wGed 9 ¢-4ied od hes as oon Sed eg tecepetes oes = . : Aesetere ep : . . ee Pesettr sie : tits = ft; 4 Co nabetulind mee Tt Sears = pier . soon x Se sort ate “* « Petsteiecetet cetera c an etoters ee ae we habe he Sede sepa 4, ay ees Peis é oar se Ps ; | ree Ae 48 eis 7 ay - 1%, U REPORT OF THE NINTH MEETING OF THE BRITISH ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE; HELD AT BIRMINGHAM IN AUGUST 1839. LONDON: JOHN MURRAY, ALBEMARLE STREET. 1840, PRINTED BY RICHARD AND JOHN E. TAYLOR, RED LION COURT, FLEET STREET. CONTENTS. —— Page Ossects and Rules of the Association .......0++eeee++ sees Vv Memecrs and Couticil ). 0. 5..)..2 5. s\e sine ess ee Rs MEA Ss tp S oc Si vili Places of Meeting and Officers from commencement ........ ib Table of Council from Geinivier acne he, aha Seereaba whe cate ia x Officers of Sectional Committees, and Corresponding Members x1i Pere? SAGCEOUNE Dee. PE. le SRS SAU, Bo GS x1v Reports, Researches, and Desiderata, ........1. 0. cescsere-s XV1 Synopsis of Sums appropriated to Scientific Objects ........ XXIV Arrangements of the General Evening Meetings............ XXvill PUMRMEEOE EHeSENCSIOONE. 3/.'5)400. Sid) Eifyat «8. te Ge eel aid as alone —68 REPORTS OF RESEARCHES IN SCIENCE. Report on the present state of our knowledge of Refractive Indices for the Standard Rays of the Solar Spectrum in different media. By the Rev. Bapen Powe t, M.A.,F.R.S., F.G.S., F.R. Ast.S., Savilian Professor of Geometry, Oxford .................. Report on the application of the sum assigned for Tide Calcula- tions to Mr. WHEwELL, in a Letter from T. G. Bunz, Esq., PUREE fe ete ee ie kG SR eee ISL yo Sh. LS ee YS Notice of Determination of the Arc of Longitude between the Ob- servatories of Armagh and Dublin, By the Rev. T. R. Rosry- 1 SLD ALD EAE Sg boats oe a 2 13 19 iv CONTENTS. Report of some Galvanic Experiments to determine the existence or non-existence of Electrical Currents among stratified Rocks, particularly those of the Mountain Limestone formation, consti- tuting the Lead Measures of Alston Moor. By H. L. Parrin- Some OSGi) aes aa New isnne RMN ROTI as Hide iN AOI GA se Report respecting the two series of Hourly Meteorological Ob- servations kept in Scotland, at the expense of the British Asso- ciation. By Sir Davip Brewster, K.H., LL.D., F.R.S.L. & E. Report on the Subject of a series of Resolutions adopted by the British Association at their Meeting in August, 1838, at New- COSCO eile als va vig 9 noe aoeialete a Celle ss iale c's Steer Report on British Fossil Reptiles. By Ricuarp Owen, Esq., F.RS.; F.G.8., Bee 2th eo eos bidet UE. Giles Bae Report on the distribution of Pulmoniferous Mollusca in the British Isles. By Epwarp Forzes, M.W.S., For. Sec. B.S... Third Report on the Progress of the Hourly Meteorological Re- gister at the Plymouth Dock-yard, Devonport. By W. Snow Fianmrs. BSq., EBs. ss spetine ot ee Bias 0 &ie eine ee Page 25 27 ol 43 127 149 OBJECTS AND RULES THE ASSOCIATION. oe OBJECTS. Tue AssocraTIon contemplates no interference with the ground occupied by other Institutions. Its objects are,—To give a stronger impulse and a more systematic direction to scientific inquiry,—to promote the intercourse of those who cultivate Sci- ence in different parts of the British Empire, with one another, and with foreign philosophers,—to obtain a more general atten- tion to the objects of Science, and a removal of any disadvan- tages of a public kind which impede its progress. RULES. MEMBERS. All Persons who have attended the first Meeting shall be entitled to become Members of the Association, upon subscri- bing an obligation to conform to its Rules. The Fellows and Members of Chartered Literary and Philo- sophical Societies publishing Transactions, in the British Em- pire, shall be entitled, in like manner, to become Members of the Association. The Officers and Members of the Councils, or Managing Committees, of Philosophical Institutions, shall be entitled, in like manner, to become Members of the Association. All Members of a Philosophical Institution recommended by its Council or Managing Committee, shall be entitled, in like manner, to become Members of the Association. Persons not belonging to such Institutions shall be elected by the General Committee or Council, to become Members of the Association, subject to the approval of a General Meeting. SUBSCRIPTIONS. The amount of the Annual Subscription shall be One Pound, to be paid in advance upon admission ; and the amount of the composition in lieu thereof, Five Pounds. vi RULES OF THE ASSOCIATION. An admission fee of One Pound is required from all Members elected as Annual Subscribers, after the Meeting of 1839, in addition to their annual subscription of One Pound. Members are entitled to receive copies of any volume of the Transactions for two-thirds of the price at which it is sold to the public; or by one present payment of Five Pounds, as a fixed Book Subscription, to receive a copy of all the volumes of Transactions published after the date of such payment. Subscriptions shall be received by the Treasurer or Secretaries. If the annual subscription of any Member shall have been in arrear for two years, and shall not be paid on proper notice, he shall cease to be a member. MEETINGS. The Association shall meet annually, for one week, or longer. The place of each Meeting shall be appointed by the General Committee at the previous Meeting; and the Arrangements for it shall be entrusted to the Officers of the Association. GENERAL COMMITTEE. The General Committee shall sit during the week of the Meeting, or longer, to transact the business of the Association. It shall consist of the following persons :— 1. Presidents and Officers for the present and preceding years, with authors of Reports in the Transactions of the Association. 2. Members who have communicated any Paper to a Philo- sophical Society, which has been printed in its Transactiens, and which relates to such subjects as are taken into considera- tion at the Sectional Meetings of the Association. 3. Office-bearers for the time being, or Delegates, altogether not exceeding three in number, from any Philosophical Society publishing Transactions. 4. Office-bearers for the time being, or Delegates, not ex- ceeding three, from Philosophical Institutions established in the place of Meeting, or in any place where the Association has formerly met. 5. Foreigners and other individuals whose assistance is de- sired, and who are specially nominated in writing for the meet- ing of the year by the President and General Secretaries. 6. The Presidents, Vice-Presidents, and Secretaries of the Sections are ex officio members of the General Committee for the time being. SECTIONAL COMMITTEES. The General Committee shall appoint, at each Meeting, Committees, consisting severally of the Members most conver- sant with the several branches of Science, to advise together for the advancement thereof. RULES OF THE ASSOCIATION, vil The Committees shall report what subjects of investigation they would particularly recommend to be prosecuted during the ensuing year, and brought under consideration at the next Meeting. The Committees shall recommend Reports on the state and progress of particular Sciences, to be drawn up from time to time by competent persons, for the information of the Annual Meetings. COMMITTEE OF RECOMMENDATIONS. The General Committee shall-appoint at each Meeting a Com- mittee, which shall receive and consider the Recommendations of the Sectional Committees, and report to the General Com- mittee the measures which they would advise to be adopted for the advancement of Science. All Recommendations of Grants of Money, Requests for Special Researches, and Reports on Scientific Subjects, shall be submitted to the Committee of Recommendations, and not taken into consideration by the General Committee, unless previously recommended by the Committee of Recommendations. LOCAL COMMITTEES. Local Committees shall be formed by the Officers of the Asso- ciation to assist in making arrangements for the Méetings. Committees shall have the power of adding to their numbers those Members of the Association whose assistance they may desire. OFFICERS. A President, two or more Vice-Presidents, one or more Se- cretaries, and a Treasurer, shall be annually appointed by the General Committee. COUNCIL. In the intervals of the Meetings, the affairs of the Association shall be managed by a Council appointed by the General Com- mittee. The Council may also assemble for the despatch of business during the week of the Meeting. PAPERS AND COMMUNICATIONS. The Author of any paper or communication shall be at liberty to reserve his right of property therein. ACCOUNTS. The Accounts of the Association shall be audited annually, by Auditors appointed by the Meeting. Vill REPORT—1839. OFFICERS AND COUNCIL, 1839-40. eS Trustees (permanent.)—Francis Baily, Esq. R. 1. Murchi- son, Ksq. John Taylor, Esq. President.—The Rev. William Vernon Harcourt, F.R.S. G.S. Vice-Presidents.—The Marquis of Northampton. The Earl of Dartmouth. The Rev. T. R. Robinson, D.D. John Corrie, Esq., deceased. President elect.—The Most Noble the Marquis of Breadal- bane. Vice- Presidents elect.—The very Rev. Principal Macfarlane. Major-Gen. Lord Greenock. Sir David Brewster. Sir Thos. Macdougall Brisbane. General Secretaries.—R. 1. Murchison, Esq., F.R.S. Major Sabine, F.R.S. Assistant General Secretary.—John Phillips, Esq., F.R.S. York. Secretaries for Glasgow.—Rev. J. P. Nicol, LL.D. Andrew Liddell, Esq. John Strang, Esq. General Treasurer.—John Taylor, Esq., F.R.S., &c. 2, Duke Street, Adelphi, London. Treasurer to the Glasgow Meeting.—Charles Forbes, Esq. Council.—Dr. Arnott. F. Baily, Esq. R. Brown, Esq. Rev. Dr. Buckland. The Earl of Burlington. Professor Da- niell. Dr. Daubeny. Professor T. Graham. J. E. Gray, Esq. G. B. Greenough, Esq. Dr. Hodgkin. R. Hutton, Esq. M.P. Dr. Lardner. Dr. R. Lee. Sir C. Lemon, Bart. J. W. Lub- bock, Esq. C. Lyell, Esq. Professor Moseley. Professor Owen. The Very Rev. Dr. Peacock. Professor Powell. George Rennie, Esq. Lieut.-Col. Sykes. Captain Washing- ton. Professor Wheatstone. Protessor Whewell. Secretary to the Council—James Yates, Esq., F.R.S. 49, Upper Bedford Place, London. Local Treasurers.