12°78 50:28 13-50 50°80 50-80 13°76 13-76 51:25 14°53 51°78 15-54 52:35 16:95 53:93 53:93 17°18 54:54 17-56 55:90 18-17 56-73 18-79 56-92 20°65 57-74 20:90 58°70 29-11 59:00 (Ca) | 59-00% 22:97 60-04 60-04 23°61 60°80 24-28 24-98 63-19 63°30 24-48 24-48 64-94 64-94 24-71 65:09 24-98 65°31 65°31 26-07 66-24 26°15 66°68 26°73 26°73 67-51 67°51 27-39 68-36 27°64 68-65 68-65 28-07 70-20 28°54 71-35 29°57 72°78 72°78 * This line is not due to calcium in spark-spectrum. SCIENT. PROC. R.D.S., VOL. X., PART I. 38 KAYSER. 317322 73°50 74°24 76-40 77°16 78°84 79°38 80°57 81°13 81:31 85°28 85°55 86°16 86°87 88:06 88°46 88°71 89°42 89°84 90-09 91-30 91-90 92°17 93°62 95-14 95:44 96°72 97°60 98°44 99°24 8201°37 01-60 02°70 05°43 07°75 08-41 08°54 08°87 09°76 10°29 13-10 Scientifie Proceedings, Royal Dublin Society. ADENEY. 3174°24 75°32 77°16 79°38 83°54 85:28 86°16 88°46 90-09 92°17 92°52 95°14 95°85 96°72 98°74 3201°37 03°62 04°36 05:08 05°43 06°82 07°40 07°75 KAYSER. 3214°48 15°61 16°64 19°27 20°20 20°90 21-30 21°49 23°39 23°72 24°77 25°42 26°50 27°02 28-02 28°28 28°65 28°85 29°88 30°74 31°87 32°18 32°89 33°65 34°92 00°23 35°43 36°10 38°15 38°67 38°90 39°75 41-36 41-64 41-88 42°28 42°98 43°64 44-48 44-59 44-72 45°78 46-38 47-50 48-98 50:07 50°15 ADENEY. 3213°33 16°64 17-96 19°49 20°20 20°90 21°49 22°07 23°39 24°18 25°03 26°50 27°02 28°65 KAYSER. 3250°61 51°46 52°03 52°40 52°68 53°04 53°14 54°67 54°86 55°17 55°36 56°48 56°75 58°18 59°11 59°81 60°30 60°49 61-26 63°74 63°99 64:69 64°81 66°59 67°27 68°35 69-09 69°34 70°39 T1°75 72°37 73°22 73°77 74:88 76°82 77-70 79°52 80-60 80°68 81°74 82°00 82°74 85:07 85°51 86°04 Apvrenry— Photographs of Spark-Spectra. ADENEY. 3201°10 52°03 53°36 54°67 54°86 56°48 57°94 58°18 59°11 59°81 60°30 60°49 64°81 66°59 67°07 68°35 69°05 69°80 73°22 73°77 74°83 75°87 17-70 80°25 81°26 81°74 83-11 84-46 85:07 86°55 | KAYSER. 8291°25 91°79 94°27 94°93 96°25 96°79 97°39 98°10 98°56 99-48 99:93 33801°73 02°31 04°14 04°42 04°63 04°77 04:95 05:80 06°31 07°68 08-12 08°75 09:97 10°22 11°09 11°39 12°07 12°35 14:20 15°18 15°37 15°59 16°52 17°05 18-01 18°99 19-66 19-94 21°39 21°63 22°37 23°23 24-08 24°51 25°14 ADENEY. 3g 3294°27 96°25 96°79 97°39 98°10 98°56 99°48 3301°35 01°73 01:94 04°14 05°15 06°31 06°81 08:12 08°22 09-00 09°38 09-97 11:09 12°99 14°88 15°37 16°52 17-05 17-66 18-01 18-99 24°51 25°14 89°39 40 KAYSER. 8325°37 27°83 28°58 32°19 32°48 32°77 04°76 30°82 36°30 36°77 37°96 38°85 39°09 39°69 39°93 41-23 41°36 41-81 42°85 43°00 44-67 44-93 45°45 46°36 47°75 48°15 48°83 49-82 50°24 50°36 50°68 52°06 53°12 53°44 53°78 54°00 55°80 56°33 56°60 58°11 59°23 61°30 62°14 62°46 64°28 64°93 65°16 65°47 67°87 68°05 68°59 69-43 69°81 ADENEY. 3020°3/ 30°82 37°96 39°69 09°93 41°81 42°85 43°32 44°67 45-45 47-78 48-15 49°25 49°82 50°36 03°44 59°28 60°20 61°30 62°46 64°23 KAYSER. 3370°72 71°79 71-99 72°92 74-12 479 75°04 75°38 76°19 78°17 79°40 19°75 80°30 81-04 83°05 85°30 85°61 80°84 86°39 87°37 87-97 88°85 89°25 89°64 91-04 92-03 92°65 95-47 96°06 96°97 98°47 99-04 3400712 00°74 00-89 01°30 01°64 01-88 03°92 05°43 06-02 06°74 07-04 09°42 09°70 IES ff 12°22 12°95 13:87 14°18 Scientific Proceedings, Royal Dublin Society. ADENEY. ee 3870°19 10°72 71°99 72°92 73°45 74°12 14°79 78°17 79°75 80°30 83°75 85°30 85°61 87°97 88°85 89°25 89°64 92-03 92-65 99°04 99°15 3401°64 01°88 a ee Aprnty—Photographs of Spark-Specira. KAYSER. ADENEY. | KAYSER. ADENEY. 3414:°42 3463°29 0463°29 14-79 3414-79 63°75 16°33 16°33 65°44 65°44 16°90 67°19 67°19 17-49 17°49 69°80 17-79 70-20 18-13 18-138 72°39 19-39 19°39 72°84 72°84 20°24 20°24 73°45 20°88 73°90 73°90 22°58 75:00 24°39 77°35 26°12 26-09 79°45 27-72 27-72 80-30 80-30 28°48 28°48 81-04 28°79 28°79 81°47 81-47 29-70 ; 29°70 81-66 80°57 82°50 30°91 30°91 83°32 83°32 82°35 32°35 83°46 83°46 32°56 83°65 32°91 32°91 86°36 30°41 30°41 86°95 34°33 84°33 87°87 34°93 89-90 30°34 30°34 90°30 36°24 90°88 90°88 36°48 92°26 36°89 36°89 93°38 93°38 88°52 38°52 94°41 38°82 96°15 96°15 39°84 96°29 40-36 40°36 98-10 98-10 41-94 99-10 99-10 43°31 3001-06 43°82 01-25 44°57 3501°51 45-46 02°58 02°58 45-68 03-60 46-10 46-10 04°65 46°23 09°35 46-63 09°87 46-96 11-50 49°11 49-11 13°25 49-61 13°81 13°81 51°01 14°65 14°65 53°06 53°06 14°91 53°37 16°05 16°05 55°55 18-00 58°89 19-10 56°77 | 56°77 19-80 19-80 57°05 20°29 20°29 57°85 24°16 59°74 24°62 61°55 27°39 62:21 62°21 28°05 Scientific Proceedings, Royal Dublin Society. 42 KAYSER. ADENEY. 3028 °84 3028°84 29°26 31°55 31°55 32°97 32°97 00°59 35°53 30°99 30°99 36°78 38°10 38°10 39°42 39°42 39°52 41°79 41-79 47°14 47°14 48-70 49-90 50°42 50°42 50°73 54°00 54:00 56°78 56°78 57°20 57°20 60-00 60°85 61°83 62°04 62°04 62°75 64°52 64°52 64°71 64°71 64°80 64°95 64°95 66°59 67°31 67°31 70°15 70°74 70°74 72°03 72°18 74:00 74°74 74°74 76°17 77-10 77°55 78°90 79°92 79°92 81-31 (Fe) 84°21 85-17 87°34 87°34 89°37 89°37 91-04 91-04 91°58 93°18 93°18 96°32 96°32 99°55 99-91 99°91 8601°63 0601-63 04°45 05°79 05°79 06°30 KAYSER. 8608-86 09°24 14°49 17:09 19°33 20°43 23°80 24°00 25°35 26°90 27°43 29°35 31°86 32°55 34°06 30°09 30°66 37°61 38°16 40°79 45°83 46-27 52°47 52°82 53°86 54°56 56-11 57°32 57°72 60:96 61:49 61°73 63°53 68-89 69°69 71°36 72°21 72-53 75°41 76°82 77-10 78°14 78°22 ADENEY. 3608°86 12°30 15°05 17-09 1890 (Fe) 19°33 20-43 23°80 25°35 26°90 27°43 28°50 31°65 (Fe) 31°86 32°55 34°06 30°09 35°66 37°61 38°16 40°79 46°27 48°85 49°75 50°47 52°47 53°00 53°86 54°56 56°50 57°32 57°72 59°55 60°25 60°96 61°49 63°53 69°69 73°41 75°60 76°82 77°10 78°22 KAYSER. 3678°47 83°73 85°20 86-11 86-74 90°18 93°74 96°74 97-92 98-02 3700°49 01-13 01°46 02°37 03°34 05°51 12°44 14°79 15°70 16°32 16°58 17°15 17-82 19°47 22°46 24-11 24°63 25°12 27°08 28°17 30°59 30°75 31°05 32°17 33°19 37°55 37°90 38°77 39°06 39°62 Aprnty—Photographs of Spark-Spectra. 43 ADENEY. KAYSER. ADENEY. 3678°47 3742-44 3742-44 49-94 49-94 85-20 43-45 86-11 44-37 44°37 86-74 44-55 44-55 90°18 45-75 91-10 46-00 9260 46°37 92°90 47-15 93°74 48-15 94°30 48-40 96-74 49-60 97-92 50°60 52-00 52°70 3701-13 53°00 53-70 53°70 02°37 55°24 05°24 03°34 55-87 05°51 56°08 56°08 07:05 57°40 08-15 57°80 09°35 58-00 12-44 59°98 59-98 60-18 60°18 15-70 61-64 61-64 16°32 64-00 64-18 64-18 17°15 65°94 17-82 67°50 67-50 18-60 69-10 19-47 71-24 20-10 73°31 73°31 74°65 22°80 17-72 77°72 24-11 78-00 78°85* 78°90 25°12 80°20 25°59 81°31 81:31 26°25 82°35 27-08 82 89 82-89 27°33 84°30 28°17 86°19 86°19 30°59 90°65 90°65 95°05* 95-00 95°33 95°33 32°17 95°80 98-21 98-21 33°90 99°04 99-04 34-70 99°49 99-49 35-00 (Fe) 3800°39* 3800-39 37°55 03°33* 03-40 37-90 04-20 38-77 04°70 39-06 05:°57* 05°57 39°62 08-82* 08°82 # These lines are given in Rowland’s list of wave-lengths, but not in Kayser’s- ADENEY. 3908-91 09:23 12°25 15°00 21-06 23°64 24°78 26°07 31°94 3306 33°80 (Ca) 38°05 39°27 41°81 42-91 44°34 45°72 49°56 50°37 51°35 52°85 57°60 61-84 65-06 68-64 (Ca) 69-94 74°65 78°62 79°59 82°37 85°01 87-96 96-14 96°65 4003-15 05°79 06°75 07°68 08-42 09°91 44 Scientific Proceedings, Royal Dublin Society. KAYSER. ADENEY. KAYSER. 3812°87 3812-87 3906-14 13-20 08-91 14-98* 15-00 09-23 15-90 (Fe) 11-28 16-40 12°25 17-44 17°44 15-00 18-00 19-71 18-30 21-06 19-18 19-18 22-48 20-00 23-64 20°50 (Fe) 24-78 22°23 29-23 26-07 24-50 (Fe) 26°58 25°08 25°08 31:94 26°10 (Fe) 32°44 26°30 28°05 (Fe) 28-86 28°86 38-05 29-40 39:27 31-05 41:81 31-95 31:95 49°21 32°50 44-34 35°19* 35°19 45°72 38-22 38-22 49-56 38-82 50°19 39°82 39-82 50°37 41-10 50°55 42-90 51°35 43-40 52°85 46-80 57°38 50°56* 50°56 57°60 52°26* 52°26 54-90 65-06 56-60 57-69 57°69 69:94 60-05 (Fe) 72°57 60-80 74-65 62°82* 62°82 78-62 65°55* 65°55 79°59 67-97 67-97 82-04 72°39 82°37 73°66* 73°65 84-84 76-23* 76-23 85-01 79°15 87-96 80-95 89-34 84-20 84-20 94-70 84-85 84:85 96-14 87:96 87-96 96°65 90°35 90°35 91-57 91°57 4005-79 92-37 92°37 06-75 92°92 92-92 07°68 94-39 94-39 08-42 97°39 97°39 98-50 98-50 11-88 3901-39 3901-39 13°66 13°66 * These lines are given in Rowland’s list of wave-lengths, but not in Kayser’s. Avrengry—Photographs of Spark-Spectra. 45 KAYSER. ~ADENEY. KAYSER. ADENEY. 4013-87 4013-87 4127-61 4127-61 14-30 14-30 28-02 28-02 18-89 37-41 37-41 19-70 19-70 38-92 21-15 21-15 43°35 29-33 22°33 44-34 29°84 45°80 24-00 24-00 45:91 24-45 46-96 46-96 24-85 48-53 48-53 26°65 50°48 50-48 28-58 61-82 61-82 31°15 31°15 67-03 67-03 32°36 32°36 67°67 67-67 32°65 70-22 70°22 36°61 75-04 37°89 75°62 39°37 39°37 82-62 82:62 40-62 82°81 49°12 82-99 45-98 (Fe) 89-64 49°57 97-04 97-04 51:57 51:57 97°75 97-75 52-36 52°36 99-04 99-04 54-22 54:22 4200-07 4200-07 63-02 06-18 06-18 63-16 63°16 07°80 07-80 63-76 (Fe) || 12-24 12-24 64-26 64-26 14-61 14-61 64-61 64-61 17-44 17-44 67:78 67-78 20°84 20°84 68-53 68°53 25-26 Ze 26 71:56 26°83 26-83 73°15 73-15 29°47 29°47 73-26 30:47 30°20 76-90 76:90 32:48 32-48 79°44 36°84 36-84 80-78 80°78 40°19 82-95 41-23 41-23 85°57 85-57 43°23 43-23 91-22 91-22 45-00 45-05 97-19 46°36 97-97 97:97 46°52 46-52 4100°53 410053 46-90 46°90 01-91 01-91 48°30 02°44 55°87 06:07 56-05 08-00 08-00 56°79 08-22 59-15 59°15 09-80 60°17 60:17 12-91 12:90 63°55 13°53 13°53 65°77 65:77 14-29 66-16 18-68 73°12 Q1-15 21-15 77°42 23-23 23-23 78°84 SCIENT. PROC. R.D.S., VOL. X., PART I. F 46 Scientific Proceedings, Royal Dublin Society. KAYSER. ADENEY. KAYSER. ADENEY. 4289-09 4289°09 4362°87 82°36 82°36 64-27 84-50 84-49 70-58 87-21 87°21 71:36 90°69 90°69 4371-52 92-42 72°38 72°38 93-44 93°44 81-42 81-42 94°27 83°53 83°53 94-96 94-96 85°56 85°56 96-09 96-09 85-82 85°82 96-86 96°86 86-43 86-43 97-89 97-89 89°15 4301-30 89°55 02°15 90°61 90-61 4306-20 91°19 91-19 07°75 07:75 95:13 95°13 08:57 08°57 96-87 09-36 97:96 97-96 12-05 99°75 99°75 12-63 4404-93 (Fe) 13-07 4405-81 14:47 14:47 10°21 10:21 15-22 12:05 16-79 13-46 17-10 1461 | 18-60 18-60 20°63 20°63 20-05 20°04 21-01 21-01 20°74 21-63 21-63 20°97 23°14 21-45 24-96 23-12 23°15 26°18 26°18 23°63 28-62; 25°22 25-22 30°48 25-94 (Fe) 39°57 26-99 26-99 39°94 39:94 27-49 40-25 27°59 27°59 44-67 44-67 28°71 49-51 49°51 31-32 31-32 60°21 60-21 32°66 32°66 64°66 64°66 32-79 65°65 65°65 36-58 36°58 66°51 37-43 37°43 67°43 38°83 70°69 40°50 74-09 74:09 41-20 75-49 49°24 49-94 79-80 43-18 80°60 80°60 46°64 82°19) 8219 49-87 49-86 88°55 88-55 50°63 90-40 90°40 54-30 54-30 91-85 91-85 54:96 54:96 98-32 98-32 57-03 4508-19 61:37 61-37 08-72 4508-72 61-58 10-25 10-25 KAYSER. 4511-35 16°42 17-06 17-98 21-11 25°62 31:04 42°85 Apreney—Photographs of Spark-Spectra. ADENEY. KAYSER. 4511°35 4547-11 16°42 47-46 17-06 48°03 17-98 50°11 21-11 52°28 54°70 31-04 59°22 40-05 60°16 42°85 ADENEY. 4547-46 48°03 60°11 52°28 54°70 60-16 F2 47 een JW THE COHESION THEORY OF THE ASCENT OF SAP. A Repry sy HENRY H. DIXON, Sc.D., Assistant to the Professor of Botany, Trinity College, Dublin. [Read Frepruary 17; Received for Publication Frpruary 20; Published Junx 5, 1903.] ite In a series of short papers in the Berichte der Deutschen Bota- nischen Gesellschaft for 1900, C. Steinbrinck has shown that cell-walls, lignified or not, imbibed with water or dry, are toa con- siderable extent permeable to air under a difference of pressure of less than one atmosphere. This permeability to air of the walls of the conducting tracts he regards as rendering untenable the Cohesion Theory of the Ascent of Sap—a theory which Dr. Joly and I published in 1894. The fact observed by Steinbrinck is, however, by no means antagonistic to our views. In our paper, read before the Royal Society, we pointed out and showed by direct experiment that water containing large quantities of air is as capable of trans- mitting tension as air-free water.” Consequently air, diffusing through the moist lignified walls of the conducting capillaries, necessarily being in solution, would not break, or tend to break, the continuity of the water-columns within them. The interesting fact which Steinbrinck has established—viz., the permeability of these membranes to air—only affects the problem of the Ascent of Sap so far as to show that we have, in the water of the transpiration current, to deal with water containing air, and not with an air-free liquid. At the outset, Dr. Joly and I had anticipated the probability, almost amounting to a certainty, that 1 Proc. Roy. Soc., Nov. 15, 1894; p. 3, vol. lvii. ‘‘Nature,’’ Nov. 22, 1894, p- 93, vol. li. 2 Proc. Roy. Soe., doc. cit. Trans. Roy. Soc., vol. cxxvii., p. 668. Dixon—The Cohesion Theory of the Ascent of Sap. 49 the water in the capillaries contained appreciable quantities of air. This conclusion we arrived at from the observation that the fluid exuded during “bleeding” holds a considerable amount of air dissolved in it. It was for this very reason that we thought it necessary, and indeed essential, before publishing our Cohesion Theory of the Ascent of Sap, to investigate the possibility of tension existing in air-saturated water.! The air which penetrates into the capillaries of the conducting tracts has first to diffuse through the water-imbibed walls. The passage through these wet walls, of course, secures that it can only enter the contained water in a state of solution. In this state, it has been experimentally shown that air does not lead to the rupture of tensile water. Only if free gas (7.e. undissolved gas) could, as such, pass through the imbibed walls would the water in the capillaries be rendered incapable of withstanding tension. But even with regard to free gas, I venture to think that neither Askenasy nor Steinbrinck thoroughly realises how limitedly its presence, in moderate quantities, affects the transmission of tension in the water of the conducting tracts. One quotation from Steinbrinck will suffice :— ‘“‘ Bekanntlich? hat Askenasy zugestanden, dass die Gegenwart von Luftblasen in den Leitungsbahnen seiner Theorie* Schwier- igkeiten bereitet, da diese Blasen den Zusammenhang der Wasser- faden unterbrechen. . . . Stellen wir uns aber, um dieser thatsiach- lichen Schwierigkeit aus dem Wege zu gehen, die Leitungsbahnen eines etwa 20 m. hohen lebenden Baumes fur den Moment einmal wirklich ganz blasenfrei und wassererfullt vor, so wiirde ... die Bejahung des erwahnten Satzes (viz., the permeability of the walls for air) sofort das Auftreten solcher Blasen am Gipfel der Leitungsbahnen und damit den Stillstand der Aufwartsbewegung verlangen.”’ Asa matter of fact, however, the permeability of the walls to air does not necessitate the liberation of free gas in the form of 1 Trans. Roy. Soc., loc. cit. ? Ber. d. deutsch. bot. Gesell., 1900, p. 392. 3 It may be noticed that, although Steinbrinck in his earlier Papers attributes the authorship of the Cohesion Theory to Dr. Joly and myself in the first place, and to «skenasy in the second, in this latter Paper he patriotically assigns it to Askenasy alone. Cf. Ber. d. Deutsch. Bot. Gesell., 1897, p. 87, with quotation given here. 50 Scientific Proceedings, Royal Dublin Society. bubbles in the conducting tracts. And if by any chance a bubble does arise in one of the vessels or tracheids, it can only throw the lumen of that vessel or tracheid, in which it has arisen, out of function. For the free gas of this bubble cannot pass through the wet walls, but is confined within the compartment where it was formed. So the transpiration current is by no means brought to a standstill, but is merely deviated from that one element of the wood in which the rupture in the water (i.e. the bubble) has occurred. So far, then, from the occurrence of bubbles being a difficulty to our Theory of the Ascent of Sap, it seems to be a happy con- firmation of it. For it furnishes a reason why natural selection has favoured the development of conducting tracts provided with very numerous longitudinal and transverse partitions, which in themselves must act as obstacles to the free flow of water upwards. This fact we pointed out clearly in our original paper. JDL. Quite recently another criticism on the Cohesion Theory has appeared. It is published by Copeland in the Botanical Gazette." His criticism is based on his own experimental work and on a discussion of the work of others. The experiment on which Copeland lays most stress was one which he set up with the intention of illustrating the Cohesion Theory more strikingly than had been done before. The inter- pretation of his results, however, has led him to believe that this theory is inadequate. At the very outset, he admits that he is unable to explain the facts observed in his own experiment; and it would appear that his experimental methods are by no means free from error, nor is his way of interpreting them convincing. In this discussion of his work, I shall first describe his experi- ment, as I understand it, and then try to show that his results are not inexplicable; and further, that the nature of the experiment does not allow it to be used as fairly illustrating the Cohesion ~ Theory. A tube, 12°4m. high and 3 mm. in diameter, filled with plaster of Paris and water, and also containing some undissolved 1 Bot. Gaz., Sept., 1902. e Drxon— The Oohesion Theory of the Ascent of Sap. 51 air, was erected vertically. The tube was composed of short lengths, connected end to end by rubber-joints. These short lengths were filled with the plaster separately, and, as the plaster set, were boiled and cooled, and then kept immersed in boiling water for several hours. At the beginning of the experiment the whole tube terminated above in a funnel, also filled with plaster of Paris, which supported a chemically-produced semi-permeable membrane. The lower end terminated in a U-tube containing mercury and water. Ata height of 8:4 m., by means ofa T-joint, it was possible to connect a capillary tube, the lower end of which dipped under the surface of mercury. At the beginning of the experiment, while evaporation was going on from the funnel, and before the lateral capiilary was connected, mercury rose in the lower U-tube to the height of 150 mm. in four days, the rate of rise apparently slightly falling off. How much of this rise is due to evaporation above, and how much to other causes, is uncertain. There are no contemporary records of temperature and air-pressure given. After four days the funnel was removed and the upper end of the tube closed. During the next few days the lateral capillary was put into connexion with the main tube; and later on the wide U-tube below was replaced by a tube of similar bore to the upper capillary. With these arrangements mercury rose in both capil- laries. According to the final records, the mercury stood in the lower capillary at 428 mm., and in the upper one at 550 mm. above the external mercurial level. Copeland seems to believe that his results indicate a continuous rise of water in the tube, due to the difference of pressure at the top and bottom of the tube indicated by the mercurial level in the two capillaries; and that this difference was established by evaporation from the funnel, and maintained by a kind of a lag. But, he says, “an analysis showing the elementary factors by which the water is raised has baffled me, even in my own appara- tus.” And he comes to the astonishing conclusion, “that a difference in pressure of less than one atmosphere between top and bottom will lift water much more than 10 m. under the peculiar conditions here present." And again :—‘ The positive result of 1 Loe. cit., p. 165. 52 Scientific Proceedings, Royal Dublin Society. our experiment is, that the water-column being continuous, but air being present, a suction of less than one atmosphere can still operate as a suction more than 12 m. lower down.’”! In order to obtain a more definite idea from these general statements, we will apply the figures obtained by Copeland in his experiment. The rise in the upper manometer was 050 mm. This subtracted from the atmospheric pressure—say, 760 mm.— gives us the effective pressure exerted by the atmosphere at the level of 84m. It is 210 mm. of mercury. In the same way the effective pressure below is 760 mm. — 428 mm., or 332 mm. Accord- ing to Copeland, then, a column of water, 8:4 m. high, which is: equivalent to 617 mm. of mercury, is lifted and supported by a pressure equal to the difference between 332 mm. and 210 mm., or 122 mm. of mercury. Such an overbalancing or equilibrating of a greater force by a lesser may, of course, readily be shown to lead to perpetual motion. Suppose a glass-tube, having the same dimensions as Cope- land’s, and filled with water, were erected beside, and connected above and below with, the tube filled with plaster of Paris. The column of water in the clear tube being 12 m. high will exert a pressure on the water in the bottom of the plaster of Paris, at least amounting to one atmosphere. ‘This pressure, according to- Copeland’s deduction, is more than sufficient to raise the water to the top of the plaster of Paris; and so it will flow over, across the upper connexion, and maintain the clear tube full of water. In this way a continuous circulation would be established. The observations and deductions which have led to this. untenable position are due principally to the neglect of two important factors, which may be, in the first instance, briefly summarized as follows :— 1. The readings of the manometers are not a true measure of the pressure-conditions of the water in the plaster of Paris, but rather of local differences of vapour and air-pressure. 2. Plaster of Paris continues to absorb water for a long time after it has set. This absorption, by reducing the volume of water 1 Toc. cit., p. 166. Dixon—The Cohesion Theory of the Ascent of Sap. 53. in the tube, will set up local differences of pressure, which the impermeability of the plaster will maintain for long periods. 1. Copeland states: ‘“‘ The tension of the water in the plaster and that of the air and water around it at the same height must be practically the same.” So far as this statement refers to the practical equality of pressure in “‘ air” and water, it is certainly mistaken. The pressure conditions in free gas contained in water involve, in all cases, as one factor the surface-tension of the meniscus enclosing the gas, and are necessarily positive from the nature of gases. These conditions are consequently not continuous with the pressure-conditions of the containing liquid, which may be either positive or negative. Thus, although we might infer the state of tension of a liquid by observing the maximum diameter of bubbles contained in it (and whose surface-tension 1s, therefore, necessarily in equilibrium with the stress in that region of the fluid), the gas within the bubbles is actually under positive: pressure-conditions imposed upon it by this very surface-tension. Manometers, then, which would register the pressure-conditions. obtaining simultaneously in the bubbles and in the water of Copeland’s tube, would give very different readings. If the bubbles at any level are sufficiently restrained by the plaster, the gravitational pull acting against the surface-tension forces developed in the plaster will slowly put the water into a state of tension; while, of course, the gas in the bubbles would at the same time be in a state of positive pressure. But we have no reason to believe that the manometers in the experiment were in a condition to indicate tension in the liquid, even if such existed. For Copeland does not state he took any special precautions to secure unbroken continuity between the water in the plaster of Paris and the mercury of his manometers.’ 1 The neglect of securing proper continuity in the water experimented on is also. probably responsible for the results quoted by Copeland to show that branches cannot take up water, unless the latter is supplied under pressure. In these cases, as soon as the pressure is much reduced, discontinuities appear in the water which has been raised into capillaries opening on the cut surface. As transpiration proceeds, these ruptures will enlarge till they become bubbles occupying the whole of the open capillaries. Nothing comparable to this, of course, occurs in the living tree, where, as a matter of fact, we know that water passes up in presence of gas-pressure amounting to less than. one atmosphere. 4 Scientific Proceedings, Royal Dublin Society. Indeed, such continuity would have been well-nigh impossible to obtain. Hence, if the constraint, imposed by the surface- tension forces around the gas in the main tube, enabled the water there to get into a state of tension, discontinuities would have immediately appeared in the water above the mercury and at the point of contact of mercury and water. Thus, it would have been impossible for the manometers to register anything but a positive pressure, viz. the pressure of the bubbles in the main tube’ about the connexion of the manometer, or of bubbles in the manometer itself. Other considerations, to be mentioned later, render it extremely probable that tension did exist in the water in the plaster ; but the manometers, for reasons just given, could not record it. 2. The properties of plaster of Paris have often, rather unfor- tunately, been likened to those of wood. At any rate, the large resistance offered by plaster of Paris to the flow of water through it, makes it, in this particular, to differ markedly from wood. This resistance would prevent local differences of pressure being ‘quickly equalized. To give some idea of this resistance, I will quote one of several similar experiments. A cylinder of plaster of Paris, 1-2 cms. in diameter and 5 cms. Jong, transmitted, under a head of 35 ems. of water, 1:54 ces. of water in twenty-four hours. A piece of wood of Taxus baccata, containing about + of its volume of heart-wood, and having the same dimensions and with the same head of water, transmitted ‘during the first hour at the rate of 203 ces. in twenty-four hours. The difference of permeability is, however, greater than this expe- riment would indicate; for, even in the first hour, there is a considerable falling off in the rate of transmission through wood. This falling off, due to clogging which takes place at the cut surface of wood, does not occur in the case of plaster of Paris. The teaching of this experiment would appear to be, that the resistance offered by plaster of Paris to the passage of water ‘ The actual pressure of the bubbles in the main tube will be very largely decided by the dilatation they have undergone in expanding from their original to their final volume. As this will be purely accidental—depending upon the fortuitous arrangement -of plaster in the tube—we should expect that the pressure of these bubbles would be -quite different at different points in the tube. Dirxon— The Cohesion Theory of the Ascent of Sap. 50 through it is at least thirteen times as great as that of wood. ‘Taking into consideration the presence of heart-wood and the progressive clogging alluded to, we may, with greater probability, assume that the effective wood of Taxus baccata is at least 15-20 times more permeable than plaster of Paris. The narrow bore of the tube in Copeland’s experiment would emphasize this property of plaster of Paris. For, if any local differences of pressure arose, the rate of equalization of pressure would be proportional to the square of the diameter of the tube. So that, with a tube only 3 mm. in diameter, and filled with plaster of Paris, local differences of pressure would be maintained for long periods. In order to arrive at a more definite idea as to how great will be the flow of water through Copeland’s tube under the difference of gas-pressure he observed—viz. 122 mm. of mercury—we will apply the results obtained in the experiment just quoted. The amount of water passing through the tube will be proportional to the pressure urging it, inversely proportional to the length, and directly proportional. to the square of the diameter. In the experiment just quoted, the pressure was a head of 35 em. of water; the length 5cm.; the diameter 1:2 cm.; and the amount of water transmitted in twenty-four hours was 1:54 cc. In Copeland’s experiment the pressure was equal toa head of 122 mm. of mercury = 165-92 cm. of water; the length 840 cm.; and the diameter 0-3 cm. ‘Therefore the amount transmitted in twenty-four hours _ 165-92 x 5 x (8)? 85 x 840 x (1:2) "0027 c.c. In other words, with the pressure observed, it would take over a year to transmit 1 c.c. x 1°54 ¢.c. We now come to consider how differences of pressure may have arisen in Copeland’s tube. Evaporation at the beginning of the experiment may have ‘been in part responsible for pressure-differences ; but, owing to the impermeability of plaster of Paris, it seems improbable that its influence would have been appreciably felt at lower levels in the tube. 56 Scientific Proceedings, Royal Dublin Society. Another cause would have been the reduction of gas-pressure within the plaster on cooling, while the experiment was being prepared. Complete equalization of this by the flow of water would be almost indefinitely postponed, owing to the resistance offered by the plaster of Paris. But the principal cause of these pressure-differences resides in a property of plaster of Paris, which seems, up to the present, to. have been overlooked, and the possibility of which was suggested to me by Dr. Joly. On setting, even when an excess of water is present, pastes of Paris does not take up the full amount of water it is capable of, but continues steadily to absorb water long after setting is com- plete. Boiling plaster of Paris immediately after setting (as in Copeland’s experiment) does not appear to satisfy its avidity for water, but even seems to increase its powers of absorption. Whether this absorption is due to slow hydration of the calcium sulphate, or to the formation of interstices in it during crystallization, I have not determined. The former view is favoured by the fact that boiling the plaster seems to increase the effect; and it is known that plaster of Paris begins to lose water at comparatively low temperature, viz. 70° C.1 In order to show how easily this absorption of water might have produced the results which Copeland has observed, I shall quote a few of my own experiments :— Exp. i.—100 grm. of plaster of Paris was well mixed with 80. c.c. of water in a wide-necked bottle of about 200 c.c. capacity. As the plaster set, a layer of free water lay over its surface. When set, the surface of plaster exposed to the water was 4°8 em. diameter. The bottle was now transferred into a vessel of boiling water, which was kept in ebullition for two hours. The water was then allowed to cool; and the bottle lay in it for twenty-four hours. A rubber bung, with two perforations, was then fitted tightly into the neck of the bottle. Through the 1 Mendeléef: The Principles of Chemistry, vol. i., p. 611. ‘‘ Gypsum loses 14 and 2 equivalents of water at a moderate temperature.’’ (Note.) ‘* According to le Chatelier (1888), 14 HzO is lost at 120°; that is, H20, 2CaSOx is formed, but at 194° all the water is expelled. According to Shenstone and Cundall (1888), gypsum begins. to lose water at 70° in dry air. The semi-hydrated compound H20, 2CaSOQ, is also formed when gypsum is heated with water in a closed vessel at 150° (Hoppe-- Seyler).”’ : Dixon— The Cohesion Theory of the Ascent of Sap. ov perforations, a thermometer and a capillary glass tube were intro- duced, care at the same time being taken that no free air should be enclosed in the bottle, and that the capillary should be full of water. The outer end of the capillary was then arranged so as to dip below the surface of mercury. The mean volume of the capillary, determined by weighing a mercurial index, was per 10 cm. =°19 e.c. On the next day, November 13th, the position of the mercury index was observed and marked zero. DATE. HOUR. TEMPERATURE. INDEX. tC) mm- November 13, . ili. 30 15:0 1:0 be eC ae iii. 30 15-0 14:0 TO a ae ii. 30 14:5 47-0 . 16; i 45 13-3 89:5 2 yy is iii. 30 13-0 116-5 Re Gis): iii. 30 13-0 134-0 59 Ge 1. iii. 30 12°5 153°5 P01 iv. 15 13-0 165-0 8 21, iii. 30 13-0 168-0 ae iii. 20 14-0 158-0 ae os) 4 iii. 30 13-0 173-0 a 6) iii. 00 16-0 164-0 2 Cae xii. 00 14-0 179-0 £ Dia iii. 00 15:3 175-0 This table shows a continuous absorption of water during fourteen days. ‘The irregularities in the rise of the index are to be credited to the fluctuations of temperature, and also partly to the sticking of the mercury in the capillary. As might be expected from the manner of treatment, the amount of absorption, as indicated by the movement of the index, will show considerable variations in different experiments. But all my experiments have shown a comparatively large amount of water absorbed. In the experiment just quoted, the smallest rise of the index for the weight of plaster was observed. Jn the following a good deal larger absorption is recorded. 58 Scientific Proceedings, Royal Dublin Society. Exp. ii.—For this experiment 50 grm. of plaster was mixed with 50 e.c. of water. When set, the whole was boiled for two DATE. HOUR. TEMPERATURE. INDEX. December 13, . i. 15 15°58 34:0 iy MB, i. 00 13°30 263-0 yy FON i. 30 13-40 299-0 5 IG, 5 iii. 00 15°40 290°0 - AT Se xi. 30 14-60 325-5 . ewe iii. 30 16°50 317-0 MMe IS =. xii. 00 14-70 353-0 ” WO, xii. 30 15-00 378-0 55 20 xii. 00 14°65 394°8 all NBEO ra, ii. 30 13-80 499-0 39 MW, 6 i. 15 13°80 439-5 5A MB 0 xi. CO 13°10 460°0 re ROB itd xii. 00 15°58 444-0 Rey Diese xi. 00 14°10 463°5 a aWliby Oo ale xii. 00 12-10 482-5 Mug eG fc, xi. 15 12°43 502-0 45 Bile xii. 30 13°80 501'5 5 28 meee i. 00 11°50 523°5 Mego On Af xii. 30 10-00 542-0 iy Poe iv. 30 11°60 532-0 Bid ia One. xii. 00 11-20 542-5 Pe A ge i. 00 11-00 553°3 as Bil, o iy. 00 12°10 547-0 January 1, ili. 00 13°40 545-0 Ds oe xii. 00 12-60 5560 ie aut. i. 00 13-40 557°0 a By co 1. 00 11°20 590°0 a 6. i. 00 13-63 515-5 iy Ts ii. 30 14-60 | 575°5 a; Bite xi. 30 12-00 605-0 hours, and after standing in boiled water was set up in a similar Dixon— The Cohesion Theory of the Ascent of Sap. he manner to the preceding. ‘The same capillary carried the index. The surface of plaster exposed to the water was 19°62 sq. cm. In this experiment, the volume occupied by the plaster of Paris: was 62:lc.c. The distance moved through by the index (allowing for temperature was 550 mm. in twenty-six days. This move- ment of the index is equivalent to 1:045 c.c. absorption. Exp. iiii—In order to imitate the conditions of Copeland’s experiment more closely, I set up another experiment in which the plaster was confined in four glass tubes, each 16cm. long and 75mm. in diameter. After filling, these tubes were treated as closely as possible according to Copeland’s directions, and, having stood in boiled water, were enclosed in a large test-tube of boiled water, fitted with a bung carrying thermometer and capillary as before. The absorption, though slow, apparently on account of the small surface exposed to the water, was easily observable. The absorption continued without appreciable diminution over a very long time. The experiment was started December 10th. DATE. HOUR. TEMPERATURE. INDEX. December 10, . ii. 00 13°5 475 Bi A5eiys i. 00 14:0 64:5 yr 22 1. 15 14°5 107°5 3 SIRs iv. 00 13:0: 163°3 January 1, . ili. 00 14:0 151-0 0 By igs removed in these parts, leaving cavities up to 2 or 3 millimetres in diameter, containing arusty and scaly-looking residue. The Red and Grey Caernarvon Granite. The next sets we have to consider are derived from a reddish and a grey granite from Caernarvon. They also are described as “Slippery.”” They are obviously in a much more slippery state than the foregoing granite. Both these are fine-textured granites. In both a pink felspar occurs (orthoclase), but more abundantly in the red granite. A greenish black mineral mottles the surface of each, the nature of which is hardly determinable by the unaided eye. The specific gravity of the red granite is 2°612; of the grey granite, 2:642. Under the microscope, the rock is seen to be in each case of coarser structure than any we have yet examined. A large felspar (orthoclase) exists in both rocks very abundantly, and in great part densely clouded, along with erystals of small size, also much clouded. The form is columnar, and the idiomorphism well- marked, the crystals being saved from mutual interference by a small quantity—perhaps 10 per cent.—of interstitial quartz. The felspar is mostly orthoclase : some plagioclase is present, no microcline. In spite of the dense clouding with alteration- products, the action on polarized light is in nearly all cases pre- served. We thus regard the felspars, both large and small, as hard and resistant material. Adding the interstitial quartz, we find that the great bulk of the rock—not less than 95 per cent.—is composed of well-knit and very durable minerals. The quartz in parts is pegmatitic with felspar, and in parts again is ophitic in its relations with the felspar. A certain very small amount of the quartz is hypidiomorphie. Coloured constituents make up only a small part of the rock, and consist for the most part of a chloritic mineral, probably an alteration-product of mica. This mineral is pale green, shows some cleavage, but often is quite irregular in form, and exhibits a plumose extinction in steely-blue colours. A very little horn- blende is present. A black ore—probably magnetite-—also occurs, but sparingly. In the grey granite set, remains of original biotite is found. A little apatite is present along with the alteration-products of the biotite. 