mw iVn U m^} "v :-.M n n '^\H mm WiU m mwM^:i'' iiiiiiiiw m I'- ^/S.(L2^^ NOTICES OK ruR PROCEEDINGS AT THE MEETINGS OF THE MEMBERS OF THB ittogal institution of ffi^reat ISritain, WITH ABSTRACTS OF THE DISCOURSES DELIVEKED AT THE EVENING MEETINGS. VOL. II. 1854 1858. LONDON: PRINTED BY WILLIAM CLOWES AND SONS, 14, CHARING CROSS. 1858. patron, HER MOST QRACIOUS MAJESTY QUEEN VICTORIA. HIS BOYAL HIGHNESS THE PRINCE CONSORT, K.G. K.C.B. D.C.L. F.R.S. &c. President. — The Duke op Northumberland, K.Gr. F.R.S. Treasurer. — William Pole, Esq. M.A. F.R.S. Vice-President. Secretary. — Rev. John Barlow, M.A. F.R.S. Vice-President. Managers. 1858-59. Lord Ashburton,D.C.L. F.R.S.- V.P. Warren De la Rue, Esq. Ph.D. F.R.S. George Dodd, Esq. F.S.A. Sir Charles Fellows, F.G.S. William Robert Grove, Esq. M.A. Q.C.F.R.8.— r.P. Sir Charles Hamilton, Bart. C.B. Sir Henry Holland, Bart. M.D. F.R.S. Henry Bence Jones, M.D. F.R.S. Sir Roderick I. Murchison, G.C.S. D.C.L. F.R.S.— V.P. James Rennie, Esq. F.R.S. Robert P. Roupell, Esq. M.A. Q.C. Rev. William Taylor, F.R.S. John Webster, M.D. F.R.S. CharlesWheatstone, Esq. F.R.S.- V.P. Col. Philip James Yorke, F.R.S. Visitors. 1858-59. Allen Alexander Bathurst, Esq. M.P. John Charles Burgoyne, Esq. John Robert F. Burnett, Esq, C. Wentworth Dilke, jun. Esq. William Gaussen, Esq. John Hall Gladstone, Esq. Ph.D. F.R.S. Thomas Lee, Esq. Charles Lyall, Esq. Thomas N. R. Morson, Esq. Sir Edwin Pearson, M.A. F.R.S. Henry Pemberton, Esq. James Rennell Rodd, Esq. William Roxburgh, M.D. Joseph Skey, M.D. John Godfrey Teed, Esq. M.A. Q.C. Honorary Professor of Chemistry- F.R.S: L. & E. &c. -William Thomas Brande, Esq. D.C.L. Fullerian Professor of Che7nistry—MiCKXE.i. Faraday, Esq. D.C.L. F.R.S. &c. Fullerian Professor of Physiology. — Richard Owen, Estj. D.C.L. F.R.S. &c. Professor of Natural Philosophy— J ona Tyndall, Esq. Ph.D. F.R.S. &c. Assistant Secretary and Keeper of the Library — Mr. B. Vincent. Clerk of Accounts and Collector — Mr. W. Hughes. Assistant in the Laboratory — Mr. Charles Anderson. CONTENTS. 1854. Page Nov. 6.— General Monthly Meeting , , . .1 Dec. 4. — General Monthly Meeting .... 5 1855. Jan. 19. — Professor Faraday — On some points of Mag- netic philosophy . , . • . 6 „ 26. — Professor Tyndall — On the Nature of the Force by which bodies are repelled from the poles of a Magnet ...... 13 Feb. 2. — G. B. Airy, Esq. — On the Pendulum Experiments lately made in the Harton Colliery, for ascertain- ing the mean Density of the Earth , . .17 „ 5. — General Monthly Meeting . . . .23 „ 9. — Professor Owen — On the Anthropoid Apes and their relations to Man . . . . ,26 „ 16. — Edward Jekyll, Esq. — On Siege Operations . 42 „ 23. — John Dickinson, Esq. — On providing an addi- tional Supply of Pure Water for London , 47 March 2.— Dr. John Stenhouse — On the Economical Appli- cations of Charcoal to Sanitary purposes • . 53 „ 5. — General Monthly Meeting • . . .55 „ 9. — Thomas Sopwith, Esq. — On the Mining Districts ofthe North of England . . . .57 „ 16.— Dr. Wm. Odling — On the Constitution of the Hydro-Carbons ...... 63 „ 23. — Rev. John Eyre Ashby— On (so called) Cata- lytic action and combustion ; and theories of Catalysis ....... 66 „ 30. — Rev. John Barlow — On the application of Che- mistry to the Preservation of Food . . 72 April 2.— General Monthly Meeting .... 80 IV CONTENTS. Page April 20.— T. H. Huxley, Esq. — On certain Zoological Arguments commonly adduced in favour of the hypothesis of the Progressive Development of Animal Life in Time . . . . 82 „ 27. — Sir Charles Lyell — On certain trains of Erratic Blocks on Western borders of Massachusetts, U.S. 86 May 1. — Annual Meeting ...... 98 „ 4. — Dr. J. H. Gladstone— On Gunpowder and its substitutes ...... 99 „ 7. — General Monthly Meeting .... 104 „ 11. — Henry Bradbury, Esq. — On Nature-Printing . 106 „ 18. — James Philip Lacaita, Esq.— On Dante and the Divina Commedia . . . .118 „ 25. — Professor Faraday — On Electric Conduction . 123 June 1. — Professor Tyndall — On the Currents of the Leyden Battery . , , ... 132 „ 4. — General Monthly Meeting . . . .136 „ 8. — Professor Faraday — On RuhmkorfTs Induction Apparatus . , . . . .139 „ 15. — Col. H. C. Rawlinson — On the Results of the Excavations in Assyria and Babylonia . . 1 43 July 2. — General Monthly Meeting . , . .145 Nov. 5. — General Monthly Meeting . , . .147 Dec. 3.— General Monthly Meeting . . . .150 1856. Jan. 25. — W. R. Grove, Esq. — Inferences from the Nega- tion of Perpetual Motion . . . .152 Feb. 1. — Professor Tyndall — On the Disposition of Force in Paramagnetic and Diamagnetic Bodies 1 59 „ 4. — General Monthly Meeting . . . .164 „ 8. — Professor Henry D. Rogers — On the Geology and Physical Geography of North America . 167 „ 15. — Professor T. H. Huxley — On Natural History as Knowledge, Discipline, and Power . .187 „ 22. — Professor Faraday — On certain Magnetic Actions and Affections • . • .196 CONTENTS. T Page Feb. 29.— Phofessou Wm. Thomson— On the Origin and Transformations of Motive Power . .199 March 3.— General Monthly Meeting .... 205 „ 7. — Sir Charles Lyell — On the Successive Changes of the Temple of Serapis . . . .207 „ 14. — Rev. John Barlow — On Aluminium . . 215 April 4. — Henry E. Roscoe, Esq. — On the Measurement of the Chemical Action of Light . . . 223 „ 7. — General Monthly Meeting .... 225 „ 11. — C. W. Siemens, Esq.— On a Regenerative Steam- Engipe 227 „ 18. — Dr. H. Bence Jones — On Ventilation, and the means of determining its amount . . . 236 „ 21. — Dr. Humphry Sandwith — On the Siege of Kars 246 „ 25. — W. B. Donne, Esq. — On the works of Chaucer, considered as Historical Illustrations of England in the 14th century ..... 248 May 1. — Annual Meeting ...... 254 „ 2. — Professor Owen — On the Ruminant Quadrupeds and the Aboriginal Cattle of Britain . . 256 „ 5. — General Monthly Meeting .... 261 „ 9. — Henry Bradbury, Esq. — On the Security and Manufacture of Bank Notes . . . 263 „ 16. — Dr. a. W. Hofmann — On the Chemical Type Ammonia ...... 274 „ 23. — F. A. Abel, Esq. — On some of the Applications of Chemistry to Military purposes . . 283 „ 30. — Dr. Lyon Playfaib — On th€ Chemical Prin- ciples involved in Agricultural Experiments , 289 June 2. — General Monthly Meeting .... 293 „ 6. — Professor Tyndall — Comparative view of the Cleavage of Crystals and Slate Rocks . . 295 June 13. — Professor Faraday — On M. Petitjean's process for Silvering Glass : and some Observations on Divided Gold 308 July 7. — General Monthly Meeting . . . .313 Nov. 3.— General Monthly Meeting .... 315 Dec. 1. — General Monthly Meeting . . , .318 VI CONTENTS. 1857. Page Jan. 23. — Professor Tyndall — Observations on Glaciers 320 „ 30. — Rev. Frederic D. Maurice — Milton considered as a Schoolmaster ..... 328 Feb. 2. — General Monthly Meeting .... 333 „ 6. — Dr. J. H. Gladstone — On Chromatic Phaeno- mena exhibited by Transmitted Light . . 336 „ 13. — T. A. Malone, Esq. — On the application of Light and Electricity to the production of En- gravings— Photogalvanography . . , 343 „ 20. — Christopher Dresser, Esq. — On the Relation of Science and Ornamental Art . . . 350 „ 27. — Prof. Faraday — On the Conservation of Force 352 March 2. — General Monthly Meeting .... 366 „ 6. — Edmund Beckett Denison, Esq. — On the Great Bell of Westminster 368 „ 13. — Professor John Phillips— On the Malvern Hills 385 „ 20. — John Watkins Brett, Esq. — On the Submarine Telegraph 394 „ 27. — Robert Warington, Esq. — On the Aquarium 403 April 3.— Rev. John Barlow — On some Modifications of Woody Fibre, and their Applications . . 409 „ 6.—General Monthly Meeting .... 413 „ 24. — Professor A. C. Ramsay — On certain Peculi- arities of Climate during part of the Permian Epoch 417 May 1. — Annual Meeting . . , . , .421 „ 1. — Captain John Grant — On the Application of Heat to Domestic Purposes, and to Military Cookery 422 „ 4. — General Monthly Meeting .... 426 „ 8. — Professor F. Grace Calvert — On M. Chev- reul's Laws of Colours .... 428 „ 15. — Professor T. H. Huxley — ^^On the present state of Knowledge as to the Structure and Functions of Nerve 432 CONTENTS. Vll Page May 22. — Edward Vivian, Esq. — On Meteorology, with Observations and Sketches taken during a Bal- loon Ascent ...... 437 „ 29. — Professor A. J. Scott— Physics and Metaphy- sics. (No Abstract) 439 June 1. — General Monthly Meeting .... 439 „ 5. — Professor Tyndall — On M. Lissajous* Acous- tic Experiments . , . , .441 , 12. — Professor Faraday — On the relations of Gold to Light 444 July 6. — General Monthly Meeting .... 446 Nov. 2. — General Monthly Meeting .... 449 Dec, 7. — General Monthly Meeting .... 452 1858. Jan. 22. — Professor Tyndaul — On some Physical Proper- ties of Ice . , . . . . 454 „ 29. — W. R. Grove Esq. — On Molecular Impressions by Light and Electricity . . . .458 Feb. 1. — General Monthly Meeting .... 464 „ 5. — Dr. Edwin Lankester — On the Drinking Waters of the Metropolis ..... 466 „ 12. — Professor Faraday — On Static Induction 470, 490 „ 19. — Edmund Beckett Denison, Esq. — On some of the Improvements in Locks since the Great Ex- hibition of 1851 475 „ 26. — Professor Baden Powell — On Rotatory Sta- bility and its Applications to Astronomical Ob- servations on board Ships . • • . 480 March 1 . — G eneral Monthly Meeting .... 488 „ 5. — Professor C. Piazzi Smyth — Account of the Astronomical Experiment of 1856 on the Peak ofTeneriffe 493 „ 12. — Dr. William B. Carpenter — On the Lowest (Rhizopod) Type of Animal Life, considered in its relations to Physiology, Zoology, and Geology 497 Vlll CONTENTS. Page Mar. 19. — Henry Thomas Buckle, Esq.— On the Influence of Women on the Progress of Knowledge . 504 „ 26. — Eev. John Barlow — On Mineral Candles and other Products manufactured at Belmont and Sherwood 506 April 5. — General Monthly Meeting .... 509 „ 16. — Robert Godwin- Austen, Esq. — On the Condi- tions which determine the probability of Coal beneath the South-Eastern parts of England . 511 „ 23. — Col. Henry James — On the Geodetic Opera- tions of the Ordnance Survey . . .516 „ 30.— Professor A. C. Ramsay — On the Geological Causes that hate influenced the Scenery of Canada and the North-Eastern Provinces of the United States 522 May 1, — Annual Meeting ...... 524 „ 3. — General Monthly Meeting .... 526 „ 7. — James Philip Lacaita, Esq. — On the late Earth- quakes in Southern Italy .... 528 „ 14. — Henry Bradbury, Esq. — Printing: its Dawn, Day, and Destiny. {No Abstract) . . 534 „ 21. — Professor T. H. Huxley — On the Phenomena of Gemmation ...... 534 „ 28. — Professor Edward Frankland — On the pro- duction of Organic Bodies without the agency of Vitality 538 June 4. — Professor Tyndall — On the Mer-de-Glace . 544 „ 7. — General Monthly Meeting .... 554 „ 11. — Professor Faraday — On Wheatstone's Electric Telegraph, in Relation to Science . . . 555 July 5. — General Monthly Meeting .... 560 Index . . t ..... . 562 iSogal ingtittttion of iJKreat Uritain, 1854. GENERAL MONTHLY MEETING, Monday, November 6. Professor C. Wheatstone, F.R.S. Vice-President, in the Chair. The following Report was read : — " Royal Institution, November 6, 1854. " The Managers Report, — That the Fullerian Professorship of Physiology is now vacant; and that, pursuant to the Deed of Endowment, the election of a Professor will take place on Monday, the 2nd of July, 1855, at 4 o'clock, p.m. " They further Report, — That the next Actonian Prize of £105 will be awarded in the year 1858, to an Essay illustrative of the Wisdom and Beneficence of the Almighty as manifested by the Influence of Solar Radiation. — Competitors for this prize are re- quested to send their Essays to the Royal Institution, on or before 10 o'clock, P.M., December 31st, 1857, addressed to the Secretary. The adjudication will be made on Monday, April 12th, 1858." The following Presents were announced, and the thanks of the Members returned for the same : — From Her Majesty's Government {by Sir H. De la JBecAe)— Memoirs of the Geologi- cal Survey of the United Kingdom: British Organic Remains, Decades 4, 6, and 7. 4to. 1852-3. Records of the School of Mines, Vol. I. Parts 2, 3, 4. 8vo. 1853. Actuaries, Institute of— The Assurance Magazine, Nos. 16, 17. 8vo. 1854. Agricultural Society of England, lioyal — Journal, Vol. XV. Parti. 8vo. 1854. Airy, O. B. Esq. Astronomer- Roy al—DescYi^Wan of the Transit Circle at the Royal Observatory, Greenwich. 4to. 1854. American Academy of Arts and Sciences — Proceedings, Vol. II. Nos. 21-29. Vol. III. Nos. 1-13. 8vo. 1849-54. American Philosophical Sbc/efy— Proceedings, Nos. 49, 50. 8vo. 1853-4. Amsterdam, Koninklijke Akademie van Wetensc happen — Verhandelingen, Eerste Deel. 4to. 1854. Verslagen en Mededeelungen, Eerste Deel ; en Tweede Deel, Eerste en Tweede Stuk. 8vo. 1853-4. Arnold, Thos. J. Esq. (the ^wfAor)— Treatise on the Law relating to Municipal Corporations. 1 2mo. 1851. Vol. II.— (No. 20.) B 2 General Monthly Meeting, [Nov. 6, Asiatic Socicti/ of Benqnl -Journal, Nos. 240, 241. 8vo. 1854. Asiatic Society, 7?oi/tf/— Journal, Vol. XVI. Part 1. Svo, 1854. Catalogue of Ai-abic*and Persian MSS. in the Society's Library. By W. H. Morley. 8vo, 1854. Astronomical Society, Roi/al — Memoirs, Vol. XXII. 4to. 1854. Monthly Notices, Vol. XIII. Vol. XIV. Nos. 8, 9. 8vo. 1853-4. Author — A Catechism explanatory of many of the commonly supposed Difficul- ties of Christianity. 12mo. 1854. Basel, Naturforschende Gesellschaji — Berichte iiber die Verhandlungen, I-VIII. Svo. 1835-49, Verhandlungen, Heft I. 8vo. 1854* Bell, Jacob, Esq. M.E.I. — Pharmaceutical Journal, August to November, 1854. Svo. Biber, Rev. G. E. LL.D. M.R.r.»(the Author)— lAterature, Art, and Science, considered as a means of elevating the Popular Mind. (A Lecture.) Svo. 1854. Bombay Geographical -Socief^— Transactions, Vol. XI. Svo. 1854. Boosey, Messrs. {the Publishers) — The Musical World for July to Oct. 1854, 4to. Boston Society of Natural History— Journal, Vol. VI. No. 3. Svo. 1853. Proceedings, Nos. 15-24. Svo. 1852-4. Bolfield, B. Esq. F.R.S. M.R.L (the Author)— Eemarks on the Prefaces to the Fii-st Editions of the Classics. Svo. 1 854. British Architects, Royal Institute o/^— Proceedings in July, 1854. 4to. British Association — Report of the Twenty-third Meeting, held at Hull in 1853. Svo. 1854. Brown, Andrew, Esq. (the Author) — The Philosophy of Physics, or Process of Creative Developement. Svo. New York, 1854. Chemical Society — Quarterly Journal, Vol. VII. Nos. 2, 3. Svo. 1854. Commissioners in Lunacy — Eighth Report to the Lord Chancellor. Svo. 1854. Cornwall Polytechnic Society, Royal — Twenty-first Annual Report. Svo. 1853. Decimal Association — Proceedings, with an Introduction by Professor De Morgan. Svo. 1854. East India Company, the Hon. — Gazetteer of the Territories under the Govern- ment of the East India Company, and of the Native States on the Continent of India. By E. Thornton. 4 vols. Svo. 1854. Editors — The Medical Circular, for July to October, 1854, Svo. The Athenaeum, for July to October, 1854. 4to. The Practical Mechanic's Journal, for July to October, 1854. 4to. The Mechanics' Magazine, for July to October, 1854. Svo. The Journal of Gas-Lighting, for July to October, 1854. 4to. Deutsches Athenaum, July to October, 1854. 4to. Ethnological Society of London — Address by Sir B. C. Brodie, Bart followed by a Sketch of the recent Progress of Ethnology, by R. Cull. Svo. 1854, Faraday, Professor, D.C.L. F.R.S. — Monatsbericht der Konigl. Preuss. Akademie, Mai zu August, 1 854. Svo. Berlin. Abhandlungen der Koniglichen Akademie der Wissenschaften zu Berlin, 1853. 4to. 18.54. Kaiserliche Akademie der Wissenschaften, Wien : — Philosophisch- Historische Classe : — Sitzungsberichte, Band XL Hefte 4, 5 ; Band XII. Hefte 1-4; und Register zu Band I-X. Svo. 1854. Denkschriften. Band V. 4to. 1854. Archiv fiir Kunde CEsterreichischer Geschichts Quellen. Band XII. Svo. 1854. Notizenblatt. (Beilagezum Archiv.) 1853. Nos. 21-24; 1854. Nos. 1-17. Pontes Rerum Austriacarum. Zweite Abtheilung. Band I. 1854. Mathematisch-JSaturwissenschaftliche Classe: — Denkschriften. Baud VII. 4to. 1854. Sitzungsberichte. Band XL Heft 5 ; Baud XII. Hefte 1-4. Svo. 1S53-4. Tafeln der Polygraphische Apparat. Von A. Auer. Svo. 1853. 1854.] General Monthly Meeting, 8 Faraday, Professor, D.C.L. F.R.S. — Bulletin de la Classe Physico-MathcJ- matlque de 1' Academic Imperiale des Sciences de ^t. Pe'tersbourg. Tome XII. 4to. 1854. L' Academic Roy ale de la Belgique : — Annuaire. 1854. 8vo. Bulletins des Stances de la Classe des Sciences, Ann^e 1853. 8vo. Me'moires pre'sente's par divers Savans a 1' Academic des Sciences de I'lnstitut Imperial de France ; Sciences Math^matiques et Physiques. Tome XII. 4to. Paris, 1854. Franklin Institute cf Pennsylvania— J ouTDail, Vol. XXVII. No. 6. Vol. XXVIII. No. 1-3. 8vo. 1854. Geneve, Socie't(f de Physique rfe— M6moires, Tome XIII. 2me Partie. 4to. 1854. Geographical Society^ Royal— Address by the Earl of Ellesmere, May 1864. 8vo. Geological Society — Quarterly Journal, No. 39. 8vo. 1854. Graham, George, Esq. Registrar- General — Census of Great Britain, 1851 : Population Tables: Ages, Condition, &c., Report and Summary Tables. fol. 1854. Weekly Reports of the Registrar-General for July to October, 1854. 8vo. Graham, £t.- Colonel J. D. U.S. {the Author) — Report on the Boundary Line between the United States and Mexico. (Maps.) 8vo. 1853. Greenwich Royal Observatory — Astronomical and Magnetical and Meteorologi- cal Observations in 1852. 4to. 1854. Guggenbiihl, Dr. — Die Cretinen : Heilanstalt auf dem Abendberg in der Schweiz. Von Dr. Guggenbiihl. 4to. Bern, 1853. Una Visita all' Abendberg, 10 Settembre, 1850, del Medico Sella Alessan- dro. 8vo. Cretins and Idiots — A Short Account of the Progress of the Institutions for their relief and cure. 8vo. 1853. Horticultural Society of Lo7ido7i—Jo\xni2il,Yol. IX. No. 3. 8vo. 1854. Huxley, Thomas H. F.R.S. {the Author)— On the Educational Value of the Natural History Sciences. 8vo. 1854. Literary Fund, Royal — Report for 1854. 8vo. Londesborough, Lord, K.CH. M.RJ. — Miscellanea Graphica : a collection of Ancient, Mediaeval, and Renaissance Remains in the possession of Lord Londesborough. Part 2. 4to. 1854. Lovell, E. B. Esq. M.R.L {the Editor)— The Monthly Digest, for July to October, 1854. 8vo. The Common Law and Equity Reports. Parts 15-21. 8vo. 1854. Lubbock^ John, Esq. M.R.L— On some Arctic Species of Calanidae. 8vo. 1854, Lyell, Sir Charles, F.R.S. {the Author)— Sjpeciol Report on the Geological, Topographical, and Hydrographical Departments of the New York In- dustrial Exhibition for 1854. fol. 1854. Melloni, Mac€doine, F.R.S. Hon. M.R.I, {the Author)— ha. Thermochrose, ou la Coloration Calorifique. Premiere Partie. 8vo. Naples, 1850. Mure, Col. William, M.P. F.S.A. {the Editor)— Selections from the Family Papers preserved at Caldwell : 1496-1853. 3 vols. 4to. 1854. Murchison, Sir R. I. D.C.L. F.R.S. M.R.L {the Author)— Silnndi. The History of the Oldest known Rocks containing Organic Remains. 8vo. 1854. North of England Institute of Mining Engineers — Transactions, Vol. I. 8vo, 1852-3. Norton, Mr. C. B. (the Publisher)— Norton's Literary Register, 1854. 16mo. New York. Novello, Mr. {the Publisher)— The Musical Times, for July to October, 1854. 4to. Photographic Society— J onm&\, Nos. 20-23. 8vo. 1854. b2 4 General Monthly Meeting. [Nov. 6j Quetelety M. Hon. M.R.T. (the Author)— Sur le Climat de la Belgique: De rHygrometrie. 4to. Bruxelles, 1854. Sur I'Electricite des Nuages orageux. 8vo. Phenomenes Periodiques. 16mo. 1852. Beid, P. Sandeman, Esq. — Letter on the Ventilation of Collieries. By John Buddie. 8vo. 1814. Eot/al Society, ZonJon— Philosophical Transactions, Vol. CXLIV, Part 1. 4to. 1854. Proceedings, Vol. VII. No. 4-6. Svo. 1854. Sahine, Col. E. R.A. V.P.R.S. (the Author)'-On some of the Results obtained at the British Colonial Magnetic Observatories. 8vo. 1854. Smith, Mr. J. Russell (the Publisher)— The Retrospective Review. Nos. 7, 8. 1854. Smithsonian Institution, Washington — Smithsonian Contributions to Knowledge. Vol. VI. 4to. 1854. Seventh Annual Report. Svo. 1853. Annular Eclipse of May 26, 1854. 8vo. 1854. Societa delle Scienze Biologiche in Torino — Memorie, Vol. I. Fascicolo 1 . Svo. 1854. Society ojT ^rfs— Journal for July to October, 1854. Svo. Statistical Sbcteiy— Journal, Vol. XVII. Part 3. Svo. 1854. Stephens, Henry, Esq. (the Author) — Cholera : an Analysis of its Character. 12mo. 1854. Taylor, Rev. W. F.R.S. M".^./.— Magazine for the Blind, August to Novem- ber, 1854. 4to. Von der Schlaflosigkeit, deren Ursachen und Heilart. Von Dr. A. F. Fischer. 16mo. Numberg, 1831. Van Diemen's Land, Royal Society o/"— Papers and Proceedings. Vol. II. Part 2. Svo. 1854. Vereins zur Beforderung des Gewerbfleisses in Preussen — Verhandlungen, Mai zu August, 1854. 4to. Berlin. Warburton, Henry, Esq. M.A. F.R.S. M.R.I, (the Author)— On. Self-repeating Series. 4to. 1854. Washington National Observatory — Astronomical Observations made during 1847. 4to. 1853. Webster, John, M.D. F.R.S. M.R. I.— General Reports of the Royal Hospitals of Bridewell and Bethlem, and of the House of Occupations. Svo. 1853. Williams, C. W. Esq. (the Author) — The Combustion of Coal and the Preven- tion of Smoke chemically and practically considered. Svo. 1854. Yates, James, Esq. M.A. F.R.S. M.R.I. — On the French System of Measures, Weights, and Coins ; by James Yates, Esq. F.R.S. With an Abstract of the Discussion on the Paper, at the Society of Arts. Svo. 1854. Comparative Statement of Different Plans of Decimal Accounts and Coinage. By Th. W. Rathbone. Svo, 1854. Decimal Coinage — A Practical Analysis with Tables. By James Laurie. Svo. 1854. Yorkshire Geological and Polytechnic Society — Proceedings, 1853. Svo. 1854. 1854.] General Monthly Meeting, 5 GENERAL MONTHLY MEETING, Monday, December 4. William Robert Grove, Esq. Q.C. F.R.S. Vice-President, in the Chair. The Earl of Rosse, Benedict Laurence Chapman, Esq. and Henry Femberton, Esq. were duly elected Members of the Royal Institution. The Secretary reported that the following Arrangements had been made for the Lectures before Easter, 1 855 : — Six Lectures on the Chemistry of Combustion (adapted to a Juvenile Auditory), by Michael Faraday, Esq. D.C.L. F.R.S. FuUerian Professor of Chemistry, R.I. Eleven Lectures on Magnetism and Frictional Electricity, by John Tyndall, Esq. F.R.S. Professor of Natural Philosophy in the Royal Institution. Eleven Lectures on English Literature, by William B. Donne, Esq. Eleven Lectures on the Principles of Chemistry, by John Hall Gladstone, Ph.D. F.R.S. The following Presents were announced, and the thanks of the Members returned for the same : — From Bell, Jacob, Esq. M.R.I.— The Pharmaceutical Journal, for November and December. 8vo. 1854. Board of Trade — Report on the Bavarian Educational Institutions for Practical Science and Art. By J. Ward, Esq. fol. 1854. Boosey, Messrs. (the Publishers) — The Musical World for November, 1854. British Architects, Royal Institute of — Proceedings in November, 1854. 4to. Civil Engineers, Institution o/— Proceedings in November, 1854. 8vo. East India Company, the Hon. — Catalogue of the Birds in the Museum of the Hon. East India Company. By Dr. Horsfield. Vol. I. 8vo. 1854. Editors — The Medical Circular for November, 1854. 8vo. The Athenajum for November, 1854. 4to. The Practical Mechanic's Journal for November, 1854. 4to. The Journal of Gas-Lighting, November, 1854. 4to. The Mechanics' Magazine for November, 1854. 8vo. Franklin Institute of Pennsylvania— 3 ovLToal, Vol. XXVIII. No. 4. 1854. Geological Society— Quarterly Journal, No. 40. 8vo. 1854. Graham, George, Esq. ( Registrar- General) — Weekly Reports of the Registrar- General for November, 1854. 8vo. 6 General Monthly Meeting. [Dec. 4, 1854. Jopling, R. F. Esq. {the Editor)— The Statist, No. 1. 8vo. 1854. Medical and Chirurgical Society^ Royal — Medico-Chirurgical Transactions, Vol. XXXVII. Svo. 1854. Nocello, Mr. {the Publisher) — The Musical Times for November and Decem- ber, 1854. riwtographic Sbciefy— Journal, No. 24. 8vo. 1854. Pollock^ Frederick, Esq. M.A. M.R.I.— YjgXqvi OT^ViSCMldi. 3 vols. 4to. Bero- lini, 1746-51. Pollock, Thomas, Esq. (the Author) — On the peculiar State of the Atmosphere during the late Epidemic Cholera and Diarrhoea. 8vo, 1854. Price, Rev. Bartholomew, M.A. F.R.S. {the Author) — A Treatise on the Infini- tesimal Calculus. Vol. II. 8vo. 1854. Rathbone, Th. W. Esq. {the Author)— VrefdiCe to the Comparative Statement on Decimal Accounts and Coinage. 8vo. 1854. Society o/ ^r^s— Journal for November, 1854. Svo. Statistical Society— iovLva&l, Vol. XVII. Part 4. Svo. 1854. Taylor, Alfred S. M.D. F.R.S. M.R.I, {the Author)— Medical Jurisprudence. 5th Edition. 16mo. 1854. Taylor, Rev. W. F.R.S. M.R.L— The Magazine for the Blind, December, 1854. Wilhelm Von Humboldt — Lichtstrahlen aus seinen Brie fen : mit einer Bio- graphic Humboldts, von Elisa Maier. 16mo. Leipzig, 1852. Ueber das Sehen und die Farben, eine Abhandlung von A. Schopenhauer. Svo. Leipzig, 1816. Vereins zur Befordenmg des Gewf.rbfleisses in Preussen — Verhandlungen, September und October, 1854. 4to. 1855. WEEKLY EVENING MEETING, Friday, January 19. William Robert Grove, Esq. Q.C. F.R.S. Vice-President, in the Chair. Professor Faraday, D.C.L. F.R.S. On some points of Magnetic Philosophy. The magnetic and electric forms of power, being dual in their character, and also able to act at a distance, will probably aid greatly in the development of the nature of physical force generally : and if (as I believe) the dualities are essential to the forces, are always equal and equivalent to each other, and are so mutually dependent, that one cannot appear, or even exist, without the other, the proof of the truth of such conditions would lead to many consequences of the highest importance to the philosophy of force generally. A few brief experiments with the electric power quickly place the dual Jan. 19, 1855.] Prof. Faraday on Magnetic Philosophy. 7 cases before the contemplative mind. Thus, if a metallic vessel, as an ice-pail, be insulated and connected with a delicate gold leaf electrometer, or other like instrument, and then an insulated metallic globe, half the diameter of the ice-pail, be charged with positive electricity and placed in the middle of the pail, the latter being for the moment uninsulated by a touch outside, and then left insulated again, the whole system will show no signs of electri- city externally, nor will the electrometer be affected : but a carrier applied to the ball within the vessel will bring away from it positive electricity, showing its particular state of charge ; or being applied to the lower inside surface of the vessel will bring away negative electricity, proving that it has the contrary state : or the duality may be proved by withdrawing the ball, when the vessel will show itself negative by the electrometer, and the ball will be found positive. That these dualities are equal, is further shown by replac- ing the ball within the vessel, observing the electrometer, bringing tlie ball and vessel in contact, and again observing the electrometer, which will remain unchanged ; and finally withdrawing the ball, which comes away perfectly discharged, and leaves the vessel exter- nally in its unchanged and previous state. So the electric dualities are equal, equivalent, and mutually sustained. To show that one cannot exist alone, insulate the metallic vessel, charge it strongly by contact with the machine or a Leyden jar, and then dip the insulated ball into it ; and after touching the bottom of the vessel with the ball, remove it, without touching the sides : it will be found absolutely free from charge, whatever its previous state may have been ; for none but a single state can exist at the bottom of such a metallic vessel ; and a single state, i.e. an unrelated duality, cannot exist alone. The correspondent dualities, i.e. the northness and the southness, of the magnetic force are well known. For the purpose of insulat- ing, if possible, one of these, and separating it in any degree from the other, numerous experiments have been made. Thus six equal electro-magnets, formed of square bars, were put together in the direction of three lines perpendicular to each other, so that their inner ends, being all alike in polarity, might inclose a cubical space and produce an experimental chamber. When excited, these magnets were very powerful in the outer direction, as was found by nails, filings, spirals, and needles ; but within the chamber, walled in on every side by intense north poles, there was no power of any kind : filings were not arranged ; small needles not affected, except as they by their own inducing powers caused arrangement of the force within ; revolving wire helices produced no currents ; the chamber was a place of no magnetic action. Ordinary magnetic poles of like nature produced corresponding results. A single pole presented its usual character, attracting iron, repelling bismuth ; a like pole, at right angles to it, formed a re-entering angle, and there a weak place of magnetic action was caused ; ifon was attracted from 8 Professor Faraday [Jan. 19, it to the prominent corners ; bismuth moved up into it ; and a third like pole on the opposite side made the place of weak force still weaker and larger ; another pole or two made it very weak ; six poles brought it to the condition above described. Even four poles, put with their longer edges together, produced a lengthened chamber with two entrances ; and a little needle being carried in at either entrance passed rapidly through spaces of weaker and weaker force, and found a part in the middle where magnetic action was not sensible. Other very interesting results were obtained by making chambers in the polar extremities of electro-magnets. A cylinder magnet, whose core was 1 * 5 inches in diameter, had a concentric cylindrical chamber formed in the end, 0*7 in diameter, and 1"3 inches deep. When iron filings were brought near this excited pole, they clung around the outside, but none entered the cavity, except a very few near the outer edge. When they were purposely placed inside on a card they were quite indifferent to the excited pole, except that those near the mouth of the chamber moved out and were attracted to the outer edges. A piece of soft iron at the end of a copper wire was strongly attracted by the outer parts of the pole, but unaffected within. When the chamber was filled with iron filings and inverted, the magnet being excited, all those from the bottom and interior of the chamber fell out ; many, however, being caught up by the outer parts of the pole. If pieces of iron, successively increasing from the size of a filing to a nail, a spike, and so on to a long bar, were brought into contact with the same point at the bottom of the inverted chamber, though the filing could not be held by attraction, nor the smaller pieces of iron, yet as soon as those were employed which reached to the level of the chamber mouth, or beyond it, attraction manifested itself; and with the larger pieces it rose so high that a bar of some pounds weight could be held against the very spot that was not sufficient to retain an iron filing. These and many other results piove experimentally, that the magnetic dualities cannot appear alone ; and that when they are developed they are in equal proportions and essentially connected. For if not essentially connected, how could a magnet exist alone ? Its power, evident when other magnets, or iron, or bismuth is near it, must, upon their removal, then take up some other form, or exist without action: the first has never been shown or even suspected ; the second is an impossibility, being inconsistent with the conserva- tion of force. But if the dualities of a single magnet are thrown upon each other, and so become mutually related, is that in right lines through the magnet, or in curved lines through the space around ? That it is not in right lines through the magnet (it being a straight bar or sphere) is shown by this, that the proper means as a helix round the magnet, shows that the internal disposition of the force (coercitive or other) is not affected when the magnet is exert- 1855.] on Magnetic Philosophy. 9 ing its power on other magnets, or when left to itself {Experimental Researches, 3119, 3121, 3215, &c.) ; and like means show that the external disposition of the force is so affected : so that the force in right lines through the magnet does not change under the circumstances, whilst the force in external (and necessarily) curved lines does. The polarity of bismuth or phosphorus in the magnetic field is one point amongst many others essentially dependent upon, and highly illustrative of the nature of, the magnetic force. The as- sumption that they have a polarity the reverse of that of para- magnetic bodies involves the consequence, that northness does not always repel northness or attract southness ; or else leads to the assumption that there are two northnesses and two southnesses, and that these sometimes associate in pairs one way, and at other times in the contrary way. But leaving the assumptions and reverting to experiment, it was hoped that a forcible imitation of the imagined state of bismuth in the magnetic field, might illustrate its real state, and, for this purpose, recourse was had to the indica- tions given by a moving conductor. Four spheres of copper, iron, bismuth, and hard steel have been prepared, and rotated upon an axis coincident with the magnetic axis of a powerful horse-shoe magnet ; each sphere has a ring of copper fixed on it as an equator, and the ends of a galvanometer wire were brought into contact with the axis and the equator of the revolving globe. Under these circumstances, the electric current produced in the moving globe was conveyed to the galvanometer, and became the indicator of the magnetic polarity of the spheres ; the direction of rotation, and the poles of the magnet, being in all cases the same. When the copper sphere, as a standard, was revolved, deflection at the galvanometer occurred in a certain direction. When the iron sphere replaced the copper and was revolved, the deflection at the galvanometer was the same. When the bismuth sphere was employed, the de- flection was still the same : — and it still remained the same when the steel sphere was rotated in the magnetic field. Hence, by this effect, which I believe to be a truthful and unvarying indication of polarity, the state of all the spheres was the same, and therefore the polarity of the magnetic force in the iron, copper, and bismuth, in every case alike. {Exp. Res. 3164, &c.) The steel sphere was then magnetized in the direction of its axis, and was Tound to be so hard as to retain its own magnetic state when in a reverse direction between the poles of the dominant magnet, for upon its removal its magnetism remained unchanged. Experiments were then made in a selected position, where the dominant magnetic force was not too strong — (a magnet able to lift 430 lbs. was used) — and it was found that when the steel magnet was placed in ac- cordance, i.e. with its north pole opposite the south pole of the dominant magnet, the deflection was in the same direction as with the bismuth sphere ; but when it was changed so as to be in 10 Professor Faraday [Jan. 19, the magnetic condition assigned by some to bismuth {i.e. with reversed pohirities), it then differed from bismuth, producing the contrary deflection. [For a further account of these considerations and investigations, a paper may be referred to, which will appear in the February number of the Philosophical Magazine.] It is, pro))ably, of great importance that our thoughts should be stirred up at this time to a reconsideration of the general nature of physical force, and especially to those forms of it which are con- cerned in actions at a distance. These are, by the dual powers, connected very intimately with those which occur at insensible distances ; and it is to be expected that the progress which physi- cal science has made in latter limes will enable us to ap- proach this deep and difficult subject with flxr m.ore advantage than any possessed by philosophers at former periods. At present we are accustomed to admit action at sensible distances, as of one magnet upon another, or of the sun upon the earth, as if such admission were itself a perfect answer to any enquiry into the nature of the physical means which cause distant bodies to affect each other ; and the man who hesitates to admit the sufficiency of the answer, or of the assumption on which it rests, and asks for a more satisfactory account, runs some risk of appearing ridiculous or ignorant before the world of science. Yet Newton, who did more than any other man in demonstrating the law of action of distant bodies, including amongst such the sun and Saturn, which are 900 millions of miles apart, did not leave the subject without recording his well-considered judgment, that the mere attraction of distant portions of matter was not a sufficient or satisfactory thought for a philosopher. That gravity should be innate, inherent, and essential to matter, so that one body may act upon another at a distance through a vacuum, without the mediation of anything else, by and through which their action and force may be conveyed from one to another, is, he says, to him a great absurdity. Gravity must be caused by an agent, acting constantly according to certain laws ; but whether this agent be material or immaterial he leaves to the consideration of his readers. This is the onward looking thought of one, who by his knowledge and like quality of mind, saw in the diamond an unctuous substance coagulated, when as yet it was known but as a transparent stone, and foretold the presence of a combustible substance in water a century before water was decomposed or hydrogen discovered : and I cannot help believing that the time is near at hand, when his thought regarding gravity will produce fruit : — and, with that impression, I shall venture a few considerations upon what appears to me the insufficiency of the usually accepted notions of gravity, and of those forces generally, which are supposed to act at a distance, having respect to the modern and philosophic view of the conservation and indestructi- bility of force. The notion of the gravitating force is, with those who admit 1855.] on Gravity. 11 Newton's law, but go with him no further, that matter attracts matter with a strength whicJi is inversely as the square of the distance. Consider, then, a mass of matter (or a particle), for which present purpose the sun will serve, and consider a globe like one of the planets, as our earth, either created or taken from distant space and placed near the sun as our earth is ; — the attraction of gravity is then exerted, and we say that the sun attracts the earth, and, also, that the earth attracts the sun. But if the sun attracts the earth, that force of attraction must either arise because of the presence of the earth near the sun ; or it must have pre-existed in the sun when the earth was not there. If we consider the first case, I think it will be exceedingly difficult to conceive that the sudden presence of an earth, 95 millions of miles from the sun, and having no previous physical connexion with it, nor any physical connexion caused by the mere circumstance of juxtaposition, should be able to raise up in the sun a power having no previous existence. As respects gravity, the earth must be considered as inert, pre- viously, as the sun ; and can have no more inducing or affecting power over the sun than the sun over it : both are assumed to be without power in the beginning of the case ; — how then can that power arise by their mere approximation or co-existence ? That a body without force should raise up force in a body at a distance from it, is too hard to imagine ; but it is harder still, if that can be possible, to accept the idea when we consider that it includes the creation ofjorce. Force may be opposed by force, may be diverted, directed partially or exclusively, may even be converted, as far as we understand the matter, disappearing in one form to reappear in another ; but it cannot be created or annihilated, or truly suspend- ed, i.e. rendered existent without action or without its equivalent action. The conservation of power is now a thought deeply im- pressed upon the minds of philosophic men ; and I think that, as a body, they admit that the creation or annihilation of force is equally impossible with the creation or annihilation of matter. But if we conceive the sun existing alone in space, exerting no force of gravitation exterior to it ; and then conceive another sphere in space having like conditions, and that the two are brought towards each other ; if we assume, that by their mutual presence each causes the other to act, — this is to assume not merely a creation of power but a double creation, for both are supposed to rise from a previously inert to a powerful state. On their dissociation they, by the assumption, pass into the powerless slate again, and this would be equivalent to the annihilation of force. It will be easily understood, that the case of the sun or the earth, or of any one of two or more acting bodies, is reciprocal ; — and also that the varia- tion of attraction, with any degree of approach or separation of the bodies, involves the same result of creation or annihilation of power as the creation or annihilation (which latter is only the total removal) of either of the acting bodies would do. 12 Prof. Faraday on Gravity. [Jan. 19, Such, I think, must be the character of the conclusion, if it be supposed that the attraction of the sun upon the earth arises because of the presence of the earth, and the attraction of the earth upon the sun, because of the presence of the sun : there remains the case of the power, or the efficient source of the power, having pre-existed in the sun (or the earth) before the earth (or the sun) was in presence. In the latter view it appears to me that, consistently with the conservation of force, one of three sub-cases must occur : either the gravitating force of the sun, when directed upon the earth, must be removed in an equivalent degree from some other bodies, and when taken off from the earth (by the disappearance of the latter) be disposed of on some other bodies ; — or else it must take up some neiv form of power when it ceases to be gravi- tation, and consume some other form of power when it is developed as gravitation ; — or else it must be always existing around the sun through infinite space. The first sub-case is not imagined by the usual hypothesis of gravitation, and will hardly be supposed probable : for, if it were true, it is scarcely possible that the effects should not have been observed by astronomers, when considering the motions of the planets in different positions with respect to each other and the sun. Moreover, gravitation is not assumed to be a dual power, and in them only as yet have such removals been observed by experiment or conceived by the mind. The second sub-case, or that of a new or another form of power, is also one which has never been imagined by others, in association with the theory of gravity. I made some endeavours, experimentally, to connect gravity with electricity, having this very object in view {Phil. Trans. 1851, p. 1) ; but the results were entirely negative. The view, if held for a moment, would imply that not merely the sun, but all matter, whatever its state, would have extra powers set up in it, if removed in any degree from gravitation ; that the particles of a comet at its perihelion would have changed in character, by the conversion of some portion of their molecular force into the increased amount of gravitating force which they would then exert ; and that at its aphelion, this extra gravitating force would have been converted back into some other kind of molecular force, having either the former or a new character : the conversion either way being to a perfectly equivalent degree. One could not even conceive of the diffusion of a cloud of dust, or its concentration into a stone, without supposing something of the same kind to occur ; and I suppose that nobody will accept the idea as possible. The third sub-case remains, namely, that the power is always existing around the sun and through infinite space, whether secondary bodies be there to be acted upon by giavitation or not : and not only around the sun, but around every particle of matter which has existence. This case of a constant necessary condition to action in space, when as respects the sun the earth is not in place, and of a certain gravitating action as the result of that pre- 1855.] P'Tof, Tyndall on Magnetic Repulsion. 13 vious condition when the earth is in place, I can conceive, con- sistently, as I think, with the conservation of force : and I think the case is that which Newton looked at in gravity ; is, in philosophical respects, the same as that admitted by all in regard to light, heat, and radiant phenomena ; and (in a sense even more general and extensive) is that now driven upon our attention in an especially forcible and instructive manner, by the phenomena of electricity and magnetism, because of their dependence on dual forms of power. Jan. 22, 1855. [M. F.] WEEKLY EVENING MEETING, Friday, January 26. William Robert Grove, Esq. M.A. Q.C. F.R.S. Vice-President, in the Chair. Professor Tyndall, F.R.S. On the Nature of the Force by which Bodies are Repelled from the Poles of a Magnet. The Lecturer commenced, by showing that bodies are repelled by the poles of a magnet, in virtue of a state of excitement into which they are thrown by the latter. The repulsion of bismuth, and the attraction of soft iron, followed precisely the same laws when the strength of the influencing magnet was augmented, the respective forces being pronortional, not simply to the strength, but within wide limits, to tne square of the strength of the magnet. The result is explained in the case of iron by the fact of its being con- verted, while under magnetic influence, into a true temporary magnet, whose power varies with that of the influencing one ,- and in the case of bismuth, the result can only be explained by the fact that the dia-magnetic mass is converted into a true dia-magnet. It was next shown that the condition of excitement evoked by a magnetic pole was not the same as that evoked by another pole of an opposite quality. If the repulsion were independent of the quality of the pole, then two poles of unlike names ought to repel the bismuth, when brought to act upon it simultaneously. This is not the case. Two poles of the same name produce repul- sion ; but when they are of equal powers and opposite names, the condition excited by one of them is neutralized by the other, and no repulsion follows. Bars of magnetic and dia-magnetic bodies were next submitted 14 Professor Tyndall [Jan. 26, to all the forces capable of acting upon them magnetically ; first, to the magnet alone ; secondly, to the electric current alone ; and, thirdly, to the magnet and current combined. Attention to struc- ture was here found very necessary, and the neglect of it appears to have introduced much error into this portion of science. Powdered bismuth, without the admixture of any foreign ingredient, was placed in a strong metallic mould, and submitted to the action of a hydraulic press ; perfectly compact metallic masses were thus pro- cured, which, suspended in the magnetic field with the line of com- pression horizontal, behaved exactly like magnetic bodies, setting their longest dimensions from pole to pole. This identity of deportment with an ordinary magnetic substance was also exhibited in the case of the electric current, and of the current and the magnet combined. In like manner, by the compression of a mag- netic powder magnetic bars were produced, which, between the two poles of a magnet, set exactly like ordinary dia-magnetic ones ; this identity of deportment is preserved when the bars are submitted to the action of the current, and of the current and magnet combined. Calling those bars which show the ordinary magnetic and dia- magnetic action normal bars, and calling the compressed bars abnormal ones, the law follows, that an abnormal bar of one class of bodies exhibits precisely the same deportment, in all cases, as the normal bar of the other class ; but when we compare normal bars of both classes together, or abnormal bars of both classes, then the antithesis of action is perfect. The experiments prove that, if that which Gauss calls the ideal distribution of magnetism in magnetic bars be inverted, we have a distribution which will pro- duce all the phenomena of dia-magnetic ones. The important question of dia-magnetic polarity was submitted to further and stricter examination. A flat helix, whose length was an inch, internal diameter an inch, and external diameter seven inches, was attached firmly to a table, with its coils vertical. A suspension was arranged by means of which a bar of bismuth, five inches long, and 0*4 of an inch in diameter, was permitted to swing freely, while surrounded by the helix. With this arrange- ment, the following experiments were, or might be made: — 1. A voltaic current from twenty of Grove's cells was sent through the helix h, the direction of the current in the upper half of the helix being that denoted by the arrow (Fig. 1). The north pole of a magnet being placed at N, the end a of the suspended bar of bismuth, a b, was attracted towards the pole N. 2. The south pole of a second magnet being placed at S, and the cur- rent being sent through the helix in the h same direction as before, the bar left its central position and approached N with greater force than in the Fig. 1. a j^ s. s g=^ fr=^ n' \. 1855.] on Magnetic Repulsimi. ' 15 former experiment. The reason was deemed manifest : the state of excitement which causes a to be attracted by N causes it to be repelled by S ; both poles, therefore, act in unison, and a deflection of greater energy is produced. 3. The pole S being removed to the position S', the deflection was also found to be about twice as forcible as when the single pole N was employed. Here also the reason is plain : the two ends, a and b, of the bismuth bar, are in diiierent states of excitement ; the end a is attracted by a north pole, the end b is attracted by a south pole : both poles act therefore as a mechanical couple upon the bar, and produce the deflection observed. 4. The pole S' was replaced by a north pole of the same strength, thus bringing two poles of the same name to bear upon the two ends of the bar : there was no deflection by this arrangement ; it is manifest that N s attraction for the end a was nullified by the repulsion of the end 6 by a like pole ; the experi- ment thus furnishes an additional proof of the polar condition of a b. 5. We have supposed the pole S to be removed into the position S' ; but permitting the pole S to remain, and introducing another pole (a south one) at S', a greater action than that produced with two magnets was obtained. 