—Dr. Daubeny, Oxford. Professor Hens- low, Cambridge. Dr. Orpen, Dublin. Charles Forbes, Esq., Edinburgh. William Gray, jun., Esq., York. William Sanders, Esq., Bristol. Samuel Turner, Esq., Liverpool. Rev. John James Tayler, Manchester. James Russell, Esq., Birmingham. William Hutton, Esq., Newcastle-on-Tyne. Henry Wool- combe, Esq., Plymouth. pesiogle oe ees Ree ATT “Veg ‘gueqsirg ‘WwW cK ag eoereceserseseesereee OW ‘TOISMOIG purqg Ig seeeeerrgareg ‘qo0UVaIyD PLOT [eAUIH-JOle IL teeeeeeeeseeees QupTIepoRy [edioullg *Aoy A10A ssevece seebeuns eRe ser sears “bsq ‘LION a ‘bsq ‘Sureng uyor “ATT ‘TOON “d “f APT ‘bsq ‘Toppy Merpuy "bs ‘19SO 9497104 ‘Sag “Dsq ‘uosspoy ydesor "CW ‘aoysryepg wozhog ‘oa “bsy ‘ayxreg e81005 ‘OW CV IN ‘Woysuyor TOSsazorg ‘SO ‘1079 FT ULAN ‘om “QTY ‘uosuepy uyor *jood1aaryT ‘nonngysuy yesoy ‘sorg ‘toy@AA “N Ydesor "OLLIND VORT[R AA “ULAA "CIN ‘Tke1y, Lossajorg *‘MOpUIAOH] “WT “A “OFST ‘LT toquiaydag ‘monsv1n ‘INVEATVAVAUE JO SINDUVN AHL ATAON LSOW WL "6E8I ‘92 ssndny ‘NVHONIWUIG ‘V'IN ‘LUNOOUVH NONUGA “M “ATY PUL Sige ol oar ae =e: ‘MOSUIqoy ATL “AOY CLAD Seer oerereeseosessseoses YInouwy1V jo [eg oUL scevecesseescccees mo} dure Y}.10 jo stabaeyl CLIN ecccccsece TSW “bsq ‘Kqas uyor xnvoplig 29070 “Cay “ANODIVET WOUIOA “AA “ADI OTL, rere WoT “gy ‘ueying jo doysig ey, eos eeeereeesresseeeeeses ‘OW T]OMOT AA "AN “AOY "SOU “SW “weg ‘uojesq Aotg diy Ig CRORE CER DOCS Ua] “TOYA ‘u0eqd uyor stores oun Gort g OUMION Jo doystg oy], eee eertencecscssee OW “CIN ‘preyog 79) 20 Pee seinen)" i Sa tf ‘greoqAuo0y oO “MW *"AOY “BesT ‘0g ysneny ‘ANA]-NO-TTLSVOMAN 09 “SOU “SU ‘ANVTUGAINNHLYON JO ANN PML "JEQT ‘TT raqmoydog ‘1o0duaArT ‘uo'Ty ‘AIUQ “URyO “S'D'd “S'H'd ‘NOLONITYNG JO TAVA PUL . oe OOO Ee “9E8I ‘Zz ysnsny “TOLSIug op “SM CCW ‘Auaqned, 10sse7org | .........-c-ar-g rojdureysION Jo SMbIR|, OI 09 “SY “'T'O'C ‘INMOCSNYVT JO SINOUVIN PUL ‘SW ‘sory IOssojorg *AOY eeoeereesesceoores oy.) Cony TOMMOTL A AA. "ADT "CES ‘OT qsnsny ‘NTITEAC ‘on ‘purjary Jo [ehoy “uorsy ‘UoyTUMEY “YM Ig Jt “SW “SW “UAozUeUAXG JUNODSTA ‘(TT ‘GAOTT LSOAOUd “ATH PUL T'S Y 99g ‘MOSTGOY UNO Tig | serserrerereesseeess eG ‘MOSUIqOY “YL sou} ‘POQT ‘g aquiaideg ‘HDWAENIAT ‘Op “HW T'SS'W'd ‘Soqtog Iossajorg freee oy “Syd Taysmorg ped ug Jae TSS ad TOA" a 0d ‘ANVESIUE TVINOGOVIN iL US OWA ‘TTOMOT AA. “ULM "AOY LOCC ED OE aU OARS ae 8 “Ta oI[eq. uyor relered 9 "CZ oun ‘TOadlUdNvg "SOU CST CV'W ‘Mopsuapy Jossajorg ‘soy J **'029 ‘Tedoy tomouoysy “sya a ‘AW “a “9D 'SOPCA “SWA'A “VIN ‘MOIMDCATS NVGV “AGH OL OM “SW A OVI ‘TaMOd Tossojorg "Ady | *** 00g [09H “SOG “SW “TOMO AA “AA “ACT "ZEST ‘6I ouNg ‘axosxO 0M “SU “CW ‘Auoqneg stossezorg f° "Op WT SS WA ‘ToysMorg par Ig 09 “SOW “SW “CC ‘AGNVTSNONE “MATH PUL ‘sou “sw ‘dad ees BM canto te Baits { "TEST ‘2% toquiaidag ‘Hu0X ‘gong cunt Keng wey f SOW S Wa WIT noe MouA A Aor om “Sod “SW “TOC ‘NVITIMZLIG TAVE OL *SOTALJIAIBG [CIO *SJUSPISITG-90IA *sJUSpISoIg “JUOULIDUIUIULOD) S}I WOIJ ‘SoTIe}OIDIG jeoo']T pure ‘syuoptsorg-oo1, ‘s}epIsarg YIM “UONRIOOSSY YSU oY} Jo Suyooy JO sou], pue sooe[q oy} Suiaoys a]qey, *] x REPORT—1839. IJ. Table showing the Members of Council of the British Association from its Commencement, in addition to Presidents, Vice-Presidents, and Local Secretaries. Rev. Wm. Vernon Harcourt, F.R.S., &c. 1832—1836. Francis Baily, V.P. and Treas. R.S. ......1835. General Secretaries. 1» “1 Murchison, F.R.S., F.G.S. «esse. 18361839. Rev. G. Peacock, F.R.S., F.G.S., &c. ...1837, 1838. General Treasurer. John Taylor, F.R.S., Treas. G.S., &c. ...1832—1839. Charles Babbage, F.R.SS.L. & E., &c. (Resigned.) R. I. Murchison, F.R.S., &c. Trustees(permanent).+ John Taylor, F.R.S., &c. Francis Baily, F.R.S. Sees dag |) «+ broleasot Whilips, TALS, Segre. 1832—1839. ecretary. Members of Council. G. B. Airy, F.R.S., Astronomer Royal ...... 1834, 1835. Neill Arndt; SNES Ors. cowsd 6 sweep ban ep veeanns 1838, 1839. Francis Baily, V.P. and Treas. R.S. .....+... 1837—1839. George Bentham, F.L.S. .......cscsescccssseseee 1834, 18385. Robert Brown, D.C.L., F.R.S. ...ccsscceseees 1832, 1834, 1835, 1838, 1839. Sir David Brewster, F.R.S., &¢. ....scscscccess 1832. M. I Brunel, FORS., Qer sccaecesss.s sce ivess bGoee Rev. Professor Buckland, D.D., F.R.S., &c. .1838, 1835, 1838, 1839. The Barl of Burlington 2...0.2dse~oeeredwe ax 1838, 1839. Rev. T. Chalmers, D.D., Prof. of Divinity, LC Ho 0bes UP pes swears y Serede Ce eases bac 1833. Professor Clark, Cambridge ..........sseeeeesees 1838. Professor Christie, F.R.S., &c.....c.ccceveensvss 18388—1837. WillrameClitt KAW.) LAGS: ceemcnssstaskmaes 1832—1835. Sohne Gorrie: PONS. (Cs eacesscncce.saccesee een 1832. Professor Daniell, VF R.Sic.ccseesskesecnvccdsavion 1836, 1839. PES Da GNeMY ccuinas ve nain nso eien env sisivec osaeaan 1838, 1839. Vict: MIPIM WALCL. <5 5.2csauswacste esse cosevcusr dees 1834, 1835. The Earl Fitzwilliam, D.C.L., F.R.S., &c....1833. Professor Forbes, F.R.SS.L. & E., &c. ...... 1832. Davies Gilbert, D.C.L., V.P.R.S., &c. «2.006 1832. Professor R. Graham, M.D., F.R.S.E.........1837. Professor Thomas Graham, F.R.S. ..........05 1838, 1839. John Edward Gray, F.R.S., F.L.S., &c....... 1837—1839. Professor Green, F.R.S., F.G.S. .....ccsseeeees 1832. G. B. Greenough, F.R.S., F.G.S. .....000000e 1832—1839. Henry Hallam, F.R.S., F.S.A., &.......0008+ 1836. Sir William R. Hamilton, Astron. Royal of [a ee ee eee Ricoginn ..1832, 1833, 1836. Rev. Prof. Henslow, M.A., F.L.S., F.G.S....1837. Sir John F. W. Herschel, F.R.SS. L. &. E., PAS 5c NGS. eallegecsctatevcdeneae ens 1832. : Thomas slode kin MiP os Rewn-bonas cre pacnsclienor 1833—1837, 1839. Prof. Sir W. J. Hooker, LL.D., F.R.S., &c. .1832. Rev. FW. Hopes BeAG TE LCS. vies -ccsdabacs 1837. Robert Hutton, M.P., F.G.S., &c. ...... eoe-- 1836, 1838, 1839. Professor R. Jameson, F.R.SS. L. & E....... 1833. MEMBERS OF COUNCIL. x1 Rev. Leonard Jenyns .........csccscecsssesssers 1838. Mts hy. CC rs: wscaass os end ccacsewe Se ceWaaduselsstad ete 1839. aut. demon, Bart. MiP.) tecssecssdcacasecenes 1838, 1839. eves. lardnerewianeaust chase ccdacececcrseeans 1838, 1839. Professor Lindley, F.R.S., F.L.S., &. ...... 1833, 1836. Rev. Provost Lloyd, D.D. .........e00s esomcsxe 1832, 1833. J. W. Lubbock, F.R.S., F.L.S., &c., Vice- Chancellor of the University of London1833—1836, 1838, 1839. Rev. Thomas Luby 4. ...0dveccseesescevsssene 1832. Charles Lyell, jun., Esq. .....secesssessescevnees 1838, 1839. William Sharp MacLeay, F.L. s Dbedectebices aces 1837. Professor Moseley ........scscccssesceseersccceeans 1839. Patrhiek Neill, LL D.; FUR.S.By |... cistecdelens 1833. Richard Owen, F.R. S., Waluesecesas aes noniche een 1836, 1838, 1839. Rev. George Peacock, M. A., F.R.S., &c. ...1832, 1834, 1835, 1839. Rev. Professor Powell, M.A., F.R.S., ke... ..1836, 1837, 1839. J.C. Prichard, M.D., F.R.S. RGEGL, sokacnee 50001832. George Rennie, F.R. antic genau bacabc's oeee--1833—1835, 1839. BELO RERME i lvicaicdcacveccatenssvesiosesse 1838. Rev. Professor Ritchie, F. ERE EOr Lin onteeeen meet 1833. Sir John Robison, Sec. R.S.E....csecssesseesees 1832, 1836. P. M. Roget, M.D., Sec. R.S., F.G.S., &c.. 1834 —1837. eNO IIMS CE ane. da Naa seh vsann cnet hale veane cathe 1838. Rey. William Scoresby, B.D., F.R.SS. L.& E.1832. Lieut.-Col. W. H. Sykes, F.R.S., F.L.S., &c.1837—1839. Rev. J. J. Tayler, B.A., Manchester ......... 1832. eeresser Cah NEE IT ccwnndacnconcaceencsce=s 1832, 1833. N. A. Vigors, M.P., D.C.L., F.S.A., F.L.S.1832, 1836. Captain Washington, R.N. ........sscesesescers 1838, 1839. Prabessor Wlicatstane nice. ansadpcnganacesnaseastas 1838, 1839. - EMM WW CWE. cies sccakseadpinsnsiin slp delecas 1838, 1839. Waewia Vauerell, FES, .scnswagsncrcnesaceseess 1833—1836. Secretaries to the Edward Turner, M.D., F.R.SS. L. & E...1832—1836 Council. James Yates, F.R.S., F.L.S., F.G.S....... 1832—1839 Xil REPORT—1839. OFFICERS OF SECTIONAL COMMITTEES AT THE BIRMINGHAM MEETING. SECTION A.—MATHEMATICAL AND PHYSICAL SCIENCE. President.—Rev. Professor Whewell, F.R.S. Vice-Presidents.—Francis Baily, Esq., F.R.S. Professor Forbes, F.R.S. Major Sabine, F.R.S. Secretaries.—J. D. Chance, Esq. W. Snow Harris, Esq., F.R.S. Professor Stevelly. SECTION B.—-CHEMISTRY AND MINERALOGY. President.—Professor 'T. Graham, F.R.S. Vice-Presidents.—Professor Johnston, F.R.S. Richard Phil- lips, Esq. F.R.S. Secretaries.—Golding Bird, M.D., F.L.S. J. B. Melson, A.B., M.D. SECTION C.—GEOLOGY AND PHYSICAL GEOGRAPHY. President for Geology.—Rev. W. Buckland, D.D., F.R.S., Pres. G.S. President for Physical Geography.—G. B. Greenough, Esq. F.R.S. Vice- Presidents.—H. T. De la Beche, Esq., F.R.S. Leonard Horner, Esq., F.R.S. Charles Lyell, Esq., F.R.S. Secretaries.—George Lloyd, M.D., F.G.S. H. E. Strick- land, Esq., F.G.S. Charles Darwin, Esq., F.R.S. SECTION D.—ZOOLOGY AND BOTANY. President.—Professor Owen, F.R.S. Vice-Presidents.—J. KE. Gray, Esq., F.R.S. Dr. Graham, F.R.S.E. Professor Daubeny, F.R.S. Secretaries.—K. Forbes, Esq., M.W.S. Robert Patterson, Esq. William Ick, Esq. SECTION E.—MEDICAL SCIENCE, President.—John Yelloly, M.D., F.R.S. Vice-Presidents.—Dr. Johnston. Dr. Roget, Sec. R.S. Dr. Macartney, F.R.S. Secretaries.—G. O. Rees, M.D. F. Ryland, Esq. OFFICERS OF SECTIONAL COMMITTEES. xii SECTION F.—STATISTICS. President.—Henry Hallam, Esq., F.R.S. Vice-Presidents.—Sir Charles Lemon, Bart., F.R.S. G. R. Porter, Esq., F.R.S. Secretaries.—Francis Clarke, Esq. Rawson W. Rawson, Ksq. W. C. Tayler, Esq., D.C.L. SECTION G.—MECHANICAL SCIENCE, President.—Professor Willis, F.R.S. Robert Stephenson, Esq. Vice-Presidents.—G. Rennie, Esq., F.R.S. Dr. Lardner, F.R.S. Secretaries.—T. Webster, Esq., Sec. Civ. Eng. W. Carp- mael, Esq. Wm. Hawkes, Esq. CORRESPONDING MEMBERS. Professor Agassiz, Neufchatel. M. Arago, Secretary of the Institute, Paris. A. Bache, Principal of Girard College, Phi- ladelphia, Professor Berzelius, Stockholm. Professor De la Rive, Geneva. Professor Dumas, Paris. Professor Ehrenberg, Berlin. Baron Alexander von Humboldt, Berlin. Professor Liebig, Giessen. Professor Girsted, Copenhagen. Jean Plana, Astronomer Royal, Turin. M. Quetelet, Brussels. Professor Schumacher, Altona. BRITISH ASSOCIATION FOR THE TREASURER’S ACCOUNT from RECEIPTS. Set. Gaps. a, Balance in hand from last year’s ACCOUNE ......+.s.eseeeseseerens 670:-—0,,:7 Compositions from 132 Members, Newcastle and since....... = 641 0° 0 Subscriptions, 1838, from 1944 Members, do. ......... dase encea 1944 0 0 Ditto 1839, from 37 do. COs deewsieigevacesodeee 37 0 O Arrears 1837,from 37 do. OW sdenseccs deuce sess ot alO Dividend on £5500 in 3 per cent. consols, 12 months to } 165 0 0 JULY VIASE —“secreccivsevens nb stanecacbnscsearcelsssdctineecnes eal Received on account of Sale of Reports, viz. Ist vol., 2nd Edition ........ eee ee isecsias ack li 2f ee 2NG VOliapensenmen viens Soe Saabsencoscosuieabsoca: seceee, 120 LOM BUG WOl obec .ceessceustcsssss senestearees Scr coanoacene 3 37 13 0 AUD NOlcces steps sxessecbo oc’ > os aeeaa GRE sa oaisRGis oh(v'ns. cle 39 18 6 tDPVOL esespecesonseseeese-necee poeconcnac ancsscancdec- 44 4 4 (HA OLG sancopnans Jaocoasesoseane “oUos Osos SAcododbeeoan- 233 5 8 Lithographs sold .......... Spocasaoomnnncee SQob oat dose SocmoaaSHonage LAGQTG 412 9 6 £3906 11 1 —E—E—E—E—— SS ee ADVANCEMENT OF SCIENCE. lst AucustT 1838 to 15th AucusT 1839 inclusive. PAYMENTS. SEerssa Gd, Expenses of Meeting at Newcastle, allowed by Order of the Council...... 