76 Scientific Proceedings, Royal Dublin Society. The photographed section (fig. 1, Plate III.) of the red granite enables the grain of these granites to be compared with the rocks already described, the scale of magnification being the same, @.e. 12 diameters. The cause—both of the durability and failure to preserve a rough surface—is evidently to be traced to the too overwhelming proportion of felspar. It is seen when the surface of the worn set is examined that the felspar and small amount of quartz compose the smooth part of the surface, and that this practically occupies the entire area under wear. ‘I'he very subordinate depressions are shown to be due to the chloritic mineral by the fact that this substance generally remains far down. ‘These pits are not numerous enough to offer a rough surface as wear pro- eresses. It is instructive to note that coarse as the rock is in structure, this has not availed to preserve it from becoming polished. Although slippery, almost burnished on the prominences, the surface is not so generally smooth as the Penmaenmawr diorite. Iron clings to the felspar and quartz eminences, and its solution and oxidation has stained the surface. Again we may be profitably wise after the event. There is little doubt that the uniform surface of felspar, unbroken by any large-grained constituent differing in physical characters, has led to the failure of the rock as regards retention of surface-rough- ness. It is quite possible that the abundant presence of the finely-divided and unctuous kaolinite throughout the felspar has furthermore exerted a lubricating effect as it becomes exposed under wear, much as if finely-divided black-lead was applied to the surface of the set. The point seems worthy of further investigation. The Aberdeen White Granite. I now come to a rock of much value for street pavement, and the praises of which I have heard from several experienced city engineers: thefAberdeen granite. Fig. 2, Plate III., and figs. 1 and 2, Plate IV., show photographs of this rock in thin section. Fig. 2 is magnified to the same scale as the previous photographs (twelve diameters), but figs. 1 and 2, Plate IV. only four and a half diameters, fig. 1, Plate LV. being taken with polarized light in order to display the large areas of almost limpid microcline felspar and clear quartz. Jory—The Petrological Examination of Paving-Sets. OE The granite is of a grey-white colour and of uniform and average coarse-grainedness. Its constituents are fresh and unaltered. The felspar is for a large part microcline; also partly orthoclase and partly plagioclase. The specific gravity is 2°661. The felspar varies in development from idiomorphic to allotriomorphic. Most often it is allotriomorphic. It sometimes encloses what must be more or less spherical quartz inclusions. It is free from alteration-products, or almost so. The two micas are present fairly uniformly scattered over the field in large hypidiomorphic crystals. The quartz is allotriomorphic, and forms large areas, almost equal in size to the felspar. The variation of grain of each of these constituents will be gathered from the two photographs. As the result of many measurements the dark mica constitutes about 14 or 15 per cent. of the rock. The white mica constitutes about 5 per cent. There is thus about 20 per cent. of soft mineral present. The quartz constitutes about one-half the remainder, and the felspar the other half. The worn surface of the set shows abundant and large pits floored by mica and prominences of felspar and quartz, the felspar standing generally a ditt/e higher than the quartz. It is evident that this is due to the readier splintering and fracture of the quartz, the surface of this mineral exhibiting no sign of polish, but showing a broken surface or splintery roughness. The felspar shows generally a fine matt surface, and in no case is actually polished, as in the case of the kaolinised felspars in the Caernarvon granites already described. The difference may be due to the freshness and freedom from unctuous alteration-pro- ducts of the Aberdeen felspar, or (less probably) to the microcline structure of many of these. We must notice, throughout these observations, how remarkably uninfluential the cleavage of the felspars appears to be. Quite the contrary would be anticipated under the conditions of wear. In this set we find, then, quartz wearing with a distinctly rough surface, and rather more rapidly than felspars, the fresh felspar assuming a flat but still matt surface; and both minerals, asso- ciated as they are in distinct and easily descernible grains, pre- senting a surface of considerable roughness and inequality. ‘lhe micas, constituting about 20 per cent. of the rock, and in grains SCIENT. PROC. R.D.S., VOL. X., PART I. H 78 Scientific Proceedings, Royal Dublin Society. comparable in dimensions with the grains of quartz and felspar, provide the coarser and deeper inequalities of the worn surface. The conditions here prevailing are, as experience shows, those affording a set at once sufficiently durable, maintaining its surface- roughness, and wearing uniformly. The Arklow Dolerite. The next set displays a very different surface to any of the foregoing. It is described as follows :—‘‘ Never wears smooth, but is rather soft.”” The rock is that of the Parnell quarries, south of Arklow. It is a dark, heavy rock, green in colour, and breaking with a rough fracture, and to the unaided eye reveals its grain; although the uniformity of colour renders this less conspicuous than would be the casein granitic or syenitic rocks of similar coarseness of structure. Specific gravity, 2°846. The microscope (see fig. 1, Plate V., magnification, twelve diameters) shows that the rock, which is a dolerite or diabase, is fairly rich in alteration-products. ‘These are of two kinds: sometimes evidently a chlorite, pale green, plumose, with steely-blue extinction. These areas extend into the augites present in such a way as to suggest that they represent materials derived from this mineral. The other decomposi- tion-product is flaky and nondescript, only showing a partially active or spangly field between crossed nicols. This appears to be derived from the felspar, and is probably in part calcitic. Both these substances must be classed as soft material. The fresh and abundant augite present must also be classed as badly-resisting material. The relations of this augite with the felspars is variable. Generally the augite is allotriomorphie but is also found idiomorphic. In one or two places it is ophitic. Again, in places, the felspar is moulded on shapeless augite outlines. Magnetite is fairly abundant. The only important hard material present is the felspar. It constitutes about 77 per cent. of the rock. It is in crystals of elongated habit, which vary from very small to 3 or 5 millimetres in length, and is, for the greater part at least, plagioclase. It is occasionally clouded, but retains activity in polarized light The rock must be described as a dolerite or diabase. The Joty—The Petrological Examination of Paving-Sets. 79 amount of alteration is hardly enough to justify the latter term. Some specimens which I took from the quarries some years ago, have much the same petrographical characters as the set, but alteration has gone much further.! The durable material is the sufficiently abundant felspar.. The softer materials are the alteration-products and—consider- ably harder—the augite. It is the balance of these which confers upon the set its qualities. The worn surface, in fact, shows that the summits are the felspars; while the hollows are occupied by coloured substances and the iron ores. There are no extended and smooth table-lands. The surface is markedly rough to eye and to touch. ‘The felspar-areas are not extensive enough to offer polished or smooth eminences of any injurious extent. They are well broken up by the aggregated grains of the softer minerals. These aggregates represent depressions on the surface of the set, and may measure up to 3 or 4 millimetres in diameter. The connexion between the worn surface-characters of the stone and its microscopic constitution is evident. That a rock with such a proportion of soft material would be fairly, not very, dur- able is to be expected; and that a hard material, intermixed in such proportions and with such distribution through a soft material, must afford a rough surface under attrition, might have been safely predicted. The Ballintoy Olivine Dolerite. The last set to be described here is one of typically soft character. The set is from the basic rock of Ballintoy, County Antrim. It never gets slippery, but wears rather rapidly and tmevenly. ‘This is, then, the first case we have met of a set failing to fulfil the condition of wearing uniformly. The rock is heavy and black, with rough fracture. It must be described as an ophitic olivine dolerite. Specific gravity 2-982. The olivine occurs in large crystals (see the photographed section, magnification twelve diameters, fig. 2, Plate V.) of perfectly fresh character, as well as in small scattered grains. Some of the larger grains would not have fitted into the figure, * Mr. Watts (‘ Catalogue of Ivish Minerals ”’) describes the Arklow rock as consisting of ophitic dolerites or diabases. H 2 80 Scientific Proceedings, Royal Dublin Society. and attain 5 or 6 millimetres in length. ‘The usual well- marked cleavage-cracks traverse the crystals. Around these grains, there is occasionally the appearance of flow-structure among the smaller lath-shaped felspars. The greater part of the space between the large olivine grains is occupied by large plates of augite, in which the majority of the felspars, both large and small, are ophitically included. ‘The augite is of a pale pinkish-brown colour, and is very fresh. The felspars are also fresh and unaltered. Some few felspars attain a length of 4 or 5 millimetres. I have detected no glass in the sections. A study of the worn surface of the set is instructive. The part to be ascribed to olivine as a set-mineral is at once determined. The large pits are lined with broken and splintered olivine débris, or often only a flooring of the mineral is left over. This mineral evidently breaks up readily under attrition and impact, and, although hard, must be classed with the yielding minerals. The cleavage is evidently one cause of this; probably also, in part, the liability to alteration. We may also, from examination of this set, conclude that augite cannot be regarded as a durable mineral. If it were such—at least, in adegree comparable with the felspars—the set would not wear so rapidly as it does. In point of fact, while the felspar con- stitutes but a comparatively small part of the rock, felspar and augite together constitute at least two-thirds of the rock. The rapid wear and soft character of the set must therefore be ascribed in part to the failure of the ophitic augite. So small a proportion of felspar——actually only about some 25 per cent. of the rock— unless in a quartz setting, could not be expected to resist long; but as outlasting the olivine, it confers its roughness upon the set and whatever durability it can boast of. The qualities of this set enable me to say a word here about the conditions generally influencing (3) Unirormiry or Wear. The failure to comply with the condition of uniform wear shown by this basalt, should not, I think, be ascribed to any inequalities in the gross texture of the rock but rather to its mineral composition. The conditions for uneven wear Jory— The Petrological Examination of Paving-Sets. 81 are present in every case; but only the soft and easily weathered set will show any yielding to them. It must be remembered that, like an ordinary road-surface, the conditions as regards wear are those of instability. That is, the areas which become depressed immediately become subject to an increased influence of solvent denudation and softening: for on to these parts there will be an increased gravitation of fluids, and the damp will be longer retained. If, now, minerals are present readily yielding to these influences, obviously the process will proceed acceleratively. To the readiness with which this rock (mainly the olivine) softens, I ascribe the uneven wear. The general lesson may be learnt that any rock which possesses a /arge amount of easily weathered or softened mineral—as the carbonates, zeolites, marecasite and other ores, olivine, &c.—will be liable to uneven wear. It will be apparent, from the foregoing remarks, that the prin- cipal matter to attend to in the selection of the set-rock is the balance between the hard and soft materials. About 75 to 80 per cent. of the mineral matter present should be hard and resistant. Quartz and felspar will, in nearly all cases, be the effective minerals here. The felspar is not a hard mineral if alteration is very iar gone. The test for optical activity between crossed nicols may be considered a sufficient one. ‘he soft minerals will be mica, chlorite, and other decomposition-products, olivine, and, in a less degree, augite. Although I have hitherto examined no set containing plentiful hornblende, it may be accepted as very probable that this sub- stance will not stand among the hard minerals. The pyroxenes and amphiboles may alike be classed as among the minerals not durable under the conditions of wear. The grain of the rock must also enter into account. A suffi- ciently finely divided mixture of, say, 70 per cent. hard, and 30 per cent. soft, minerals might obviously afford, under wear, a surface possessing its roughness on so small a scale as to be useless. The soft minerals must be aggregated in grains, say, from 1 to 3 or 4 mm. in diameter, and the hard be in equally large grains. Doubtless, considerable margin is allowable here on the ascending 82 Scientific Proceedings, Royal Dublin Society. scale, provided the proportions are about right. Felspars con- taining much alteration-products, but still preserving their hard- ness, should, so far as the evidence goes, be regarded as liable to wear to a polished surface. It is hardly necessary to point out here that, in the same quarry, a rock may vary considerably in character, and for this the engineer must be on the look-out. While experience in examining sets will always assist us in our power of making a correct forecast of the behaviour of the set, I trust that the remarks and photographs in this Paper will not be without use to engineers unacquainted with petrography. Many questions have arisen in the course of it which require further investigation. It is my hope that answers to them may be forthcoming. Joty—The Petrological Examination of Paving-Sets. 83 APPENDIX. EstIMaTING THE Harp anp Sorr ConstTITUuENTSs. The problem of determining the proportions of hard and soft constituents in the rock under examination is very simply and readily solved in the following manner :— The thin rock-section is placed in the microscope; and using a low power (1 inch or lower) and low eye-piece, the image of the field is projected on to a ground-glass screen above the eye-piece, any of the usual photographic apparatus being used. The ground- glass is turned rough side up. Upon this is placed a transparent divided scale prepared as follows :—A piece of logarithmic paper (divided to square millimetres or square tenths of inches) is placed in contact with a sensitive plate in a photographic printing-frame, and printed off by contact in the usual manner. ‘The result is a negative, having the divisions appearing as clear lines on a dark background. ‘This negative may be used if not too densely developed, or from this a positive is printed. The transparent divided scale is placed face-downwards upon the ground glass. We evidently now have an image of the field traversed by the lines upon the scale. On the back of this scale the outline of any particular constituent is traced by an ordinary writing-pen and ink. ‘This done, the divided plate is lifted off ; and, holding it up to the lght, the number of square milli- metres or square centimetres are estimated as contained within the ink outlines. The whole circular area of the field in square we ” JD : : ems. is ==! and hence the area occupied by the mineral can be estimated as a percentage of the area of the field. This is done for several fields, and an average taken; thus, in the case of the Arklow set described above, the approximate areas in square centimetres occupied by the coloured constituents and ores in successively taken fields were 143, 27, 174, 23, 174, 133, 16. The mean is 183. The field is just 10:1 cms. in diameter, or has an area of 60 square ems. Thus the constituents other than felspars amount to 23 per cent.; or we may assume that the felspar 84 Scientific Proceedings, Royal Dublin Society. constitutes roughly between 75 and 80 per cent. of the rock. The underlying assumption is that the relative extents of areas taken all round are proportional to the relative abundance of the consti- tuents; an assumption undoubtedly justified unless we are dealing with some special rock-structure. Thus it must be noticed that the mica in some granites may be present in fairly parallel plates. If these appear edge on in the field an allowance must be made or the quantity of this constituent would be under-estimated. This method is very rapid ; and a rough estimate of the chemical composition of the rock may be founded on it if the minerals are definite in kind. [ 85 ] EXPLANATION OF PLATE II. [ 86 ] Pal AE ia: Fic. 1. Penmaenmawr Enstatite Diorite. Magnification, 12 diameters. ‘Ordinary light. A, augite ; B, biotite; C, chlorite; M, magnetite; H, enstatite. The white parts of the field are filled with interlaced felspar along with a little interstitial quartz. Fig. 2. White Caernarvon Granite. Magnification, 12 diameters. Ordinary light. Q, quartz; F, felspar; C, chlorite (pennine); M, mica (mus- covite); EFM, intermixed felspar and minute flakes of muscovite. The mica is a very subordinate constituent, only occurring in minute scattered flakes. Original mica is apparently represented by the chloritic mineral. The felspar always contains alteration-products. Proc. R.D.S. NS, Vol. X Bemrose [t¢ Derby: DT ots Penmaenmawr Eh Dele Te. Ordinary light. A, augite ; B, biotite} The white parts of the field are ! with a little interstitial quartz light. Q, quartz ; covite) ; muscoyil® The mica is B minute scattered the chloritic mine Plate 0 [ee] EXPLANATION OF PLATE III. { 88 | STG PAC A aE amelintiale Fig. 1. Red Caernarvon Granite. Magnification, 12 diameters. Ordinary light. O, orthoclase ; F, felspar (plagioclase or doubtful); P, pegma- titic intergrowth of quartz and felspar; Q, quartz; H,. hornblende. A very little biotite (unaltered) occurs in the rock. The felspar is clouded with alteration-products. Ftc. 2. Aberdeen Granite. Magnification, 12 diameters. Ordinary light. A large crystal of microcline (M), containing included grains of quartz, fills the centre of the field; B, biotite; Q, quartz; F, felspar. The felspar contains but little alteration-products. The biotite is quite fresh. Proc. R.D.S.N §,Vol. Xx Plate It Bemrose 14 Derby. I sts light. O, orthoclase titie interg hornblende. A very little biotite (unaltere clouded with alteration-products. fee : i \ tak contaiiay K , fills theocex iy 5 thew field ; F, felgpar. Plate IL Proc. R.D.S.N S.Vol. X. Bemrose L* Derby 1 5 a 0 . ' : F é F . i [ 89 ] EXPLANATION OF PLATE IV. i, 907 | IP 1Dy vey AE 1) IL We Fics. 1 anp 2. Aberdeen Granite. Magnification, 4°5 diameters. Fig. 1 taken with polarized light; fig. 2 with ordinary light. The large crystal of microcline of fig. 2, Plate III. is shown in lower part of field, centrally. M, microcline; F, felspar; O, orthoclase; Q, quartz; B, biotite; M, muscovite. Generally the darkest parts of fig. 2 represent biotite. Proc RD S. N S.Volme Pais IW Bemrose Ltd Derby. Wi stslT Aberdeen Granite. Magnification, 4°56 diameters. Fig. 1 t ke . with polarized light; fig. 2 wi Won; The large of microcline of fig. 2, Bie ; 2 centrally. M, microcliy \ sel ate | Pl Proc. R.D. 5, N.S,Vol.X. | Bemroso Ltd Derby [ 9 |] EXPLANATION OF PLATE YV. [k 9ey | Pa Ayn Vie EirGeede Arklow Dolerite. Magnification, 12 diameters. Ordinary light. A, augite; F, felspar (plagioclase); C, chlorite; M, magnetite. re 2s Ballintoy Olivine Dolerite. Magnification, 12 diameters. Ordinary hight. O, olivine; A, plates of ophitic augite; IF, felspar, generally included in the ophitic augite; M, magnetite. Proc.R.D.S,NS.VolL. xX. Bemrose Lt Derby: V sts 5 y Arklow Dolerite. Agni 3 S » Ps A, augite; F, felspar (plagioclase); C, chlorite; M, magnetite. SYN iametets\, Ordinary light. ete! AY Plate V. 2 WIL, XC. NS Bo IETeOC, JEL IDL S) Bemrose Lt4 Derby: lege ME ON AN IRISH SPECIMEN OF DOPPLERITE. By RICHARD J. MOSS, F-.I.C., F.C.S. [Read May 18; Received for Publication May 26 ; Published Juny 18, 1903. ] In November, 1902, I received from Mr. R. Lloyd Praeger a specimen of a substance found in a peat bog in the County of Antrim ; subsequently Mr. lt. Welch, of Belfast, sent me a larger specimen from the same locality. On examination it proves to be dopplerite, and, so far as I can ascertain, this interesting substance has not previously been described as occurring in the United Kingdom. About twenty years ago I saw a specimen, which I suspect was dopplerite, occurring as a jet-like mass in dry peat, such as is used for fuel; at the time I was unaware of its nature. The specimen cannot now be traced; I only know that it was regarded as illustrating the transition of peat into coal, and that it was foundina bog in Ireland. The peat bogs and marshes of Ireland oceupy an area of 1,553,000 acres, or about a thirteenth of the entire area of the country, and it seems strange that a substance not un- frequently found in the peat formations of Germany and Switzer- land should have escaped notice, or at any rate have escaped recognition, in the great peat formations of Ireland. Mr. Bell deserves credit for recognising the substance he found as something out of the common, and worth inquiring about. Early in the last century an elaborate report on the peat bogs of Ireland was issued by a Commission appointed by Government. These reports, which are mainly of an engineering character, and are accompanied by numerous large-scale maps of the various bogs surveyed, contain occasional scraps of information of scientific interest. In one of the reports,! Mr. (afterwards Sir Richard) 1 The second Report of the Commissioners appointed to inquire into the nature and extent of the Bogs in Ireland, and the practicability of draining and cultivating them. | Printed by order of the House of Commons, April Ist, 1811, p. 48. SCIENT. PROC. R.D.S., VOL. X., PART I. I 94 Scientific Proceedings, Royal Dublin Society. Griffith states, in referring to part of the Bog of Allen in the King’s County, that there is a kind of compact or black bog which “has a strong resemblance to pitch or pitch coal, the fracture being conchoidal in every direction, and lustre glistening. This kind of bog contains very rarely any vegetable remains ; where they do occur I have always found them to consist of some of the varieties of rushes which grow in stagnant waters ; from hence we may be led to conclude that black bog was formed, or grew slowly, under water. ... This supposition is strengthened by the fact that twigs and branches of trees are sometimes found irregularly scattered at the point of juncture of the red and black bogs.” he pitch-like substance with conchoidal fracture and glistening lustre which Sir Richard Griffith observed nearly a century ago is probably of the same nature as the substance from Aussee in Styria, brought under notice by Doppler and Schrotter, Inspectors of Mines, and named dopplerite by Haidinger in 1849. According to Dana? the same substance has also been found at Gonten in Appenzell, Switzerland, and at Obbirg, near Stansstad in Unterwalden, Switzerland. More recently other occurrences have been recorded, notably at Elizabethfehn on the Hunte-Ems Canal, Oldenburg, where T. Schacht? found the stem of a pine- tree changed into dopplerite. In this case the specimen was not found in peat, but in the sand underlying a peat bog, one-third to three-quarters of a metre under the surface of the sand. The overlying bog was formerly four metres in depth, but drainage has reduced its depth to about three metres. In describing this specimen Dr. C. Claessen‘ mentions, in addition to some of the localities above referred to, Dachlmoss and Aurich, as places where dopplerite has been found. Dr. H. Immendorff® mentions the extensive occurrences of dopplerite near Papenburg, Hanover. He also refers to a deposit found during the construction of the Ems- Jahde Canal between Aurich and Upschért (Hast Friesland), which occurred as a jelly or thick liquid in the sand under the bog, in a layer twenty to forty centimetres thick, and extending to about 100 metres. Dopplerite from Pilatus in Switzerland is also 1 Sitz. Ber. Wien, 11., p. 287. 2 Handbook of Mineralogy, 5th ed., 1874, p. 749. 3 Mitteilungen des Vereins zur Férderung der Moorkultur, 1898, p. 149, * Ibid., p. 199. > Ibid., 1900, p. 227. Moss—On an Irish Specimen of Dopplerite. 95 referred to by the same authority. ‘Two interesting occurrences of dopplerite are mentioned by Dr. Immendorff as having been brought under his notice by Dr. C. Weber. in one case dopplerite of a tarry semi-fluid consistency was found filling small fissures in the boggy sand close to a stone tomb near Westerwanna in Hadeln. In the other case a funeral urn was found in a peat bog by Dr. J. Bohls; it was covered with a lid, and contained in addition to some bones an abundance of dopplerite, which in the fresh watery condition completely filled the urn. The specimen I have now to describe was found in Sluggan ' bog, on HE. M‘Groggan’s farm, at Drumsue, near Cookstown Junction, in the County of Antrim. The bog was formerly about 20 feet deep; it is now only 11 feet deep. About 7 feet from the surface, and 4 feet from the underlying boulder-clay, a gelatinous mass of dopplerite occurs, about 3 inches in thickness, thinning away irregularly into the adjoining peat. In its original moist condition the dopplerite presents the form of a stiff jelly, of a velvety-black colour. It is somewhat elastic to pressure, and less elastic to tension, breaking with a conchoidal fracture. It reddens blue litmus, is very slightly soluble in water, and apparently insoluble in acid or neutral solvents, but dissolves in alkaline solutions. In the water-oven it readily loses 85°9 per cent. of water. It shrinks greatly in drying, and becomes blacker in colour and very like jet, breaks with a conchoidal fracture, and exhibits a bright vitreous lustre. The edges of the splinters are translucent, and of a dark brown colour. It is perfectly homogeneous both in the moist and dry states, and under the microscope shows no trace of structure. When heated to ignition it burns without flame, glowing like tinder, and giving off very little combustible gas; it leaves an ash having the form of the original mass, and of a light reddish brown colour. Two closely concordant analyses of the substance dried for twenty-four hours in the water-oven gave the following result :— Calculated free from Ash. Carbon, ‘ - 90°90 Carbon, : . 08:49 Hydrogen, . Pow Hydrogen, . . 5°38 Nitrogen, . en hot Nitrogen, . ve Sead Oxygen, . . 82°93 Oxycenyn a . 84°72 Ash, ‘ og 96 Scientific Proceedings, Royal Dublin Society. In 15:3 milligrammes of the ash (the entire quantity at my disposal) I found 5:8 m.grms. of ferric oxide and alumina, includ- ing a trace of phosphoric acid, and 5:1 m.grms. of lime. An appreciable quantity of sulphate was present, but no silica except in the form of minute particles of quartz. In previously published analyses there is no record of the com- position of the peat immediately accompanying the dopplerite, when the substance was found in peat. I had an opportunity for making such an analysis in this case, and the result obtained was as follows :— Calculated free from Ash. Carbon, ‘ . 57°80 Carbon, : . 60°54 _ Hydrogen, . 5 He Hydrogen, . 5) oes} Nitrogen, . 5) lay, Nitrogen, . . 1:54 Oxygen, . . 80°54 Oxygen, . S Biles) Ash, . i . 4°53 Peat is certainly a mixture of compounds of a highly complex nature, and dopplerite may be quite as complex in character. One cannot venture to deduce formule from the ultimate composition of either substances; but, for the purpose of more clearly per- ceiving the difference between the two substances, the following formule may be taken as roughly representing the atomic relations of the constituents, omitting the ash :— Peat, . «Gro ltlea JY Oxe Dopplerite, . Cy H54 N O22 A legitimate deduction from these figures is, that the transition from peat to dopplerite is an oxidation process such as takes place in the conversion of an alcohol into its corresponding acid. It has been suggested that dopplerite is a calcium salt of one or more humus acids; but Dr. C. Claessen! has shown that this view is not tenable, because the ash varies in different specimens within wide limits. ‘The minimum recorded is 2°23 per cent., and the maximum 14°32 per cent. The organic constituents, on the other hand, show no such marked variation, except in the case of nitro- gen. If we exclude one specimen from Aussee, which differs 1 Mitteil. d. Ver. z. Ford. d. Moorkultur, 1898, p. 198. Moss—On an Irish Specimen of Dopplerite. Si rather widely from all the rest, the quantities per cent. of the dry substance free from ash, in the case of nine specimens men- tioned by Dr. Claessen and two by Professor Immendorff, are carbon, 55°55 to 60°12; hydrogen, 4°77 to 6°29; nitrogen, 0°57 to 2:27; oxygen, 32.75 to 38°23. When the dopplerite from Sluggan bog is sliced into sections about two millimetres in thickness, soaked in strong hydrochloric acid for a day, and then washed in a Soxhlet extractor, until the washings show no trace of chlorine with silver nitrate, the sub- stance remains perfectly unaltered in appearance, and when dried it is quite undistinguishable from a dried specimen of the original sub- stance. The final washings to which silver nitrate had been added slowly acquired a reddish colour, and after some time deposited metallic silver. An analysis of dopplerite treated in this way gave the following result : — Carbon, . : 3 : ‘ ; 4 57°90 Hydrogen, . : : ; ; ‘ 4:98 Oxygen and Nitrogen, : , s ‘ 36°69 Ash, ; é ; : : : : 43 Owing to the small quantity of material available it was not possible to determine the nitrogen; the experiment, however, shows that almost the entire ash may be removed without producing any perceptible change in the appearance of the substance. The constituents of the dopplerite capable of forming crystalloids with hydrochloric acid evidently diffuse out of the colloidal mass, and are thus almost completely removed. Whether the action of hydro- chloric acid, and the subsequent long-continued washing, have any effect in addition to the removal of mineral matter, cannot be decided by a single experiment. The quantity of hydrogen in the washed substance is, according to this single analysis, less than in the original, while oxygen shows a slight increase, if it be assumed that there is no change in the quantity of nitrogen pre- sent. If I can obtain a sufficient supply of material, I hope to investigate this point further. An important question to be answered is—In what condition is the nitrogen present? It is certainly present almost entirely in organic combination. M. Berthelot? points out that the action of ammonia on artificial 1 Chimie Végétale et Agricole, IV., p. 159. 98 Scientific Proceedings, Royal Dublin Society. humie acid results in an insoluble compound to which he assigns the formula C;,Hy,NO1,, which he states may be regarded as derived from humie acid, thus:—3C,,;H,,0, + NH;- H.0. He regards this compound as comparable to aspartic acid. When I first became aware of the nature of the Sluggan speci- men I decided to determine its acidity by the method devised by Dr. Tacke for determining the acidity of peat and soil. I sub- sequently ascertained that this method had already been applied to dopplerite by Professor Immendorff, who obtained the following results :— Dopplerite from Elizabethfehn.| Papenburg. | Pilatus. Carbon-dioxide liberated in three hours at ordinary temperature in an atmosphere of hydrogen, 2:79 UO7/ 1°52 Carbon-dioxide liberated at the boiling point, otherwise as above, . , ; ; ‘ 4:43 YeNE) 2°61 Assuming that Mayer’s formula for humic acid C,;H,.0, is correct, that it contains one carboxyl group, and that the liberation of carbonic acid in Tacke’s method is due simply to displacement by humic acid, the above results correspond to the following quantities of free humic acid in 100 parts of the dry substance from the places mentioned :— Elizabethfehn, . : : : ; : 70°48 Pilatus, . : : ‘ : j é 41°52 Papenburg, : : i : : ; 36°41 I have determined the acidity both of Sluggan dopplerite, and of the peat immediately associated with it, employing the following 1 These figures I quote from a private communication from Prof. Immendorff, who informs me that an error crept into his former calculations, and that the figures origin- ally published in Mitteil. d. Ver. z. Ford. d. Moorkultur, 1900, p. 232, are wrong. Moss—On an Irish Specimen of Dopplerite. 99 modification of Tacke’s method :—An accurately weighed quantity of the original moist substance, about 10 grammes in each case, was reduced to a fine pulp in a mortar, with the addition of water, and washed into a 200 ec. flask; the total quantity of water employed was about 50 cc. The flask was then closed with a cork through which two tubes pass, one tube reaches to the bottom of the flask, and is connected with a hydrogen generating apparatus. The other tube extends only a little below the cork, and communicates with the lower orifice of a double surface condenser ; the upper orifice of the condenser is connected with a CaCl, tube, and a weighed soda-lime tube. With this arrangement, and a supply of cold condensing water, it is possible to pass a current of hydrogen through the boiling contents of the flask for several hours without carrying over more water vapour than a short CaCl, tube is capable of removing. The tube through which the hydrogen enters the flask is made in two pieces; the lower piece is a thistle-tube, to which the upper piece acts as a stopper. ‘This arrangement enables one to add water, in which calcium carbonate is suspended, to the contents of the flask without admitting air or allowing hydrogen to escape. The hydrogen, before it entered the flask, was passed through a solution of potassium hydroxide in a Pettenkofer absorption tube at the rate of about two litres per hour. The application of this method to the Sluggan dopplerite and peat gave the following results :—Dopplerite, 10:05 grammes of the moist substance containing 1:413 gramme of dry matter liberated in three hours at the ordinary temperature 0-:0237 gramme CO,. On boiling for three hours a further quantity of CO, weighing 0:0411 gramme was evolved, making a total of 0:0648 gramme CO,. ‘This corresponds to 4°58 parts of CO, for every 100 parts of dry matter. Peat, 10°19 grammes containing 1-134 gramme of dry matter, liberated 0:0168 gramme CO, in three hours at the ordinary temperature, and ‘0260 gramme on boiling, making a total of 0:0428 gramme, corresponding to 3°77 parts CO, for every 100 parts of dry matter. On the assumptions already referred to these figures show that the Sluggan dopplerite in the dry state contains 72°87 per cent. of humic acid, while the peat with which it is immediately associated contains 59-98 per cent. of humic acid. If instead of Mayer’s formula for humic acid we 100 Scientific Proceedings, Royal Dublin Society. adopt the more recent formula of M. Berthelot! for the hydrate of humic acid C,,H;,0;, giving a molecular weight of 344 for a mono- basic acid, it will make very little difference in the quantities of humic acid as calculated above. I find that dopplerite decolourises a solution of phenol-phthalein made pink by the addition of a minute quantity of alkali; the reaction may possibly be utilized in titrating the acidity of this and other humus substances. 1 Chimie Végétale et Agricole, IV., p. 125. VII. TYLOSES IN THE BRACKEN FERN (PTERIS AQUILINA, Linn.). By T. JOHNSON, D.Sc., F.L.8., Professor of Botany in the Royal College of Science, and Keeper of the Botanical Collections, National Museum, Dublin. (Pratz VI.) [Read, May 19; Received for Publication, May 26; Published, Avaust 17, 1903.] A general feature in the stem of some woody plants is, that as the water-conducting sap-wood becomes converted into the hard, durable, non-conducting heart-wood, the cavities of the wood- tubes or xylem vessels become more or less blocked up by masses of large, bladder-like, thin-walled cells which have entered the cavity of the vessel by the bulging in, through the pits of the vessels, of the surrounding xylem parenchyma, at one or more points. Hach intrusion is called a tylose. Tyloses are well seen in the stem of the False Acacia tree, and of the Vine. Recently Delacroix noted that the stem of the common potato plant, which is ordinarily free from tyloses, shows them invariably when the potato plant is suffering from the microbe form of the disease commonly called ‘ yellow blight”’—an observation I have myself been able to confirm. This pathological appearance of tyloses is in keeping with their production in the stems of trees suffering from wounds, artificial or otherwise. Here the interference with the flow of sap, or other disturbance in the plant economy, may be accompanied by the more or less complete plugging up of the cavities of the xylem vessels, in part by wound gum, and in part by tyloses. Recently, in the usual course of inspection of the microscopic preparations made by the students in the botanical class in the Royal College of Science, I was struck by the appearance of the xylem in one of the preparations. One of the trachéides, as the SCIENT. PROC. R.D.S., VOL. X., PART I. K 102 Scientific Proceedings, Royal Dublin Society. xylem elements are called in the Bracken Fern (though in old rhizomes or underground stems vessels occasionally occur), was filled by well-marked tyloses. It was unfortunately impossible to say what was the cause of their formation, as the section was made from a small, detached piece of the rhizome. It would be of interest to see if, in the usual process of cutting bracken, the consequent interference with transpiration in the fern fronds causes a formation of tyloses in the underground stem. Tyloses cannot be common in the Bracken Fern, or they would have been observed already, seeing that in the course of class- teaching one sees hundreds of sections without any indication of their presence. Though tyloses are, as Molisch and others have shown, found in most of the groups of the flowering plants, according to Kuster," the only case on record of tyloses in Pteridophyta, or Vascular OCryptogams, is that of Cyathea insignis, in the old leaf-stalks of which Conwentz found them. There are several points in Kiister’s chapter on tyloses which it may not be out of place to mention here. Whether found in the cavities of xylem vessels or trachéides, in resin-passages, in secretory sacs, or in the respiratory cavity or air-chamber of stomata, they are the result of Hypertrophy. ‘This term, meaning an abnormal enlargement of a cell, without cell- division, is used in contrast to the term Hyperplasy, in which the abnormality is accompanied by cell-division. Kiister states, con- trary to views now generally held, that a tylose very rarely shows cell-division, and that the diverticulum into the ‘“‘free space ”’ is not, as usually supposed, cut off by a cell-wall from the parenchy- matous cell giving rise to it. The tyloses which may arise at many points, by the ingrowth, in the case of the xylem, of the surround- ing xylem or conjunctive parenchyma, are due to the local hyper- trophy of that part of the xylem parenchyma opposite the thin part of the wall of the vessel or trachéide, which, through some cause or other needing further investigation, bulges into the cavity of the vessel, and forms a cellular swelling. This, with or without the parent nucleus or a daughter nucleus, combines with similar swell- ings to fill up more or less completely the cavity of the xylem vessel, 1¢¢Pathologische Pflanzen-Anatomie,’’ 1903. I=IPOCSs IRs ID)o'So5 IN S05 WOlle 2S PlAUwS WI TYLOSES IN THE Bracken Frrn. Jounson—Tyloses in the Bracken Fern. — 103 producing in some cases a pseudo-parenchyma in it. Tyloses may in some cases be purely pathological, due to injury or the age of the tissue in which they occur. In some instances, as, ¢.g., in some cases of leaf-fall, they may arise in connexion with the healing of the wound, may block up the vessel, and stop the transpiration current through it ; or in some cases they may, only partly filling the cavity of the vessel, withdraw food-materials from it for the living parenchyma in the xylem. HXPLANATION OF PLATE VI. Fic. 1.—Low-power micro-photograph, showing one of the xylem trachéides, ¢, filled by tyloses. Fic. 2.—A small portion of fig. 1, more highly magnified, showing, in fair outline, a nucleated tylose cell at ¢. ites VIII. A NEW METHOD OF PRODUCING TENSION IN LIQUIDS. By J. T. JACKSON, M.A. [ Read, June 16; Received for Publication, June 26 ; Published, SEPTEMBER 30, 19038.] Twat liquids are capable of sustaining a considerable pull, tension, or negative pressure without rupture can be proved in various ways. The mercury may stick in the top of a barometer-tube and stand at a height of 33 or 34 inches. A siphon will work under the exhausted receiver of an air-pump. A column of water will remain in the longer limb of a J tube, even when the only pressure on the free surface in the shorter limb is the vapour-pressure of the water itself, and is quite incapable of supporting the column. A glass bulb completely filled with water may be gradually cooled ; and the vapour-filled space left, as the water contracts, will make its appearance, not gradually, but suddenly, and with a sharp metallic click. To produce tension in liquids by any of these methods, the liquid must have been boiled, and the glass with which it comes in contact chemically cleaned. Very high tensions have been obtained in these and other ways by Berthelot, O. Reynolds, Worthington, and others. It was shown by Joly and Dixon (Proc. Roy. Soc., 1894) that the necessity for boiling the liquid arose, not because the presence of dissolved air would render the liquid incapable of sustaining tension, as had been previously assumed, but because the presence of unwetted, or only partially wetted, dust-particles in suspension would afford points of weakness at which rupture could readily occur, and that the air expelled by boiling might be redissolved without rendering the liquid incapable of sustaining tension. The question then arises as to whether this boiling: of the liquid and chemical cleansing of the containing vessel is absolutely necessary in order to render tension either possible or demonstrable. Now it may be that evolution of gas from organic or other particles Jackson—A New Method of Producing Tension in Liquids. 