6. Finally, adding another north pole at N', and allowing four magnets to operate upon the bismuth bar simultaneously, a maximum action was obtained, and the bar was attracted and repelled with the greatest promptness and decision. I7i all these cases where an iron bar was substituted for the bismuth bar a b, a deflection precisely the opposite to that exhibited by a b wa^ produced. A branch of the current by which the bar of bismuth was surrounded could be suffered to circulate round a bar of iron, suspended freely in an adjacent helix ; when the forces acting upon the iron were the same as those acting upon the bismuth, the bars were always deflected in opposite directions. The question of dia-magnetic polarity was next submitted to a test which brought it under the dominion of the principles of me- chanics. A mass of iron was chosen for the moveable magnetic pole, of such a shape that the diminution of the force emanating from the pole, as the distance was augmented, was very slow ; or in other words, the field of force was very uniform. Let the space in front of the pole P, (Fig. 2.) be such ^ a field. A normal bar of bismuth, a b, was attached to the end of a lever transverse to the length of the latter, and counterpoised by a weight at the other extremity : the system was then suspended from its centre of gravity ^, so that the beam and bar swung horizontally. Supposing the bar to oc- cupy the position shown in the figure, then if the force acting upon it be purely repulsive — that is to say, if the dia-magnetic force be unpolar — it is evident that the tendency 16 Prof. Tyndall on Magnetic Repulsion. [Jan. 26, N of the force acting upon every particle of the mass of bismuth tends to turn the lever round its axis of suspension, in the direction of the curved arrow. On exciting the magnetism of P, however, a precisely contrary motion is observed — the lever approaches the pole. This result, which, as far as the lecturer could see, was perfectly inexplicable on the assumption that the dia-magnetic force was purely repulsive, is explained in a simple and beautiful manner on the hypothesis of dia-magnetic polarity. According to this, the end b of the bar of bismuth is repelled by P, and the end a is attracted : but the force acting upon a is applied at a greater distance from the axis of suspension than that acting upon b ; and as it has been arranged that the absolute in- tensities of the forces acting upon the two ends differ very slightly from each other, the mechanical advantage possessed by a gives to it the greatest moment of rotation, and the bar is attracted instead of repelled. Let a mag- netic needle n s (Fig. 3,) be attached like the bar a b (Fig. 2) to a lever, and submit- ted to the earth's magnetism. Let the north pole of the earth be towards N ; the action of the pole upon n is attractive, upon s repulsive, the absolute intensities of these forces are the same, inasmuch as the length of the needle is a vanishing quantity in comparison with its distance from the pole N : hence the mechanical advantage possessed by the force acting upon s, on ac- count of its greater distance from the axis of rotation, causes the lever to recede from N, and we obtain a result perfectly analogous to that obtained with the bar of bismuth (Fig. 2).* [J. T.] Fig. 3. * A paper submitted to the Koyal Society last November, and a portion of which formed the subject of the Bakerian Lecture for the present year, con- tains a more comprehensive discussion of this subject. In it are explanations, which it is hoped will be deemed satisfactory, of the difficulties adduced by M. Matteucci, in his instructive Cours Special^ recently published. 1855.] Pendulum-experiments at Harton Collierr, 17 WEEKLY EVENING MEETING, Friday, February 2. Sir Henry Holland, Bart. M.D. F.R.S. Vice-President, in the Chair. G. B. Airy, Esq. F.R.S. Astronomer-Royal, On the Pendulum-experiments lately/ made in the Harton Colliery, for ascertaining the mean Density of the Earth. The speaker commenced with remarking that the bearing of the experiments, of which he was about to give a notice, was not limited to their ostensible object, but that it applied to all the bodies of the Solar system. The professed object of the experiments was to obtain a measure of the density of the earth, and therefore of the mass of the earth (its dimensions being known) ; but the ordinary data of astronomy, taken in conjunction with the laws of gravitation, give the proportions of the mass of the earth to the masses of the sun and the principal planets ; and thus the determination of the absolute mass of the earth would at once give determinations of the absolute masses of the sun and planets. To show how this proportion is ascertained, it is only necessary to remark, that a planet, if no force acted on it, would move in a straight line ; that, therefore, if we compute geometrically how far the planet moves in a short time, as an hour, and then compute the distance between the point which the planet has reached in its curved orbit, and the straight line which it has left, we have found the displacement which is produced by the sun*s attraction, and which is therefore a measure of the sun's attraction. In like manner, if we apply a similar calculation to the motion of a satellite during one hour, we have a measure of the attraction of its primary. The comparison of these two gives the proportion of the attraction of the sun, as acting upon a body, at one known distance, to the attraction of a planet, as acting upon a body at another known distance. It is then necessary to apply one of the theorems of the laws of gravitation, namely, that the attraction of every attracting body is inversely as the square of the distance of the attracted body ; and thus we obtain the proportion of the attractions of the sun and a planet, when the bodies upon which they are respectively acting are at the same distance from both : and finally, it is necessary to apply another theorem of the law of gravitation, namely, that tlie attractions thus found, corresponding to equal distances of the Vol. II. c 18 The Astronomer- Royal on the [Feb. 2, attracted bodies, are in the same proportion as the masses of the attracting bodies (a theorem which applies to gravitation, but does not apply to magnetic and other forces). Into the evidence of these portions of the law of gravitation, the speaker did not attempt to enter : he remarked only that they rest upon very complicated chains of reasoning, but of the most certain kind. His only object was to show that tlie proportion of the masses of all bodies, which have planets or satellites revolving round them, can easily be found — (the proporfion for those which have no satellites is found by a very indirect process, and with far less accuracy) ; and that if the absolute mass of the earth be known, the absolute mass of each of the others can be found. As their dimensions are known, their densities can then be found. Thus it rests upon such inquiries as those on which this discourse is to treat, to determine (for instance) whether the planet Jupiter is composed of materials as light as water, or as light as cork. The obvious importance of these determinations had induced philosophers long since to attempt determinations of the earth's density : and two classes of experiments had been devised for it. The first class (of which there was only one instance) is the attraction of a mountain, in the noble Schehallien experiment. It rests, in the first place, upon the use of the zenith sector ; and, in the next place, upon our very approximate knowledge of the dimensions of the earth. [The construction of the zenith sector was illustrated by a model : and it was shown, that if the same star were observed at two places, the telescope would necessarily be pointed in the same direction at the two places, and the difference of direc- tion of the plumb line, as shown by the different points of the graduated arc which it crossed at the two places, would show how much the direction of gravity at one place is inclined to the direction of gravity at the other place.] Now, from our knowledge of the form and dimensions of the earth, we know that the direction of gravity changes very nearly one second of angle for every 100 feet of horizontal distance. Suppose then, that two stations were taken on Schehallien, one on the north side and the other on the south side, and suppose that their distance was 4000 feet ; then, if the direction of gravity had not been influenced by the mountain, the Inclination of the directions of gravity at these two places would have been about 40 seconds. But suppose, on applying the zenith sector in the way just described, the inclination was found to be really 52 seconds. The difference, or 12 seconds, could only be explained by the attraction of the mountain, which, combined with what may be called the natural direction of gravity, produced directions inclined to these natural directions. In order to infer from this the density of the earth, a calculation was made (founded upon a very accurate measure of the mountain) of what would have been the disturbing effect of the mountain if the mountain had been as dense as the interior of the earth. It was found that the dis- 1855.] Pendulum-experiments at Harton Colliery. 19 turbance would have been about 27 seconds. But tlie disturbance was really found to be only 12 seconds. Consequently the proportion of the density of the mountain to the earth's density was that of 12 to 27, or 4 to 9 nearly. And from this, and the ascertained density of the naountain, it followed that the mean specific gravity of the earth would be about five times that of water. The only objection to this admirable experiment is, that the form of the country near the mountain is very irregular, and it is difficult to say how much of the 12 seconds is or is not really due to Schehallien. The second class is what may be called a cabinet experiment, possessing the advantage of being extremely manageable, and the disadvantage of being exceedingly delicate, and liable to derange- ment by forces so trifling that they could with difficulty be avoided. Two small balls upon a light horizontal rod were suspended by a wire, or two wires, forming a torsion balance, and two large leaden balls were brought near to attract the small balls from the quiescent position. We could make a calculation of how far the great balls would attract the little ones, if they were as dense as the general mass of the earth ; and comparing this with the distance to which the leaden balls really do attract them, we find the proportion of the density of the earth to the density of lead. The peculiar difficulty and doubt of the results in this experiment depend on the liability to disturbances from other causes than the attraction of the leaden balls, especially the currents of air produced by the approach of bodies of a different temperature ; and after all the cautions of Cavendish, Reich, and Baily, in their successive attempts, it seems not impossible that the phaenomena observed may have been produced in part by the temperature of the great balls as well as their attraction. These considerations induced Mr. Airy, in 1826, to contem- plate a third class of experiments, namely, the determination of the difference of gravity at the top and the bottom of a deep mine, by pendulum experiments. Supposing the difference of gravity found, its application to the determination of density (in the simplest case) was thus explained. Conceive a spheroid concentric with the ex- ternal spheroid of the earth to pass through the lower station in the mine. It is easily shown that the attraction of the shell included between these produces no effect whatever at the lower station, but produces the same effect at the upper station as if all its matter were collected at the earth's centre. Therefore, at the lower station we have the attraction of the interior mass only : at the upper station we have the attraction of the interior mass (though at a greater distance from the attracted pendulum) and also the attrac- tion of the shell. It is plain that by making the proportion of these theoretical attractions equal to the proportion actually observed by means of the pendulum, we have the requisite elements for finding the proportion of the shell's attraction to the internal mass's attrac- tion, and therefore the proportion of the matter in the shell to the c 2 20 Tfie Astronomer-Royal on the [Feb. 2, matter in the internal mass ; from which the proportion of density is at once found. Moreover, it appeared probable, upon estimating the errors to which observations are liable, that the resulting error in the density, in this form of experiment, would be less than in the others. Accordingly, in 1826, the speaker, with the assistance of his friend Mr. Whewell (now Dr. Whewell), undertook a series of expe- riments at the depth of nearly 1200 feet, in theDolcoath mine, near Camborne, in Cornwall. The comparison of the upper and lower clocks (to which further allusion will be made) was soon found to be the most serious difficulty. The personal labour was also very great. They had, however, made a certain progress when, on rais- ing a part of the instruments, the straw packing took fire — (the origin of the fire is still unknown), — and partly by burning, and partly by falling, the instruments were nearly destroyed. In 1828 the same party, with the assistance of Mr. Sheepshanks and other friends, repeated the experiment in the same place. After mastering several difficulties, they were stopped by a slip of the solid rock of the mine, which deranged the pumps and finally flooded the lower station. The matter rested for nearly twenty-six years, the principal progress in the subjects related to it being the correction to the computation of " buoyancy " of the pendulum, determined by Colonel Sabine's experiments. But in the spring of 1854, the manipulation of galvanic signals had become familiar to the As- tronomer Royal, and the Assistants of the Greenwich Observatory, and it soon occurred to him that one of the most annoying diffi- culties in the former experiment might be considered as being practically overcome, inasmuch as the upper and lower clocks could be compared by simultaneous galvanic signals. Inquiries, made in the summer, induced him to fix on the Harton colliery near South Shields, where a reputed depth of 1260 feet could be obtained ; and as soon as this selection was known, every possible facility and assistance were given by the owners of the mine. Arrangements were made for preparing an expedition on a scale sufficient to over- come all anticipated difficulties. A considerable part of the ex- pense was met by a grant from the Board of Admiralty. The Electric Telegraph Company, with great liberality, contributed (unsolicited) the skill and labour required in the galvanic mount- ings. The principal instruments were lent by the Royal Society. Two observers were furnished by the Royal Observatory, one by the Durham Observatory, one by the Oxford Observatory, one by the Cambridge Observatory, and one by the private observatory of Red Hill (Mr. Carrington's). Mr. Dunkin, of the Royal Observa- tory, had the immediate superintendence of the observations. The two stations selected were exactly in the same vertical, ex- cellently walled, floored, and ceiled ; the lower station, in particular, was a most comfortable room or rather suite of rooms. Every 1855.] Pendulum-experiments at Harton Colliery. 21 care was taken for solidity of foundation and steadiness of tem- perature. In each (the upper and the lower) was mounted an invariable brass pendulum, vibrating by means of a steel knife edge upon plates of agate, carried by a very firm iron stand. Close behind it, upon an independent stand, was a clock, carrying upon the bob of its pendulum an illuminated disk, of diameter nearly equal to the breadth of the tail of the invariable pendulum ; and between the two pendulums was a chink or opening of two plates of metal, which admitted of adjustment, and was opened very nearly to the same breadth as the disk. To view these, a telescope was fixed in a wall, and the observer was seated in another room. When the invariable pendulum and the clock pendulum pass the central points of vibration at the same instant, the invariable pen- dulum hides the illuminated disk as it passes the chink, and it is not seen at all. At other times it is seen in passing the chink. The observation, then, of this disappearance determines a coinci- dence with great precision. Suppose the next coincidence occurs after 400 seconds. Then the invariable pendulum (swinging more slowly), has lost exactly two swings upon the clock pendulum, or the proportion of its swings to those of the clock pendulum is 398 : 400. If an error of a second has been committed, the pro- portion is only altered to 397 : 399, which differs by an almost insignificant quantity. Thus the observation, in itself extremely rude, gives results of very great accuracy. As the proportion of invariable-pendulum-swings to clock-pendulum-swings is thus found, and as the clock-pendulum-swings in any required time are counted by the clock dial, the corresponding number of in- variable-pendulum-swings is at once found. Corrections are then required for the expansion of the metal (depending on the ther- mometer-reading), for the arc of vibration, and for the buoyancy in air (depending on the barometer-reading). But when the corrected proportion of upper-invariable-pendulum- swings to upper-clock-pendulum-swings is found, and the proportion of lower-invariable-pendulum-swings to lower clock-pendulum- swings is found, there is yet another thing required : — namely, the proportion of upper-clock-pendulum-swings to lower-clock- pendulum-swings in the same time ; or, in other words, the pro- portion of the clock rates. It was for this that the galvanic signals were required. A galvanometer was attached to each clock, and an apparatus was provided in a small auxiliary clock, which com- pleted a circuit at every 15 seconds nearly. The wire of this circuit, passing from a small battery through the auxiliary clock, then went through the upper galvanometer, then passed down the shaft of the mine to the lower galvanometer, and then returned to the battery. At each galvanometer there was a small apparatus for breaking circuit. At times previously arranged, the circuit was completed by this apparatus at both stations, and then it was the duty of the observers at both stations to note the clock times of 22 Pendulum-eotperimeiits at Harton Colliery. [Feb. 2, the same signals; and these evidently give comparisons of the clocks, and therefore give the means of comparing their rates. Tlius (by steps previously explained), the number of swings made by the upper pendulum is compared with the number of swings made in the same time by the lower pendulum. Still the result is not complete, because it may be influenced by the peculiarities of each pendulum. In order to overcome these, after pendulum A had been used above and pendulum B below, they were reversed ; pendulum B being observed above and A below ; and this, theoretically, completes the operation. But in order to insure that the pendulum received no injury in the inter- change, it is desirable again to repeat the experiments with A above and B below, and again with B above and A below. In this manner the pendulums were observed with 104 hours of incessant observations, simultaneous at both stations, A above and B below ; then with 104 hours, B above and A below ; then with 60 hours, A above and B below ; then with 60 hours, B above and A below. And 2454 effective signals were observed at each station. The result is, that the pendulums suffered no injury in their changes ; and that the acceleration of the pendulum on being carried down 1260 feet is 2f seconds per day, or that gravity is increased by — ^ part. It does not appear likely that this determination can be sensibly in error. The circumstances of experiment were, in all respects, extremely favourable ; the only element of constant error seems to be that (in consequence of the advanced season of the year), the upper station was cooler by 7° than the lower station, and the temperature-reductions are therefore liable to any uncertainty which may remain on the correction for 7^. The reductions em- ployed were those deduced by Sabine from direct experiment, and their uncertainty must be very small. If a calculation of the earth's mean density were based upon the determination just given, using the simple theory to which allusion is made above, it would be found to be between six times and seven times the density of water. But it is necessary yet to take into account the deficiency of matter in the valley of the Tyne, in the hollow of Jarrow Slake, and on the sea-coast. It is also necessary to obtain more precise determinations of the specific gravities of the rocks about Harton colliery than have yet been procured. Measures are in progress for supplying all these de- ficiencies. It seems probable that the resulting number for the earth's density will probably be diminished by these more accurate estimations. [G. B. A.] 1855.] General Monthly Meeting. 23 GENERAL MONTHLY MEETING, Monday, Febriuary 5. William Pole, Esq. M.A. F.R.S. Treasurer and Vice-President, in the Chair. Edmund Macrory, Esq. Henry Maudslay, Esq. Hensleigh Wedgwood, Esq., and John William Wrey, Esq. M.A. were duly elected Members of the Royal Institution. Richard Hoper, Esq., and Henry Pemberton, Esq. were admitted Members of the Royal Institution. The following Presents were announced, and the thanks of tlie Members returned for the same : — From Her Majesti/'s Government— CsLtalogues of the Stars near the Ecliptic observed at Markree, in 1852-4. 8vo. 1854. Actuaries^ Institute of— The Assurance Magazine, No. 18. 8vo. 1854. Andrews, J. R. Esq. (the Author) — Four Months' Tour in the East. 12mo. 1853. Art-Union of London — Report for 1854. 8vo. Almanacs for 1855. 32nio. Asiatic Society of Bengal— Journal, Nos. 242, 243. 8vo. 1854. Astronomical Society — Monthly Notices. Vol. XV. Nos. 1,2. 8vo. 1854-5. Bache, Dr. A. D. (the Author) — Annual Report of the Superintendent of the Coast Survey (of the United States), 1851 and 1852. With Charts. 1 vol. 8vo. and 2 vols. 4to. Washington, 1852-3 Bell, Jacob, Esq. M.E.I. — Pharmaceutical Journal, Dec. 1854, and Jan. 1855. 8vo. Boosey, Messrs. {the Publishers)— The Musical World for December, 1854, and January, 1855. 4to. British Architects, Royal Institute o^— Proceedings in December, 1854, and January, 1855. 4to. Brodhurst, Bernard E. Esq. M.R.I, (the Author)— The Lateral Curvature of the Spine, its Pathology and Treatment. 16mo. 1855, Brodie, Sir Benjamin C. Bt. D.C.L. F.R.S. M.R.I (the Author)— Vsycholo- gical Enquiries : in a Series of Essays intended to illustrate the Mutual Relations of the Physical Organisation and the Mental Faculties. 2nd Edition. 16mo. 1855. Chemical Society— Qnarterly Journal. No. 28. 8vo. 1854. Civil Engineers, Institution 0/"— Proceedings for Dec. 1854, and Jan. 1855. 8vo. Cox, Alfred^ Esq. (the Author)— The lAnAlord'sdLndTen&nt'sGmde. 8vo. 1853. 24 General Monthly Meeting. [Feb. 5, East India Company y Hon. — Meteorological Observations at Madras in 1846-50. 4to. 1854. Editors — The Medical Circular for December, 1854, and January, 1855. 8vo. The Athenaeum for Decenaber, 1854, and January, 1855. 4to. The Practical Mechanic's Journal for December, 1854, and Jan. 1855. 4to. The Mechanic's Magazine for December, 1854, and January, 1855. 8vo. The Journal of Gas-Lighting for December, 1854, and January, 1855. 4to. Deutsches Athenaum, for December, 1854, and January, 1855. 4to. The Church of England Quarterly Review, January, 1855. 8vo. Faradai/f Professor, D.C.L. F.R.S. — Monatsbericht der Konigl. Preuss. Akademie, Septenaber zu November, 1854. 8vo. Berlin. Kaiserliche Akademie der Wissenschaften, Wien : — Philosophisch-Historische C/asse :—Sitzungsberichte. Band XII. Heft 5. 8vo. 1854. Archiv fiir Kunde CEsterreichischer Geschichts-Quellen. Band XIII. 8vo. 1854. Notizenblatt. (Beilage zum Archiv.) 1854. Nos. 18-24. 8vo. Monumenta Habsburgica. Erste Abtheilung. Band I. 8vo. 1854. Mathematisch-Naturwissenschqftliche Classe : — Sitzungsberichte. Band XII. Heft 5 ; Band XIII. ; und Register zu Bande I-X. 8vo. 1854. Geognostische Karte der Umgebungen von Krems und vom Manhardsberge. Von J. Czjek. 1854. Memoria sobre las causas Meteorologico-Fisicas que producen las constantes sequias de Murcia y Almeria : su Autor Don Manuel Rico y Sinobas. 8vo. Madrid, 1851. Etudes Chimiques sur les Eaux Pluviales et sur I'Atmosphere de Lyon, &c. Par A. Bineau. 8vo. Lyon, 1854. Memoires relatifs k FAssaiuissement des Ateliers, des Edifices publics et des Habitations particulieres. Par J. P. J. D'Arcet. 4to. Paris, 1853. Rapport sur les Tapisseries et les Tapis des Manufactures Nationales, &c. Par M. Chevreul. 8vo. Paris, 1854. An Essay explanatory of the Tempest Prognosticator. By G. Merryweather, M.D. (the Inventor). 8vo. 1851. Maritime Conference held at Brussels for devising a uniform System of Me- teorological Observations at Sea. 4to. 1 853. Franklin Institute of Pennsylvania — Journal, Vol. XXVIII. Nos. 5, 6. Svo. 1 854. Graham, George, Esq. Heyistrar- General — Report of the Registrar-General for December, 1854, and January, 1855. 8vo. Granville, A. B. M.D. F.E.S. M.R.I, {the Author)— SnMen Death. 12mo. 1855. Hargraves, E. H. Esq. (the Author)— Austvalia. and its Gold Fields. 16mo. 1855. Highley, Mr. {the PwftZfs^cr')— Botanical Letters to a Friend, by Dr. F. linger, translated by D. B. Pauf. 16mo. 1853. The Microscope, in its adaptation to Vegetable Anatomy and Physiology : by Dr. H. Schacht; translated by F. Currey. 16mo. 1853. Leake, Lieut. -Colonel W. M. F.R.S. M.R.I, {the Author)— A Letter to Col. Chesney, and a Postscript. Svo. 1854-5. Linnean Society of London — Transactions, Vol, XXI. Part 3. 4to. 1854. Proceedings, Nos. 52-58. 8vo. 1853-4. Annual Address of the President, 1854. 8vo. Liverpool Literary and Philosophical Society — Proceedings, No. 8. Svo. 1854. London University — London University Calendar, 1855. 12mo. Lovell, E. B. Esq. M.R.I, {the Editor)— The Common Law and Equity Reports. Part XXII. Svo. 1854. Marcet, W. M D. {the Author) — Account of the Organic Chemical Constituents, or Immediate Principles of the Excrements of Man and Animals in the Healthy State. (From Phil. Trans. Roy. Soc. 1854.) 4to. 1854. 1855.] General Ma/Uhly Meeting. 25 Morley^ R. Reginald, Esq. M.R.I. — Descriptive Catalogue of Historical MSS. in the Arabic and Persian Languages in the Library of the Royal Asiatic Society. By W. H. Moriey. 8vo. 1854. Digest of Indian Cases. New Series Vol. L By W. H. Moriey. Svo. 1852. Morris, //. Sutherland, Esq., M.R.I. — Vesalii Opera Omnia Anatomica et Chi- rurgica cura H. Boerhaave et B. S. Albini. 2 vols. fol. Lug. Bat. 1725. Novella, Mr. (the Publisher) — The Musical Times for December, 1854, and January, 1855. 4to. Orr, Messrs. and Co. (the Publishers) — The Theory and Practice of Landscape Painting in Water Colours. By G. Barnard. 8vo. 1855. Peterviann, A. Esq. (the Author) — Karte des Eui'opaischen Kusslands und der Angrenzenden Lander, 1855. Photographic Society — Journal, Nos. 24-26. 8vo. 1854-5. Quaritch, Mr. B. (the Publisher) — Early Christianity in Arabia: an Historical Essay. By T. Wright, Esq. F.S.A. 8vo. 1855. Reeves, Evans, M.D. (tlie Author) — Diseases of the Stomach. 12mo. 1854. Reid, P. Sandeman, Esq. (the Author) — On Practice with Gas at Blowers. 8vo. 1854. Roi/al Society of Edinburgh— Trsinsactians, Vol. XXI. Parti. 4to. 1854. Proceedings, No. 44. 8vo. 1853-4. Scoffern, John, M.B. (the E'difor)— The Subject-Matter of a Course of Ten Lectures on Organic Chemistry applied to the Arts, delivered at the Royal Institution in 1852, by W. T. Brande, Esq. 16mo. 1854. Society of Arts — Journal for December, 1854, and January, 1855. 8vo. Soret, M. L. (the Author) — Sur la Decomposition des Sels du Cuivre par la Pile. 8vo. 1854. Sylvester, J. J. M.A. F.R.S. (the Author) — A Probationary Lecture on Geometry, delivered before the Gresham Committee, Dec. 4th. 8vo. 1854. Taylor, Rev. W. F.R.S. il/.i?./.— Magazine for the Blind, December, 1854, and January, 1855. 4to. Thoughts and Fancies in Solitary Hours. By C. R. Lambert. 8vo. 1840. Zopf und Schwert. Historisches Lustspiel von K,Gutzkow. 16mo. Leipzig, 1850. Vincent, Mr. B. (Assistant Secretary, R.I.) — Doderlein's Handbook of Latin Synonyms Translated by the Rev. H. H. Arnold. Svo. 1841. Essay on Education, by J. Whitchurch. 16mo. 1772. Voyage Pittoresque des Environs de Paris. Par M. D***. 12mo. Paris, 1762. Traits Elementaire de I'lmprimerie. Par A. F. Momoro. 8vo. Paris, 1786. Wrey, John W. Esq. M.A. M.R.I.—The Morality of Public Men. A Letter to the Earl of Derby. Svo. 1852. " Sans Changer," the real Basis of " The Morality of Public Men." A Snow- ball for « an Englishman." Thrown by I. W. W. Svo. 1853. 26 Professor Otvcfi on the [Feb. 9, WEEKLY EVENING MEETING, Friday, February 9. William Pole, Esq. M,A. F.R.S. Treasurer and Vice-President, in the Chair. Professor Owen, F.R.S. On tJie Anthropoid Apes, and their relatiotis to Man, In this discourse, the structure, more especially of the bones and teeth, of the most highly organised Apes — the Orang-utans and Chim- panzees— was compared with that of the Human Subject, in reference to the hypothesis that specific characters can be so far modified by external influences, operating on successive generations, as to produce a new and higher species of animal, and that thus there had been a gradual progression from the monad up to man. The conditions under which an active monad might be developed from dead mucus, or other organic matter in an infusion, or those that might influence and attend the transmutation of one recognised species into another — say of a polype into a medusa — were legiti- mate and important subjects of physiological research. But, hitherto, the results of such researches had not favoured the hypo- thesis of the coming in of species by spontaneous generation and transmutation. The last link in the chain of changes — from Quadrumana to JBimana — according to the latter old notion, the speaker had found alluded to by Henry More in his philosophical " Conjectura Cab- balistica;" and in reference to that, and other works of the same period, in which creative forces and the nature and origin of animal species were treated of, the equal spirit, vigorous intellect, profound learning, and laborious research of such men as Cudworth, More, and Grew, contrasted most favourably with the opposite character- istics of some works of the same kind of the present day. True it was that the old authors referred to exemplified the pre- valent belief of their age in witches and apparitions. But has not our age its clairvoyants and spirit-rappers ? Two centuries ago it was believed that a long round piece of wood, if bestridden by a person properly " possessed," would, under such influence, move against gravity, rise from the ground, and transport itself and its rider through the air. In our time it has been and may be still believed, that a flat circular piece of wood, on legs, can be made. 1855.] Anthropoid Apes y and their relations to Man. 27 by the imposition of hands of believers, to move against gravity, tilt up, and dance about. We know that this belief had become so scandalously prevalent, as to make our excellent friend, the FuUerian Professor, deem it worth his while to deal it a crushing blow of his intellectual sledge-hammer. The present age may be more knowing, but can it truly flatter itself as being wiser, more logical, and less credulous than that of Cudworth and More ? As numerous and respectable eye-witnesses, in the seventeenth century, vouched for the transit of witches on broomsticks through the air ; as, in the nineteenth, have testified to table-tilting and table-turning ! And whether the occult influence over-ruling the law of gravitation charges a discoid or cylindrical substance — oozes from the palm of the hand, or emanates from another part of the body — matters not. AVe ignore Satanic influences now-a-days, as a general rule. An impulse, said to be uncontrollable because uncontrolled, and a " black-cloud " over the mind, form grounds for acquitting the adulterous prolicide : of old, it would have been referred, in good earnest, to " the instigation of the devil," and an exemplary judgment would have followed the belief. It may be doubted whether the fear- fully increasing number of acquittals, and of " merciful recommend- ations " of murderers, be a sign of the superior wisdom_^and humanity of our times. But, returning to the sphere of that " lower wisdom, which rests in the contemplation of natural causes and dimensions," seeing that notions, refuted and repudiated centuries ago, are, in our day, revived and popularised, with a semblance of support from the later acquisitions of science, it is meet that they should be brought to the test of the exact results of modem inquiry : and this was the aim the Professor had in view in treating of the organical characters of the highest of the brute creation and their relations to those of the human species. For about two centuries, naturalists have been cognizant of a small ape, tailless, without cheek-pouches, and without the ischial callosities, clothed with black hair, with a facial angle of about 60°, and of a physiognomy milder and more human-like than in the ordinary race of monkeys, less capricious, less impulsive in its habits, more staid and docile. This species, brought from the West Coast of Africa, is that which our anatomist, Tyson, dissected : he described the main features of its organisation in his work published in 1699. He called it the Homo Sylvestris, or pigmy. It is noted by Linnaeus, in some editions of his Systema Nature, as the Homo Troglodytes. Blumenbach, giving a truer value to the condition of the innermost digit of the hind foot, which was like a thumb, called it the Simla Troglodytes; it afterwards became more commonly known as the " Chimpanzee." At a later period, naturalists became acquainted with a similar kind of ape, of quiet docile disposition, with the same sad, human- 28 Professor Owen on the [Feb. 9, like expression of features. It was brought from Borneo or Sumatra ; where it is known by the name of Orang, which, in the language of the natives of Borneo, signifies " man," with the distinctive addition of Outan^ meaning " Wood-man," or " Wild Man of the Woods." This creature differed from the pigmy, or Simla Tro- glodytes of Africa, by being covered with hair of a reddish-brown colour, and by having the anterior, or upper limbs, much longer in proportion, and the thumb upon the hind feet somewhat less. It was entered in the zoological catalogue as the Simla Satyrus. A governor of Batavia, Baron Wurmb, had transmitted to Holland, in 1780, the skeleton of a large kind of ape, tailless, like this small species from Borneo, but with a much-developed face, and large canine teeth, and bearing thick callosities upon the cheeks, giving it, upon the whole, a very baboon-like physiognomy ; and he called it the Pongo. At the time when Cuvier revised his summary of our knowledge of the animal kingdom, in his second edition of the Regne Ardmal, 1 829, the knowledge of the anthropoid apes was limited to these three forms. It had been suspected that the pongo might be the adult form of the orang; but Cuvier, pointing to its distinctive character, suggested that it could hardly be the same species. The facial angle of the small red orang of Borneo, and of the small black chimpanzee of Africa, brought them, from the predominant cranium, and small size of the jaws and small teeth, nearer than any other known mammalian animal to the human species, par- ticularly to the lower, or negro forms. It was evident, from the examination of these small chimpanzees and orangs, that they were the immature of some large species of ape. The small size and number of their teeth, (there being in some of the smaller specimens, only twenty, like the number of deciduous teeth in the human species,) and the intervals between those teeth, all showed them to be of the first or deciduous series. Professor Owen had availed himself of the rich materials in regard to these animals collected about that time by the Zoological Society, to investigate the state of dentition, and the state of the teeth— the permanent teeth — that might be hidden in the substance of the jaws, of both the immature orang- outang and the chimpanzee, and had found, that the germs of those teeth in the orang-outang agreed in size with the permanent teeth that were developed in the jaws of a species of pongo of Wurmb, which Sir Stamford Raffles had presented to the museum of the Col- lege of Surgeons some years before. Specimens of orangs since ac- quired, of an intermediate age, have shown the progressive change of the dentition. The skull of one of these was exhibited, showing the huge anterior incisors co-existing with the small milk canines. In the substance of the jaw are found the germs of the great canines, germs of large bicuspid teeth, showing the changes that must take place when the jaw is sufficiently enlarged to receive per- manent teeth of this kind ; and when the rest of the cranium is 1855.] Anthropoid Apes, and their relations to Man. 29 modified, as it must be, concomitantly for the attachment of mus- cles to work the jaw so armed, that all these changes must result in the acquisition of characters such as are presented by the skulls of the large pongo, or Bornean baboon-like ape. The specific identity of the pongo, with certain of the young orang-outangs, was thus satisfactorily made out, and is now admitted by all naturalists. With regard to the chimpanzee, the germs of similarly proportioned large teeth were also discovered in the jaws, likewise indicating that it must be the young of a much larger species of ape. The principal osteological characters of the chimpanzee and orang, commencing from the vertebral column, were as follows : — The vertebral column describes only one curve, inclining forwards, where it supports the head with its large jaws and teeth. The vertebrae in the neck, seven in number as usual in the mammalia, are chiefly remarkable for the great length of the simple spinous processes developed more than in most of the inferior apes, in relation to the necessities of the muscular masses that are to sus- tain and balance the head that preponderates so much forward on the neck. The vertebrae maintain a much closer correspondence in size, from the cervical to the dorsal and lumbar region, than in the human skeleton. With regard to the dorsal vertebrae, or those to which moveable ribs are articulated, there are twelve pairs in the orang ; seven of them send cartilages to join the sternum, which is more like the sternum in man than in any of the inferior quadru- mana : it is shorter and broader. In the smaller long-armed apes {Hylobates), which make the first step in the transition from the ordinary quadrumana to the man-like apes, the sternum is remark- ably broad and short. The lumbar vertebrae are five in number in this adult orang. The sacrum is broader than in the lower quad- rumana, but it is still narrow in comparison with its proportions in man. The pelvis is longer. The iliac bones are more expanded than in the lower quadrumana, but are more expanded on the same plane, and are flattened and long. The tuberosities of the ischia are remarkably developed, and project outwards. All these con- ditions of the vertebral column indicate an animal capable only of a semi-erect position, and present a modification of the trunk much better adapted for a creature destined for a life in trees, than one that is to walk habitually erect upon the surface of the ground. But that adaptation of the skeleton is still more strikingly shown in the unusual development of the upper prehensile extremities. The scapula is broad, with a well-developed spine and acromion ; there is a complete clavicle ; the bone of the arm {humerus) is of remark- able length, in proportion to the trunk ; the radius and the ulna are also very long, and unusually diverging, to give increased sur- face of attachment to muscles ; the hand is remarkable for the length of the metacarpus, and of the phalanges, which are slightly bent towards the palm ; the thumb is less developed than the cor- responding digit in the foot ; the whole hand is admirably adapted 30 Professm- Oiven on the [Feb. 9, for retaining a firm grasp of the boughs of trees. In the structure of the carpus, there is a well-marked difference from the human subject, and a retention of the character met with in the lower quadrumana ; the scaphoid bone being divided in the orang-outang. In the chimpanzee the bones of the carpus are eight, as in the human subject, but differ somewhat in form. If the upper ex- tremities are so extraordinary for their disproportionate length, the lower ones are equally remarkable for their disproportionate small- ness in comparison with the trunk, in the orang. The femur is short and straight, and the* neck of the thigh-bone comparatively short. The head of the thigh-bone in this animal, which requires the use of these lower prdiensible organs to grasp the branches of trees, and to move freely in many directions, is free from that ligament which strengthens the hip-joint in man ; the head of the femur in the orang is quite smooth, without any indication of that attach- ment. Here, again, the chimpanzee manifests a nearer approach to man, for the ligamentum teres is present in it, in accordance with the stronger and better development of the whole hind-limb. This approximation, also, is more especially marked in the larger development of the innermost of the five digits of the foot in the chimpanzee, which is associated with a tendency to move more fre- quently upon the ground, to maintain a more erect position than the orang-outang, and to walk further without the assistance of a stick. The foot, in both these species of anthropoid orangs, is characterised by the iDackward position of the ankle-joint, presented by the astra- galus to the tibia, which serves for the transference of the super- incumbent weight upon the foot ; by the comparatively feeble development of the backward projecting process of the calcaneum ; by the obliquity of the articular surface of the astragalus, which tends to incline the foot a little inwards, taking away from the plantigrade character of the creatures and from their capacity to support themselves in an erect position, and giving them an equi- valent power of applying their prehensible feet to the branches of the trees in which they live. With reference to the chimpanzee, it was further observed, that, although the number of the true vertebrae is the same as in the orang, yet there is an additional pair of ribs developed ; but, as there are thirteen dorsal vertebrae, we find only four lumbar ones. The modifications pf the pelvis are a close repetition of those of the orang-outang. The chief differences in the skeleton of the chimpanzee are, a shortening and strengthening of the upper extre- mities, an approach towards the characteristic proportions of those parts in man ; the presence of the ligamentum teres of the hip- joint ; and the greater development of the innermost toe in the foot. In both the orang and chimpanzee the skull is articulated by condyles, which are placed far back on its under surface. The cranium is small, characterised by well-developed occipital and sagit- tal ridges ; the occipital ridges in reference to the muscles sustaining 1 855.] A nthropoid Apes, and tJieir relations to Man. 3 1 the head ; and the sagittal ones in reference to an increased extent of the temporal muscles. The zygomatic arches are strong, and well arched outwards. The lower jaw is of great depth, and has powerful ascending rami, but the chin is wanting. The facial angle is about 50° to 55° in the full-grown simia satyrus, and 55° to 60° in the troglodytes niger. The difference in the facial angle between the young and adult apes, (which, in the young chimpanzee, approaches 60° to Q^"^,) depends upon those changes consequent upon the shed- ding of the deciduous teeth and the concomitant development of the jaws and intermuscular processes of the cranium. But the knowledge of the species of these anthropoid apes has been further increased since the acquisition of a distinct and precise cog- nisance of the characters of the adults of the orang and chimpanzee. First, in reference to the orangs of Borneo, specimens have reached this country which show that there is a smaller species in that island, the Simia Morio, in which the canines are less developed, in which the bony cristce are never raised above the level of the ordinary con- vexity of the cranium, and in which the callosities upon the cheeks are absent, associated with other characteristics plainly indicating a specific distinction. The Rajah Brooke has confirmed the fact of the existence in the island of Borneo of two distinct species of red orangs ; one of a smaller size and somewhat more anthropoid ; and the larger species presenting the baboon-like cranium. In reference to the black chimpanzee of Africa also, another very important addition has been made to our knowledge of those forms of highly developed quadrumana. In 1847 Professor Owen received a letter from Dr. Savage, a church-missionary at Gaboon, enclosing sketches of the crania of an ape, which he described as much larger than the chimpanzee, ferocious in its habits, and dreaded by the negro natives more than they dread the lion or any other wild beast of the forest. These sketches showed plainly one cranial characteristic by which the chimpanzee differs in a marked degree from the orangs ; viz. that produced by the prominence of the supra-orbital ridge, which is wanting in the adult and immature of the orangs. That ridge was strongly marked in the sketches trans- mitted. At a later period in the same year, Mr. Stuchbury trans- mitted to the Professor from Bristol two skulls of the same large species of chimpanzee, received from the same locality in Africa, bringing clearly to light evidence of the existence in Africa of a second larger and more powerful ape, — the troglodytes gorilla. This species presents the characters of the cranium which are seen in the immense development of the occipital and parietal cristae in relation to the muscles of the neck and jaws, — repeating, and even exaggerating, the prominence of the supra-orbital ridges of the chimpanzee, and showing the same characteristic inequality in the development of the teeth, particularly in the exaggerated size of the canine teeth, as in the great pongo of Wurmb. But the gorilla differs from the orang, and resembles man, first in the minor develop- 32 Professor Owen on the [Feb. 9, ment of the intermaxillary bone — that part being more produced in the orang-outang, giving it a less open facial angle ; it differs also in the form of the orbits, which in the orang-outang are a full oval, but in the gorilla square-shaped, more nearly approaching those in the human species ; it differs likewise in significant modifications of the base of the skull, as, for example, in tlie greater depth of the glenoid cavity, which joint, instead of being defended by merely the post- glenoid process in the inferior quadrumana, is now defended by a ridge developed from the tympanic bone, which ridge corresponds with the vaginal process in the human subject. In the conformation of the grinding surface of the teeth there is also a marked difference, which brings this great ape of Africa more nearly to the human subject, in reference to that character, than any other known species of the quadrumanous order. The characteristic of the grinding surface of the molar teeth in man, as may be seen in almost all varieties of the human species, is, that the four tubercles on the grinding surface are united by a ridge describing a strong sigmoid curvature. This is repeated in the gorilla, which also presents another important approach to the human subject in the commence- ment of a projection of the nasal bone. Like the chimpanzee, the superior extremities are longer than the lower ones ; and the inner- most digit of the foot is converted into a powerful thumb. Having premised this account of the mature characters of the different species of orangs and chimpanzees, the lecturer next pro- ceeded to contrast their structure with that of man. With regard to the dentition of these anthropoid apes, the number and kinds of the teeth, like those of all the quadrumana of the old world, correspond with those in the human subject ; but all these apes differ in the larger proportionate size of the eanine teeth, which necessitates a certain break in the series, in order that the prolonged points of the canine teeth may pass into their place when the mouth is completely closed. In addition to the larger proportionate size of the incisors and canines, the bicuspids in both jaws are implanted by three distinct fangs — two external and one internal : in the human species, the bicuspids are implanted by one external and one internal fang : in the highest races of man these two fangs are often connate ; very rarely is the external fang divided, as it constantly is in all the species of the orang and the chimpanzee. With regard to the catarrhine, or old-world quadrumana, the number of milk teeth is twenty, as in the human subject. But both chimpanzees and orangs differ from man in the order of develop- ment of the permanent series of teeth : the second true molar comes into place before either of the bicuspids have cut the gum, and the last molar is acquired before the permanent canine. We may well suppose that the larger grinders are earlier required by the frugivorous apes than by tlie omnivorous human race ; and one condition of the earlier development of the canines and bicuspids in man, may be their smaller relative size as compared 9^ 1 855.] A nthropoid Apes, and their relations to Man. 33 with the apes. The great difference is the predominant develop- ment of tlie permanent canine teeth, at least in the males of the orangs and chimpanzees ; for this is a sexual distinction, tlie canines in the females never presenting the same large proportion. In man, the dental system, although the formula is the same as in the apes, is peculiar for the equal length of the teeth, arranged in an uninterrupted series, and shows no sexual distinctions. The characteristics of man are exhibited in a still more important degree in the parts of the skeleton. His whole framework proclaims his destiny to carry himself erect ; the anterior extremities are liberated from any service in the mere act of locomotion, and are perfected to be the fitting instruments of the rational mind and free will with which he is endowed. The speaker proceeded to trace these modifications