500 0 0 Disbursements by Local Treasurers...........ccscesesccccccescovsccccscccccccecens 156 18 8 Salaries to Assistant Secretary and Accountant, 12 months to aa 250 0 0 Sea MMRINCA a Nee atest Nw dala die dun ctacaive a < Sia an aoh'ac sis civlats adcauiddoun eae suse eee Grants to Committees for Scientific purposes, viz. for Reduction of Stars in Histoire Cé- {1837 21 18 a 17118 6 PE HMEMECE Ets. tascvoatectedebsvedsvecegess 1838 150 0 0 Do. do. Lagailles sccsccenss euensteceeaumr lly Oka) RPMPALORUE OL Stars; 1837 (is .cccnnsesacencensescvesessecsneseens -c- 166 16 6 Land and Sea Level, 1838..............00. deSaiprereceAsencncastic In it eed liey | 2! Do. G0. E857. cectsee Pokus ccucheaetaelesmvureecsads. 222 0 0 Tides’ Discussions at Bristol..........esseseeeseeees =Bancdosopoe -. 30 18 6 MGehaMISM OL WAVES JUSS Z. caascccnenscvecsseecsaislcccesencsn ces 94 2 0 Do. De ee NODS venscasaxnmepanaioemnines hace teteiene tris 50 0 0 Meteorological Observations, Plymouth ...... 40 0 A 55 0 (OO Do. do. hourly, Scotland ...... 15 0 0 SPMPCHNE ANEMOMECHED S600... 002 cececccncececvapidesoedavedsnes 810 0 Meteorology and Subterranean Temp. 1837, Thermometers 21 11 0 SUMEEMIIE PRC AAR 2 ale de onadesstrcsdenserantaasuwsavrascwctetdesanacce 16 1 0 g . 1837. 20 0 0 Action of Sea Water on Iron......... { 1838 20 0 ra 40 0 0 Action of Hot Water on Organic Bodies..........s.ssceessereee 3 0 0 ns ; 1837 5 0 0 British Fossil Ichthyology ............ 1838 105 0 0 110 0 0 HOS SUV REDUNCS ce snsccescesaeceseesesrdenenevn SARC OR Sodan Hod-OSEnORCe 1S 259 Pana SCAN GLC en caisalchvtae silasiia a ailalscieneaesiseisieaiiae sceasas ek tals 50 0 0 Duty of Cornish Steam Engines ..........csescscsceceescncscses 50 0 0 NPG SF SEGAL HN SUN ESS ep ais nn caisintsieciesiiedacmaiias case teobrassel 100 0 0 Experiments on Vitrification (old grant)........seesesesereseees Cs ner Do. OMESELEDL TH OL LOM se. caccscdcscccisassodnssevcssinites 100 0 0 PUBIGIRIESECECHIOUS LOD, ssescacsicecscuisccadtidedesicesccststesses’s 10 10 O Gases on Solar Spectrum, Action Of..........cssescessceevsceeces 22 0 0 Ravwayy Constants. vescc.ecaseoscecssssese 1837 te) ot 98 7 2 2c el elepe ARE ecnee Rodney tuen sates 1838 20 0 0 1595 11 0 Pata sor Printing Reports, Gt Vol. .....ccevscderccescacecceosceces 629 14 OT PON OTAVINES LOT Os utiane eo O.: 0 2. For the Reduction of Teacaille: s ‘Stars, nade the superintendence of Sir J. Herschel, the Astronomer Royal, and Mr. Henderson . Heo .0 0 3. For the Revision of the Nomenclature of the Stars: Sir John Herschel, Mr. Whewell, and Mr. Baily. . 50 O O 4. For the Reduction of Stars in the Histoire Céleste: Mr. Baily, the Astronomer PON and Dr. Robinson. . 328 1 6 5. To extend the Royal Astronomical ‘Society’s S Catalogue: Mr. Baily, the Astronomer Royal, and Dr. Robinson . . . 343 3-6 6. 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Russell, and Mr. XXvii a James Smith... digs 20RL LO a oO 390 O O XXViii REPORT—1839. SEcTION As.) ddoreyi >. £1810 17 «4 —- IBY Sie. Z 141 O O — Cotta dome: 9 Sees BL: 7273 — 15 Sey eee, 8 eee 141 O O — | See 125 0 0 — F - 100 O O — G 390 O O 2789 14.9% The above grants expire at the Meeting in 1840, unless the Recommendations shall have been acted on, or a continuance of the grant applied for by the Sectional Committees, and ordered by the General Committee. Those marked thus *, relating to subjects on which no previous resolution has been adopted, are generally explained at greater length than the others, which are renewals or continuations of former grants for objects which have been detailed in previous volumes. In grants of money to Committees for purposes of Science, the member first named is empowered to draw on the Treasurer for such sums as may from time to time be required. The General Committee does not contemplate, in the grants, the payment of personal expenses to the members. On Monday evening, August 29th, the President, the Rev. W. V. Harcourt, took the Chair in the Town Hall, and de- livered an AppREss to the Meeting (see next page). On Saturday evening, the ConcLuDING GENERAL MEETING of the Association took place in the Town Hall, when an ac- count of the PROCEEDINGS OF THE GENERAL COMMITTEE was read by the Rev. Professor Peacock. ADDRESS BY THE REV. W. VERNON HARCOURT. A. sew weeks since I bade farewell to one whose friendship I owe to this Association, setting forth on an enterprize full of labour and hazard, but full also of such visions of glory, and so brilliant a pro- spect of scientific conquests, that for a mind combining the high aims of the philosopher with the intrepidity of the sailor, no danger, no difficulty, no inconvenience seemed to exist, even in those regions where Stern famine guards the solitary coast, And winter barricades the realms of frost. We sat down, Gentlemen, before his chart of the Southern Seas, and the unapproached pole of the earth: he showed me his intended track ; he pointed out the happy coincidence of the recent discovery (one of the debts which science owes to commerce) of two small islands in those seas; he put his finger upon the spot which theory assigns for the magnetic pole of verticity, corresponding to that which he had himself discovered in the opposite hemisphere, and so situated, inter- mediately between the two newly-discovered insular stations, that should he not reach the pole itself, they would enable him to verify or correct the theory ; and again, on the spot where his course would cross the point of maximum intensity which the same theory involves. We next reviewed the places at which he is commissioned to plant, on his way, three magnetical and meteorological observatories,—St. Helena, the Cape, and Van Diemen’s Land, and those at which he himself especially wished to observe,—at Kerguelen’s Land, New Zealand, and other stations on the land and ice; and we talked of all these as part only of a system of observations simultaneous or combined, stretching from one side of the earth to the other, undertaken or promised, through the whole extent of the British empire, from Montreal to Madras, and blending in co-operation with chains of observatories established, or on the point of being established, by other nations in the four quarters of the world. I confess, Gentlemen, I felt, as one of the white and bright moments A 4 of life, such a conversation, at such a moment, with a man, of whom, as he is no longer with us, I may venture to say, that he is worthy of being employed on so glorious a service. When I had bidden him adieu, I had leisure to reflect on the possible consequences of his expedition, and the plan of which it forms a part,— The problem of terrestrial magnetism solved—first, the laws of the changes of its elements detected, their constant parts determined, and the whole proved to coincide with a theory based on a legitimate re- presentation of known facts—then, the lines of its force and direction truly drawn, the deviations predicted, and the corrections supplied— in the immediate view of practical consequences, our ships finding in their compass-needles a more unfailing guide than in the fragile time- piece or the cloudy sky—in the distant horizon of higher and yet more fruitful speculation, the érwe cause of the phenomena—and therein per- haps a completion of what Newton began—a revelation of new cosmical laws—a discovery of the nature and connexion of imponderable forces —all these the possible results of approaching the heights of theory on what may prove to be their most accessible and measurable side. Afterwards I thought of the causes which had conduced to this grand undertaking, which had prompted the British Government to seek these laurels, and cull these fruits of peace, by the outfit of the most important and the best-appointed scientific expedition which ever sailed from the ports of England. Well were the government both prompted and seconded by the science of the country. I saw the apartments of the Royal Society moved by a fresh spirit of energy and zeal; its most distinguished members sacrificing personal considera- tions, and postponing individual to public objects—Committees meet- ing and corresponding, to perfect the instruments of observation, and prepare the plans for observing—distant members, at Dublin and Woolwich, deputed to instruct the observers. It seemed as if the days of Wallis, and Wilkins, and Wren, and Boyle, and Evelyn were revived ; and whom did I recognise, Gentlemen, among those who were thus zealously and effectively employed? Their faces were familiar to me; they were the same men who first proposed the subject, and discussed it together at the meetings of this Association, the same who went from you to call the national attention to it, and had since added to that call all the influence and all the efficacy of the Royal Society. The indi- vidual, again, appointed to command the expedition, and conduct the observations, and those also who were selected to instruct the other observers, who were they? They were not only taken from the ranks of the Association, but they had perfected the instruments of observation, 5 and gained additional experience in observing, during their co-operative labours in its service. When Captain James Ross and Major Sabine, and Profs. Lloyd and Phillips, and Mr. Fox, were engaged in ascer- taining the curves of the magnetic elements across the British islands, with unexampled completeness, they performed a national work import- ant in itself, but still more important as leading on to greater under: takings. But lastly, Gentlemen, whence proceeded that theory which it is the highest object of all this philosophical energy, and all this na- tional liberality to put to the test—the first profound attempt to bring the magnetism of the earth under the dominion of calculation? Let the illustrious author of it speak for himself: “ Several years ago,” says Gauss, “I repeatedly began attempts of this kind, from all of which the great inadequacy of the data at my command forced me to desist.” “The appearance of Sabine’s map of the total intensity, in the 7th Report of the British Asseciation for the Advancement of Science, has stimulated me to undertake and complete a new attempt,”—an at- tempt, Gentlemen, which, whether we consider the importance of its results, or the labour and the strength expended upon it by