105 suspended in the liquid or attached to the sides of the vessel will render a static method of producing tension unworkable, while, if the particular portion of the liquid subject to a tensile stress be rapidly changing, and the particles not given time to evolve gas, and so induce rupture, quite aconsiderable tension may be produced. To take a specific case, is it possible to subject ordinary water as drawn from a city supply main to any considerable tension with- out rupture? Such water will not stand tension for any consider- able time. Will it stand it for even a very short time ? A convenient and simple means of producing low and pos- sibly negative pressures is afforded by the well-known varia- tion of pressure in a liquid flowing through a tube of varying diameter, the pressure being low where the cross-section is small, and high where the cross-section is large. If the liquid were ! Accer ) pv\ON S nM oN! REEL SSeS Sp sy »—> Low vVeELocity HIGH VELOCITY Low VELocity HIGH PRESSURE LOw PRESSURE HIGH PRESSURE Fie. Ie perfectly mobile and the flow steady, the pressure at any point might be deduced from the measured pressure at any other point, the density of the liquid, the rate of flow, and the areas of cross- section of the tube at the two points, the relation between these quantities being But actual liquids are far from being perfectly mobile ; and the motion of a liquid in a tube is not steady if the velocity exceed a fixed small value, so that the effects of viscosity and turbulent motion would render the above formula inapplicable. If, how- ever, we assume that the current depends only on the pressure- gradient and the form and size of the tube, and does not (at least in the case of an almost incompressible liquid like water) depend on the absolute magnitude of the pressure, we see that the pressure- difference between any two points can depend only on the strength 106 Scientific Proceedings, Royal Dublin Society. of the current and on the form and size of the portion of the tube between these points, or Di — pP2 = F2(C), where the form of the function /, depends on the linear dimen- sions of the tube only; the density and viscosity of the liquid and the character of the motion between the points considered being assumed to be independent of the absolute pressure. If now the pressure-difference p, — p, corresponding to a certain value of the current C be determined from an observation in which the absolute values of both pressures are determinable, then, when C has the same value again, and the absolute value of p, can be measured, that of p, may be at once deduced. Now in the case of liquid flowing through a tube of varying section (as shown in fig. 1) the pressures in the large-bore portions of the tube as at the point marked (1) or (8) are easily measurable by manometers connected to the tube; but in the small-bore portion as at the point (2) the difficulty of inserting a manometer connec- tion would be great: the readings of the manometer might not give a true indication of the pressure in the flowing liquid (as, owing to the high velocity of flow, the effect of the eddies formed at the junction of the manometer tube with the tube in which the liquid was flowing would be large and uncertain), and finally, as soon as the pressure became negative, rupture would occur in the stationary liquid within the manometer tube. So that negative pressures, if produced, cannot be measured directly, but must be deduced from observations on measurable positive pressures. But in order that negative pressures at the narrow portion of the tube may be deduced from observed values of the current, and of the pressure in the large-bore portion of the tube by the use of the relation Pipe = F;,(C), it is necessary that some special determination of values of p, and pz be made for each valueof C. For p, the determination is easily made by a manometer, and for p, advantage istaken of the fact that a special value of p, viz. a value very nearly equal to the the vapour pressure of the liquid is produced and maintained when the flow of liquid just below the point (2) is discontinuous, for then the pressure in the space not occupied by liquid can only be Jackson—A New Method of Producing Tension in Liquids. 107 that due to vapour of the liquid, with, perhaps, a small additional pressure due to evolved air. The apparatus employed was simple; it consisted of a glass tube about -3, in. internal diameter, constricted at the middle to about =, in. internal diameter. On both sides of the constricted portion smaller tubes were joined in. These tubes, turned up- wards and closed at their upper ends, served as compressed air manometers, readings being taken on a scale fixed behind them. The glass tube was firmly fixed in a wooden base, and at one end it was connected by a short rubber tube capable of standing con- FIGs ee siderable pressure to a brass union which afforded easy means of connection with the water pipes in the laboratory. Another short rubber tube connected the other end of the glass tube to a simple form of current meter, the construction of which will be at once evident from the figure (see fig. 2). This form of current meter proved very satisfactory: it adjusted itself very quickly to variations in the current—a point which was of considerable importance, as will be seen later on. On connecting the union to a water-tap, and gradually opening the tap, the following observations were made :— Ist. Pressure-difference, as shown by manometers, and rate of 108 Scientific Proceedings, Royal Dublin Society. flow as shown by height of water in current gauge, both increased. steadily till— 2nd. The column of water in the tube ruptured at the constric- tion, a roaring or hissing sound was produced, and the water just below the point of minimum cross-section appeared milky with small bubbles. drd. At the moment of rupture or commencement of discon- tinuous motion the pressure-difference, as shown by the mano- meters, sharply increased, while the current diminished. 4th. The pressure-difference at which rupture occurred was not definite. Rupture was liable to occur if the pressure-difference was above a certain fixed minimum, and the higher the pressure- difference rose above this minimum the greater the liability to rupture. 5th. On closing the tap gradually current and pressure- difference diminished, till at a certain definite pressure-difference the water column united at the constriction and the hissing sound ceased. 6th. Rupture occurred more readily (7.e. at lower pressure- differences) shortly after the apparatus had been connected to the tap than after the water had been running for some time. 7th. In an experiment in which the apparatus was connected to the tap through a length of new grey rubber tubing, rupture of the column occurred at a definite pressure, which did not noticeably exceed the pressure at which the column would mend. The following is one series of observations :— Temperature of Air, ; » | 43057? Temperature of Water, . oo GLOSS Sane: Barometric height, . ‘ <0 29574 aime Jackson—A New Method of Producing Tension in Liquids. 109 First Ser.—Flow of Water continuous. MANOMETER READINGS. PRESSURE IN INCHES OF MERCURY. Current-gauge Above Below HeaCTE Es. Above Below constriction. constriction. constriction. constriction. 77-6 79°2 No current. 29°74 29°74 46-0 78:0 15 50-2 30°0 42°0 78:0 23 54:8 30-0 40-0 78-0 28 57-6 30:0 38-0 Ge 34 60°5 30-3 37:0 175 38 62-2 30°83 35:0 175 44 65:7 30:3 330 77-0 52 69°8 30:5 32°0 77-0 57 71°8 30°5 31:0 76°5 60 74:2 30°7 30:0 76°5 68 76°7 30:7 29-0 76°5 75 79°3 30°7 28°6 76°5 78 80°3 30-7 27-6 76:5 85 83-2 30°7 27-0 76:2 90 85:2 30°8 26°3 76°2 95 87°38 30°8 26-0 76°2 100 88:3 30°8 25°5 76-0 100 90-1 30°8 25-0 76°0 103 91:8 30:8 24-0 76-0 110 95°7 30°8 24:0 76:0 111 95°7 30°8 23-0 76-0 120 99°8 30°8 24°5 76-0 107 93:7 30°8 23-8 76-0 120 96:5 30°8 23°0 76-0 125 99°8 30°8 410 Scientific Proceedings, Royal Dublin Socie y Szeconp Sur.—flow of Water discontinuous, MANomrtTER READINGS. PRESSURE IN INCHES OF MERCURY. Current-gauge Above Below EBLE Above Below constriction. constriction. constriction. constriction. 15°5 76 100 147°5 30°8 16°4 76 102 148°5 30°8 17-0 76 95 134°5 30°8 17-0 76 90 134°6 30°8 18-0 76 87 122°3 30°8 19-0 76 80 120°5 30°8 20°2 76 76 112°5 80°8 22-0 76 70 104°2 30°8 23°6 76 65 97:2 30°8 25°5 vd 60 90-0 30°6 28°0 V7 55 82:0 30°6 30-0 7 50 76°6 30°6 32°0 i 48 71:8 30°6 33°0 V7 45 69°8 30°6 30°0 77 40 65°8 30°6 37°0 17 35 62-2 30°6 37°5 W7 34 61-4 30°6 77:0 78 No current. 29°74 29°74 Plotting these results, using as ordinates the calculated pressures, and as abscissee the observed current-gauge readings (which were heights in tenths of an inch at which the water in the vertical tube stood above the centre of the efflux tube), the curves shown in fig. 3 were obtained. It is remarkable how closely the curves approximated to straight lines. This, of course, is an indication that the pressure-gradient and the current-gauge reading both vary in the same way as the current changes, and it is a fortunate circumstance, as it affords a ready means of exterpolation. In this way, assuming that the curve so long a straight line would continue as one, the dotted portion of the curve of discontinuous flow in fig. 3 was obtained. Jacxson—A New Method of Producing Tension in Liquids. 111 In this diagram the difference of the ordinates of the curves of discontinuous and of continuous flow must represent the tension produced in the water, p/us the vapour-pressure of the water, or as 180 170 160 150 140 130 120 110 100 INCHES OF MERCURY IN NS (e) PRESSURES CONSTRICTION SG MNISO MOMS OMNGO NE ONG Ono ON COMM ONNcOnmsG READINGS OF CURRENT —METER Go: the vapour-pressure is small, the difference practically represents the tension produced. This evidently follows from the relation fi - JP» = Fz (C), as we have both the pressure p; for discontinuous flow minus the vapour pressure p:, and the pressure p, for con- 112 Scientific Proceedings, Royal Dublin Society. tinuous flow minus the (negative) pressure p, equal to the same quantity /, (C). Sealing the largest ordinate difference off the diagram it is found to correspond to the negative pressure of 77 in. of mercury, which is equivalent to 87 ft. 6in. of water, or to 37:8 lbs. per sq. in. A simple and apparently possible explanation that at first occurs is that turbulent motion in the portion of the tube above the constriction is suddenly set up, and that the observed rise of pressure, coupled with diminution of flow, is due to this cause and not to rupture of a liquid column in tension. But the observations made do not lend support to this theory ; for— Ist. The velocity at which rupture occurred was always more than nine times the velocity at which turbulent motion should commence in a tube of 55 in. diameter. 2nd. The pressure corresponding to rupture was not definite. 3rd. Freshly-wetted dust-particles in the water rendered the pressure for rupture low and definite. (See obs. 7, p. 108.) 4th. Unsteadiness of the manometers indicated that turbulent motion already exists before rupture. The way in which discontinuous flow merges into continuous is interesting. As will be seen from the diagram (fig. 3), the curve of discontinuous flow ceases to be approximately a straight line as it approaches the curve of continuous flow, and bending round meets the latter curve tangentially. The space of discontinuity in the water current, while this bent portion of the curve represents the relation between pressure and flow, does not extend over the whole cross-section of the tube, but is situated on the axis, and noticeably below the point of minimum cross-section. That the point of lowest pressure must be below the smallest cross-section is evident, as it must be where the rate of fall of pressure due to friction is equal to the rate of rise of pressure due to retarda- tion. A peculiar phenomenon, though quite a side issue, is the behaviour of small bubbles of air separated from the water in the space of discontinuity, and carried into the low-pressure manometer. As long as the flow in the tube remains discontinuous these bubbles do not rise to the surface of the water in the manometer tube, but remain submerged, and evidently in a state of rapid Jacxson—A New Method of Producing Tension in Liquids. 118 vibration. This appears to be due to eddies produced by the violent and rapid vibration of the water column in the manometer. It is probable that liquid tension plays a much more important part in nature than is usually thought. Indeed, the fact that liquids are capable of exerting a pull is often regarded as a mere laboratory experience, interesting but inapplicable in everyday life.. But it may be that certain phenomena, which have hitherto received other explanations, are really evidences of liquid tension. For instance, large stones are known to have been dislodged from the facework of sea-walls, and this has been put down to pressure of compressed air and of water behind the stone, but may it not have been due rather to pull of the receding water on the face of the stone ? tlie IX. A TRANSPIRATION MODEL. By HENRY H. DIXON, Sc.D., Assistant to the Professor of Botany, University of Dublin. [Read, June 16; Received for Publication, June 23; Published, OctoBER 15, 1903.] Ir is a matter of common observation that the leaves of tall trees remain turgid during active transpiration. This turgidity is due to the osmotic pressures of the solutions distending the proto- plasmic membranes of the cells of the mesophyll of the leaves. Pressures ranging from 6 to 16 atmospheres have been measured in these cells.1 The cells distended by these pressures adjoin directly the upper extremities of the water-conducting tracts of the plant, in which it has been shown elsewhere that the water of the transpiration current is in a state of tension.” During transpira- tion the turgid cells lose water on their outer side by evaporation. The intervention of osmotic pressure between the evaporat- ing surfaces and the stressed water makes the process somewhat more difficult to conceive than if the evaporation from the meso- phyll-cells directly stressed the liquid in the trachéidal elements of the vascular, bundles of the leaves. In order to make clear the part played by osmotic pres- sures in raising the transpiration current, according to the view advocated by Dr. Joly and myself, I have elsewhere compared® the actions taking place in the cells of the leaf with those which would proceed in an osmotic cell formed of a semi- permeable membrane containing a solution, and placed in contact with the upper end of a vertical tube filled with water, the lower end of which dips into a reservoir of water. The arrangement was supposed to function as follows:—The 1 Maquenne : Compt. rend. 1896, p. 898. On the Osmotic Pressure in the Cells of Leaves. Henry H. Dixon: Proc. Roy. Irish Acad., 1897.—Sutherst, Chemical News, 1901, p. 234, Heald: Bot. Gazette, 1902, p. 81. * On the Ascent of Sap. H.H. Dixon and J. Joly: Proc. Roy. Soc., 1894. 3 Note on the Role of Gsmosis Transp ration, Proc. Roy. Irish Acad., 1896, p. diaed Drxon—A Transpiration Model. 115 osmotic solution within the membrane draws water from the upper end of the tube, and, at the same time, distends the membrane, while evaporation takes place from the upper side of the cell into the space above. The membrane will be- come and remain distended when the difference of vapour- tension between the water at the top of the tube and in the osmotic cell is greater than the difference between that of the solution in the cell and of the space above the cell. For then the amount of water evaporated will be less than the amount entering into the cell, and the surplus will act in distending the walls. Kvaporation will continue to take place as long as the vapour- tension of the solution is greater than that of the water-vapour in the space above the upper side of the cell. I have since found that the conditions supposed in this 116 Scientific Proceedings, Royal Dublin Society. explanation may be easily realized in a simple model. Two similar semipermeable membranes are deposited in two pieces of vegetable parchment. This may be conveniently done by soaking the two pieces of parchment, first in gelatine and afterwards, when the gelatine has set, in a solution of tannin. One of the parch- ments is now spread loosely over the top of an ordinary thistle- head funnel, and its overlapping edge is bound tightly round the rim of the funnel. In order to make this junction water-tight, the outside of the rim is coated with strong glue before putting on the parchment. The second membrane is similarly bound down and glued on the rim, in such a manner as to enclose a space between it and the first. Before closing this space some dry sugar is placed on the lower membrane. After setting, the glue is ren- dered insoluble by an application of tannin. By this arrangement the funnel is closed by a lenticular cell (with more or less semi- permeable walls), containing sugar. The funnel is now filled with water, and set upright, and water is supplied to its lower end. Thus arranged it will soon be noticed that the cell above becomes turgid; and in becoming so, it of course draws up water through the supply tube. Even after the cell has attained its maximum distension, water still continues to rise in the tube, owing to an action which will be explained later. The upward current may be made apparent by supplying water to the fun- nel through a fine capillary tube, and by arranging that the water so supplied will contain a fine sediment in suspension ; its motion may be observed by means of a microscope (see figure, p- 115). Such a model may be kept in action for several days. It will, apparently, only stop when leakage of the sugar back through the lower membrane makes the liquid below isotonie with that of the cell. The action of this actual model does not resemble precisely that of the ideal model with the theoretically perfect semiperme- able membrane. This may be seen from the following considera- tions :—At the same time as water is passing into the cell from the funnel, sugar solution is leaking back into the funnel, and exuding on to the upper surface of the upper membrane, owing to the fact that the membranes are not perfectly semipermeable. This leakage may be directly observed in the streams of more Dixon—A Transpiration Model. 117 highly refracting liquid, which are seen falling down from the lower membrane into the funnel, and also by testing the outer surface of the upper membrane. Taking the leakage into account the action of the model seems to be as follows:—The osmotic pressure in the cell, due to the dissolved sugar, draws water in from below. At the same time a small amount of sugar and water passes through both the lower and upper membranes by leakage. On the outer side of the upper membrane this solution is concen- trated by ‘evaporation ; and when it becomes more concentrated than the solution within the cell, it will act osmotically on the liquid there, and draw more water to the surface. The solution leaking back into the funnel, on the other hand, is quickly diluted, and is powerless to act on the liquid in the cell. The upward flow is in this case also maintained, owing to the fact that the vapour- tension of water in the space above the cell is less than that of the liquid in the funnel. This tension is communicated through the liquid, on the outside of the upper membrane, and through the liquid in the cell. The former has a higher vapour-pressure than the space above, but lower than the solution in the cell, while the solution in the cell has a higher vapour-pressure than the liquid — above, and a lower vapour-pressure than the liquid in the funnel. Furthermore, as the cell remains turgid, these vapour-pressures must be so related to each other that the inflow of water into the cell at least balances the loss of water by evaporation and of solution by leakage. In the case of the model, the water-column which is raised in the tube is only a few centimetres in height, and consequently is urged up under atmospheric pressure into the space left for it by the evaporative and osmotic actions taking place above. But in the case of high trees, the water in the trachéidal tubes of the leaves is drawn into the osmotic cells in a state of tension, and consequently the water in these turgid cells must be in a tensile state. ‘I'o render the working of the model in this respect comparable to the transpiratory process taking place in high trees, it would be necessary to remove the atmospheric pressure below, and allow the water to be drawn up in a tensile state into the cell distended by osmotic pressure. The simultaneous presence of pressure and tension within the cell, at first sight, appears paradoxical; but a little consideration will show that it is quite possible for the solvent, water, to be in a state SCIENT. PROC. R.D.S., VOL. X., PART I. L 118 Scientific Proceedings, Royal Dublin Society. of tension, 7.e. at a negative pressure, while the dissolved substances may be at a positive pressure and be active as a distending force in the cell. Although, by thus distinguishing the pressure conditions of the solvent and of the dissolved substances, it is easy to con- ceive how the water in a turgid cell may be in a state of tension, it appeared of interest to show experimentally in the following way that this peculiar state of affairs is possible. It is well known that when a small piece is cut from the young stem of an herbaceous plant, and immersed in water, its curvature will show if its cells are distended by osmotic pressure or not; its outer surface, being less extensible, will become concave, if the cells of its tissues are distended by osmotic pressure. It will remain straight, or become convex, in the absence of these pressures. If, then, such a piece of tissue assumes and retains this concavity when immersed in a tensile water, we may be assured that an osmotic pressure is exercised by the solute, while at the same time the solvent is in a state of tension. The experiment may be carried out as follows: A long piece of glass-tubing bent into a J-form is carefully cleaned by wash- ing with caustic potash solution, followed by methylated spirit. Its upper end is then sealed, and it is nearly filled with water which has been boiled for some time. A piece of tissue cut from the stem of some suitable plant (I use the pedunele of Doronicum austriacum), after soaking for several hours in well- boiled water, is introduced into the J-tube, and passed up to the upper end, where there is a small bend made to receive it. The J-tube is now set in a vertical position, and its short limb is connected with an air-pump. By the action of the pump the atmospheric pressure 1s removed from the lower end of the column of water in the tube, and the weight of the lower parts of this column, hanging from the upper parts, puts them in tension. As the piece of tissue occupies the top of the tube, the water in it and around it is in a tensile state. It will be noticed that, although exposed to this tension for a considerable time, the tissue will retain its curvature, indicating, as we have seen, an osmotic pressure in its cells. I have exposed a piece of the peduncle of Doronicum austriacum to a tension of 50 cm. of water for two Drxon—A Transpiration Model. 119 hours, without being able to detect any diminution of curva- ture. In order to expose the water surrounding the piece of tissue to a greater tension, the lower part of the water column may be replaced by mercury. Working in this way I have submitted the osmotic cells of the peduncle of Doronicum to a tension of 75 em. of mercury for one hour. During this time the turgor of the cells remained unaltered. These experiments show the possibility of realizing experi- mentally the conditions we have assumed of pressure and tension in the transpiring cells of the leaves. In another place it has been shown! that the leaves of plants eontinue to draw up water, even when surrounded with a saturated space. Contrary to my anticipations, our Transpiration Model may be made to imitate this phenomenon. The experiment may be fitted up by enclosing the thistle-head funnel (furnished with the double membrane, containing sugar solution as described above) in a small, wide-necked bottle, which contains a little water. When the funnel is set up in position, this water lies round its stem, and the space over the membranes becomes saturated with water-vapour. With this arrangement the rise of water may be observed, as before, by the motion of the suspended particles in the capillary supply-tube. The rise of water in this form of the experiment is made possible by the distension of the cell and by the leakage of sugar solution through the membranes. Water is drawn up into the cell by osmosis, while sugar solution passes through both the upper and lower membranes. It is evident that, as long as the solution above the lower membrane is more concentrated than that in the funnel, water will pass up the supply tube. This equalization of the concentrations will require a long time, as the rate of leakage and that of diffusion through the lower membrane are very slow. In one experiment the motion of particles in the supply tube was observed for seven consecutive days, and even then the rate of motion showed no appreciable falling off. During the experiment sugar solution accumulated on the outside of the upper membrane. 1 Transpiration into a Saturated Atmosphere. Proc. Roy. Irish Acad., 1898, p. 627. L2 120 Scientific Proceedings, Royal Dublin Society. It may be supposed that the leaf-cells function just in the same manner as this osmotic cell continues to draw up water after it is surrounded with a saturated atmosphere. When the leaves of a plant are placed in a saturated space, the cells of the “mesophyll tissues, if not completely distended, will be capable of taking in more water. Some of this water may be derived from the surrounding water-vapour; but the greater part will un- doubtedly be drawn from the wood of the vascular bundles, and so will cause a rise of water in the conducting tracts of the plant. If the osmotic membranes of the mesophyll cells are not strictly semipermeable, this rise will continue, and dilution of the solutions in the cells will proceed until the fluid in the adjoining conducting- tubes is isotonic with the solution in them. The fact that the fluid exuded into a moist atmosphere contains an appreciable quantity of dissolved substances, indicates that the cells of the leaves which are active in raising water into a saturated atmosphere do not possess strictly semipermeable membranes. Hence we may, with great probability, assume that the processes occurring in leaf-cells in a saturated space, so far as the elevation of water is concerned, are extremely similar to those taking place in our model. Of course in leaves containing starch, or in those which are in a condition to carry on photosynthesis, the equaliza- tion of the concentration of the solutions in the cells and in the conduits may be long or indefinitely postponed. This is quite in agreement with the fact that submerged leaves are able to draw up water from below when exposed to light, and hardly at all, when kept in darkness." If the membranes of the model were strictly semipermeable, and the space above them completely saturated, its action would be different from what has just been described. Water would then rise in the supply-tube only as long as the cell was not distended to its maximum. As soon as it had attained its maxi- mum distension, and if its membranes were capable of resisting the osmotic pressures, a state of equilibrium would ensue, and the number of water molecules leaving the cell through the upper membrane would be balanced by the number of those enter- ing through it from the saturated space. And, in the same way, 1 Loe. cit., p. 638. Drxon—A Transpiration Model. 121 there would be a balance of loss and gain through the lower membrane. Hence the upward motion in the tube would come to a standstill. These considerations, on the actions of perfect semipermeable membranes, taken in conjunction with the observed facts of transpiration into saturated spaces, led me previously to believe that it was necessary to assume that there was, in transpira- tion, an expenditure of stored energy, and that vital pheno- mena entered into the process. But our model shows that with imperfectly semipermeable membranes, such as the leaf- cells in all probability possess, transpiration into saturated spaces is possible over long periods, and that, if photosynthesis is per- mitted, such transpiration might be indefinitely prolonged. ConcLUSIONS. A consideration of tke action of the model described in this note leads to the following conclusions :— (1) A state of tension may exist in the water (solvent) of the leaf-cells, while simultaneously the dissolved substances may be exerting an osmotic pressure. This latter is apparent from the fact that these cells remain in a turgid state. (2) The tension set up by evaporation at the surfaces of the leaf-cells during transpiration is transmitted, through the solvent in these cells, to the water in the conducting vessels and trachéids of the leaf. (3) The simultaneous presence of pressure and tension in these cells, coupled with a slight leakage of the solute through the membrane, is adequate to account for the observed facts of transpiration into a saturated atmosphere. (4) There appears no need to invoke the intervention of special vital actions, 7.e. the utilization of stored energy in transpiration. [orl 22 ia x THE LEVINGE HERBARIUM. By T. JOHNSON, D.Sc., F.L.S., Professor of Botany in the Royal College of Science, and Keeper of the Botanical Collections, National Museum, Dublin, ayo MISS M. C. KNOWLES. [Read, Junz 16; Received for Publication, June 26; Published, Octopnr 29, 1903. ] Tue late Mr. H. C. Levinge, D.L., of Knock Drin Castle, Westmeath, left by will his herbarium of ferns to the Royal Dublin Society in 1896. As is well known, the Society now possesses no collections of its own ; and in consequence, Mr. R. J. Moss, F.C.S., the Registrar, offered the herbarium to the Botanical Collections of the National Museum, which the Society had done so much, up to 1877, to create. The collection is a most valuable one, and consists of more than 4000 sheets of specimens of ferns from British India, Ceylon, and nearly all parts of the world. Mr. Levinge also left a herbarium of British Flowering Plants which remained in the possession of his daughter, Mrs. Constance Smyth, whose name, as Miss Levinge, appears often in the records of finds of Irish plants. In 1902, this lady offered the collection to the National Museum. It contains some 2000 sheets of specimens from various parts of Great Britain, and in addition more than 1000 sheets from Ireland, chiefly from County Westmeath. Following the Irish Topographical Botany of Mr. R. Lloyd Praeger, the total flora of Ireland (flowering plants and vascular cryptogams) numbers 1188 species and sub- species. The value of the Levinge Irish herbarium will be appreciated when it is mentioned that it contains specimens of 1066 of these species, 619 being from County Westmeath. In the years 1894, 1895, and 1896, Mr. Levinge himself gave an account in the Irish Naturalist, accompanied by a list, of the most interesting species then known in County Westmeath. In the present paper the object is to record the species of which specimens JOHNSON AND KnowLes—TZhe Levinge Herbarium. 1238 are found in the collection, either from County Westmeath (collected after the publication of his paper mostly), or from other parts of Ireland, and not yet recorded. This list would have been much longer but for the excellent work done in the last few years by Miss HE. Reynell. (See Lrish Naturalist, January, 1903.) RANUNCULACEZ. '*Clematis Vitalba, Linn. Knock Drin, Westmeath, Oct. 4, 1884. Ranunculus trichophyllus, Chaix. Water-hole, Portmarnock, April 30, 1890, fide A. G. More and E. F. Linton. On mud at edge of River Gaine, Knock Drin, July 8, 1891. River Gaine, Knock Drin; June 9, 1894, in running-water, fide EK. F. Linton. W. P. Hiern says of this plant, “ R. trichophyllus, or at least RR. capillaceus.’ Groves, “ R. heterophyllus without floating leaves.’ Top. Bot. has “‘ Westmeath, Ballaghkeeran, 1898—P. Rare. The distri- bution of none of the Batrachian Ranunculiis as yet fully known. The present species probably occurs in all divisions.”’ “Ranunculus floribundus, Bab. Water-course from Brittas Lake, Knock Drin, June 7, 1894. E. F. Linton, W. P. Hiern, and A. G. More call this R. floribundus. Messrs. Groves think it a hybrid with &. peltatus. Not previously recorded from Westmeath. Ranunculus penicillatus, Hiern. River Suck, Mount Talbot, Roscommon, July 26, 1891, fide W. P. Hiern. Inagh River at Ennistymon, June 26, 1891, fide W. P. Hiern. Aughrim River, Wooden Bridge, Wicklow, J. 8. Gamble. EH. F. Linton says of the plant from Wooden Bridge, ‘‘ This plant has all the appearance of var. penicillatus, but maturer plants necessary for positive certainty.” Top. Bot., ‘ Westmeath, Lough Iron, 1899—P. Lough Owel —lLevinge.” “ Probably occurs in all the divisions.” 1*, t{, or t, before a name, means ‘‘introduced,’’ ‘‘ probably introduced,’’ or ““ possibly introduced,”’ respectively. x means ‘* new to county.’’ Cyb. 2 = ‘‘ Cybele Hibernica,’’ second edition. Top. Bot. = Praeger, ‘‘ Irish Topographical Botany.”’ 124 Scientific Proceedings, Royal Dublin Society. “Ranunculus Baudotii, Godr., var. confusus (Godr.). Near New Quay, County Clare, May 18, 1892, fide W. P. Hiern. Top. Bot., “The var. confusus inland in Armagh’’; Cyb. 2, “Pools near Cork, Carroll, 1854. Brackish pools near Sutton, County Dublin, 1882, R. P. Vowell.”’ Not pre- viously recorded from Co. Clare. Ranunculus sceleratus, Linn. At edge of lake at Killua, June 6, 1894. Top. Bot., “Lough Iron, 1899—P. Rare.” “Though occurring chiefly by the coast, this plant is widely distributed in the interior. Probably it occurs in all the divisions.” COyb. 2, “Rare in many parts of the west and north-west. The curious deep-water form with long-stalked floating leaves is uncommon.” BERBERIDEZ. *Berberis vulgaris, Linn. Knock Drin (introduced), May, 1890, Miss Levinge. PAPAVERACEZ. Papaver Rheas, Linn. Drinmore, Sept. 26, 1888. Knock Drin, October 6, 1884. Top. Bot., “Mullingar, 1897 —Carr. Frequent in the west—P.” Cyb. 2, “ Locally abundant. Common in the east; rare in the west and north, but rapidly spreading.” SARRACENIACE. [*Sarracenia purpurea, Linn. Bog at Lisduff, Queen’s County, Godfrey Levinge, August, 1892. (No note to say if intro- duced by him or how it got there). | | FUMARIACEZ. Lumaria confusa, Jord. W. Corofin, County Clare, August 7, 1893. Top. Bot., “Ballyvaughan, 1895—Colgan.” “No doubt common.” Cyb. 2, “Throughout Ireland, probably.” “Seems to be less rare than F. pallidiflora; but the two plants have not been sufficiently distinguished by many observers.” *Fumaria officinalis, Linn. Drinmore, Sept. 26, 1888. Top. Bot. has no record for Westmeath. ‘‘ Distribution still imperfectly known.” Cyb. 2, “ Throughout Ireland.” JouNson AND KnowLes—The Levinge Herbarium. 125 -*Hesperis matronalis, Linn. Limerick, P. B. O’Kelly, Sept. 14, 1894. Top. Bot., “I include this species out of deference to the views of the editors of the second edition of Cybele. I have never seen it except as an obvious escape or casual, and not worth noting.” Cyb. 2, “ Apparently semi- naturalised in some parts of Ireland, and almost deserving of a place in the Irish Flora.” ** Hrysimum orientale, R. Br. Rathmines, County Dublin, July 8, 1892. Cyb. 2, “A casual, nowhere established.” tBrassica Rapa, Linn., var. Briggsii, H.C. Wats. Shore of Lake Derevaragh at Lake House, July 18, 1895. Top. Bot., “ Westmeath, Knock Drin, 1895, Levinge—W.B.E.C., 1895-1896.” “ This, the Brassica campestris of Irish records, is distributed in more or less abundance over the whole country, and in many districts appears thoroughly © naturalised, growing profusely on rough banks and waste ground, and on bare limestone “ crags” in the west.” +Thiaspi arvense, Linn. Harold’s Cross, Dublin, June 13, 1891. Top. Bot., “ Baldoyle, 1900, rare—Colgan. A plant of uncertain appearance and seldom permanent. Chiefly in the east, like many weeds of cultivation.” Cyb. 2, “In County Dublin, sparingly at Bchernabreena, 1893, and abundant in a sandy field at Rush, 1894.” VIOLACEZ. “Viola tricolor, Linn. Aran Isles, Galway Bay, P. B. O’K., July 8, 1892, fide HE. F. Linton. Cyb. 2, “No doubt occurs throughout Ireland, but is often confounded with the fol- . lowing sub-species ” [ V. arvensis]. Top. Bot., “ Probably in all divisions, but appears to be common in the north only. Not always separated from V. arvensis, and in consequence some recorded stations cannot be used. Apparently rare on the limestone.” POLYGALEZA. Polygala vulgaris, Linn. Bogbanks, N.-W. end of Lake Derevaragh, May 17, 1890, fide W. H. Purchas. Cyb. 2, “Throughout Ireland.” Top. Bot., “ Westmeath, Mullin- gar, 1897—Carr. Coosan Lough, 1898—P.” 126 Scientific Proceedings, Royal Dublin Society. *Polygala oxyptera, Reichb. Knock Drin, July, 1885, fide W. H. Purchas. Cyb. 2, ‘Probably oceurs on sandhills all round the coast.” Top. Bot. has no record for West- meath. CARYOPHYLLEZ. Arenaria serpyllifolia, Linn., var. leptociados (Guss). Ballinasloe, County Galway, June 16, 1891, Miss Levinge. Portmar- nock sandhills, Sept. 8, 1888. Cyb. 2, “ Castle mee Galway ; More.” PORTULACEZ. Montia fontana, Linn. End of Lough Drin, Westmeath, April, 1893, C. Levinge. HYPERICINEA. Hypericum humifusum, Linn. Knock Drin, Aug., 1888. Cyb. 2, ‘‘Throughout Ireland.” Top. Bot., “A rare plant in most divisions.” MALVACE. {Althea officinalis, Linn. Lough Murray, near New Quay, County Clare. P. B. O’Kelly, 21 Aug., 1891. Top. Bot., “Clare, Lahinch—More.” “ Established occasionally along the west coast.” Cyb. 2, ‘In most, if not all of its stations, an escape from cultivation.” LINACEZ. Linum angustifolium, Huds. Fassaroe, County Wicklow, July 11, 1890. Cyb. 2, ‘‘South side of Bray Head, N.C.” Top. Bot., “ Wicklow, Greystones, 1897—P. Very rare.” “This plant has a continuous range over the south and east, from Kerry to the Boyne.” GERANIACEA. Geranium columbinum, Linn. Kilronan, Aran Isles, June 14, 1894. P. B. O'Kelly. Cyb. 2, “South and Middle Ireland.” Top. Bot., “ Ballyvaughan! 1895—P. B. O'Kelly.” JouNnson AND KnowiLes— The Levinge Herbarium. 127 LEGUMINOSZ. -* Vicia angustifolia, Linn. Near the sea, north of Kilronan, Isle of Aran, P. B. O’Kelly, June 14, 1894. Top. Bot., “ The accepted idea that this plant is almost confined to the coast is misleading. It is tolerably evenly distributed over the country, rather commoner in the east, and becoming rare and local on the west coast.” ROSACEZ. +Poterium muricatum, Spach. Railway bridge wall, Maynooth station, July 31, 1889, fide A. G. More. No record in Cyb. 2, or Top. Bot. Distinguishable by the fruiting calyx-tube. *Rosa mollis, Sm. Knock Ross, County Westmont ie July 4, 1892, fide BH. F. Linton. Terryland, Galway, Sept. 5, 1888. Top. Bot., “ Probably frequent ; the Irish roses are as yet very little known.” Cyb.2, “ Bushy and rocky places, rare.” +Rosa rubiginosa, Linn. Plantations at Clonave, near Lake Derevaragh, July 24, 1895. Cyb. 2, “Hedges in Loughlanstown, Westmeath. Top. Bot., “ Westmeath, Loughlanstown (Groves)—Levinge, 1894.” “ Standing rather uncertain, but in the north has all the appearance of a native.” CRASSULACEZ. Sedum acre, Linn. Knock Drin, July, 1885. Cyb. 2, “Throughout Ireland.” ‘ Rare inland.” Top. Bot. “ Much commoner inland than was previously supposed.” HALORAGEZ. *Callitriche verna, Linn., var. vernalis (Koch). Knock Drin, Westmeath, Aug., 1888. Top. Bot., “‘ Possibly common.” Seven county records, not including Westmeath, given. *Callitriche stagnalis, Scop. Knock Drin Hill, in woods, July 21, 1893. Cyb. 2, “Throughout Ireland, probably.” “The commonest of the Irish Callitriches.” Top. Bot., “* Probably common everywhere.” Callitriche obtusangula, Le Gall. Watercourse, Lough Drin, Aug. 6, 1894. Cyb. 2, “ Lough Derevaragh, Westmeath (H. and J. Groves) ; Levinge, 1894.” ‘South and middle Ireland.” “ Apparently rare.” , 128 Scientific Proceedings, Royal Dublin Society. ONAGRARIEA. Epilobium montanum, Linn. x roseum. Knock Drin, E. 8. Marshall, July, 1895. UMBELLIFERZ. Sium erectum, Huds. (8S. angustifolium, Linn.). Kilmaglish, Westmeath, Aug., 1888. Cyb. 2, “Throughout Ireland.” Top. Bot., “ Westmeath, Lough Owel, 1899—P. Frequent in centre, and common on L. Ree.” “A rare plant in many divisions, and thins out rapidly in the north.” Scandia Pecten-Veneris, Linn. Near Corofin, County Clare, Aug. 7, 1898, H. C. Levinge. Kilmacdough, County Clare, June 20,1894. Top. Bot., ‘ Clare, Gleninagh, 1895, J. A. Audley ! Kilrush—Stewart.” ‘Probably in all divisions, but not common in any.” (nanthe fistulosa, Linn. Maynooth canal, R. Bayley, July 30, 1889. Cyb. 2, “ Throughout Ireland, almost.” CEnanthe crocata, Linn. Lisdoonvarna, County Clare, June 22, 1891. Top. Bot., “Inchiquin Lough, 1899, Miss Knowles.” “A local plant, and in a broad sense calcifuge.” Caucalis nodosa, Scop. Near Railway Station, Baldoyle, County Dublin, July 12,1890. Top. Bot., ‘ Old Bawn, rare, 1900—Colgan.” Cyb. 2, “‘ Frequent in County Dublin.” ‘From south to north.” ‘Less frequent inland than near the coast.” CAPRIFOLIACEZ. + Sambucus nigra, Linn., var. duciniata, Linn. St. Bridget’s Well, near Cliffs of Moher, County Clare, June 23, 1891. COMPOSITA. Gnaphalium uliginosum, Linn. Knock Drin, Aug. 1888. Top. Bot. ‘ Calcifuge and generally rare in the Central Plain.” Anthemis nobilis, Linn. Cromlyn, Connemara, Sept. 5, 1884. Top. Bot. ‘ Oughterard, 1899—P. Inveran—Colgan. Renvyle.” Cyb. 2, “ From south to north.” JoHnson AND KnowLes—The Levinge Herbarium. 