from the foundation upwards. With regard to the foot, it had been shown in a former discourse *' On the Nature of Limbs," that in tracing the manifold and pro- gressive changes of the feet in the mammalian series, in those forms where it is normally composed of five digits, the middle is usually the largest ; and this is the most constant one. The i^iodifications in the hind foot, in reference to the number of digits, are, first, the reduction and then the removal, of the innermost one ; then the corresponding reduction and removal of the outer one ; next, of the second and fourth digits, until it is reduced to the middle digit, as in the horse. The innermost toe, the first to dwindle and disappear in the brute series, is, in man, developed to a maximum of size, becoming emphatically the " great toe," one of the most essential cha- racteristics of the modifications of the human frame. It is made the powerful fulcrum for that lever of the second kind, which has its resistance in the tibio-astragalar joint, and the power applied to the projecting heel-bone : the superincumbent weight is carried further forwards upon the foot, by the more advanced position of the astragalus, than in the ape tribe ; and the heel-bone is much stronger, and projects more backwards. The arrangement of the powerfully-developed tarsal and meta- tarsal bones is such as to form a bony arch, of which the two piers rest upon the proximal joint of the great toe and the end of the heel. Well -developed cuneiform bones combine with the cuboid to form a second arch, transverse to the first. There are no such modifications in the orangs, in which the arch, or rather the bend of the long and narrow sole, extends to the extreme end of the long and curved digits, indicating a capacity for grasping. Upon these two arches the superincumbent weight of man is solidly and sufficiently maintained, as upon a low dome, with this further advantage, that the different joints, cartilages, coverings, and synovial membranes, give a certain elasticity to the dome, so that in leaping, running, or dropping from a height, the jar is diff'used and broken before it can be transmitted to affect the enormous Vol. II. ^D 84 Professor Owen on the [Feb. 9, brain-expanded cranium. The hind limbs in man are longer in proportion to the trunk than in any other known mammalian animal. The kangaroo might seem to be an exception, but if the hind limbs of the kangaroo are measured in relation to the trunk, they are shorter than in the human subject. In no animal is the femur so long in proportion to the leg as in man. In none does the tibia expand so much at its upper end. Here it presents two broad, shallow cavities, for the reception of the condyles of the femur. Of these condyles, in man only is the innermost longer than the outermost ; so that the shaft of the bone inclines a little outwards to its upper end, and joins a " neck " longer than in other animals, and set on at a very open angle. The weight of the body, received by the round heads of the thigh bones, is thus transferred to a broader base, and its support in the upright posture facilitated. There is also the collateral advantage of giving more space to those powerful adductor muscles that assist in fixing the pelvis and trunk upon the hind limbs. With regard to the form of the pelvis, you could not fully appreciate its peculiar modifications unless you saw it, as here displayed, in contradistinction to the form of the pelvis in the highest organised quadrumana. The short and broad ilium bends forwards, the better to receive and sustain the abdominal vis- cera, and is expanded behind to give adequate attachment to the powerful glutei muscles, which are developed to a maximum in the human species, in order to give a firm hold of the trunk upon the limbs, and a corresponding power of moving the limbs upon the trunk. The tuberosities of the ischium are rounded, not angular, and not inclined outwards, as in the ape tribe. The symphysis pubis is shorter than in the apes. The tail is reduced to three or four stunted vertebrae, anchylosed to form the bone called " os coccygis." The true vertebrae, as they are called in human anatomy, correspond in number with those of the chimpanzee and the orang, and in their divisions with the latter species, there being twelve thoracic, five lumbar, and seven cervical. This movable part of the column is distinguished by a beautiful series of sigmoid curves, con- vex forwards in the loins, concave in the back, and again slightly con- vex forwards in the neck. The cervical vertebrae, instead of having long spinous processes, have short processes, usually more or less bifurcated. The bodies of the true vertebrae increase in size from the upper dorsal to the last lumbar, which rests upon the base of the broad wedge-shaped sacrum, fixed obliquely between the sacro-iliac articulations. All these curves of the vertebral column, and the in- terposed elastic cushions, have relation to the libration of the head and upper limbs, and the diff'usion and the prevention of the ill effects from shocks in many modes of locomotion which man, thus organised for an erect position, is capable of performing. The arms of man are brought into more symmetrical proportions with the lower limbs ; and their bony framework shows all the per- fections that have been superinduced upon it in the mammalian 1855.] Anthropoid Apes, and their relations to Man. 35 series, viz., a complete clavicle, the antibrachial bones so adjusted as to permit the rotatory movements of pronation and supination, as well as of flexion and extension ; manifesting those characters which adapt them for the manifold application of that most perfect and beautiful of prehensile instruments, the hand. The scapula is broad, with the glenoid articulation turned outwards ; the clavi- cles are bent in a slight sigmoid flexure ; the humerus exceeds in length the bones of the fore-arm. The carpal bones are eight in number. The thumb is developed far beyond any degree exhibited by the highest quadrumana, and is the most perfect opposing digit in the animal creation. The skull is distinguished by the enormous expansion of the brain case ; by the restricted growth of the bones of the face, especially of the jaws, in relation to the small, equally- developed teeth ; and by the early obliteration of the maxillo- intermaxillary suture. To balance the head upon the neck-bone, we find the condyles of the occiput brought forward almost to the centre of the base of the skull, resting upon the two cups of the atlas, so that there is but a slight tendency to incline forwards when the balancing action of the muscle ceases, as when the head nods during sleep, in an upright posture. Instead of the strongly de- veloped occipital crest, we find a great development of true mastoid processes advanced nearer to the middle of the sides of the basis cranii, and of which there is only the rudiment in the gorilla. The upper convexity of the cranium is not interrupted by any sagittal or parietal cristas. The departure from the archetype, in the hu- man skull, is most conspicuous, in the vast expanse of the neural spines of the three chief cranial vertebrae, viz., occipital, parietal, and frontal. The Professor next entered upon the question, " To what extent does man depart from the typical character of his species ? " With regard to the kind and amount of variety in mankind, we find, propagable and characteristic of race, a difference of stature, a difference in regard to colour, difference in both colour and texture of the hair, and certain differences in the osseous framework. With regard to stature, the Bushmen of South Africa and the natives of Lapland exhibit the extreme of diminution, ranging from four to five feet. Some of the Germanic races and the Patagonian Indians exhibit the opposite extreme, ranging from six to seven feet. The medium size prevails generally throughout the races of mankind. With reference to the characteristics of colour, which are extreme, we have now opportunities of knowing how much that character is the result of the influence of climate. We know it more particu- larly by that most valuable mode of testing such influences which we have from the peculiarity of the Jewish race. For 1800 years that race has been dispersed into different latitudes and climates, and they have preserved themselves most distinct from any inter- mixture with the other races of mankind. There are some Jews still lingering in the valleys of the Jordan, having been oppressed d2 86 Professor Owen on the [Feb. 9, by the successive conquerors of Syria for ages, — a low race of people, and described by trustworthy travellers as being as black as any of the Ethiopian races. Others of the Jewish people, parti- cipating in European civilization, and dwelling in the northern nations, show instances of the light complexion, blue eyes, and light hair of the Scandinavian families. The condition of the Hebrews, since their dispersion, has not been such as to admit of much admixture by the proselytism of household slaves. We see, then, how to account for the differences in colour, without having to refer them to original or specific distinctions. As to the differ- ence in size in mankind, it is slight in comparison with what we observe in the races of the domestic dog, where the extremes of size are much greater than can be found in any races of the human species. With reference to the modifications of the bony structure, as characteristic of the races of mankind, they are almost confined to the pelvis and the cranium. In the pelvis the difference is a slight, yet apparently a constant one. The pelvis of the adult negro may sometimes be distinguished from that of the European by the greater proportional length and less proportional breadth of the iliac bones ; but how trifling is this difference compared with that marked distinction in the pelvis which the orang-outang pre- sents ! With regard to the cranial differences, the Professor selected for comparison three extreme specimens of skulls characteristic of race : one of an aboriginal of Van Diemen's Land (the lowest of the Melanian or dark-coloured family), a well-marked Mongolian, and a well-formed European skull. The differences were described to be chiefly these. In the low, uneducated, uncivilised races, the brain is smaller than in the higher, more civilised, and more educated races ; consequently the cranium rises and expands in a less degree. Concomitant with this contraction of the brain-case is a greater projection of the fore-part of the face ; whether it may be from a longer exercise of the practice of suckling, or a more habitual ap- plication of the teeth in the intef-maxillary part of the jaw, and in the corresponding part of the lower jaw, in biting and gnawing tough, raw, uncooked substances, — the anterior alveolar part of thQ jaws does project more in those lower races ; but still to an insigni- ficant degree compared with the prominence of that part of the skull in the large apes. And while alluding to them, the speaker again adverted to the distinction between them and the lowest of the human races, which is afforded by the inter-maxillary bone, already referred to. In the young orang-outang, even when th& change of dentition has begun, the suture between that bone and the maxillary is present ; and it is not until the large canine leeth are developed, that the stimulus of the vascular system, in the concomitant expansion and growth of the alveoli, tends to obliterate the suture. In the young chimpanzee, the maxillary suture disap- pears earlier, at least on the facial surface of the upper jaw. In 1855.] Anthropoid Apes^ and their relations to Mafi. 37 the human subject those traces disappear still earlier, and in regard to the exterior alveolar plates, the inter-maxillary and maxillary bones are connate. But there may be always traced in the human foetus the indications of the palatal and nasal portions of the maxillo-intermaxillary suture, of which the poet GoSthe was the first to appreciate the full significance. In the Mongolian skull there is a peculiar development of the cheek-bones, giving great breadth and flatness to the face, a broad cranium, with a low forehead, and often with the sides sloping away from the median sagittal tract, something like a roof ; whereas, in the liiuropean, there is combined, with greater capacity of the cranium, a more regular and beautiful oval form, a loftier and more expanded brow, a minor prominence of the malars, and a less projection of the upper and lower jaws. All these characteristics necessarily occasion slight differences in the facial angle. On a comparison of the basis cranii, the strictly bimanous characteristics in the position of the foramen magnum and occipital condyles, and of the zygomatic arches, are as well displayed in the lowest as io the highest varieties of the human species. With regard to the value to be assigned to the above defined distinctions of race : — in consequence of not any of these differ- ences being equivalent to those characteristics of the skeleton, or other parts of the frame, upon which specific differences are founded by naturalists in reference to the rest of the animal creation, the Professor came to the conclusion that man forms one species, and that these differences are but indicative of varieties. As to the number of these varieties : — from the very well marked and natural character of the species, just as in the case of the similarly natural and circumscribed class of birds, scarcely any two ethnologists agree as to number of the divisions, or as to the characters upon which those varieties are to be defined and circumscribed. In the sub- division of the class of birds, the ornithological systems vary from two orders to thirty orders ; so with man there are classifications of races varying from thirty to t^e three predominant ones which Blumenbach first clearly pointed out, — the Ethiopian, the Mon- golian, and the Caucasian or Indo-European. These varieties merge into one another by easy gradations. The Malay and the Polynesian link the Mongolian and the Indian varieties ; and the Indian is linked by the Esquimaux again to the Mongolian. The inhabitants of the Andaman Islands, New Caledonia, New Guinea, and Australia, in a minor degree seem to fill up the hiatus between .the Malay and the Ethiopian varieties ; and in no case can a well marked definite line be drawn between the physical characteristics of allied varieties, these merging more or less gradationally the one into the other. In considering the import and value of the osteological differ- ences between the gorilla — the most anthropoid of all known brutes -r-and man, in reference to the hypothesis of the origination of 38 Professor Owen on the [Feb. 9, species of animals by gradual transmutation of specific characters, and that in the ascending direction, Professor Owen admitted that the skeleton may be modified to a certain extent by the action of the muscles to which it is subservient, and that in domesticated races the size of the animal may be brought to deviate in both directions from the specific standard. By the development of the processes, ridges, and crests, and also by the general proportions of the bones themselves, especially those of the limbs, the human anatomist judges of the muscular power of the individual to whom a skeleton under comparison has appertained. The influence of muscular actions in the growth of bone is more strikingly displayed in the change of form which the cranium of the young carnivore or the sternum of the young bird undergoes in the progress to maturity ; not more so, however, than is manifested in the progress of the development of the cranium of the gorilla itself, which results in a change of character so great, as almost to be called a metamorphosis. In some of the races of the domestic dog, the tendency to the development of parietal and occipital cristae is lost, and the cranial dome continues smooth and round from one generation of the smaller spaniel, or dwarf pug, e. g. to another ; while, in the large deer- hound, those bony cristae are as strongly developed as in the wolf. Such modifications, however, are unaccompanied by any change in the connexions, that is, in the disposition of the sutures of the cranial bones ; they are due chiefly to arrests of development, to retention of more or less of the characters of immaturity : even the large proportional size of the brain in the smaller varieties of house-dog is in a great degree due to the rapid acquisition by the cerebral organ of its specific size, agreeably with the general law of its development, but which is attended in the varieties cited by an arrest of the general growth of the body, as well as of the particular developments of the skull in relation to the muscles of the jaws. No species of animal has been subject to such decisive experi- ments, continued through so maSiy generations, as to the influence of different degrees of exercise of the muscular system, difference in regard to food, association with man, and the concomitant stimulus to the development of intelligence, as the dog ; and no domestic animal manifests so great a range of variety in regard to general size, to the colour and character of the hair, and to the form of the head, as it is affected by different proportions of the cranium and face, and by the intermuscular crests superadded to the cranial parietes. Yet, under the extremest mask of variety so superinduced, the naturalist detects in the dental formula and in the construction of the cranium the unmistakeable generic and specific characters of the canis familiaris. This and every other analogy applicable to the present question justifies the conclusion that the range of variety allotted to the chimpanzee under the operation of external circum- 1855.] Anthropoid Apes J and their relations to Man. 39 stances favourable to its higher development would be restricted to differences of size, of colour, and other characters of the hair, and of the shape of the head, in so far as this is influenced by the arrest of general growth after the acquisition by the brain of its mature proportions, and by the development, or otherwise, of processes, crests, and ridges for the attachment of muscles. The most striking deviations from the form of the human cranium which that part presents in the great orangs and chimpanzees result from the latter acknowledged modifiable characters, and might be similarly produ- ced ; but not every deviation from the cranial structure of man, nor any of the important ones upon which the naturalist relies for the determination of the genera troglodytes and pithectis, have such an origin or dependent relation. The great chimpanzee, indeed, differs specifically from both the orang and man in one cranial character, which no difference of diet, habit, or muscular exertion can be conceived to affect. The prominent superorbital ridge, for example, is not the con- sequence or concomitant of muscular development ; there are no muscles attached to it that could have excited its growth. It is a characteristic of the cranium of the genus troglodytes from the time of birth to extreme old age ; by the prominent superorbital ridge, for example, the skull of the young chimpanzee with deciduous teeth may be distinguished at a glance from the skull of an orang at the same immature age ; the genus pithecus, Geoffr., being as well recognised by the absence, as the genus troglodytes is by the presence, of this character. We have no grounds, from observation or experiment, to believe the absence or the presence of a prominent superorbital ridge to be a modifiable character, or one to be gained or lost through the operations of external causes, inducing particular habits through successive generations of a species. It may be con- cluded, therefore, that such feeble indication of the superorbital ridge, aided by the expansion of the frontal sinuses, as exists in man^ is as much a specific peculiarity of the human skull, in the present comparison, as the exaggeration of this ridge is characteristic of the chimpanzees and its suppression of the orangs. The equable length of the human teeth, and the concomitant absence of any diastema or break in the series, and of any sexual difference in the development of particular teeth, are to be viewed by the light of actual knowledge, as being primitive and unalterable specific peculiarities of man. Teeth, at least such as consist of the ordinary dentine of mam- mals, are not organised so as to be influenced in their growth by the action of neighbouring muscles ; pressure upon their bony sockets may affect the direction of their growth after they are pro- truded, but not the specific proportions and forms of the crowns of teeth of limited and determinate growth. The crown of the great canine tooth of the male troglodytes gorilla began to be calcified when its diet was precisely the same as in the female, when both 40 Professor Owen on the [Feb. 9, sexes derived their sustenance from the mother's milk. Its growth proceeded and was almost completed before the sexual development had advanced so as to establish those differences of habits, of force, of muscular exercises, which afterwards characterise the two sexes. The whole crown of the great canine is, in fact, calcified before it cuts the gum or displaces its small deciduous predecessor ; the weapon is prepared prior to the development of the forces by which it is to be wielded ; it is therefore a structure fore-ordained, a predetermined character of the chimpanzee, by which it is made physically superior to man ; and one can as little conceive its development to be a result of external stimulus, or as being influ- enced by the muscular actions, as the development of the stomach, the testes, or the ovaria. The two external divergent fangs of the premolar teeth, and the slighter modifications of the crowns of the molars and pre- molars, appear likewise from the actual results of observation to be equally predetermined and non-modifiable characters. No known cause of change productive of varieties of mammalian species could operate in altering the size, the shape, or the con- nexions of the premaxillary bones, which so remarkably distinguish the great troglodytes gorilla, not from man only, but from all other anthropoid apes. We know as little the conditions which protract the period of the obliteration of the sutures of the premaxillary bones in the tr. gorilla beyond the period at which they disappear in the tr. niger, as we do those that cause them to disappear in man earlier than they do even in the smaller species of chimpanzee. There is not, in fact, any other character than those founded upon the developments of bone for the attachment of muscles, which is known to be subject to change through the operation of external causes ; nine-tenths, therefore, of the differences, especially those very striking ones manifested by the pelvis and pelvic extremities, which the Professor had cited in memoirs on the subject, published in the " Zoological Transactions,'* as distinguishing the great chimpanzee from the human species, must stand in contravention of the hypo- thesis of transmutation and progressive development, until the supporters of that hypothesis are enabled to adduce the facts and cases which demonstrate the conditions of the modifications of such characters. If the consideration of the cranial and dental characters of the troglodytes gorilla has led legitimately to the conclusion that it is specifically distinct from the troglodytes niger, the hiatus is still greater that divides it from the human species, between the extremes! varieties of which there is no osteological and dental distinction which can be compared to that manifested by the shorter pre- maxillaries and larger incisors of the troglodytes niger as compared with the tr. gorilla. The analogy which the establishment of the second and more formidable species of chimpanzee in Africa has brought to light 1 855.] Anthropoid Apes, a?id their relations to Man. 4 1 between the representation of the genus troglodytes in that continent, and that of the genus pithectis in the great islands of the Indian Archipelago, is very close and interesting. As the troglodytes gorilla parallels the pithecus Wurmbii, so the troglodytes niger parallels the pithecus morio, and an unexpected illustration has thus been gained of the soundness of the interpretation of the specific distinction of that smaller and more anthropoid orang. It is not without interest to observe, that as the generic forms of the quadrumana approach the himanous order, they are represented by fewer species. The gibbons {hylobates) scarcely number more than half-a-dozen species ; the orangs {pithecus) have but two species, or at most three ; the chimpanzees {troglodytes) are repre- sented by two species. The unity of the human species is demonstrated by the constancy of those osteological and dental characters to which the attention is more particularly directed in the investigation of the corresponding characters in the higher quadrumana. Man is the sole species of his genus, the sole representative of his order ; he has no nearer physical relations with the brute-kind than those which flow from the characters that link together the primary (unguiculate) division of the placental sub-class of mammalia. Professor Owen trusted that he had furnished the confutation of the notion of a transformation of the ape into man, which had been anticipated by the old author to whom he had referred at the outset, and strongly recommending his writings to those of his hearers who might not be acquainted with them, he concluded by quoting the passage referred to. " And of a truth, vile epicurism and sensuality will make the soul of man so degenerate and blind, tliat he will not only be con- tent to slide into brutish immorality, but please himself in this very opinion that he is a real brute already, an ape, satyre or baboon ; and that the best of men are no better, saving that civilizing of them and industrious education has made them appear in a more refined shape, and long inculcate precepts have been mistaken for connate principles of honesty and natural knowledge ; otherwise there be no indispensable grounds of religion and vertue, but what has hapned to be taken up by over-ruling custom. Which things, I dare say, are as easily confutable, as any conclusion in mathe- matics is demonstrable. But as many as are thus sottish, let them enjoy their own wildness and ignorance ; it is sufficient for a good man that he is conscious unto himself that he is more nobly de- scended, better bred and born, and more skilfully taught by the purged faculties of his own minde."* [R. O.] * Henry More's "Conjectura Cabbalistica," fol. (1662)— p. 175. 42 Mr, E, JekyU [Feb. 16, WEEKLY EVENING MEETING, Friday, February 16. Frederick Pollock, Esq. M.A. in the Chair. Edward Jekyll, Esq. M.R.I. On Siege Operations, The speaker, after a few preliminary observations, commenced by stating, that it is absolutely necessary for a besieging army thoroughly to invest the place about to be attacked ; that is, simultaneously to occupy positions so as to cut off all communica- tion with the threatened fortress, and to have a numerical force seven or eight times the number of the pent-up garrison. A reconnoissance is then made by the engineers, who, during the first part of the investment, are employed in taking notes of the description of the different fronts of the fortification, in making a correct plan of the work, and the ground in its vicinity ; in which the course of rivers, streams, ravines, and roads, the extent of possible inundations, woods, marshes, or eminences, are accurately laid down. They mark out, with great precision, by means of pickets, placed in the ground, the prolongation of all the faces of the most prominent works, and the salient angles as well : not only because the latter are the shortest road to the fortress, but because they are also the paths the least exposed to the enemy's fire. During this reconnoissance, the besieging army, having en- camped out of range of the guns of the place, send forth large working parties to cut down all the timber and brushwood in the neighbourhood, wherewith to construct the necessary materials for the siege. These consist of gun platforms, timber for the lining and support of mine shafts, galleries, and magazines ; but more particularly for the making of gabions, sap-rollers, and fascines. The gabion is a cylindrical basket of wicker work, open at both ends, and of various dimensions, but usually from three to four feet in height, and three feet in diameter. Its use and object being to construct hastily a shot-proof breastwork or parapet, when filled with earth, or to line the approaches and batteries when the soil is of a loose and crumbling nature. The sap-roller consists of two concentric gabions, placed one within the other, each six feet long, the interval between them being stuffed with logs of hard wood ; the whole mass far exceeding 1855.] on Siege Operations. 43 the dimensions of the ordinary gabion. It is employed to protect the sapper engaged at the head of an approach or trench, when advancing such work towards the enemy. T\\Q fascine is a faggot of brushwood, eighteen feet in length, and nine inches in diameter ; its use being to line the parapets, and various earthworks constructed during the progress of the siege. Bags filled with earth are also prepared, and largely employed during the operations ; the whole are then stored in that part of the camp called the Engineers' Park. The number of these materials is enormous, and the following estimate often has to be exceeded, or even doubled, namely, 80,000 gabions, 100,000 fascines, 120,000 sand bags, together with 4000 spades and shovels, and 3000 pick- axes, with other tools in like proportion. The enemy having been kept in ignorance of the front of the fortress about to be attacked, and all the necessary arrangements having been made, let us examine the object of the assailant, and the manner in which he may best proceed to effect it. His endeavour is to possess himself of a fortress ; and having seven or eight times as many troops as are shut up in the work, it follows that the larger number will overpower the weaker, if brought to a close combat ; but the battle-field of the foe is so organized as to prevent such collision, surrounded as it is by obstructions which the assailants must overcome : the besieger is, therefore, compelled to use both industrious and scientific means, in making his attack, requiring more or less time in their completion, in proportion to the defences of the place, its strength, and the courage of its protectors. The means employed since the invention of artillery, consist in choosing the front to be attacked, checking its fire, and in making a safe road by which the besieger can advance unseen to the foot of the ramparts ; and lastly, in placing in well protected batteries his artillery to subdue the place and effect a breach in the walls of the fortress. The first operation of the besieger is, to approach secretly by night with a working party of 1800 men, each carrying a fascine, pick-axe, and shovel, accompanied by an armed and protecting force equal to cope with the garrison ; the former dig a trench 2000 yards in length, parallel to the fortifications attacked, (the direction having been previously marked out by the engineers,) and with the earth excavated from such trench, raise a bank or breastwork on the side nearest to the enemy ; while the armed party, formed in a recumbent posture, remain in readiness to protect the workmen, should the garrison sally forth to attack them. During the night and follow- ing day the besiegers remain in the trench, till sufficient cover is gained to protect from the fire of the fortress all engaged, whether workmen or their appointed guard ; but as each fifty men have a certain task allotted to them, they are relieved by a like number at the expiration of their labour. 44 Mr. E Jekyll [Feb. 16, This work, called the Jirst parallel, is an envelope equi-distant from all the salient angles of the fortress, and it is along this road that all guns, men, and munitions can securely move, sheltered from the view and projectiles of the enemy. Batteries are then formed on the side next the place attacked, and a secure communication, made in like manner, is constructed towards the camp and entrepot of the besiegers. The garrison having now discovered the front of their work about to be attacked, do all in their power to add to their defences ; a double line of palisades is placed in the covered way ; traverses are erected to lessen the effect of the enfilade and ricochet fire of the besiegers ; the country on the side attacked is inundated, if such- means exist ; fresh embrasures are opened on the ramparts, and splinter proofs to prevent the ravages of shells are placed over the guns ; safe communications are formed, leading to the outworks ; mine galleries driven under the glacis (if none had been previously prepared,) and every means taken for repelling the advances of the besiegers. The fire from the guns, howitzers, and mortars of the assailants, is of a four-fold character : direct, to batter down such parts of the fortress as are not covered by the outworks ; enfilade, to rake ; ricochet, to bound down the faces of the ramparts, and dismount or otherwise injure the artillery ; and vertical, or that from mortars, to destroy the storehouses, magazines, barracks, or depots, within the walls of the place. After some days' fire, the same species of covered road is carried forward from the first parallel, by certain rules of art, to approach the fortress ; this trench proceeds in a zigzag direction, crossing and re-crossing the direct line leading to the salient angle of the fortress, care being taken that its direction is such, that no fire from the enemy can rake or enfilade it. And at a distance of 300 yards from the works of the besieged, a new place of arms, or second parallel, is constructed similar to the first, wherefrom the assailants can support the head of their attack. New batteries are here formed, to further enfilade the threatened works, and also to counter- batter such collateral works of the defenders as contribute to the defence of the place, and the fire of which it is necessary to subdue. The assailant again advances by similar zigzags, till within 150 yards of the covered way of the enemy, where fresh lodgments, called the demi-parallels, are effected. And here an entirely new feature in the attack presents itself : it being needful to keep down the heavy fire of riflemen, and wall pieces (heavy muskets fired from rests upon the parapets), and also to prevent workmen from repairing the injured defences, pierriers, or stone mortars, are placed in the wings of the aforesaid demi-parallels, which keep up an incessant discharge of large stones, 4-pound iron balls, and grenades, upon the front attacked. Volleys of such missiles are directed upon the shattered parapets, driving the defenders from the walls, and forcing them to fly to 1855.] on Siege Operations, 45 places of cover and security, protecting themselves from these projectiles by such temporary buildings as they can erect. The enemy in reply keep up a continuous fire from small mortars, called royals and coehorns, upon the head of the advancing trench ; light balls (a brilliantly burning firework), thrown by the garrison, disclose the operations of the enemy, who try to extinguish them with sand or wetted hides, and if such means fail, place smoke balls to obscure the light. The approaches are now carried forward by sapping, — a most hazardous duty. The foremost workman, protected by the sap- roller, pushed in front by a long fork, places a gabion on the side nearest the fortress ; he rapidly fills it with earth from the trench he is excavating (a labour he performs on his knees), digging the earth eighteen inches deep, and a like width, but never exposing himself beyond the first placed gabion. He is followed by three comrades, who increase the dimensions of the trench, and frequently relieve him in his perilous undertaking ; sand-bags are placed in the hollows between each gabion, and thus safe cover is effected ; ten feet of sap may be made in one hour. At the late siege of Antwerp, the French sappers were protected by helmets and cui- rasses, their weight however impeded the movements of the men ; and the celerity of the operation. At this period of the siege, the fire from the place being much weakened, many guns dismounted, and the ramparts ploughed up by the severity of the besiegers' fire, a third parallel is at length formed at the foot of the glacis, and an attempt made to gain the covered way, the palisades in which have been broken and de- stroyed by the ricochet batteries. If this is to be effected by assault, the interior of the breastwork of the third parallel is made in steps, so that the assailants may simultaneously sally forth to attain their object : but the slower and more certain method is by the sap and mine. At the siege of Cambray, Dumetz stormed a work during the attack contrary to the advice of Vauban, and sus- tained a defeat, together with a loss of 40 officers, and 400 men ; Vauban gained the same object two days later by sap, and lost but three lives. The covered way being now in possession of the besiegers, breach- ing batteries to destroy the revetments of the fortress are con- structed. The fire of six 24- pounders, so directed as to make perpendicular cuts in the masonry, play upon the wall : one long horizontal fissure three feet in depth is also effected, and by the firing in salvos or volleys, the loosened mass and superincumbent para- pet falls bodily into the ditch, presenting a slope or means of ascent more or less practicable. The troops are led to the assault by means of a subterraneous gallery leading from the trenches to the ditch. The garrison now usually capitulates. But if the latter part of the operations are carried on by the system of mining, the entire 46 Mr. E. Jekyll on Siege Operations. [Feb. 16, character of the attack is changed ; and as the besieger proceeds with the trenches on the surfjice of tiie ground he has to secure himself from below. Twelve days are added to the duration of the siege, if the fortress is ably protected by a well-arranged plan of defensive mines, in the more advanced galleries of which he can listen for the stroke of the miner's pick, and by means of a pea, placed upon a tightly-braced drum, subterraneous workmen can be dis- covered at the distance of from 60 to 90 feet in ordinary soil, hence such listening galleries, as they are termed, are built distant from each other 120 feet. When the advancing miner is discovered by the defenders of the fortress, a mine is hastily prepared, and the assailant blown to destruction. Occasionally a long iron probe is used, to ascertain the nature of the ground in front, or the position of the works of the besieged ; and if such instrument reaches into the defensive excavations it is followed on withdrawal by a charged rifle or musquetoon, and a shot is fired upon the assailant, or com- bustibles generating noxious gases are thrust into the aperture. The subject of mining is far too extensive a one to be embraced in so limited a description, but the globes of compression of the besiegers, or surcharged mines, finally overthrow the network of galleries with which the fortress is surrounded ; and the craters or hollows formed by their explosion, afford cover and the more ready means of pushing forward the saps and trenches, and the fortress is compelled to surrender. In describing the various en- gines of war, and the recent improvements made in them, Mr. Jekyll alluded to the making of cannon shot of a conoidal form, and the recently discovered danger of exposing live shells to the enemies' fire, both in batteries and on ship-board ; — shells struck by shot instantly explode, the blow raising the temperature of the stricken part far beyond the heat at which gunpowder inflames. Some of our first-rate men of war have their lower batteries of shell guns only ; and as each gun has two shells in boxes placed over each piece of ordnance, 64 mines are thus prepared for the destruction of the vessel, liable, during action, to add their ravages to those occasioned by the fire of the foe. In conclusion, comparison was drawn between the attack upon an ordinary pentagon, and the siege now in progress in the Crimea. In the former the prize was sure of being gained, inasmuch as the place was always previously invested, contained a garrison of but 5000 men, and was defended by 150 pieces of artillery, a portion only of which could be used in the defence of the single side attacked, a length seldom exceeding 320 yards ; the besiegers, with an over- whelming force of men and ordnance, having established themselves behind safe approaches, batteries, and a parallel or envelope embra- cing the fortress of a length of 2000 yards, finally ruined the defences of the fortress. At Sevastopol investment had been im- practicable ; the parallel of the allies, broken by the nature of the ground, was of no greater extent than 2300 yards, and the Rus- 1855.] Mr. Dickinson on the Supply of Water for London. 47 sian defences opposed a length little short of four miles, mounting 800 guns to the 500 of the combined armies, and aided by a gar- rison whose numbers were unknown and capable of continual augmentation. Screened from enfilade and ricochet fire by the nature and length of their works, and by the difficulty of placing the guns of the allies in favourable positions, the enemy could only be assailed by direct or vertical fire ; and the troops rushfng to the assault would have to advance to the attack over ground more or less open and unprotected, after leaving the shelter of their trenches. [E. J.] WEEKLY EVENING MEETING, Friday, February 23. The Rev. John Barlow, M.A. F.R.S. Vice-President and Secretary, in the Chair. John Dickinson, Esq. F.R.S. F.G.S. M.R.I. On providing an Additional Supply of Pure Water for London, Mr. Dickinson commenced by describing the two different modes of supply of water to towns, namely, the one by forcing it, by means of pumping engines, directly into the pipes of supply called mains ; the other by the delivery of it from a lake or reservoir on a high level, also through pipes ; in which latter case the water, by l^e mere force of gravity, will flow over large districts, and by the comparative difference of level will rise to the tops of houses below it, to which it is conveyed by the service pipes. He observed, that the supply by the New River Company com- prehended both those modes. The river flowed into a reservoir at Islington, called the New River Head, and, of course, mains, de- riving their supply from that, conveyed water to a large district of London situated below it ; but, furthermore, there were pumping engines at that spot, which forced up water to reservoirs at High- gate Hill and other places, from which it was supplied to districts situated above the level of the New River Head. He observed, that in speaking of a natural supply of water col- lected into a reservoir, at a high level, and delivered therefrom without the aid of pumping engines, the technical expression of engineers now is, " a supply by gravitation ; " and this is the mode adopted wherever opportunity offers ; which is more rare in 48 Mr. Dickinson [Feb. 23, England than in Scotland, because in the latter country, lakes, mountains producing rivers with sharp declivities, and tracts of moor land, adapted for gathering grounds, are to be found in the neighbourhood of their principal towns and cities, and the inhabit- ants have availed themselves of these local advantages for obtain- ing the supply needed ; and though, in some instances, they have had to convey water from considerable distances, and to form engineering works of great magnitude for receiving the water, yet they have to boast not only of the amplitude and excellence of their supply, but of its moderate cost. Mr. Thom, who gave evidence before the Commission, states, " At Campbeltown, a family of five individuals will be supplied for " about \s. 4d. per annum ; the cost at Ayr, for the same quantity, " is 2*. 2d. ; at Paisley, it is 25. 9c?. ; in Greenock, I think, it is " about 2s. 6d. I allow in this case 5 per cent, on the capital " employed ; the expense for wear and tear, charge for superintend- '^ ence, and the like, being always included in my estimate." He further states, " All those are high -pressure services, and reaching " the tops of houses, have all the advantages of being enabled to " put out fire, and supply the cisterns at the tops of houses." Mr. Dickinson remarked, that the supply by gravitation had the advantage of being constant instead of being intermittent ; and at the same time the works connected with it were more simple, and, by reason of saving the expense of steam engines, force-pipes, and coals, far less costly. He then proceeded to explain the mode by which it might be introduced, to a far greater extent than at present, for the supply of London, Westminster, and the western suburbs of the metropolis. The description of this was illustrated by maps, on a large scale, and a model, by means of which, and particularly by the model, the superficies of the country, and its geological features were exemplified, so as to render the description of the plan perfectly comprehensible. He explained that the model exhibited the valley of the river Lea, from whence the New River is derived, and that of the Colne, from which he proposed to derive another New River. He pointed out the uniformity of character of the rivers Lea and Colne ; that each of them was constituted by the confluence of several small perennial streams issuing from the deeper valleys of the chalk, which had their source towards the summit or escarpment of that stratum, and were fed and augmented throughout every yard of their course by springs. He explained, that in consequence of the absorbency of the sur- face, a considerable portion of the rainfall gradually descending through the crevices and fissures of the chalk, constitutes by its accumulation in those hills a vast natural reservoir, which, owing to the necessary difficulty of percolation towards the springs, main- tains a constant supply to the rivers throughout the year, though varying exceedingly in quantity according to the amount and period of the rainfall ; the summer rains being proved, according to a l8o5,] on providing Pure fValer for Londo?i, 49 system of experiment devised by Dr. Dalton,* to contribute almost nothing to the supply of this subterranean reservoir, in consequence of the great evaporation and the prodigious demands of vegetation during that period. f The speaker pointed out that either of these rivers, the Lea or the Colne, might be regarded as the outflow or yield of a large space of gathering ground, not less than 200 square miles ; and the Colne had this advantage over the Lea, that the valley through which it flowed to the Thames was in perpendicular elevation much superior to that of the Lea. " Mr, Dickinson then pointed out that it was only by very long and very definite experience in the actual measurement of the river, that any one could be convinced of the enormous fluctuation in the quantity of its flow, not only according to the season of the year, but between one year and another ; so that the late Mr. Telford, owing to the want of that experience, and to the neglect of seeking information from the best sources, had been led in his survey in 1834 to assume, that he could calculate upon a supply of 32 cubic feet per second from one, and that not the most considerable of the branches of the river Colne above referred to, which, at the present time, owing to the drought of last summer and autumn, does not yield mueh above one-third of that quantity. Mr. Dickinson gave it as his opinion, founded on more than forty years* experience, that by taking advantage of the whole supply of the valley, comprehending the four streams which are united at Rick- mansworth, viz. : — the Colne, the Ver (which was the choice of Mr. Telford), the Gade, and the Chess, which latter stream flows past Latimer and Chenies, a supply of 42 cubic feet per second could always be relied upon for London, besides leaving a surplus for the lower part of the valley, which would be aug- mented by the stream from Missenden, which joins the Colne below Harefield ; J and accordingly, he proposed to abstract 42 cubic feet per second at that point, for conveyance to London by a new aqueduct, constructed on more judicious principles than the New Hi ver of the Lea valley. A plan of this work, on a very large scale, was exhibited, and the speaker explained various novel contrivances by which he pro- posed to give space for the deposit of every thing of greater specific gravity than water, and to intercept every thing that would float, and to clear away scum, and guard the channel from leaves and vegetable refuse, also to aerate the water ; and, finally, to deliver twenty-three millions of gallons per diem — in other words, twenty- three gallons a piece daily, for a million of individuals — into a reservoir at Kilbum, so filtered, and at the same time so fresh, as to * See article " Evaporation," by Dr. Dalton, in " Rees's Cyclopedia." t See a vei'y ingenious course of experiments, published by Mr. Lawes, which shows that every plant of wheat, barley, and beans, takes up in the period of its growth 15lbs. of water from the soil, if the season will afford it. X The flow of water at that part, in a full season, index)endent of floods, is not less than four times that amount. Vol. IL e .lO Mr. Dickinson [Feb. 23, compare with the most perfect spring water, which reservoir, or head of distribution, would be 120 feet perpendicular above the datum line of the Ordnance Survey, made at the suggestion of the Board of Health.