this great mathematician, reflects high credit on the author of the map, which provided for such a theory numerical expressions, and does honour to the Institution which was in any the least degree instrumental to its production. In what I have been saying, Gentlemen, I have been desirous of pointing to that spirit of co-operation which our meetings have called forth in this country. We see among us at length the novelty of many fraternities of fellow-labourers working for a common cause, on a com- mon plan, with a perfect mutual understanding. This is the only means of advancing the great branches of knowledge in which space is a necessary element, and it is the best security for a constant progress in all. Science, in a country where every man labours alone, has periods of darkness as well as light, and resembles those stars which are seen from time to time to “ pale their ineffectual fires”; but there need be no fear of its decline, there can be no check in its advance, when it de- pends not on the prowess of any single arm, but on the force of its numbers and the order of its array. The system of your meetings, Gentlemen, has brought together things which ought never to be disjoined—the principles of science, with their application to human use. After gathering your first mem- bers from our ancient schools of learning, you passed to the marts of commerce, and are now come to the heart of the manufactures of Eng- land, and look round on all the resources and creations of mechanical AQ 6 art. The theorist and mechanician here meet together to the mutual advantage of both; witness on the one part the instrument now work- ing in the Philosophical Institution of this town*, and almost supplying the place of a constant observer, which is about to measure the force of the wind at every instant of time, at St. Helena, the Cape of Good Hope, Van Diemen’s Land, and near the southern Pole. On the other hand, I may mention an anecdote which shows by how circuitous a route art has sometimes been driven to seek the aid of science. Du- ring the war between France and England, a Frenchman brought with him the discovery of a great chemical philosopher in Paris, to barter for a secret of the English manufactures; not finding in Lancashire the person he sought, he left a message, returned to London, and was imprisoned under the Alien Act; to prison, however, the English manufacturer followed him, obtained his secret and his liberation, made his own fortune, and enriched his country ft. But need I go further than the immediate vicinity of this town for an instance, the most striking on record, of the mighty influence which the introduction of a new principle in science can exercise on all the arts of life? The history of the improvement of the steam-engine by Watt finely illustrates this truth. In the eulogium of that great man lately published, the Secretary of the French Academy has justly and eloquently displayed, by this memorable example, the power which resides in the unaided genius, industry, and patience, of a single indi- vidual, applying his mind to the fruitful application of a scientific truth, and the incalculable extent to which he may promote the welfare of his country, and benefit the whole family of mankind. He has taught us also to reflect “in what an humble condition of life those projects were elaborated which were destined to carry the British nation to a degree of power hitherto unheard off.” But whilst I refer you to this volume, Gentlemen, for an admirable exposition of important truths, I feel myself called upon to state, that the zeal of M. Arago has carried him too far, when it has tempted him to transfer to Watt those laurels which both time and truth have fixed upon the brow of Cavendish. It is far from my views, to draw any comparison between two illustrious names, of which one stands as high in the discovery of natural facts, as the other does in their useful application; but let * Mr. Osler’s self-registering Anemometer. + This anecdote, with the names of the individuals, was related to me by the late Dr. Henry. t Annuaire, pour Van 1839. p. 236. ad ( us hold a just and even balance between genius that rises superior to the pressure of circumstances, and that which reaches to at least equal intellectual heights, unseduced by rank and riches. The Se- cretary of the Academy has not confined himself to taking from Caven- dish the honour of his discoveries, but has cast a cloud of suspicion on his veracity and good faith: he has, in fact, imputed to him, the claiming discoveries and conclusions which he borrowed from others, of inducing the Secretary of the Royal Society to aid in the fraud, and even causing the very printers of the Transactions to antedate the pre- sentation-copies of his paper. Yet this, Gentlemen, is the man to whom, at his death in 1810, one who knew and was competent to speak of him bore the following tes- timony :—“ Of all the philosophers of the present age,” said Davy, «« Mr. Cavendish combined the greatest depth of mathematical know- ledge with delicacy and precision in the methods of experimental re- search. It might be said of him, what, perhaps, can hardly be said of any other, that whatever he has done has been perfect at the moment of its production: his processes were all of a finished nature ; executed by the hand ofa master, they required no correction; and, though many of them were performed in the very infancy of chemical knowledge, yet their accuracy and their beauty have remained unimpaired, amidst the progress of discovery, and their merits have been illustrated by discus- sion, and exalted by time. In general, the most common motives which induce men to study, is the love of distinction and glory, or the desire of power; and we have no right to object to these motives ; but it ought to be mentioned, in estimating the character of Mr. Cavendish, that his grand stimulus to exertion was evidently the love of truth and knowledge: unambitious, unassuming, it was often with difficulty that he was persuaded to bring forward his important discoveries. He disliked notoriety ; he was, as it were, fearful of the voice of Fame; his labours are recorded with the greatest simplicity, and in the fewest possible words, without parade or apology ; and it seemed as if, in pub- lication, he was performing, not what was a duty to himself, but a duty to the public.”—“ Since the death of Newton,” he concludes, “ En- gland has sustained no scientific loss so great as that of Cavendish: his name will be an object of more veneration in future ages, than at the present moment; though it was unknown in the busy scenes of life, or in the popular discussions of the day, it will remain illustrious in the annals of science, which are as unperishable as that nature to which they belong; it will be an immortal honour to his house, to his age, and to his country.” 8 Alas, Gentlemen, for human predictions and posthumous fame! Who could have foreseen that, ere thirty years had elapsed, so opposite a view of the labours and character of this philosopher would pro- ceed from one of the most enlightened of his successors? But for the sake of justice, and because there is no page in the history of expe- rimental philosophy more instructive than that to which this question carries us back, I now ask permission to give equal publicity to a different view, and to offer such a sketch of the great chemical dis- covery of the composition of water, as may perhaps help to eluci- date the truth. According to the statements of this publication, the person who brought the first evidence of the composition of water, by proving that the water produced is equal in weight to the gases consumed in its pro- duction, was Dr. Priestley; the person who first drew the conclusion that water is composed of oxygen and hydrogen, was Watt. Now, the former of these statements has not only no real foundation, but is con- tradicted by the repeated assertions of Priestley himself, who constantly maintained, that in no experiment made with care had he ever found the weight of the fluid produced, equal to the sum of gases, or the fluid itself pure water. The latter, Gentlemen, has no foundation, except in the licence which M. Arago has used, of quoting the words of Watt otherwise than they really stand. Nor can there be a stronger instance of the inconvenience of such translations, than the difference of mean- ing and value in the words thus substituted for each other— hydrogen, for example, put for phlogiston. What is it, Gentlemen, that gives importance to this discovery in the history of science ? Not merely, as has been too popularly stated, that it banished water from among the elements, but that whilst it accounted for an infinite number of phenomena, it introduced into chemistry distinctness of thought and accuracy of reasoning, and led to the gene- ral prevalence of a sounder logic. The prejudice of that epoch was, not to regard compound substances as simple, but to consider un- decompounded substances as compound. ‘The hypothesis, that a prin- ciple called Phlogiston entered into the composition of a great variety of bodies which we now consider simple, had infected the whole of che- mistry. This hypothesis, at first but a conjectural attempt to generalise the phenomena of combustion, gradually made itself a coat of patch- work out of the successive discoveries of half a century, and arrived at playing as many feats in philosophy, as the harlequin in a pantomime. In the very paper of Watt on which this claim is founded, we find, first, inflammable gas, then charcoal, then sulphur, then nitrogen, to be 9 all different forms of the same phlogiston, united with a minute portion of different bases; we find it combining with oxygen, in one propor- tion, to form carbonic acid, in another, nitrogen, in another, water. Its affinities with these bases, and with all the metals, had been deter- mined by Bergman, as well as the relative weights in which it entered into composition: and to complete all, the year before the publication of Cavendish’s experiments, Kirwan had proceeded to give a table of the absolute weights—had computed for instance that fourteen cubic inches of nitrous air contain 0°938 of a grain of phlogiston, and had actually deduced a law for these weights, corresponding with the spe- cific gravities of the metals. You will easily conceive, Gentlemen, the effect on a purely experi- mental science of such a hypothesis as this, and you must add the effect of other hypotheses, equally prevalent, which bestowed similar che- mical affinities on the principles of light and heat. Bergman calcu- lated the weight of phlogiston “ 72 pollice cubico decimali” of hydrogen to be ;2, of a pound, and the weight of specific heat in the same to be ;$, of a pound. His method of arriving at results which have such a face of precision furnishes a very curious specimen of analytical rea- soning. He asswmes—t|st, That charcoal consists of fixed air, alkaline earth, and phlogiston: he ascertains as well as he can the weight of the two former constituents, and calculates that of the latter from the loss in his analysis. 