129 *Matricaria inodora, Linn., var. maritima, Linn. Cliffs of Moher, County Clare, June 23, 1891; also at Port- marnock, County Dublin, September 13, 1888. Cyb. 2, “Throughout Ireland.” “WM. maritima, Linn., as under- stood by British botanists, has not yet been ascertained © to occur in Ireland.” Top. Bot., “I. inodora, divisions all, common.” [Of the two sheets of specimens in the Levinge collection, the one from Portmarnock, County Dublin, shows ripe heads. The fruits are not those of typical I. inodora, Linn., but agree with those of true maritima according to Coste’s description (Flore de la France). The specimens from County Clare have not heads ripe enough to allow one to use the characters of the fruits, but the plants agree in habit with the Portmarnock specimens. Comparison with specimens of I. inodora, Linn.., var. salina, Bab., both in fruit and habit, suggests fusion of the varieties maritima and salina under one name.—T. J.] Senecio sylvaticus, Linn. Lisclogher Bog, Aug. 19, 1888. Top. Bot., “Strongly calcifuge, and in the Central Plain chiefly on dry bog-banks. Not a common species in any of the divisions.” Arctium minus, Bernh. Knock Drin, Westmeath, Aug., 1888. Top. Bot., “ Westmeath, Moate, 1899—P.” “Probably common over the greater portion of Ireland, but undoubtedly rare in the north.”’ *Tragopogon pratense, Linn., var. minor (Fries). Knock Drin, County Westmeath, May 8, 1895. Cyb. 2, “Southern half of Ireland. Both the type and the var. minor are perhaps equally frequent in Ireland, but have not been sufficiently discriminated.” The specimen shows the fungus Oystopus Tragopogonis, Pers. VACCINIACEA. : Schollera Occycoccus, Roth, shows Exobasidium vaccinie, Woron. (as recorded in Irish Naturalist, 1894, page 100), a fungus causing a gall-like disease. According to Tubeuf (Pflanzen- krankheiten), Rostrup calls the fungus Evxobasidiwm occycocct. 130 Scientific Proceedings, Royal Dublin Society. ERICACEZ. Erica Mackati, Hook, var. Stuartii. Craigmore, Roundstone, Connemara, August 11, 1890. (See Irish Naturalist, August, 1902.) BORAGINEZ. ** Anchusa sempervirens, Linn. Killynon, May 14, 1890. ‘Top. Bot., no record for Westmeath. ‘“ Naturalised in the north- east, but clearly of garden origin everywhere.”’ SCROPHULARINEZ. Veronica polita, Fr. Knock Drin, July 21, 1895, legit E. 8. Marshall, Top. Bot., ‘‘ Frequent in most parts of Ireland: apparently less so in the north.” Veronica agrestis, Linn. Knock Drin, Westmeath, July 19, 1890. Cyb. 2, “ Though widespread in Ireland, this plant is apparently much rarer than V. polita.” Top. Bot., ‘s Westmeath, Moate, 1899—P.” LABIATZ. “Mentha sativa, Linn. Knock Drin, Aug. 23, 1888. Ennis, County Clare, Aug. 8, 1893. Cyb. 2, “Throughout Ireland pro- bably.” ‘Top. Bot. has no record for Clare. *Galeopsis versicolor, Curt. Miltown Malbay, County Clare— P. B. O’K., Sept., 1894. Not recorded for Clare. Cyb. 2, ‘North Ireland chiefly.” **Teonurus Oardiaca, Linn. Ballyvaughan, County Clare, P. B. O’K., Aug. 7, 1891. Cyb. 2, ‘An escape not seen recently.” Three localities given. CHENOPODIACEZ. “Chenopodium rubrum, Linn., var. pseudo-botryoides—H. C. Watson. Turlough, near Newtown Gort, County Galway—P.B.0’K., Aug. 1898. Cyb. 2, Counties Kerry, Cork, and Wexford. POLYGONACEZ. *Oxyria digyna, Hill. Near Lisdoonvarna, May, 1895, P. B. O’K. Not recorded for Clare. Cyb. 2, “Confined to West Ireland.” URTICACEA. +Ulmus montana, With. Knock Drin, April and May, 1886. Not recorded for Westmeath in Top. Bot. JOHNSON AND KnowLes—TZhe Levinge Herbarium. 131 CUPULIFERZ. Betula pubescens, Ehrh., var. denudata, Gren. Cottage Walk, Knock Drin, May 5, 1895. SALICINEZ. Salix lutescens, A. Kern. (S. aurita x S. cinerea). ‘* Front dam,” Brittas Lake, Knock Drin, April and June, 1890. Also Quarry Bog, July 28, 1892, fide K. F. Linton. CONIFER. *Taxus baccata, Linn., Knock Drin, March, 1886. Top. Bot., not recorded for Westmeath. ‘‘ Now almost confined to the west: formerly more abundant.” ORCHIDACE A. Spiranthes autumnalis, Rich. Miltown Malbay, County Clare, Aug., 1892—P. B. O’K. Cyb. 2, ‘Southern half of Ire- land.” Top. Bot., ‘‘ Clare, Ballyallia, 1900—R. D. O’Brien. Widespread but local.” LILIACEZ. Allium vineale, Linn., var. compactum (Thuill). Kilbarrack, Co. Dublin, July 8, 1890. JUNCACEZ. Juncus compressus, Jacq. Murrough of Wicklow, July, 1890. Cyb. 2 says, “True Juncus compressus (Jacq.), has not yet been ascertained to occur in Ireland.” The specimen of Juncus compressus, Jacq., has no ripe fruits; but the upper part of the stem is so clearly compressed—elliptic in outline in a cross-section of the restored stem, and not trigonous asin J. Gerardi, Loisel—that I think Mr. Levinge’s identifi- cation should be accepted, and J. compressus admitted to the Trish flora (T. J.). “Juncus lamprocarpus, Khrh., var. nigritellus (D. Don). Near Cashel Hotel, Connemara, Sept. 13, 1891 fide A. G. More. The type is common throughout Ireland, but the variety not mentioned in Cyb. 2, or in Top. Bot. 132 Scientific Proceedings, Royal Dublin Society. NAIADACEZ. Zannichellia palustris, Linn. Cahir river, Clare—P. B. O'Kelly, Oct., 1894. Top. Bot., ‘Inishmore, 1890.” Cyb. 2, “ Throughout Ireland probably.” Zannichellia brachystemon, J. Gay. Cahira river, near sandhills of Murrough, Clare—P. B. O’K., Sept. 8, 1891. Cyb. 2, “Pool on Slieve Elva, Clare, 1895.” ‘‘ Probably occurs in all districts.” GRAMINEZ. *Sesleria cerulea, Scop., var. flavescens, Moore. Castle ‘Taylor, County Galway, May 16, 1892. Vide Report of Watson Exchange Club, 1894. Top. Bot. says of type: “ Widely spread over the western limestone tracts, often occurring in great abundance.” *Keleria cristata, Pers., var. gracilis, Boreau. The coast, Baldoyle, County Dublin, July 8, 1890, fide W. RB .Linton. Lepturus filiformis, Trin. Kilrush, Clare—P. B. O’K., Oct. 2, 1894. Only recorded definitely from Limerick and Clare on the west coast. Lepturus filiformis, Trin., var. incurvatus (Trin.). Kilrush, Clare, July 13, 18983—P. B.O’K. Babington (Manual, ed. 8) says, “ Apparently only found as a ballast plant.” FILICES. Asplenium Ruta-muraria, Linn., var. pseudo-germanicum (Milde). Knock Drin, Aug., 1876. ‘Type common on walls. Var. not recorded. Polystichum Lonchitis, Roth. Knock Drin, 1845, “Not found now, 1891.” Top. Bot., “On western mountains only.” | a2 : : wat é P re b8 ‘a 0 OM “IS THE SCIENTIFIC PROCEEDINGS OF THE ROYAL DUBLIN SOCIETY. Vol, X. (N. 8.) NOVEMBER, 1904. Part 2. CONTENTS. PAGE XI.—Floating Refracting Telescope. By Sir Howarp Gruss, F.R.S., Vice-President, ihe Dublin aay ee Vil=1X, \5 : 133 XII.—Registration of Star-transits by Phe By Str Hoye Gruss, F.R.S., Vice-President, Royal Dublin Society, . 138 X111.—A New Form of Diple: Joscope. By Str Howarp Gruss, F.R.S., Vice-President, Royal Dublin Society. (Plate X.), . . 141 XIV.—A Circumferentor. By Sir Howarp Grusr, F.R.S., Vice- President, Royal Dublin Society. (Plate XI.), . : 20 143 XV.—A New Form of Position-finder for adaptation to Ship’s Com- passes. By Str Howarp Gruss, F.R.S., Vice-President, Royal Dublin Society. (Plate XII.), - . 146 XVI.—An Improved Simple Form of Potometer. By Gg. i. PETHYBRIDGE, Pu.D., B.Sc, . 149 XVII.—Willow Canker : aye a Bienes) gregaria, Sace. By T. Jonnson, D.Sc., F.L.S., Professor of Botany in the Royal College of Science, and Keeper of the Botanical Collections, National Museum, Dublin. (Plates XIII.-XV.), 153 XVIII.—The Comparison of Capacities in Electrical Work: an Appli- cation of Radio-active Substances. By J. A. McCLELLAND, M.A., Professor of Se esi ee yok eames sisi lege, ‘Dublin, : c Ohi [Continued on page 2.] The Authors alone are responsible for all opinions expressed in their Communications. DUBLIN: PUBLISHED BY THE ROYAL DUBLIN SOCIETY. WILLIAMS AND NORGATE, ink 14, HENRIETTA-STREET, COVENT GARDEN, LONDON; JUL LL 19( 20, SOUTH FREDERICK-STREET, EDINBURGH; anp 7, BROAD-STREET, OXFORD. 1904. ' Price Light Shillings and Sixpence. .} te Higg Toynnt MapRe™ CONTENTS—continued. PAGE XIX.—Preliminary Note on the Action of the Radiations from Radium Bromide on some Organisms. By Henry H. Drxon, D.8c., Assistant to the Professor of Botany, University of Dublin : and J. T. WicHam, M.D., Assistant to the Lecturer in Pathology in Trinity College, Dublin. ee XVI.- XcV LI as ‘ 178 XX.—An Experiment on the Possible Effect of f High Pressure on the Radio-activity of Radium. By Me E. Wi. 08) D. See, Lie Meeby eto d . 193 XXJ.—On the Renney of the o Alkyl Todides. By esGr . Doxa Me AR er, sue 195 XXII.-—On the ae ot Water-jets, and the effect of Sound thereon. By Purp 1. Betas, Science Scholar, Department of Agri- culture and Technical Instruction for Ir eland, Royal College of Science, Dublin. (Plates XIX.—XXII.), : : . 203 XXIIJ.—Remarks on the Cases of Carbon-monoxide Asphyxiation that have occurred in Dublin since the addition of Carburetted Water-gas to the Ordinary Coal-gas. By E. J. McWEENEY, M.A., M.D., D.P.H., M.R.J.A., Professor of Pathology at the Catholic University Medical’ School ; pea to the Mater Misericordie Hospital, Dublin, : 217 XXIV .—Photographs of Spark-Spectra from the Large Rowland Spec- trometer in the Royal University of Ireland. Part II1.: The Ultra-violet Spark-spectra of Platinum and Chromium. By W. E. Aprenry, D.S8c., A.R.C.Sc.1., Curator and Examiner in Chemistry i in the Royal Univer: sity of Ireland, 235 XXV.—The Pre-glacial Raised Beach of the South Coast of Ireland. By W. B. Wricut, B.A., and H. B. Murr, B.A., F.G.S. (Plates OUI OO, ee ; : . 250 XXVI.—Vapour-pressure Apparatus, By James J. HurcHinson, . 325 XX VII.—Formation of Sand-ripples. By J. Jory, B.A.I., D.Sc., F.RB.S., F.G.8., Professor of Bcuney and Mineralogy 1 in the Uni- versity of Dublin, . 328 XXVIII.—On a Method in Qualitative Malye for Detenunne the presence of certain Metallic Oxides, By CHaRLus R. C. TicHBORNE, F.I.C., Div. P.H., F.C.5., ete., : ‘ - dol f 183 XI. FLOATING REFRACTING TELESCOPE. By SIR HOWARD GRUBB, F.R.S., Vice-President, Royal Dublin Society. (Puates VIT.-IX.) [Read, Novemper 17; Received for Publication, November 20, 1903; Published, Frpruary 10, 1904.1 On the 21st February, 1894, I read a short paper before the Royal Dublin Society (Scient. Proc. vu1., pt. 3, p. 252), describing a suggested form of equatorial suitable for reflecting telescopes of the Newtonian type, in which the principle of flotation was carried further than had hitherto been attempted. The object of proposing the flotation principle for these les equatorials was to surmount the difficulty which is encountered when the dimensions and weights of the moving parts become excessive. The weights of the moving parts of such an instru- ment increase about as the cube of the diameter of the object- glass or mirror, whereas the bearing surfaces cannot be conve- niently increased in a larger proportion than the square; the consequence is, that the weights on the bearings become excessive, and great difficulties arise in reducing the friction sufficiently to enable the ponderous masses of metal contained in the mounting to be driven by the clock-work with that amount of steadiness and uniformity which is absolutely necessary for modern astro- nomical observations. . Having lately been requested to submit designs for a refracting telescope of 48 inches aperture, I was led to consider how far the same flotation principle could be utilised in the case of refractors. In order to effect this, I propose to adopt a very practical and ingenious modification of the ordinary form of refracting telescope suggested to me a few years ago by Professor Hale, Director of the Yerkes Observatory in Chicago, where the largest existing refractor is installed. He desired to have a refracting telescope SCIENT. PROC. R.D.S., VOL. X., PART II. M 134 Scientific Proceedings, Royal Dublin Society. of unusually long focus mounted as an equatorial, but the long focus necessitated a very large equatorial if constructed in the ordinary manner. He therefore suggested that the tube should be made one-half the length of the focus of the telescope, and that a plane mirror should be inserted at the lower end of the tube nearly at right angles to the axis, which would reflect the rays, but without altering their convergence, to an eye-piece or photo-plate at the upper end of the tube situated beside the object-glass. This renders the outward form of the sonuenne telescope very similar to that of the Newtonian reflector, and enables us to apply the same principle of mounting as I suggested before in the case of the reflecting telescope. In the present case I had to design an instrument for a low latitude, 25°; and I found that the flotation principle could be even more perfectly carried out in low latitudes than in higher latitudes, such as ours. In the design before submitted for the reflecting telescope, the flotation system, though it allowed of the bearings being relieved of a very large percentage of the weight of the moving parts, was not quite perfect, because, as will be seen by reference to the drawings which accompany that paper, the polar axis (which consists of a double-steel framework, embracing a sphere, which sphere forms the declination axis) is more or less immersed in the water according to the hour-angle of the object under observation. In constructing such an equatorial for low latitudes, however, as in the present design, this flotation principle can be carried further ; in fact, it can be made theoretically perfect, so that, if desired, the whole weight of the instrument can be relieved from the bearings, and the balance made equally perfect in all possible positions. It is desirable, of course, to leave a certain percentage of the weight on the bearings in order to ensure perfect steadiness ; but any percentage, up to, say, 95 per cent., can be relieved by the water-pressure; and this is equally true of both declination and polar axes. In the present design (see Plates VII. and VIII.), which is. for a refracting telescope of 48 inches aperture, the moving parts of which would weigh about sixty tons, the tube is enlarged near Grusp—Floating Refracting Telescope. 135 its lower end into a sphere; the construction and distribution of the weights being such that the centre of gravity of those portions of the instrument carried on the declination axis, that is to say, the tube, object-glass, mirror, and inner sphere, shall precisely coincide with the centre of the sphere. It this be correctly carried out, such a body will, of course, float in water in a state of perfect equilibrium at any angle and in any position. The polar axis consists of a slightly larger sphere, supplied with bearings placed or mounted at the proper angle, in which the telescope with its inner sphere is placed ; and sufficient water is supplied to the space between the two spheres to almost float the telescope with its inner sphere in the outer sphere. The outer sphere, in which the distribution of parts is likewise such that the centre of gravity corresponds with the centre of the sphere, is itself floated in a third outer sphere or portion of a sphere, which is supplied with sufficient water to float the whole moving parts, including the telescope, with its inner sphere and polar- axis sphere. ‘The result of the whole is that all parts are in perfect equilibrium no matter what positions they are placed in, so that the flotation principle in this case is carried out in the most effective manner; and any portion of the weight of the instrument that is desired, from none up to the whole weight, can be relieved off the bearings either of the polar axis or the declination axis, and still leave all parts in a perfect state of equilibrium. It will be noted in the design I propose, that the driving arrangements consist of practically an independent equatorial instrument, the polar axis of which is placed in line with the polar axis of the equatorial proper, which carries the telescope, and only connected thereto by a simple driving arrangement, so that any strains of flexure which may possibly occur in the ponderous masses of the equatorial can in no way affect the smaller equatorial, which might be called the driving equatorial. The advantages to be derived by the adoption of this flotation principle for such an equatorial are :— 1. That no matter what the weights of the moving parts are, there should be no difficulty in dealing with them, as any per- centage of the weight can be retained by water-pressure if all details be well designed, and such an instrument should work M2 186 Scientific Proceedings, Royal Dublin Society. with the ease and accuracy of an instrument of one-tenth the weight. 2. The dimensions of the whole instrument, the building to accommodate it, and dome to cover it, are all reduced in a very large proportion, and the cost decreased accordingly. 3, On account of the short radius which the eye-piece describes as compared with other forms of telescope, the difficulties con- nected with the status of the observer—that is, the means for the reduced. As regards this last point, it will be seen that a pair of convenient staircases are arranged, one on each side of the tube, carried upon rails laid on the upper floor. This upper floor forms a part of the dome, and revolves with it. The telescope tube is supplied with attachments Boe eye-pieces in four places; and convenient access to one or other of these eye-pieces can always be had from some part of these travelling stair-cases. For comparison’s sake, a design of the same-sized telescope, drawn to a smaller scale (Plate IX., fig. 3), is given of the ordinary or German form, complete with hydraulic floor, &c., which would be almost indispensable in this case; and Plate IX., figs. 1 & 2, gives an outline of the buildings and dome required for the ordinary and the flotation instruments side by side, and to the same scale. No hydraulic floor is necessary in the case of the flotation telescope, as the difference in the height of the eye-piece for various altitudes of stars never exceeds 18 feet, while in the ordinary form it amounts to about 40 feet. For convenience of painting, oiling, &., arrangements are provided by which an additional quantity of water can, if desired, be added either to the outside trough or between the two spheres, thus lifting, in the one case, the whole instrument, including the polar axis, out of its bearings; and in the second case lifting the declination axis and telescope out of its bearings, thus com- pletely avoiding any necessity for employing cranes or other tackle for such purposes. It should be borne in mind that this instrument has been designed for a latitude where frost is never likely to occur to an *YOUL 9UO 0} JoaT OZ IVIg 4SOM UWLOIT PIMOTA SV UOTJOIS UI UMOYS SuIping ‘erdrourad woNvjoy oy} uo poyunout A[[etIoyenbe ‘adoosejay, Surjovrzey OUT-gF TIA S2VIg X TOA “SN “SA 907g \ es — J oh ’ el - 4 /: 5 a = mt « ne i: ’ 2 " r oly » ws ‘i “ oo ai alee ae i ~~ aang Saree baa reeds ke - | ate z P. & - - * ry ¥ 7 5 BT 2 LS Ke ores . wi> ’ . . . nae Fo caer aL ewes x oF Lt e ‘ ‘ : ; . ¥ wea J MG fe d ys i.e ot * “e OP id he ee oe “YOUL 9UO 03 J9eT YZ EVI “Y}IOU WOIF POMOLA Sv UOIJOES UL UMOYS Surpting ‘epdroursd uorrjoy oy} uo pajunow Ayprisojenho ‘edooseyay, Suyvedeyy Yout-gF TIA Stv1g YX JOA “SN “SAY ‘907g Proc. R.D.S., N.S., Vol. X. Puate IX. RISSSSSSSSSSSSTSSSaeat Figs. i., ii.—Design illustrating the relative sizes of building and dome required for the accommodation of fig. i., a 48-inch Equatorial mounted on flotation principle, and fig. ii., a 48-inch Equatorial of the ordinary form of mounting. Fig. iii.—48-inch Refracting Telescope, equatorially mounted. Lifting-floor worked by hydraulic ram. Scale about 26 feet to one inch. Viewed from west eee ee een Ce eee Grusp—Floating Refracting Telescope. 137 extent sufficient to freeze the water; but if required for higher latitudes, there should be no difficulty in adding some chemical to the water that would prevent this inconvenience. All the various motions of the instrument, setting in right ascension and declination, &c., also movement of dome, are arranged to be driven by motors. The declination readings would be taken from an are of about 10 feet radius, attached to the outer sphere, alongside the opening through which the telescope protrudes; and this is quite close to the eye-piece and observer. Arrangements for reading the right-ascension circle can also, if desired, be made to enable the observer to take his readings while at the eye-piece of the telescope. An obvious objection may be raised to this form of instrument on the ground that with sudden changes the upper end of the tube will probably be of a different temperature from the lower, where it is immersed in the water; but I have already provided for this in my design for the reflecting instrument by making the tube double, and keeping a constant circulation of air of the same temperature as that surrounding the upper part of the tube passing between the double envelopes and round the sphere at the lower end. Similar arrangements are provided in this case. I may mention that, since I proposed this last arrangement for the reflecting telescope, a very similar plan has been actually put into practice at an American observatory with very satisfactory results. r 138 J XG: REGISTRATION OF STAR-TRANSITS BY PHOTOGRAPHY. By SIR HOWARD GRUBB, F.R.S., Vice-President of the Royal Dublin Society. [Read, Novemper 17; Received for Publication, NovemBer 20, 1903; Published, FEBRvARyY 10, 1904. | Norwitustanpine the great assistance that photography has proved in many branches of astronomical work, very few serious attempts have been made to register transits by its means, though at first sight it would seem to be eminently fitted for this particular work. It seems comparatively an easy problem to cause the star- image passing across a photographic plate to form its own register by some such means as instantaneously obscuring the image at stated intervals, thus forming a broken instead of a continuous line, the breaks corresponding to certain seconds of the standard clock. Such an arrangement has been tried with fair success by Mr. W. E. Wilson, F.r.s., amongst others; but at or near the Equator, where the apparent movement of the star is greatest, and when observations are of the most importance, it is only the larger stars that can be thus treated. Smaller stars are not sufficiently brilliant to impress their trail even on the most sensitive plates, and photographers will understand that it is not desirable to use highly sensitive plates for this purpose, as the higher the sensitive- ness, the coarser the granulation of the film; and when delicate microscopical measures have afterwards to be taken of the positions of the star-images, these highly sensitive but coarsely-grained plates are unsuitable. In order, therefore, to provide an efficient photographic transit instrument, it is necessary to cause the plate to travel with the star-image, and register the seconds by some other means; but here a difficulty arises, for the star-images pass across the plate at “speeds varying with the angle of declination north or south of the Equator. Gruse—Registration of Star-Transits by Photography. 189 They pass fastest at the Equator, and would be absolutely stationary at the exact Pole if there happened to be a star there. The clockwork arrangements, therefore, for carrying the plates would have to be regulated according to the declination of the star under observation—a difficult problem. I suggest the following as a possible convenient solution of the question :— The transit instrument itself would be of the ordinary form, Iie, Te and mounted as usual on a pair of piers or columns, the only difference necessary being that the object-glass, instead of being as usual at the upper end of the tube, must be in the centre, where the horizontal axis intersects the tube. The lower end of the tube would be quite open. The photo- plate, p, would be carried, not on the tube, but on a metal arc attached to the upper end of a polar axis, which is mounted in a 140 Scientific Proceedings, Royal Dublin Society. casting quite independent of the transit instrument, but so placed that a prolongation of that polar axis would pass through the horizontal axis of the transit and the optical centre of the object- glass, and the metal arc would be so constructed that its centre also coincides with the same centre of the transit instrument. With this construction, the photo-plate, whose carrier can be slid up and down the are, will always be at the focal distance of the object-glass from the optical centre of that glass; and therefore any star-image falling on it will be in correct focus; and if the polar axis be driven uniformly by clockwork as in the ordinary equatorial, the plate will always travel at the correct rate for images of any declination formed upon it; consequently a plate exposed in this apparatus should, when developed, show a round image of a star. ; For registering the seconds on the same plate, a diaphragm would be mounted at one end of the axis of the transit instrument with optical means by which an image of that diaphragm will be formed on the same plane as the star-images. This diaphragm would be strongly illuminated by a small electric lamp, and sup- plied with some kind of instantaneous shutter so arranged that every second, or every alternate second, an image of this diaphragm would be flashed on the plate. Preferably the design cut on the diaphragm would be as in fig. 2, so that the plate when developed would be as in fig. 3. TUTTE VON TEE Fre. 2: Fie. 3. It will be observed that every fifth second is “ dropped ””——that is to say, every fifth flash is omitted on one side, while every tenth second is dropped on the other side. This is to facilitate the identification of the seconds. te, Brocs ReDES.) Nese Viol. Xe Prats. X. Improved DrpLerDoscore. Scale about half actual size. ; @4h. J XIII. A NEW FORM OF DIPLEIDOSCOPE. By SIR HOWARD GRUBB, F.RB.S., Vice-President, Royal Dublin Society. (Pirate X.) [Read, Novemner 17; Received for Publication, NovemBer 20, 1903; Published, Frpruary 10, 1904. | Even in these days of rapid travelling and telegraphic communica- tion there sometimes exists a difficulty in ascertaining true time in country-places. The very causes which operate to render the distribution of time more easy also necessitate a greater accuracy than was necessary in the old coaching days. The sun-dial, therefore, is now valued more for its old-time picturesque appearance than for its utility. We have practically nothing available between this and the astronomical transit-circle, which instrument is altogether too delicate to entrust to any but highly-skilled hands. Many years ago I found a description of an ingenious instru- ment called a ‘“ Dipleidoscope,”! which consisted of a right-angled prism fixed in such a position that the Sun when near the meridian could be viewed in it obliquely. Two images were seen—a faint one, due to the partial reflection from the first surface of prism, and another very brilliant, being doubly reflected from the two inner surfaces. As one of these images was due to single reflection, and the other to double reflection, they appeared to move in opposite directions; and if the prism was properly set, the two images overlapped at the moment the Sun passed the meridian. The instrument was not very effective, because, firstly, it was necessary to view the- images through a very densely-coloured glass to render bearable the intensely brilliant image formed by 1 “A Description of the Dipleidoscope.”” By E. J. Dent, 1843. 142 Scientific Proceedings, Royal Dublin Society. the two internal total reflections, rendering the other image hardly visible; and, secondly, as there was no magnifying power, it was not easy to form a correct judgment within some seconds of the time at which the images overlapped. _ Some improvements have occurred to me, which I effect in the following way :— 1. By covering one-half of the. prism with a film of sulphide of lead, such as we use in the new gun-sights, I am able to make the two images equal in intensity. 2. Instead of viewing the images directly, I add a lens by which images of any desired size are thrown on to a wall or screen. In the instrument exhibited, the lens is about 20 feet in focus, and forms solar images of about 2 inches in diameter. These images move relatively to one another at the rate of about one- thirtieth of an inch per second, so that it is quite possible for even an unskilled observer to register the time within a second, which is sufficient for all ordinary purposes. A table of “Equations of Time” could be arranged con- veniently to the instrument, so that the true mean time could always be deduced from the solar time, as given by the instrument. With these modifications, the little instrument becomes a really practical tool, which will be found of considerable use in districts where it is not otherwise possible to obtain correct time. IPOs LBolDatStoy WoSto5 Ole XC. Prater XI. Circumferentor, or instrument for the rapid measuring of vertical and horizontal angles. Scale about half actual size. tas XIV. A CIRCUMFERENTOR. By SIR HOWARD GRUBB, F.R.S., Vice-President, Royal Dublin Society. (Prats XI.) [Read, Novemper 17; Received for Publication, NovemBer 20, 1908 ; Published, Frpruary 10, 1904. ] Tue instrument of which the accompanying figure shows a vertical section is primarily intended for rapidly observing horizontal and vertical angles for military purposes; but it is expected that it will also prove of use for many other purposes, notably for underground survey work, mines, &c. SSS NN Pi Ri? A Wd. We a ASSL, SSAA N AARNE RRAAARRA NESE NAN EESSERM N fo g Ni NG ee N INNA WY, GS (SESS i NE a j Its construction is exceedingly simple. A circular box, 4, d, is provided on the inside of its rim with a transparent circular scale, s, divided into tenths of degrees. The lid, 7, 7, or upper portion of the box, is so constructed that when in use it revolves freely upon the lower. This lid carries on its under side a pair of plano-convex lenses, with the convex faces towards one another, the combined focus of (144 Scientific Proceedings, Royal Dublin Society. this pair of lenses being exactly equal to the radius of the circular scale; and they are so placed in the box that the optical centre of the pair is in exact coincidence with the centre of the box. Behind this is placed a right-angled prism which reflects the rays in a vertical direction on to a piece of parallel glass, p, hinged to the outside of the lid, and by which the rays are reflected in a horizontal direction into the eye of the observer. This piece of parallel glass, which folds down on the lid for convenience of packing, is, in its working position, placed at an angle of about forty-five degrees to the lid, and is coated with the same film of sulphide of lead that I use for gun-sights. This film has the property of reflecting nearly half the light which falls upon it, and of transmitting the other half. The result is that the eye, placed as shown in the figure, sees the opposite landscape through the glass, and also a part of the scale projected upon the landscape. The pencils of light entering the eye from the scale being parallelized by the pair of convex lenses, the scale appears to be in the plane of the object; therefore, there is no parallax, and whether the eye be moved, or the lid of the box turned for the purpose of taking the bearings of various objects, the scale always appears immovable as respects the object, so long as the lower box is not moved. Again, as the focus of the pair of lenses is equal to the radius of the scale, every space between the divisions of the scale represents its true angular value on the horizon. Con- sequently no index is required, every object having its bearing projected upon it. The instrument is mounted on a tripod stand, with parallel plates for levelling, and a rather stiff vertical joint. To take bearings of various objects as regards each other, the observer turns the lid round until he sees the object through the leaded glass; but he need not set this with exactitude; if he can see the subject anywhere in the field, it suffices. He then, holding the lid with one hand, turns the lower part of the box with the other hand, till the 0 of the scale corresponds with his object. Then he turns the upper box or lid round, so as to see each object seriatim; and he will find the bearing of each object, as respects the first, projected upon it. He can then read off these bearings as fast as an assistant can write them down. Grupp—A Circumferentor. 145 If desired, a magnetic compass can be fixed to the lower box; and then all his bearings can be taken with reference to the magnetic meridian. A striking advantage of this form of instrument is that there is not the same necessity for accuracy of mechanical fitting as in the case of the ordinary forms of measuring instruments; for instance, a slight looseness in the vertical spindle, which is pur- posely left very free in order that it may be set without the slightest danger of moving the lower box, will not produce any error in the readings, because a shake or loss in this part affects equally the object observed and the scale projected upon it, but does not affect the accuracy of the superposition of one upon the other. Plate XI. represents the instrument in its complete form, mounted upon a tripod stand. It will be seen that the whole instrument can be turned with its central axis into a vertical or horizontal position, so that vertical angles can be taken as well as horizontal. [146.4 XV. A NEW FORM OF POSITION-FINDER FOR ADAPTATION TO SHIPS’ COMPASSES. BY SIR HOWARD GRUBB, F.R.8., Vice-President, Royal Dublin Society. (Prate XII.) [Read, NovemBrr 17; Received for Publication, NovemBEr 20, 1903 ; Published, FEBruary 10, 1904.] Tris instrument possesses some advantages over the ordinary form. The figure (p. 148) is a section showing the construction. Plate XII. is reproduced from a photograph of the instrument itself. The purpose of the instrument is to obtain from a ship’s deck, with a moderate amount of accuracy, the magnetic bearing of some landmark or vessel which is in sight. It is not an operation that can be effected with great exactitude, as it is generally taken on a vessel in motion, and can only be correct for the precise moment at which it is taken. It is usually a somewhat difficult ‘observation, more particularly if the vessel be rolling in a heavy sea. The ordinary construction consists of a framework which is laid upon the covering-glass of the binnacle, and centred upon it by means of a little pin which fits in a hollow ground in the centre of the glass cover. ‘This frame supports a piece of tube mounted at a convenient angle, on looking through which a portion of the divided compass-card, which is opposite the tube, is seen through a lens, as well as a pointer, mounted across the tube, to form an index. At the upper end of the tube, on a swivel, a prism is mounted ; and by turning a button this prism can be brought into such a position that a portion of the landscape or horizon can be seen by reflection in it. If now the eye be so placed that one-half the pupil be used to view the landscape through this prism, and the other half to view the card and pointer, a coincidence can be made between the three objects. Proc. R.D.S., N.S., Vol. X. Pratm XII. = — = a ImpRoveD PosiTion-FINDER. dicen serene res en Re, re : = "i rs er =H : : E i ; Gruspp—A New Form of Position-Finder for Ships’ Compasses. 147 The whole instrument is then turned till the image of the particular landmark, whose bearing it is desired to take, coincides with the pointer; and then the division on the card which is seen to correspond with the pointer is noted as the bearing of that landmark. If the vessel were absolutely steady, and the eye of the observer quite constant in position, such an observation could be made with sufficient accuracy ; but the construction of the instrument is such that it is very difficult to obtain even moderately correct results, except when the above conditions exist. The pointer, the compass-card, and the image of the landscape, all of which have to be superposed, are, of course, at different distances; and no two can be seen distinctly at the same time; while if the eye be not kept absolutely fixed (a difficult thing in a choppy sea), there will be a considerable amount of parallax and . consequent error. By employing the same principle of construction as used in my gun-sights and geodetical instruments, the following advantages are obtained :— 1. The object on landscape or on horizon is seen erect, and not, as in the old form, inverted, which constantly leads to mistakes. 2. The image of the divided are is formed (by the action of the collimating lens) in the same plane as that of the landscape; and therefore there is no parallax, nor any possibility of error arising from the same, nor necessity to keep the eye steady in one fixed place. 3. Inthe old instrument two coincidences had to be made: the first between the object and the pointer; the second between the pointer and the division on the compass-card. In the new instrument there is no pointer or index; but the divisions on the card itself are seen projected on the landscape, and the particular division which falls upon the object is the bearing of that object. 4. As the collimating lens is made of a focus equal to the semi-diameter of the compass-card, the degree-divisions on the card correspond to degrees on the horizon; consequently it is not necessary (as in the old form) to set the instrument on the binnacle with the pointer exactly coinciding with the object (another difficult operation in a rough sea). Ii the object be anywhere in 148 Scientific Proceedings, Royal Dublin Society. the field of view—say, even two or three degrees out of the centre—the particular division on the card whichis seen imprinted on the object still gives its correct bearing. Plate XII. shows the appearance of the instrument in its complete form. I NU) il ) SD = Y Ss Os ae | ie pail a lr Compass Cara a, Piece of parallel glass coated on its upper side with sulphide of lead. 3, Silvered glass mirror. c, Frame carrying tinted glass to reduce brilliancy of image of land- scape if desired. d, A lens whose focus is equal to the radius of the compass-card S, f; Plain glass window. pik 4 XVI. AN IMPROVED SIMPLE FORM OF POTOMETER. By G. H. PETHYBRIDGH, Pua.D., B.Sc. [Read, Novemper 17; Received for Publication, DEcEMBER 18, 1903; Published, Fepruary 13, 1904.] In view of the demand which exists for simple forms of apparatus for use in the study of plant-physiology, the following account of a form of potometer suitable for studying the action of various external circumstances on the rate of transpiration may be of service to those interested in this subject. Most of the forms of potometer described in the text- books are complicated to arrange, and inconvenient to remove quickly from place to place. This applies, for instance, to the form described and figured by Darwin and Acton,’ where it will be seen that, in addition to the potometer proper (for which a special form of U tube has to be made), a retort-stand with two clamps as well as two blocks of wood are required to complete the apparatus. Moreover, I have found this form of potometer especially dis- advantageous, from the fact that, owing to there being a constant pull of some twelve to eighteen inches of water on the cut surface of the leafy shoot, unless the pull exerted by the transpiring shoot is considerable, air is drawn into the limb of the potometer from the intercellular spaces in the shoot, so that its cut surface soon comes to be standing not in water, but in air. A very simple form of potometer has been described and recommended, consisting merely of a wide-mouthed bottle, pro- vided with a double-holed rubber cork. Into one of these holes the leafy shoot is inserted, and into the other an L-shaped piece of glass tubing of narrow bore, the long limb of the L being horizontal. On filling the bottle with water to the brim, and inserting the cork, the surplus water is forced out through the glass tube. On the leafy shoot commencing to absorb water, and I «¢ Practical Physiology of Plants.’’ Exp. 92, fig. 15, p. 80. 