* The Ordnance map of London, the fruit of that survey, on the scale of 12 inches to the mile, with the elevation of every part of the metropolis stated upon it, was exhibited, which embraced also the reservoir ; and, by means of a line of uniform level traced upon the map, it was made apparent how very large a portion of London could be supplied by gravitation, at high-service level, over and above the whole of Westminster, Belgravia, Knightsbridge, Brompton, Chelsea, Fulham, and Kensington. Mr. Dickinson, having had a great deal of experience in works of this nature, was satisfied that the cost of delivering this quantity of water at Killjurn, purified and filtered, (presuming money to be obtainable at 4 per cent, per annum,) would not (according to Mr. Thom's mode of estimate) exceed three farthings per thousand gallons, including the very heavy item of compensation to mill-owners ; and that the whole cost of distribution would not exceed threepence per thousand gallons, which, as proved in the evidence of Mr. Hawksley, was the rate of charge for the water supply at Nottingham. Some of the water taken out of the river Colne, at Harefield, was produced at the meeting and much approved. With reference to the liability of the Colne being rendered turbid at the time of floods, (for at other times it is perfectly clear,) he quoted the following evidence of Mr. Hawksley on the subject of running water purifying itself, — " I can give a very extraordinary instance of " that, as occurring at Nottingham. At Nottingham the supply is " taken from the river Trent. Upon the tributaries of the river " Trent are situated the towns of Leicester, Loughborough, Derby, " Belton, and the whole of the Potteries. The water leaves those " towns frequently in an exceedingly black noisome state, but the " water of the river Trent is, nevertheless, exceedingly beautiful " and pellucid ; in fact, at Trent Bridge, near Nottingham, it is as " clear as crystal ; organic matter is not discoverable in it, except " in the degree in which it is discoverable in all river water." The speaker concluded by stating that he had taken particular notice of the amount of water expended in his own house and stables, (in Upper Brook Street,) and it led him to the conviction that the whole of the large and populous district, before referred to, southward of, and including Piccadilly, might be supplied by this application of the gravitation system at one-fourth the scale of the present rate of charge ; but with the proviso, that water for the streets and for public purposes, should be paid for out of the parish rates as at present. [J. D.] * This quantity is almost exactly double that of the New River, the total supply of which is stated by Mr. Mylne, the engineer of that Company, in his evidence before the Parliamentary Committee of Inquiry, respecting the water-supply of liondon, Qu. 8073, to be 11,872,000 gallons per diem. 1855.] on providing Pure Water for London. 51 March 2, 1855.] Dr, Stenhouse on Charcoal, 53 WEEKLY EVENING MEETING, Friday, March 2. William Robert Grove, Esq. Q.C. F.R.S. Vice-President, in the Chair. Dr. John Stenhouse, F.R.S. On tlie economical applications of Charcoal to Sanitary purposes. After describing the various ways in which both animal and vegetable charcoal are manufactured, Dr. Stenhouse stated, that the different kinds of charcoal most commonly in use may be con- veniently divided into three species, viz. wood, peat, and animal charcoal. The results of Saussure's experiments on the absorption of gases by boxwood charcoal were then exhibited in a tabular form. The speaker then described a series of experiments made by him to ascertain the comparative absorbent power of wood, peat, and animal charcoal for gaseous bodies. From these it appeared, that wood charcoal possesses a slightly higher absorbent power for ammoniacal, sulphuretted hydrogen, sulphurous acid, and carbonic acid gases than peat charcoal ; the absorbent powers of which, however, are immensely greater than those of animal charcoal. As a decolorizer, however, animal charcoal is greatly superior to either wood or peat charcoal. An account was next given of Mr. Turnbull's and Dr. Stenhouse's experiments, which consisted in burying the bodies of dogs and cats in charcoal powder, and in covering them over with about a couple of inches of the same material. No effluvia were ever perceptible, while the decomposition of the bodies was greatly accelerated. This arises from the circumstance that charcoal absorbs and oxidises the effluvia, which would under ordinary circumstances be evolved directly into the air ; but within the pores of the charcoal they are brought into contact with condensed oxygen, and are thus subjected to a species of low combustion, their carbon being converted into carbonic acid, and their hydrogen into water. Charcoal, therefore, so far from being an antiseptic, as was till recently universally believed, is, in fact, precisely the reverse. Dr. Stenhouse then stated that, from reflecting on the wonderful power of charcoal in absorbing effluvia and miasmata, as exhibited in the cases just described, where, as we have seen, all the putrid exhalations from the bodies of pretty large animals were absorbed and destroyed by a layer of charcoal powder little more than an inch in thickness, it struck him that a very thin layer of powdered 54 Dr. J. Stenhouse on the applications [March 2, charcoal would be equally eftectual in absorbing the very minute quantity of infectious matter floating in the atmosphere of what are called unhealthy situations. This led him to the construction of the so-called Charcoal Air-filter, first exhibited and described by him before the Society of Arts, on the 22nd of P'ebruary, 1854. It con- sists of a thin layer of charcoal powder, enclosed between two shee s of wire gauze. One of these air-filters, or charcoal ventilators, was erected more than three months ago in the justice-room, at the Mansion-house. This apartment, from the 'position of several nuisances in the very narrow street from which it is ventilated, was usually so offensive as to have become the subject of general complaint. Since the erection of the charcoal ventilator, through which all the air entering the apartment is made to pass, all the impurities are absorbed, and the atmosphere of the room has become unexceptionable. From the success attending on the char- coal ventilator at the Mansion-house, the City authorities have fitted up the justice-room at Guildhall with a similar apparatus, which is giving equal satisfaction. The charcoal ventilator at the Mansion- house has never required any alteration, such as renewal of the char- coal, or otherwise. Charcoal ventilators cannot fail to prove eminently useful in all situations where foul air is apt to accumulate, such as in water-closets, in the close wards of hospitals, in ships, and in the back courts and mews-lanes of large cities, all the im- purities being absorbed and retained by the charcoal, while a current of pure air alone is admitted into the neighbouring apartments. In this way pure air is obtained from exceedingly impure sources. A short sketch was then given of the history and construction of Eespirators, from their first proposal by Dr. Beddoes of Bristol, in 1802, till their description, some seventeen or eighteen years ago, by Dr. Arnott, in a lecture at the Royal Institution, and their being subsequently patented by Mr. Jeffreys, who first brought them into general use. Mr. Jeffreys' and the ordinary respirators are intended merely to warm the air ; but the charcoal respirators, especially those which embrace both the nostrils and mouth, purify the air by filtration, and thereby deprive it of the noxious miasmata which, in unhealthy situations, it not unfrequently contains. Experience has shown, however, that charcoal respirators not only purify the air, but warm it sufficiently, while they possess several advantages over the ordinary respirators. Thus, for instance, they are lighter and more easy of construction ; and where the breath is at all foetid, as is usually the case in diseases of the chest, throat, &c. the disagree- able effluvia are absorbed by the charcoal, so that pure air alone is inspired. The charcoal respirators are also exceedingly easy to breathe through, as, owing to the non-conducting nature of their material, they do not condense the moisture of the breath to an inconvenient extent. There are three forms of the charcoal re- spirator, one for the mouth alone, tlie others embracing both the mouth and nostrils ; these two latter forms being specially intended 1855.] of Charcoal to Sanitary purposes, 55 to guard the wearer against fevers, and other infectious diseases. Powdered charcoal has, during the last twelve months, been most successfully employed both at St. Mary's and St. Bartholomew's Hospitals, and in other similar establishments, to arrest the pro- gress of gangrene and other putrid sores. In the case of hospital gangrene we have to deal not only with effluvia but with real miasmata; for gangrenous sores not only affect the individual with whom the mischief has originated, but readily infect the healthy wounds of any persons in its vicinity. In this way gan- grene has been known to spread not only through one ward, but through all the wards of even a large hospital. This, and other instances which might easily be adduced, prove that charcoal is not only a deodorizer but a very efficient disinfectant. A great variety of other instances were mentioned, in which charcoal respirators would certainly prove exceedingly useful ; such, for instance, as to house-painters, the gunners in casemated batteries, persons requiring to traverse unhealthy districts within the tropics, such as the Delta of the Niger, the foot of the Himalaya, &c. Dr. Stenhouse concluded by stating it as his confident belief, that if our soldiers and sailors, when placed in unhealthy situations, were furnished with charcoal respirators, and if the floors of their tents, and the lower decks of ships were covered by a thin layer of freshly-burned wood charcoal, we would have little in future to apprehend from the ravages of cholera, yellow fever, and similar diseases. [J. S.] GENERAL MONTHLY MEETING, Monday, March 5. Frederick Pollock, Esq. M.A. in the Chair. J. Richard Andrews, Esq. John Baily, Esq. Q.C. Charles Beevor, Esq. F.R.C.S. Henry Bradbury, Esq. Henry Newnham Davis, Esq. J. Dickinson, Esq. F.R.S., G.S. John Viret Gooch, Esq. F.S.A. Rev. Geo. Delgarno Hill, M.A. Edward James, Esq. M.A.Q.C. Robert Lee, M.D. F.R.S. Walter M'Grigor, Esq. Leopold Redpath, Esq. were duly elected Members of the Royal Institution. George J. Lyons, Esq. Edmund Macrory, Esq. and John William Wrey, Esq. were admitted Members of the Royal Institution. 56 General Monthly Meeting. [March 5, The Secretary reported that the following Arrangements had been made for the Lectures after Easter : — Eight Lectures on Voltaic Electricity, by Professor Tyn- I)ALL, F.R.S. Eight Lectures (with Illustrations) on Christian Art, from THE Earliest Period to Raphael and Michael Angelo, by George Scharf, Jun. Esq. F.S.A. F.R.S.L. Eight Lectures on Electro-Physiology, by Dr. Du Bois- Reymond. The following Presents were announced, and the thanks of the Members returned for the same : — From Agricultural Societif of England, Royal — Journal. Vol. XV. Part2. 8vo. 1855. Asiatic Society r. Odlmg on the [March 16, with certain tlieoretical notions, these bodies liave been formulated as follows : — H-Cl HOH H*-0 (^Laurent.) HNIP IP-NH IFN {Kane) (.Wurtz.) HCIP IP-CH* IP-CH iLieUg.) (^Dumm.') (^OdUng.-) Coal-gas may be represented as terhydride of formyl, analogous to its derivative chloroform, or terchloride of formyl. The two bodies can be prepared in virtue of analogous equations from acetic and chlor-acetic acids respectively, and the one can be obtained from the other by direct substitution. Each of the above theories has certain circumstances in its favour ; each is true to a certain extent ; each represents the body in question from a different point of view ; sometimes one point of view is most advantageous, sometimes another. As a veritable representation of the constitution of coal-gas, Dumas' view is pre- ferable to either of the other two theoretical views. The adoption of Laurent's sarcastic suggestion of peroxide of hydrogen as a compound radical, leads to inadmissible or uncertain results ; thus, is potash oxide of zinc K Z O a combination of a hypothetical peroxide of potassium with zinc, or of a hypothetical peroxide of zinc with potassium ? Is Williamson's double ether, Me ¥A O, a combination of peroxide of methyl with ethyl, or of peroxide of ethyl with methyl ? &c. Nevertheless, there are greater grounds for recognising peroxide of hydrogen as a compound radical, than there are for recognising ethyl and methyl as such. A large number of bodies may be represented very feasibly as containing ethyl ; but an infinitely larger and more varied set of bodies may be represented as con- taining peroxide of hydrogen : such, for instance, are water, potash, sulphuric acid, formic acid, benzoic acid, hypochlorous acid, &c. &c. and, as has been shown by Mr. Brodie, very many other more com- plicated bodies. Many equations may be represented very simply by means of ethyl analogous to hydrogen ; but a much greater number may be represented by means of peroxide of hydrogen analogous to chlorine. Ethyl has been obtained in the free state, so has peroxide of hydrogen ; but whereas nearly all the bodies of the peroxide of hydrogen series can be obtained directly from it, not one single ethylic combination has ever yet been obtained from ethyl. Hydrogen and ethyl present certain analogies, but the analogies of chlorine and peroxide of hydrogen are much more complete. Both bodies bleach, oxidise, combine directly with potassium, set free bromine and iodine, and take the place of the bromine and iodine set free. In Ba-QH and in Ba CI the Ba 1855.] Constitution of the Hydro-carbons. 65 can be readily detected ; but with regard to H CI and Et CI, the CI can be detected in the former only. All the facts connected with the mutual relations of C* H* — ethylene, or olefiant gas C*H*0 -aldehyd C*H*0*— acetic acid C* H" — hydro-ethylene C* H* CI — muriatic ether C* H« O —alcohol, especially since the recent researches of Berthelot, show the superi- ority of Dumas' ethylene to Liebig's ethyl theory, both as regards its more complete accordance with experiment, and its greater generality. The probabilities in favour of the pre-existence of C* H* and its derivatives, as constituent groups, are much greater than are those in favour of the pre-existence of C* H*. Thus, with regard to ethylene, hydro-ethylene, muriatic ether, and their chlorine deriva- tives, we ought to have the following series, convertible into one another through certain members : — C*H* -H^ C^H* -HCl C* IP CI -IP C*IP C"H* -CP C*H«C1 -HCl C^IPCP-IP C* H» CI C*H«C1 -CP Cni^CP-HCl C*H CP-IP C*H«CP C^IPCP CP C'H CP-HCl C^ CY'W C*H CP C^HCP-CP C' CPHCl C* CI* C* CPCP Of these four series, three are undoubtedly, and the fourth most probably, known to us. They illustrate rationally the nature of the isomerism. In the three latter series, we have every reason to believe, that, with regard to the carbon, two of the hydrogen or chlorine atoms stand in a different relation to the other four ; but in the first series, we have not a single fact tending to show, that one of the hydrogen atoms stands in a different relation to the other three ; not one fact to countenance the representation of olefiant-gas by C* H«'H, hydruret of acetyl. In the next best known hydro-carbon, namely, benzine, there is no more reason for believing in the existence of the monobasic radical phenyl C* H', than there is for believing in the bibasic and tribasic radicals C H* and C* H^, respectively, as seen in the following table :— (X = NO* Ad = NH') C'W' H C«H*' W C«H^' W C'H»' CI C«H*- Ad« C«H«" CP C«H»" Br C«H*- X* C«H»' Br« Ceijs. Ad C«H*- X Ad C«H»' Ad»X C'W- X C«H*- CI Ad C'H'- X«Ad C" IP • Br Ad, &c. Q*W' X* CI, &c. F 2 66 Rev, J. E. Ashhy [March 23, Lastly, Willianison's othyl theory, although it possesses a great degree of generality, and is supported by most complete analogies both in mineral and in organic chemistry, is only one of many ways of indicating the mutual relations of bodies. It must not be taken as the sole veritable representation of the constitution of the com- pounds to which it applies. There are no greater proofs of the pre-existence of othyl in acetic acid, than there are of the pre- existence of peroxide of hydrogen in water. For example, the correlations of benzamide, benzonitryl, hydro- benzamide, and dibenzoylimide, are entirely neglected in the othyl theory. These bodies belong to one single class ; they all contain certain benzoic elements, and certain ammoniacal elements ; by the absorption of water they yield ammonia, and benzoic acid or alde- -hyd. But the othyl theory bears no reference to this point of view ; it separates benzamide widely from its congeners. Thus we are told that the first body contains the compound radicals benzoyl (analogous to othyl) and amidogen ; the second, the compound radicals phenyl and cyanogen ; the third, nitrogen and the com- pound radical benzyl (analogous to acetyl), whilst, with regard to the fourth, as to many other bodies, the compound radical theory fails altogether. In the three best known hydro-carbons, coal-gas, olefiant-gas, and benzine, as in many other bodies ordinarily represented as contain- ing compound radicals, the conception of self-existent constituent compound radicals, is not only unnecessary but irrational. The particular groupings of atoms, which we denominate compound radicals, do not have an existence apart from the other constituents of the bodies, into which they are said to enter. [W. 0.] WEEKLY EVENING MEETING, Friday, March 23. Henry Bence Jones, M.D. F.R.S. in the Chair. Rev. John Eyre Ashby, On {so-called) Catalytic action and Combustion; and theories of Catalysis. The study of Catalysis is a study of forces. It comprehends the conditions under which force is exerted in a peculiar manner in chemical decompositions and combinations, and of the nature of the force only as compared with forces at work in chemical changes, 1855.] on Catalytic Action and Combustion. 67 which are commonly thought to be better understood. The precise meaning of the word should not be derived from its etymological constitution, nor even solely from its original application, but rather from the general consent of eminent chemists as exhibited in their published writings. The term has been employed very loosely, and some of the definitions given do not allow of reduction to a common statement. Adopting the principle laid down, catalysis may be defined as the action by contact of one substance upon another substance, or group of substances, whereby chemical changes are effected, while the first substance remains finally un- changed. This will exclude from catalysis the following cases : — 1 . The operating body does change, although it does not com- bine. Examples. — Fermentation, as explained by Liebig. Solution of an alloy of platinum and silver in nitric acid ; also of the alloy of copper, zinc, and nickel, in dilute sulphuric acid. 2. The operating body absorbs A from a combination (A + B), and B cannot exist free. Example. — Crystallized oxalic acid is a combination of anhydrous oxalic acid and water ; if cast into strong sulphuric acid, the water is absorbed, and (so far as we know at present) taken into chemical union with the sulphuric acid ; but the anhydrous oxalic acid cannot exist free, and is resolved into equal volumes of carbonic acid and carbonic oxide, which escape accordingly. 3. The operating body takes from a substance some of its elements, and combines with them after they have combined with each other. Example. — Sulphuric acid in contact with sugar, takes the elements of water from the carbon, and combines with them by hydration. 4. The operating body causes mutual changes in substances A and B, whereby they become other substances, say C and D, and the operating body combines with D. Example. — Hydrocyanic acid and water + hydrochloric acid (the operating body) gives formic acid and ammonia, of which the ammonia combines with the hydrochloric acid. C«NH + 3H0 becomes NH3+C2HO3 and we have N H, CI + Ca H O3. Cases of chemical change by friction and percussion are excluded, because contact is mechanically statical, whereas these are dynamical in respect of the masses. A lucifer match is an example. Sir James Kane, however, supposes the decomposition of iodide of nitrogen by slight percussion to be catalytic ; his definition is made wide enough to take it in. 68 Reo. J. E. Aahby [March 23, The definition given by the speaker as being, upon the whole, in harmony with the prevailing ideas of catalysis, will be found to include the following cases : — 1. Galvanic action in relation to a finally unchanged platinode. In every battery-cell containing an apparently unchangeable plati- node, all the conditions of catalysis are perfectly fulfilled when the platinode touches the zincode without the intervention of any other metallic conductor ; and the truthfulness of the fulfilment is not altered by the additional fact that similar action will ensue when a metallic (or other) conductor is interposed. It is very doubtful whether the platinode really undergoes no changes, but it remains unchanged at last. 2. A finally unchanged body produces in certain others no decomposition, but only combination. Example. — Platinum combines hydrogen and oxygen into water. 3. A finally unchanged body produces decomposition, but no re-combination. Example. — Decomposition of chlorate of potash by metallic oxides and heat. 4. A finally unchanged body produces decomposition, and partial or total recomposition, of the elements of a body. Example. — Alcohol passed into sulphuric acid at 300" passes out as ether and water, the elements of water having been ab- stracted by the acid, which cannot retain them at that temperature. If we suppose that the acid removes water, as such, from the alcohol, this case is resolved into the foregoing. 5. A finally unchanged body produces the decomposition of another substance, and causes some of its elements to enter into combination with a third body, also present. Examples. — Heated platinum decomposes alcohol vapour, with access of air. In illustration of this class of phenomena, the speaker exhibited the continuous combustion of the vapour of strong liquid ammonia by a fiat spiral of platinum wire (y^^^ inch thick) evolving nitrous gas and water. Mr. Ashby then briefly adverted to the principal theories of Catalysis. 1. Berzelius, who introduced the term into chemistry, considers that it represents a new force. 2. Liebig dwells at great length upon cases in which the opera- ting body does not remain finally unchanged. He supposes that if A and B are in contact, and changes happen among the particles of A, these may induce changes among the particles of B, by destroy- ing the statical condition, and forcing the particles into motion, whereupon they arrange themselves into new groups. This does not explain at all the cases included under the definition given in this dis- 1855.] on Catalytic Action and Combustion. 69 course. It is just possible that it may ultimately prove to be a truth in relation to those cases, but it does not, at present, explain them. 3. Playfair observes, " There are many instances where catalytic decompositions ensue, where there is no intestine motion in the atoms of the exciting body. Hence we cannot do more than consider motion as favourable to the development of dormant affinities." He should, perhaps, have said, "Where there is no apparent intestine motion ;" and there may be an undesirable am- biguity in the phrase, " favourable to the development of dormant affinities." In his essay on the subject, (a monument of learning and industry,) he concludes, that " the catalytic body is a substance which acts by adding its own affinity to that of another body, or by exerting an attraction sufficient to effect decomposition under certain circumstances, without being powerful enough to overcome new conditions, such as elasticity and cohesion, which occasionally intervene, and alter the expected result." (Thus, for instance, A and B have each separately an affinity for the element (e) of a third body E, but neitlier, separately, can tear it from its combina- tion with E : — the joint attraction of A and B mai/ be sufficient to release it ; but the released element will not therefore necessarily combine with A and B.) 4. Faraday, and others, consider that many cases of catalysis are due to the powerful condensation of liquids, vapours, and gases, upon the surface of the catalyzing body. This view is of great importance, but not (as yet) equal to the explanation of nearly all the phenomena. Some of the arguments in favour of it may be found in a consideration of the probable mechanical condition of platinum, owing to the method of manufacture, the ascertained absorptive power of certain catalyzing agents, and the probable condensation of water in sulphuric acid. 5. De la Rive explains the particular case of the combination of hydrogen and oxygen on the surface of platinum, by supposing that the platinum is oxidated on its surface, and the oxide con- tinuously reduced by the hydrogen, water resulting. (See Gmelin's Chemistry, published by the Cavendish Society, Vol. II. p. 56.) Mr. Ashby then described his own researches on catalytic com- bustion. If the sesquioxides of chromium, nickel, cobalt, manga- nese, and iron, be laid upon wire-gauze (about 60 meshes to the inch-linear,) then warmed in the flame of a spirit-lamp, and laid over capsules nearly full of alcohol, pyroxylic spirit, ether, or other similar substances, they will burst into glow and catalyze the vapours which rise into them, as long as the supply continues- Warm Cr^ O3 will inflame a jet of hydrogen in contact with air. The sesqui- oxide of iron is peculiarly available for operations on any scale, however large, and those specimens are to be preferred which have the least density. A catalytic lamp was exhibited, by which spirit or benzole may be consumed by the catalytic glow for laboratory 70 Rev. J. E. Ashby [March 23, purposes. Coal-gas mixed with air may also be employed under the gauze upon which the oxide is distributed. Euchrome (dug from the estate .^of Lord Audley) is a cheap and useful catalyzing agent, when freed from its carbon.* A mixture of ten parts by weight of chlorate of potash, with one part of light and finely divided sesquioxide of iron, yields oxygen with entireness and facility, and has the additional advantage that {n) grains of the mixture represent very nearly {n) cubic inches of evolved oxygen. If we take the case of the sesquioxide of iron, we are able, to some extent, to show the modus operandi of the catalytic action ; we can arrest the process at the half-stage, and then at leisure complete the other half. By heating Feg O3 to redness, and quenching it in boiling alcohol (air being excluded), or by passing the vapour of alcohol over heated sesquioxide, we obtain two results ; the alcohol is oxidated, and the Fcg O3 becomes Fcg O4 by deoxidation. The same follows by treating the sesquioxide with ammonia, gaseous or in strong solution. This black magnetic oxide (probably Fcg O4 + H O) remains unchanged by a red heat, if oxygen be not present ; but if warmed in contact with air, it absorbs oxygen at a temperature far below redness, and returns into the original Fcg O3. It is clear, then, that during the catalysis, an intestine motion of the particles is going forward, and every portion of the sesquioxide is constantly reduced by the alcohol and reoxidated from the air. This was il- lustrated by a diagram and a cluster of coloured balls. Attention was then drawn to a singular fact, which may probably be referable to the catalytic action of the sesquioxide of iron. If the ferro- cyanide of barium be heated until it ceases to give off ammonia, and then placed over alcohol, ammonia is again evolved in small quantity ; but if the same experiment be tried with pure prussian blue, a large quantity of ammonia is formed by the contact with alcoholic vapour. Alumina (AI2 O3) presents a singular pheno- menon, hitherto unobserved ; a pure specimen, of snowy whiteness, on being heated to redness, and exposed to the vapour of alcohol, becomes dark-grey, or black, and the vapour is oxidated ; and this effect may be produced (with less ease) by ammonia. It seems that the sesquioxide of alumina has become a lower oxide, as in the case of iron, but cannot recover oxygen from contact with that gas. INIr. Ashby then exhibited a " galvanic indicator,'* by which he hopes to prove satisfactorily, whether or not a galvanic current is set in motion during catalytic combustion. In conclusion, he drew attention to several points of interest connected with catalysis. * Mr. Arthur Church has observed that several of the chromates (copper, manganese, cobalt, &c.) after ignition, will freely catalyze alcoholic and other vapours. 1855.] on Catalytic Action and Comhmtion. 71 1. The value of catalytic processes in various manufactures. Nitric oxide acts catalytically in the preparation of sulphuric acid of commerce ; spongy platinum has been employ^^ for the same purpose ; and a patent has lately been granted for a similar use of the sesquioxide of iron. Spongy platinum is sometimes employed in Germany for the preparation of acetic acid from alcohol. The manufacture of ether from alcohol by sulphuric acid has already been noticed. 2. Considering that catalytic combustion by the sesquioxide of iron is first set up at a temperature far below redness, — that even a rusted nail may be sufficiently active, — and that in many cases of fermentation inflammable vapours may be disengaged, and much heat evolved, — it is not unreasonable to suppose that in this way we may account for some instances of what is commonly called " spontaneous combustion." 3. There is much reason to suppose that catalysis plays a great part in the organic chemistry of nature, in relation to vegetable and animal life. The experiments of Mr. Turnbull and Dr. Sten- house point to catalysis as a vast sanitary agent. The dead bodies of various animals were covered with a layer of charcoal, which rather assisted decomposition than otherwise, serving as a carrier to the oxygen of the atmosphere, and delivering the perfectly innoxious and inodorous products of catalytic combustion into the air, while the charcoal itself remained entire and unconsumed. If we bear in mind (as established by Mulder and others) that humus has the same property, and that many oxides in the mould are catalytic in a greater or less degree, it becomes evident that interment under- ground may bring into play a catalytic process by which the elements of an organic body are returned into the atmosphere in forms which are not prejudicial to existing life. 4. Since some oxides exhibit a tendency to promote catalytic combustion, which are at present thought to be the only oxides of those bases, and in the case of one oxide (iron) the process has been shown to consist of alternate reduction to a lower oxide, and re- oxidation, — it is quite possible that further research may lead to the discovery of some new oxides. [J. E. A.] 72 Rev. J. Barlow on the application [March 30, WEEKLY EVENING MEETING, Friday, March 30. William Kobert Grove, Esq. Q.C. F.R.S. Vice-President, in the Chair. The Rev. John Barlow, M.A. F.R.S. Vice-President and Secretary R.I. On the application of Chemistry to the Preservation of Food. Neither force nor matter has been added to or taken from the natural world since the commencement of its present condition — consequently the development and growth of successive races of plants and animals are dependent on the supply of materials which once formed part of the structure of their predecessors. Needful, however, as is the decomposition of the dead to the continuance of universal life over the globe, it is equally necessary to the main- tenance of civilized life, that this law should be modified. Man has been, accordingly, permitted to acquaint himself with the conditions of destruction so far as to become able to suspend its process. These conditions appear to be — 1. A temperature above 32"^ Fah. 2. The presence of air and moisture. 3. A peculiar (generally liquid) condition of that albuminous substance which surrounds the cells and fibres of all animal and vegetable structures. 1. Decomposition will not occur at the temperature of freezing water. We believe that long before this planet was inhabited by any creature of intelligence capable of receiving the idea of time, bodies of animals, which became extinct before man existed, re- mained undecomposed, because they were imbedded in ice, or in frozen earth.* Meat and fish are transmitted from Archangel for sale at St. Petersburg. Provisions are also sent packed in ice from remote parts of Britain to London. The use of ice-houses and ice-chests for the preservation of food, is among many obvious applications of this principle. 2. Decomposition will not occur, if moisture be excluded. * Pallas's Travels, quoted by Sir C. Lyell ; " Principles of Geology, 8th Ed., p. 82. 1855.] of Chemiatry to the Preservation of Food. 73 The decomposing property of the oxygen of the air is most efficient where water is present in a state of minute subdivision. In this case the water (even if it does not promote corruption by itself becoming decomposed,) absorbs from the atmosphere oxygen, which it presents to the decomposable body in a state the most effective for its destruction. " Kain-water, and especially dew, will bring on the putrefaction of animal matters much sooner than spring- water ; and the vulgar prejudice respecting the effect of the moon's rays in accelerating the corruption of meat, is, no doubt, dependent on the fact, that during clear moonlight nights, there is always a large deposition of dew ; and this, having fallen in a minutely divided state, possesses the largest amount of free oxygen which pure or distilled water is capable of absorbing from the atmosphere ; and therefore has a proportionate power of decomposing — just as it also has of bleaching." * An interesting illustration of the respective effects of a dry and a moist atmosphere occurs in Sir F. B. Head's " Rough Notes.'* Sir Francis, contrasting the atmosphere of Mendoza, St. Lucie, and Buenos Ayres, (all being in the same latitude,) states that in the two former provinces, " The *air is extremely dry : there is no dew at night, and the dead animals lie in the plain dried up in their skins, so that occasionally I have at first been scarcely able to determine whether they were alive or dead :" but in the province of Buenos Ayres, on sleeping out at night — " I have found my poncho, or rug, nearly wet through with dew ; the dead animals in the plain are in a rapid state of putrefaction/'j" 3. Decomposition of a moist organic body may be prevented if air be entirely excluded. " Gay-Lussac found that when bruised grapes were carefully excluded from the air, no change ensued ; but that even a momentary exposure of the pulp to air or oxygen was sufficient to communicate to it the power of fermentation. "{ — A bottle was exhibited, containing a piece of meat and a stick of phosphorus. They had remained together since January 15, 1855. The meat appeared fresh, but the phosphorus was visibly oxidized and acidified. Application of these principles to the Preservation OF Food. A. Principle of desiccation at a temperature below that which would cause the albumen to coagulate. Animal and vegetable substances dried in the sun, or at a low * On Preserved Meats for the Naval Service. — Newton's London Journal, Vol. xl. p. 200. t " Rough Notes," &c. 2nd FaI. p. 8. Vide also on same subject, p. 142. Also Murray's " Handbook for Travellers on the Continent." Gth Ed., p. 268, on the preservation of the bodies of the monks at Kreuzberg. t " Brande's Manual," Vol. ii. p. 1640. Gth Ed. 74 Rev. J. Barlow on the application [March 30, artificial heat, are less prone to decompose, even though they be not isolated from atmospheric air and moisture. Hay and dried fruits are obvious examples of the application of this principle. B. Principle of isolation from atmospheric influences^ the albu- minous constituent remaining uncoagulated. An expedient for protecting meat on this principle has recently been carried out on a large scale at Paris. It is described at length in the AssemhUe Nationale of the 23rd of January (quoted in the Siecle of the 22nd of February). The flesh is immersed in a gelatinous solution, which, when dry, forms an air-tight integument. It is named by the inventor " vernis cristallise," and is said to make an excellent soup. — Joints of meat, both raw and fresh, and eggs, which had been prepared five months before by this process, were exhibited by Mr. M. Rennie : all appeared in good condition.* If meat be coated with dry wheaten flour, the time that it will continue sweet may be prolonged threefold in tropical climates. The flour probably acts as an isolator against air and moisture. The preservation of organic substances in glycerine, oil, and syrup, and the more familiar process of salting,! probably derive their efficacy from the principle of isolation. J But, although brine effectually protects the meat which it sur- rounds against atmospheric oxygen, " flesh by salting loses in point of nutritive value, in consequence of the removal and division of the salts indispensable to sanguification. "§ This was illustrated by experiments on brine, which was obtained from a piece of beef salted in the course of the day, and proved to contain albumen, phosphoric acid, lime, and iron. The following preparations made with glycerine, were exhibited — (a) A small piece of flesh which had been partially immersed since February 20, 1855, in a bottle containing a small quantity of glycerine. By daily agitating this bottle, that part of the flesh which rose above the surface of the fluid was kept moist. {b) In each of two jars of glycerine about 4 lbs. of meat were * The specimen of raw flesh thus prepared had shrunk, as if the " vernis cristallise " had acted as the skin of a grape when it becomes a raisin ; i.e. it had permitted the escape of constituent moisture, but had prevented the admission of atmospheric moisture. t On April 23rd, 1841, Mr. Macilwain gave an evening discourse on Payne's mode of salting, by subjecting the substance to atmospheric pressure. — Literary Gazette, for 1841, p. 280. Repertory of Patent Inventions, Vol. xvii. p. 168.' X It was shown, by placing vessels of glycerine and strong brine under the exhausted receiver, that the latter is almost entirely, the former absolutely, free from dissolved air. § Liebig's " Familiar Letters," p. 430. 3rd Ed. II It has been suggested, that the sensation of thirst, experienced after eating salt meat, may, in some degree, be owing to the tendency of a saline solution to dry up animal membranes. 1855.] of Chemistry to the Preservation of Food. 75 sunk by weights below the level of the fluid. This preparation was made on the 20th of February, 1845.* In all these vessels the meat was fresh and sweet. The gly- cerine, however, like the brine, was reddened, indicating the separation of colouring matter, and therefore of iron, from the flesh immersed. The surface of the glycerine in the larger jars was studded with patches of mould. It was therefore inferred that some of the organic constituents of the meat, either singly or in combination, had been also separated ; but that, owing to the impermeability of glycerine by air, tlie decomposition did not take place beneath the surface of the liquid. In concluding this part of his subject, Mr. Barlow remarked, that one decomposition was sometimes had recourse to for the purpose of preventing another, as when wood, &c. is preserved by being painted over. The liquid paint is converted, by the action of the atmosphere, into a kind of solid, impermeable, insoluble soap. The stereochrome of Fuchs is another instance of this protective de- composition. There, however, tlie protection is derived from the combination of a portion of the protecting body with a part of that which it is intended to preserve.^ C. Organic Substances protected by a Change effected IN THEIR Albuminous Constituents. This is accomplished (1.) By chemical reagents. (2.) By heat and desiccation. (1.) Coagulation of albumen, by chemical reagents. The preservation of timber, by corrosive sublimate, was fully described by Dr. Faraday, in a Friday evening discourse, in ] 833, on the prevention of dry-rot, when it was proved that this salt formed a stable compound with the albuminous matter of the wood. On March 7, 1845, Mr. Goadby discoursed "on the nature and action of preserving fluids, as applied to animal structure."J This process consisted in the use of a solution of salt, with a small addition of corrosive sublimate. § In illustration of this mode of preservation, Mr. Barlow exhibited specimens of flesh which had * The glycerine used in one of these two jars was prepared according to Tilghman's process, by the action of water at a high temperature. Newton's London Journal, Vol. xlv. p. 343. The glycerine contained in the other jar was obtained by the decomposition of a fatty body by steam, as described by George Wilson, Esq. Proceedings of Royal Society, Vol. vii, p. 182. t Vide Proceedings of the Royal Institution, April 7, 1854. Vol. I., p. 424. (Rev. J. Barlow on Silica). X Vide Athenaum for 1845, p. 272. § Vide Admiralty Manual of Scientific Enquiry, edited by Sir J. Herschel ; article Zoology, by Professor Owen, p. 357 ; and " Directions for Preserving Specimens of Natural History," published by the Smithsonian Institute, Wash- ington, U.S. 1854. 76 Hev, J. Barlow on the application [March 30, been immersed since December 1st, 1854, in alcohol, in pyroxy- lic spirit, and in fusel-oil, as well as other similar specimens, which had been suspended, for an equal period of time, in the vapours of the same liquids. The antiseptic effects of creosote, the active principle of wood-smoke, (which is almost the only substance whose chemical reaction on the albuminous constituent of organic matter is employed for the preservation of food,) were then noticed. (2.) Coagulation of the albuminous constituent bi/ heat. The identity of the antiseptic effect of heat with that of a strongly coagulating reagent, as corrosive sublimate, was shown by exhibiting — (a) Two pieces of flesh, one of which had been thoroughly cooked and dried, and the other washed over with a solution of sublimate. Both had been kept dry : the surface of both was hard and dark, (b) Two similar pieces of flesh, similarly pre- pared, but exposed to a damp atmosphere : both were in a mouldy, but neither of them in a putrescent condition. Dr. Verdeil has applied the coagulating effect of heat to the pre- servation of vegetables and of meat. He directs that green {i. e, unripe) vegetables, such as cabbages, carrots, green peas, French beans, should be submitted to the action of high-pressure steam of the temperature of about 300° Fah., and then dried as quickly as possible. Specimens of vegetables prepared by this process were exhibited. Although kept in paper envelopes they appeared to have suffered no change from the effect of air. The aromatic oils being retained in the coagulated albumen, imparted its characteristic flavour to the cooked vegetable, which, retaining the minutest details of its structure, resumed its original form and size on being steeped in water.* The sanje principle has been applied by Dr. Yerdeil to the pre- servation of meat. Edwards's potatoes, belonging to the same class of preparations, claim notice from the rapidity and facility with which they can be dressed. D. The Principle of Coagulation of Albumen by Heat, BUT WITHOUT DESICCATION, THE PROVISIONS BEING ISOLATED FROM AlR AND EXTERNAL MoiSTURE. This seems to be the principle of the well-known processes both of Appert and of Goldner. The former aims at the combination of whatever oxygen may be present in the vessel containing the pre- * This was illustrated by the expansion of a cauliflower, an artichoke, and of Brussels sprouts, and by the odour and flavour of carrots, turnips, onions, &c. all prepared by Dr. Verdeil, which were cooked during the evening in the presence of the Members and visitors. 1855.] of Chemistry to the Preservation of Food. 77 served provisions, with some of the organic matter ; and the latter, at exclusion of that oxygen by the action of steam. A canister of rice and meat, prepared by Appert, which had been in the possession of Messrs. Fortnum and Mason* for ten years, was opened under a saturated solution of salt ; the air it contained was collected in the usual way, and when tried by the nitric-oxide (NO*) test, was found free from oxygen. Bottles of choice fruit and green vegetables, in excellent condition, were exhibited ; these had been prepared five or six years since by Appert's process. M. Appert kindly sent from Paris for exhibition on this evening a case of beef and soup, 3000 kilogrammes of which he is now daily preparing for the French army in the Crimea. M. Appert also exhibited specimens of more luxurious delicacies, as cr6me au chocolat, pate de foies gras, pate de canard. The same process has been adopted and developed in this country, with eminent integrity and success, by Mr. Gamble, who has succeeded in preserving not only the substantial materials of' food, but also fish and other luxuries of the table.f Two large tin canisters'of dressed meat, which had been prepared by Goldner's process (expulsion of air by steam) in the year 1840, in the presence of Dr. Faraday and Professor Graham, were ex- hibited. As neither of these canisters had bulged out, it was inferred that no gas had been formed, and that therefore no de- composition of their contents had taken place. E. Preservation of Milk. Four processes of preserving milk were noticed ; each depended on a different principle. 1. The process of M. 3Iahru. This process preserves milk without addition of any substance whatever. It consists essentially in the exposure of metallic bot- tles, each containing about a quart of milk, to steam raised to the temperature of 212^ Fah. These bottles are fitted with leaden tubes, by means of which they were vertically suspended in the steam from a chest filled with milk, so that there was constantly a layer of milk above the extremities of the leaden tubes. After ♦ [I am anxious to acknowledge the liberality with which Messrs. Fortnum and Mason put a large and valuable collection of specimens at my disposal, for experiment as well as for exhibition. — J. B.] t Among the specimens of Mr. Gamble's process were cairs head with turtle-gravy, soup of ox-cheek, ox-tail, giblet, and mulligatawny, and mutton broth, stewed rump-steaks, mackerel, stewed eels, lobsters, tripe, cream, and butter. Some of these were opened and cooked during Mr. Barlow's discourse. A scientific interest has attached itself to these aiticles of luxury, as well as to those of M. Appert, because their preservation depends on the delicate ad- justment of the heat employed in preparing them, between the temperature which would destroy their flavour, and that which would be insufficient to ensure their remaining uninjured in tropical climates. 78 Rev, J. Barlow on the application [March 30, having received sufficient heat, the bottles and their contents were suffered to cool, and, when cold, the leaden tubes were carefully closed under the surface of the milk, to prevent the admission of air. A bottle of milk thus prepared, which had been kept fourteen months, was opened, and found unaltered except by the separation of a small quantity of cream.* 2. Process of M. Francis Bernard Bekaert. This method differs from that of M. Mabru in the addition of a few drops of solution of carbonate of soda to the milk before it is subjected to the boiling temperature. In this process the milk may be kept in glass bottles, which, however, must be carefully corked. After the weak alkaline solution has been added the whole is heated in water, gradually raised to the temperature of 212°, and after- wards is slowly cooled. A bottle of milk thus prepared was per- fectly sweet and fresh after having been kept ten weeks. f 3. Process of Mr. E. D. Moore. Mr. Moore removes from the milk its constituent water, retaining its component elements. The condition in which the butter, caseine, &c., are preserved is such, that when the paste comes to be again united with water, the milk reassumes its original appearance and flavour. 4. Solidified Milk. By successive applications of carefully regulated heat, and by the addition of a substance which he has discovered, M. Fadeuilhe has succeeded in removing from the milk those of its constituents which, as he believes, cause it to decompose, and are also injurious to health. Sugar and a small quantity of gum tragacanth are then added to the residue, which is ultimately solidified by the prolonged action of a constantly varied temperature. Unlike the preparations of milk already described, the solidified milk of M. Fadeuilhe does not require to be kept out of contact of air. It is sent into the market in paper wrappers. F. Meat-Biscuits. These may be regarded as the full developement and scien- tific perfection of the pemican principle. Pemican is dried meat, thoroughly mixed with fat, sugar, or spice. Meat-biscuit consists of flour, baked with a solution of the nutritious ingredients of flesh, * A full description of the details of M. Mabru's process will be found in Cosmos, Vol. V. p. 325. It was to the good offices of the Abbe Moigno, the learned editor of that journal, that Mr. Barlow was indebted for this specimen of milk, as well as for the preserved provisions of M. Appert. t The small quantity of air necessarily intervening between the cork and the surface of the milk in the bottle did not appear to have produced any effect. 1855.] of Chemistry to the Preservation of Food. 79 separated from its fibre. It will keep, when dry, for an unlimited period. The Council-Medal, at the Great Exhibition of 1851, was awarded to the meat-biscuit of Gail Borden. " Ten pounds of this substance, with a proper allowance of water, afford, both in bulk and nutriment, food sufficient to support the physical and mental powers of a healthy working man for a month."