2nd, He assumes that phlogiston exists in tron in the ratio to that in charcoal of their respective effects in phlogisticating, or alkalizing, an equal quantity of nitre ; he determines this proportion, and from the Ist experiment deduces the absolute weight of phlogiston in a given weight of iron. 3rd, He assumes hydrogen to consist of phlogiston, and matter of heat ; he assumes further that the phlogiston in a given volume of hydrogen is proportionate to the phlogiston in the iron from which it is evolved by the action of acids; he deter- mines by experiment what the weight of iron is which produces a given volume of hydrogen, and he concludes from the two data before obtained the absolute weight of the phlogiston; this he subtracts from the total weight of the hydrogen, and thus determines the absolute weight of the matter of heat*. In like manner you find the ideas of Watt respecting the composition of water connected with, and spring- ing out of the idea, that it was reconvertible, not simply into phlogiston and dephlogisticated air, but, by an intimate union of the latter with the principle of heat, into phlogiston and atmospheric air. By such loose * See Bergman ‘ de Attract. electivis’, pp. 413, 440, ‘ de Analysi Ferri,’ p. 24, Opuscula Phys. et Chem. vol. iii. Upsal. 1783. 10 reasoning as this, some of the best chemists of the day were misled, not only as to the direction of their labours, but even the results of their ex- periments. But in Cavendish’s celebrated inquiry into the causes where- by air suffers diminution in a variety of processes then termed phlogistic, it is well worthy of remark how steadily he moves on from truth to truth, on every point on which experiments afforded ground for reasoning, un- fettered by the complexity of the phlogistic theory ; and it is equally remarkable, how loose he sits to the favourite hypothesis to which the rest of his countrymen clung with such persevering tenacity. He, first of all his contemporaries, did justice to the rival theory recently proposed by Lavoisier, and weighed it in equal scales before the pub- lic eye. He alone seemed to understand, as it became a disciple of the school of Newton, the true use of a hypothesis: he valued neither system otherwise than as an expression of facts, or as a guide to future inquiry. He took these opposite hypotheses, and retrenched their su- perfiuities; he pared off from both, their theories of combustion, and their affinities of imponderable for ponderable matter, as complicating chemical with physical considerations; and he then corrected and ad- justed them with admirable skill to the actual phenomena, not bending the facts to the theory, but adapting the theory to the facts. Allow me to give you an instance of this adaptation. Priestley had stated, that he had converted charcoal into inflammable gas by the sim- ple action of the burning lens, and obtained it from pure iron, by the same means, and had drawn the consequence, that iron was composed of phlogiston united to the basis, or calx, of iron, and that charcoal and inflammable gas were pure phlogiston. “I had no suspicion,” he says*, “that water was any part of inflammable air ;” “ yet that water in great quantities is sometimes produced from burning inflammable and de- phlogisticated air, seemed to be evident from the experiments of Mr. Cavendish and M. Lavoisier. I have also frequently collected consi- derable quantities of water in this way, though never quite so much as the two kinds of air decomposed.” <“ Afterwards, seeing much water produced in some experiments in which inflammable air was decom- posed, I was particularly led to reflect on the relation which they bore to each other, and especially Mr. Cavendish’s ideas on the subject. He had told me, notwithstanding my former experiments, from which I had concluded that inflammable air was pure phlogiston, he was persuaded that water was essential to the production of it, and even entered into it as a constituent principle. At that time I did not perceive the force * Priestley on Air, ed. 1790, part 3. sect. 4. 11 of the arguments which he stated to me, especially as, in the experi- ments with charcoal, I totally dispersed any quantity of it witha burn- ing lens, 72 vacuo, and thereby filled my receiver with nothing but in- flammable air. I had no suspicion that the wet leather on which my receiver stood could have influence in the case, while the piece of char- coal was subject to the intense heat of the lens, and placed several inches above the leather. I had also procured inflammable air from charcoal in a glazed earthen retort two whole days successively, in which it had given inflammable air without intermission : also iron filings in a gun-barrel, and a gun-barrel itself had always given in- flammable air whenever I tried the experiment.” “ But, my attention being now fully awake to the subject, I found that the circumstances above mentioned had actually misled me.” “ Being thus apprised of the influence of unperceived moisture in the production of inflammable air, and willing to ascertain it to my perfect satisfaction, I began with filling a gun-barrel with iron filings in their common state, without taking any precaution to dry them, and found that they gave air as they had been used to do;” “at length however, the production of in- flammable air from the gun-barrel ceased, but on putting water into it, the air was produced again; and a few repetitions of the experiment fully satisfied me that I had been too precipitate in concluding that inflammable air is pure phlogiston.” Dr. Priestley afterwards gives an account (Phil. Trans. 1785) of his repeating Lavoisier’s celebrated experiment, in which the decomposition of water was proved by passing steam through an iron tube. “I was determined,” he says, “to repeat the process with all the attention I could give to it; but I should not have done this with so much advantage if I had not had the assistance of Mr. Watt, who always thought that M. Lavoisier’s experiments by no means favoured the conclu- sion that he drew from them. As to myself, I was for a long time of opinion that his (Lavoisier’s) conclusion was just, and that the in- flammable air was really furnished by the water being decomposed in the process; but though I continued to be of this opinion for some time, the frequent repetition of the experiments, with the light which Mr. Watt’s observations threw upon them, satisfied me at length, that the inflammable air came from the charcoal or the iron.” It appears from these statements, and may be still more clearly ga- thered from Cavendish’s ownremarks* in his “ Experiments on Air,” that he not only set Priestley right as to his supposed fact of the production * Phil. Trans. vol. Ixxiv. p. 137. 12 of hydrogen from dry iron, but furnished a theory by which the disci- ples of phlogiston* might nevertheless maintain their ground both in this and other cases. The explanation which his theory afforded in this instance was, that the inflammable air, due to the unperceived moist- ure in the iron filings, or in the air of the vessels, is evolved by the force of double affinities in the following manner—the water, decomposing the iron, combines in part with its basis, and in part with the phlogiston (or dry hydrogen) which it was supposed by hypothesis to contain; form- ing by the one combination the calx, or oxide, of iron, and by the other, inflammable gast. Such a representation was not incompatible with any known facts, and Cavendish had his own reasons for giving it on the whole a preference over that which seems to us so much more plain and reasonable: its fault as a theory was, that it was needlessly hypo- thetical, and that it was part of a system overloaded with a multitude of hypotheses. Lavoisier was the first to introduce into chemistry a juster language and a safer manner of stating facts; he caught sight of a principle which has been since laid down by Davy as a general proposition, and has contributed much to the distinctness of chemical science,—the prin- ciple that every body is to be reasoned about as simple till it has been proved by direct evidence to be compound. To Cavendish, trained in the rules of demonstration, and gifted with a sagacity and clearness of conception beyond his fellows, hypothetical thoughts and expressions were no stumbling-block ; and he seems therefore not to have felt how great an obstacle they present to the general movement of science as it floats upon the tide of a thousand understandings. If the question then be, who reformed the expressions and logic of chemistry, or who furnished the simple terms in which we now state the elements of water? the answer is, Lavoisier; but if it be, who dis- covered and unfolded the most important facts on which that reforma- * That Watt derived from Cavendish his views on this subject, is evident from the parenthetical introduction of his altered opinion that inflammable gas was not pure phlogiston, but a combination of phlogiston and water, in the middle of experiments and arguments to prove the contrary, without assizn- ing any reason, and after the publication of Cavendish’s theory. See Mr. Watt’s Thoughts. Phil. Trans. vol. lxxiv. p. 330. + Cavendish assigns as his principal reason for believing inflammable gas to be a compound of this description, that it does not unite with oxygen at common temperatures; but it is likely that he was influenced also by the re- sult of his experiments on ‘‘ a different kind of inflammable air, namely, that from charcoal,” for which, see Postscript, p. 38. 