2nd Edit. 1895. SCIENT. PROC. R.D.S., VOL. X., PART II. N 150 Scientific Proceedings, Royal Dublin Society. transpire, the water in this horizontal tube is withdrawn into the bottle; and the rate of its withdrawal can easily be determined by noting the time occupied by the water in receding from the open end of the tube to a given mark on it. On reaching this mark, by gently pushing the cork somewhat more firmly into the neck of the bottle, the water can be again made to reach the open end of the tube, and thus a second determination can be made, and soon. The objections to this form of ap- paratus are (1) the comparatively few read- ings that can be taken, owing to the fact that, to ensure water- and air-tightness, the rubber cork has to be pushed in nearly as far as it will go at the outset; and (2), if left for even a comparatively short time, the supply of water in the tube becomes exhausted, air enters the bottle, and hence, before starting fresh readings, it is necessary to remove the cork, fill the bottle with water, and re-adjust.' Tt occurred to me that both of these ob- jections could be done away with by intro- ducing a tapped thistle-funnel into the bottle, by which water could be let in to take the place of that removed by the shoot, and which could, at the same time, serve as a tempor- ary reservoir during the time in which no observations were being made, so that no air should enter the bottle.’ In its final form, my potometer worked itself out into that shown in the accom- panying figure (fig. 1). A calcium chloride tower is provided at the top with a double- iw it 1 Hall, Annals of Botany, 1901, p. 558, describes and figures a somewhat similar form of apparatus, but with a three-holed cork, the third hole being provided with a wooden rod which can be gradually pushed into the bottle so as to force the water back into the capillary tube. 2 Since this paper was read I find that Farmer has also recently made use of the tapped thistle-funnel for this purpose. Ref. in Bot. Centralblatt, Dec. 1st, 1903, p. 535. PretuysripGeE—An Improved Simple Form of Potometer. 1651 bored rubber cork. Into one of the holes of this (that in which a glass rod bearing the letter A is shown in the figure), the leafy shoot is inserted ; the other carries the tapped funnel. The lower outlet is also furnished with a rubber cork, through which passes an L-shaped glass tube of narrow bore, with the longer limb of the L vertical, and suitably supported about half-way up by means of a wire fastened to the neck of the tower. Fastened to this tube is a paper scale, which is a convenience in reading ; but which may be dispensed with, and file or other marks on the tube substituted in its place. It will be noted that the narrow- bore tube is of the same height as the funnel, so that when filled with water (as the apparatus is at the start of an experiment), and the tap turned on, it forms one limb of a U tube. As transpiration proceeds, water is absorbed by the cut end of the shoot, and its place is supplied by water from the fun- nel and from the narrow-bore tube, so that the level of the water in these slowly sinks. On turning off the tap, however, water can only be withdrawn from the narrow-bore tube, the level in which consequently sinks more or less rapidly according as to whether transpiration is rapid or otherwise. By means of this apparatus then, the chief features of which are its compact- ness, the ease with which it can be moved about, and the fact that no specially constructed tube is required, the broad effects of various external conditions, such as heat and cold, light and shade, draughts and still air, dry and moist air, &c., can be very conveniently studied and re- corded by noting the time taken by the column of water in falling through a given distance in the tube in each case. It should be noted that, before each fresh experiment, the level of the water should be adjusted to the original starting-point in the narrow-bore tube by means of the tapped funnel, since, owing to differences in water-pressure, a fall of, say, 1 cm. in the upper part of the tube is not strictly comparable with a fall of 1 cm. near the bottom of the tube. Expense may be saved by substituting for the tapped opie N 2 152 Scientific Proceedings, Royal Dublin Society. funnel, which costs about half-a-crown, an ordinary thistle-funnel costing three halfpence. A piece of glass rod is pulled out in the Bunsen flame so that its end tapers somewhat. By means of a little emery powder and turpentine, this can be quite easily ground, so as to form a kind of long-handled stopper to the bottom of the thistle-funnel, thus forming a convenient substitute for the stop- cock, although the adjustment of the level of the water in the narrow-bore tube to a given mark is not quite so easily carried out with this arrangement (as shown in fig. 2, p. 151, the stopper B being held in its place by means of wires fastened across the top of the funnel) as with the tapped funnel. 7 BS XVII. WILLOW CANKER: PHYSALOSPORA (BOTRYOSPHAERIA) GRHGARIA, Sacc. By T. JOHNSON, D.Sc., F.L.S., Professor of Botany in the Royal College of Science, and Keeper of the Botanical Collections, National Museum, Dublin. (Puates XITI.-XV.) [ Read, Decrmprr 15; Received for Publication, DecemBErR 18, 1903; Published, Marcx 26, 1904.] As long ago as the autumn of 1899, I received through the Con- gested Districts Board, from the osier-beds at Letterfrack in Connemara, specimens of rods called “‘ black mauls,”’ a commercial variety of Salix triandra, L., which had been rendered useless for basket-making. The rods broke in two owing to the presence, at one or more spots on the rod, of canker-spots. These spots are easily recognisable externally (Plate XIII., fig. 1), and may reach inwards to the pith (Plate XIII., fig. 2). They are weak spots, and cause the rod to snap in two at the least attempt to bend it. The skin of the rod at the spot looks as if it had been scorched ; it is dried up, turns brown, and becomes cracked by the protrusion of very small black specks (Plate XIV., fig. 4); later the cracked skin peels off, more or less; the inner part of the stem becomes exposed, the “cortex”’ broken up, and the hard bast appears as loose, thread-like strips, sometimes accompanied by a fissure in the disorganised wood reaching to the pith. Microscopic examination shows that the canker-spots are the external signs of the permeation, through and through, of the rod by the branching threads of a fungus of which the black specks just mentioned are the fruits. It was not until the autumn of this year that an opportunity was afforded me of seeing to what extent the disease was prevalent in the osier holts, and of obtaining, on 154 Scientific Proceedings, Royal Dublin Society. the spot, some idea as to the cause of the trouble. I was the more interested in the question as the pest was a source of loss to the well-known basket industry at Letterfrack which Miss 8. Sturge had started for philanthropic reasons, and to which she had given some seven years in teaching the boys the trade, and in making the industry a commercial success. There are some twelve acres of osiers planted, some at Letterfrack, but the greater part at Rock- field, a mile nearer Clifden. JI found cankered rods at both centres, though much more common at Letterfrack, and saw much to support the impression I had formed that the disease was actually in the sets first planted, and imported from England five or six years ago. This impression was strongly supported by the microscopic examination of cankered rods from the original source of supply in England, which I found to be suffer- ing from the same disease. It is possible to trace the disease from the set to the canker on the rod. The tissue of both set and rod is discoloured and disorganised. The cambium on the eanker side of the rod is killed, and the pith also shows the effects of the fungus both above and below the canker-spot. Microscopic examination also shows the fungal hyphe present. A canker in the willow, due to Melampsora allii-fragilis, Klebahn, a fungus indicated by orange-yellow spots on leaf and stem, has been recently described in England. I satisfied myself, by examination of some of this English ‘‘ Melampsora”’ material, that the canker I am describing in the Irish and the connected English rods had nothing in common with this Helampsora canker, though Melam- psora does occur in the Irish willows, chiefly in their leaves, and occasionally causes a rod-canker. In estimating the loss to a crop by the attacks of a disease, it is necessary to take into account, not only the damaged plants before one’s eyes, but the missing plants which might have been present but for the ravages of the disease. This feature in a disease is very strikingly illustrated in the beds: many of the sets have died completely ; others have a few feebly developed rods; others have some healthy rods with cankered ones on the same set. One field of osiers at Rockfield was almost a complete failure. The impression I formed was that, while the sets planted were diseased when put into the ground, the conditions of cultivation of the rods increased the trouble, and gave the fungus JoHnson— Willow Canker. 155 an opportunity of asserting itself more fully. One cause of failure is illustrated by Plate XV., fig. 2. The willow is a surface-rooting plant, and in planting, the sets, 12-13 inches long, should be put into the ground in a sloping direction, not upright, as was done in most of the planting at Letterfrack. Roots do not form on the lowest part of the rod if too far into the ground; the rod then remains much thinner than the rooting, more vigorous upper part. The land used for planting at Letterfrack was raw bog. This _ needs thorough draining and suitable manure. The effects of insufficient attention to these two important points are clearly observable in the beds. Again, the best osier-cultivators insist on the necessity of cleanliness of the ground. Weeds, they say, are fatal to the growth of the sets, and should be rigorously kept under. At Letterfrack the weeds have got the upper hand; and some of the plots are full of rank grasses and other weeds. At Rockfield I also saw hundreds of bundles of rods stored green for several years past, full of disease, and now, no doubt, spreading contagion. They should have been burnt when first found useless. A. too wet, poor, peaty soil would distinctly favour the canker disease once in possession of the rods, or would render otherwise healthy ones liable to fall a prey to the attacks of the fungus. The black specks in the canker-spots prove to be of three kinds, dis- tinguishable partly by their contents, partly by their size and shape. ‘The specks are confined to the blisters, and are often found aggregated together, so that three or four of them form one compound common speck, divided into compartments by their cellular walls, raising the host epidermis as they form, and bursting through it as one body (Plate XIV., fig. 1). All the black specks are minute, dark-walled bladders, each with a small opening or pore through which the contents, when ripe, escape into the outer air. In one kind the bladder, -76 x 3 mm., is lined throughout its whole inner surface with a layer of short cellular rods, or conidi- ophores, each carrying at its end a single, oblong, fusiform, septate conidium, 8°7 x 2°3 w (Plate XIII., fig. 3). The bladder is a pycnidium, and serves, no doubt, by the production of the conidia, for the vegetative propagation of the parent fungus. By means of these conidia, judging from analogy, the fungus reproduces itself throughout the growing season on other parts of the host, or on 156 Scientific Proceedings, Royal Dublin Society. other willow plants in the neighbourhood. The pycnidia are, from the practical point of view, sources of infection. On searching mycological literature for anything comparable, I was struck by the great similarity between these pycnidia and the ones described and figured by Prillieux and Delacroix in the canker disease of the sweet or Spanish chestnut in France. Some 300 acres of sweet chestnut grown as coppice for the supply of rods for laths and for barrel-hoops were attacked almost throughout the wood, and the value of the rods reduced quite 50 per cent. in consequence. The account these authors give agrees remarkably with that which I have given in the case of the willow—the same reduction in the yield of rods, loss of splitting and bending properties in those gathered. The authors called their fungus Diplodina castanee, Prill. et Delac.; and a name which naturally suggested itself for the Irish willow canker was Diplodina salicis. This name I found, on con- sulting Saccardo’s “Sylloge Fungorum,” had been given by Wes- tendorp to a fungus found and described by him growing on the weeping willow in Courtrai, the centre of the flax-retting industry in Belgium. Unable to see either Westendorp’s descrip- tion or his specimen, I wrote to Professor C. van Bambeke, of Ghent, who, with the greatest kindness, sent me a small piece of the type specimen as collected by Westendorp, a copy of the only figure given, and of the detailed description published by the author under the title ‘“ Cinquiéme notice sur quelques Hypoxyleées, inédites ou nouvelles pour la Flore de la Belgique.”” Comparison between Westendorp’s specimen and the Irish one shows that the two are distinct. In the Belgian specimen the pycnidia are scat- tered over the surface of the willow-stem, not collected on definite canker-spots, as in the Irish one. The pycnidia are also differently shaped, and contain much larger conidia. Kickx! places Westendorp’s species in the genus Diplodia, and gives a description, for a copy of which I am indebted to Professor Bambeke. I quote only the last few words :—“ Spores (conidia) ellipsoides, étroites, obtuses, hyalines, offrant au milieu, d’aprés. Yauteur, une cloison transversale que nous n’avons pu aperce- voir.” I have been able to satisfy myself, from the material sent, 1«« Flore Cryptogamique des Flandres ’’ (Gand, 1867), tome 1, p. 394. Jounson— Willow Canker. 157 that Westendorp was right in placing the fungus in the genus Diplodina, in which the conidia are uniseptate, or bisporous and colourless, and not, as Kickx does, in Diplodia, in which the conidia are brown. Possibly, as Kickx himself suggests may be the case, he was examining unripe material, before the cross-wall had had time to form. Tn the case of the Irish canker, in the unripe pyenidium the conidia are bisporous or uniseptate; and, had they remained so when ripe, the name Diplodina salicicola might have been used ; but when quite ripe, the conidia are, as shown in Plate XIIT., fig. 4, triseptate or tetrasporous. Hence the name Diplodina cannot be used in its original sense to indicate Diplodia-like fungi with colourless conidia. The name Septoria would seem at first sight more appropriate. Septoria is a name given to an enormous number of fungi of the group ‘“ Fungi Imperfecti,” and characterised by pycnidia containing colourless conidia, with several cross-walls. The species of Septoria are confined for the most part to the leaves of their hosts, causing leaf-spot diseases. Where the conidia are bisporous, and occur in pyenidia, asin Diplodina castanec, it seems desirable to use the name Diplodina rather than Septoria; as the name Septoria is given to leaf-parasites chiefly, and to such as have conidia with several cross-walls, I propose to call the fungus here found in the stem-canker, and provided with colourless rod-like conidia having, when ripe, three cross-walls, Tetradia salicicola. The cankers show a second kind of swelling, which is a true peri- thecium (0°130 x 0-1 mm.) differing entirely in its contents from the pyenidium just described. In this perithecium (Plate XIV., fig. 2) there rises, from the floor only, a hymenium consisting of clavate asci and filiform paraphyses. Hach ascus (Plate XIV., fig. 3) contains eight ascospores, more or less in two rows, 7.e. distichously or sub-distichously arranged. The ascospores are hyaline, continuous, and oblong, with usually an oil-drop, and often a vacuole at each end, as well as a central nucleus. Often the ascospores look asif bisporous, though staining shows they are really continuous or simple. Fortunately I have been able to get the opinion of Saccardo on the fungus, and can thus refer this perithecial stage of the fungus to Physalospora gregaria, Sacc., of which the following is a 158 Scientific Proceedings, Royal Dublin Society. description in ‘“‘Sylloge Fungorum ” (i, p. 485), and of which a figure appears in Saccardo’s “ Fungi Italici,”’ t. 482 :— “ Peritheciis dense gregariis peridermio tectis, globosis, brevis- sime papillatis atris, intus candidis, ascis clavatis, rotundatis, crasse tunicatis, breve stipitatis, paraphysatis, octosporis ; sporidiis, disti- chis, ovoideo-oblongis, 30-40 x 6-8, granulosis, guttalatisve hyalinis. “ Hab.—In ramis corticatis Pruni, Salicis, Alu, Corni... Rosse, &e., in Italia bor., Gallia, Sibirica Asiatica, Amer. Austr.” Physalospora is a member of the Spheriacee, a group of Pyrenomycete Ascomycetes, and characterised, amongst other features, by the clustered or aggregate character of its perithecia, as its name indicates. While the Tetradia conidia probably serve for the propagation of the canker-pest during the growing season, the perithecia of Physalospora gregaria represent the resting stage. In the following spring the ascospores, escaping from the asci and perithecia, germinate, no doubt, and attack the shoots of the willow as they sprout. I have, as yet, no evidence to enable me to say whether the ascospores or conidia can bore into the host through uninjured skin, or if they have their way prepared by a ‘wound caused by insects, by rubbing together of rods in wind, &e. The third form of fruiting-body occurring in the same canker as the Physalospora perithecia is shown in Plate XIII, fig. 5, and con- tains bodies of peculiar character. The hyphe in the pyenidium arise at any point on its inner wall, branch and produce colourless, bisporous, fusiform conidia, in size (12 x 4:5 4) and in structure comparable to the bisporous conidia of Diplodina salicis, Westen- dorp. Very often these bodies are intercalary, occurring in the course of the branching hyphe (Plate XIII., fig. 6). At first sight they suggest the genus Dendrophoma, one of the Fungi Imper- fecti, in which the conidia are simple colourless spores, as in Phoma, but differing from it in that they are formed on branch- ing, not simple conidiophores. In Dendrophoma the conidiophore branches are also in whorls and the conidia terminal. To include the pyenidium (0:16 x 0:14 mm.) I have just described in Dendro- phoma would need an extension of the characters of the genus; and as the conidia are larger than the Tetradia ones, I propose for this kind of pyenidium the provisional name Macrodendrophoma salicicola. JoHunson— Willow Canker. 159 One peculiar feature which appeared in several different cankers is worthy of note. After a pycnidium has emptied its contents, its floor rises up into its cavity,-and forms a second pyenidium with contents, replacing the one the cavity of which it has obliterated (Plate XV., fig. 1). Invagination is common in marine Alge, and in some fungi, where a sporangium, emptied of its contents, becomes invaded by the turgid cell below, which becomes, in its turn, a sporangium. I have not before seen invagination of a pycnidium. InFEcTION EXPERIMENTS. I have seen the canker-spots on so many different rods, all show- ing the same kind of bodies as those described, that I am fully satis- fied as to the cause of the local rottenness of therod. On July 6th, 1903, I infected, under sterilization conditions, several perfectly healthy young plants of several species of Saiz, supplied by Mr. F. W. Moore, u.n.t.a., the Keeper of the Royal Botanic Gardens, Glasnevin. On the 29th of September, while the control plants were quite healthy and normal, the infected ones at the points of infection showed signs of canker-formation, with myce- lial hyphz and pycnidia, which were too young for complete identification. As far as the experiments went, they tended to show the reappearance of the disease. PREVENTION OF THE DISEASE. To carry out experiments in the prevention of the disease by fungicides requires ground such as is provided in the Govern- ment Pathological Stations I have seen in France and Germany. In the absence, as yet, of such facilities here, I have been confined to laboratory experiments. Mr. J. Adams, 8.a., the demonstrator of Botany in the Royal College of Science, has made a number of experiments on the ascospores and conidia, treated with Bor- deaux mixture, 2 per cent.; sulphide of potash, 0:25 per cent. ; or with formalin, 0:5 per cent. solution. In each case the spores were soaked for an hour in the solution, and then cultivated in a boiled extract of willows. The formalin proved most fungi- cidal. Neither ascospores, conidia, nor the mycelium in ne willow stem, germinated after treatment with it. Field experiments are needed before one can make a definite recommendation for practical purposes. 160 Scientific Proceedings, Royal Dublin Society. Within the last month I have received specimens of cankered rods from Co. Kilkenny, through the Department of Agriculture and Technical Instruction. Microscopic examination shows that the cause of the canker is here also a species of Physalospora. SuMMARY. 1. The osier-canker, which renders the diseased rods worthless for basket-work, is caused by the ascospore-forming fungus Physalospora gregaria, Sace., which has associated with it two other stages, here distinguished as Tetradia salicicola and Macro- dendrophoma salicicola. ‘The former may be the microstylospore and the latter the macrostylospore stage of Physalospora gregaria, Sace. Were they not septate, the conidia in the Zetradia stage might be the spermatia of the spermogonium of Physalospora. © 2. Judging from analogy, all three fruiting stages are capable of infecting healthy willows. 3. The sets when planted were diseased. 4. The new habitat—poor, undrained, raw bog—and prevalence of weeds have favoured the fungus. 5. The fungus has, under the circumstances, killed off some of the sets; in some cases has caused the rods formed to be few in number and small in size; and in other cases, by forming the cankers, has spoilt them for basket-manufacture purposes. 6. The cankers are the external sign of the general permeation of the set and its shoots by the fungus mycelium or hyphe. ¢. Every care should be taken not to plant diseased sets from an infected holt. 8. The land chosen for osier growth should be well-drained, to avoid stagnant water or sour soil, and should be well-manured. Bog-land is especially poor in lime, potash, and phosphatic mineral food-materials. 9. As soon as disease shows itself, the attacked sets should be uprooted, burnt, and replaced, or the diseased rods cut to prevent the disease spreading. The ‘‘ Black Mauls” seem to be the chief sufferers from the disease in the West. 10. A weak solution of formalin, 0°5 per cent., may be used for spraying, to kill the contents of the various kinds of fruits. This is, at the best, a surface-cure for a deep-seated disease, and has not, as yet, been tried in the holt. JoHNson— Willow Canker. 161 EXPLANATION OF PLATE XIII. 162 Scientific Proceedings, Royal Dublin Society. PLATE XIII. [Nore.—All the figures except fig. 1 were drawn by Miss R. Hensman.| Fie. 1. General view of canker-spot on one-year-old rods of “ black mauls”’ (Salix triandra, L.) Drawn by Miss J. Hensman. 2. Cross-section of one-year-old rod, showing extent of canker destruction of tissues. Slightly magnified. 8. Section of pyenidium of Tetradia salicicola. x 100. 4. Triseptate conidia of Tetradia, with uniseptate conidiophore. x 440. 5. Section through a group of pycnidia of Macrodendrophoma in a canker. x 100. 6. Isolated bisporous conidia of same. x 440. Proc. kk. Dy S.No Se Volnx. Plate XIII, i‘UKarlane & Erskrme, Lith Edin® Jounson— Willow Canker. 163 EXPLANATION OF PLATE XIV. 164 Scientific Proceedings, Royal Dublin Society. PLATE XIV. [Nore.—All the figures were drawn by Miss R. Hensman.] Fic. 1. Section of canker showing perithecia of Physalospora gregaria, Sace. x 100. 2. Section through ripe perithecium of Physalospora gregaria, Sacc. x 440. 3. Isolated ascus, with paraphyses of same. x 500. 4. Canker-spot, surface-view, showing skin of rod splitting and peeling away. x 10. aocskaD.s.,.N. 5. Volex. Pilate xxiv Po ANG _L rs paper SS Be SNS —— MFarlane & Erskine, Lith. Edin® JoHNson— Willow Canker. 165 EXPLANATION OF PLATE XV. SCIENT. PROC. R.D.S., VOL. X., PART II. O 166 Scientific Proceedings, Royal Dublin Society. PLATE XV. Fic. 1. Invagination of pyenidium. Microphotograph. x 80. 2. Photographic illustration of set and rods. See text, p. 154. JEIROGs dei Daten Iasi \WOlle IX. Pyaar SOW, Mie, We ter XVIII. THE COMPARISON OF CAPACITIES IN ELECTRICAL WORK: AN APPLICATION OF RADIO-ACTIVE SUBSTANCES. By J. A. McCLELLAND, M.A., Professor of Experimental Physics, University College, Dublin. [ Read, January 19; Received for Publication, JanuaRY 22; Published, Frsruary 26, 1904. ] THERE are many methods by which two capacities may be compared, and which are fully described in text-books of Physics. When only approximate results are required, we have several methods to choose from, any of which will give a fair result ; but the problem is by no means so simple when an accurate determi- nation is required, especially if we are dealing with a very small capacity. That better methods of dealing with the determination of capacities, especially small capacities, are still required may be judged from the fact that two papers have recently appeared on the subject, one by Professor Fleming and Mr. Clinton in the Phil. Mag., May, 1903, and the other by Professor Stroud and Mr. Oates in the Phil. Mag., December, 1903. Those two papers may be taken as affording examples of the difficulty of obtaining accurate results in this work, both methods necessitating somewhat elaborate apparatus, and involving con- siderable experimental difficulties. My object in this paper is to describe a method at once simple and accurate, and suitable for the determination of capacities of any magnitude down to a few micro-microfarads, or even less. The method is based on the fact that the ionisation current that can be obtained by the use of a radio-active substance like uranium is extremely constant, and can be made so small that the time taken to charge a condenser by it can be accurately measured. This small constant current is used first to charge one condenser 02 168 Scientific Proceedings, Royal Dublin Society. to a given potential; and then a second condenser is charged to the same potential, and the time taken in the two cases observed, so that we get the ratio of two capacities by simply observing two intervais of time. The method will probably have occurred to anyone who has been using radio-active substances; but as many workers have occasion to compare capacities accurately who are not using radio- active substances, I have thought it advisable to make a few experiments showing the accuracy of the method, and showing also how small a capacity can be detected and measured by it. To use the method it is not necessary to have a supply of radium, as the title of the paper might suggest; uranium is. even better in some respects, and uranium is to be found in every laboratory. Description oF APPARATUS AND MertHop oF WoRrRKING. A and B are two insulated metal plates, one of which, B, can be joined to one terminal of a battery of small storage-cells, the STORAGE : CELLS B EARTH other terminal of which is to earth. The battery may consist of 100 or more small test-tube cells, so that B can be kept at 200 volts or higher. A. few grammes of, say, uranium nitrate are spread on a sheet of paper, and placed on the plate A. The radiation from the uranium ionises the air between A and B; and so A gradually rises in potential if insulated, supposing B to be positive. As is well known, the ionisation current thus obtained between two plates M‘CLELLAND— Comparison of Capacities in Electrical Work. 169 increases at first as the potential difference between the plates increases; but when this potential difference is made sufficiently great, the current attains a maximum, and does not further increase for further increase of potential difference between the plates. If then B is kept at a sufficiently high potential, small changes in this potential, due to the potential of the battery falling, will pro- duce no effect ; and, again, in making an observation, the potential of A need never change by more than one volt, so that there is no trouble in keeping a constant current to the plate 4d. The con- stancy of the current in the above arrangement only depends on the constancy of the radiation from the uranium; and numbers will be given to show how very constant this radiation is. The potential difference required to produce the maximum current to A will depend on the distance between A and B; but it is well to haye 200 volts available. C represents one of the condensers being compared; and F is a quadrant electrometer. D is an insulating block of paraffin, con- taining two mercury cups, a and 0, one of which is connected to earth. A connecting piece Z is shown, joining the mercury cups, and, by means of a string arrangement, L can be lifted out of the mercury cups and lowered again as desired, from a distance, so as to avoid induction effects produced by movements of the observer. As soon as Z is lifted out of the mercury cups, the plate 4, the condenser C, and the electrometer begin to charge up; and the time is observed during which the spot of light moves over, say, 100 scale-divisions. An exactly similar experiment is done with a second condenser C’ in the place of C. If the intervals of time are respectively ¢ and ¢’, we have C+e ene CONOR e where c¢ is the capacity of the electrometer, the condenser AB and the connecting wires. The capacity c can be determined in terms of, say, C, by taking an observation with C’ joined up as shown, and then an observation with C disconnected, so that only cis charged; or the capacity c may be determined once for all by comparing it in this way with a known capacity. We thus get the ratio C/C’. 170 Scientific Proceedings, Royal Dublin Society. Accuracy oF THE METHOD. The accuracy of the method obviously{depends simply on the constancy of the ionisation current, and on the accuracy with which the time-intervals are measured. Numbers are given below to show how very constant the ionisation current is. In practice it is well to screen the space between the plates A and B from air currents, as such currents, if strong, may blow away the ionised air, and diminish the ionisation current. As regards the radio- active substance used, uranium is preferable to thorium or radium, as it gives off no emanation. If radium or thorium is used, it should be in a closed vessel to prevent the emanation from escap- ing, otherwise the ionisation current will not be steady. The method involves the use of a quadrant electrometer, which to some may appear an objection to the method. The writer's experience, however, is that no sensitive scientific instrument gives less trouble in working than a quadrant electrometer, when it has once been put in goodorder. When the capacities being compared are small, no great sensitiveness of the electrometer will be required —say 60 millimetre scale-divisions for one volt with scale one metre from electrometer. When large capacities are being compared, greater sensitiveness will be necessary, unless a very large quantity of uranium is used; but there is no trouble in having an instrument one hundred times as sensitive as above. Somse EXPERIMENTS WITH THIS MetTHop. (a) We shall first give some numbers to show the constancy of the ionisation current in the above arrangement, and the accuracy with which the time required to charge any system through a given range of potential can be measured. ‘The system charged consisted of the electrometer, a capacity marked -001 microfarads, and the condenser formed of the plates between which the uranium is placed. The time taken for the spot of light to move over fifty scale- divisions was taken with a stop-watch reading to fifths of a second. A. series of seven observations was made, giving the following numbers, no observation being rejected. M‘Ciettanp—Comparison of Capacities in Electrical Work. 171 Time taken to move over 50 scale-divisions :— 99-2 seconds. OS 990 ,, 99-4, 992 ,, 99:2 ,, To, Mean, 99°23 seconds. The agreement between these numbers is no better than that usually observed in other experiments ; in fact, not as good as in many other cases. (6) We shall now give the numbers observed in a comparison of a condenser with a standard condenser, marked :001 micro- forad. We shall denote the capacity of the condenser to be measured by C, and the capacity of the electrometer and other parts of the system, by ec. The electrometer in this experiment gave a deflection of about 60 scale-divisions for 1 volt, and about 30 grams of uranium nitrate were placed on the central part of the plate -4 ; observations were taken alternately with the capacity C joined up to c¢, and with the capacity -001 microfarad joined up to ¢, giving results as follows :— 001 +¢ Ore 50 divisions in 52°6” 50 divisions in 89:5” 50 divisions in 52°5” 90 divisions in 88°7” 50 divisions in 52°2” Mean, 52°43” Mean, 89:1” Cre 8910 Therefore, 00L=e 5943" A smaller quantity of uranium was then used to determine the ratio between ¢ and :001 microfarad, as with the quantity used above the movement of the spot of light would have been too 172 Scientific Proceedings, Royal Dublin Society. rapid when only the capacity cis in use. The following are the numbers in this determination :— e+:°001 é 100 divisions in 21:9” 50 divisions in 75°8” 100 divisions in 21:8” 50 divisions in 75:7” 100 divisions in 22:2” Mean, 75°75” Mean, 21:97” e+:°001 15150 Therefore, ae ve These equations give ‘000169 microfarad ; ‘001817 microfarad. G C To give somewhat of a test of the reliability of the method, the same capacity was determined on another occasion, taking no care to use the same quantity of uranium, and, in fact, having very different ionisation currents from those used in the first ease. The following numbers were obtained, only one observation being taken in each case :— C+e “001 +¢ 50 divisions in 48:2” 50 divisions in 28-6” e+:001 00 divisions in 56°5” 100 divisions in 16°5” Calculating as before, we get e = ‘000170 microfarad ; C = :001802 microfarad. The agreement with the preceding numbers is very good, especially when we consider that only one observation was taken in each case. . (c) To show that this method is suitable for much larger capacities than those used in the preceding examples, we shall give an example in which a capacity known to be about 5 micro- farad was determined by comparing it with a standard capacity of ‘1 microfarad. For this purpose, an electrometer of the M‘Crettanp—Oomparison of Capacities in Electrical Work. 173 Dolezalek type was used, giving a deflection equal to 5300 scale- divisions for 1 volt. Observations were taken as before, first with the unknown capacity C joined up to the electrometer and the plate A, and then with the capacity -1 microfarad joined up. About 100 grams of uranium nitrate were placed on A (fig. 1), and the following numbers noted; ¢ denotes the capacity of the Dolezalek electrometer, and some apparatus that was in connexion with it :— Cre ‘l+e 50 divisions in 104:5” 100 divisions in 41°8” 00 divisions in 104:4” 100 divisions in 41:8” Mean, 104:45” Mean, 41:8” C+e 208°9 Therefore, cn none Less than 1 gram of uranium nitrate was now used to determine the ratio of c to a known capacity of 001 micro- farad, giving as follows :— c e+ :001 100 divisions in 21:0” 100 divisions in 30:5” 100 divisions in 21:2” 100 divisions in 30:0” e+:001 605 Therefore, ; =a These equations give e = :0023 microfarad ; C = :5089 microfarad. A repetition of this determination gave as before, with smaller capacities, an equally consistent result. (¢) A careful experiment was now made to find how small a capacity could be detected and measured by this method. To do this a condenser of the following type (fig. 2) was arranged :— AB is a long wide tube, 7:90 cms. internal diameter; ad is another tube fixed, as shown, to be coaxial with AB. In ad a third cylinder cd slides, fitting closely into ab, the external diameter of ed being 1:94 cms. AB is joined to earth, and ab (and cd) 174 Scientific Proceedings, Royal Dublin Society. connected to the Kelvin electrometer. The capacity of the electro- meter, the condenser as arranged (fig. 2), and joining wires is determined by comparing it with a standard capacity of 001 microfarad. A careful series of observations is then taken, with cd in its above position, using a suitable quantity of uranium nitrate. B dl b = @ A Fig. 2. Then the tube cd is moved 8:01 cms. further into AB, care being taken not to displace AB or ab. A vernier was attached to cd working in a slot in aé,‘so that the distance through which cd was displaced could be accurately measured. A second series of observations was then made with cd in the new position, keeping the same uranium as before. We have thus the data for deducing from the experiments the increase of capacity produced by the movement of cd. ‘This increase of capacity can also be accurately calculated from the formula l Bi) 2 log — since the effects of the ends are eliminated by the arrangement used, / being the distance cd is moved, and 1, and r, the radii of AB and cd respectively. We can thus estimate the value of the method for measuring very small capacities. The numbers observed were as follows :— (1) Finding the capacity C made up of the condenser described (fig. 2), the electrometer, and connections, a 001+ ¢ 100 divisions in 39:7” 50 divisions in 117°8” 100 divisions in 39°6” 50 divisions in 118-1” 100 divisions in 39:5” 50 divisions in 117°8” Mean, 39:6” Mean, 117-9” C+:001 285°8 Therefore, Tai WT WIBoee or, C = :000201 microfarad ; or, © = 201 micro-microfarads. M‘CieLLAnD— Comparison of Capacities in Electrical Work. 175 (2) To find the small change in capacity a when cd has been moved into its second position. In first position :— 100 divisions in 59-0” 100 divisions in 59°5” 100 divisions in 59:1” Mean, 59°20” In second position :— 100 divisions in 60°5” 100 divisions in 59:8” 100 divisions in 60-0” Mean, 60°10” C+a 60-1 Therefore, GO = 590" and C = 201 micro-microfarads ; a = 3°05 micro-microfarads. Calculating a from the formula L (Oh SS , 9 2 log — Te where 7 = 8:01 cms., r, = 3°95 cms., T, = ‘97 cm., 2:85 electrostatic units 3°16 micro-microfarads. We get, therefore, 3°16 by calculation, and 3°05 by experiment. we get a The method is therefore quite capable of detecting;and measur- ing with considerable accuracy a capacity of 1 micro-microfarad or even less. Discussion oF THE ADVANTAGES OF THE MeTHOD. It is not necessary to compare this method in detail with the many other methods used in comparing capacities; it will be sufficient to point out a few leading facts. 176 Scientific Proceedings, Royal Dublin Society. Capacities may, of course, be compared by the electrometer without any use of radio-active substances by charging the un- _ known capacity to a potential which is measured by the elec- trometer, and then sharing the charge with a known capacity, and again measuring the potential. The method of working is not, however, as accurate as that described above, especially when the capacities are small. Capacities are often compared by charging them to the same potential, and discharging them through a ballistic galvanometer. The galvanometer deflection must be accurately read, and a cor- rection applied for damping—observations which cannot be made with the accuracy with which we can compare two intervals of time. Again, when the capacities are small, they must be charged or discharged through the galvanometer a great number of times per second, which requires carefully constructed apparatus to enable the number of charges to be accurately known. In addition, it is somewhat difficult to be certain that the apparatus is working properly; for example, an error might arise through faulty insulation, and escape detection. The method of De Sauty is free from many of the objections mentioned above; but others might be urged against it, and espe- cially that it can be of little use when the capacities are very small. One of the chief advantages of the method described in this paper is that, from the nature of the apparatus used, it is scarcely possible for any serious source of error to come in without detection ; a faulty insulation, for example, can easily be guarded against. The only quantity requiring to be measured is an interval of time, which can be done with great accuracy. The ionisation produced by the uranium keeps very constant throughout the time required to make a determination; and there is no other quantity that requires to be kept very constant. The potential of the battery joined to one of the plates between which the uranium is placed may vary considerably between the observations, and produce no effect, provided the potential is sufficiently great. The only objection that seems likely to be made to the method is the fact that it employs a quadrant electrometer, the use of which in ordinary laboratory work has hitherto been discouraged. As stated above, the writer sees no reason for the reluctance to use M‘Crieittannp— Comparison of Capacities in Electrical Work. 177 electrometers when their use can be avoided by means of galva- nometers and other, sometimes complicated, apparatus. Some of the lines of research in recent years have necessitated an extensive use of quadrant electrometers, with the natural result that they have been greatly improved ; and whatever reasons there may for- merly have been for avoiding the use of electrometers, these reasons have now entirely disappeared. rae 7 XIX. PRELIMINARY NOTE ON THE ACTION OF THE RADIATIONS FROM RADIUM BROMIDE ON SOME ORGANISMS. By HENRY H. DIXON, Sc.D., Assistant to the Professor of Botany, University of Dublin; and J. T. WIGHAM, M.D., Assistant to the Lecturer in Pathology in Trinity College, Dublin. (Prares XVI.