* A specimen of this meat-biscuit was exhibited, as was also a meat-cake prepared by M. Pouteau, of Bucharest, from flour and the soluble constituents of beef. Each cake affords three good meals, weighs 7i ounces, divided into three rations of 2^ ounces each.f The combinations of Chocolate with milk paste or solidified milk, respectively prepared by Messrs. Moore and Fadeuilhe, may be regarded as an important supplement to this class of preserved provisions. To these Dr. Bence Jones has made a valuable addi- tion by his Extract of Tea. This extract, a specimen of which, prepared in the laboratory of the Institution, was exhibited, is made by evaporating a strong infusion of tea to dryness in a water-bath. If intended for ready use in travelling, it should be well mixed with twenty times its weight of sugar : a tea-spoonful of this pre- paration is sufficient to make a cup of tea. J [J. B.] * Reports of the Juries, p. 65. t O'Brien's Danubian Provinces, 2nd Edition. X In his " Report to the Hudson's Bay Company," Dr. Rae refers to one of the islands, discovered in the expedition which he relates, having been named Bence Jones, *' after the distinguished medical man and analytical chemist of that name, to whose kindness I and my party were much indebted for having proposed the use and prepared some extract of tea for the expedition." — Household Words^ February 1855, p. 18. Mr. Faraday brought before the Members a specimen of rolled and laminated Aluminium from Dr. Percy. It had been prepared by Mr. A. Dick, and was obtained by the direct action of sodium on cryolite, — which being a fluoride of aluminium and sodium is by more sodium resolved into aluminium and fluoride of sodium. Vol. II. 80 General Monthly Meeting, [April 2, GENERAL MONTHLY MEETING, Monday, April 2. Aaron Asher Goldsmid, Esq. in the Chair. Eustace Anderson, Esq. Andrew Whyte Barclay, M,D. and Thomas Parry Woodcock, Esq. were duly elected Members of the Royal Institution. John Baily, Esq. Q.C. John Dickinson, Esq Charles Beevor, Esq. Henry Bradbury, Esq were admitted Members of the Royal Institution. Rev. George Delgarno Hill. Henry M. Noad, Esq. Ph.D. F.R.S. A Special Vote of Thanks was returned to His Grace the Duke of Northumberland, the President, for his Present of a magnificently bound copy of Rosellini's " Monumenti dell' Egitto e della Nubia," in nine volumes 8vo, with an Atlas of Plates in three volumes folio. The following Presents were announced, and the thanks of the Members returned for the same. From Her Majesty's Government {through Sir H. De la 5ecAe)— Catalogue of Speci- mens (at the Museum of Practical Geology) illustrative of the Composi- tion and Manufacture of British Pottery and Porcelain, By Sir H. De la Beche and T. Reeks. 8vo. 1855. Actuaries, Institute of—The Assurance Magazine. No. XIX. Svo. 1855. Anderson, W. J. Esq. M.R.I, {the ^wf/ior)— Continued Fever in Children. 12mo. 1854. Astronomical Society, Royal— Monthly Notices. Vol. XIV. and Vol. XV. No. 4. Svo. 1855. Memoirs. Vol. XXIII. 4to. 1854. Bai/erische Ahademie der Wissenschaften, die Konigliche — Abhandlungen, Band VII. 2te Abtheilung. 4to. Munich, 1854. Bulletin fur 1853. 4to. Magnetische Ortsbestimmungen in Bayem. Von Dr. J. Lament. Theil I. 8vo. 1854. Annalen der Koniglichen Sternwarte bei Miincheu. Band VI. Von Dr. J. Lamont. Svo, 1854, 1855.] General Monthly Meeting. 81 Bradbury^ Henrti^ Esq. M.RI. — The Feras of Great Britain and Ireland. By T. Moore, F.L.S. Edited by J. Lindley, Ph.D. F.L.S. Part I. fol. 1855. Bell, Jacob, Esq. AT. /^./.—Pharmaceutical Journal, for March, 1855. 8vo. Boosey, Messrs. (the Publishers) — The Musical World for March, 1855. 4to. British Architects, Foi/al Institute of — Proceedings in March, 1855. 4to. Civil Entjifieers, Institution o/"— Proceedings in March, 1855. 8vo. East India Compani/, the Hon. — Catalogue of the Arabic, Persian, and Hin- dustany MSS. of the Libraries of the King of Oude. Compiled by A. Sprenger, M.D. Vol. I. 8vo. Calcutta, 1854. Glossary of Judicial and Revenue Terms, and of Useful Words occurring in Official Documents relating to the administration of the Government of British India. By H. H. Wilson, M.A. F.R.S. 4to. 1855. Editors— The Medical Circular for March, 1855. 8vo. The Athenaeum for March, 1855. 4to- The Practical Mechanic's Journal for April, 1855. 4to. The Mechanics* Magazine for April, 1855. 8vo. The Journal of Gas-Lighting for April, 1855. 4to. Deutsches Athenaum fiir Milrz, 1855. 4to. Everest, Rev. li. M.A. (the Author) — Journey through the United States and part of Canada. 8vo. 1855. On Social Degradation. 8vo. 1855. Faraday, Professor, D.C.L. F.E.S. — Monatsbericht der Kbnigl. Preuss. Akaidemie, January und February, 1855. 8vo. Berlin. Graham, George, Esq. Registrar- General — Report of the Registrar-General for March, 1855. 8vo. Greenwich Royal Observatory — Astronomical, Magnetical, and Meteorological Observations in 1853. 4to. 1855. Irish Academij, the Royal — Memoirs, Vol. XXV. Part 5. 4to. 1855. Proceedings, Vol. VI. Part 1. 8vo. 1854. Northumberland, Duke of, K.G. F.R.S. President R.I. — I Monumenti dell' Egittoe della Nubia dal Ippolito Rosellini. 9 vols. 8vo., and 3 vols. fol. Pisa, 1832-44. Novello, Mr. (the Publisher) — The Musical Times for March, 1855. 4to. Photographic Society — Journal, No 28. 8vo. 1855. Royal Society of London — Proceedings, Vol. VII. Nos. 9, 10. 8vo. 1855. Radcliffe Trustees, Oxford — Astronomical Observations made at the Radcliffe Observatory, Oxford, in 1852. 8vo. 1854. Snow, John, M.D. (the Author) -On the Mode of communication of Cholera. 8vo. 1855. Society of Arts — Journal for March, 1855. 8vo. Sykes, Col. F.R.S. (the ^uf^or^— Statistics of Nice Maritime. 8vo. 1855. On the Miniature Chaityas found in the Ruins of the Temple of Samath, near Benares. 8vo. Address at his Installation as Lord Rector of the University, Aberdeen. 8vo. 1854. Taylor, Rev. W. F.R.S. itf. /?./.— Magazine for the Blind, March, 1855. 4to. Webster, John, M.D. F.R.S. 3/./?./.— General Reports of the Royal Hospitals of Bridewell and Bethlem, &c. for 1854. 8vo. 1855. g2 82 Mr. Huxley on the Progressive [April 20, WEEKLY EVENING MEETING, Friday, April 20. William Robert Grove, Esq. M.A. Q.C. F.R.S. Vice-President, in the Chair. T. H. Huxley, Esq. F.R,S. On certain Zoological Arguments commonly adduced in favour of the hypothesis of tJie Progressive Development of Animal Life in Time, When tlie fact that fossilized animal forms are no lusus natur<2, but are truly the remains of ancient living worlds, was once fully admitted, it became a highly interesting problem to determine what relation these ancient forms of life bore to those now in ex- istence. The general result of inquiries made in this direction is, that the further we go back in time, the more different are the forms of life from those which now inhabit the globe, though this rule is by no means without exceptions. Admitting the difference, however, the next question is, what is its amount? Now it appears, that while the Palaeozoic species are probably always distinct from the modern, and the genera are very commonly so, the orders are but rarely different, and the great classes and sub-kingdoms never. In all past time we find no animal about whose proper sub-kingdom, whether that of the Protozoa, Radiata, Annulosa, Mollusca, and Vertebraia, there can be the slightest doubt ; and these great divi- sions are those which we have represented at the present day. In the same way, if we consider the Classes, e. g. Mammalia, Aves, hisecta, Cephalopoda, Actinozoa, &c., we find absolutely no remains which lead us to establish a class type distinct from those now existing, and it is only when we descend to groups having the rank of Orders that we meet with types which no longer possess any living representatives. It is curious to remark again, that, notwith- standing the enormous lapse of time of which we possess authentic records, the extinct ordinal types are exceedingly few, and more than half of them belong to the same class — JReptilia. The extinct ordinal Reptilian types are those of the Pachypoda, Pterodactyla, Enaliosauria, and Labyrinthodonta ; nor are we at present acquainted with any other extinct order of Vertebrata. Among the Annulosa (including in this division the Echinoder- 1855.] Development of Animal Life if t Time. 83 mata,) we find two extinct ordinal types only, tlie J'rilobita and the Cystidece. Among the Mollusca there is absolutely no extinct ordinal type ; nor among the Radiata (Actinozoa and Hydrozoa) ; nor is there any among the Protozoa. The naturalist who takes a wide view of fossil forms, in connec- tion with existing life, can hardly recognise in these results anything but strong evidence in favour of the belief that a general uniformity has prevailed among the operations of Nature, through all time of which we have any record. Nevertheless, whatever the amount of the difference, and however one may be inclined to estimate its value, there is no doubt that the living beings of the past differed from those of the present period ; and ugain, that those of each great epoch, have differed from those which preceded, and from those which followed them. That there has been a succession of living forms in time, in fact, is admitted by all ; but to the inquiry — What is the law of that succession ? differ- ent answers are given ; one school affirming that the law is known, the other that it is for the present undiscovered. According to the affirmative doctrine, commonly called the theory of Progressive Development, the history of life, as a whole, in the past, is analogous to the history of each individual life in the present ; and as the law of progress of every living creature now, is from a less perfect to a more perfect, from a less complex to a more complex state — so the law of progress of living nature in the past, was of the same nature ; and the earlier forms of life were less complex, more embryonic, than the later. In the general mind this theory finds ready acceptance, from its falling in with the popular notion, that one of the lower animals, e.g. a fish, is a higher one, e. g. a mammal, arrested in development ; that it is, as it were, less trouble to make a fish than a mammal. But the speaker pointed out the extreme fallacy of this notion ; the real law of development being, that the progress of a higher animal in develop- ment is not through the forms of the lower, but through forms which are common to both lower and higher : a fish, for instance, deviating as widely from the common Vertebrate plan as a mammal. The Progression theory, however, after all, resolves itself very nearly into a question of the structure of fish-tails. If, in fact, we enumerate the oldest known undoubted animal remains, we find them to be Graptolites, Lingulce, Phyllopoda, Trilobites, and Cartilaginotis fishes. The Graptolites, whether we regard 'them os Hydrozoa, Anthozoa,' or Polyzoa, (and the recent discoveries of Mr. Logan would strongly favour the opinion that they belong to the last division,) are cer- tainly in no respect embryonic forms. Nor have any traces of Spongiadce or Foraminifera (creatures unquestionably far below them in organization,) been yet found in the same or contem|)o- 84 Mr, Huxley on the Progressive [April 20, raneous beds. Lingulce^ again, are very aberrant BracMopoda, in nowise comparable to the embryonic forms of any mollusk ; Phyllopods are the highest Entomostraca ; and the Hymenocaris vermicauda discovered by Mr. Salter in the Lingula beds, is closely allied to Nebalia, the highest Phyllopod and that which approaches most nearly to the Podopthalmia. And just as Hymenocaris stands between the other Entomostraca and the Podopthalmia, so the Trilobita stand between the Eidjmostraca and the Edriopthalmia. Nor can anything be less founded than the comparison of the Trilo- bita with embryonic forms of Crustacea ; the early development of the ventral surface and its appendages being characteristic of the latter ; while it is precisely these parts which have not yet been discovered in the Trilobita, the dorsal surface, last formed in order of development, being extremely well developed. The hivertebrata of the earliest period, then, afford no ground for the Progressionist doctrine. Do the Vertebrata ? These are cartilaginous fish. Now Mr. Huxley pointed out that it is admitted on all sides that the brain, organs of sense, and re- productive apparatus, are much more highly developed in these fishes than any others ; and he quoted the authority of Prof. Owen,* to the effect that no great weight^is to be placed upon the cartilagi- nous nature of the skeleton as an embryonic character. There remained, therefore, only the heterocercality of the tail, upon which so much stress has been laid by Prof. Agassiz. The argument made use of by this philosopher may be thus shortly stated : — Homocercal fishes have in their embryonic state heterocercal tails ; therefore, heterocercality is, so far, a mark of an embryonic state as compared with homocercality ; and the earlier, heterocercal fish are embryonic as compared with the later, homocercal. The whole of this argum.ent was based upon M. Yogt's examina- tion of the development of the Coregonus, one of the Salmonidce ; the tail of Coregonus being found to pass through a so-called hetero- cercal state in its passage to its perfect form.f For the argument to have any validity, however, two conditions are necessary. 1. That the tails of the Salmonidce should be homocercal, in the same sense as those of other homocercal fish. 2. That they should be really heterocercal, and not homocercal, in their earliest con- dition. On examination, however, it turns out that neither of these conditions holds good. In the first place, the tails of the Salmonidce, and very probably of all the Physostomi are not homocercal at all, but to all intents and purposes intensely heterocercal : the chorda dorsalis in the Salmon, for instance, stretching far into the upper lobe of the tail. The wide difference of this structure from true homocercality is at once obvious, if the tails of the Salmonidce be ♦ Lectures on the Comparative Anatomy of the Vertebrata, pp. 146-7. t Von BUr had already pointed out this circumstance in Cyprinus, and the rqhition of the foetal tail to the permanent condition in cartilaginous fishes. — See his ** Entwickelungsgeschichte der Fische," p. 36. 1855.] Development of Animal Life in Time. 85 compared with those of Scomber scomhrus, Gadus ceglefinus, &c. In the latter, the tail is truly homocercal, the rays of the caudal fin being arranged symmetrically above and below the axis of the spinal column. All M. Vogt's evidence, therefore, goes to show merely that a heterocercal fish is heterocercal at a given period of embryonic life ; and in no way affects the truly homocercal fishes. In the second place, it appears to have been forgotten that, as M. Vogt's own excellent observations abundantly demonstrate, this heterocercal state of the tail is a comparatively late one in Coregonus, and that, at first, the tail is perfectly symmetrical, i.e. homocercal. In fact, all the evidence on fish development which we possess, is to the effect that Homocercality is the younger, Heterocercal ity the more advanced condition : a result which is diametrically opposed to that which has so long passed current, but which is in perfect accordance with the ordinary laws of development ; the asymmetri- cal being, as a rule, subsequent in the order of development to the symmetrical. The speaker then concluded by observing that a careful consider- ation of the facts of Palaeontology seemed to lead to these results : 1. That there is no real parallel between the successive forms assumed in the development of the life of the individual at present, and those which have appeared at different epochs in the past ; and 2. That the particular argument supposed to be deduced from the heterocercal ity of the ancient fishes is based on an error, the evidence from this source, if worth anything, tending in the oppo- site direction. At the same time, while freely criticising what he considered to be a fallacious doctrine, Mr. Huxley expressly disclaimed the slightest intention of desiring to depreciate the brilliant services which its original propounder had rendered to science. [T. H. H.] A series of specimens of Aluminium, prepared by M. St. Claire Deville, in Paris, were laid upon the Library table by Dr. Hofmann. These specimens consisted of a medal, with the head of the Em- peror Napoleon III., two bars, a watch wheel, and a piece of copper plated with Aluminium. A large piece of Tellurium, pre- pared by Dr. Lowe, of Vienna, was likewise exhibited by Dr. Hofmann. 86 Sir Charles Lyell [April 27, WEEKLY EVENING MEETING, Friday, April 27. The Duke of Northumberland, K.G. F.R.S. President, in the Chair. Sir Charles Lyell, F.R.S. On certain Trains of Erratic Blocks on the Western borders of Massachusetts^ United States. On the western borders of the State of Massachusetts, in Berkshire, and on the eastern confines of the adjoining State of New York, a great number of erratic blocks are seen, remarkable for their large size and their distribution in long parallel trains, each of them continuous in nearly straight lines over hill and dale, for the dis- tance of five, ten, or twenty miles or more. These trains are of geological interest, not only from their length, and the size of the blocks, but also from the precision with which they can be traced to their starting points, and the low latitudes in which these starting points are situated. The area alluded to occurs in lat. 42° 25' south, corresponding to that of the north of Portugal ; and the western borders of Berkshire, where they join the State of New York, are about 130 miles from the Atlantic coast, in a direction due west of the city of Boston, in Massachusetts. In the accompanying plan. Fig. 1, it will be observed that the mountain ranges ABC run N.N.E. and S.S.W., whereas the trains of erratic blocks (from No. 1 to No. 7 inclusive,) have a direction nearly transverse to these ranges, and consequently to the intervening valleys, their direction being about N.W. and S.E. In one sense we may affirm that the course of the stones has no relation whatever to the present configuration of the country, be- cause the present drainage or flow of the rivers is quite in a different direction ; but in another point of view we shall find that a close relation can be made out between the actual inequalities of hill and dale, and the course and mode of dispersion of the erratics ; so that there is good reason to infer that the superficial inequalities were very nearly what they are now, before any of the trains originated. 1855.] on Trains of Erratic Blocks in Massachusetts. 87 Distance in a straight line between the mountain ranges A and C, about eight miles. Map, showing the relative position and direction of seven trains of erratic blocks in Berkshire, Massachusetts, and in part of the State of New York.* A. Canaan range, in the State of New York. The crest consists of green chloritic rock. B. Richmond range (part of the Taconic range of Hitchcock ?) the western division of which consists in Merriman's Mount of the same green rock as A , but in a more schistose form, while the eastern division is composed of slaty limestone. C. The Lenox range, consisting in part of mica-schist, and in some dis- tricts of crystalline limestone. ♦ As the description of the trains could not be undei-stood without a ground plan, the above copy of a diagram, exhibited during the discourse, is thought necessary ; but it makes no pretensions to geographical accuracy, the speaker and his companion Prof. Hall having been unable to procure a good map of the district, ^u which to lay down in detail the results of their observations. 88 Sir Charles Lyell [April 27, d. Knob in the range A, from -which most of the train No. 6, is supposed to have been derived. c. Supposed starting point of the train No. 5, in the range A. f. Hiatus of 175 yards, or space without blocks. g. Sliorman's House. h. Perry's Peak. k. Flat Rock. /. Merriman's Mount. in. Dupey's Mount. n Largest block of train, No. 6. p. Point of divergence of part of the train No. 6, where a branch is sent off to No. 5. No. 1. The most southerly train examined by Messrs. Hall and Lyell, between Stockbridge and Richmond, composed of blocks of black slate, blue limestone, and some of the green Canaan rock, with here and there a boulder of white quartz. No. 2. Train composed chiefly of large limestone masses, some of them divided into two or more fragments, by natural joints. No. 3. Train composed of blocks of limestone and the green Canaan rock ; passes south of the Richmond Station on the Albany and Boston railway ; is less defined than Nos. 1 and 2. No 4. Train chiefly of limestone blocks, some of them 30 feet in diameter, running to the north-west of the Richmond Station, and passing south of the Methodist Meeting-house, where it is intersected by a railway cutting. No. 5. South train of Dr. Reid, composed entirely of large blocks of the green chloritic Canaan rock ; passes north of the Old Richmond Meeting-house, and is three-quarters of a mile north of the preceding train fNo. 4). No. 6. The great or principal train (north train of Dr. Reid), composed of very large blocks of the Canaan rock, diverges at p, and unites by a branch with train No. 5. No. 7. A well-defined train of limestone blocks, with a few of the Canaan rock, traced from the Richmond to the slope of the Lenox range. Dr. Reid, the agriculturist of Berkshire, first called attention in 1842 and 1845 to these phenomena. Professor Hitchcock con- tributed many valuable observations in 1844, and Professors Henry D. and William B. Rogers treated of the same subject in 1846.* The district was re-examined in October 1852, by Professor J. Hall and Sir Charles Lyell, by whom some of the data referred to in this discourse were ascertained. Within the area particularly referred to, the trains Nos. 5 and 6 are the most conspicuous, by their length and by the magnitude and frequency of the blocks composing them. These fragments consist of a green chloritic rock, remarkably tough, sometimes compact, but occasionally schistose. It is met with in place at c/, in the highest crest of the Canaan ridge, and reappears in its more slaty form in the western division of the Richmond ridge B. at Z, or Merriman's Mount. It passes on the one hand into a quartzose conglomerate, * " Boston Journal of Natural History," for .Tune 1846. 1855.] on Trains of Erratic Blocks in Massachusetts. 89 and on the other, when most metamorphic, into a crystalline rock, in which sometimes chlorite, sometimes hornblende and felspar are developed. A large proportion of the green fragments, in trains 5 and 6, have evidently come from the ridge A, and a large propor- tion of the whole from its highest summit d, upon which fragments often 30 feet in length may now be seen, some of them having probably constituted for years the exposed crest of the ridge, and having in that position acquired a smoothed and rounded outline so characteristic of the protuberances of hard rock in regions where erratics and glacial striae abound. Such dome-shaped masses are called " roches moutonnees," on the borders of Swiss glaciers. Several of the fragments having this shape, and lying on the crest of A, have been slightly removed from their original position, as if just ready to set out on their travels. They are angular in their lower parts, where they exhibit such an outline as the jointed rock would possess if a great fragment fell from an undermined cliff. To the westward of the ridge A no similar green blocks are to be found, not even a small number, such as we might have expected to roll down to the base of a hill having so steep a western decli- vity. It is evident, therefore, that the propelling power, whatever it was, acted exclusively in a south-easterly direction. Dr. Reid has traced the train No. 5 for more than ten, and No. 6 for more than twenty miles to the south-east, crossing the Richmond and Lenox mountains B and C, and probably extending beyond the points to which they have already been followed. Messrs. Hall and Lyell found both trains extremely well-defined after they emerge from the Richmond range, but by no means so distinct in their passage over the first valley between A and B. A great number of blocks have collected at the base of d, Fig. 1, or the highest knob before alluded to of A, particularly around ^, or Sherman's House. From this point to the Richmond range, a nearly continuous stream may be traced, and the blocks are seen to pass through a gap or depression, in the eastern division of the ridge B, between Flat Rock and Merriman's Mount, k and /. But when we attempt to follow the other train. No. 5, from its supposed point of origin e, (a spot about half a mile distant from d before alluded to,) we find at /an hiatus, not less than 175 yards long, where there are no erratics. This break is not caused by the stones having been used up for building, no such materials being obser- vable in the walls enclosing fields, or in the farm-houses in the neighbourhood. A vast number of blocks seem to have crossed the valley in a direct line between A and B, and to have accumulated on the north-western slope of Merriman's Mount /, as well as to the south of it, around Dupey's Mount m ; and they seem to have crossed the Richmond ridge by depressions both to the north and south of Dupey's Mount, those to the north proceeding westward to join the train No. 6. The number of large blocks lying on the west slope of Dupey's Mount, and many of them to the south of 90 Sir Charles Lyell [April 27, the line which would connect the southern train, No. 5, with its supposed starting point e, is very great. One of these, 24 feet long, is poised upon another which is about 19 feet in length. The largest of all, composed like the rest of the green Canaan rock, lies on the west flank of Dupey's Mount, and is called " the Alderman." Dr. Keid measured it, and ascertained that it is above 90 feet in diameter, and not much under 300 feet in circumference. At some points about 40 or 50 blocks, the smallest of them larger than a camel, may be seen at once. Among the larger masses the best known, in consequence of its proximity to the Richmond Meeting- house, belongs to train No. 6, and is that marked n on the plan, Fig. 1. According to the measurement of Messrs. Hall and Lyell it is 52 feet long, by 40 in width, its height above the drift in which it is partially buried being 15 feet. At the distance of several yards occurs a smaller block, three or four feet in height, 20 feet long, and 14 broad, composed of the same compact chloritic rock, and evidently a detached fragment from the bigger mass, to the lower and angular part of which it would fit on exactly. This erratic {n) has a regu- larly rounded top, worn and smoothed like the roches moutonnees before mentioned, but no part of the attrition can have occurred since it left its parent rock, the angles of the lower portion being quite sharp and unblunted. After the two great trains, Nos. 5 and 6, have crossed the ridge B, and entered the Richmond valley, which is about four miles broad, and about 800 feet deep below the crests of A and B, each train is exceedingly well defined. They are about half a mile apart, the train No. 6 varying in width from 100 to 300 feet, the space intervening between them usually very free from erratics, but here and there a solitary large straggler being visible. At one point p, Fig. 1 , part of the train No. 6 diverges and forms a branch uniting with No. 5. The average size of the blocks of all the seven trains laid down on the plan lessens sensibly in proportion as we recede from their point of departure, yet not with any regularity, a huge block recur- ring here and there in the midst of a train of smaller ones. Many which have wandered farthest from their parent rock retain their angles extremely fresh and sharp. Almost everywhere beneath the trains is a deposit of sand, nmd, gravel, and stones, for the most part unstratified, and resembling the " northern drift " of Great Britain and parts of the north of Europe. It varies in thickness from 10 to 50 feet, being of greatest depth in the valleys. The uppermost portion is occasionally, though rarely, stratified ; and where stratification occurs, it seems as if the mass first thrown down had been acted upon by currents, and partially rearranged. This drift has been well exposed in some recent railway cuttings, where it is occasionally seen to be 20 or 30 feet thick, immediately under several of the trains before alluded to. The stones in general are more rounded than the erraticsal ready described ; occasionally some 1855.] on Trains of Erratic Blocks in Massachusetts. 91 are seen with one or more flattened, smooth, striated, or furrowed sides. They consist invariably, like the seven trains before men- tioned, of kinds of rock only met with in the region lying to the north-west. In one cutting, the drift below the main train No. 6 is 30 feet thick, and contains one or two angular blocks of the green Canaan rock, of considerable, but not of the largest size. There are no appearances here or elsewhere warranting the conclu- sion that the trains owed their origin to the removal of an upper portion of the covering of drift, the lighter materials having been washed away, and the heavier made to stand out in relief. On the contrary, the erratics of each train, whether large or small, look as if they had dropped down over the linear spaces where they are now strewed, on the surface of hill and valley, equally where the drift is thickest, as where it is very thin or wanting. As a rule, the drift contains no blocks of the first magnitude, although a few occur, and some of the biggest are partially buried in drift, showing that the transport of the heavier, and of a certain portion of the lighter materials, was contemporaneous. Almost in every place where the removal of the superficial detritus has exposed the underlying rock, a polished, striated, and furrowed surface is seen, like that underneath the modern glaciers of the Alps. The direction of the rectilinear furrows or grooves has been proved by a multitude of observations, made by Professor Hitchcock in this and other adjoining parts of Massachusetts and New York, to be from N.W. to S.E, or similar to the course of the large erratics.* The same geologist has pointed out that such ridges as A B and C are smooth and furrowed, not only on their tops, but sometimes 100 or 200 feet below, on their north-western sides ; whereas, on their south-eastern declivities, if steep, there has been no such action, although these also are grooved and polished where their slope is gentle. The furrows, which are from an inch to a foot in depth, usually cross the strike of the highly inclined slates and slaty limestones at a considerable angle,, and in such a manner as to demonstrate that the strata of the ridges A B and C, and of the intervening valleys, bent as they are into a series of anticlinal and synclinal folds, were already in their present position, and had even suffered aqueous denudation before the drift was thrown down upon them, and therefore long before the distri- bution of the erratics above described had taken place. Although the trains, Nos. 5 and 6, are the most conspicuous, several of the others are well defined, and contain limestone blocks 30 feet in diameter. Thus No. 7 was seen on the western flank of the Leno\ range, and followed across the Richmond valley to the eastern side of the ridge B, where the limestone, which has supplied the travelled masses, is in situ. In like manner, Messrs. Hall and Lyell observed, half a mile south of Pittsfield, enormous ♦ ** Final Report on Geology of Massachusetts," p. 383, et seq. 1841. 92 Sir Charles Lyell [April 27, blocks of mica-schist, from 30 to 50 feet in their longest diameter, on the south-east side of the Lenox range C ; whereas no similar fragments of mica-schist, whether large or small, are found in any part of the Richmond valley, or on the ridge B, or indeed anywhere between A and the Hudson river. Some boulders of white quartz rock, two or three feet in diameter, make a part of almost every train, as well as of the subjacent drift, and these may be traced to hills, between the Canaan ridge and the Hudson river, where the Potsdam sandstone has been altered into quartzite. Sir Charles then proceeded to explain his theory. He believes that all the large erratics have been transported to the places they now occupy by floating ice, — not by icebergs, nor by terrestrial glaciers, but by coast-ice. The hypothesis of glaciers is out of the question ; because, even if we could imagine that in lat. 42° 30' N., the ridges ABC, now only from 1000 to 2000 feet above the sea, once rose, and that at a period, geologically speaking, very modern, to such an elevation as to enable them to generate glaciers, still such glaciers could not have descended from the higher regions in one direction only. They would have radiated from a centre, carrying as many blocks westward as eastward. Their course, moreover, would have been principally S.S.W., or down the valleys now separating the ridges, instead of being south-east, or almost at right angles to the valleys. If, on the other hand, we assume that the country was lower instead of higher, so as to have been sub- merged beneath the waters of a sea, in which icebergs floated annually from arctic regions, these bergs might bring with them gravel and stones of northern origin, but could not without the aid of coast-ice become freighted with blocks derived from the very region referred to in this discourse, (lat. 42" N.) The northern ice might aid, by chilling the waters of the ocean, and increasing the quantity of coast-ice in a low latitude, but it could do little more. N.W. Canaan. A Sea d, e Masses of floating ice carrying fragments of rock. Suppose the highest peaks of the ridges ABC, in the annexed dia- gram, to be alone above water, forming islands, and d e to he masses of floating ice which drifted across the Canaan and Richmond valleys, at a time when they were marine channels, separating islands, or rather chains of islands, having a N.N.E. and S.S.W. direction. A fragment of ice, such as d, freighted with a block from A, might run aground, and add to the heap of erratics at the N.W. base of the island B, or passing through a sound between B and the next 1855.] on Trains of Erratic Blocks at Massachusetts. 93 island of the same group, might float on till it reached the clianuel between B and C. Year after year two such exposed cliffs in tlie Canaan range as c?and e (Fig. 1), undermined ])y the waves, might serve as the points of departure of blocks, composing the trains Nos. 5 and 6. It may be objected that oceanic currents could not always have had the same direction ; this may be true, but during a short season of the year when the ice was breaking up the pre- vailing current may have always run S.E. If it be asked why the blocks of each train are not more scattered, especially when far from their source, it may be observed, that after passing through sounds separating islands, they issued again from a new and narrow starting point ; moreover, we must not exaggerate the regularity of the trains, as their width is sometimes twice as great in one place as in another ; and No. 6 sends off a branch at p, which joins No. 5. There are also stragglers, or large blocks, here and there in the spaces between the two trains. As to the dis- tance to which any given block would be carried, that must have depended on a variety of circumstances ; such as the strength of the current, the direction of the wind, the weight of the block, or the quantity and draught of the ice attached to it. The smaller frag- ments would, on the whole, have the best chance of going farthest ; because, in the first place, they were more numerous, and then being lighter, they required less ice to float them, and would not ground so readily on shoals, or if stranded, would be more easily started again on their travels. Many of the blocks, which at first sight seem to consist of single masses, are found, when examined, to be made up of two, three, or more pieces, divided by natural joints. In case of a second removal by ice, one or* more portions would become detached and be drifted to different points further on. Whenever this happened the original size would be lessened, and the angularity of the block previously worn by the breakers would be restored, and this tendency to split may explain why some of the far-transported fragments remain so angular. In the ravine between Merriman's Mount and Flat Rock {k and /, Fig. 1), the erratics, instead of following a N.W. and S.E. course, run within 10 or 15 degrees west and east; and Messrs. Hall and Lyell observed that the glacial furrows there on the exposed rocks below deviated in like manner from the normal direction, and were directed like the train of erratics nearly west and east. They were told that the like deflection, both of trains and furrows, was observ- able where Nos. 5 and 6 cross the Lenox range ; and this deflection is so represented on the plan (Fig. 1); although the speaker had not an opportunity of verifying the fact. The direction of floating ice, when threading the sounds separating islands, would be governed by the shape of the land and the marine channels, and might be expected to differ from the direction of currents flowing in the open sea between chains of islands. Sir C. Lyell endeavoured in 1842, when explaining the origin of 94 Sir Charles Lyell [April 27, drift, boulders, and glacial furrows in the neighbourhood of the Falls of Niagara, both in Canada and in the State of New York,* to show that the whole region, with its elevated platforms and its valleys, had first gone down gradually, and had then been re- elevated during the glacial period. All geologists who are acquainted with Berkshire, Massachusetts, are agreed that the position of the erratics cannot be explained by the subsequent unequal elevation of the mountain ranges, as if B, for example, had been uplifted to a greater height than A, after the great boulders had been stranded on B. It is clear that the ridge B has inter- cepted many erratics on its north-western side, as it would do now, if submerged, and the blocks have chiefly crossed through gaps or depressions in B. The glacial furrows also are such as would be made on the fixed rocks, after they had already assumed their actual position, and when the present hills and valleys existed. Although the principal mass of drift had accumulated before the trains, yet we see some of the biggest blocks partially buried in drift. This we might have expected, according to the hypothesis above suggested, for coast-ice, such as forms annually in the Gulf of St. Lawrence and along the coast of Labrador, does not merely bear away great stones but also mud, sand, and gravel. The speaker exhibited a drawing of a large angular block of sandstone, about eight feet in diameter, which he and Mr. J. W. Dawson saw in 1852, stranded on the mud-flats near the mouth of the Petitcodiac estuary, where it joins the Bay of Fundy, and where the water is salt. The ferrymen stated that this block was brought down by ice three years before, from a cliff" several miles up the river. About the year 1850 much larger blocks of sandstone were removed by coast-ice from the base of a perpendicular cYi^ at the South Joggins, in the Bay of Fundy, in salt water, and floated for about half a mile, where they dropped or were grounded on one side of the pier built for loading vessels with coal. The vessels being thereby prevented from nearing the pier it was found necessary to blast these ice-borne rocks, at low tide, with gunpowder. All this occurred in latitude 46^ N., corresponding to that of Bordeaux ; and when we bear in mind that the Bay of Fundy opens towards the south, and is therefore never invaded by icebergs, such as are stranded occasionally near St. John's, Newfoundland, or such as are annually drifted far to the south of the Bay of Fundy in the open ocean, we may well imagine that, with a different configuration of the land, coast-ice may once have exerted great power as far south as the latitude of Berkshire. The buoyant power of sheets of ice, even of moderate thickness, is so great that the magnitude of erratics depends more on the dimensions of the fragments into which rocks undermined by the sea happen to split, than on the peculiar intensity of the frost in that region. * "Travels in North America," Vol. I., p. 99 ; and Vol. II., p. 48. 1855.] on Trains of Erratic Blocks in Massachusetts. 95 It has been objected to the theory of submergence that the great train, No. 6, has climbed a part of the ridge B, higher than its supposed starting point in A. But there are no exact barometrical or trigonometrical data for this assertion. Messrs. Hall and Lyell could only estimate roughly the relative heights of the knob d in A, and that of the pass between k and / in B, by means of a spirit- level, as they stood on the Canaan knob. It appeared to them that the gap in B, or the ravine between Merriman's Mount and Flat Kock, is 50 or 100 feet below the highest crest of A, in which case the objection falls to the ground. Some of the erratics of No. 6, in the Richmond valley, have probably come from an elevated point in Merriman's Mount, and therefore present no difficulty, since that mount consists of the green chloritic rock, but others have come from the Canaan ridge, and have crossed the ridge B, as before stated. If it could be shown that some of these stones repose on B, at points actually higher than the crest of A, the fact would be important, but by no means inexplicable by the glacial theory. Mr. C. Darwin has shown, that during the gradual subsi- dence and submergence of a coast situated in high latitudes, packed ice with stones frozen into it is continually driven up on ^tlie sea- beach above high-water mark, and if the land be going down at the rate of a few inches in a year, the boulders, by being simply kept up to the sea level, will slowly climb up the hills higher and higher, so that a ridge after sinking may, when it re-emerges, have stones lodged upon it at levels above those of the lands from which the same stones were derived.* The drift of Berkshire and of New England in general has a great resemblance to the terminal moraines of glaciers, being un- stratified and containing fragments of rock, some angular, others rounded. But the proportion of rounded boulders is far more considerable in the drift than in an ordinary glacier moraine, in which last, as Mr. D. Sharp has lately shown in reference to some Swiss glaciers, the rounded blocks are quite the exception to the rule. Want of stratification is the natural result of the melting of matter out of stationary ice, the light particles and the heavy stones dropping down together, and no current of water sorting the materials, and carrying those of less specific gravity to greater distances. Stones frozen into coast-ice may have been rounded, some by rivers, others by the waves of the sea. The dearth of marine shells is sometimes urged as an argument against the hypothesis of submergence beneath the sea, and it is certainly strange that marine shells should be so rare in drift. They are, however, extremely scarce in parts of New P^ngland, such as Ver- mont and Maine, where a few, nevertheless, do occasionally occur ; and this holds good in Canada, as also in Ireland and other parts of the North of Europe. As we cannot doubt that the formation accu- * C. Darwin, Gcol. Quart. Joum. Vol. VI., p. 315. 1848. Vol. II. H 90 Sir Charles Lyell [April 27, mulated in certain cases under water, we are at liberty to assume the same in all others, where such an explanation will best accord with the facts. The Saxicava rugosa, Mya truncata, Natica clausa, and other recent species of mollusca, are common to the drift of North America and Europe, and constitute part of a fauna, characteristic of a climate somewhat colder than that of the latitudes where the fossils are now met with. The Caplan also, or Mallotus villosus, a fish swarm- ing in the seas of Greenland, Labrador, and wherever ice abounds in the North Atlantic, is found fossil in clayey concretions or clay stones, in the drift of Maine and Canada, as well as in Greenland. It appears that in the glacial period, as now, the isothermal lines, or rather the lines of equal winter temperature bent many degrees farther south on the west than on the east side of the Atlantic, so that the monuments of glacial action extend some eight or ten degrees farther south in North America than they do in Western Europe. Large erratics and glacial furrows are rare south of lati- tude 48^ or 50° in Europe, and are seldom seen south of 40^ in North America ; but where mountain chains like the Alps or Hima- laya have formed independent sources of cold, we find exceptions. In Madeira and the Canary Islands, between latitudes 28^ and 33*^ N., Sir C. Lyell searched in vain for glacial striae, and other con- comitant phenomena, although some of the mountains there are of great height. In the southern hemisphere all the manifestations of the agency of ice, which are wanting in the equatorial zone, reappear in full force, when we reach Chiloe, Patagonia, and Tierra del Fuego. If ice-islands, running aground on the bed of a sea or on a a coast, can smooth and furrow the subjacent floor of the ocean by pushing before them or pressing down under them loose sand, pebbles, and stones, the size of such islands is certainly sufficient to afford as much friction and mechanical force as we require. Some of them, measured in the southern hemisphere, exceed 10 miles in diameter, and their height out of the water is from 100 to 200 feet, the mass of ice below being about eight times in volume that rising above the sea-level ; if such masses when they run aground are moving only at the rate of one or two miles an hour, their momentum must be enormous. The area now subject to the action just alluded to in both hemi- spheres, is many times greater than that over which terrestrial glaciers descend. In like manner, in the period of the " Northern drift,*' the submarine were far more extensive than the supra- marine glacial operations ; and since we have evidence of much sea having been converted into land since the glacial period, we must expect to find more space bearing the imprint of subaqueous ice than of space exhibiting evidence of the movement of ice over dry land. In conclusion, Sir C. Lyell observed, that as the great majority 1 855.] on Trains of Erratic Blocks in Massachusetts. 97 of mankind live now as they have always lived, near the equator, or in countries not more than 25 degrees distant from it, they can never behold ice or snow. We may imagine, therefore, a nation to liave made considerable progress in science without knowing any- thing of the causes appealed to in this discourse. If such a people were told by travellers of the geological appearances above described, how great would be their perplexity ! They might at first ascribe the transport of erratics to floods of extraordinary violence, but they would scarcely be able to hazard a reasonable conjecture in regard to the coincidence between the direction of glacial furrows and that of the trains of erratics. A stone, not held fast by ice, but merely pushed along in mud, could not scoop out a long rectilinear furrow, one inch, or sometimes a foot deep, in a hard rock. Still more mysterious would be the discovery of a connection between the former migration southwards of an arctic fauna, and the conveyance of large erratics to the same regions. If the glacial hypothesis afforded no more than a plausi- ble explanation of the association of so many distinct and indepen- dent classes of phenomena, it would deserve greater favour than has been shown to it by some modern geologists. The inclination evinced by many to introduce catastrophic action, as peculiarly applicable to the case of drift, arises in a great degree from the absence of stratification in drift. The usual geological proof of successive accumulation, and of the lapse of time, is here want- ing ; hence the sudden uplifting and sinking of land, the dis- placement of the sea, and the raising of gigantic waves of translation, rolling over continents at the rate of fifty miles an hour, accompanied by rapid gyrations of the marine fluid, have been imagined. The rate of movement, suggested by the glacial hypo- thesis, is singularly opposed to these views. Blocks carried by glaciers travel for centuries at an average rate of less than an inch per hour, and those borne along by floating ice float a mile or a mile and a half an hour. The observer of icebergs can seldom tell whether their course be north or south, east or west. In like man- ner the submergence and re-emergence of land will best account for the appearances above described, if the movement were slow, as now in Greenland and Scandinavia ; in other words, if it be such as would be insensible to any human inhabitant. Yet the power of the machinery appealed to in both cases is equally vast ; for it must be capable of uplifting and depressing continents, and removing from place to place the great volume of superficial materials found in the drift. The real difference of opinion consists in the amount of time during which the force is supposed to have been developed. [C. L.] B 2 98 Anmial Meeting, [May 1> ANNUAL MEETING, Tuesday, May 1. The Duke of Northumberland, K.G. F.R.S. President, in the Chair. The Annual Report of the Committee of Visitors was read, and adopted. — It states that the Contributions from Members and An- nual Subscribers in 1854 were very satisfactory, as well as the Receipts for attendance at the courses of Lectures. The General Income exceeded the Expenditure of the year by the sum of £795. 2s. 4d. ; and the Managers were enabled, in addition to the annual investment of the Accumulating Funds, amounting to £184. 10^. Id., to lay out £500 in the purchase of £3 per cent. Consols, and to buy an Exchequer Bill for £100. A List of Books Presented accompanies the Report, amounting in number to about 175 volumes, and making a total, with those purchased by the Managers and Patrons, of nearly 900 volumes (including Periodicals) added to the Library in the year. Thanks were voted to the President, Treasurer, and Secretary, to the Committees of Managers and Visitors, and to Professor Faraday, for their services to the Institution during the past year. The following Gentlemen were unanimously elected as Officers for the ensuing year : — President— The Duke of Northumberland, K.G. F.R.S. Treasurer— William Pole, Esq. M.A. F.R.S. Secretary — Rev. John Barlow, M.A. F.R.S. Managers. William H. Blaauw, Esq. M.A. F.S.A. Sir Benjamin Collins Brodie, Bart. D.C.L. F.R.S. John Bate Cardale, Esq. Thomas Davidson, Esq. George Dodd, Esq. F.S.A. Sir Charles Fellows. Sir Henry Holland, Bart. M.D. F.R.S. Henry Bence Jones, M.D. F R.S. George Macilwain, Esq. Right Hon. Baron Parke, M.A. John Percy, M.D. F.R.S. Lieut.-Gen. Sir George Pollock,G.C.B. Alfred S. Taylor, M.D. F.R.S. Aaron Asher Goldsmid, Esq. j Charles Wheatstone, Esq. F.R.S. 1855.] Dr, Gladstone on Gunpowder ^ and its substitutes. 