13 tion relied? who detected and proved the composition of water, and deduced the train of corollaries which flowed from it? the answer is, Cavendish. The discovery was not one of those which was within every man’s reach, especially in an age of loose experiment and inconclusive reasoning : it was one which could never have been made, but by a strict appreciation of quantities, and a careful elimination of the sources of error: it formed part of the solution of the difficult problem, which at that time occupied the attention of all the chemists in Europe—the cause of the diminution of atmospheric air, in six several cases—in the passage through it of the electric spark, in its burning with hydrogen, in its contact with nitrous gas, in respiration, in the inflammation of phos- phorus and sulphur, and in the calcination of metals. These pheeno- mena had been accounted for by a supposed phlogistication of the air, and a consequent formation and absorption of carbonic acid; Lavoisier stood alone in attributing the phenomena of the four last classes to their true cause. When Cavendish took up the problem, he began by proving that no carbonic acid was necessarily produced in any of these processes: and then, Gentlemen, he turned to use a well-timed but in- correct experiment of an inhabitant of this town, (Mr. Warltire,) and he made it the basis of a series of analytic and synthetic researches, unequalled then, and never since surpassed, by which he demonstrated, as a means of arriving at the solution of his problem,—I1st, The quan- titive composition of the atmosphere; 2nd, The combination of hy- drogen with oxygen and the quantitive composition of water; 3rd, The chemical union of nitrogen with oxygen and the constitution of nitric acid. From these experimental data he deduced the true causes of the diminution of the air in the burning of hydrogen, and in the passage of the electric spark; he adopted Lavoisier’s conclusion re- specting the burning of metals and other inflammable matters, gave the true account of the composition of the nitrates of potash and mercury, explained the constitution of vegetable substances, and the origin of the oxygen which they exhale, and finally corrected the pre- mature generalization which had led the French philosopher to con- sider that gas as the principle of acidity. Such, Gentlemen, were the splendid results of this investigation, such the reinforcement which Cavendish brought to the nascent reformation of chemistry. Equally worthy of observation were the means employ- ed to obtain them. The experiment to be made was the combustion of hydrogen with common air; or, as it proved, its combination with the proportion of oxygen which the common air contained. Now this latter was then a quantity imperfectly known. Hence those analyses 14 which he made in 1781, of the atmosphere under all circumstances, at different times of the day, in town and country, in summer and winter, by which he determined its composition more accurately than any of his contemporaries, and with a precision which has scarcely since been exceeded: thus, with a knowledge of the specific gravities of the gases, and of the weight of common air, he was in a condition to have com- pared the correspondence of the weight of the gases consumed in the combustion, with that of the fluid produced. But this experiment had a weak side, in the practical difficulty of collecting the fluid: he therefore took a more certain method of examining the question by volume instead of weight, by ascertaining whether the production of the fluid was accompanied by the total disappearance of the com- bining gases: to a given bulk of atmospheric air, he added, in success- ive experiments, a gradually decreasing volume of hydrogen gas, and found a point at which the computed volume of oxygen entirely disappeared. But there was yet a possibility of error: the fluid produced might contain something besides water: he analysed it, and found that the water was pure. Not yet satisfied, he repeated the ex- periment in a simpler form, by burning the hydrogen with oxygen, in place of common air ; and here a difference little to have been expected appeared, for, on analysing the fluid he found it to contain not water only, but nitric acid ; he traced the acid to its source in the small portion of atmospheric air with which the gases chanced to be contaminated, and inferred that the oxygen and nitrogen which it contains, unite under certain circumstances to form nitric acid. Thus he was led to the dis- covery of the cause of its diminution when traversed by the electric spark, and from the residuary defect of the experiment he completed the solution of the problem. The experiment by which Cavendish had in 178] ascertained the con- version of oxygen and hydrogen into water, Priestley repeated in an imperfect manner in 1783; and since it is éiis repetition which M. Arago has mistaken for the first proof of the composition of water, listen, Gentlemen, to Priestley’s own preface to the account he gives of it: “ Still hearing,” he says, “ of many objections to the con- version of water into air, I now gave particular attention to an expe- riment of Mr. Cavendish’s concerning the re-conversion of air into wa- ter, by decomposing tt in conjunction with inflammable air.” He then relates the precautions he took in repeating this experiment, expresses his wish that he had a nicer balance, and tells how he collected the fluid by wiping the inside of the glass with filtering-paper; but it does not appear, either from his own statement or the still more particular 15 one furnished by Mr. Watt, that he examined the nature of the fluid. Experiments thus conducted could not, and did not, lead to any solid conclusion; Watt suspended his judgment upon them for a twelve- month, and seven years afterwards, we find Priestley expressing himself thus: “ J must say, as I did when I was myself a believer in the decomposition of water, that I have never been able to find the full weight of the air in the water produced by the decomposition.” And again: “ Having never failed, when the experiments were conducted with due attention, to procure some acid whenever I decomposed dephlo- gisticated and inflammable air in close vessels, I concluded that an acid was the necessary result of the union of these two kinds of air, and not wa- ter only*.” Compare these statements, Gentlemen, which have stood on public record for half a century, with those of M. Arago, affirming that Priestley was the first who proved, and Watt the first who understood, the conversion of air into water, and ask yourselves, how it is possible in the face of such evidence to sustain a charge against Cavendish, Blag- den, and the printers of the Royal Society’s Transactions, of con- spiring to steal a discovery thus acknowledged to have been derived from Cavendish, and of which the truth, recognised for a moment, was im- mediately afterwards denied by Priestley, and doubted of by Watt. In doing this justice to an injured name, I have been led to speak of one whose numerous discoveries attracted in those days the eyes of all Europe to Birmingham, and who deserves to be admired not more for his inventive fertility and indefatigable industry in experiment, than for the honest candour with which he related every fortuitous success and extraneous hint, and the liberal profusion with which he scattered his gold abroad for public use, as fast as he drew it from the mine. It has been one of the charges, Gentlemen, against this Association, that an analysis of the character of Priestley formed a part of its early transactions : that character, drawn by a hand no less judicious than skilful*, regarded science alone, and contained not a single particle of political or polemical alloy: if it had, being in the chair when it was read, I should have felt it to be my duty to interfere. Much more would I myself avoid the touching from this chair on any topic which should have a tendency to excite feelings alien to owr pursuits, and de- structive to all social union: but whilst I can well bear to hear our meetings upbraided with such faults as these, there is one point of attack on which I think I ought not to be silent, even though it stands close on the boundaries of those subjects which I would most rigidly exclude. * The late Dr. Henry. 16 On my own judgement alone I should scarcely venture to meddle with so arduous a question, did I not see those around me who desire it at my hands, as required by the position in which the Association stands. A century and a half ago the Royal Society met with opponents si- milar to those whom the Association has to encounter now. “ Their enemies,” says Dr. Samuel Johnson, ‘“ were for some time very nume- rous and very acrimonious, for what reason it is hard to conceive, since the philosophers professed not to advance doctrines, but to produce facts, and the most zealous enemy of innovation must admit the gradual progress of experience, however he may oppose hypothetical temerity.” They were assailed, Gentlemen, with jokes as well as libels; but there is reason even in ridicule ; and, on this subject, the irony of Butler himself is forgotten ; but there was also a graver class of men in those days, who saw in the establishment of the Royal Society injury to re- ligion ; their names and publications have perished, but the memorial of their apprehensions is embalmed by a writer* whose early history of the Society has been described by his great biographer as “ one of the few books which selection of sentiment and elegance of diction have been able to preserve, though written upon a subject flux and transi- tory.”