-XVIIL.) [Read, Decemper 15; Received for Publication, DrcemBEr 18, 1903 ; Published, Marcu 12, 1904.] Last autumn one of us began experimenting on the effect of these radiations on plants. The experiments were made on seed- lings of Lepidium sativum and on Volvow globator. They were planned so as to find out if the radiations would act as a stimulus to evoke growth-curvatures, or if they would exert a directive action on the motion of a motile organism. At the same time, abnormal and pathological effects were looked for. The experiments carried out on the seedlings were as follows :—— Experiment I.—100 seeds of Lepidiwm sativum were uniformly distributed over an even surface of moist quartz sand. After germination had taken place and the radicles were just visible, a sealed glass tube containing 5 mgrs. of radium bromide was set over the central seed at a distance of 1 em. from it. In order to remove the disturbing effects of uneven illumination, and to render the seedlings as sensitive as possible to the radiations, they were kept in the dark, except for the feeble light emitted by the radium bromide itself. Thus arranged, if the seedlings were positively radiotropic—e.e. tended to turn to the source of the radiations—the central plants would grow vertically upwards, while those nearer the periphery of the sand would incline towards the centre. If, on the other hand, they were negatively radiotropic, they would all be deflected from the radium-tube to a greater or less degree, according to the vigour of the response. At the end of a few days the seedlings had grown up round Dixon & WicHAm—Radiations from Radium Bromide. 179 the tube, but no curvatures were apparent. The seedlings, how- ever, within about 1 cm. radius, were slightly less grown than their fellows; but this difference was by no means marked, nor did they appear unhealthy or in any way abnormal. At the end of ten days, the difference in height of the seedlings close to the radium, and of those further removed, was more noticeable; and while the average height of the peripheral plants was 51 mm., that of those within the 1 cm. radius was 44 mm. The radium-tube was then removed, and the seedlings exposed to daylight. The central plants still remained behind the others in point of growth for the few days during which their develop- ment was watched. Experiment I1.—Seeds similarly treated and similarly exposed to the radiations showed, three days after germination, the same slight retardation of growth. In this case it was noticed that the number and development of the root-hairs of the retarded seedlings were considerably inferior to those of the others. But otherwise the retarded individuals seemed healthy. Microscopic examination of their cells did not reveal any perceptible difference from those of the unretarded plants. Experiment III.—In order that the radiations might act on the seeds throughout germination, dry seeds were distributed over moist sand. ‘The radium-tube was supported so that only the thickness of the glass (about 0°5 mm.) intervened between it and the test of the central seed. Notwithstanding this close proximity, the central seed and its fellows had protruded their radicles on the second day after sowing. As before, a slight retardation of growth was observed in the subsequent development of the central seedlings, but no injuries could be made out. Further, there were no curvatures induced by the radiations. In order to test a motile organism for radiotropic response, Volwox globator was selected as suitable material. Several hundreds -of this colonial protococcoid were used in the experiment. These velocity-coefficients provide us with exact numbers wherewith to compare the relative reactivities of the different alkyl iodides, as measured in alcoholic solution by silver nitrate. The following table gives the values of these coefficients as deter- mined in a0 equivalent molecular solution at 24:5° for the iodides of methyl, ethyl, n-propyl, x-butyl, isobutyl, and isoamyl in both ethyl and methyl alcohol as solvent. TasLe 2.—Reactivities or ALKyL JopIpEs, AS MEASURED BY AgNO, 1n Atconoric SoLurion. Toute. ron < 1 | *ycou X10 | *ycon/ Axton | Mery nie aie 93-5 180 1-92 Hihyh ye) i 220-0 442 2:00 n-Propyl, . 5 98-4 226 2°29 n-Butyl, . : 68°6 145 2-11 Isobutyl, . : 13°8 — — Isoamyl, . ; 56°5 _ —_— SCIENT. PROC. R.D.S., VOL. X., PART II. Q 198 Scientific Proceedings, Royal Dublin Society. We see that the reactivity is uniformly about twice as great in methyl as in ethyl aleohol. This higher velocity in methyl as compared with ethyl alcohol has been previously observed by Menschutkin, Carrara, and others, and may be connected with the superior dissociating power of the former. On examining the results obtained in ethyl alcohol, they appear to present a very extraordinary irregularity. If we plot velocity- coefficient against mass of alkyl radical, the nature of this apparent irregularity is at once brought out. Methyl and isobutyl iodides are seen to lie off the “curve,” 7.e., their reactivities appear to be abnormally low. ‘This result is particularly remark- able in the case of methyl iodide, for in nearly all previous kinetic investigations of the reactivity of the alkyl iodides, methyl iodide has been characterised by a pre-eminently great reactivity ; and this behaviour may indeed be said to characterise the lowest member of a homologous series, just as the lowest homologue of a natural family of elements stands out from the others. The low reactivity in the case of isobutyl iodide need not surprise us, for most of the iodides compared above possess a normal chain. The intimate relation between the structure of the alkyl radical and the reactivity of the iodide is strikingly shown in the case of isopropyl iodide. This substance is not included in the above list, because, owing to its enormous reactivity, it was not possible to determine the velocity-coefficient in 4 solution at 245°. By employing = — equivalent solutions of isopropyl iodide and silver nitrate, the velocity of the reaction was sufficiently slowed down to permit of accurate measurement. Thus at 17°, the value of & was found to be about 2000 x 10°. Considering that the velocity of a chemical.reaction is increased two or three times by a rise of temperature of 10°, we may say that isopropyl iodide is at least seventeen times more reactive than ethyl iodide, as measured by silver nitrate. Unlike the cases of acids and bases (and, to a less degree, salts), it is not in general possible, however, to construct tables of the relative reactivities of neutral organic substances—even of substances of such a simple type as the alkyl iodides—which shall be independent of the reagent and of the particular reaction Donnan—On the Reactivity of the Alkyl Iodides. 199 employed. This is well shown by comparing the above results with those obtained in previous investigations. In the following table are given the relative reactivities of some alkyl iodides as measured by the velocity of their reaction with sodio-aceto-acetic ester in ethyl alcoholic solu- tion.! TABLE 3.—WISLICENUS EXPERIMENTS. Iodide. Relative Reactivity. Methyl, . : : : 196 Ethyl, . : : : 21 n-Propyl, ; : . 5 Isopropyl, . 3 : 1:9 Isobutyl, : : ‘ 1 Tertiary Butyl, . : Very small. Ally See : : : > 784 These figures show the eminent reactivity of methyl iodide as compared with other saturated aliphatic iodides. Isopropyl iodide is not distinguished by any special reactivity, and falls more or less into line in the curve connecting reactivity with mass of the alkyl group. The enormous reactivity of the unsaturated allyl iodide;forms a striking feature of Wislicenus’ results. In 1890 Menschutkin’ investigated the velocity of combination of the saturated aliphatic iodides with triethylamine in acetone solution at 100°. The reaction RI + N(Bt), = NR (Et), I was found to obey the bimolecular velocity-equation. The relative reactivities, as measured by the velocity-coefficient, are given in the subjoined table. 1 Wislicenus, Lieb. Ann., 1882, vol. 212, p. 239. 2 Zeitschrift fur Phys. Chem., vol. 6, 1890, p. 41. 200 Scientific Proceedings, Royal Dublin Society. TasLE 4.—MenscHuTKin’s EXPERIMENTS. Todide. Relative Reactivity. Methyl, . 5 : : 1140-00 Ethyl, . 5 : : 10°10 n-Propyl, ; 5 : 1:98 n-Butyl, : : ‘ 1°38 n-Heptyl, 2 6 ; 1:08 n-Octyl, : ; : 1:00 Here, again, we see the great reactivity of methyl iodide and the rapid fall of reactivity with increase of mass of the alkyl group. in the three lower homologues. Substantially the same results were obtained by Hecht, Conrad,. and Brickner’ in their study of ether-formation from the alkyl iodides and sodium alcoholate in dry ethyl alconol at 30°. Williamson’s reaction RI + Na: OHt = R:O- Et + Nal was also found to obey the bimolecular velocity-equation ; and the following table gives the relative reactivities as determined by the velocity-coefficients (also referred to the reactivity of n-octyl iodide as unity). TasLe 5.—ExpEriments oF Hecut, Conrad, AND BRUCKNER. Todide. Relative Reactivity. Methyl, . : ‘ : 61°72 Ethyl MEL Oho 4:87 n-Propyl, 5 : : 1°71 Isopropyl, . : : 0:92 n-Heptyl, . , : 1-04 n-Octyl, ye ali 1:00 1 Zeit. fur Phys. Chem., vol. 4, p. 278. Donnan—On the Reactivity of the Alkyl Lodides. 201 So far as the general order of reactivities is concerned, these results are in very good agreement with those obtained by Menschutkin. It may be noted that isopropyl iodide is characterised by a relatively low reactivity. Tf relative reactivity be plotted against mass of alkyl radical, the general resemblance between the results of Menschutkin, and of Hecht, Conrad, and Briickner, is found to be very striking. Considering the similarity of the results obtained in these three totally different reactions (i.e. with sodio-aceto- acetic ester, triethylamine, and sodium alcoholate) and the— in two main respects at all events—widely divergent order of reactivities as measured by silver nitrate, there is good ground for the belief that, in the latter case, the reaction is intimately associated with some special function or state of the alkyl iodide molecule. The number and comparative complexity of the pro- ducts of the reaction afford further confirmation of this. Whether these results can be explained by Net’s dissociation-hypothesis, or indeed by any dissociation-hypothesis, can only be decided by further detailed investigation, a portion of which has been already carried out without, however, yielding any perfectly decisive results so far as the intimate mechanism of the reaction is concerned. As is well known, the alkyl iodides turn yellow or brown when exposed to light, the coloration of the solution being due to free iodine. Possibly this reaction is connected with the dis- sociation-equilibrium :— R: CHI < R- OH + HI, the hydriodic acid being oxidized by the oxygen of the air usually present. The latter reaction is known to be catalytically accelerated by the presence of light. However that may be, an interesting relation between the rate (and extent) of this production of free iodine and the corresponding velocity-coefficients (as measured by silver nitrate) has been established. 50 > solutions of the alkyl iodides in dry alcohol were put into tightly-corked test-tubes and exposed to uniform diffused daylight. On the following day, the solution of isopropyl iodide showed a faint yellow coloration. The other solutions became coloured in due course in the relative 202 Scientific Proceedings, Royal Dublin Society. order of their reactivities as measured by silver nitrate, with the single exception of methyl iodide, which appeared to possess a rate of decomposition intermediate between isopropyl and ethyl iodides. After six months the colorations, as roughly judged by eye, were as follows :— Isopropyl iodide : OLS ibsess ena, Methyl iodide ‘Ethyl iodide n-Propyl iodide Intense yellow. n-Butyl iodide Pale yellow. Isoamyl iodide Isobutyl iodide, . . + Colourless. If this list be compared with the table of reactivities, as given on page 197, the general parallelism is unmistakable. The exceptional position occupied by methyl iodide is very peculiar, considering its relatively low reactivity. Roya Coitece or Science, Dustin. February, 1904. [e203 ] XXII. ON THE STRUCTURE OF WATER-JETS, AND THE EFFECT OF SOUND THEREON. BY PHILIP E. BELAS, Science Scholar, Department of Agriculture and Technical Instruction for Ireland, Royal College of Science, Dublin. [COMMUNICATED BY PROFESSOR W. F. BARRETT, F.RB.S.| (Prares XTX.-XXIT.) [Read, Marcu 15; Received for Publication, Marcu 18; Published, May 12, 1904. | Tue circumstances under which the disintegration of a liquid jet takes place have attracted the attention of many philosophers. Early in the last century Savart, in a series of classical re- searches, investigated the subject; and, following him, Plateau, Magnus, Lord Rayleigh, and others have, in their turn, discovered and explained many beautiful and complicated phenomena. During the course of my work, as a third-year student of physics, I had occasion to repeat some of these experiments; and I here propose to give a brief account of them, together with some additional observations of my own, the whole illustrated, as far as possible, by means of instantaneous photographs. The observations were made, and the photographs taken, in the Physical Laboratory of the Royal College of Science, by kind permission of Professor W. F. Barrett, r.r.s., to whom I take this opportunity of expressing my thanks for the suggestions and facilities he afforded me in the work. If we observe a jet of water flowing from a narrow orifice, we see that it may be divided into two parts—(1) a clear and unbroken column; (2) a turbid portion. The latter owes its troubled appearance to its being in reality a rapid succession of drops, which move too rapidly for the eye to distinguish them so long as they are viewed by continuous light. 204 Scientific Proceedings, Royal Dublin Society. On viewing the jet by intermittent light, such as that given by a rotating disc with slots in it, when interposed between the eye and the jet, or by the sparks from a Leyden jar charged from an induction coil, we can see the true shape of the drops, and discern their mode of formation. The device I adopted was to put the spark-gap behind a con- densing lens, in front of which the stream of water flowed. By means of a second lens an image of the stream was formed on a ground-glass screen, which was very brilliant when viewed from behind. If the screen were replaced by a sensitive plate (cutting off extraneous light), a photograph could be obtained of the jet at any instant by allowing a single spark to pass; this can easily be done by moving the hammer of the coil by hand. These photographs afford a very convenient way of studying the jet. Towards the lower part of the clear column alternate swellings and contractions may be seen, while at the extremity a drop forms which extends itself horizontally and leaves the column with its major axis horizontal; not, as is generally thought, vertical. There is then left a slender neck of liquid, which next detaches itself, and, gathering together by surface-tension, forms a smaller drop. (Plate XIX., fig. 1.) The larger drops as they fall do not at once assume the spherical form, but execute vibrations, being alternately elongated and compressed in the direction of their axis of symmetry. The time of vibration 7, of course, depends upon the nature of the fluid and the size of the drop. Lord Rayleigh gives this formula *:— where V = volume of the vibrating mass, p the density of the liguid, and Z' the surface-tension. The time of vibration of a drop of water 2:5 cms. in radius is very nearly 1 second. There is nothing very regular in the appearance of such a jet; the drops are moving with different velocities ; frequent collisions occur, giving rise to the fine spray that may be seen in the lower part of the stream. If a sudden blow be given to the stand 1See Lord Rayleigh’s ‘‘Scientific Papers,”’ vol. i., p. 392. Brtas—On the Structure of Water-Jets. 205 supporting the nozzle, a long portion of the stream may be detached. (Plate XIX., fig. 2.) If now, instead of allowing the column to break up arbitrarily, we impress upon it vibrations of a regular character, a marked change takes place in itsappearance. Placing a sounding tuning- fork on the stand, the first thing to be noticed is that the jet begins to separate into drops a good deal nearer the orifice, while lower down (if the conditions be favourable) it assumes a beautiful wavy outline, consisting of perfectly regular swellings and contractions. On removing the fork from the stand, the jet regains its former appearance, though the fork may be vibrating strongly, showing that the vibrations transmitted through the air have little or no effect. Let us now consider the cause of these swellings. If swellings are to be found in a jet, the regularity in the separation of the drops must not only take place in such a manner that (1) all the drops are equally great, but (2) the time that elapses between the formation of any two of them must remain constant. For it is only under these conditions that all drops on arriving at the same part of the stream are in the same phase. At the middle of a swelling they are drawn out to the greatest extent in a horizontal direction ; and in the space between two swellings, they are most elongated vertically. It is therefore on account of their assuming these different diameters that they produce the appearance referred to.’ On examining the photographs, we can see clearly what has taken place. A large drop is cast off elongated horizontally ; next follows a small one, formed by the narrow neck of liquid; then a large one; but, by the time the second large drop is cast off, the first has swung through half a vibration, and is now elongated in a vertical direction. (Plate XX.) This regular alternation of drops is confined chiefly to the upper portion of the stream. Lower down, collisions occur between the large and small drops, while at the lowest part the small drops have disappeared, and the large ones have all become more or less spherical, the vibrations having died out. (Plate XXII.) In a jet possessing no swellings, the detached masses are not 1 Magnus, ‘‘ Hydraulic Researches,’’ Phil. Mag., 1859, vol. xviii., p. 175. 206 Scientific Proceedings, Royal Dublin Socety. uniform in size, nor do they separate at equal intervals. Hence all drops arriving at the same part of the stream are not in the same phase, and consequently they do not produce the appearance of swellings. ‘The interval between one swelling and the next is the space described by the drop during one complete vibration, and is proportional, as Plateau has shown, to the square root of the head. The disturbances by which equilibrium is upset are impressed upon the fluid as it leaves the aperture. What really happens is, according to Prof. Magnus, that the rim of the orifice vibrates up and down, and the issuing stream receives alternate retardations and accelerations which lower down effect its resolution into drops. The continuous portion of the jet represents the distance travelled by any one of its elements before disintegration takes place; and its length depends upon the amplitude and wave-length of the disturbance. Now, if we have a jet of water which isinfluenced by a tuning- fork in the manner described, and another tuning-fork of slightly different pitch be sounded, and placed beside the first, producing beats with it, the continuous part of the stream will lengthen and contract in a remarkable manner, keeping time with the audible beats. This seems to be due to the fact just mentioned, namely, that the point of disintegration of the jet is determined, ceteris paribus, by the amplitude of the vibration affecting it. When the vibra- tions of the two forks coincide in phase, the resultant vibration has a maximum amplitude equal to the sum of the amplitudes of the two components, and the jet breaks high up. When the phases are opposite, the resultant amplitude is a minimum, and so the clear portion is lengthened. ‘The stream is extraordinarily sensitive to these beats, and will indicate them when the forks have become inaudible. If the stream be allowed to flow on to a stretched mem- brane of parchment or thin rubber, placed below the point where drops are formed, the impact of the drops will, in general, be heard as a series of taps—a mere noise.! 1 See ‘‘ Sympathetic Vibration of Jets,’”’ by C. A. Bell, m.z., Phil. Trans. Royal Society, Part 2, 1886, p. 399. Brtas—On the Structure of Water-Jets. 207 Now, if we break up the jet in a regular manner by a fork, a drop will be thrown off with each complete vibration, and hence, instead of a confused noise, a musical note will be heard—the note that the fork is yielding. The sound can be made very loud and penetrating, its quality depending on the nature and tension of the diaphragm and the pressure of the water. Tf the latter be suitably adjusted, a note will be emitted by the membrane without any fork being used; for the impacts of the drops will set up vibrations in the membrane which communicate themselves to the jet, and effect its regular resolution; and the note, when once established, will be maintained. If the pressure be increased, several notes may be obtained in succession, the pitch rising’ with the pressure. An interesting example of the Doppler effect may here be noticed. If the membrane be rapidly moved nearer the orifice, the pitch of the note will be raised during the motion; and on lowering the membrane, the pitch will be lowered. There is an experiment that can be performed in connection with this singing membrane that is very striking, and of some theoretical interest. Suppose the fork Ut,, making 512 complete vibrations per second, be placed on the stand. The membrane will respond to that note. Let it now be removed, and Sol,, giving 384 vibrations, substituted. The membrane again re- sponds, this time to Sol;. Place the two together on the stand, and a deep, powerful note of Ut,, or 128 vibrations, will be heard. It is, in fact, the difference-tone, or grave harmonic of the two forks. There has been for some years a controversy amongst physicists as to whether these difference-tones had an objective existence or not, that is whether there do really exist in the air vibrations of that period. Some held that they were purely subjective, and produced within the ear, owing largely to a peculiarity of construction of that organ, while others held that they existed in the external air. It would take too long to enter into the details upon which the respective arguments were based ; but Helmholtz showed, from mathematical considerations, that when a mass of air is set in motion by two simple sources of sound, in certain cases vibrations will arise with a frequency equal to the difference of frequencies of the generating tones. If such vibrations exist objectively (he 208 Scientific Proceedings, Royal Dublin Society. argued), they should be detected by means of suitably-tuned resonators—and, in a few cases, they can be—but more often than not, they are largely subjective. I hope to perform some further experiments in connection with this subject shortly. So far we have been considering the effects of sound upon jets of moderate diameter. Let us now see what happens when the jet is narrower. If a jet of water about one millimetre in diameter is projected almost vertically, it breaks up, and scatters into fine spray soon after leaving the orifice. Whena rather high-pitched tuning-fork is sounded and placed on the supporting stand, the scattering is prevented; and the stream, which now presents a beautifully wavy appearance, remains entire, until almost its highest point is reached. If we photograph such a jet falling normally, we can see, as in the former cases, that it consists of small and large drops alternating, irregularly spaced, and of various shapes. ‘T'he appearance of the same jet when influenced by a tuning-fork is quite different. (Plate XXII., fig. 1.) The drops formed are all about the same size, very regular in their outline, and practically equidistant. Fine streams may often be seen shooting out at the sides, particularly if the note be impure. The effect of a tuning-fork of high pitch on a very fine jet, projected upwards at a moderate angle, is very curious. The stream frequently divides into two, three, or more streams, quite distinct from each other. These streams revolve round one another, making it difficult to secure a satisfactory photograph. Plate XXII., fig. 3, shows the phenomenon well. ‘There is a central stream of drops larger than those constituting the others ; but all are arranged in perfect order, the drops in each stream being equidistant from their fellows. Plate XXILI., fig. 2, shows the same jet uninfluenced by sound. From the foregoing experiments, therefore, we see that the general effect of musical sound upon liquid jets is to make them regular and uniform ; and this is rendered evident to the eye by - their symmetry of form, and to the ear by the notes they produce. Brias—On the Structure of Water-Jets. 209 A musical note differs from a noise in having its vibrations periodic, and the smoother the curve that represents the wave- motion, the fuller and purer is the note. So it is with these jets of water. The more troubled and ruffled they appear to the eye, the more confused and irregular are the streams of drops that com- pose them ; while their symmetry and elegance of outline are but outward indications of order and regularity of formation. [Expranation oF Prarss. 210 Scientific Proceedings, Royal Dublin Society. EXPLANATION OF PLATE XIX. PLATE XIX. Fic. 1. A jet of water falling vertically from a glass nozzle, with an orifice 2 mm. in diameter. 2. The same jet broken up by a blow on its support. Pree, Ite! DSi, INotSay WOlls 2X; Puate XIX. z ‘ me t v1 e oe coma Beias—On the Structure of Water-Jets. 211 EXPLANATION OF PLATE XX. 212 Scientific Proceedings, Royal Dublin Society. PLATE XX. Fia. 2, 3,4. A jet of water under the influence of a vibrating tuning-fork (884 vibrations per sec.), showing successive stages in the formation of drops, and their phases of vibration. The point of disintegration has been considerably raised by the action of the tuning-fork, as may be seen by comparison with fig. 1, which represents the jet before the application of the tuning-fork. Proc. R.D.S., N.S., Vol. X. Puatt XX. oh ie Pern i ue soap oe ae Brtas—On the Structure of Water-Jets. 213 EXPLANATION OF PLATE XXI. SCIENT. PROC. R.D.S., VOL. X., PART II. 214 Scientific Proceedings, Royal Dublin Society. PLATE XXI. Successive portions of the same jet when influenced by a vibrating tuning-fork. Fic. 1. Lower part of the clear column, showing the disturbance travelling down with increasing amplitude, until disintegration takes place. 2. Middle of the jet. Collisions occurring between large and small drops. 3. Lowest part of the jet. Proc. R.D.S., N.S., Vol. X. Prats XXI. fart Gt Brtas—On the Structure of Water-Jets. 215 EXPLANATION OF PLATE XXII. 216 Scientific Proceedings, Royal Dublin Society. _ PLATE XXII. Fig. 1. A jet of water about 1 mm. diam., falling vertically, influenced by a vibrating tuning-fork. 2. A jet of water about ‘75 mm. diam., projected upwards. 3. Resolution of the same upward jet into three distinct streams, by a tuning-fork making 512 vibrations per second. Pratt XXIT Proc. R.D.S., N.S., Vol. X. == 6 O@9G0 G20G206000 66 000 8 C8 ; ; Se thie ; Remedies | XXIII. REMARKS ON THE CASES OF CARBON MONOXIDE ASPHYXI- ATION THAT HAVE OCCURRED IN DUBLIN SINCE THE ADDITION OF CARBURETTED WATER-GAS TO THE ORDINARY COAL-GAS. By HE. J. McWHENEY, M.A., M.D., D.P.H., M.B.L.A., Professor of Pathology at the Catholic University Medical School; Pathologist to the Mater Misericordie Hospital, Dublin. [Read, Aprin 19; Received for Publication, May 20; Published, Ocroprr 27, 1904.} In a paper read before the Royal Dublin Society in 1900, and entitled ‘‘Recent Analyses of the Dublin Gas-supply and Observations thereon,’’’ Professor James Hmerson Reynolds, F.R.S., drew attention to the increased proportion of carbon monoxide in the Dublin illuminating-gas. The mean result of twelve analyses made between November 25th, 1899, and February 16th, 1900, was a CO percentage of 6-2, which may be taken as the amount normally present. An analysis of ordinary coal-gas, published in Sutton’s “ Volumetric Analysis,” gives the CO as 5°68 per cent. ; and a sample of house coal (probably Orrell), which Mr. Holms Pollok, of the Royal College of Science, was good enough to test for me, yielded a gas containing 6°6 per cent. of carbon monoxide. Towards the end of February, 1900, Professor Reynolds noted a sudden and marked increase in the proportion of CO present, which on March 9th amounted to no less than 17-9 per cent., or nearly threefold what it had previously averaged. Furthermore, this increase in the carbon monoxide was, with certain fluctuations, persistent ; and, so far as I am aware, it has lasted uninterruptedly up to the present time. The mean of five analyses made in January, 1901, by Mr. Holms Pollok, was 10-3 per cent. of CO. Of late the tendency seems to be towards an increase; for the average of three analyses, very 1Scientific Proceedings, R.D.S., vol. ix. (N.S.), Part III., No. 21. SCIEN. PROC. R.D.S., VOL. X., PART II. Ss 218 Scientific Proceedings, Royal Dublin Society. kindly carried out by the same authority at my request this week, was 16°2 per cent. of carbon monoxide. From the health point of view, carbon monoxide is the most objectionable of all con- stituents of coal-gas. Its presence in increased quantity is to be ascribed to the addition of what is known as “ carburetted water-gas”’ to the coal-gas during the process of manufacture. Carburetted water-gas is made by passing steam over red-hot coke, whereupon the carbon of the coke combines with the oxygen of the water-vapour, and forms carbon monoxide, whilst hydrogen is liberated, according to the equation HJ0+C=CO+H,. The mixture of carbon monoxide and hydrogen burns with an almost non-luminous flame, and is nearly inodorous. A. subsequent addition of vapourised petroleum or other oils confers upon it illuminating power, and a powerful odour, which is, to most people, very objectionable,‘ but which has the important advantage of betraying its presence. Manufactured as it is to a large extent from the by-products of the ordinary industry, carburetted water- gas is cheap; and its additicn in considerable volume to the ordinary gas is therefore profitable to the producing company. It contains about 30 per cent. of carbon monoxide, and its introduction into dwellings is therefore by no means a matter of indifference to the public. Carbon monoxide is an extremely dangerous substance, which owes its deleterious effect on the animal economy to the intense affinity which it has for the heemoglobin of the blood—an affinity which has been calculated to be almost exactly 300 times as great as that between hemo- globin and oxygen. For it has been found’ that if blood be shaken up with a sample of air containing 0°07 per cent. of CO— in other words, 10,000 volumes of which contain 2,100 volumes of oxygen and 7 of CO—one-half of the hemoglobin will be found saturated with O, and the other half with CO, which amounts to saying that air containing only one-three-hundredth of its volume of carbon monoxide will half saturate the blood with that gas. ‘The result is that at each inspiration of such air a certain pro- portion of the hemoglobin is deprived of its oxygen-carrying function, and after a longer or shorter time, according to the proportion of CO present, the amount of functional hemoglobin 1 See Lorrain Smith: British Medical Journal, April 1st, 1899. McWerenry— Cases of Carbon Monoxide Asphyxiation. 219 becomes insufficient for tissue metabolism, the cardiac and respi- ratory functions fail, and the patient dies asphyxiated. Experi- ments have shown that when the atmosphere of a room comes to contain two volumes of carbon monoxide per thousand of air, it becomes dangerous, and when the proportion reaches four per thousand, life is speedily extinguished. The Departmental Committee appointed some years ago by the Home office to inquire into the manufacture and use of water-gas and other gases containing large proportions of carbon monoxide, referred in their Report, published in 1899, to American statistics, as showing the danger of this substance. A table prepared by Dr. Haldane, F.R.S., in the Appendix to that Report, shows that with ordinary coal-gas the annual deaths in England by gas-poisoning, calculated on a gas-distribution equal to that of London in 1896, were three in number; whereas the deaths that occurred in Boston, U.S.A., during the same year, would have amounted to 620, calculated on the same gas-consump- tion, and in Brooklyn the number would have been 400. In Boston the gas supplied consists of 90 per cent. water-gas, whilst in Brooklyn the proportion is 97 per cent. Dr. Haldane goes on to say: “ From the table it is evident that by no possibility can the conclusion be avoided that the distribution of carburetted water- gas without any special precaution is enormously more dangerous, or, to speak more correctly, less safe, than the distribution of coal- gas. Roughly speaking, the loss of life arising in one way or another—accident, suicide, or homicide—appears to be fully a hundred times greater with water-gas in America than with coal- gas in this country.” It would appear that in 1886 there were in Boston 29,554 consumers of ordinary coal-gas without accident. In 1890, amongst 46,848 consumers of a gas-supply containing 8 per cent. of added water-gas, there were six deaths from gas-poisoning. In 1895 the consumers were 68,214, 90 per cent. of the gas was water-gas, and the deaths were twenty-four. In 1897, with 79,893 consumers, and a gas containing 93 per cent. of water-gas, the deaths were forty-five in number. Dr. Haldane, on whose researches the Report of the Committee is mainly based, further points out that the number of accidents referable to the use of mixed gas would appear to increase approximately as the cube of the gain in percentage of carbon monoxide. 'Thus, if the 82 220 Scientific Proceedings, Royal Dublin Society. percentage of CO be increased from six to twelve, the chance of being poisoned is not twice, or even four times, but eight times as great as before the increase; and if the CO becomes three times as abundant as heretofore, the chances of being poisoned become increased no less than twenty-sevenfold. I was recently asked the very pertinent question, what number of the Dublin fatalities would have been averted had the supply consisted of ordinary coal- gas. The nearest approach to a correct answer is to be expected from a survey of the statistics of deaths from this cause certified in Dublin during the twenty years previous to the commence- ment of the introduction of water-gas. To the kindness of the Registrar-General (R. EH. Matheson, Hsq., LL.D.), who was good enough to have the Dublin death tabulation sheets, for the years 1880-1900, examined, I owe the important information that during that period no death was tabulated as having resulted from coal-gas poisoning. During the four years that have elapsed since the addition of carburetted water-gas has begun to be practised, there have been in Dublin ten cases, with seven deaths due to that cause. It would therefore seem impossible to escape from the conclusion that coal-gas with this addition constitutes a new source of danger to the community—one which is readily avoidable, no doubt, but which ought not to be completely overlooked. The cases that have occurred since the publication of Dr. Reynolds’s paper afford a full justification for the words of warning which he thought it his duty to utter, and in the course of which, whilst deprecating “undue alarm” and “exaggerated fears,” he emphasized the need for “ increased caution in dealing with the new gas.” Group I. (comprising Cases 1, 2, 3 and 4). These occurred in November, 1901, in a small house, No. 9, Eceles-place, to which gas was not laid on. It contained only two rooms, one over the other. In the upper room slept an elderly man of the working class (J. C., aged seventy, coal-labourer), and 1Jn 1895 a death occurred which, according to the finding of the coroner’s jury, was caused by ‘‘coma from congestion of brain and lungs, due to inhalation (accidental) of poisonous gases at Gas Company’s premises.” McWerrnty—Cases of Oarbon Monowide Asphywiation. 221 his son (A. C., aged twenty-one). In thelower room slept the old man’s daughter and her husband. On the 15th November all four persons were feeling unwell, and the son-in-law sent for a doctor, who, on arrival, perceived a strong, unpleasant odour, suggestive of a mixture of coal- with sewer-gas, pervading the house. He cautioned the inmates on no account to sleep in the house that night. ‘To this warning they paid no heed, and slept there as usual, retiring at 10 p.m. Next morning, between 6 and 7, the son-in-law felt so unwell that he left his bed and went to the Mater Hospital, where the resident pupil treated him. He had vomited, and complained of headache and prostration. After a time he felt better, and returned home. Nothing more was heard of the family till noon on the following day (Nov. 17), when another married daughter of old C. knocked, and, after some delay, was admitted by the son-in-law (the man who had called in the doctor on the 15th, and had been to the hospital in the early morning of the 16th). After opening the door he staggered, and appeared to be giddy and stupefied. His wife’s condition was similar. ‘The police were sent for; and, on going upstairs, they found the old man lying dead. The body was unclothed, and lay beside the bed. The son was found sitting in a dazed condition at the top of the stairs. Condition of survivors.—The son (who slept in the same room as the deceased) was, on admission to Dr. Redmond’s ward in the Mater Misericordize Hospital, found to be pale, semi-collapsed, almost unable to walk; temp. normal; pulse 120. He complained of feeling cold, but not of headache. Unfortunately the blood was not examined till next day (Monday), when it no ionger showed any trace of carbon monoxide. A blood-count yielded reds 4,800,000, whites 10,000, about 60 per cent. of which were polynuclear, and the remainder lymphocytes, small and large. The son-in-law, who with his wife occupied the lower room, was found, on admission, to have a very slow pulse, about 48. He complained of severe headache. In these respects his condi- tion was the reverse of that of his brother-in-law. He was almost unable to walk. His reds were 6,000,000, his whites 8,700, with 30 per cent. of mononuclears. Carboxy-hemoglobin not demon- strable. 222 _ Scientific Proceedings, Royal Dublin Society. The young woman’s symptoms soon passed off, and she refused admission to hospital. The post-mortem examination of the body of the old man revealed the usual signs of poisoning by carbon monoxide, as well as other points, which it would be out of place: here to detail. The blood was mostly uncoagulated, bright cherry- red. Suitably diluted, it gave an absorption-spectrum hardly distinguishable from that of normal blood, but differing from the latter in the persistence of the bands after treatment with ammonium sulphide sol., and warming. The dilute solution had a characteristically pink colour; and, on being tested by Haldane’s quantitative method, it yielded a result corresponding’ to 73 per cent. saturation of eae hemoglobin with carbon monoxide. Inspection of the premises.