99 Visitors. Henry Browning, Esq. John Charles Burgoyne, Esq. John Robert F. Burnett, Esq. Alexander Crichton, Esq. Hugh W. Diamond, M.D. F.S.A. Edward M. Foxhall, Esq. Thomson Hankey, jun. Esq. M.P. Admiral Sir T. Herbert. K.C.B. M.r. John Hicks, Esq. John Holdship, Esq. M.A. Octavius Morgan, Esq. MP. F.R.S. Robert R. I. Morley, Esq. John North, Esq. Rev. Cyril W. Page. Rev. William Taylor^ F.R.S* The President nominated the following Vice-Presidents for the ensuing yetir : — The Treasurer, the Secretary, Sir B. C. Brodie, Bart., Sir Charles Fellows, Bart., Sir Henry Holland, Bart., Right Hon. Baron Parke, and Sir George Pollock, G.C.B. WEEKLY EVENING MEETING, Friday, May 4. Sir Charles Fellows, Vice-President, in the Chair. Dr. J. H. Gladstone, F.R.S. M.R.I. On Gunpowder, and its substitutes. The object of the speaker was to return an answer to a question which had of late been frequently proposed to him, and no doubt to other chemists also : — " Cannot you now invent something much better than gunpowder ? Are not some of your fulminating com- pounds much more powerful ? Why should we still be using a substance which was discovered long before chemistry was a science ? " Dr. Gladstone stated that some of his friends had considered him peculiarly qualified to give a reply to the query, since he had analyzed in turn the most terrible explosives with which modern science has made us acquainted ; yet he confessed he laboured under a disadvantage in having no practical acquaintance with gunnery, nor even with those experiments by which the pro- pulsive force of different explosives is tested. He could give no categorical answer to the proposed inquiry. He could point to no substance, and say of it — " For use in fire-arms this is decidedly superior to gunpowder ;" nor was he willing to say — " No ; it is beyond the power of our science to invent anything better." He was desirous of laying before the audience some of the principles upon which a judgment might be formed ; of indicating the manner of investigation, as much as the results already arrived at. 100 Dr. J, H. Gladstone [May 4, In so doing he glanced first, in a cursory manner, at the various kinds of explosives with which chemists are acquainted. Any great and sudden increase of volume may give rise to the phenomena designated explosion ; but such great and sudden increase never takes place by the mere dilatation of a solid or liquid body : it is always necessary that gases should be formed. The simplest form of explosion is when a liquid is suddenly converted into a gas either by the removal of pressure, or by the bursting of the vessel in which it was contained, as illustrated by the common " candle-cracker." The enormous expansion of a gas by the removal of pressure is taken advantage of for the projection of missiles in the air-gun, and in Perkins's steam-gun. In these cases there is no chemical change ; but usually an explosion is the result of a rapid chemical action between the different constituents of a mixture, or chemical compound, by which substances are produced that occupy a very much larger space than the original combination did. Such an explosion is always attended with heat, and generally with light and noise. The substance exploded may be a mixture of two or more gases : for instance, if the fire-damp of the mines be set fire to in the air, it burns quietly with a luminous flame ; if, however, it be previously mixed with air, on being ignited the flame passes instantly throughout the whole mass ; and if mixed with twice its volume of oxygen, this takes place with great violence, and a loud report. One atom of the carburetted hydrogen combines with four atoms of oxygen, to form carbonic acid and water. In this case, however, the gases produced by the explosion would actually have occupied less space than the original mixed gases, and a positive contraction would have ensued, had it not been for the high temperature at which they were formed. In order to obtain very great expansion we must not start with a gaseous mixture. Solid or liquid oxygen is a desideratum, but it can be procured in that condition only when in a state of combination. There are several salts which contain a large quantity of this element, and which give it up with great facility — the nitrates and chlorates of potash or soda, for instance ; and these salts contain also another element, which when free assumes a gaseous condition, even at ordinary temperatures. Dr. Gladstone then proceeded to show the violent combustion that ensued when wood was thrown into one of these salts in a fused condition, and to demonstrate the still greater effects that resulted when the salt and the combustible had been previously mixed. He then rapidly described the manufacture of gunpowder from nitre, charcoal, and sulphur, and the different proportions of the three ingredients that are employed in different countries. In exploding, gunpowder produces carbonic acid and nitrogen gases, and sulphuret of potassium, which is also dissipated by the great heat evolved, and if it reach the air is converted into sulphate of potash, giving rise to the white smoke that follows the explosion. Beside these gases some others are always produced in small and varying quantity^ 1855.] on Gunpowder y aiid its substitutes, 101 By burning a fuse under water these gases were exhibited. It is. supposed that, at the moment of explosion, the heated gases occupy fully two thousand times the volume of the original powder. By mixing different combustibles with nitre various effects may be produced on explosion ; sometimes the light, sometimes the heat, and sometimes the noise being the most remarkable. When nitre was an article of scarcity in France, the French chemists made many experiments with a mixture of chlorate of potash, charcoal, and sulphur; but this compound, though a good explosive, has several disadvantages, which have prevented its ever coming into extensive use. A white gunpowder has more recently been pre- pared by mixing chlorate of potash with yellow prussiate of potash and sugar. Tlie explosives hitherto described are all mixtures. There exist substances which contain all the elements of combustion within themselves, and which require only a slight elevation of temperature, or a smart blow, to alter their state of chemical combination, and suddenly to produce gaseous bodies in large quantity. Pre-eminent among these is Gun-cotton : a substance formed by immersing cotton in a mixture of nitric and sulphuric acids. It is generally allowed now that this compound consists of lignine, C24 Hgo O20, in which a portion of the hydrogen has been replaced by NO4 ; differ- ence of opinion exists as to the amount so displaced, but Dr. Glad- stone had found it to be five atoms in the most explosive gun- cotton, three in that of inferior quality, which he designated cotton- xyloidine. The most explosive compound produces a sudden flash, but no smoke or loud noise, and leaves no residue whatever. Hy- drocyanic acid is among the resulting gases. — Nitroglycerine, a liquid produced in a similar manner from glycerine, is of so explo- sive a nature, that if a single drop be struck by a hammer on an anvil it gives rise to a deafening report. Its composition is Ce H5 3 (NO4) Oe* Similar to this is nitromannite, which also explodes on percussion . Several other simple nitric acid substitution products are also capable of explosion ; and so are certain salts of organic acids, which are analogous in their constitution ; for instance, carbazotate of potash. Fulminating mercury and silver are also salts of an organic acid, the fulminic, which contains both oxygen and nitrogen. They explode, as is well known, by percussion, and with extreme violence. There are, however, certain detonating compounds, which contain no oxygen, nor any other supporter of combustion, but which are easily caused to undergo an internal change, and to resolve themselves into gaseous products. The most remarkable of these are certain substitution products of ammonia — the so-called ammoniurets of gold and other noble metals, and the so-called iodide and chloride of nitrogen. The iodide is a black powder, which when dry will explode on the slightest touch of a hard sub- stance, and even sometimes by a sudden concussion of the air near it. Its composition had been examined by the speaker, and found 102 Dr. J. //. Gladstone [May 4, to be always N II I^. The chloride is a still more dangerous sub- stance, since it explodes with the greatest facility under water. It is an oily liquid, discovered simultaneously in 1811, by M. Dulong, in France, and by a young English chemist, Mr. Burton, of Ton- bridge. Dr. Gladstone's analyses gave as its composition Ng H Q\. The qualities requisite to render an explosive practically useful were then considered. This depends, of course, upon the purpose to which the explosive is to be applied. If it be merely for the production of an instantaneous flame in order to ignite some other body, those compounds which are exploded by percussion liave a great advantage. —Percussion caps of various kinds were exhibited — those intended for muskets being filled with a mixture of equal parts of fulminating mercury and chlorate of potash, fixed by a varnish ; those made use of for cannon, being charged with two parts of chlorate of potash, two of native sulphuret of antimony, and one of powdered glass, which last appears to be practically a beneficial ingredient, although it takes no part in the chemical action. Caps made of fulminating mercury and collodion, bronzed over, were also shown. — Explosives, however, are generally intended for the projection of missiles, or for blasting. For either of these purposes propulsive force is the grand requisite. Now most of the compounds previously described explode too rapidly, and produce a very powerful local effect. If employed in fire-arms they would tear or strain the gun, and not propel the ball any great distance. Gunpowder, if tightly compressed, as in a fuse, or a port-fire, burns comparatively slowly ; the necessary rapidity of explosion is given to it by granulation ; and this can be modified according as the different purposes for which it is manufactured require. Supposing an explosive to have the necessary propulsive power, a very important quality is safety- — safety in the process of manufacture, and in its subsequent keeping and handling. This practically excludes the use of all those compounds which are exploded by a blow. Gun- powder requires a temperature of 600° Fah. to ignite it ; and this gives it a great advantage over gun-cotton, which is fired by a heat not much exceeding that of boiling water. — The comparative diffi- culty of exploding gunpowder was exhibited by setting fire to some ether round about a portion of it, which remained unaffected in the middle of the large flame ; and by igniting a piece of gun-cotton without firing the little heap of powder on which it rested. Gun- powder may even be sprinkled on the top of gun-cotton, and the latter may be exploded, and cause the scattering of the black grains unaltered. — It is a desideratum that the explosive should not be injured by wetting. In this respect gunpowder fails, while gun- cotton, and several of the substances previously mentioned, suffer no injury by being soaked in water and dried again. Good gun- powder, however, is not materially affected by the ordinary damp of tlie atmosphere. Nitrate of soda, though it contains a much larger amount by weight of gas-forming constituents, cannot be 1855.] on Gunpowder^ anfl its substitutes. 103 substituted for nitrate of potash in the manufacture of gunpowder, partly because the resulting mixture is hygroscopic. — The complete combustion of an explosive is another desideratum. In firing cannon, a considerable portion of the charge of gunpowder is always lost, by being blown out unburnt ; but this is the case to a much greater extent with gun-cotton, as was experimentally demonstrated. It is important also in respect to fire-arms that the products of combustion should not foul or corrode the piece. Gunpowder leaves a considerable residuum, which has to be sponged out afterwards, but it is an alkaline salt, and has little effect upon metal. Gun-cotton, on the contrary, leaves no residuum; but the piece remains filled with the highly corrosive red nitrous fumes which have an acid reaction. Cheapness is, of course, an im- portant element in comparing the practical value of different explosives ; but the calculation must be made not according to the weight, but according to the propulsive force of the various substances. This review of the qualities requisite in an explosive shows that gunpowder is admirably suited to such a purpose, on account of its great propulsive power with little local strain, its great safety, both in manufacture and in use, and its cheapness. It has two dis- advantages ; its being spoilt if wetted, and its leaving after ex- plosion a quantity of solid matter. It is evident, that most of the fearfully explosive substances, with which chemistry has made us acquainted, are perfectly inapplicable to the projection of balls. Mixtures containing chlorate of potash, though good in some respects, are dangerous. Gun-cotton is the only substance that puts forth just now any great pretensions, as a substitute for gunpowder ; its pro- pulsive force is somewhere about three times that of an equal weight of powder, and it has some other advantages, coupled however with serious disadvantages. The Austrian government has lately put it very fully to the test of experiment ; and that they have been to some extent satisfied of its value, is attested by the fact, that a considerable number of cannon, of great thickness of metal about the breach, have been formed expressly with the object of employing it. It is said to be a modification of gun-cotton which is used ; and the speaker thought it most probably Wiis either a lower substitution product of cotton, or a mixture of ordinary gun-cotton with some other substance. In England, experiments have some- times been made with this material, and it is said to have been employed with advantage for filling shells at the siege of Moultan ; but on account of the many accidents that have occurred with it, it finds little favour at present with our military authorities. Dr. Gladstone concluded, by stating, that though he considered war under any circumstances to be a fearful evil, yet he wished he could point out a still more efficient explosive than gunpowder ; for he believed that to render war a more certain game tended to indispose men to engage in it. lie was glad to be able to state. 104 General Monthly Meeting. [May 7, that the Government had lately organized the means of examining the merits of every suggested improvement, and that the appointed parties were now actively engaged in the investigation. At present there appear two improvements in the art of war, in which chemical science may be of service : the one in making shells, which shall burst upon striking — about which there is no chemical difficulty ; the other in charging shells with substances that will give forth quantities of poisonous gas ; a subject which has lately attracted much attention. It is to be hoped, that not only mechanical, but also chemical science, will soon furnish us with improvements on the present means of carrying on the war in which we are now engaged. [J. H. G.] GENERAL MONTHLY MEETING, Monday, May 7. The Duke of Northumberland, K.G. F.R.S. President, in the Chair. George Ade, Esq., and William Stuart, Esq. were duly elected Members of the Royal Institution. Andrew Whyte Barclay, M.D. was admitted a Member of the Royal Institution. The following Professors were unanimously re-elected : — William Thomas Brande, Esq. D.C.L. F.R.S. L. & E , as Honorary Professor of Chemistry in the Royal Institution. John Tyndall, Esq. Ph.D. F.R.S., as Professor of Natural Philosophy in the Royal Institution. The following Presents were announced, and the thanks of the Members returned for the same : — From Allies, Thomas W. Esq. 31. A. M.R.I, {the Author)— St. Peter, his Name, and his Office, as set forth in the Holy Scriptures. 8vo. 1852. Journal in France, in 1845 and 1848; with Letters from Italy, in 1847. 12mo. 1849. The Royal Supremacy, viewed in reference to the two Spiritual Powers of Order and Jurisdiction. 8vo. 1850. 1855.] General Monthly Meeting. 105 Asiatic Society of Bengal — Journal, No. 245. 8vo. 1854. Astronomical Society, Royal — Monthly Notices. Vol, XV. No. 5. 8vo. 1855. Bell, Jacob, Esq. M.R.t. — Pharmaceutical Journal for April, 1855. 8vo. Boosey, Messrs. (the Publishers) — The Musical World for April, 1855. 4to. Bradbury, Henry, Esq. M.Ji. I. — The Ferns of Great Britain and Ireland. By T. Moore, F.L.S. Edited by J. Lindley, Ph.D. F.L.S. Part 2. Fol. 1855. British Architects, Royal Institute (2/*— Proceedings in April, 1855. 4to. Chemical Society— Quarterly Journal. No. 29. 8vo. 1855. Civil Engineers, Institution o/'— Proceedings in April, 1855. 8vo. East India Company, the Hon. — Rig-Veda-Sanhitd. Ancient Hindu Hymns. Translated by H. H. Wilson, M.A. F.R.S. 2 vols. 8vo. 1850-4. Magnetical and Meteorological Observations at Bombay, in 1851. 4to. 1854. Editors— The Medical Circular for April, 1855. 8vo. The Athenajum for April, 1855. 4to. The Practical Mechanic's Journal for May, 1855. 4to. The Mechanics' Magazine for April, 1 855. 8vo. The Journal of Gas-Lighting for April, 1855. 4to. Deutsches AthenUum for April, 1855. 4to. Faraday, Professor, D.C.L. F.R.S. (the Author) — Experimental Researches in Electricity. Vol. III. 8vo. 1855. Monatsbericht der Konigl. Preuss. Akademie, MUrz, 1855. 8vo. Berlin. Frost, Charles, Esq. F.S.A. {the Author) —'Notices relative to the Early His- tory of Hull. 4to. 1827. Franklin Institute of Pennsylvania — Journal, Vol. XXIX. Nos. 2,3. 8vo. 1855. Graham, George, Esq. Registrar- General — Report of the Registrar-General for April, 1855. 8vo. Highley, Mr. (the Publisher) — Quarterly Journal of Public Health, and Trans- actions of the Epidemiological Society of London. No. 1. 8vo. 1855. Hood, Charles, Esq. F.R.S. (the Author) — A Practical Treatise on Warming Buildings by Hot Water; on Ventilation, &c. 8vo. 1855. King, Arthur J. Esq. {the Author) — How to learn Latin : or Artificial Memory applied to Latin Words. 12mo. 1855. Madras Literary Society — Madras Journal. Nos. 10, 11. 8vo. 1836. Barometrical Sections of India. By E. Balfour, fol. 1853.« Novello, Mr. (the Publisher) — The Musical Times for April, 1855. 4to. Percy, John, M.D. F.R.S. M.R.I. (the Author) — Experimental Inquiry con- cerning the presence of Alcohol in the Ventriclt s of the Brain, after poison- ing by that liquid. 8vo. 1839. Perigat, H. jun. Esq. (the Author) — Perigal's Contributions to Kinematics, Bicircloids, &c. in six sheets. 1854. Photographic Society — Journal, No. 29. 8vo. 1855. Prince, C. Leeson,' Esq. (the Author) — Results of a Meteorological Jouraal kept at Uckfield, Sussex, in 1854. Sheet. Society of Arts — Journal for April, 1855. 8vo. Taylor, Rev.W. F.R.S. 3f.i?./.— Magazine for the Blind, April, 1855. 4to. Wegweiser zur BildungfUr Deutsche Lehrer. Von Adolph Diesterweg. 2 vols. Essen, 1849-50. Vereins zur Beforderung desGewerbfeisses in Preussen, — Verhandlungen, Jan.und Feb., 1855. 4to. Berlin. Weale, John, Esq. (the Publisher) — Rudimentary Treatises. 12mo. : — Manual of the Mollusca. By S. P. Woodward. Part IL 1854. Art of Photography. By Dr. G. C. Halleur. 1854. Form of Ships and Boats. By W. Bland. 1852. Arithmetic, and Key. By J. R. Young. 1853-4. Educational Series. 12mo. History of England. By W. D. Hamilton. Vols. III. and IV. 1854-5. History of Greece. By W. D. Hamilton and E. Lieven. 2 vols. 1854. History of Rome. By E. Lieven. Vol. I. 1864. 106 Mr, Henry Bradbury [May 11, Wcale^ John, Esq. (the Vnhlishcr) — Educational Scries. 12mo. : — Chronology of History, Art, and Literature. Vol. I. 1 854. Dictionary of the English Language. By Hyde Clarke. 1855. Grammar of the Greek Language. By H. C. Hamilton. 1854. Lexicon of the Greek Language. By H. R. Hamilton. Part II. 1853. English-Greek Lexicon. By JI. R. Hamilton. Part I. 1855. Grammar of the Latin Tongue. By T. Goodwin. 1854. Latin-English Dictionary. By T. Goodwin. 1855. French-English, and English-French Dictionary. By A. Elwes. 2 Parts. 1854-5. Italian-English-French Dictionary. By A. Elwes. Part I. 1855. Spanish-English, and English-Spanish Dictionary. By A. Elwes. 1854. Hebrew and English Dictionary and Grammar. By M. H. Bresslau. 1 855. Classical Series. ISmo. (Edited by H. Young.) Greek Delectus. 1854. Xenophon's Anabasis. 2 vols. 1854-5. Select Dialogues of Lucian. 1 855 . Latin Delectus. 1854. Cajsar's Commentaries. 1854. Cornelius Nepos. 1855. Virgil. Part I. 1855. WEEKLY EVENING MEETING, Friday, May 11. Sill CiiAiiLES Fellows, Vice-President, In the Chair. Henry Bradbury, Esq. M.R.I. On Nature-Printing. The Art of Nature-Printing is a method of producing impressions of plants and other natural objects, in a manner so truthful that only a close inspection reveals the fact of their being copies. So distinctly sensible to the touch are the impressions, that it is difficult to persuade those unacquainted with the manipulation, that they are the production of the printing-press. The process, in its applica- tion to the reproduction of botanical subjects, represents the size, form, and colour of the plant, and all its most minute details, even to the smallest fibre of the roots. The distinguishing feature of the process, compared with other modes of producing engraved surfaces for printing purposes, con- sists, firstly, in impressing natural objects — such as plants, mosses, seaweeds, feathers, and embroideries — into plates of metal, causing as it were the objects to engrave themselves by pressure ; and secondly, in being able to take such casts or copies of the impressed plates as can be printed from -at the ordinary copperplate-press. SPECr3ffJE:N' . NATURE PRINTING BraJbiny & Evans . WiitEfiriars , Londar 1855.] on Nature-Printing. 107 This secures, on the one hand, a perfect representation of the characteristic outline of the plant, as well as that of some of the other external marks by which a plant is known, and even in some measure its structure, as for instance in the venation of ferns, and the leaves of flowering plants ; and on the other, affords the means of multiplying copies in a quick and easy manner, at a trifling expense compared to the result obtained — and to an unlimited extent. The great defect of all pictorial representations of botanical figures has consisted in the inability of art to represent faithfully those minute peculiarities by which natural objects are often best distinguished. Nature-Printing has therefore come to the aid of this branch of science in particular, whilst its future development promises facilities for copying other objects of nature, the reproduc- tion of which is not within the province of the human hand to execute ; and even were it possible, it would involve an amount of labour scarcely adequate to the results obtained. Although considered for some years past in various parts of Europe as a new art, the idea is by no means so recent as is supposed : much less is there ground for the Austrians to assert their exclusive right to the priority of the invention, merely on account of the first application of the process in its fullest extent in the Imperial Print- ing-Office at Vienna. Councillor Auer * has not only done this, but he has claimed for Nature-Printing a position to which it has no right : he has com- pared it to the invention of writing and the art of printing ; more- over, he has placed it on an equality with the Galvanoplastics of Jacobi and Spencer, and the Daguerreotype of Daguerre. Valuable as are the results of Nature-Printing, it still has its defects ; it has its limits, and its applications are limited, and care will be required to confine it within the bounds of its capabilities. That an establishment, so renowned for its productions as that at Vienna, unlimited in its command of the resources of science and mechanism, should have been the first to bring any invention con- nected with printing to a practical state of perfection, is not matter to create surprise ; but that it should, in the most unqualified manner, in the name and on the authority of its chief director, claim all the honour of the discovery, is a point that is open to question, and in point of fact is questioned by several private individuals, who, for want of those unlimited resources and opportunities which only government establishments are able to command, were unable to crown their experiments with practical results. Nature-Printing is nothing more than an application of facts worked out by various persons, in different countries, under very different circumstances, and at very different periods ; and by tracing ♦ Vide Denkschriftcn der Kais. Akademie, Wien ; Math .-Nat. Classe. Band V., p. 107 (illustrated by many plates). 108 Mr. Henry Bradbury [May 1 1 , out its history, and detailing the earlier experiments connected with it, Mr. Bradbury hoped to show that he did not put forward per- sonally any claim either to its origin or to its first application ; but, that he spoke as one who, having perceived its value, was desirous to render it an available auxiliary to the printing-press. Nature herself, in her mysterious operations, seems to have given the first hint upon the subject : witness the impressions of Ferns so beautifully and accurately to be seen in the coal-formations. Experiments to print direct from nature were made as far back as about two hundred and fifty years— it is certain that the present success of the art is mainly attributable to the general advance of science, and the perfection to which it has been brought in par- ticular instances. On account of the great expense attending the production of woodcuts of plants in early times, many naturalists suggested the possibility of making direct use of nature herself as a copyist. In the Book of Art, of Alexis Pedemontanus, (printed in the year 1572,) and translated into German by Wecker, may be found the first recorded hint as to taking impressions of plants. At a later period — in the Journal des Voyages, by M. de Mon- coys, in 1650, it is mentioned that one Welkenstein, a Dane, gave instruction in making impressions of plants. The process adopted to produce impressions of plants at this period, consisted in laying out flat and drying* the plants. By holding them over the smoke of a candle, or an oil lamp, they became blackened in an equal manner all over ; and by being placed between two soft leaves of paper, and by being rubbed down with a smoothing-bone, the soot was imparted to the paper, and the impression of the veins and fibres was so transferred. Linnaeus, in his Philosophia Botanica, relates that in America, in 1707, one Hessel made impressions of plants ; and between 1728 and 1757, Professor Kniphof, at Erfurt, who refers to the experiments of Hessel, in conjunction with the bookseller Fiinke, established a printing-ofiice for the purpose. He produced a work entitled Her- barium Vivum [a copy of which was laid before the Members]. The range and extent of his work, twelve folio volumes, and con- taining 1200 plates, corroborates the curious fact of a printing-oflftce being required. These impressions were obtained in a manner very similar, but with the substitution of printer's ink for lamp-black, and flat pressure for the smoothing-bone. A new feature at this time was introduced — that of colouring the impressions by hand, according to Nature — a proceeding which though certainly con- * Although the plants were dried in everj- case, Mr. Bradbury stated, that it was by no means absolutely necessary, as he proved by the simple experi- ment of applying lamp-black or printer's ink to a fresh leaf, and producing a successful impression. 1855.] on Nature-Printing. 109 tributing to the beauty and fidelity of the effect, yet had the dis- advantage of frequently rendering indistinct, and even sometimes totally obliterating, the tender structure and finer veins and fibres. Many persons at the time objected to the indistinctness of such representations and the absence of the parts of fructification ; but it was the decided opinion of Linnaeus, that to obtain a fac-simile of the difference of species was sufficient. Seligmann, an engraver at Nuremberg in 1748, published in folio plates figures of several leaves he had reduced to skeletons. As he thought it impossible to make drawings sufficiently correct, he took impressions from the leaves in red ink, but no mention is made of the means he adopted. Of the greater part he gave two figures, one of the upper and another of the lower side. Even at this early period the idea must have excited much atten- tion ; for it is recorded that Seligmann had announced his intention to give figures of natural objects as magnified by a solar microscope, and that two were to have been published every month. But he died soon after, and a law-suit prevented the prosecution of his work. Two black and twenty-nine red plates of leaves had been already completed, and were published with eight pages of text, in which his coadjutor. Crew, speaks of the physiology of plants, and Seligmann of the preparation of leaf skeletons. The leaves repre- sented on the plates were those of the orange, lemon, shaddock, &c. In the year 1763 the process is again referred to in the Gazette Salutaire, in a short article upon a Recette pour copier toutes sortes de plantes sur papier. About from twenty-five to thirty years later, Hoppe edited his Ectypa Plantarum JRatisbonensium, and also his Ectypa Plan- tarum Selectarum, the illustrations in which were produced in a manner similar to that employed by Kniphof. These impressions were found also to be durable, but still were defective. The pro- duction of impressions could only take place very slowly, as the blacking of the plants with the printer's ball required much time. Rude as the process was, and imperfect the result, it was never- theless found that the figures thus produced were far more character- istic than any which artists could produce. The fault of the method consisted in its limited application and in its incompleteness ; since the fragile nature of the prepared plant, if ever so carefully treated, would admit of but very few copies being taken, and where any great number would have been required, many plants must have been prepared, a circumstance which was in itself a great obstacle. In the year 1809 mention is made in Pritzell's " Thesaurus " of a New Method of taking Natural Impressions of Plants ; and lastly, in reference to the earlier history of the subject, the attention of scientific men was called to an article, in a work published by Grazer, in 1814, on a Netv Impression of Plants. Twenty years afterwards, the subject had undergone remarkable change, not only in the mode of operation to be pursued, but also 110 Mr. Henry Bradbury [May 11, in the result produced, — which consisted in fixing an impression of the prepared plant in a plate of metal by pressure. It appears, on the authority of Professor Thiele, that Peter Kyhl, a Danish goldsmith and engraver, established at Copenhagen, applied himself for a length of time to the ornamentation of articles in silver ware, and the means he adopted were, taking copies of flat objects of nature and art in plates of metal by means of two steel rollers. Various productions in silver of this process were exposed in the Exhibition of Industry held at Charlottenburgh, in May 1833. In a manuscript, written by this Danish goldsmith, entitled The De- scription {with forty -six plates) of the Method to Copy Flat Objects of Nature and Art, dated 1st May, 1833, is suggested the idea of applying this invention to the advancement of science in general. The plates accompanying this description represented printed copies of leaves, of linen and woven stuffs, of laces, of feathers of birds, scales of fishes, and even of serpent-skins. The manuscript contains ample and clear instructions to carry out the method, and a few extracts, in his own words, of the leading features will be perhaps interesting. He thus writes : — " As a correct copy of the productions of Nature and Art must be of great importance, I am delighted to have the honour of sub- mitting to the friends of Art and Science a method I have disco- vered, by which copies of most objects can be taken, impressed into metal plates, and which enables the naturalist and botanist to get representations of leaves, feathers, scales, &c., in a quick and easy way ; and these copies will give all the natural lineaments, with their most raised or sunken veins and fibres ; moreover, the artist can, by means of this invention, make use of Nature's real pecu- liarities for ornamental compositions and productions ; and the merchant can get patterns of delicately woven or figured stuffs, laces, tickens, ribbon, linen, and so forth. " To fix an impression into a plate of copper, zinc, tin, or lead, properly prepared for the purpose, a rolling machine with two polished cylinders of steel is required ; if a leaf quite dried and prepared, is placed between a polished steel plate half an inch thick and a thoroughly heated lead plate with a fine surface, and these two plates with the leaf between be run speedily between the cylinders, the leaf will by the pressure yield its form on the softer lead plate, precisely as it is shaped, with all its natural raised and sunken parts. " I tried many ways to fix the leaf on the plate by some glutinous matter, but it filled the delicate pores and deep parts so much as to render the copies very indistinct.* " The printing itself of the leaf into the metal requires much * Mr. Bradbury stated that he had himself tried this method without success. SJPJhjr'iy/y, \\ V NATURE PRIHTINC BrsiSba^ tr Evans ."Vbttefiriars . London 1855.] on Nature-Printing, HI precaution, especially with respect to placing the cylinders exactly parallel, and at the same time at a proper distance, and to have the plate to be stamped carefully burnished and polished ; besides, the utmost care must be used, as particles of dust or dirt would be printed together with the object itself. Moreover, care must be taken, that the rolling of the plates is managed well, so as to run parallel, without deviating from their first direction. " Leaves that are to be printed must first be spread upon a clean sheet of paper and placed upon a warm oven ; a second sheet put over them is to be strewn with sand, and the whole left to dry under a weight. This done the leaves are taken out with due precaution, and placed for a quarter of an hour into water. They are dried again in the same way, and this manipulation is repeated four or five times. By this means I always found that the leaves gained in tenacity and firmness, that they lost all their moisture, and became more fit to be stamped. Objects, such as laces, weavings, figured ribbons, and such like, can be printed without any prepara- tion, provided they be spread flat between the plates. " The season being very unfavourable for gathering good strong leaves, I had to overcome many difficulties, so that the copies are not so good as they might have been — for I have observed that leaves obtained from green-houses do not yield such distinct prints as those that grow in the open air, when properly developed."* It would appear from the practical hints here given that Peter Kyhl was no novice at the process. lie distinctly points out what he conceives to be its value, by the subjects that he tried to copy ; and he enters into detail on the precautions to be observed in the operation of impressing metal plates so as to ensure successful impressions. His manuscript explains that he had experimented with copper, zinc, tin, and lead plates. Still there existed obstacles which prevented him from making a practical application of his invention. In the case of zinc, tin, and copper, the plant, from the extreme hardness of the metals, was too much distorted and crushed ; while in lead, though the impression was as perfect as could be, there was no means of printing many copies, as it was not possible after the application of printer's ink to retain the polished surface that had been imparted to the lead plate, or to cleanse it so thoroughly as to allow the printer to take impressions free from dirty stains. This was a serious obstacle, which was not compensated for even by the peculiar rich surface of the parts that were impressed, attributable to the lead being more granular than copper, and which is ♦ This allusion to the want of tenacity and firmness in young, and especially in green-house plants, is quite consistent with the experiment made at the present time. Mr. Bradbury stated, that to obtain an impression at all, upon a plate of metal, of a plant, it was indispensable that the plant should be thoroughly dried and free from sap ; otherwise the plant would spread in all directions, without leaving any visible indentation. Objects such as lace, and figured fabrics, can be impressed without any preparation, provided they be spread flat between the plates. Vol. II. I 112 Mr. Henry Bradbury [May 11, so favourable to adding density or body of colour, without obliterating the tender veins and fibres. Peter Kyhl died in the same year that he made known his invention. At his death, his manuscripts and drawings were deposited in the archives of the Imperial Academy of Copenhagen, where they remained for upwards of twenty years : and it is a remarkable fact, that, shortly after his death, was dis- covered the only thing wanting to render the process, as explained by him, at once available for practical purposes. Had Kyhl lived to pro- secute his experiments, he might have accomplished more than he did without requiring the aid of other means.* It was he who discovered how to take impressions in metal plates, by using steel-rollers. This is the first element in the process of Nature-Printing. It fell to Dr. Ferguson Branson, of Sheffield, to suggest the second, and the most important. During the next twenty years Nature- Printing was but indiffer- ently prosecuted by various persons for various purposes. Mr. Taylor, of Nottingham, as far back as 1842, printed lace, &c,, specimens of which were exhibited at the Great Exhibition ; and Mr. Twining, of Nottingham, in 1847, printed ferns, grasses, and plants, which were exhibited by the Botanical Society of London. He adopted the same plans as those used by Kniphof and Hoppe. In 1847, also, Dr. Ferguson Branson commenced a series of experiments, an interesting paper upon which was read before the Society of Arts in 1851, and therein for the first time was suggested the application of that second and most important element in Nature-Printing which is now its essential feature — the application of the Electrotype. " I beg leave," says he, " to bring before the notice of the Society of Arts a new method of engraving plates for printing ferns, leaves, seaweeds, and other flat plants Having taken in gutta- percha some impressions of ferns, the singularly beautiful manner in which the exact character of the plant was transferred to the gum suggested to me the possibility of printing from the gutta-percha itself, so as to produce on paper a facsimile of the plant. That experiment partially succeeded, and curiously tested the elasticity of the substance ; for the impression remained uninjured, after being subjected to the great pressure of a copper-plate roller. I say that it -partially succeeded ; for the printer found it utterly impossible so thoroughly to cleanse the ink from the margin around the im- pression, as not when printed to leave a dirty stain on the paper. The impressions thus produced were very accurate ; but the process was valueless as regards multiplication of the prints.*' It then occurred to Dr. Branson that an electrotype copy would obviate the difficulty. * Kyhl, as it was, had had his attention directed, and had made experi- ments to overcome this one remaining difficulty. His manuscript also contains many interesting and practical remarks upon other processes than simply Nature-Printing. 1855.] on Nature-Printing. 113 He afterwards stated that he abandoned the process of electro- typing in consequence of his finding it tedious, troublesome, and costly, to produce large plates. Having occasion, however, to get an article cast in brass, he was astonished at the beautiful manner in which the form of the model was reproduced in the metal. He determined, therefore, to have a cast taken in brass from a gutta- percha mould of ferns, and was much gratified to see the impression rendered almost as minutely as by the electrotype process ;* but, however curious his individual specimens, the process produced no practical result. In 1849, Professor Leydolt, of the Imperial Polytechnic Insti- tute at Vienna, availed himself of the resources of the Imperial Printing-OfHce to carry into execution a new method he had conceived of representing agates and other quartzoze minerals in a manner true to nature. Professor Leydolt had occupied himself for a considerable period in examining the origin and composition of these interesting objects in geology. In the course of his ex- periments and investigations he had occasion to expose them to the action of fluoric acid, when he found, in the case of an agate, that many of the concentric scales were totally unchanged, while others, to a great extent, decomposed by the acid, appeared as hollows between the unaltered scales. It occurred to Leydolt that the surfaces of bodies thus corroded might be printed from, and copies multiplied with the greatest facility. The simplest mode for obtaining printed copies is to take an impression direct from the stone itself. The surface after having been etched is well washed with dilute hydrochloric acid and dried ; then carefully blackened with printer's ink. By placing a leaf of paperf upon it, and by pressing it down upon every portion of the etched or corroded surface with a burnisher, an impression is ob- tained, representing the crystallised rhomboidal quartz black, and the weaker parts that have been decomposed by the action of the acid white. It requires but a small quantity of ink — and particular care must be exercised in the rubbing down of the impression. This mode is good as far as it goes — but it is slow and uncertain — and incurring a certain amount of risk, owing to the brittle nature of the object ; and the effect produced is not altogether correct, since it represents those portions black that should be white, and those white that should be black. The stone is not sufficiently strong to be subjected to the action of a printing-press ; an exact fac'simile cast, therefore, of it must be obtained, and in such a form as can be printed from. To effect this, the surface of any such stone (previously etched by corrosion) must be extended by imbedding it in any plastic composition that ♦ The casting in brass is a very interesting experiment — but its results cannot be compared with the production of the electrotype. t India-paprr and Chalk-paper are the l)est adapted for the purpose. i2 114 Mr. Henry Bradbury [May 11, will yield a perfectly flat and smooth surface, so that the surround- ing surface of the plastic composition will be exactly level with the surface of the etched stone : all that is necessary now is to prepare the electrotype apparatus, by which a perfect /ac-^imzVe is produced, representing the agate impressed, as it were, into a polished plate of copper. This forms the printing-plate. The ink in this case, as opposed to the mode before referred to, is not applied upon the surface, but in the depressions caused by the action of the acid on the weaker parts ; the paper is forced into these depressions in the operation of printing, which results in producing an impression in relief — a feature that is rather peculiar to the process, as the raised appearance, especially in the case of plants, adds very much to tlieir effect. The impressions printed in this latter manner present far more beautiful and natural representations, since the crystallised quartz are represented white, while the decomposed parts appear hlach. Professor Ley dolt, however, suggests that some corroded stones are better suited sometimes for one method of representation than the other ; and attention should be paid to this while the stones are being exposed to the action of the acid. He considers that important advantages will result to science from the perfect faith- fulness of such representations, and from the facility and incon- siderable expense of their production. Other objects in geology — such as the fossil remains of fishes, plants, and other organic remains — in some cases can be, and have been, copied with unmistakeable resemblance to the original. It is not clear who may have suggested the possibility of creating impressions of these last-named objects, but one thing is beyond a doubt, that the production of them was left entirely to the judgment of Andrew Worring, as was also the case in the production of the agates and other stones. In operating upon this class of objects, it is desirable that the original should be as flat as possible, as the flatter the general surface is, the more successful will be the effect produced. A mould in the first place is taken with gelatine or liquid gutta- percha, the elasticity of which materials are favourable for flattening the mould without distortion when separated from the original, — a mode that is to be preferred to depositing copper direct upon them, since it is very much more easily manipulated and without the slightest risk of damaging the originals, owing to the absence of pressure. This gelatine or gutta-percha mould is rendered metallic or con- ducting in the usual way by the application of plumbago, and copper is deposited until of suflScient thickness to form a printing plate. In 1852, Mr. Aitken, of Birmingham, followed the footsteps of Kyhl in various experiments made by him in Britannia metal. He took impressions of lace, skeleton-leaves, feathers, cfec, in Britimnia metal, for the purpose of ornamentation, in the same way as Kyhl is said to have done in articles of silver. About this 1855.] rni Nature- Printing. 115 period Dr. Branson again made experiments, and endeavoured to bring Nature-Printing into practical operation. He too tried im- pressions on Britannia metal, not altogether with the view of printing direct from such plates, desirable as it would be to dispense with the operation of taking casts — but of transferring impressions to stone; and after printing an impression in some neutral tint, to resort to colouring by hand. (Specimens of this method were lying on the table ; but, on examination, would not bear comparison with the productions of the present time.) In the Imperial Printing-office of Vienna, the first application of taking impressions of lace on plates of metal, by means of rollers, took place in the month of May, 1852 :* it originated in the Minister of the Interior, Baumgartner, having received specimens from London, which so much attracted the attention of the chief Director, that he determined to produce others like them. This led to their using gutta-percha in the same way that Dr. Branson had used it ; but finding this material did not possess altogether the necessary properties, the experience of Andrew Worring induced him to substitute lead, which was attended with remarkable success. Professor Haidinger, on seeing specimens of these laces, and learn- ing the means by which they^had been obtained, proposed the application of the process to plants. The results of these experi- ments,! ^^ well as those of Professor Leydolt above referred to, appeared in the fifth volume of Memoirs of the Imperial Academy, published at Vienna, in 1850. Up to this time, however, in England, notwithstanding the above- mentioned experiments, the discovery had not assumed any practical form ; but there is little doubt that if any of these persons had had the requisite means and appliances it would have been brought to perfection earlier. These consist mainly in the precipitation of metals upon moulds or matrixes by means of electro-galvanic agency. Nature-Printing owes its present success to the electrotype, which was then, and even at the present time is, the only means by which faithful copies can be taken of those delicate fibrous details that are furnished in the examples of the impressions of botanical and other figures in metal. It may be said to be owing to the extensive scale upon which the process of the electrotype is conducted in the Im- perial establishment, that Worring was enabled to render the process of Nature-Printing practically available as a Printing Art. The deposition of metals by galvanic agency, though long known and practised in England, has been considered more as a scientific than a practical mode of casting ; and it is only within the last few years that its value in its manufacturing capabilities has been ♦ The Austrian patent was taken out on the 12th October, 1853, in the name of Andrew Worring. t These consisted of specimens of lace, leaves, plants, mosses, serpent-skins, the wing of a bat, agates, fossils, and petrifactions ; and it is somewhat curious that these examples were similar in character to those chosen by Kyhl. 116 Mr, Henry Bradbury May 11, properly understood. Up to within a short time it has been found uncertain, difficult, tedious, expensive, and requiring great length of time to obtain adequate results from it ; but Mr. Bradbury stated that he had for the last two years devoted his energies to overcome these difficulties, and that his experiments had been attended with many practical advantages in the Art of Printing. On the table before him he had a small electrotype apparatus, by which was pro- duced a perfect electrotype cast of an impressed metal plate before the audience in half an hour.* He stated, that one of his experiments had been crowned with such success that he had reduced the opera- tion of tlie battery and the decomposition trough to so rapid and certain a result as to be able to duplicate the woodcuts contained in a number of the Illustrated London News^ no matter what their number or size, in the short space of twelve hours (ready in every respect for the press), which he stated as his belief was one of the greatest practical accomplishments that had ever been made in any country in this branch of science ; the value of which to the journal in question will be best understood when it is known, that without this or other means (not yet discovered), the production of the requisite number of copies in time for publication would be a mechanical impossibility (so extensive is its circulation) since from one set of engravings there is a limit to the number of impressions that can be printed from one machine in a given time. The mode of printing these electrotype f plates of plants is the same as in ordinary copper-plate printing, where the impression is produced by passing the inked plate with the sheet of paper laid upon it through a pair of rollers, one of which is covered with four or five thicknesses of blanketing, which causes the peculiar raised or embossed appearance of the impression. In such cases, where there are three, four, or more colours, for instance, — as in flowering plants, having stems, roots, leaves, and flowers, — the plan adopted in the inking of the plate is to apply the darkest colour first, which generally happens to be the roots — the superfluous colour is cleaned off, — the next darkest colour, such as perhaps the colour of the stems, is then applied — the superfluous colour of which is also cleared off, — this mode is continued until every part of the plant in the copperplate has received its right colour. In this state, before the plate is printed, the colours in the different parts of the copper look as if the plant was imbedded in copper. By putting the darkest colour in at the beginning, there is less chance of smearing the lighter ones : the printer too is not only ♦ In the afterpart of the evenuig Mr. Bradbury succeeded in producing thin electro-plates of impressed plates in five minutes. f The copper deposited upon moulds by electro-galvanic agency, is pre- cipitated in such inconceivably small atoms, that the defects previously referred to in the surface of the lead plate, arc oX&o faithful h/ copied, but the surface of copper funlikc that of lead) will allow of these defects being removed by the aid of the burnisher, and a polished surface preserved. 