—“ I will now proceed,” said the episcopal historian, “to the weightiest and most solemn part of my whole undertaking,—to make a defence of the Royal Society and this new experimental learning, in respect of the Christian faith; and Iam not ignorant in what a slip- pery place I now stand, and what a tender matter I am entered upon; I know it is almost impossible, without offence, to speak of things of this nature, in which all mankind, each country, and now almost every family, disagree. I cannot expect that what I shall say will escape misrepresentation, though it be said with the greatest simplicity, while I behold that most men do rather value themselves and others on the little differences of religion than on the main substance itself.” He then thinks it necessary to employ thirty-three pages in defending the inductive philosophy against the charge of impiety, and concludes with this caution,—“ that, above all, men do not strive to make their own opinions adored, while they only seem zealous for the honour of God.” These are bygone days, and Time, Gentlemen, which seems to have little effect in removing prejudice, makes great changes at least in cir- cumstances: the philosophy thus early dreaded has since extended it- self on every side; science pervades our manufactures, and science is penetrating to our agriculture; the very amusements, as well as the * Spratt, Bishop of Rochester. Mi conveniences, of life, have taken a scientific colour. In these altered circumstances, were any now rash enough to kindle the dying embers of this obsolete bigotry—to stir up a worse than civil war between the feelings of piety and the deductions of reason, to go forth with the “ argumentum ad odium” for their only weapon, against a host of facts patiently ascertained, and inferences fairly drawn ;—were they to call in the Scriptures to supply their defects, and fasten on ¢hem their own crude and ignorant speculations—were they to be seen shifting their ground from one false position to another, all equally untenable, and all assuming to be the sole defences of the true faith,—what would be the natural consequence of a warfare at once so offensive and so hope- less? what the effect of so many baffled aggressions and self-inflicted defeats? what the fruit which the tree of knowledge would bear, thus injured, in the name of religion, by men who should remove the boundary marks of faith and philosophy, and confound things human and divine? There are, indeed, certain common points in which reason and reve- lation mutually illustrate each other; butin order that they may ever be capable of doing so, let us keep their paths distinct, and observe their accordances alone ; otherwise our reasonings will run round in a circle, while we endeavour to accommodate physical truth to Scripture, and Scripture to physical truth. The observation of the true points of accordance in such lines, is one of the most instructive of all studies; and when combined with an honest observation of the discordances also, leads to important conclu- sions. - There are many branches of inductive inquiry through which these parallel lines may be drawn, and their accordances observed. Thus Sir Isaac Newton has deduced from the history of inventions, the spread of nations, and the present amount of population, that the time for which mankind have existed cannot materially differ from that usually assigned from Scripture. Geology, with less distinctness, points to- wards the same conclusion. But there are lines of accordance and dis- cordance within the Scriptures themselves. Now, in drawing these lines for human chronology, we find discordances between different versions of almost equal authority, and ¢haé to sueh an amount, that while the Hebrew gives 1948 years for the epoch from the Creation to Abraham, the Greek assigns for the same period 3334; and this differ- ence of nearly 1400 years lies not in a single sum, but is divided among successive generations. For the first seven centuries, the larger com- putation was exclusively followed ; for the last four, the whole Western 18 Church has adopted the less. Do these discordances undermine the authority of Scripture? Do they shake—has any one imagined them to shake—the substantial credit of its history of mankind? Yet it is plain that, in its present condition, Scripture does not teach with cer- tainty and exactness the computation of time. The book of Genesis is not then a book of chronology: it is a book which, by a series of ge- nealogies, traces back the various races of men to one common source. Now, in this point, all the versions, and both the volumes of Scripture, concur—to this point all the lines of scientific inquiry converge—the analysis of language, the most legitimate conclusions of physiology and natural history, coincide in the fact that the nations of the earth are of one blood. There is nothing vague or doubtful in this. Reason and religion are here in perfect accord. Let us proceed from the history of mankind to the general philosophy of nature. No one, I think, can doubt that those who condemned the Copernican system were justified in conceiving that the Scriptures speak of the earth as fixed, and the sun as the moving body. Every one will allow also that this language is ill adapted to the scientific truths of astronomy. We see the folly of any attempt, on this point, to interpret the laws of nature by the expressions of Scripture: and what is the ground of our judgement? We are not all competent to judge between the theory of Copernicus and those which preceded it ; but we determine against the seeming evidence of our senses, and against the letter of Scripture, because we know that competent persons have examined and decided the physical question. Now, Gentlemen, in Geology we are arrived at the selfsame point; that is to say, a vast body of the best-informed naturalists have examined, by all the various lights of science, and by undeniable methods of investigation, the struc- ture of the earth ; and however they may differ on less certain points, they all agree in this—that the earth exhibits a succession of stratifi- cation, and a series of*imbedded fossils, which cannot be supposed to have been so stratified, and so imbedded, in six days, in a year, or in two thousand years, without supposing also such numerous, such con- fused, and promiscuous violations of the laws and analogies of the uni- verse, as would confound, not the science of geology alone, but all the principles of natural theology. Here, then, is another point of discord- ance: and in both these cases the discordance lies between the language of Scripture and the truths of science. To understand how this may be explained, let us compare the ac- count of creation given in Genesis with that contained in a composition as old, or older, than this oldest of books,—a composition which, car- iol rying us back some four thousand years into the midst of the patri- archal ages, yet breathes a spirit of no vulgar philosophy ; and when it speaks of Him “ who hangeth the earth upon nothing,” who “ maketh a weight for the winds, and weigheth the waters by measure,” might tempt us to seek here, with Hutchinson, for the true system of the uni- verse. In that book, I say, we have the first account of the creation of the world, proceeding, as it were, from the mouth of the Creator him- self. ‘ The Lord answered Job out of the whirlwind, and said, Where wast thou when I laid the foundations of the earth? declare if thou hast understanding. Who hath laid the measures thereof, or who hath stretched the line upon it, whereupon are the foundations fastened, or who laid the corner-stone, when the morning stars sang together, and all the sons of God shouted for joy?” “ Or who shut up the sea with doors, when it brake forth as if it had issued from the womb, when I made the cloud the garment thereof, and thick darkness its swaddling band, and brake up for it my decreed place, and set bars and doors, and said hitherto shalt thou come, and no further, and here shall thy proud waves be staid ?” Take, then, these “thoughts that breathe and words that burn,” and compress them if you can into some true or some fanciful system of science ; teach us where to find “ the house wherein darkness dwelleth,” to “ bind the sweet influence of the Pleiades, and loose the bands of Orion”; explain to us, with respect to one of God’s creatures, what the natural process is by which he “ drinketh up a river and hasteneth not”; and of another, how “ his breath kindleth coals, and a flame go- eth out of his mouth,” and then take credit to yourself for vindicating the truth of Scripture : and when you have thus illustrated a compo- sition, by the side of which, till you touched it, the images of Homer and Pindar seem but as prose, go on—instruct us how to interpret that other most ancient book, recorded, it has been thought, by the very same hand—take that passage of it which drew forth the admiration of heathen antiquity—borrow for your purpose the deepest thoughts of modern science—substitute, ‘‘ Let there be ether, and there was ether,” for “ Let there be light, and there was light.” Why does this altered expression fall so flat upon the ear ? it is not like the flood of harmoni- ous sound which some of you may have heard from this Orchestra responding to the words—it is not like the words themselves, which pour upon the mind at once all the beautiful irradiation and delightful perceptions of light: and yet, Gentlemen, after all, you have not even thus perhaps presented a pure scientific view of the act of creation ; for when you have conceived this empyreal ether, this boundless and B 20 all-pervading substance, which vibrates knowledge to our wondering ken out of the unfathomable depths of space, are you prepared to take here your stand? may you not yet find other and still finer links be- yond? and if you should, must not the very form of expression, the instantaneous connexion of the thing made with its Maker,—“ He spake, and it was created ”—become as little scientific, as it is, to the under- standing of all men, superlatively impressive and sublime? You see, Gentlemen, what my meaning is. Had it pleased God to endow the ministers of religious truth with supernatural knowledge of the mysteries of nature, they could not have used that knowledge to any practical purpose ; they could not have used it so as to carry the truths they were commissioned to preserve, into the hearts and imagi- nations of mankind ; and so entirely sensible were they themselves of this, that on subjects thus passing the power of language, they not only meddled not with any system of science, but passed over popular ideas, and the common senses of words, to those highly figurative expressions, which are best adapted to impress transcendental truth. Who, then, would expect to find in Genesis the chronology or se- quence of Creation? who can think that he upholds the authority of Scripture by literal constructions of such a history, by concluding from them that the earth was clothed with trees and flowers before the sun was created, or that the great work was measured by six rotations of the earth upon her axis? It scarcely needed the evidence of physical or geological science to teach us that such a mode of interpreting the sacred writings is utterly unsound: when the same author speaks of man as created in the image of God, every one perceives that this is one of the boldest figures which language can produce ; and in what but a figurative light can we view the days of Creation ? what can we find in such a description but this trath—that the six grand classes of natural phenomena were, all and each, distinct acts of Divine power, and proceeded from the fiat of a single Creator ? Here, Gentlemen, is a second instance of one of those great points of accordance, where all the conclusions of human science coincide with revealed religion, and none more remarkably than that which has been so falsely termed irreligious Geology ; for as Astronomy shows the unity of the Creator through the immensity of space, so does Geo- logy, along the track of unnumbered ages, and through the successive births of beings, still finding in all