—Gas not laid on, and no fittings.. Lower room, 19 ft. 4 in. by 16 ft. wide, and 9 ft. high; small window and fireplace. Upper room (where the fatal case occurred),. 18 ft. by 15 ft., with a sloping roof, rising from about 5 ft. to: 74 ft. above floor. The three windows, nearly on floor-level, measured 3 ft. 2 in. by 2 ft. 10 in. each. There was also a sky- light, 2 ft. 1 in. by 1 ft.5in. There was no fireplace. All the windows were found shut when the room was entered by the police. The skylight was open when I visited the place, and there was: some doubt as to whether it had not been found partly open at the time of the fatality. It was situated nearly over the head of the stair, and far away from the bed. Explanation of the occurrence.—The premises, on being entered, smelt strongly of coal-gas, as did also the next house, occupied by a man, his wife, and six children, who do not appear, however, to: have suffered any ill-effects. Examination by the officials of the Gas Company showed that the main-pipe in the street was broken about 18 inches below the surface. The fracture was recent, and was: ascribed to the weight of some passing vehicle. The surrounding” earth smelt strongly of gas, which must have found its way through the soil into the house where the fatality occurred. The sewers were examined, and found staunch. It is interesting to note that though the gas entered below, its effects were most severely felt in the upper room. This is accounted for by the existence of an additional means of ventilation in the shape of a fire in the lower apartment. McWeeEnry—Cases of Carbon Monowide Asphyxiation. 223 Group II. (Cases 5, 6, and 7.) These cases were those of a family, consisting of a man, aged thirty-eight (mechanical engineer), his wife, aged twenty-six, and their child, aged five years, who were found dead in their cottage on the evening of the 7th April, 1902. Having been absent on the Continent when this case occurred, I owe my knowledge of it to the courtesy of the City Coroner (L. A. Byrne, Esq., F.R.C.S.), who placed the depositions at my disposal. The family were about as usual on the previous day. Several persons having called at the house during the morning and early afternoon of the 7th, and, having failed to elicit any response from the inmates, the door was forced towards 8 p.m. by the police, who were at once driven back by an overpowering odour of coal-gas. After the lapse of fifteen minutes an entrance was effected, when the man was found lying dead on the floor of the front room, attired only in a shirt, as though he had risen from bed, and attempted to reach the door. The dead bodies of the woman and child were found in bed in the same room. Death had occurred some hours previously. Inspection of the premises.—The “ penny-in-the-slot”’ meter, which stood on a shelf in the living-room, had been disconnected and removed, and, by means of two pieces of brass-pipe and flexible rubber-tube, a direct connexion effected between the gas-main and the house-supply. The brass tubes used were of smaller bore than ' the gas-pipes, into which they were inserted, the joints being made staunch with red-lead. Over the free ends of the brass- pipes, so fixed, the length of rubber-tubing had been slipped, and the gas thus “short-circuited ” intothe house. Unfortunately for the inmates, the rubber-tube had in some way become detached during the night, with the result that all three were asphyxiated. » Necropsy.—This was carried out next day, in all three cases, by Dr. H. C. Earl, at the Coroner’s request. The notes describe the peculiar pink colour of the post-mortem staining, the bright cherry-red colour of the uncoagulated blood, and its characteristic behaviour to the usual chemical and spectroscopic tests. The cause of death in each case was poisoning with carbon monoxide gas. 224 Scientific Proceedings, Royal Dublin Society. Explanation of the Occurrence.—This man was a mechanical engineer; and it is only too evident that his life, and those of his wife and child, were sacrificed in a clumsy attempt to defraud the Gas Company. Group III. Cases 8 and 9 were those of a married couple, J. and G. M., who were asphyxiated in their bedroom at a Dublin hotel on January 15th, 1903. They had arrived on the previous evening, and engaged the room, to which they subsequently retired. Next day nothing was seen of them, though it would appear that sounds of stertorous breathing were heard in the narrow corridor into which the room opened. Towards evening the hotel people became alarmed, and directed the porter to effect an entrance, which he did, through the windew. Dr. Martin Dempsey was sent for. He pronounced the woman dead, and ordered that the man, who was lying unconscious beside her in bed, should be removed to hospital. He was taken to Jervis-street, and admitted into Dr. Thompson’s ward, but never recovered consciousness, and died on the third day. Next day, at the Coroner’s request, I performed the autopsy of the female; and from the notes taken at the time, which are of a purely technical character, I will merely give the fact that the blood was found between 60 and 70 per cent. saturated with carbon monoxide. The man, J. M., lived three days in Jervis-street Hospital. He continued to breathe ster- torously, and was absolutely unconscious, incapable of any volun- tary movement, and irresponsive to stimulation. He was treated by inhalations of oxygen. On the day after his admission the blood looked very dark and tarry: carbon monoxide could not be demonstrated in it. The red corpuscles were 7,640,000, and the white 10,000, per cubic millimetre. The differential leucocyte- count worked out approximately normal. The temperature rose from 101° on admission, to 103° on the following day. It was 106° on the morning of the third day, and towards evening it was over 108°, when he died. Necropsy.—This was fully and carefully done by myself, with the assistance of the house surgeons, Drs. Ryan and Mason, but elicited no special abnormality. The blood in the cavities of the heart was for the most part coagulated; it did not yield a pink McWeenty—Cases of Carbon Monoxide Asphyxiation. 225 solution, nor could any trace of carboxy-hemoglobin be detected in it by the spectroscope. In view of the evidence of the clinical symptoms, and of the results of the autopsy of the female, I concluded that death was due to poisoning with carbon monoxide, and the jury so found. Explanation of the occurrence.—When the room was entered at 6.30 p.m., it was in darkness, and smelt strongly of gas, which was found to be escaping from a wall-bracket, the stop-cock of which was about half open. How this had come about was not fully cleared up at the inquest. Possibly the luckless couple, who had dwelt in the country, far from a gas-supply, may have blown out the flame. There is another possibility which deserves explicit mention. The corridor into which this room opened is a dark one and lighted by gas. The supply to it and the rooms opening off it was governed by a special stop-cock, which would appear, from the evidence, to have been, at any rate occasionally, turned off at night, and turned on next morning. If this had occurred on the night in question, and the couple had retired to rest, leaving the gas in their room lighted, the state of things found would be most probably accounted for. Inspection of room.—I personally inspected the bedroom, and noted the following points. The dimensions were 11 ft. 1 in. by 10 ft. 6in., by 9 ft. Gin. high, giving a cubic space of 1,105 ft., from which the space occupied by a large wardrobe 6 ft. 7 in. high, 44 in. wide, and 19 in. deep had to be deducted; a large double bed, 6 ft. 5 in. long, 443 in. wide, and 14 in. thick. There were also a large dressing-table, a toilet-table, a large basket-chair, and two ordinary ones—in fact, the little room may be said to have been crowded up with furniture. The cubic space thus occupied I esti- mated at 71 cubic feet, thus leaving only 1,034 cubic feet available for respiration. There was no fireplace. On the side opposite the - door was a large window, which was closed, but not fastened. The only ventilation at the time of the occurrence was into a dark and close-smelling corridor, and was effected through two sets of aper- tures, one being a series of slits in a pane of muffed glass over the door. These were eighteen in number, and arranged in three horizontal rows of six. Hach slit was 12in. long, by about tin. wide, and their conjoint area I estimated at rather less than 6 square inches. There was also a perforated zinc plate, pierced 226 Scientific Proceedings, Royal Dublin Society. with holes, and let into the wall close to the floor under the head of the bed. The conjoint area of the holes might have been about 2() square inches on a liberal estimate. Their ventilating value must have been seriously diminished by their position close to the floor ; they opened into the corridor. Assuming the admitted air to be cooler than that already in the room, the effect would be to form on the floor a stratum of purer air, which could only slowly affect the composition of the general atmosphere of the room. The wall-bracket was furnished with a No. 5 brased fish-tail burner, consuming about 5 feet of gas per hour. The fatal result was in this case due to several circumstances, of which the leading one was undoubtedly the escape of gas ; whilst the defective ventilation of the apartment, in which the unfortunate couple were allowed to remain shut up without food or attendance throughout the entire day, was a contributory factor. On comparing the ventilation with the recognised standards, we find that the cubic space was 517 feet per head (instead of 1,000). The functional “fresh” air inlet was only 8 square inches; but allowing the same value for any advantage that might have accrued from the perforated zine plate beneath the bed, let us say 16 square inches (instead of 48). Of course, air can enter through any crevice. Dr. Haldane has shown that the air of such a room is changed, even in the absence of a fire-place, about once every 2; hours. It would, therefore, be quite a mistake to suppose that the ventilation of a room, with, at any rate, one of its walls an outer one (that is, forming part of the outside of the house), is solely dependent on the ventilation apertures made ad hoc. Pettenkofer experimented many years ago with a room of about 8,000 cubic feet capacity, and found that without definite ventilation, the air was changed once every 3 or 4 hours. Dr. Haldane, in his Appendix to the Gas Commission Report, concludes that the air of a closed room of 1,000 cubic feet capacity is changed once in from 2 to 3 hours. It may be interesting to inquire what was the condition of the air of this particular bedroom, assuming that the air was completely changed once every 2} hours by diffusion through the walls, and, for the sake of ease in calcula- tion, that its cubic content was 1,000 (instead of 1,034) cubic feet. We shall also assume that the gas continued burning for 2 hours McWernrey—Cases of Carbon Monowide Asphyxiation. 227 after the couple retired to the room (that is, till 12 o’clock), and then became extinguished. The problem may, therefore, be stated thus :— A room has a capacity of 1,000 cubic feet, and the atmosphere is changed once every 2°25 hours. Its original composition may be assumed normal (790 vols. of N, 209°6 of O, and 0-4 of COQ,). CO, is introduced (a) by combustion of coal-gas, (>) by respira- tion: (a) goes on for only 2 hours (at the rate of 5 feet per hour), and delivers 2°5 cubic feet of CO, per hour (being at the rate of half a foot of CO, per foot of gas burnt; () continues all through the experiment, which lasts from 10 p.m. till 6 p.m. next day (20 hours), and delivers 1:2 cubic feet CO, per hour (0°6 per individual). Coal-gas is delivered into the room during the last 18 hours of the experiment at the rate of 5 feet per hour. It contains 16 per cent. of carbon monoxide. Required—(1) The maximum percentage of CO, that will be reached in the atmosphere. (2) How long it will be before it will be reached. (3) The maximum percentage of CO which will be reached during the experimental period. (4) How long it will be before the maximum percentage is reached. It is assumed that the entering air is normal in composition, and that it at once and completely mingles with the air already in the room. I have submitted this problem to a competent mathematical authority, who reports as follows :—The CO, introduced attains its maximum at the end of the first 2 hours, when it is 4:9 cubic feet. It then decreases during the 18 hours to practically 2°7 cubic feet. The change is more rapid at the beginning and very gradual towards the end. It is 3°51 cubic feet at the end of 2°25 hours, and 3 cubic feet at the end of 4:5 hours, so from this it changes very little. As regards the coal-gas, the percentage goes on increasing all the time, tending towards the theoretical maximum which would be 11:25 cubic feet, containing 1:8 cubic feet of CO. That 11-25 cubic feet is the maximum is shown by the fact that the wastage Scientific Proceedings, Royal Dublin Society. 228 4X0} OY} UL pouoryuouL suorjduinsse oy} uo pus ‘Aouvdnooo Jo ported Surmmp OD pue 2Q{ Jo Joos o1qno ur WoOI Jo 4U9zUOD Fo UoryeyUEserdor oTydery 0-0 Pees ee dS ealeg) aus) Se eae HH: See 5 SRG SS ERSENS oaae w°7 Tee ee £0: 1°91 £0. 1- OQNIdVDS3 SV ONINUNG SVD McWeeney— Cases of Carbon Monoxide Asphyxiation. 229 11:25 227 what is delivered per hour. The maximum is never actually reached ; but at the end of 18 hours the quantity of coal-gas present is 11:246, containing 1,799 of CO, which is for all practical purposes the same. The curves show the percentage of CO and CO, present at the stated intervals, on the assumptions already stated. Inasmuch, however, as the tap was not fully open, and there- fore delivered less than 5 feet of gas per hour, they represent an over-estimate of the amount of carbon mon- and di-oxide con- tained in the room. ‘Their value lies in a fact which they bring out, viz., that asphyxiation may be induced in a room where the proportion of carbon monoxide, i the atmosphere as a whole, falls short of 2 per cent. The fatal result was, no doubt, due to the carbon monoxide having been unequally distributed through the room, so that the two persons may, at times, have been breathing an atmosphere much more highly charged with the poisonous gas. per hour would be = =~ or 5 cubic feet, which is balanced by Group IV. (Case 10.) The last case is of interest as illustrating the danger of badly- constructed arrangements for the rapid heating of bath-water— what are known as “ Geysers.” On the night of March 30, 1904, at about 9 o’clock, J. J. K., aged 29, pharmaceutical chemist, went to take a bath at his residence. About three-quarters of an hour afterwards, the female servant, who had been out on an errand, returned, and, ou passing the bath-room on her way upstairs, noticed nothing particular. Shortly afterwards, on her way down, she remarked a powerful odour of gas in the lobby. She saw the light in the bath-room shining through the muffed-glass door, knocked, could hear no sound, and becoming alarmed, sent for the caretaker, who burst open the door, when the body of the unfortunate young man was found lying just inside, in the narrow space intervening between the bath and the door. He was completely undressed, and the hair was wet. He had evidently been in the bath. So over- powering was the odour of gas that the caretaker was partially 230 Scientific Proceedings, Royal Dublin Society. overcome, and with much difficulty dragged the body out into the lobby, where he applied artificial respiration, sending mean- while for medical assistance. Dr. Herbert Byrne, the medical officer of the district, speedily arrived, and could only pronounce life extinct. The necropsy, done by myself next day at the Coroner’s request, revealed no trace of any disease in the body, which was that of a finely-developed young man. Rigor mortis extreme: the blood was still perfectly fluid, and bright cherry-red in hue. I may add that it was still uncoagulated a fortnight after collection. I was unable to detect much difference between a dilute solution of this blood and a similar one of normal blood (my own) after shaking with coal-gas to complete saturation. An accurate titra- tion by Haldane’s colorimetric method revealed the fact that the sample which I took from the right auricle was 87:3 per cent., and the sample from the left auricle 87-7 per cent., saturated with carbon monoxide. I learn from Prof. Lorrain Smith, of Belfast, who kindly did the titration for me, that this is the highest percentage of satura- tion as yet seen in the human subject. There remained only one- eighth of the subject’s hemoglobin available for oxygen-carriage. The deceased would appear to have sat reclining in the bath until deprived of seven-eighths of his heemoglobin, and on arising and attempting to step out, had fallen unconscious on the floor, where death must have speedily supervened. Inspection of the premises.—A bath-room about 7 feet by 7, with a sloping roof varying from 6 to 73 feet high. Most of the available floor-space was taken up by a full-sized metal bath and a pedestal w. e. which stood beside it, at the head end. At the other end was a chair, and there was just space to stand com- fortably between the door and the side of the bath. ‘The upper half of the wide double doors was glazed with muffed glass. They fitted tightly. On the other side of the bath wasa large “ French”’ window, which was closed at the time of the occurrence. On the same side of the room was an ordinary ‘‘ Sheringham ” valve, near the roof. Its flap was properly counterbalanced by a weight, and was described at the inquest as “ slightly open” at the time of the occurrence. The “ Geyser” was placed over the foot end of the bath. It consisted of a metal heater of about two gallons McWerntey— Cases of Carbon Monoxide Asphyxiation. (231 capacity, into which water was led through a pipe connected with the supply to the bath. From this receptacle a brass pipe opened over the bath. Underneath, in a space partly surrounded by a japanned metal jacket, but open in front, stood what might be described as a “battery” of six powerful Bunsen burners, which were supplied by a half-inch-bore gas-pipe, from which an ordinary wall-bracket was also taken off. The heated air and products of combustion were carried up round the sides of the boiler within an outer metal casing, which was contracted over the top of the boiler into a sort of funnel discharging them into the room. There was no ventilation pipe. The ceiling was guarded by a metal disc from being blackened by the products of combustion discharged from the funnel. There was no safeguard whatever for the life of the luckless person who might shut himself up in this nearly air-tight space of 350 cubic feet, with six Bunsens capable of burning about 60 feet of gas, and, therefore, of consuming some 300 feet of air in asingle hour! The poisonous condition of the air may be accounted for in various ways :— 1. One or more of the burners may have remained unlighted. ' All were on the same tap. 2. They may have “struck back.” 3. The flames, by impinging on a cold metallic surface, may have had their temperature so much lowered that com- bustion became imperfect, and CO was consequently liberated. 4. The air in the bath-room may have become charged to such an extent with the products of combustion that the gas was only partly consumed, with consequent libera- tion of carbon monoxide. Whatever may have been the immediate cause, the fact remains that had the Geyser been ventilated into the outer air, this young man’s life would have been saved. Several similar mishaps have been recorded from the use of badly-ventilated apparatus for the heating of water. ‘Iwo are referred to in the Appendix to the Report of the Water-gas Committee; and I have since come 232 Scientific Proceedings, Royal Dublin Society. across a third, reported in the Deutsche Medicinische Wochenschrift for February 4th, 1904, by Dr. Scheven, throat-surgeon of Frank- furt-am-Main. The patient was taken unconscious from his bath, and, after some hours of active treatment (which comprised hypo- dermics of camphor, intra-venous injection of 1,500 cem. of warm saline solution, artificial respiration, and inhalations of oxygen), he recovered. The bath was heated by a Geyser, which, on examina- tion by an expert, was pronounced to be in good working order, but which was not ventilated. The bath-room was relatively large, 10 feet high, and with a capacity of 660 cubic feet. Dr. Scheven’s theory is, that so large a consumption of gas as is needed for the rapid heating of the bath-water must necessarily diminish the oxygen content of a small enclosed space to such an extent as to lead to imperfect combustion and formation of carbon monoxide. In order to test this, he fixed a number of candles at varying heights in the bath-room, and set the Geyser going. In ten minutes all the candles were extinguished. His second experiment consisted in hanging up a cage, containing a large white rat, 19 inches from the roof. A second cage, containing two smaller rats, was put on the floor. The Geyser was then set going; and on entering the room in twenty minutes—the time necessary to prepare a full bath—the rat in the upper cage was already dead, whilst the two animals in the cage on the floor were lying on their side quite unconscious, but still breathing. They recovered in three-quarters of an hour. The large rat in the upper cage was examined, and found to present the typical signs of carbon monoxide poisoning. I am unable to say whether the gas supply of Frankfurt contains an admixture of carburetted water- gas; but, in any case, the fact remains that unventilated Geysers are distinctly dangerous, and should not be allowed.* 1 On this day (19th May, 1904), in the act of preparing the MS. of this paper for the press, I see in the English daily papers the account of a similar accident from the use of a Geyser at Birmingham. A nurse-maid was engaged in bathing two children, when all three became unconscious, and the younger child slipped into the bath and was drowned. The medical evidence showed the presence of carbon monoxide in the blood, and attributed the sudden unconsciousness of the other two persons to the same cause. The Geyser was unventilated. McWsEnEY— Cases of Carbon Monoxide Asphyxiation. 233 ConcLupDING REMARKS. Carburetted water-gas is convenient, cheap, and can be more readily and quickly produced in large quantities, to meet sudden emergencies, such as might be caused by fog or by the breakdown of an electric system of lighting, than coal-gas. For these reasons I believe that 7¢ has come to stay; and I should be the last person to reproach a Gas Company for availing itself of so impor- tant an improvement in their procedure. My reason for writing this paper is to warn the public that in dealing with this gas greater precaution is required than in dealing with ordinary coal- gas. ‘The experience of the great American cities shows that where the illuminating-gas consists nearly altogether of water-gas. accidents have increased between fifty- and one hundred-fold from its use. ‘The delivery into houses of so poisonous a gas likewise affords undesirable possibilities for suicide, and even for homicide— facilities which, it would seem, are being increasingly availed of in the United States. In view of the fact that whilst little or no danger results from the leakage of ordinary gas, considerable danger does result from leakage of gas containing a considerable proportion of water-gas, the rational and proper course of procedure would, I think, be for — the sanitary authorities to take action in the matter. The action which I suggest they should take comprises the following steps :— 1. To require of companies or persons selling gas to make notification beforehand of their intention to increase the pro- portion of the poisonous constituent (carbon monoxide) in such gas. 2. To require of such companies or persons that the said poisonous constituent shall not at any time exceed a certain proportion, say 15 or at the utmost 20 per cent. of the total volume of the gas supplied. ; 3. To require that when gas containing the full admissible proportion of the said constituent is being supplied, this shall only be during the day: the proportion supplied at night (when people are asleep, and the danger therefore greater) not to exceed 10 per cent. 4. To require of gas-producing companies that a daily state- ment be made of the proportion of carburetted water-gas supplied. SCIEN. PROC. R.D.S., VOL. X., PART II, 204 Scientific Proceedings, Royal Dublin Society. 5. To introduce in their gas-testing stations apparatus for testing the coal-gas as regards its content in carbon monoxide, and employ expert chemists to apply the test at stated intervals. 6. To require of gas-producers an account of the percentage of gas unaccounted for, the consumption of which cannot be traced. This would afford some measure of the leakage through broken or defective mains. (See the first group of cases in this paper. ) 7. To direct constables on duty to take special note of any odour of gas arising from excavations in the streets, and report thereon. 8. To institute an inspection of gas-fittings, especially with regard (a) to taps unprovided with a stop, and therefore capable of being turned right round, so as to turn on the gas again in the act of cutting it off, and (6) to stoves and Geysers not provided with proper ventilating pipes or flues carried out to the open air. So far as I am aware, the existing law does not enable sanitary authorities to take such steps, and special legislation would therefore be required, except in regard to recommendation No. 8, which refers to defective fittings, as stoves, Geysers, gas-cookers, &c. These might be brought under the provisions of the Public Health Act (Ireland), 1878, section 107, and dealt with as nuisances. In conclusion, I may say that I do not desire in any way to excite public alarm on this subject, or to interfere with the legitimate prosecution and development of the gas-making industry. Having had the dangers of inhaling the gas, as recently manufactured, so forcibly brought under my notice, I have thought it well to bring the results of my observations under the notice of members of the Royal Dublin Society. I am convinced that should the question come to be looked upon as one of public inquiry, legislation will not fail to follow. I wish finally to express my sense of very special indebtedness to Professor Lorrain Smith, M.D., of Belfast, who kindly checked my results in determining the percentage saturation with carbon monoxide of the several samples of blood. I have also to thank the City Coroner and the Registrar-General for information courteously placed at my disposal. XXIV. PHOTOGRAPHS OF SPARK-SPECTRA FROM THE LARGE ROWLAND SPECTROMETER IN THE ROYAL UNIVER- SITY OF IRELAND. PART III: THE ULTRA-VIOLET SPARK-SPECTRA OF PLATINUM AND CHROMIUM. By W. E. ADENEY, D.Sc., A.R.C.8Sc.1., Curator and Examiner in Chemistry in the Royal University of Ireland. [Read, Marcu 19; Received for Publication, Marcu 22 ; Published, Supr. 17, 1904.] Tue wave-lengths of the lines in the ultra-violet spark-spectra of the metals platinum and chromium, which form the subject of this communication, have been calculated from measurements made from photographs of the first order of spectra, reproductions of which have been published in Part I. of this work. The measurements have been made by means of a light microscope, mounted on a stage which can be moved through a space of about one inch long by a short micrometer screw. Each line has been measured at least twice, and many of them three and four times. Kayser’'s measurements’ of well-defined lines in the arc- spectrum of platinum have been employed for standards. The conditions under which the photographs were obtained are described in Part I., and it is only necessary to state that the spectrum of platinum was derived from a pure specimen kindly presented to the author by Messrs. Matthey and Johnson. The chromium spectrum was obtained by sparking a saturated solution of pure potassium chromate between platinum electrodes. In the cases where the calculated wave-lengths of the interme- diate platinum lines have shown a close agreement with those by 1 For Part I. see Trans. Roy. Dublin Soc., Vol. vir. (Ser. 11.), 1901, p. 331, and for Part II., see Sci. Proc. Roy. Dublin Soc., Vol. x. (N.S.), Part I., No. 3, 1903. * Kayser, Konig]. Preuss. Akad. d. Wissench. Berlin, 1897. SCIEN. PROC., R.D.S., VOL. X., PART II. U 236 Scientific Proceedings, Royal Dublin Society. Kayser, the latter observer’s numbers have been adopted. In those cases in which they have not agreed, they have been confirmed, or corrected, by re-measuring the lines with a micro- scope and eye-piece micrometer, by Zeiss, the photographie plate being mounted on a carriage actuated by a micrometer screw. The lines were measured in reference to a standard scale formed by the lines of a photograph of a réseau belonging to the Observatory of Cambridge University. In the author’s photographs of the platinum and chromium spectra 443 lines have been measured between the two extreme limits of wave-length 2229°45 and 4560-21 in the former, and 1283 in the latter. Kayser gives between the same limits the wave-lengths of 497 lines. Exner and Haschek' have given in their list of the chromium lines, between the above limits of wave- length, measurements of 2027 lines. The author again has to acknowledge his indebtedness to Miss M. Hall for the very valuable assistance she has given in the work of making the micrometer measurements, and of calcu- lating from them the wave-lengths recorded in this communica- tion. 1! Kais. Akad. d. Wissensch., Wien, Sitzungsb. Math.-Naturw. Cl., Vol. cvz., 1897, p. 1133. AprenEY—Photographs of Spark-Spectra. 237 PLATINUM. KAYSER. ADENEY. ADENEY. 2229-45 2381°95 35°46 2383°73 83°73 45°65 84°47 50°76 86°52 51°63 86°89 53°38 87°45 87-44 56-20 89-62 89-61 62°73 90-14 63°37 90°92 64-08 91°86 66°63 96°24 96°24 67°55 96-76 96°77 74°53 2401-09 81°53 01-96 2401-96 87-63 03°18 03°18 88°38 05°84 92°55 10-39 96:03 13°14 2305°72 17°82 08-12 2308-12 18°14 10:97 18-15 13°04 20°91 20°91 15°58 15°58 24-96 24°96 18°37 18°37 26°52 19-96 28°21 28°21 26°19 26°30 29°19 28°60 29°42 31°05 34°55 34°55 39°58 36°77 36°77 40°26 40°26 39°53 42°87 40°16 40°16 43°47 43-36 42°72 46-82 45-60 47°24 50°53 50°53 48°62 51°05 53°12 55-22 56°42 60°16 57°18 57°18 61°47 57°66 67°50 67:50 63°93 69°54 65°37 71-09 71°06 66°55 73°25 68°36 68°36 15°94 71°68 77-37 17-28 81:27 78°04 82°05 78°77 83°31 83°33 80°04 83°45 81°45 87-26 87-26 U2 238 Scientific Proceedings, Royal Dublin Society. KAYSER. ADENEY. | KAYSER. ADENEY. 2488°82 2608°33 2489-01 2612-94 90°22 90°23 13°20 92°64 13°34 93°30 14-70 95°91 95°91 16°84 16°84 97-20 19-67 19-67 97-98 19:98 98-59 98°59 2500-90 21-12 03-08 21°63 04°13 25°42 25-42 2505°95 27°48 06°01 28°12 28-11 08-59 08°53 35°03 10°60 35°37 14:00 14:00 39°43 39°43 14°17 45°45 15°12 15°12 46-97 46°97 15-67 15-66. 50:94 50°91 17-27 63°87 20°36 56°91 22°62 — 58°27 58°28 23°1k 58°79 58-79 24°42 59°54 59°54 26°10 64°72 29°50 29°50 68°75 36°07 73°71 26°58 36°60 74-65 74°65 38°36 76°95 39°29 39°29 17°23 17°23 41°43 79°22 44-04 86°99 44°81 88°35 88°35 46-56 89°52 46-99 92°32 48°19 94°31 49°55: 96:07 51°36 98-50 98°50 52°33 2701-21 60°44 02:48 270248 64°26 05-99 05-99 68°62 : 11°03 72°72 72°72 13°22 13°20 14:58 14°61 78°51 15°87 81°30 17-71 igs 7il 82°42 19°13 19°13 83°38 21°97 87°89 25°43 96-08 96-08 26°52 99°15 30°00 30-00 99-99 i 30°86 2602-18 _ 83°73 03°22 2603-22 34°06 ~ 34:06 06°13 34°58 4°57 Apenry— Photographs of Spark- Spectra. ADENEY. | | KAYSER. 239 KAYSER. ADENEY. 2735-81 2814-12 9814-12 2736°89 17-21 37-66 18°35 38°57 38-54 18-74 43-54 18°95 44-93 21°18 47°70 47-70 22°27 49°32 22-60 22°58 53°85 23-34 53-96 53°96 24°44 54°33 25°19 55-00 55:00 30-40 30-42 57°58 31-64 57°80 31-98 58°16 33-60 58°33 34°82 34°78 59°42 37°34 63-30 63°38 37°64 66°76 39°35 69°10 42-08 69-94 69°94 44°35 71°75 71-72 45°32 72-93 47°97 73°35 48-41 73°70 49°24 74-10 74:10 53:21 53-20 74°31 53-48 74:88, 74-88 54°78 76°11 55°87 76°86 58-46 77-56 60°73 82°30 65-07 82:80 66-12 88-73 | 88°71 66°92 90°59 68°79 90:99 . 70°31 93-37 93°37 70-57 93-74 75-11 93°84 | 75°80 94°30 94-30 | 77°46 95°62 | 78-82 96:17 84-58 97-88 85-45 : 98-29 85°56 | 2800-10 $8-31 88°31 2800-56 90°50 90-51 | 02°77 91:03 03°34 03°34 91°17 06°15 91°87 07-40 | | 93°34 93°34 08-60 93:98 93-98 Mi 08-93 | 96-25 09-72 97-99 97-97 : 10-92 99°76 99°78 13:08 2900-90 ne 13-46 01-28 240 Scientific Proceedings, Royal Dublin Society. KAYSER. | ADENEY. ! KAYSER. ADENEY. 2901-°80 - ; 2987-00 03°13 2988-18 04°26 88-91 06:00 2906-03 89-92 89-92 08-01 08:05 94°92 | 08°93 98-09 98-09 10°57 99-18 11°89 3001-30 3001-30 12°30 02°39 02°39 12°88 03°40 13°36 + 04:27 13-66 13°64 05-91 14:22 07:87 14°44 10:05 15°28 12°50 16°51 12°70 19°45 19°45 14-64 21°34 15-01 21°50 21-50 15°32 22-38 17:40 23°45 17-45 25-32 18-00 18-00 27-04 19°12 27°81 19-96 28-23 28-23 22-96 22°96 29-90 29-90 24°41 24°41 30-90 30:90 25-18 31:70 25-34 33°84 . 20°67 38°94 38°94 26°45 26°45 41:22 31°36 41:91 36°55 36°55 42°88 42°88 39°61 oe 44°88 44-88 41:25 46°38 41°32 48°84 42°75 42°75 49-90 ave 47°31 50°93 48°60 51:34 54°40 55°93 54°80 58°65 58°65 55°40 55-40 59-22 59°22 56°13 59°83 56°72 60°86 60-84 59°75 59°75 62°10 61°91 | 67°60 62°30 69:97 ine 62:85 a: 73°84 64°83 64°83 74:25 69:21 i oat 78°18 70°37 cn 79°26 72°04 72°04 79°86 74°25 82°41 74°94 Z 83-88 83°88 75°12 pelts. : 84°57 ' 76°12 i 85°46 Bae. 76-80 : KAYSER. AvrnEY—Photographs of Spark-Spectra. ADENEY. KAYSER. 241 ADENEY. 3078-95 79°67 81:17 82-78 84-22 84-98 87-32 88-68 89-78 98°89 8100°15 01-08 02°71 03°23 03°70 04°17 12°72 18-55 19:91 22°19 23-07 32°19 33°44 33°79 34°41 36-38 39°50 41:77 54°86 56°69 59°84 60°31 69-01 74-96 76-08 raidaale 19-66 91°60 92°64 3079°67 81-17 82°55 84°20 97-16 3100-10 01-08 ~ 03°80 04-70 09°40 16°85 18°14 27°04 35°45 39°50 41-77 44°13 45-09 56:69 59°20 67°55 74:85 79-1] 79°52 88°24 91-23 92°64 3199-08 99-22 3200°85 04°17 | 07-35 08°97 12°50 18°60 18:97 20°90 21°42 22°68 22°93 27°31 30°40 33°55 40°32 41°65 43°22 43°53 47-39 48-62 48°84 50°48 52°12 52°79 53°32 55°36 56-05 56-63 58°55 59°28 59-87 61-20 61°82 63°74 68°56 82-10 83°34 83°44 85°37 87-25 3194°44 98-09 3200°89 04°20 12°60 24-16 27-35 30°42 33°53 39°43 40°31 43°82 47°67 50°48 62°12 56°05 59°86 61°13 61°84 65°40 67°25 68°56 73°29 74:17 82°10 83°44 84-99 85°97 88°20 242 Scientific Proceedings, Royal Dublin Society. KAYSER. ADENEY. KAYSER. ADENEY. 3290-36 3290-36 3491-16 3491°15 93°62 92-20 93-82 98-32 98-69 3501:70 3300-07 03-83 3300-29 3505°85 05:85 02-02 02-00 14:87 14°87 11-50 21-57 11-96 23-80 12°61 12°65 26-92 13-19 28-70 28-70 15°19 1518 32-90 23-91 23°94 34:48 25°68 36°14 25°86 48-69 27°23 51°67 29-60 60-60 32°24 61-97 38°21 65°10 38°34 72°18 40°22 77°43 42°43 87-55 44°03 44-03 3605°12 54-22 08-02 55°77 3611-06 11-06 on 57°05 15°44 67°14 67°14 21-84 21:84 68°63 25°30 71-00 28-28 28-28 72°96 29-03 29-03 74-09 37°32 77°38 38°96 38-96 83-91 43°33 43-32 3406-73 52-41 52°41 08-29 3408-29 54°13 54-19 14°61 ai" 54-89 17°23 17°23 59-57 59°87 18°31 63°24 63:24 20°49 64°32 26°89 26°89 68-20 28-08 28-08 68-56 31°50 72°17 72°15 32-00 82-00 74-21 74:19 47°92 75-11 75°09 48°52 75-96 53°98 81-23 81-25 64-29 83°17 83:16 55-96 87°58 87°58 57-22 3700-07 3700-05 64°10 06-69 06-66 72°08 ah 30°42 76°80 66°55 i 77°70 68°56 83°59 83-59 3801-20 85°43 "85°43 ‘08°18 ‘88-88 ‘12°58 Aprnry—Photographs of Spark-Spectra. 243 KAYSER. ADENEY. 3313°48 15°22 16°04 3818°83 18°83 68°59 75°87 98-88 98-90 3200°87 3900°87 03°86 04°53 04°53 06°22 06°43 11°06 11:04 25°11 23:12 25°48 25°48 33°83 Ca 48°55 48°55 53°78 66°51 66°51 on: 68°59 70:28 76°46 80°75 96°72 4002-65 4046:°55 54°98 61-68 65:95 66:09 81°63 81°63 92°43 4118-85 4118-85 48°50 64°71 64°71 92°58 92°55 4201°37 4226-85 KAYSER. 4247-84 51:28 63°66 69°41 74:04 81:91 88:22 91-07 4327°24 34°83 43°85 58°52 64:62 92-00 4411°58 14:42 37°47 42°73 45-71 73°63 81°81 84°88 93°35 98°93 4511-42 21°10 23°19 48-06 62°12 52°59 54°76 60°21 ADENEY. 4263-66 88°22 88°45 4302°60 27°24 34°83 37°00 58°52 64°62 72°10 92-00 4442-73 84°88 98:93 4514°33 21-10 23°19 48-06 52°59 54°76 60°21 244 Scientific Proceedings, Royal Dublin Society. CHROMIUM. - 2226-89 2466-62 2548-70 2608-90 36-00 68°07 49-60 10-20 43.75 69-22 51-70 11:04 44-93 72°87 55°59 11°70 48-65 75°05 57°16 12°19 58°01 75°76 58*45 12°65 73-50 77°01 59-93 13°17 75°66 17-71 60°80 13°62 76°55 78°81 61°08 14-80 77°68 80-80 61-80 16°42 89-40 83°11 62°03 18-75 90-78 83°85 62°56 19-79 97°34 86°39 63-49 20°60 2300-68 86°73 63°71 23°42 07-30 89°32 64*91 26°88 14-78 90°85 66°63 28°13 19-07 91°57 67°68 29-66 19-50 92°70 68-69 31-03 19-90 §2:95 69-60 32°67 20-09 96°45 70°86 33°63 24-97 96°95 71:91 34-38 26°50 98-06 72°28 35°93 33°55 98°82 73°66 36°55 34-41 2501°55 75*90 37°28 44-60 02°61 77°85 37°58 45°43 04°38 78°45 41-50 65°35 09°15 79°28 43°00 66-96 10°35 82°33 43°62 81°50 11:28 82°79 48°31 89°78 13°72 83°78 52°24 94-01 16-71 84°26 53°64 97°76 18°35 85°13 56-00 99°73 19-00 85°79 57°34 2400-35 19-65 87-56- 57°78 08-81 20°75 88°36 58-70 16°45 22°39 89-20 59-01 20°13 23°58 89-83 60°83 33-23 25°52 90-90 61-44 38°50 27-20 92-00 61°81 47°07 30°05 94°42 63°14 47-70 30°30 95°70 63°46 49-70 31°18 97°22 63-66 52°90 31-92 2601-92 65°68 54-11 34-42 03°15 66°15 54°51 38-49 03°81 68-00 55°30 43-25 04-26 68°77 56°75 44-45 05°72 70-18 60°56 46-12 06-22 71°88 63°56 46-55 06-61 72°43 64°52 47-57 07-11 72°91 65-69 48:16 08-01 14:17 el ApENEY— Photographs of Spark-Spectra. 245° 2674°75 2743°67 2787-92 2861-05 76°38 44-62 89-43 62°68 i 75°76 44-98 92°20 65°24 77°20 45-28 93°75 65:98 78°88 46-22 98-75 ' 66°83 80-00 47°84 2800-22 67-20 80°46 49°04 00-81 67°73 81-03 1 49°84 04-09 70°54. 81-98 50°77 08:07 71:58 83°58 51:92 10°19 73°57 84-41 52°88 10-93 73°90 84°88 . 53°73 11-56 74:63 86°17 53-93 12°07 76°06. 86°25 54°33 16°88 76°37 88-50 55°55 17°95 78°13 89°35 55°84 18°39 78°53 89-98 56°33 20°52 79°34 90°42 56-98 21:93 81:00 91°20 57°77 22-40 82°05 92-28 59°01 25-37 85°39 94°83 59°41 26-09 86°50 96°87 59-80 28°01 87:13 97°64 60°17 28-76 87:88 98-02 60°57 29-68 88°85 98°53 61:77 30°46 89°31 98-86 62°76 32°53 89-60 270020 63°66 33°51 89-95 01°77 64-08 34°39 91-28 02°08 64°38 35°75 91-38 03°65 65°05 36°65 91-98 03-90 65°46 38-06 93°04 04-90 65°72 38:92 93°34 05°62 65:97 38°67 | 94:38 06°02 66:63 40°13 94:95 08°88 : 67°70 43°09 95:02 09°40 68-28 43°19 95°82 11:04 68°60 43-39 96°52 12°40 69°52 46°52 96:85 17, 69°93 46°82 97-33 17:60 71-40 48-52 97:83 18°45 72°08 49°40 | 98°64 20°18 72°36 49-93 99-26 20°74 73°40 50-76 99°61, 22°80 74:51 51-41 2900°58 23°68 76°71 52°39 t 01:10 24-32 eon 52-80 02°73 26°58 78°15 53°30 02:92 27°33 78:98 53°83 03°79 28°24 80°35 64°25 04°08 31-98 81-04 54°74 04-78 34°62 : 82°43 55°17 i 05-60 35°80 82°64 55°79 06°32 36°50 83:95 56°48 | 07°15 37°14 84°55 56°89 : 08-40 37-70 85°31 57°50 ( 09°12 40-12 85°75 58-09 } 10°73 41:13 86°55 58-76 H 11°13 42°12 87°67 59-01 4 11-27 246 Scientific Proceedings, Royal Dublin Society. 2911-79 2975-55 3043°97 3117-34 15°34 76°78 44°29 18°18 15°56 79°88 45°71 18°74 16°12 80:87 47°09 19°29 17°38 83-00 47°82 19:90 21°35 84°91 49°51 20°54 21°88 86-06 50°26 21-29 23°58 86-59 50°87 22:01 23°72 87°16 51-80 22°72 26°26 87°61 52°32 25°17 88°15 54°02 27-07 88°77 53°51 27°83 89-28 56°78 28°87 92°02 57:02 30:73 92-58 57-95 32°19 93°16 58-43 34-50 93°66 59°80 35°48 94°18 61-69 35°91 94°84 61°88 36°84 95°21 63°31 37-64 96°67 63°93 38°37 98-86 64°36 39°55 99°39 65-05 40°09 3000°07 67°35 40°37 01-01 71°12 41-92 04°06 71:78 42°85 04°62 72°63 43-14 05-18 73°44 43°83 08-41 73°S4 44°25 10-75 74°96 44°57 11-22 77°00 45°24 11°55 77:40 45°92 13°16 77:93 47°34 13°85 79°47 48°62 15-30 $3°82 48°88 16°63 84°61 49-97 17°66 85°52 50°24 18°63 88-08 52°36 18°96 93°62 53°14 20-79 94°13 53°71 21°67 95°10 54°14 24°48 95°59 64°77 26-80 96°26 55°31 28-25 98-22 58-14 29-29 99-00 59°78 30°39 3102-24 59°97 31°48 03°54 60-24 33°07 03°83 62°54 34°31 07-64 63-92 34°62 08°75 64°49 35°11 09°43 69°33 87°17 11-00 72°21 38-00 12°05 73°68 38°15 13-69 78-87 39°88 14°48 80-80 ‘40°39 15°36 81-52 41-05 15°72 83-42 41°89 ‘16°81 84-43 ApEnEY—Photographs of Spark-Spectra. 