1855.] on Nature-Printing, 117 able by this means to blend one colour into another, but to print all the colours at one single impression. T\\e first practical application of Nature-Printing for illustrating a botanical work, and which has been attended with considerable success, is Chevalier Von Ileufler's work, on the Mosses,* collected from the Valley of Arpasch, in Transylvania ; the second, {the first in this country,) is the " Ferns of Great Britain and Ireland," in course of publication, under the editorship of Dr. Lindley, and printed by Messrs. Bradbury and Evans. Ferns, by their peculiar structure and general flatness, are especially adapted to develope the capabilities of the process, and there is no race of plants where minute accuracy in delineation is of more vital importance than the Ferns ; in the distinction of which, the form of indentations, general outline, the exact manner in which repeated subdivision is effected, and most especially the distribution of veins scarcely visible to the naked eye, play the most important part. To express such facts with the necessary accuracy, the art of a Talbot or a Daguerre would have been insufficient until Nature-Printing was brought to its present state of perfection. Mr. Bradbury then adverted to the ingenious and beautiful productions of Felix Abate, of Naples. His Nature-representations consist of sections of wood, in which the grain is admirably repre- sented. He terms his peculiar process Thermography, or the Art of Printing by Heat. The process consists in wetting slightly the surface of the wood of which facsimiles are to be made, with any diluted acid or alkali, and then taking an impression upon paper, or calico, or white wood ; the impression is quite invisible, but by exposing it for a few instants to a strong heat, the impression appears in a more or less deep tone, according to the strength of the acid or alkali. In this way every gradation of brown from maple to walnut is produced ; but for some woods which have a peculiar colour, the paper, &c. is to be coloured, either before or after the impression, according to the lightest shades of the wood. Abate, in his manipulations, also employs the ordinary dyeing process. It is to be hoped that Abate's process may become alike useful to the natural sciences and the decorative arts. Mr. Bradbury stated, in conclusion, that we are indebted to — Kniphof, for the application of the process in its rude state ; Kyhl, for having first made use of steel-rollers ; Branson, for the suggestion of the electrotype ; Leydolt for the remarkable results he obtained in the repre- sentation of flat objects of mineralogy, such as agates, fossils, and petrifactions ; * Specimen Florce Crijptogamcc vallis Arpasch Carpatoe Transylvani ; Con- scripsit Ludovicus Elques de Heufler. Vienna, 1853. Imp. folio. 118 Mr. Lacaiia [May 18, Haidinger, for having promptly suggested the impression of a plant into a plate of metal at the very time the modus operandi had been provided ; Abate, for its application to the representation of different sorts of ornamental woods on woven fabrics, paper, and plain wood; Worring, of the Imperial Printing-Office, Vienna,* for his practical services in carrying out the plans of Leydolt and Haidinger. Nature-Printing may be considered as still in its infancy ; but the results, already obtained in its application, encourage us to expect from continued efforts such further improvements as will place it not least among the Printing Arts. [H. B.] [A great number of specimens of Nature-Printing, in its various applications, were exhibited ; and the different processes referred to by the speaker, were exemplified in the presence of the audience, during and after the discourse, by workmen and apparatus from the establishment of Messrs. Bradbury and Evans.] WEEKLY EVENING MEETING, Friday, May 18. Rev. John Baklow, M.A. F.R.S. Vice-President and Secretary, in the Chair. James Pniur Lacaita, Esq. LL.D. On Dante and the " Divina Commedia** The speaker, after a few preliminary remarks, proceeded to state, that he should not attempt to give an account of the life of Dante, which was so connected with the chief events of his time, that it was impossible to sketch it with any degree of interest, without entering into many details of the mediaeval history of Italy. Carlo Troya, and Count Cesare Balbo, two of the most profound Italian * It is gratifying to know that the services of this gentleman were recog- nised by his Sovereign, who munificently rewarded him with a gift, and like- ■wise the Order of Merit. • v /'/•:/' /MEjr , NATURE PRINTING iry AEvans ."Whitefriars . TiondDu . 1855.] on Dante and the " Divina Commedia.^* 119 historians of this century, whose recent loss their countrymen have so much reason to regret, might be adduced as illustrations of the statement. Troya, by his researches on Dante's life, and on the meaning of the well-known lines — " Infin che '1 Veltro Verr^,, che la far^ morir di doglia." Inf, i. 101-102. was led to write a mediaeval history of Italy ; and Balbo, by a converse process, ended his studies on the mediaeval history of Italy, by writing a life of Dante. There was. an event in that life, however, which he would not omit to notice, as it had a peculiar interest for an English audience. Dante visited, and most probably attended a course of theology at, Oxford. Boccaccio asserts, in some Latin verses, which he addressed to Petrarca, in sending him a copy of the " Commedia" that Dante had been " . . . . Parisios dudum, extremosque Britannos." Boccaccio, who was born in 1313, had certainly heard it from his father, who resided in Paris as a merchant ; and who, being a Florentine, had no doubt known, and perhaps been familiar with, Dante. John, of Serravalle, Bishop of Fermo, in 1416, translated into Latin, and expounded the " Commedia" at the request of Cardinal Amadeo de Saluces, and of the Bishops of Bath and Salis- bury, whom he had met at the Council of Constance. In the pre- face to his translation, which is in MS. in the Vatican library, Serravalle says : " Dantes dilexit Theologiam sacram, in qua diu studuit tarn in Oxoniis in regno Angliae quam Parisiis ;^' and again : " Se injurentute dedit omnibus artibu^ liberalibus, studens eas Padu,ae, Jjononiae, demum Oxoniis et Parisiis" The lines allusive to the murder of the nephew of Henry III., in the church of Viterbo, by Guy de Montfort : — " Mostrocci un* ombra dall' un canto sola, Dicendo, colui fesse in grembo a Dio Lo cor che 'n sul Tamigi ancor si cola." Lif. xii. 118-120. also evidence the same fact ; for they convey an impression that Dante had himself seen the place in which the head of the murdered youth was preserved. His visit to Oxford must have been between 1308 and 1311, when, after leaving the Malaspinas, he went to Paris. The speaker expressed a wish that some one of the sons of that great seat of learning would enquire fully into the subject, to which as yet no attention had been paid, and to the glories of his " Alma Mater," add that of having received within her walls the greatest poet of Christendom. 120 Mr. Lacaita [May 18, A rapid enumeration was then given of the minor works of Dante : — the Vita Nuova ; the Convito ; the Poesie Minori ; the treatise De Monarchia; the treatise De Vulgari £Jloquio ; and several Latin letters. "With regard especially to his minor poems, it was observed that with the exception of a few sonnets, and the ode to Florence, they are modelled on the Proven9al School, and are a mixture of conventional poetry and scholastic theology, which would scarcely be recognised as proceeding from the same author as the Commedia. The speaker proceeded next to the great poem, which was called by Dante La Commedia, a name it preserved in many of the earlier editions till the end of the fifteenth century, when the epithet of " Divina " was added to it. He gave a short account of the different opinions with regard to what may have suggested the idea of the poem, and noticed how Fontanini supposed it had been sug- gested by a novel of the day containing a description of St. Patrick's well ; while Denina would assign a like honour to two French novels of the 12th century ; Gingueneto the Tesoretto of Brunetto Latini ; Villemain to a sermon of Gregory VII., containing the account of a vision of the other world; and Cancellieri and others to the Visione di Frate Alberico, whose original manuscript is still pre- served in the library of the Benedictine Monastery of Monte Casino. He concluded by saying, that the multiplicity of the sources from which it was maintained to have been derived, went only to prove, not that Dante had borrowed the idea from any previous compo- sition, but that the vision was a prevailing form of the literature of the time ; a form which might be said to have been chiefly introduced and made popular by the spurious Gospels of the second century, pretending to give an account of St. Paul's ascent to the third heaven, and by the Pastor of Hermas. It was worthy of remark, that Dante, when only nine years old, on seeing and admir- ing Beatrice, one year younger than himself, wrote a sonnet, which caused him to be favourably noticed by the contemporary poets, except Dante da Maiano, who ridiculed him ; and that the form that his thoughts assume, even at that very early age, is that of a vision or a dream. After alluding to the various controversies which for five centuries had been raised concerning the allegory of the poem, the speaker stated that he adopted Troya. and Balbo's historical explanations of most of the allegorical passages. He pointed out the absurdity of the hidden anti-papal spirit supposed to run through the whole poem ; a theory first hinted by Ugo Foscolo, and afterwards en- larged upon by Gabriele Rossetti. He conceived that Dante was strictly orthodox in his Roman Catholic tenets; and he felt no hesitation in asserting that a learned theological reader might almost consider the Commedia, especially the " Paradiso^' as a poetical synopsis of the Summa Theologica of St. Thomas Aquinas, whose leading tenets were propounded throughout the poem, clothed in 1855.] on Dante and the " Divina Commedia." 121 the most beautiful poetical language, sucli as Dante alone had the power of combining with the scholastic theology. It was the temporal power of the Popes that Dante so constantly attacked, and that in no liidden way, as might be seen by a reference to three beautiful passages in Inf. xix. 46-123, Purg. xvi. 97-132, and Par. xxvii. 1-66. Dante in this respect might be considered a proof that the teaching of Arnaldo da Brescia had taken hold on the Italian minds. Mr. Lacaita then briefly commented on the controversy raised with regard to the orthodoxy of Dante at the time of the Reformation, and the strange decision given by the Pere Hardouin, that La Commedia was the work of a disciple of Wicliff. He afterwards took a rapid survey of the fluctuations of the estimation in which the Commedia had been held at different times ; as a proof of which he noticied that the poem, from 1420 to loOO, had gone through 20 editions ; through 42, from 1501 to 1597 ; through 4, from 1598 to 1727 ; throngh 42, from 1728 to 1800; and through more than 180, from 1800 to 1850. He ascribed the neglect into which it had fallen during the whole of the 16th century to the influence of Spanish rule, and the power of the Inquisition in Italy ; and pointed out how the falling oflf of taste in literature, and even in the Fine Arts in Italy had been, if not consequent upon, at least simultaneous with, such neglect. The poem was well known in England in the 14th and 15th centuries ; passages were quoted in which Chaucer had alluded to, or translated from it. But afterwards the poem seems to have been nearly for- gotten, till attention was again called to it by a first English trans- lation in 1773. A few observations were here introduced on the respective merits of the various English translations ; and Mr. Pollock's recent translation was particularly noticed for its faithful conveyance of the meaning of the original. The speaker after- wards proceeded to say, that it was remarkable that Addison seems to have ignored, if not the existence, at least the great merits of the Commedia, so far, that in his journey to Italy, although he describes several monuments at Ravenna, he does not even allude to the tomb of Dante, which only a few years before his visit had been restored by Cardinal Corsi. It was a curious coincidence that at the revival of the study of Dante in Italy, in the 18th century, Voltaire and the ex-jesuit Bettinelli both agreed, though from different motives, in attacking Dante ; Bettinelli, in his Letiere Virgiliane, went even further than Voltaire, who admitted that the Commedia was, " Un ouvrage bizarre ; mais brillant de beautes naturelles, ou Tauteur s'eleve dans les details au dessus du mauvais gout de son siecle et de son sujet." After warmly contending against the preference sometimes given of the Inferno as the finest part of the poem, a preference explained perhaps by the fact that many never read the Purgatorio and the Paradiso, which nevertheless display, when compared with the In- 122 Mr. Lacaita on the '^Divitia Commedia" [May 18, ferno, finer poetical expression, finer powers of description, more gentle and nobler feelings, and a total freedom from coarseness of allusion : the speaker went on to censure F. Schlegel's assertion that the chief defect of the poetry of Dante is a want of gentle feelings ; he felt sure that the German critic had scarcely glanced at thePwr- gatorio and the Paradiso. He proceeded next to point out what he conceived to be the finest passages in the Purgatorio, which from the 1st to the end of the 31st canto is an almost uninterrupted flow of soft and brilliant poetry. He called particular attention to the beautiful opening of the 1st canto ; to the touching meeting of Casella, ii. 67-133 ; the meeting of Manfredi, iii. ; Buonconte di Montefeltro and La Pia de' Tolommei, v. 88-136 ; the meeting of Virgil with Sordello, and the splendid apostrophe to Italy and to Florence, vi. 58-151 ; and to the whole 8th canto, one of the finest in the poem. In quoting the beautiful lines in praise of the Malaspinas, the speaker mentioned that 520 years after Dante had found hospitality among them, another exile. Carlo Troya, driven away from Naples when Austrian bayonets had suppressed the Neapolitan constitution in 1821, was also hospitably received by a Malaspina, with whom he went wandering through Val di Magra, and collecting the local traditions connected with the residence of Dante in that mountainous district. Mr. Lacaita further referred the audience to the description of sculptures, the story of Trajan and the poor woman, x. 28-96, 121-129 ; Oderisi d'Agubbio, Cimabue, Giotto, and the beautiful lines on worldly fame, xi. 73-117; Sapia from Siena, xiii. 91-154; Guido del Duca, the Val d' Arno, and the Romagna, xiv. 16-126 ; the speech of Marco Lombardo, and the allusion to the temporal power of the Popes, xvi. 67-129; Pope Adrian V., xix. 100-145; Ugo Capeto and Pope Boniface VIII., xx. 43-96 ; Forese de' Donati's praises of his widow, and censure of the Florentine ladies, xxiii. 76-111 ; Foresees mention of his sister Piccarda, Buonagiunta da Lucca, Dante's poetry, &c., xxiv. 1-90 and 145-154; Guido Guinicelli, xxvi. 91-135; Dante's dream, &c. xxvii. 70-142; the terrestrial Para- dise, and meeting of Matelda, xxviii. 1-63 ; the meeting of Beatrice, the parting of Virgil, and reprimand of Beatrice to Dante, xxx. 22-145 ; and the whole canto, xxxi. The speaker regretted that time did not allow him to point out in the same way what he considered to be the finest passages in the Paradiso. After some general remarks on the peculiar character and suggestiveness of Dante's poetry, on the truth and wonderful variety of his similes, on the essentially moral tendency of the whole poem, &c., he concluded by quoting the following passage from a very able essay on Dante by Mr. Church, in the Christian Memembrancer, which embodied, better than he could express by words, his feelings in parting with a subject, to which he felt he could scarcely have done adequate justice. " Those who know the Divina Commedia best, will best know 1855.] Professor Faraday o?i Electric Conduction. 123 how hard it is to be the interpreter of such a mind ; but they will sympathise with the wish to call attention to it. They know, and would wish others also to know, not by hearsay, but by experience, the power of that wonderful poem. They know its austere, yet subduing beauty ; they know what force there is in its free and earnest and solemn verse, to strengthen, to tranquillize, to console. . . . But, besides this, they know how often its seriousness has put to shame their trifling, its magnanimity their fainthearted- ness, its living energy their indolence, its stern and sad grandeur rebuked low thoughts, its thrilling tenderness overcome sullenness and assuaged distress, its strong faith quelled despair and soothed perplexity, its vast grasp imparted the sense of harmony to the view of clashing truths. They know how often they have found, in times of trouble, if not light, at least that deep sense of reality, permanent, though unseen, which is more than light can always give — in the view which it has suggested to them of the judgments and the love of God ! " [J. P. L.] WEEKLY EVENING MEETING, f Friday, May 25. Sib Charles Fellows, Vice-President, in the Chair. Professor Faraday, D.C.L. F.R.S. On Electric Conduction. Since the time when the law of definite electrolytic action was first laid down {Exp, Res. 783-966), it has become a question whether those bodies which form the class of electrolytes, conduct only whilst they are undergoing their proper change under the action of the electric current ; or whether they can conduct also as metals, dry wood, spermaceti, &c. do in different degrees, i. e. without the accompaniment of any chemical change within them. The first kind of conduction is distinguished as the electrolytic ; the trans- ference of the electric force appearing to be essentially associated with the chemical changes which occur : the second kind may be called conduction proper ; and there the act of conduction leaves the body ultimately as it found it. Electrolytic conduction is closely associated with the liquid state, and with the compound 124 Professor Faraday [May 25, nature and chemical proportions of the bodies in which it occurs ; and it is considered as varying in degree {i. e. in facility) with the affinities of the constituents belonging to these bodies ; tiiere are, however, other circumstances which evidently, and indeed very strongly affect the readiness of transfer, such as temperature, the presence of extraneous matters, &c. Conduction proper differs as to facility by degrees so far apart, that that quantity of electricity which could pass through a hundred miles of one substance, as copper, in an inappreciably small portion of time, would require ages to be transmitted through the like length of another sub- stance, as shell-lac ; and yet the copper with its similars offers resistance to conduction ; and the lac, and its congeners, conduct. The progress and necessities of science have rendered it important within the last three or four years, and especially at the present moment, that the question " whether an electrolyte has any degree of conduction proper " should be closely considered, and the experiments which are fitted to probe the question have been carried to a very high degree of refinement. Buff",* by employing the electric machine, and Wollaston terminals, i. e. platinum wires sealed into glass tubes, and having the ends only exposed, has decomposed water by a quantity of electricity so small that it required four hours to collect gas enough to fill a little cylinder only -j^L-th of an inch in diameter, and the yth of an inch in length ; yet the decomposition was electrolytic and polar ; and therefore the conduction was electrolytic also. When one pole only was in the water, and the other in the air over it, still the decomposition, and therefore the conduction, was electrolytic ; for one element appeared at the pole in the water, and the other in the air or gas over the water at the corresponding pole. Buff" concludes that electrolytes have no con- duction proper. Many other philosophers have supported, with more or less conviction, the same view, and believe that electrolytic conduction extends to, and includes cases, which formerly were supposed to depend upon conduction proper. Soret advances certain experimental results, "f but reserves his opinion from being absolute. Von Breda and Logeman adopt the more general view unreservedly. J De la Rive, I think, admits that a very little may perhaps pass by conduction proper, but that electrolytic conduction is the function of electrolytes.§ Matteucci has at one time admitted a little con- duction proper, but at present, I believe, denies that any degree exists. On the other hand, Despretz,|| Leon Foucault,1[ Masson,** and myself, have always admitted the possibility that electrolytes possess a certain amount of conduction proper — small indeed, but not so small as to prevent its being evident in certain forms of experiments : * MS. letter. f Annales de Chimie, xlii. 257. % Phil. Mag. viii. 465. § Bibl. de Geneve, xxvi. 134, 144 ; xxvii. 177. || Comptes Rendus, xxxviii. 897. \ Comptes R., xxxvii. 580 ; or Bibl. de Geneve, xxiv. 263 ; xxv. 180 ; xxvi. 126. *♦ Prize Essay, Haarlem Trans., xi. 78. 1855.] on Electric Conduction. 125 and beautiful and close as the electrolytic proofs have been carried, they are not by us considered as sufficient to show that the function of conduction proper is altogether absent from electrolytes. (SomQ account was then given of the experiments and arguments on both sides ; and of the striking electrolytic fact, that if a current of electricity, however small, is sent through a circuit containing a couple of platina plates in dilute sulphuric acid, the plates are found thereby electrically polarized.) The enquiry as regards electrolytes takes on three forms. Tliey may possess a degree of conduction proper at all times — or they may be absolutely destitute of conduction proper— or they may possess conduction proper up to a certain condition, governed either by requisite intensity for electrolyzation or by other circumstances, but which, when that condition is acquired, changes into electrolytic conduction ; and these three forms may be further varied by con- siderations dependent upon the physical state of the electrolyte, as whether it be solid or liquid, hot or cold, and whether it be pure or contain other substances mingled with it. From the time when the question was raised by myself, twenty years ago, to the present day, I have found it necessary to suspend my conclusions ; for close as the facts have in certain cases been urged by those who believe they have always obtained decompo- sition results, when an electrolyte has performed the part of a conductor, and freely as I could have admitted the facts and the conclusions if there had been no opposing considerations, still, because there are such considerations, I am obliged to reserve my judgment. In the first place all bodies not electrolytic, even up to gases (Becquerel,) are admitted to possess conduction proper ; a j^riori, tlierefore, we have reason to expect that electrolytes will possess it also. If from amongst different bodies we retain for con- sideration the class of electrolytes only, then though the amount of electricity of a given intensity which these can transmit electrolyti- cally when they are Jiuid, is often almost infinitely greater than that which they can convey onwards by conduction proper, when they are solid; still the 'conduction in the latter cases is very evident. A piece of perfectly dry solid nitre, and of many other electrolytes, discharges a gold leaf electrometer very freely, and I believe by the power of conduction proper ; and that being the case, I do not see that the assumption of the very highest con- dition of electrolytic conduction when the nitre is rendered fluid is any argument for the absolute disappearance of the conduction proper which belonged to the body in the solid state, though it may override the latter for the time and make it insensible. These considerations are, however, such as arise rather from the absence of the final and strict proof on the opposite side, than from any thing very positive in their own character ; but it has occurred to me that the phenomena of static electricity will furnish us with many reasons of a positive nature, in favour of the possession by 126 Professor Faraday [May 25, liquid electrolytes of the power of conduction proper. Some of these I will endeavour briefly to state, illustrating the subject by a reference to water, which in its pure state has but a low degree of electrolytic conduction. The ordinary phenomena of static charge and induction are well known. If an excited glass rod or other body be held near a light gilt sphere, suspended from the hand by a metal thread, the in- ductive action disturbs the disposition of the electricity in the sphere, and the latter is strongly attracted : if in place of the sphere a soap bubble be employed, the same results occur. If a dish filled with pure distilled water be connected with the earth by a piece of moist bibulous paper, and a ball of excited shell-lac be suspended two or three inches above the middle of the water, — and if a plate of dry insulating gutta-percha, about eight inches long and two inches wide, have its end interposed between the water and the shell-lac, it may then be withdrawn and examined, and will be found without charge, even though it may have touched the shell- lac ; but if the end once touch the water under the lac (and it may be dipped in,) so as to bring away a film of it, charged with the electricity the water has acquired by the induction, it will be found to possess, as might be expected, a state contrary to that of the inductric shell-lac. In order to exclude any conducting body but water from what may be considered as a reference experiment, two calico globular bags with close seams were prepared ; and being wetted thoroughly with distilled water, were then filled with air by means of a fine blow-pipe point ; they were then attached to two suspending bands of gutta-percha, by which they were well insulated, and being about three inches diameter they formed, when placed in contact, a double system six inches in length. A metallic ball, about four inches in diameter, was connected with the electric machine to form an induc- tric body, an uninsulated brass plate was placed about nine inches off to form an inducteous body ; between these the associated water balls could be placed so as to take part in the induction, and when the electric charge was so low that the moist atmosphere caused no transmission of electricity, the balls could be introduced into position and brought away without having received any permanent charge. Under these circumstances if the associated balls were brought into the place of induction, were then separated, withdrawn, and ex- amined, they were found, the one charged positively and the other negatively, by electricity derived from themselves, and without conductive or convective communication with any other substance than their own water. It is well known indeed that by the use of water we may replace metal in all electro-static arrangements, and so form Leyden jars, condensers, and other induction apparatus, which are perfect in principle though with imperfect action. The principles are the same, whether water or metals be used for conductors, and the 1855.] on Electric Conduction. 127 function of conduction' is essential to all the results ; therefore con- duction cannot be denied to the fluid water, which in all such cases is acting as the only conductor. In nature, indeed, the phenomena of induction, rising up to iheir most intense degree in the thunder- storm, are almost, if not altogether, dependent upon the water which in the earth, or the clouds, or the rain, is then acting by its conduct- ing power ; and if this conducting power be of the nature of con- ductio7i proper, it is probable that that function is as large and as important as any exercise of the electrolytic conduction of water in other natural phenomena. But it may be said that all these cases, when accompanied by conduction, involve a corresponding and proportionate electrolytic effect, and are therefore cases of electrolytic conduction ; and it is the following out of such a thought that makes me think the results prove a conduction proper to exist in the water. For suppose a water bubble to be placed midway between a positive and a nega- tive surface, as in the figure, then the parts at and about p will become charged positive, and those at and about n negative, solely by the disturbance of the electric force originally in the bubble, i. e. without any direct transmission of the electric force from N or P ; the parts at c or 5' will have no electric charge, and from those parts to p and n the charge will rise gradually to a maximum. The electricity which appears at p, n, and elsewhere, will have been conducted to these parts from other parts of the bubble ; and if the bubble be replaced by two hemispheres of metal, slightly separated at the equatorial parts e g, the electricity (before conducted in the continuous bubble,) will then be seen to pass as a bright spark. Now the particles at any part of the water bubble may be considered under two points of view, either as having had a current passed through them, or as having received a charge ; in either view the idea of conduction proper supplies sufficient and satisfactory reasons for the results ; but the idea of electrolytic con- duction seems to me at present beset with difficulties. For consider the particles about the equator e q, they acquire no final charge, and they have conducted, as the action of the two half spheres above referred to show ; and they are not in a state of mutual tension, as is fully proved by very simple experiments with the half hemi- spheres. Therefore oxygen must have passed from c towards n, hydrogen from e towards p, i. e, towards and to the parts to which the electricity has been conducted, for without such transmission of Vol. II. K 128 Professor Faraday - [May 25, the anions and cations there would be no transmission of the elec- tricity, and so no electrolytic conduction. But then the questions arise, — Where do these elements appear ? is the water at n oxygen- ated, and that about p hydrogenated ? apd may the elements be at last dispersed into the air at these two points, as in the case of decompositions against air poles? {Exp. Res. 455, 461, &c.) In regard to such questions other considerations occur respecting the particles about p and n, and the condition of charge they have acquired. These have received the electricity which has passed as a current through the equatorial parts, but they have had no current or no proportional current through themselves — the conduction has extended to them but not through them ; no electricity has passed for instance through the particle at n or at p, yet more electricity has gone by some kind of conduction to them than to any other of the particles in the sphere. It is not consistent with our under- standing of electrolytic conduction to suppose that these particles have been charged by such conduction ; for in the exercise of that function it is just as essential that the electricity should leave the decomposing particle on the one side, as that it should go to it on the other : the mere escape of oxygen and hydrogen into the air is not enough to account for the result, for such escape may be freely permitted in the case of electrodes plunged into water ; and yet if the electricity cannot pass from the decomposing particles into the electrodes, and so away by the wires, in a condition enabling it to perform its full equivalent of electric work any where else in the circuit, there is no decomposition at the final particles of the elec- trolyte, nor any electrolytic conduction in its mass. Even in the air cases above referred to there is a complete transmission of the elec- tricity across the extreme particles concerned in the electrolysis. If the above reasoning involve no error, but be considered suffi- cient to show that the particles at p and n are not electrolyzed, then it is also sufficient to prove that none of the particles between p and n have been electrolyzed ; for though one at e or q may have had a current of electricity passed through it, it could not give up its elements unless the neighbouring particles were prepared to take them in a fully equivalent degree. To stop the electrolysis at n and /?, or at those parts of the surface where the moving electricity stops, is to stop it at all the intervening parts according to our present views of electrolysis, and to stop the electrolysis is to shut out electrolytic conduction ; and nothing at present remains but conduction proper, to account for the very manifest effects of con- duction which occur in the case. It may be imagined that a certain polarized state of tension occurs in these cases of static induction, which is intermediate between it and electrolytic conduction {Exp. Res. 1164); or that a certain preparatory and as it were incomplete condition may be assumed, distinguishing the case of static conduction with globes of water, which I have taken as the ground of consideration from the same 1855.] on Electric Conductimi. 129 case when presented by globes of metal. Our further and future knowledge may show some such state ; but in respect of our present distinctive views of conduction proper and electrolytic conduction, it may be remarked that such discovery is just as likely to coincide with the former as with the latter view, though it most probably would alter and correct both. Falling back upon the consideration of the particles between € and n, we find, that whether we consider them as respects the current which has passed through them, or the charge which they have taken, they form a continuous series ; the particle at e has had most current, that at n none, that at r a moderate current ; and there are particles which must have transmitted every intermediate degree. So with regard to charge ; it is highest at w, nothing at c, and every intermediate degree occurs between the two. Then with respect to these superficial particles, they hold all the charge that exists, and therefore all the electricity which has been con- ducted is in them ; consequently all the electrolytic results must be there ; and that would be the case, even though for the shell we were to substitute a sphere of water. For, if those particles which have had more current through them than others be supposed to have more of the electrolytic results about them than the others, then that electricity which is found associated chiefly, if not altogether, with these others, could have reached them only by conduction proper, which for the moment is assumed to be non- existent. So, to favour the electrolytic argument, we will consider the conduction as ending at, and the electrolytic results as summed up in, these superficial particles, passing for the present the former objection that though the electricity has reached, it has not gone through, these particles. Taking, therefore, a particle at r, and con- sidering its electrolytic condition as proportionate to the electricity which has arrived at that particle, and given it charge, we may then assume, for we have the power of diminishing the inductive action in any degree, that the electricity, the conduction of which has ceased upon the particle that was there has been just enough to decompose it, and has left what was the under but is now the surface particle, charged. In that case, some other particle, in a higher state of charge, and nearer to w, as at s, will have had enough electricity conducted towards its place to decompose two particles of water ; — but it is manifest that this cannot be the next particle to that at r, but that a great number of other particles in intermediate states of charge must exist between r and s. Now the question is, how can these particles become intermediately charged by virtue of electrolytic conduction only ? Electrolytic action is definite, and the very theory of electrolytic conduction assumes that the particles of oxygen and hydrogen as they travel convey not a variable but a perfectly definite amount of power onward in its course, which amount they cannot divide, but must take at once from a like particle, and give at once to another like particle. How k2 i30 Professor Famday [May 25, then can any number of particles, or any action of such particles carry a fraction of the force associated with each particle ? It is no doubt true, that if two charged particles can throw their power either on to one, or to three or more other particles, then all the difficulty disappears. Conduction proper can do this : but, as we cannot conceive of a particle half decomposed, so I cannot see how this can be performed by electrolytic conduction, i.e. how the particle between r and s can be excited to the intermediate and indefinite degree, conduction without electrolysis being denied both to it and tlie particles around it. If the particles between e and n be supposed to conduct electro- lytically by the current which passes through them (dismissing for a time, amongst other serious objections, that already given that the products would not be found at the places to which the electricity has been conveyed) still the present argument would have like force. At r enough electricity may have passed through to decora- pose two particles of water, at s only enough to decompose one, — how is a particle between r and s to change elements with the par- ticles either towards r or towards 5, if electrolytic change only is to be admitted ? or how, as before enquired, can two particles throw their power on to, or receive their power from one ? Many other considerations spring out of the thought of a water bubble, under static induction ; but these just expressed, with those that relate to the seat of electrolytic action, whether at the place of current or of charge, create a sum of difficulty fully sufficient, without any others, to make me suspend for the present any conclusions on the matter in question. The conduction power of water may be considered under another point of view; namely, that which has relation to the absolute charge that can be given to the fluid. A point from the electrical machine can charge neighbouring particles of air, and they issue off in streams. It can do the same to particles of camphine, or oil of turpentine ; — it can do the same to the particles of water ; and if two fine metallic wires connected with RuhmkodTs apparatus, be immersed in distilled water, about half an inch apart, the motes usually present will soon show how the water receives charge, and how the charged water passes off in streams, which discharge to each other in the mass. Now such charge is not connected with electro- lysis ; the condition of electrolyzation is that the electricity pass through the water and do not stop short in it. The mere charge of the water gives us no idea where any constituents set loose by electro- lysis can be evolved, and yet conduction is largely concerned in the act of charging. A shower of rain falls across a space in the atmo- sphere subject to electric action, and each drop becomes charged ; spray may be thrown forth from an electrified fountain very highly charged ; — conduction has been eminently active in both cases, but I find it very difficult to conceive how that conduction can be electrolytic in its character. 1855.] on Electric Conduction. 131 When drops of water, oppositely electrified, are made to approach each other, they act by convection, i. e. as carriers of electricity ; when they meet they discharge to each other, and the function of conduction is for the time set up. When the water bubble, described p. 5, is taken out of the sphere of induction, the opposite electricities about p and n neutralize each other, being conducted through the particles of the water. Are we to suppose in these cases that the conduction is electrolytic ? if so, where are the con- stituents separated, and where are they to appear ? It must be a strong conviction that would deny conduction proper to electrolyte* in these cases ; and if not denied here, what reason is there ever to deny it absolutely. The result of all the thought I can give to the subject is a sus- pended judgment. I cannot say that I think conduction proper is as yet disproved in electrolytes ; and yet I cannot say that I know of any case in which a current, however weak, being passed by platinum electrodes across acidulated water does not bring them into a polarized condition. It may be that when metallic surfaces are present, they complete by their peculiarities the condition necessary to the evolution of elements, which, under the same degree of electrification would not be evolved if the metals were away ; and, on the other hand, it also may be that after the metals are polarized, and a consequent state of reactive tension so set up, a degree of con- duction proper may occur between them and the electrolyte simul- taneously with the electrolytic action. There is now no dcubt that as regards electrolysis and its law, all is as if there were but electro- lytic conduction ; but, as regards static phenomena (which are equally important) and the steps of their passage into dynamic effects, it is i)robable that conduction proper rules with electro- lytes as with other compound bodies : for it is not as yet disproved, is supported by strong presumptive evidence, and may be essential. Yet so 'distant are the extremes of electric intensity, and so infinitely different in an inverse direction are the quantities that may and do produce the essential phenomena of each kind, that this separation of conductive action may well seem perfect and entire to those whose minds are inclined rather to see conduction proper replaced by electrolytic conduction, than to consider it as reduced, but not destroyed ; disappearing, as it were, for electricity of great quantity and small intensity, but still abundantly sufficient for all natural and artificial phenomena, such as those described, where in- tensity and time both unite in favouring the final results required. But we must not dogmatise on natural principles, or decide upon their physical nature without proof; and, indeed, the two modes of electric action, the electrolytic and the static, are so different yet each so important, the one doing all by quantity at very low intensity, the other giving many of its chief results by intensity with scarcely any proportionate quantity, that it would be dangerous to deny too hastily the conduction proper to a few Ci\ses in static 132 Professor Tyndall [June 1, induction, where water is the conductor, whilst it is known to be essential to the many, only because, when water is the electrolyte employed, electrolytic conduction is essential to every case of electrolytic action. [M. F.] WEEKLY EVENING MEETING, Friday, June 1. The Duke op Northumberland, K.G. F.R.S. President, in the Chair. Professor Tyndall, F.R.S. On the Currents of the Ley den Battery. In our conceptions and reasonings regarding the forces of nature we perpetually make use of symbols, which, when they possess a high representative value, we dignify with the name of theories. We observe, for example, heat propagating itself through a bar of metal, and help ourselves to a conception of the process by com- paring it with water percolating through sand, or travelling by capillary attraction through a lump of sugar. In some such way • we arrive at what is called the material theory of heat. The thing seen is thus applied to the interpretation of the thing unseen, and the longing of the human mind to rest upon a satisfactory reason, is in some measure satisfied. So also as regards the subject of the present evening's discourse ; we are not content with the mere facts of electricity ; we wish to look behind the fact, and prompted by certain analogies we ascribe electrical phenomena to the action of a peculiar fluid. Such conceptions have their advantages and their disadvantages ; they afford peaceful lodging to the intellect for a time, but they also circumscribe it ; and by and by, when the mind has grown too large for its mansion, it often finds a difficulty in breaking down the walls of what has become its prison instead of its home. Thus, at the present day, the man who would cross the bounds which at present limit our knowledge of electricity and magnetism finds it a work of extreme difficulty to regard facts in their simplicity, or to rid them of those hypothetical adornments with which common consent has long invested them. But though such is the experience of the earnest student of Natural Philosophy at the present — though he may be compelled to refuse his assent to the prevalent theoretic notions, he may never- 1855.] on the Currents of the Ley den Battery. 133 theless advantageously make use of the language of these theories in bringing the facts of a science before a public audience ; and in speaking of electricity, the speaker availed himself of the convenient hypothesis of two fluids, without at all professing a belief in their existence. A Leyden jar was charged. The interior of the jar might be figured as covered with a layer of positive electricity, and the exterior by a layer of negative electricity ; which two electricities, notwithstanding their mutual attraction, were prevented from rushing together by the glass between them. When the exterior and interior coating are united by a conducting body, the fluids move through the conductor and unite ; thus producing what is called an electric current. The mysterious agent which we darkly recognise under this symbol is capable of producing wonderful effects ; but one of its most miraculous characteristics is its power of arousing a transitory current in a conductor placed near it. The phenomena of voltaic induction are well known ; and it is interest- ing to inquire whether frictional electricity produces analogous phenomena. This question has been examined by Dr. Henry, and still more recently by that able and experienced electrician M. Riess, of Berlin. The researches of these gentlemen constituted the sub- ject of the evening's discourse. A wooden cylinder was taken, round which two copper wires, each 75 feet in length, were wound ; both wires being placed upon a surface of gutta-percha, and kept perfectly insulated from each other. The ends of one of these wires were connected with a universal discharger, whose knobs were placed within a quarter of an inch of each other ; when the current of a Leyden battery was sent through the other wire, a secondary current was aroused in that connected with the discharger, which announced itself by a brilliant sjiark across the space separating the two knobs. The wires here used were covered externally with a sheet of gutta-percha ; and lest it should be supposed that a portion of the electricity of the battery had sprung from one wire to the other, two flat disks were taken. Each disk contained 75 feet of copper wire, wound in the form of a flat spiral, the successive convolutions of which were about two lines apart. One disk was placed upon the other one, the wire being so coiled that the convolutions of each disk constituted, so to say, the impress of those of the other, and the coils were separated from each other by a plate of varnished glass. The ends of one spiral were connected with the universal discharger, between whose knobs a thin platinum wire, ten inches long, was stretched. When the current of the Leyden battery was sent through the other spiral, the secondary current, evoked in the former, passed through the thin wire, and burnt it up with brilliant deflagration. A pair of spirals were next placed six inches apart, and a battery was discharged through one of them ; the current aroused in the other was sufficient to deflagrate a thin platinum wire four inches in length. 134 Professor Ty?idall [June I, We have every reason to suppose that the secondary current thus developed is of the same nature as the primary which produced it ; and hence we may infer, that if we conduct the secondary away and carry it through a second spiral, it, in its turn, will act the part of a primary, and evoke a tertiary current in a spiral brought near it. This was illustrated by experiment. First, two spirals were placed opposite to each other, through one of which the cur- rent of the battery was to be sent ; the other was that in which the secondary current was to be aroused. The ends of the latter were connected by wires with a third spiral placed at a distance, so that when the secondary current was excited it passes through the third spiral. Underneath the latter, and separated from it by a sheet of varnished glass, was a fourth spiral, whose two ends were connected with the universal discharger, between the knobs of which a quantity of gun-cotton was placed. When the battery was discharged through the first spiral, a secondary current was aroused in the second spiral, which completed its circuit by passing through the third spiral : here the secondary acted upon the spiral underneath, developed a tertiary current which was sufficiently strong to pass between the knobs, and to ignite the gun-cotton in its passage. It was shown that we might proceed in this way and cause the tertiary to excite a current of the fourth order, the latter a current of the fifth order, and so on ; these children, grandchildren, and great grandchildren of the primary being capable of producing all the effects of their wonderful progenitor. The phenomena of the extra current, which exists for an instant contemporaneously with the ordinary current in a common voltaic spiral, were next exhibited ; and the question whether a spiral through which a Leyden battery was discharged exhibited any similar phenomena was submitted to examination. It was proved, that the electric discharge depended upon the shape of the circuit through which it passed : when two portions of such a circuit are brought near each other, so that the positive electricity passes in the same direction though both of them, the effect is that the discharge is weaker than if sent through a straight wire : if, on the contrary, the current flow through both portions in opposite directions the discharge is stronger than if it had passed through a straight wire. A flat spiral was taken, containing 75 feet of copper wire ; one end of the spiral was connected with a knob of the universal discharger, and the other knob was connected with the earth : between the knobs of the discharger about four inches of platinum wire were stretched ; on connecting the other end of the spiral with the battery a discharge passed through it of such a strength that it was quite unable to raise the platinum wire to the faintest glow. The same length of copper wire was then bent to and fro in a zigzag manner, so that on every two adjacent legs of the zigzag the current from the battery flowed in opposite directions. Wiien these 75 feet of wire were interposed between the battery and the platinum wire, a discharge 1855.] on tJte Currents of the Ley den Battery. 