the uniform design of the same Almighty power, and the varied fruits of the same unexhausted good- ness. Thus, Gentlemen, we have seen in this comparison of two collateral 21 lines of knowledge, certain points of accordance, and certain points of disagreement ; we have seen that Scripture furnishes us with no per- fect chronology of history, and with no chronology of creation except the creation of man ; but we find, also, that it does provide for us, and has evidently aimed at providing for us, from the earliest times to the present hour, the knowledge of two facts: that all men are the children of one human father, and the handiwork of one Almighty God. Here the coincidence is perfect of every line within and without; here the philosophy of Job and Moses, of every prophet and evangelist, agree ; here all the inductions of every branch of science mark the same cor- responding points. And what, Gentlemen, is the common quality of these two facts? Are they not the very facts on which the system of human duty sub- sists, on which humanity and piety depend ? These truths, nursed for a thousand years in the ancient Scrip- tures of the Jews, led forth into new day, and with new accessions of the same kind of knowledge by our holy religion, have walked through the world, and been believed alike by the ignorant and the wise, before our sciences were born: and here observe the methods and the course of Providence ;—how, as in process of years, the current of traditionary belief runs weaker,—how, as the advance of human in- tellect looks for other kinds of proof, the arts and sciences come in to support these essential truths: printing gives them stability and ex- tension ; optics and astronomy pour in an infinity of evidence ; compa- rative anatomy brings up its convictions, and geology subdues the sceptical mind with hitherto unimagined demonstrations. And now, Gentlemen, I think we are in a condition to draw an in- ductive conclusion, and even to hazard a prediction. We may safely predict, that truths thus firmly established by evidence, will never be shaken by the researches of that reason which has hitherto lent them all its support; we may clearly point to that sacred ground on which no unhallowed hypothesis should tread; we are entitled, by the rules of our art, to say to the misnomered philosopher who rashly invades this territory,—These are settled points, settled by every con- clusion of the intellect, as well as by every intuition of the heart: stand aloof! disgrace not the name of Science by throwing stones at the Temple of Truth. But for this assembled body of real work- men, amidst their labours of intellectual industry,—the quarrier of the stone, and the fine carvers thereof; the miner that digs the ore, and the smith that fashions it in the fire—for all who are employed on this sacred building, we are justly entitled to claim, that they shall BQ 22 not be forced, like the builders of another temple, to work with arms in their hands—we are bound to wish them God speed: it is our duty, our pride, and pleasure, each in our degree, to aid their efforts, and animate their zeal. Go on, and prosper, Gentlemen, amid the best wishes of the wise and good; look well on the beauty of the fabric you are adorning, and mark its substantial utility ; see piety kneeling at its altar, and human infirmities crowding to its gate. With such thoughts within, and such sympathies without, strengthen and regale yourselves amidst your toils,and remember that they carry with them a far higher reward than any human sympathy, in the approbation and the blessing of the great Father of Truth. POSTSCRIPT. I have taken notice in the foregoing address, that the éloge of Watt, delivered to the French Academy by one of its secretaries, and subjoined to the Annuaire for 1839 published under the authority of the Bureau des Longitudes, is blemished by statements which reflect unjustly on the character of one whose memory is cherished among us, as a bright example of the union of modesty with science, of the purest love of truth, with the highest faculties for its discovery, and the most eminent success in its attainment. Perceiving these statements to be founded in mistake, I took the earliest opportunity of rectifying them, at the meeting of the British Association which followed within two or three weeks after I became acquainted with them, rejoicing that I had it in my power, from the position in which I had the honour of being placed, to make the cor- rection of the error as formal and public as its promulgation had been ; and persuaded that M. Arago, as soon as he should be fully possessed of the facts, would consider it a duty which he owed both to the Aca- demy and to himself, to retract the suspicions which he had expressed. I regret, however, to find that I have not as yet succeeded in stating the case with sufficient clearness to satisfy him, and that he continues to maintain before the Academy* the correctness of his views, corro- borating them at the same time with the additional authority of M. Dumas. M. Arago says, that the account I have given of the disco- very of the composition of water is incomplete (¢rongué), and I feel it to be due to him to supply what may have been wanting in it, and to furnish him with such evidence as can no longer leave any doubt upon his mind. * Comptes rendus for January 20, 1840, p. 109, No. 3. 23 The proofs which I have already alleged, that Cavendish owed nothing either to the experiments of which Priestley sent an account to the Royal Society, on the 21st of April 1783, or to the conclusions which Watt drew from them, were these— 1. The experiments which Cavendish made in the summer of 1781 not only necessarily involved the notion (which is the claim set up for Watt), but substantially established the fact (which is the claim set up for Priestley) of the composition of water. 2. The experiment which Priestley made in April 1783, for the pro- Sessed purpose of verifying the fact of the conversion of air into water, communicated to him by Cavendish, added nothing to the proofs which Cavendish had already obtained of it nearly two years before. 3. Whilst the views of Cavendish are shown by the internal evi- dence of the experiments themselves, and the train of reasoning which they imply, to have been from the first precise and philosophical, those of Priestley and Watt were always, as regards the former, and till after the publication of Cavendish’s and Lavoisier’s papers, as regards the latter, vague and wavering to a degree scarcely comprehensible to those who have not studied the ideas prevalent at that period of chemi- cal history. These three positions I hope now to establish in a manner which will leave M. Arago nothing more to desire. The opinion of Watt has been called a theory, a doctrine, and even a hypothesis; and a northern critic *, who views this question of indi- vidual justice as one of national honour, allows the claim of Cavendish to the proof of the fact, but reserves for Scotland the eredit of the hypothesis. So far, certainly, as it involved the theories of heat and phlogiston, it was a hypothesis; but so far as it related to the conver- sion of inflammable and dephlogisticated airs into water, it was simply an opinion that Priestley had succeeded in proving the point which he, after Cavendish, had made an experiment expressly to ascertain. Whatever it be called, however, whether a statement of the result of Priestley’s experiment, or a hypothesis, or a doctrine, or a theory, it was no sooner conceived than placed by Watt on the shelf, and left there from April to November: the experiment of Priestley also remained in abeyance. Priestley has given reason enough for his not prosecuting so important an inquiry further, by informing us that it belonged to Cavendish: Watt has also assigned a reason for his sus- pense ; and I have shown in my address, that that reason proves him * Edinburgh Review, No. 142, 24 to have had no clear conception of the composition of water as consist- ing of oxygen and hydrogen: it proves that with him hydrogen and phlogiston were not convertible terms. In this I am sure MM. Arago and Dumas will agree with me, whenever they shall take the trouble to compare with attention Priestley’s paper on “the Seeming Conversion of Water into Air,” and Watt’s reference to that paper in the preface to his letter to M. de Luc. The following is his own account of his theory. “I first thought,” he says, “of this way of solving the phenomena, in endeavouring to ‘account for an experi- ment of Dr. Priestley’s wherein water appeared to be converted into air ; and I communicated my sentiments in a letter addressed to him, dated April 26, 1783, with a request that he would do me the honour to lay them before the Royal Society; but before he had an opportunity cf doing me that favour, he found, in the pro- secution of his experiments, that the apparent conversion of water into air by exposing it to heat in porous earthen vessels, was not a real transmutation, but an exchange of the elastic fluid for the liquid, in some manner not yet accounted for: therefore, as my theory was no longer applicable to the explaining these experiments, I thought proper to delay its publication, that I might examine the subject more delibe- rately.” Now, what were these experiments on the apparent conversion of water into air? We learn from Priestley’s paper, that he obtained from the distillation of water in a porous earthen retort, a constant supply of “air of the same purity as the atmosphere,” so long as there was free access of air to the outside of the retort; and, “since,” he says, “ pure external air was necessary to procure good air, it was concluded by many of my friends, and especially Mr. Watt, that the operation of the earthen retort was to transmit phlogiston from the water contained in the [moist] clay [within the retort] to the external air*, and that the water thus dephlogisticated was capable of being converted into respt- rable air by the influence of heat.” Here inflammable gas, or hydrogen, is obviously out of the question; the phlogiston of the water, which * Tn the unpublished part of his letter, Watt states his views thus :—‘‘ On considering the last and most remarkable production of air from water imbi- bed by porous earthen vessels, the only case wherein it appears almost incon- trovertibly that nothing was concerned in the production except water and heat, I think that the earth of the vessel attracts the phlogiston from the water and gradually conveys it from particle to particle until it transmits it to the external air, which it probably phlogisticates.” ‘