247 3186°82 3286°09 3891-50 8482-48 88-10 88°18 93°71 84°35 89-92 91°87 93°99 88°66 90°68 95°55 94°45 94°53 92°30 98°50 95°76 95°13 94°70 3301-35 99°49 95°58 98-09 07°12 3402°58 95-80 99-98 07°85 03°43 3502-43 3200-55 08°24 08-91 03°58 01°38 10-80 10°71 10°64 02°64 12°04 11°83 11°94 03°66 12-31 21°36 13°24 05°23 13°19 21°58 22°43 08-10 14°19 22-86 27-44 08°72 14°68 26:21 48°97 09°32 15°42 28°88 50°82 09°87 16-62 28°94 52°51 11°45 22°86 30°61 52°87 11°57 23°68 33°44 68°83 12°64 24°21 33°74 62°64 12°98 24°47 34°12 64°14 16°66 26°73 34°88 64°94 17°55 28°49 35°83 65°54 19°26 83°00 36°16 66°34 19°83 35°45 41°12 73°00 25°50 86°45 41°43 73°81 26°45 37°10 43°80 74:19 29°39 39°11 44:42 74°66 30°00 39°91 45°03 74°99 31-76 42°71 45°60 77°30 34°15 43°49 46°24 78°84 35-30 44°63 46°88 83-54 37°82 46-11 47°23 84°54 38°19 46°83 47°58 85°33 38°88 47°97 51°00 85°53 40°25 49°16 53°46 87°42 44°30 49°45 65°13 93°62 45°65 49°82 55°76 97°79 47°61 50-19 57°76 99°54 49-62 51°65 58°21 8601-85 50°83 52°10 69°41 02°78 51°82 53°26 60°46 05°48 51°92 57°51 63°66 08:56 52°57 58°62 64°06 09°64 56:41 60°48 65°36 10°19 57°91 61-96 67°21 12-76 58°89 63°87 67°86 13°34 60:05 67°60 68-96 15°79 60°81 68°20 69-76 17°50: 61°81 68°90 70°66 18°55 64-40 69°20 72°31 19°55 66°42 (By 73°01 24-79 69°23 75°12 73°81 26°29 69°95 76°45 74°53 28°26 70°28 78°46 75°31 29-66 73°06 79°50 81°41 31°71 76°01 / 79°95 81:73 31°85 83°17 82:77 82°03 82°93 248 Scientific Proceedings, Royal Dublin Society. 3634:17 3732°24 8849°53 4001-61 34°78 37°54 49°66 02°48 30°13 38°62 50°19 03°50 35°48 43°19 52°30 04 01 36°73 43°74 52°69 12°68 38°89 44-09 54°38 14°64 39°95 44-70 54°95 92°47 40°63 47°46 55-41 23°95 41°73 48°78 65°74 24°71 43°01 49°18 56°46 25°21 44°87 50°79 Oat 26°36 45°84 54:68 64°69 27-30 i] 46°39 57°36 74°55 30°90 47-56 57-82 75°41 38°22 48-31 58°19 75°73 39-28 48-76 62-05 79°39 44-29 49°18 65°46 83°45 47°35 50°56 65°69 85°35 48°98 51°89 67°61 86:96 49-38 54°14 68°44 90:96 51°59 56°44 68°92 92°08 52°04 58°39 83°33 94°16 53°35 61°64 88-91 97:91 56-30 63°19 89°85 3903-03 58-98 63°42 90°38 03-31 61°86 65:17 90°58 05°78 62°86 66°19 91-52 08-89 67°14 66°39 92°31 14:29 67°91 66°87 93°45 15°83 71-138 68°10 94:03 16:03 76-52 76°51 94°77 16°30 17°89 17°88 97-29 19:05 82°69 78°06 97-85 21-05 4109-87 79°26 3805-04 22°95 11-26 79°96 07:07 25°35 15-08 81:07 08:15 26°91 20°83 81°71 09°74 28°86 21°55 83°61 12°46 33°81 Ca 33°83 22-04 84°46 14-21 41-50 29°34 85°07 14°81 48°33 23-64 85°73 15-61 63°73 26°74 86°89 15°83 66°45 97-14 88°47 16°38 68°57 27-46 88°87 17:98 69-16 97-91 89°57 18-71 69°85 28-71 89°87 19°83 71-39 31-61 96:96 20°71 76-80 34-83 98°20 21-01 78°87 45-95 3710-41 21-78 79°72 49-55 11°61 23-73 81-45 54-65 13°20 25-60 84-05 61°61 15°46 26°64 84-51 63-79 15°65 30-18 90°11 65:67 16:75 31-16 91-30 69-69 17-45 34°86 91-83 69-99 18°45 36-23 93-08 70-31 23°78 41°42 98°96 7296 31°01 49-01 99-86 75-03 ApvrEnrY— Photographs of Spark-Spectra. 249 4175-39 4261-54 4340-29 4489-66 76:14 62°10 44°74 91-93 79-48 63°37 47:04 92°45 86-41 67:09 - 51:28 95°53 91°52 69-08 52-01 97-05 92-31 69°51. 59-83 4500-49 92-68 70-08 63°35 01-30 93-90 71-24 71-50 02-07 95-16 74:15 73°49 0711 95-70 75-00 74:37 12°16 97°36 75°86 75°54 14-67 98-76 77-29 77:04 15°66 4200-38 80-65 77°79 21°35 03-86 84-43 81:39 94-99 04:73 85:08 83-16 26°77 07-68 89:96 ~ 84:19 27°69 08-62 92-16 87°73 30-01 09°57 93°62 86°24 30-99 09-94 95-82 4403-68 33°31 11°51 97-16 £9°94 35:99 12°51 97-80 10°44 39-99 12-78 99-80 11-21 40°79 16-60 99-95 12-49 40°99 17-80 4300-60 12°96 41°79 21°75 01-44 14-02 42-89 23-04 05°55 24°51 44:16 24°81 07°75 32-41 44-85 25-06 09°17 55:27 45°44 25-76 12°68 58°81 46-19 26°76 23-79 | 59-99 54:11 40-86 25-29 | 65°55 55:07 42°58 27-38 | 76°51 56°43 52-95 37°81 | 80-45 58-92 54-51 39°68 83°07 55°70 39°93 | 87°25 eon XXV. THE PRE-GLACIAL RAISED BEACH OF THE SOUTH COAST OF IRELAND.! By W. B. WRIGHT, B.A., anp H. B. MUFF, B.A., F.G.S. (Puates XXIII.-XXXI.) [Read, Fepruary 16 ; Received for Publication, Marcu 18 ; Published, SrpTEMBER 12, 1904.] ‘ ) CONTENTS. Part I. PAGE PAGE 1. Introduction, ‘ 3 5 | AX) 4. General Account of Raised Shore 2. Glaciation, . : ; 5 Dail Gn an 257 3. Typical Sections, 5 2 BRS 5. General Conclusions, . F 271 Pant IT. Detailed Description of Sections visited between Baltimore and Carnsore Point, . 274 PART I. 1. InrRopucrion. Tur attention of workers on the Pleistocene Geology of Ireland has up to the present been mainly concentrated on the glacial and post-glacial deposits of the country. With regard to its condition immediately before the advent of the ice, little, however, is known. Indeed, it is only in that part of Ireland which has been most neglected by glacial geologists that there existed a condition of glaciation sufficiently feeble for the ample preservation of uncon- solidated deposits laid down prior to the boulder-clay. Such an area was not likely to attract those who, as pioneers in the study of the glaciation of the country, naturally preferred to work in districts where the phenomena were more marked and striking. During the examination of the drifts of Cork by the Geological Survey in the year 19038, some raised-beach deposits, obviously older than any boulder-clay of the district, were found fringing 1 The observations relating to the neighbourhood of Cork Harbour are communicated with the permission of the Director of H. M. Geological Survey. Wricutr anp Murr—Pre-glacial Raised Beach. 251 _ the shores of the Harbour. It was at once recognised that a wider investigation was desirable, and we employed our leisure in visit- ing various points on the south coast at which the conditions seemed promising for the preservation of the beach. The action of the land-ice on the coast from Clonakilty to Carnsore Point has been comparatively feeble ; and where recent marine erosion has not proceeded too far, the beach is in conse- quence well preserved. West of Clonakilty, however, we get too near the Kerry and West Cork centre of dispersion of the land- ice for such preservation to be possible. The rock-shelf of the beach can, however, be traced as far as Baltimore, this being the most westerly point at which search was made for it. Although never properly investigated, the deposits in question did not remain entirely unnoticed by former geologists. In the Geological Survey Memoir, on Sheets 185 and 186, published in 1861, Jukes has a brief but accurate account of the head and raised- beach gravels. On the 6-inch working sheet, No. 99, County Cork, he has a sketch of the section at Ringabella, shown in Pl. XXVII., and the note, “ Small raised sea beach about 8 or 10 feet above ordinary high-water mark.” The sections at Ballymadder Point, County Wexford have already been described by Mr. G. H. Kinahan in the Geological Survey Memoir on Sheet 181. 2. GLACIATION. It is now widely recognised that a large portion of Ireland was, during the Glacial Period, covered by an ice-cap, which had its centre of dispersion somewhere in the neighbourhood of Fermanagh. The ice moved from this centre in a south-easterly direction over Cavan, Meath, Dublin, and Kildare to the east coast. This stream seems to have divided into two on the north-westerly flank of the Wicklow Mountains. The westerly branch went south through Kildare and Queen’s County, and merged witii the stream which passed over Kilkenny into Waterford, where the striee indicate ice-motion from north to south out to sea. The easterly branch was deflected south near Kingstown, and helped to swell the ice which moved in a southerly direction along the coast of Wicklow and Wexford. The cause of this deflection was the existence, in the basin of the Irish Sea, of a more or less inde- SCIENT. PROC. R.D.S., VOL. X., PART II. x 252 Scientific Proceedings, Royal Dublin Society. pendent ice-sheet, which overflowed through St. George’s Channel, and passing across the south-east corner of Wexford, spread along the south coast of Ireland at least as far as Power Head in County Cork. The evidence in the neighbourhood of Dublin tends to show that this ‘ Irish Sea Ice’ attained its maximum development shortly before that of the centre of Ireland.1_ This is borne out by the sections on the south coast at Dungarvan and Ballycroneen (County Cork). In the former place, the marly boulder-clay of the Irish Sea Ice is overlain by that which came from the north; and in the latter, by a boulder-clay similar to that seen around Cork, and which the strie show to have been laid down by ice moving from west to east across the Harbour. This ice apparently had its centre of dispersion in Kerry or West Cork, as striee in a similar direction have been observed in the valley of the Lee at Macroom and Gougane Barra, and there is a gradual swinging round from an easterly to a southerly direction as we proceed along the coast from Cork to Baltimore. It will be seen from these considerations, and on consulting the map (Pl. XXX1I.), that the direction of the ice-motion on the south coast was generally off-shore. The deposits, owing to their posi- tion in the lee of the cliff, were thus protected from erosion by the ice, the action of which, as pointed out above, was comparatively feeble over the greater portion of the area. In order to give an idea of the mode of occurrence of the pre- glacial’? deposits thus preserved, we shall, before proceeding to a general account, describe a few characteristic sections. The first, that in Courtmacsherry Bay, is typical of those areas which the inland ice alone appears to have invaded. The second, in Bally- croneen Bay, is of interest as being within the debatable ground which appears to have been first occupied by ice from the Irish Sea Basin. The third furnishes a proof of the pre-glacial age of the old rock-platform, independent of the mere superposition of the boulder-clay. 1 This result is in accordance with Mr. Lamplugh’s conclusion that the centre of greatest accumulation over the British Isles shifted westward and south-westward during the period of glaciation. See ‘‘ Geology of the Isle of Man’’—Mem. Geol. Sury. U.K., 1903. 2 The term ‘pre-glacial’ is used throughout the paper to signify ‘ prior to the deposition of the boulder-clay of the area in question.’ Wericut anp Murr—Pre-glacial Raised Beach. 209 3. TypicaL SEcTIONS. Section in Courtmacsherry Bay.— Along the greater portion of the northern shore of Courtmacsherry Bay stretches a remarkably smooth platform of rock about 5 feet above high-water mark. At a varying distance from its seaward edge it disappears beneath amass of drift. The drift deposits lie on the water-worn platform, and are banked against a cliff or slope of rock which rises from behind them to a height of 150 feet above O. D. They are packed into the angle between the platform and the cliff, and form a terrace of varying width. About 350 yards east of the ~ Coastguard Station at Howe’s Strand, the drift-cliffs present the following section :— Feet. Upper head (rubble and soil), Ar Hee Boulder-clay, .. 52 fe, SOF: Lower head or rubble- ant at d feapabiel Stratified pebbly raised-beach sand, lying among sub-angular blocks of rock, eta ills Water-worn rock-platform. The succession and relation of the deposits to one another are shown in the following diagram :— Fie. 1.—Diagram of Section in Courtmacsherry Bay. 1. Raised-beach gravel and blocks. 2. Blown sand. 3. Lower head. 4. Boulder-clay. 5. Upper head. X 2 254 Scientific Proceedings, Royal Dublin Society. The rock-platform is cut across the edges of the highly inclined black slates and sandstones of the Carboniferous Slate series. It has a smooth, water-worn surface, sloping gently seaward, and at its outer margin drops more or less steeply on to the modern shore. It is raised about 5 feet above high-water mark of ordinary spring-tides. The blocks which lie on the platform embedded in the beach- sand sometimes attain a length of 10 feet. They are sub-angular, and even rounded in form, and have obviously been subjected to a certain amount of erosion by wave action. They are of similar nature to the rocks in the pre-glacial cliff above, having fallen from it during the formation of the beach. They probably mark a period when undercutting of the cliff was still in progress. The raised-beach sand rests on the wave-worn platform, and consists chiefly of small oval flakey bits of the local black slate, lying flat, and cemented by oxides of iron (‘ferricrete’). The pebbles occur in rows in the sand; all are well rounded, and most of them consist of vein quartz. The whole deposit is well stratified, and obviously water-sorted. The blown sand overlies the beach-gravel and blocks, and is banked against the old rock-cliff, behind the head, which has obviously slipped down little by little over it. The sand is tolerably free from admixture of rubble: The lower head consists of fragments of black slate and angular lumps of vein quartz. The slate fragments are all perfectly angular, and are bounded by cleavage and joint planes. Consequently the common shape is that of slabs or plates which lie flat in the deposit, and impart a sort of rude stratification to it when seen from a distance. The boulder-clay is a stiff, grey, unstratified clay, containing a variety of stones which lie in all positions in it, and have been derived from the Carboniferous Slate and Old Red Sandstone. The boulders exhibit different degrees of rounding, and the harder ones are often striated. The upper head is, like the lower, composed of angular slate fragments, but also contains a small number of sub-angular and rounded stones. A. short distance from the section described above, a stack Wricur anp Murr—Pre-glacial Raised Beach. 255 about 10 feet high stands on the raised-shore platform, and exhibits the following section :— Feet Boulder-clay, 5.6 56 Bom ge: Lower head, as <4 Oo Black sand and Pebbles (of slate and quartz) in lines, .. ah sa Lee Platform. It now stands about 5 yards from the cliff, and shows that at one time the drifts covered a considerably larger extent of platform than at present (see Plate XXIITI.). It is worth noting in this connexion how seldom any erosion of the drifts is effected by the waves. Vegetation often obscures the cliff to its very base, and even spreads out on the platform, which is always overgrown by lichens (see Plate XXVI.). It seems to be swept by waves only at high tide during storms with an on-shore wind. The superposition of the boulder-clay proves the pre-glacial age of the lower head and raised beach. The lower head, in its turn, marks a period before the oncoming of the ice, when debris from the old sea-cliff accumulated on the beach, after it had been raised above the reach of the waves. The occurrence of blown sand close down to the rock-platform indicates that eleva- tion commenced before the head began to accumulate. Three-quarters of a mile to the east of the section just described, where a road descends on to the shore, the section in the cliffs is as under :— Feet. Boulder-clay, .. we =e 56, 2D Sand and gravel, Ai a rag itil Rock-platform. — At the base, and resting on the platform, there is a thickness of 3 feet of coarse gravel, which is succeeded by beds of fine and coarse sand, with layers of well-rolled pebbles. Not only is the sand sifted into beds of different degrees of coarseness, but the pebbles are fairly well sorted into sizes. A few pebbles of distant origin were picked out of the gravel (see p. 261). The boulder-clay is of a greyish colour, and contains numerous small pieces of slate as well as larger striated stones, all of which 256 Scientific Proceedings, Royal Dublin Society. seem to be derived from the Carboniferous Slate and Old Red Sandstone. Although’ the section at this point is incomplete, it is, perhaps, the finest exposure of the beach-deposits on the coast (see Plate XXIV.). Section in Ballycroneen Bay.—Hast of the Coast-guard Station in Ballycroneen Bay, the following section can be made out :— Feet. Reddish clay and stones, a ota gal \ Fine loamy sand with stones, as cero: | Marly boulder-clay, ie be “iy 20 Head, ae ue Bs 6-12 Rolled gravel and sand, Le wae pee Platform. The marly boulder-clay is a tough, greenish-grey clay con- taining shell fragments, and small stones of local and distant origin. It is overlaid by a very fine loamy sand with numerous angular and sub-angular local stones and a few rounded erratics. Above this, and graduating into it, is a red, sandy boulder-clay, similar to that of Cork, which, as pointed out above, has been deposited by ice coming from the west. The marly boulder-clay, on the other hand, can be traced eastward into County Wexford, and thence northwards to the neighbourhood of Dublin, being undoubtedly the boulder-clay of the ‘Irish Sea Ice. The “West Cork Ice’ seems to have advanced over ground once occupied by the ‘ Irish Sea Ice’; this overlapping of the charac- teristic boulder-clays of these sheets taking place along a limited area near their junction. The section shows clearly that the beach-deposits and head were formed prior to the occupation of the ground by the ‘ Irish Sea Ice.’ Section in Ringabella Bay.—An extreme modification of the cliff-sections arises when all the deposits are eliminated but the boulder-clay. It thus comes in contact with the platform which is glaciated beneath it. On the north side of Ringabella Bay the platform attains a width of 40 to 60 yards, and has a remark- ably level surface. The boulder-clay, which is banked against the cliff behind, thins gradually seaward for a distance of 20 or 30 Wricut and Murr—Pre-glacial Raised Beach. 257 yards, where it ends abruptly in a small cliff 3 or 4 feet high, leaving the rest of the platform uncovered. The surface of the rock is beautifully polished and striated, and forms a remarkable contrast to the water-worn appearance it usually presents. The striae run in an approximately eastern and western direction, nearly parallel to the shore, so that they could not have been formed by soil-slip, even if their nature were such as to render this expla- nation possible. Thus, the proof of the pre-glacial age of the platform does not depend merely on the superposition of the boulder-clay (see Plate XXV.). 4. GENERAL AccouNT OF THE RatsED-SHORE PLATFORM AND OveRLyING Deposits. The most persistent relic of the raised-beach period is the buried rock-cliff and shore platform. The platform, as already described, presents a smoothed, slightly undulating surface, which slopes seawards from the foot of the buried cliff, usually at angles varying from 3° to 10°. Where the inner margin of the platform ig exposed, it is rounded off into the cliff, and the wave-worn sur- face of the platform is prolonged 3 or 4 feet up the face of the cliff. This feature, it need hardly be pointed out, is to be seen everywhere on a modern shore where the sea washes the foot of the cliff at high tide. In Courtmacsherry Bay, about 500 yards east of Howe’s Strand Coast-guard Station, the surface of the platform is channelled from north to south by furrows which pass under the ferricrete sand of the raised beach. The furrows run down the slope of the platform across the strike of the rocks, and seldom seem to coincide with a joint or other line of weakness. They appear to have been produced by the washing of gravel and sand backwards and forwards across the shore; but, whatever their origin, it is to be noted that similar furrows are to be seen in many places on the present shore, where the rocks have been cut down to a nearly level surface (see Plates XXIII. and XX VI.). In comparing and contrasting the pre-glacial with the modern shore, it became very evident that on the former the rocks were reduced to a much more uniform level. Hard beds do not stand out so conspicuously ; and stacks and knobs of rocks, so often found 258 Scientific Proceedings, Royal Dublin Society. on the modern shore, are seldom seen projecting above the general level of the pre-glacial one. In two general cases only does the modern shore exhibit as plane a surface as the pre-glacial one; first, when the rocks are very soft and easily eroded ; and secondly, when the seaward portion of the pre-glacial platform forms the modern shore. The cause of this is to be found in the much slower advance of the sea during the raised-beach period. It had then; in extend- ing the upper margin of the platform, to indenenee cliff, in most places over 100 feet high. At the present day it has only to remove the 12 feet, more or less, which represents the difference in level between the recent and pre-glacial shores. The former is, as a consequence, much less mature than the latter ; or, in other words, it is reduced somewhat less below high-water mark at the present day than the pre-glacial platform was below high-water mark at the time of its completion. In measuring the height of the raised-beach it was found impossible to obtain a datum which could be used everywhere and at any state of the tide.. In some places the high water of mean or ordinary spring-tides was available; in others, the upper growth limit of Balanus and Fucus was used; or again, where the rocks have been sufficiently eroded, the inner edge of the present shore-platform was employed. Measurements made from this last line to the corresponding margin of the pre-glacial platform are particularly useful, as they serve to indicate the amount of elevation of the beach. Owing, however, to the want of maturity of the present shore, they are likely to give an under-estimate of the elevation. Near Ballinglanna Cove in Clonakilty Bay the pre-glacial plat- form was found to be about 10 feet above the present shore (see Pl. XXTX.). In a small bay, five furlongs east of Howe’s Strand Coastguard Station (Courtmacsherry Bay), the inner edge of the pre-glacial platform is 10 feet above the corresponding part of the shore-platform ; and a similar difference of level was found a quarter of a mile east of Ballycroneen Coastguard Station. A. number of observations, taken with reference to high-water — at ordinary spring-tides, showed that the exposed part of the pre- glacial platform was generally about 5 feet above this line. Details are given in the sequel. Wricur anp Murr—Pre-glacial Raised Beach. 259 Occasionally a water-worn surface is found at rather higher levels. This may be due to hard beds of sandstone or grit forming the platform, or to a buttress of rock at the foot of a point which projects forward from the pre-glacial cliff. In Powerhead Bay, where the platform is cut in grits with thin slates, it rises at one point to a height of 15 feet above the modern beach-shingle. At the north end of White Bay (Cork Harbour entrance) the pre-glacial beach attains the unusual height of 15 feet above high- water mark of ordinary spring-tides. The beach may be traced east- wards round Carlisle Fort, and southwards towards Roche’s Point, in both of which directions it gradually regains its ordinary level. It, therefore, cannot be regarded as a beach of different age, marking a period of greater submergence. The extraordinary height to which the beach rises in the north- east corner of this bay seems to be connected with the fact that a valley, which reaches the coast here, has on one side of it a broad, terrace-like feature which slopes towards the sea. The beach- gravel, which seems to have been driven up by the waves on to this terrace, might be considered as a storm-beach. Sections near Camden Fort, and again in Courtmacsherry Bay, are noted in the sequel in which the beach seems to have been thrown up above the level at which it is commonly found. In many of the bays the buried cliff recedes inland; and the platform, owing to its seaward slope, sinks to a low level where it is exposed on the coast. West of Simon’s Cove, in Clonakilty Bay, where the platform is about 50 yards broad, the lower half of it is covered at high tide. At Donaghmore, in the same bay, the buried cliff is nearly 50 yards behind the present cliff of boulder-clay and raised-beach shingle. Here the pre-glacial platform forms the modern shore, and high spring-tides reach up to the foot of the drift-cliffs. In Ballycroneen Bay the pre-glacial cliff retreats as much as 200 yards inland. In this case the base of the lower head is below high-water mark, and the cliffs are being worn away at a comparatively rapid rate. When due allowance is made for the formation of storm- beaches and for the recession of the pre-glacial cliff into the drift-filled bays, it is found that the beach maintains a remarkably uniform level. In all the sections visited on the Wexford coast, the beach-gravel appeared to be rather lower than in the western 260 Scientific Proceedings, Royal Dublin Society. sections. As, however, so little was seen of the inner margin of the shore-platform, and as the amplitude of the tide is somewhat greater here than on the Cork coast, it is difficult to be certain on this point. The difference in level between the pre-glacial beach and the modern one appears to be about 12 feet. The beach-deposits consist of stratified gravel and sand commonly cemented into a hard conglomerate or sandstone by oxides of iron (see Pl. XX X.). They vary in thickness from a few inches ie 12 feet. Shingle is usually found near the buried cliff, whilst further sea- wards there is generally a bed of gravel overlain by fine sand or sand with pebbly layers. The pebbles have smooth worn surfaces, and, especially in sections on the open coast, take the form of flattened ellipsoids—a shape characteristic of pebbles subject to continued wave-action on a beach. The sand varies from coarse to fine; but the grains forming any particular bed are of about equal size. T'he sorting of the material into sizes is also noticeable in the gravel. In sections at right angles to the trend of the coast-line, the bedding is often seen to dip seawards at angles slightly greater than the slope of the platform. This structure is particularly well seen in a section 80 yards south of Myrtleville Cottage, Crosshaven (see Plate XX VII.). The section is also of interest on account of Jukes having sketched it on the 6-inch map deposited in the Geological Survey Office, and noted that it was a “small raised sea-beach about 8 or 10 feet above ordinary high- water mark.” The shingle and sand are almost entirely composed of the local rocks. In some places, indeed, the sections were searched. over long stretches of coast without bringing to light any foreign pebbles. In others, however, a small proportion of flints and igneous rocks occurred. The search made was by no means. exhaustive, owing to the very limited time available at each section, nor can the list given below be taken as indicating the relative proportion in different places. It can be definitely stated, how- ever, that at Ballymadder, on the coast of Wexford, which is nearer the outcrop of some of the igneous rocks, pebbles of them are much more abundant. Wrienut anp Murr—Pyre-glacial Raised Beach. 261 List oF ERRATICS FOUND IN THE RaAIsED-BEACH GRAVEL. Clonakilty Bay.—In beach-gravel, beneath boulder-clay, in Donaghmore. Several well-rounded flints from }inch to I inch long. Courtmacsherry Bay.—In beach-gravel, beneath boulder-clay, where a road descends to the shore about one mile east of Howe’s Strand. Grey flint (two specimens). White chert (with crincids).—Carboniferous Limestone. Red granite. Porphyry.—Probably from Silurian area of County Waterford and County Wexford. Pink microgranite or aplite (two specimens).—Similar to veins in Carnsore granite. Ballycroneen Bay.—In beach-gravel, beneath head and marly boulder-clay, 150 yards east of the Coastguard Station. Quartziferous porphyry.—Probably from Silurian area of County Waterford and County Wexford. Pink microgranite or aplite.—Similar to veins in Carn- sore granite. Youghal Bay.—In beach-gravel, beneath head and boulder-clay, at the south end of the bay near Greenland. Grey flint. Felsite.—Probably from Silurian area of County Water- ford and County Wexford. Quartz porphyry.—A rock very like this occurs on road east of Ballyvoyle Bridge, and in Boat Harbour Cove, Stradbally, County Waterford. Andesite, or basalt, with small porphyritic felspars.— A rock similar to this occurs at extreme south-east of Ballydowan Bay, County Waterford. Epidiorite (two specimens).—Probably from schists of County Wexford. Gneiss.—Similar to foliated granite, south of St. Helen’s, County Wexford. 262 Scientific Proceedings, Royal Dublin Society. Ballymadder, County Weaford. Several pebbles of pink microgranite or aplite.—Similar to veins in Carnsore granite. Granite.—Similar to a specimen of granite from Gnert Saltee Island. Porphyritic andesite or felsite (two specimens).—Probably from Silurian area of County Waterford and County Wexford. Flint. The method of transport of these pebbles forms an interesting problem. Dried seaweed floated off the beach has been known to bear stones for long distances; but as a cause for such an extensive distribution it seems rather inadequate. It is not improbable that glacial conditions may have existed further north at the time of formation of the beach, and the temperature may have been sufficiently low for the presence of floating ice, which would form a much more effective carrier.'_ It must be noted in this con- nexion, however, that no disturbance of the beach-deposits such as might be attributed to the grounding of floating ice was noticed in any of the sections. The striations on the rock-platform at Ringabella Bay and elsewhere are immediately overlaid by boulder-clay. Although search was made in the beach-deposits for fossils, none were obtained. Springs commonly issue along the platform through the beach-deposits, and the frequent conversion of the latter into ferricrete, even where no springs issue, testifies to the percolation of much water. This water, escaping as it does from the non-caleareous Carboniferous Slate and Old Red Sandstone, would readily dissolve any calcareous matter in the beach. 1 Tt may be remarked that most, if not all, of the erratics found in the raised beach of the Cork coast have travelled from E.N.E. to W.S.W., i.¢., against both the tidal drift (such as there is) and the prevailing winds of the recent period. It is interesting to note that if an ice-cap, accompanied by more or less permanent anticyclonic condi- tions, had already established itself in Scandinavia, the prevalent winds on the south coast of Ireland would blow from the east and north-east, owing to the shifting south- wards of the track of the cyclones. (See F. W. Harmer, Q. J. G. S., vol. lvii., p. 405, 1901.) * It was implied, in the abstract of a paper printed in the Geological Magazine (Dec. 4, vol. x., p. 501, 1903), that shells had been found in the pre-glacial beach. These wreedl, on further investigation, to be recent, and not to be included in the beach-deposits. Wricut ano Murr—Pre-glacial Raised Beach. 263 Attempts to find the beach-deposits at the foot of cliffs of lime- stone in Cork Harbour and on the Waterford coast were unsuc- cessful. Not far from the limestone outcrop on the west side of Whiting Bay, limestone pebbles, often bored by Saxicava and Cliona, are common in the modern shingle. The pre-glacial beach is exposed in the cliffs, but not a single limestone pebble could be found in it. This seems to point to the complete decalcification of the beach-deposits. The pre-glacial blown sand occurs buried beneath the head (see Plate XXVIII.) and banked against the rock-cliff. Where not cemented by iron-oxides, it is a fine, yellowish, even-grained sand. It often shows bedding dipping gently away from the cliff. Con- eretionary layers are not uncommon. Generally there are a few thin slivers of slate lying along the bedding planes in the upper layers. The matrix of the lower portion of the head is often formed of it; but the line of separation of the sandy head and the blown sand is fairly distinct. As it often lies on the beach- deposits, not more than a foot or so above the platform, it furnishes clear proof that the elevation of the beach commenced before the head began to accumulate. It occurs in places lodged against the cliff at a height of 35 feet above the platform. At the entrance to Cork Harbour, blown sands were most frequently met with in the sections lying between Ringabella Bay and Camden Fort. They also occur near Roche’s Point, but are not as abundant on the eastern side of the Harbour entrance as on the western—a point worth consideration in connexion with the travel of erratics in the beach (see foot-note, p. 262). The lower head, or rubble-drift, is found overlying the raised- beach shingle and blown sand. When the latter are not present, it rests directly on the platform. It consists of angular rock- fragments of strictly local origin identical with the rocks forming the cliff or slope against which it is banked. The cleaved slates and sandstones of the Old Red give rise to a head composed of small slabs, which lie parallel to one another, and constantly dip at low angles away from the cliff. Grit bands naturally afford more or less cubical blocks. The soft, grey slates of the Carboni- ferous Slate series produce by their decomposition a yellow loam mixed with small slivers of slate. The deposit thus varies in composition according to the locality, but there are also varia- 264 Scientific Proceedings, Royal Dublin Society. tions noticeable according to the distance from its source. Close to the cliff are the larger fragments piled up on one another, and lacking the decided parallel arrangement found in other portions of the deposit. Sometimes a loam or sand fills the spaces between the fragments ; sometimesthe spaces are open. This first-formed part of the head is quite comparable with ordinary screes. In the upper parts, and those further from the cliff, the fragments are generally smaller. They are packed closely together, and always dip away from the cliff at low angles. The interstices between the fragments are invariably filled in by loam. Lenticular bands of loam, lying parallel to the fragments, occasionally occur in all parts of the head, but are frequent in the most seaward sections. They often have small slivers of slate imbedded in them. The loam represents the finer material derived from the waste of the cliffs. The bands or streaks in which it occurs, together with the parallelism of the fragments, give an appearance of rude stratifica- tion to the deposit (see Plates XX VII. and XXVIIT_). The accumulation of the head all along the coast is due to the pre-glacial shore platform subtending the base of the cliff, and catching all the material brought down on to it. It probably never accumulated inland to the same extent, owing to the absence of these conditions. The pre-glacial cliff is always rounded off at the top—a feature due to its waste at the time the head was formed.’ The pre- glacial coast-line can be traced by this feature even where the platform and overlying drifts have been entirely removed by recent erosion, as on the greater part of the Waterford coast (see fig. 3). Since there is no head accumulating along the south coast of Ireland at the present day, its formation must indicate a change of climatic conditions. The angularity of the fragments, and their origin from the adjacent heights, point to the action of frequent frosts or rapid alterations of temperature. As already pointed out, the inner portion of the head near the old cliff is quite comparable with modern screes. With respect tothe greater portion of the head, however, the distance to which it extends 1 For the form assumed by cliffs in consequence of disintegration, see ‘‘ On the Disintegration of a Chalk Cliff,’’ by the Rey. O. Fisher, Geol. Mag., vol. 111., 1866, p- 304. Wricut anp Murr—Pre-glacial Raised Beach. 265 _ from the cliffs and its low angle of slope preclude the idea of its being ordinary screes. The materials seem to have been carried out from the cliff; and, on the whole, the finer materials have been moved furthest. Periodical heavy rains washing down the slopes might have effected this. Owing to the superposition of the boulder-clay, it is not easy to perceive the form of the upper surface of the head. Though it generally seems to rise towards hollows in the hills, there is hardly sufficient evidence for stating that it accumulated as a series of cones of dejection. It is, however, to be noticed that a large cone of head, with its apex pointing up a valley, lies on the pre-glacial - shore-platform, just over two miles east of Ballycroneen. The upper head also forms a small cone, resting on the boulder-clay in the middle of Ballycroneen Bay. Its apex is directed up a small valley in the pre-glacial cliff. In order that the head might accumulate, it is necessary for the platform to have been raised beyond the reach of the waves. An elevation of 10 or 20 feet above its present level would have been sufficient to allow of this accumulation. There is difficulty in the way of making any definite deduc- tions from the nature of the head as to what were the climatic conditions at the time it was formed. It is fairly clear that it indicates the action of frost, or of rapid alterations of temperature, in shattering the rocks and forming screes, and of periodic heavy rains in washing the material further from the cliff. It is hard to say, however, whether the shattering action is that due to the expan- sive force of water in a wet climate, or that due merely to rapid and unequal expansion and contraction in an arid climate. The first state, and indeed a condition equivalent to the second, might arise as the result of a great elevation of which the 10 or 20 feet mentioned above may have been only the beginning. There were, however, changes of climate in progress before the uplift began, so that, although it must always be kept in mind as a possible cause of the conditions, it is not at all a necessary nor even a probable one. Other ways in which the required climatic conditions might be brought about can be adduced. A general lowering of mean temperature during part or the whole of the year might cause more frequent frost-action without any other change in the climate. 266 Scientific Proceedings, Royal Dublin Society. It is possible that the cold conditions indicated by the erratics in the beach may have been continued into the head period, and perhaps intensified. A still further intensification may have resulted in the invasion of the area by land-ice. Again, rapid diurnal alterations of temperature might be produced merely by a change of meteorological conditions without any lowering of mean temperature. ‘This would happen if the supply of moisture were diminished during a portion of the year, and a climate thus established with arid seasons, in which sun-heat by day and radiation by night would be very intense. The marly boulder-clay is a greenish or bluish-grey clay, which effervesces freely with acid. Some parts, particularly those of a greenish tinge, exhibit on a surface exposed to the weather, a fine lamination which is frequently contorted. This is well seen in Whiting Bay, east of Youghal. Other parts are compact and sometimes well-jointed. The jointing is very per- fectly developed in the coast sections in the middle of Ballycottin Bay. The marl weathers at the top to a brownish clay, with blue-faced joints. It contains fragments and numerous smaller particles of the shells of marine mollusca, including several northern and Arctic species. List or SHELLS FouND In THE Marty BovuLper-cray.? Ballycroneen Bay. Pecten opercularis, Linn. Astarte suleata, Da Costa. Mytilus, sp. Buccinum undatum (young). Ballycottin Bay. Nuculana (Leda) pernula, O. F. Muller. Cyprina Islandica, Linn. Mytilus, sp. Astarte borealis, Chem. Astarte suleata, Da Costa. Mactra solida, Sow. Tapes, sp. Nucula nucleus, Zinn. 1 We are indebted to Mr. J. de W. Hinch for the identification of the shells. Wricur anp Murr—Pre-glacial Raised Beach. 267 Youghal Bay. Astarte sulcata, Da Costa. Mactra solida, Sow. Tapes decussatus, Linn. Mytilus, sp. Tellina balthica, Zinn. Turritella terebra, Linn. The marl also contains subangular and rounded stones, some of which are striated. ‘They are scattered sparingly throughout it, but are occasionally seen to be more abundant in its upper portion. In this connexion it may be noted that a striated surface has not yet been found beneath the marl along the south coast. ‘The stones are of various sizes; and, in addition to local rocks, include a number of distant origin, amongst which chalk-flints are the most abundant. A series of fine-grained porphyritic rocks, which seem to include quartz-porphyry, felsite, andesite, porphyrite, and dolerite, form the largest class of igneous rock. Some of them are identical with—and others closely approach—specimens of the igneous rocks associated with the Silurian sediments of Waterford, Wexford, and Wicklow. Some gneisses and altered basic igneous rocks (epidiorites) are similar to. rocks cropping out on the shore between Greenore Point and Carnsore, County Wexford.