135 precisely equal to tliat used in the former instance, raised the plati- num wire to a high state of incandescence, and indeed could be made to destroy it altogether. When a primary and a secondary spiral are placed opposite to each other, a peculiar reaction of the secondary upon the primary is observed. If the ends of a secondary (50 feet long) be connected by a thick wire, the effect upon the primary current is the same as when the ends of the secondary remain wholly unconnected. If the ends of the secondary be joined by a long thin platinum wire, the reaction of the secondary is such as to enfeeble the primary. This enfeeblement increases up to a certain limit as the resistance is increased, from which forwards it diminishes until it becomes insen- sible. This would appear to prove that to react upon the primary the secondary requires to be retarded ; and that the greater the amount of the retardation, up to a certain limit, the greater is the enfeeblement. But by increasing the resistance we diminish the strength of the secondary, and when a certain limit is attained, this diminution is first compensated for by the influence of retardation, from which point forwards with every increase of the resistance, the enfeeblement of the primary is diminished. A primary current which fuses a certain length of platinum wire where the ends of the secondary are disunited, or where they are united by a thick wire, fails to do so when they are united with a thin wire. Biit if, instead of a thin wire, a body of much greater resistance, a column of water for example, be introduced, the platinum wire is fused as before. [J. T.] 136 Genet al Monthly Meeting. [June 4, GENERAL MONTHLY MEETING, Monday, June 4. The DuitE of Northumberland, K.G. F.R.S. President, in the Chair. J. S. Coleman, Esq. Will. De Lannoy, Esq. George H. In gall, Esq. Col. William Kirkman Loyd. R. Bentley Todd, M.D. F.R.S. were duly elected Members of the Royal Institution. George Ade, Esq. was admitted a Member of the Royal Institution. The following Presents were announced, and the thanks of the Members returned for the same ; — From Administration of the Mines of jRussia — Compte Rendu Annuel, 1853, Par A. T. Kupffer. 4to. St. Petersburg. 1854. Asiatic Society of Boigal— Journal, No. 246. 8vo. 1855. Astronomical Societi/, Foyal— Monthly "Notices. Vol. XV. No 6. 8vo. 1855. Bell, Jacob, Esq, M.R.i. — Pharmaceutical Journal for May, 1855. 8vo. Blashfield, J. M. Esq. M.R.I, (the Author) — History and Manufacture of Terra-Cotta, Ancient and Modem. 8vo. 1855. Boosei/, Messrs. {the Publishers)— The Musical World for May, 1855. 4to. British Architects, Royal Institute o/"— Proceedings in May, 1855. 4to. Civil Engineers, Institution ©/'—Proceedings in May, 1855, 8vo. Dilke, C. Wentworth, Esq. {the Author) — Catalogue of a Collection of Works on, or having reference to, the Exhibition of 1851, in the possession of C. W. Dilke. 8vo. 1855. Editors — The Medical Circular for May, 1855. 8vo. The Practical Mechanic's Journal for May, 1855. 4to. The Journal of Gas-Lighting for May, 1855. 4to. The Mechanics* Magazine for May, 1855. Svo. Deutsches Athenaum for May, 1855. 4to. The Athenaeum for May, 1855. 4to. Faraday, Professor, D.C.L. F.R.S. — Monatsbericht der Konigl. Preuss. Aka- demie, fiir April, 1855. 8vo. Berlin. Whitelocke, B. — Journal of the Swedish Ambassy in 1653-4, from the Com- monwealth of England, Scotland, and Ireland, written by the Ambassador, the Lord Commissioner Whitelocke. 2 vols. 4to. 1762. Shermann, A. J. — Historia Collegii Jesu Cantabrigiensis, edidit et notis instruxit J. O. Ilalliwell. 8vo, 1840. 1855.] General Monthly Meeting. 137 Faraday, Professor^ D.C.L. F./?.S— Sedgwick, A. — Discourse on the Studies of the University. 8vo. 1834. Jardine, G. — Outlines of Philosophical Education. 8vo. Glasgow, 1818. Deleuze, J. P. F. — Eudoxe : Entretiens sur I'Etude des Sciences, des Lettres et de la Philosophic. 2 vols. 8vo. Paris, 1810. Memorie della Reale Accademia della Scienze di Torino. Serie Seconda. Tomo XIV. 4to. Torino, 1854. Mac vicar, J. G. — Elements of the Economy of Nature, or the Principles of Physics, Chemistry, and Physiology. 8vo. 1830. Tryon,T. — Lettei-s on Subjects Philosophical, Theological, andjMoral. 12mo. 1700. Howell, J. W.— The Unity of Nature. 8vo. 1849. Leeuwenhoek, A.— Arcana Naturae ope et beneficio Microscopiorum detecta. 4to. Lug. Bat. 1696. Addison, W. — The actual Process of Nutrition in the Living Structure, de- monstrated by the Microscope, &c- 8vo. 1843. Hales, Stephen,— Statical Essays : Vegetable Statics and Haemastatics. 3rd Ed. 2 vols. 8vo. 17.38-1740. Varley, Cornelius. — A Treatise on Optical Drawing Instruments. 8vo. 1845. Valle'e, L. L.— Theorie de l*(Eil, Premiere Partie. 8vo, 1844-6. Reynaud, A. A. L.— Elemens d'Algebre. 3" Ed. 2 vols. 8vo. Paris, 1810. Elemens des Sections Coniques. Par M. M**. 8vo. Paris, 1757. Institutions de Physique. 8vo. 1741. Nollet, J. A. — Legons de Physique Exp^rimentale. 4« Ed. 5 vols. 12mo. Paris, 1753-5. Gay-Lussac, J. L. — Cours de Physique. 8vo. Paris, 1827. Baily, F.— Astronomical Tables and Formulae. 8vo. 1827. Boyle, R. — New Experiments touching the Spring of the Air and its eflfects (made for the most part in a new Pneumatical Engine^. 4to. 1662. Berzelius, J. J. — Nouveau Systeme de Min^ralogie. 8vo. Paris, 1819. La Platine, Tor blanc ou le Huitieme Metal. 12mo. Paris, 1758. De Bom, Ignace. — Methode d'extraire les Metaux parfaits des Minerais par le Mercure. 4to. Vienne, 1788. Bouillon-Lagrange, E. J. B. — Essai sur les Eaux Min^rales Naturelles et Artificielles. 8vo. Paris, 1811. Wardrop, J. — On Diseases of the Heart. 8vo. 1851. Royle, J F.— On the Antiquity of Hindoo Medicine. 8vo. 1837. Berthier, M. P. — Memoires et Notices Chimiques, Mineralogiques, &c. 8vo. Paris, 1833. IjC Begue de Presle — Le Conservateur de la Sante. 12mo. Paris, 1763. Berzelius, J. J. — Essai sur la Theorie des Proportions Chimiques. 8vo. Paris, 1819. Chevreul, E. — Considerations gen^rales sur 1' Analyse Organique. 8vo. Paris, 1824. Elemens de Chimie Th6orique et Pratique, pour servir aux cours public de I'Acad^mie de Dijon. 3 vols. 12mo. 1777-8. . Collectanea Chymica — A collection of several Treatises in Chymistry con- cerning the Liquor Alkahest, the Mercury of the Philosophers, &c. Svo. 1684. Gay-Lussac, J. L. — Cours de Chimie. 2 vols. 8vo. Paris, 1828. De Nuisement, Le Sieur — Traittez du Vray Sel, secret des Philosophes et de I'Esprit Gene'ral du Monde. 12mo. Paris, 1621. Laugier, M.— Chimie G6n6rale. 3 vols. 8vo. 1828. Low, D.— Inquiry into the Nature of the Simple Bodies of Chemistry. 2nd Ed. 8vo. 1848. Louyet, P. — Cours El^mentaire de Chimie G6n6rale. 3 vols. 8vo. Brux- elles, 1841-4. Macquer, M. — Dictionnaire de Chymie ; avec une Supplenaenl, par M. H. Struve. 5 vols. 8vo. Neuchatel, 1789. 138 General Monthly Meeting. [June 4, laraday, Professor^ D.C.L. F.JR.S. — Pictet, M. A,— Essais sur le Feu. 8vo», Geneve, 1790. Pott, J. H.— Dissertations Chymiques, recueillies et traduites, par J. F. Demachy. 4 vols. 12mo. Paris, 1759. Recueil de Memoires et d' Observations sur la Formation et sur la Fabrication du sal petre. Par les Commissaires norames par TAcademie pour le juge- meut du prix du sal petre. 8vo. Paris, 1776. Segur, Octave. — Lettres Elementaires sur la Chimie. 2 vols. 18mo. 1803. Stahl, G. E.— Traite' des Sels. 18mo.* Paris, 1783. Otto Tachenius. — Hippocrates Chymicus. Translated by J. W. 4to. 1677. Briick, R. — Electricite ou Magnetisme du Globe Terrestre. 8vo. Bruxelles, 1851. Bostock, J. — An Account of the History and Present State of Galvanism. 8vo. 1818. Carpue, J. C. — An Introduction to Electricity and Galvanism. 8vo. 1803. Nollet, J. A.— Lettres sur I'Electricit^. Nouvelle Ed. 2 vols. 12mo. Paris, 1764. Guglielmini, D. — Delia Natura de Fiumi. 4to. Bologna, 1697. Smyth, Capt. W. H. — Nautical Observations on the Port and Maritime Vicinity of Cardilf, and on the Bute Docks. 8vo. 1840. Theophrastus. — History of Stones, by J. Hill : with two Letters. 8vo. 1746. Martin, W. — Outlines of an attempt to establish a knowledge of Extraneous Fossils. 8vo. 1809. Burnet, T.— The Theory of the Earth. 3rd Ed. fol. 1697. Smith, J. Pye — On the Relation between the Holy Scriptures and some Parts of Geological Science. 8vo. 1839. Schlagiutweit, H. und A. — Untersuchungen iiber die Physikalische Geogra- phic der Alpen. 4to. 1850. Knight, W. — Facts and Observations towards forming a New Theory of the Earth. 8vo. 1818. Eaton, A. — Geological Text-book (for America.) 8vo. Albany, U.S. 1830. Ainsworth, W. — Account of the Caves of Ballybunian in the county of Kerry. 8vo. Dublin, 1834. Exposition des Produits de 1' Industrie Frangaise en 1839— Rapport du Jury central. 3 vols. 8vo. Paris, 1839. Treatise on Calico Printing. 12mo. 1793. Black, W. — A Practical Treatise on Brewing. 8vo. 1835. Moseley, B. — A Treatise on Sugar. 8vo. 1799. Curr, J. — Railway Locomotion and Steam Navigation ; their Principles and Practice. 8vo. 1847. Hall, Mr. — The principal Roots of the Latin Language. 8vo. 1825. Roberts, T. — An English and Welsh Vocabulary. 12mo. 1827. Forde, W. — The True Spirit of Milton's Versification developed. 8vo. 1831. Schweigger, J. S. C. — Einleitung in die Mythologie. 8vo. Halle, 1836. Fellows, Sir Charles, V.P.R.I. {tlte Author) — Coins of Ancient Lycia before the reign of Alexander : with an Essay on the relative dates of the Lycian- Monuments in the British Museum. 8vo. 1855. Franklin Institute of Pennsylvania — Journal, Vol. XXIX. Nos. 4, 5. 8vo. 1855. Geological Society — Quarterly Journal, No. 42. 8vo. 1855. Graham, George, Esq. Registrar- General — Reports of the Registrar-General for May, 1855. 8vo. Hamilton,W. J. Esq. Pres. Geol. Soc. (^the Author)— Address a,t the Anniversary Meeting of the Geological Society, Feb. 16, 1855. 8vo. 1855. Hopkins, Thomas M. Esq. {the Author) — On the Atmospheric Changes which produce Rain and Wind. 2nd Ed. 8vo. 1854. Horticultural Society of London — Journal, Vol. IX. Part 4. 8vo. 1855. Ingall, G. H. Esq.— The History of Britain. By John Milton. 4to. 1670. 1855.] Prof Faraday on Ruhmkorff*s Apparatus. 139 Jennings^ Eichard, Esq. M.A. M.R.I, {the Author)— 'N&tur&l Elements of Political Economy. 16mo. 1855. London, Libran/ Committee of the Corporation — Catalogue of London Traders' Tokens— Beaufoy Cabinet. By J. H. Burn. 2nd Ed. 8vo. 1855. Manning, Frederick, Esq. M.R.I. — The Life of Thomas Ken, Bishop of Bath and Wells. By a ikyman. 2nd Ed. 2 vols. 8vo. 1854. Approach to the Holy Altar. By Bishop Ken. l(5mo. 1854. Exjxksition of the Apostles' Creed. Bp. Bishop Ken. 16mo. 1854. Noveilo, Mr. {the Publisher) — The Musical Times for May, 1855. 4to. Phillivps, Sir TJiomas, Bart. F.R.S. F.S.A. M.R.I, {the Author)— Index Nominum in Libris Dictis Cole's Escheats. ICrao. 1852. Photoqraphic Society — Journal, No. 30. 8vo. 1855. Radclijfe lYustees, Oa/ord— Astronomical and Meteorological Observations made at the Radcliffe Observatory, in 185.3. 8vo. 1855. Royal Socicfy.— Proceedings, Vol. VII. No. 12. 8vo. 1855. Sachische Gesellschnft, Leipzig. — Abhandlungen, Band III. Heft 7. 8vo. 1854. Berichte, Phil. -Hist. Classe. 1854. Heft 2-6 ; 185.5. Heft 1,2. 8vo. Gedachtnissrede auf Friedrich August, Kiinig von Sachsen. Von E. von Wietersheim. 8vo. 1854. Scharf, George, Esq.jun. F.S.A. (the Author) — Notes upon the Sculptures of a Temple discovered at Bath, in 1790. 4to. 1855. Society of Arts — Journal for May, 1855. 8vo. Statistical Society -J oum&l. Vol. XVlll. Part 2. 8vo. 1855. Wrey,J. W. Esq. M.A. il/.i?./.— Explanations: a Sequel to "Vestiges of the Natural History of Creation." By the Author of that work. 12mo. 1846. WEEKLY EVENING MEETING, Friday, June 8. The Duke op Northumberland, K.G. F.R.S. President, in the Chair. Professor Faraday, D.C.L. F.R.S. On Ruhmkorff's Induction Apparatus. This apparatus is known to consist of a soft iron core, intended to act magnetically, around which there is a coil of coarse copper wire, to be connected at pleasure with few or many cells of a voltaic battery ; and external to this is a second coil of much thinner copper wire, having great length, in which the peculiar currents of the apparatus are to be produced. The coils of the wires are insulated from one another by a very careful mode of preparation. The inner, called the primary coil, is supplied with an automatic con- trivance, so that when the battery is connected with it, the con- tinuity is broken, to be renewed again an instant after ; and thus a 140 Professor Faraday [June 8, series of short intermitting currents, rapidly recurring, pass through it instead of one constant current. The outer coil, usually called the secondary, has its terminations apart ; and these can be con- nected either metallically by a wire, or arranged with any interval or apparatus placed between them, in which effects of the induced current are to be shown, and by which its characters are to be examined. When the secondary circuit is metallically complete, each brief current in the primary wire causes, according to well-known prin- ciples {Exp. Res. 10, &c.), two successive currents in opposite directions in the secondary wire ; and if a galvanometer be included in the secondary circuit, it is seen that the communica- tion of the primary wire with the battery is followed by a deflection of the needle in one direction, which then gradually swings to and fro, accompanied by curious spasmodic motions (which are under- stood upon a moment's inspection), until it comes to zero : if the primary current be then stopped, the galvanometer needle is de- flected in the other direction, and after a few oscillations subsides quietly to zero again. The sum of the alternate induction cur- rents having been thus shown to be equal in effect to zero, it was then explained how, if the secondary currents be interrupted in the smallest degree, even by the intervention of a hair or a piece of paper, all the currents of one kind, due to the beginnings of the short inducing currents in the primary wire, were stopped off from the secondary wire (being expended in the primary wire itself;, and only those due to the cessations of the primary currents left to show their power there ; so that the secondary wire could then give a continuous series of intermitting (but not alternating) currents, all of which, therefore, had a common direction. The remarkable character of the electricity of these currents was then shown and explained. Its intensity is such that it can strike across J or ^ an inch of air, whilst the intensity of the inducing current is so feeble that it cannot traverse any sensible striking distance : but it was also shown, that the more intense the electricity the less the sum of force transmitted in a given time by the action of the same battery and apparatus ; and that when the interruption of the secondary circuit was the smallest possible, as by a hair's-breadth, the largest amount of electricity passed through the galvanometer connected with it. The power of the induced current to pass through six inches or more of rarified air, was shown in the form of Gassiot's cascade :* and the conversion of the dynamic force of the primary and inducing current into the static force of the induced electricity, was illustrated by the charging of electrometers and Leyden jars. When the secondary current is interrupted, as just described, the inducing power of the primary current acts in its own wire to pro- * Phil. Mag. 1854, vii. p. 99. 1855.] on Ruhmkorff*s Induction Apparatus. 141 duce certain hurtful or wasteful results. Fizeau, by applying a Leyden jar (or its equivalent,) to the parts of the primary circuit near the contact breaker, took up this extra power at the moment of time, and converted it to a useful final purpose, upon principles belonging to static induction, the effects of which were briefly ex- plained. Masson,* Grove,f and Sinsteden have made a like applica- tion to the terminals of the secondary wire ; and Grove has pointed out striking changes in the character of the currents in it thus produced, and useful applications of the results. For instance, the spark in air between the ends of two platinum wires con- nected with the secondary terminals is flame-like, soft, and comparatively quiet compared with that which is produced when the terminals are respectively connected with the inner and outer coatings of a Leyden jar ; for then it becomes very bright, sonor- ous, and apparently large, so that two sparks can hardly differ more than the same spark under these circumstances. The differ- ences are even greater than the appearances show ; for whilst the powerful rattling spark cannot fire wood, or paper, or even gun- powder, except by the use of expedients, the soft quiet spark at once inflames any of them. The effect of the static induction thus introduced is not so much to vary the quantity of electricity which passes, as the time of the passage. That electricity which, moving with comparative slowness through the great length of the secondary coil, produces a spark having sensible duration (and therefore in character like that of a Leyden jar passed through a wet thread,) is, when the jar is used, first employed in raising up a static induc- tion charge, which when discharged produces a concentrated spark of no sensible duration, and therefore much more luminous and audible than the former. Fixing a piece of platinum wire horizon- tally across the ball of a Leyden jar, and then bringing the platinum wire secondary terminals respectively near its ends, two interruptions are. produced in the secondary circuit, the sparks at which are like each other and equal in quantity of electricity, for the jar as yet forms only an insulating support. But if, in addition, either secondary terminal be connected by a wire with the outside of the jar, the spark on that side assumes the bright loud character before described, but ceases to fire gunpowder or wood ; and no one would at first suppose, what is the truth, that there is the same electricity passing in one as in the other. Another interesting effect of the static induction is the double spark. If one of the secondary terminals be connected with the outside of a Leyden jar, and the other be continued until near the knob or a wire connected with it, a soft spark appears at that inter- val for every successive current in the primary circuit. This spark, however, is double ; for the electricity thrown into the jar at the * Prize Essay, Haarlem Trans. 1854, pp. 46, 47. t Phil. Mag. Jan. 18.55, ix. p. 1. 142 Prof. Faraday on Rulunkorff^s Apparatus. [June 8, 1855. moment of induction, is discharged back again at the same place the instant the induction is over ; the first discharge heats and prepares the air there for the second discharge, and the two are so nearly simultaneous as to produce the appearance of a single spark to the unaided eye. Reference was then made to the hopes raised by this instrument, of advance in the investigation of the magneto-electric power, by means of the great aid which it seems competent to supply. The results obtained by Grove* apparently referable to polarization were adverted to ; as also the remarkable transverse bands presented in the recurring discharge across very rarified airf ; and, founded as the instrument is by its core and its wires upon the joint effects of electro-dynamic and magneto-electric induction, it was observed that it gave great promise of aid in the investigation of that condi- tion of either the space or the ether which is about magnets, and around every discharge of electricity, whether in good or bad conductors, and which is expressed by the terms (themselves syn- onymous) of the magnetic or the electrotonic state. [M. F.] * Phil. Trans. 1852, p. 93, &c. f Phil. Mag. 1852, iv, p. 514. ISoual Institution of (Kreat ISritain. 1855. WEEKLY EVENING MEETING, Friday, June 15. H.R.H, The Prince Albert, KG, F.R.S. Vice-Patron R.L, in the Chair. Colonel H. C. Rawlinson, On the Restdts of the Excavations in Assyria and Babylonia. These excavations, independently of the treasures of art disclosed by them, have opened up to us a period of about 2000 years in the world's history, which, as far as the East is concerned, was before almost entirely unknown. The cuneiform inscriptions of Babylonia and Assyria furnish a series of historical documents from the 22nd century B.C. to the age of Antiochus the Great. The speaker divided these documents into three distinct periods of history, the Chaldaean, the Assyrian, and the Babylonian, and he then proceeded briefly to describe each period in succession. During the Chaldaean period the seat of empire was to the south, towards the confluence of the Tigris and Euphrates, and the sites of the ancient capitals were marked by the ruins of Mugheir, of Warka, of Senkereh, and of Nifler. At Mughier, called in the inscriptions Jlur, and representing the biblical Ur of the Chaldees, inscriptions have been found of a king, ^^Kudur, the conqueror of Syria," who was probably the Chedorlaomer of the Bible. At any rate, a king named Jsmi-Da^an, who lived some generations later, is proved, by a series of chronological dates found in the Assyrian tablets, to belong to the 19th century B.C., so that the era of the earlier king agrees pretty well with the ordinary computation of the age of Abraham. The names of about twenty-five kings have been recovered of the ancient period, and there are good grounds for believing that the Assyrians did not succeed in establishing an independent empire at Nineveh till the early part of the fifteenth century B.C. From B.C. 1273 to 625, the Assyrians seem to have been the lords paramount of Westeni Asia, and their history is preserved Vol, II.— (No. 22.) l 144 Col. Rawlinson, on the Results of the [June 15, in an almost continuous series of documents, from the institution of the empire to the taking of Nineveh by the Medes and Babylonians. During the later part of this period, or from about 800 B.C., Jewish history runs in a parallel line with that of Assyria ; and wherever a comparison can be instituted between the sacred records and the contemporary annals of Nineveh, the most complete agreement is discovered between them ; and that not only in regard to the names of the kings, but also in respect to their order of succession, their relationship to each other, the wars in which they were engaged, and even the leading features of those wars. Col. Rawlinson noticed many such examples of coincidence, and drew attention to the great value of the verification which was thus obtained of Scripture history. The third, or Babylonian period, was then shortly discussed ; the reigns of Nebuchadnezzar and Nabonidus being especially se- lected for illustration. A description was given of the excavation of the great ruin near Babylon called Birs Nimrud, and a translation was read of the edict of Nebuchadnezzar inscribed upon the clay cylinders, which were found imbedded in the walls of the temple. A number of original relics, discovered among the ruins of Chal- daea, Assyria, and Babylonia, and illustrative of these three periods of history, were also exhibited to the meeting, previously to their being deposited in the British Museum. LIST OF KINGS. I. Chald^ean Period. Name of King. ^^St""^' Urukh .... B.C. 2234 Ilgi. . . . Sinti-Shil-Khak Kudur-Mapula Ismi-Dagan Ibil-Anu-Duma Gurguna . Naram-Sin Durri-Galazu . Purna-Puriyas . Khammurabi . Samshu-Iluna . Sin-Shada . 1950 1*860 1700 1600 Name of King. Rim-Sin Zur-Sin . . Merodach-Gina Approximate Date. B.C. 1500 II. — Assyrian Period 1400 1300 Belukh . . . . . 1273 Pudil . . . . . \2^5 Phulukhl. . . . . 1240 Shalama-Bar I. . . 1220 Sanda-Pal-Imat . 1200 Asshur-Dapal-Il . 1185 Mutaggil-Nebo . . . 1165 Asshur-Rish-Ipan . 1140 1855.] Excavations in Assyria and Babylonia. 145 Name (^ King. Approximate Date. Tiglath-Pileser I. . b.c. 1120 Asshur-Bani-Pal I. . . 1100 Asshur-Adan-Akhi . . 950 Asshur-Danin-Il . . 925 Phulukhll. ... 900 Tigulti-Sanda . . . 880 Sardanapalus . . . 850 Shalama-Bar IL . . 815 (Asshur-Danin-Pal) Shamas-Phul ... 780 Phulukh III. for Pul and 1 ^^ Samuramit (Semiramisj Tiglath-Pileser II. . . 747 Shalmaneser (?) . . 730 Name (f King. Sargon Sennacherib Esar-haddon Asshur-Bani-Pal II Asshur-Emit-Ilut B.C. Approximate Date. 721 702 680 660 640 to 625 III. — Babylonian Period. 625 605 Nabopolassar Nabokodrossor (or 1 Nebuchadnezzar) j Evil-Merodach ... 562 Nergal-Shar-Ezer . . 560 Nabonidus, and Bel-Shar-) 554 Ezer (Belshazzar) . jto53S Taking of Babylon, by Cyrus. N.B. — It must be understood that the reading of many of these names is still far from certain. [H. R.] GENERAL MONTHLY MEETING, Monday, July 2. SiE Chables Fellows, Vice-President, in the Chair. Thomas Pargiter Dickenson, Esq. Thomas Dunn, Esq. John MacLennan, M.D. and Captain Raymond White, were duly elected Members of the Royal Institution. Eustace Anderson, Esq. J. Richard Andrews, Esq. John Sherard Coleman, Esq. William Delannoy, Esq. and Col. William Loyd, were admitted Members of the Royal Institution. l2 146 General Monthly Meeting, [July 2, The following Presents were announced, and the thanks of the Members returned for the same : — From Airy^ G, B. Esq. F.R.S. Astronomer-Royal— 'Re^ri on Greenwich Obser- vatory. June 2, 1855. 4to. ^s/ronomtcaZ Sbctef.y, /^o_yaZ— Monthly Notices. Vol. XV. No. 7. 8vo. 1855. Bell^ Jacob, Esq. M.E.I. — Pharmaceutical Journal for June, 1855. 8vo. Bertie, Hon. and Rev. Frederick. — Five Generations of a Loyal House — ■ Part I.— Lives of Richard Bertie, and his son Peregrine Lord Willoughby. By Lady Georgina Bertie. 4to. 1845. Boosev, Messrs. {the Publishers) — The Musical World for June, 1855. 4to. Bradbury, Henry, Esq. M.R.I. — The Ferns of Great Britain and Ireland. By T. Moore, F.L.S. Edited by J. Lindley, Ph.D. F.L.S. Parts, fol. 1855. British Architects, Royal Institute o/— Proceedings in June, 1855. 4to. Coleman, J. Sherard, Esq. M.R.I. — Journal of the Ethnological Society of London. Vols.I-Ill. 8vo. 1848-54. Commissioners in Lunacy. — Ninth Report. 8vo. 1855. Diamond, Hugh W. M.D. M.jR./.— Fac-simile of a Letter from Sir H.Davy to Sir F. Baring, dated October 3, 1805 (relating to the London Institution Museum). East India Company, Hon. — Fibrous Plants of India, fitted for Cordage and Paper. By J. Forbes Royle, M.D. F.R.S. 8vo. 1855. jEytVori" —The Medical Circular for June, 1855. 8vo. The Practical Mechanic's Journal for June, 1855. 4to. The Journal of Gas- Lighting for June, 1855. 4to. The Mechanics' Magazine for June, 1855. 8vo. Deutsches Athenaum for June, 1855. 4to. The Athenaeum for June, 1855. 4to. Faraday, Professor, D.C.L. i^.i?.dalite, Tautalite, Sapphirin, and AUanite, from Greenland. Tanlor^ Rev. VK.— Taylor's Reflecting Tube. WEEKLY EVENING MEETING, Friday, April 11. Sir Charles Fellows, Vice-President, in the Chair. C. AV. Siemens, Esq. C.E. On a Regenerative Steam-Engine. The application of the steam-engine to our various purposes of manufacture and locomotion is of very recent date, although the elastic force of steam was known even by the ancients ; for we read in Hero of Alexandria, on Pneumatics (translation by Woodcroft), that the Egyptian priesthood made use of it for their somewhat undignified purpose of performing pretended miracles before an ignorant population. The first suggestion of its useful application for^raising water is due to the Marquis of Worcester, and dwelt upon in his " Century of Inventions." The idea was taken up by Papin, Savory, and Newcomen, who added important elements towards its practical realization ; but to James Watt belongs the merit of having laid down a comprehensive principle of the steam-engine, and of having devised means to render the same capable of performing the rudest as well as the most delicate operations. • If any proof were wanting of the great genius of Watt, it would be sufficient to observe that the steam-engine of the present day is, in point of principle, still the same as it left his hands half a cen- tury ago, and that our age of material progress could only affect its form. Great honour, however, is due to Fulton, Stephenson, Nasmyth, and others, for having adapted the same to the most important purposes. 228 Mr, C, W. Siemens, an a [April 11, The steam-engine of Watt was composed of four organic parts, which were pointed out on a working model before the meeting, namely : — 1. The furnace, or chamber of combustion, with its flues and chimney. 2. The boiler, or steam generator. 3. The steam- vessel, or cylinder, wherein the elastic force of the steam is imparted to the piston, or other first moving parts of the machinery. 4. The condenser, where the elastic force of the steam is destroyed by abstracting its latent heat, 'by injection of cold water, or by ex- posure of cooled metallic surfaces.. In the case of high-pressure engines, it would seem that the condenser was suppressed ; but it might be said, that this class of engines makes use of one great common condenser, namely the atmosphere; the separate con- denser possessing only the advantage of relieving the working piston of the opposing atmospheric pressure. The only essential improvement of the steam-engine that has been introduced since the time of Watt consists in working the steam expansively, whereby a considerable economy has been attained ; but it is well known that Watt foresaw the advantages that would be realised in this direction, and was prevented only by insufficiency of the mechanical means at his disposal from realising the same. The lofty superstructure proved the soundness of the foundation Watt had laid ; and it would seem hopeless to change the same, unless it could be proved that the very principle regarding the nature of heat, whereon Watt had built, had given way to another more comprehensive principle. The engine of Watt was based upon the material theory of heat that prevailed at his time, and almost to the present day. According to this theory, steam was regarded as a chemical compound of water and the supposed im- ponderable fluid " heat," which possessed amongst others the pro- perty of occupying under atmospheric pressure nearly 1 700 times the bulk of the water contained in it. The Boulton and Watt con- densing engine took the full advantage of this augmentatioh of volume, which effected a proportionate displacement of piston, and the condensation of the steam obviated all resisting pressure toithe piston. In the course of the last few years our views of the nature of heat had however undergone a complete change ; and, according to the new " dynamic theory," heat, as well as electricity, light, sound, and chemical action, are regarded as different manifestations of motion between the intimate particles of matter, and can be ex- pressed in equivalent values of palpable motion and dynamic effect. In support of this theory, he (Mr. Siemens) could not do better than refer to the able discourses, recently delivered in the lioyal Institution, by Mr. Grove and Professor Thomson.* Viewed from the position of the new theory, the heat given ou^ in the condenser of a steam-engine, represented a loss of mechanical * See pp. 152 and 199. 1856.] Regenerative Steam-Engir^. 229 effect, amounting to ri part of the total heat imparted to the boiler ; and the remaining y'j part was all the heat really converted into mechanical effect. The greater proportion of the lost heat might be utilized by a perfect dynamic engine. A vast field for practical discovery was thus opened out ; but it might yet be asked whether it was worth while to leave our present tried and approved forms of engines, to seek for economy, however great, in a new direction, considering the vast extent of our coal fields. The reply to this objection was, that the coal in its transit from the pit to the furnace acquired a considerable value, which, for this country, might be estimated at £8 per horse-power per annum (taking a consumption of 13^ tons of coal, at an average expen- diture of 12 shillings per ton). Estimating the total force of the stationary and locomotive engines employed in this country at one million nominal horse- power ; it followed that the total expenditure for steam coal amounted to eight millions pounds sterling per annum, of which at least two-thirds might be saved. In other countries, where coal is scarce, the importance of economy becomes still more apparent ; but it is of the highest importance for marine engines, the coals whereof had to be purchased at transatlantic stations, at a cost of several pounds per ton, to which must still be added the indirect cost of its carriage by the steamer itself in place of merchan- dise. These observations, Mr. Siemens thought, might justify him in bringing before the Institution an engine, the result of nearly ten years' experimental researclies, which he thought to be the first practical application of the dynamic theory of heat, of which he was proud to call himself an early disciple. . Others, more able than himself, might probably have arrived sooner at a practically useful result ; but he might claim for himself at least that strong conviction, approaching enthusiasm, which alone could have given him strength to combat successfully the general discouragement and the serious disappointments he had met with. The following illustrations, proving the imperishable nature of physical forces and their mutual convertibility, were made use of to indicate more clearly the principles his engine was based upon. A weight falling over a pulley, to which it was attached by a string, would impart rotary motion to a fly wheel, fixed upon the same axis with the pulley, and the velocity imparted to the wheel would cause the string to wind itself upon the pulley, till the weight had reached nearly its original elevation. If the friction of the spindle and the resistance ofthe atmosphere could be dispensed with, the weight would be lifted to precisely the same point from whence it fell, before the motion ofthe wheel was arrested. In descending again, it would impart motion to the wheel as before, and this opera- tion of the weight, of alternately falling and rising, could continue ad infinitum. If the string were cut at the instant when the weight 230 Mr. C. W. Siemens, on a [April U, had descended, the rotation of the wheel would continue uniformly, but it might soon be brought to a stop by immersing it in a basin filled with water. In this case the water was the recipient of the force due to the falling weight residing in the wheel ; and by repeating the same experiment a sufficient number of times, we should find an increase of temperature in the water, a fact discovered by Joule, in 1843, which first proved the identity of heat and dynamic effect, and established their numerical relation. If the weight falling over a pulley were one pound, and the distance through which it fell one foot, then each impulse given to the wheel would represent one foot pound, or commonly adopted unit of force ; and if the water contained in the basin weighed also one pound, it would require 770 repetitions of the experiment of arrest- ing the wheel in the water, before the temperature of that water was increased by one degree Fahrenheit. Another illustration made use of, was that of a hammer falling in vacuo upon a perfectly elastic anvil. The hammer would, under these circumstances, rebound to precisely its original elevation ; and granting the perfect elasticity of both hammer and anvil, neither sound nor heat would be produced at the point of concussion. If a piece of copper v/ere suddenly introduced between anvil and hammer, the latter would not rebound, but would make the copper the recipient of the expended force. If the hammer were now lifted again and again by an engine, and the piece of copper were turned about on the anvil, so that at the end of the operation it had pre- cisely the same form as at the commencement, then no outward effect would be produced by the force expended, but the piece of copper would be heated perhaps to redness ; and if the engine employed to lift the hammer were perfect, then the heat produced within the copi>er should be sufficient to sustain its motion. A familiar instrument for converting force into heat was the fire-syringe. The force expended in compressing the air imparted a sufficient temperature to the same to ignite a piece of Gerraaa tinder (about 600^ Fah.). When the plunger of the syringe was drawn back, it might be observed that the temperature of the enclosed air was again reduced to its original degree, because the heat developed in compression of the air had been spent again in its expansion behind the piston. If the expansion of the heated and compressed air had been without resistance, no reduction of its temperature could have taken place, because no force would be obtained ; a fact which had been recently proved by Kegnault, and which was perhaps the strongest proof in favour of the dynamic theory of heat that could be brought forward. If the heated and com- pressed air in the fire-syringe could be produced by some external cause and be introduced behind the plunger after it had descended freely to the bottom, then the force imparted to the plunger in the expansion might be turned to some useful purpose, and a dynamically perfect engine might be obtained. But although the elevated tem- 1856.] Regenerative Steam- Engine, 231 perature might be readily supplied by means of a fire, it would not be possible to give a sufficient density to the air, except by an expen- diture of force in its compression. If, however, heat were applied to a drop of water confined below the plunger till its temperature was raised sufficiently to effect its conversion into steam of the density of the water itself, (Gaignard de la Tour's state of vapours,) and then allowed to expand below the plunger till its temperature was reduced to zero, a dynamically perfect engine would be obtained. The impracticable nature of such an engine was however manifest, if it was considered that steam of the density of the water producing it, would exert a pressure of probably several hundred atmospheres, which pressure the moving part of the engine must be mnde strong enough to bear at a temperature of more than 1000'' Fah., and that the capacity of the working cylinder must be sufficient to allow of an expansion of the steam to several thousand times its original volume. It was therefore necessary to look for other means of ob- taining from heat its equivalent value of force, which means, it was contended, were furnished by the " regenerative steam-engine." This engine, of which several diagrams and a model were ex- hibited, consisted of three essential parts, namely, the furnace ; the working cylinder, with its respirator and heating vessel ; and the regenerative cylinder. It consisted also of a boiler and condenser, (unless the steam were discharged into the atmosphere,) but these were not essential to the working of the engine, although of great practical utility. The regenerative cylinder had for its object alternately to charge and discharge two working cylinders, and the action of its piston might be compared to that of a hammer oscil- lating between two elastic anvils. The regenerative cylinder com- municated at its one extremity with one working cylinder, and at the other extremity with another and similar working cylinder, and these communications were not intercepted by valves. The working cylinders were so constituted that their capacity for steam of con- stant pressure was the same, no matter where the working piston stood. Each consisted of a cylinder of cast iron, open at both ends, which was completely enclosed in another cylinder or heating vessel, one end of which was exposed to the action of a fire. Within the inner cylinder was a large hollow piston, filled with non-conducting material, to which was attached a long trunk or enlarged hollow piston rod of nearly half the sectional area of the piston itself. This trunk was attached to the working crank of the engine in the usual manner. The trunk of the second working cylinder stood precisely opposite, and was connected with the same crank. The piston of the regenerative cylinder was also connected with the same crank, but stood at right angles to the two working, cylinders. The con- sequence of this arrangement was, that while the two working trunks made their strokes (the one inward and the other outward) the piston of the regenerative cylinder remained comparatively quiescent upon its turning or dead point, and vice versa. Around the two 232 Mr. C. W. Siemens, on a- [April 11, heating vessels boilers were disposed, which received the heat of the fire, after it had acted upon the former. The steam generated within the boilers was introduced into the engine by means of an ordinary slide valve (of comparatively very small dimensions) at short intervals, and when the piston of the regenerative cylinder was in its extreme position. The admission of the steam, which was of high pressure, took place on that side of the regenerative cylinder where compression by the motion of its piston had already taken place, and at the same instant a corresponding escape of expanded steam on the other side of the regenerative piston was allowed to take place into the atmosphere. The quantity of steam freshly admitted at each stroke did, however, not exceed one- tenth part of the steam contained in the working cylinders of the engine, and served to renew the same by degrees, while it added its own expansive force to the effect of the engine. The compression of the steam into either of the working cylinders took place when its hollow piston stood at the bottom. While in this position the steam occupied the annular chamber between the working trunk and the cylinder, besides the narrow space between the cylinder and the surrounding heating vessel. The pressure of the steam being the same above and below the hollow piston, but the effective area below being equal to twice the area above, the working trunk, attached to the piston, would be forced outward through the stuffing box, while the steam of the annular chamber above the piston passed through the narrow space intervening, into a space of twice the capacity of the annular chamber below the hollow piston. During its passage the steam had to traverse a mass of metallic wire gauze or plates, (the respirator, presenting a large aggregate surface,) which reached at one end sufficiently downward into the heating vessel so that its temperature was raised from 600 to 700° Fah., while its other extremity remained at the temperature of saturated steam, or about 250° Fah. In consequence of the addition of temperature the steam received on its passage through the respirator, its elastic force was doubled, and it therefore filled the larger capacity below the hollow piston or displacer without loss of pressure. When the effective stroke of the working trunk was nearly completed, the regenerative piston commenced to recede, and the steam below the hollow piston expanded into the regenerative cylinder, depositing on its regress through the respirator the heat it had received on its egress through the same, less only the quantity that had been lost in its expansion below the working piston, and which was converted into dynamic effect or engine power, and which had to be supplied by the fire. The expansion and simultaneous reduction of tempe- rature of the steam caused a diminution of its pressure from four to nearly one atmosphere ; and the working trunk could now effect its return stroke without opposing pressure, and while the second working trunk made its effective or outward stroke impelled by a pressure of four atmospheres. 1856.] degenerative Steam- Engine. 233 The respirator, which was invented by the Rev. Mr. Stirling, of Dundee, in 1816, fulfilled its office with surprising rapidity and perfection, if it were made of suitable proportions. Its action was proved at the end of the discourse by a working model. It had been applied without success to hot-air engines by Stirling and Ericsson, but failed for want of proper application ; for it had been assumed (in accordance with the material theory of heat) that it was capable of recovering all heat imparted to the air, and, in consequence, no sufficient provision of heating apparatus had been made. It having been found impossible to produce, what in effect would have been a perpetual motion, the respirator had been discarded entirely, and was even now looked upon with great suspicion by engineers and men of science. Mr. Siemens had, however, no doubt that its real merits to recover heat that could not practically be converted by one single operation into mechanical effect, would be better appre- ciated. The rapidity with which the temperature of a volume of steam was raised from 250" to 650° Fah. by means of a respirator, was indicated by the fact that he had obtained with his engines a velocity of 150 revolutions per minute. The single action of heating the steam occupied only a quarter the time of the entire revolution of the engine, and it followed that it was accomplished in one-tenth part of a second. But, in explanation of this phenomenon, it was contended, that the transmitting of a given amount of heat from a hotter to a cooler body, was proportionate to the heating surface multiplied by the time occupied, and that the latter factor might be reduced ad libitum, by increasing the former proportionately. The air-engines of Stirling and Ericsson had failed also, because their heated cylinders had been rapidly destroyed by the fire ; but the cause for this was, that an insufficient extent of heating surface had been provided, and it was well known that even a steam- boiler would be rapidly destroyed under such circumstances. Mr. Siemens was led by his own experience to believe that his heating vessels would last certainly from three to five years ; and being only a piece of rough casting, that could be replaced in a few hours, and at a cost below that of a slight boiler repair, he considered that he had practically solved the difficulty arising from high temperature. It was however important to add, that all the working parts of his engine were at the temperature of saturated steam, and therefore in the same condition of ordinary steam-engines ; whereas in Erics- son's engine, the hot air had entered the working cylinder. In surrounding the heating vessel with the boiler, an excessive accu- mulation of heat was prevented from taking place, and the pressure of the steam in the boiler became the true index to the engine-driver of the temperature of the heating vessel. Another essential pro- perty of the heating vessel was, that all its parts should be free to expand by heat without straining other parts, which was accom- plished by a free suspension, and by undulating its surface. Lastly, it should be massive, to withstand the fire with impunity, for iron ^4 Mr. C. W. Siemens^ on a [April 11, was, strictly speaking, a combustible material. The pyropherus or finely divided metallic iron, took fire spontaneously on exposure to the atmosphere, a chip of iron was ignited in flying through the flame of a candle ; an iron tea-kettle was destroyed by exposing it (unfilled with water) to a kitchen fire ; whereas, in forging a crank shaft, the solid mass of iron withstands the white heat of the forge fire for several weeks without deteriorating. A heating vessel, properly constructed and protected, might be heated with safety to 700^ Fah., at which temperature it would be almost as able to resist pressure, as at the ordinary temperature of the atmosphere, the point of maximum strength of iron being at SoO'^ Fah., as had been proved by experiments made for the Franklin Institute. The construction of a heating vessel combining these desiderata was of paramount importance for the success of Mr. Siemens' engine, and had not been accomplished without combating against consider- able practical difficulty. Although heat may be entirely converted into mechanical effect, it would nevertheless be impossible to construct an engine capable of fulfilling this condition without causing at the same time a portion of heat to be transferred from a hotter to a cooler body, and which must ultimately be discharged. This necessity has been generally proved, and in a very elegant manner, by Professor Clausius, of Ziirich, and implies at least the partial truth of '' Car- net's theory." In the " regenerative steam-engine," provision had been made for absorbing this quantity of heat, arising in this case from the circumstance, that the saturated steam enters the respirator in a state of greatest density or compression, and returns through it (expanding into the regenerative cylinder) at a gradually diminishing density, although the temperature of the extreme edges of the respi- rator remains proportionateHo the condensing point of the steam of greatest density, by providing water chambers about the cover of the working cylinder, and around the regenerative cylinder, which are in communication with the steam-boiler. The heat absorbed from the slightly superheated steam is thus rendered useful to generate fresh steam. Objection had been raised by casual observers against the rege- nerative steam-engine, on account of its apparent similarity in prin- ciple to the " air-engines " of Stirling and Ericsson, implying similar sources of failure. The apparent similarity in principle arose from the circumstance that both Stirling and Ericsson, as well as himself, had employed the respirator and high temperatures ; but these were but subordinate means or appliances, that might be resorted to in carrying out a correct as well as an erroneous principle. In the winter of 1852-53, when Ericsson was engaged lipon his gigantic experiment in America, the speaker had had occasion to read a paper to the Institution of Civil Engineers, entitled, " On the conversion of heat into mechanical effect," wherein he had endeavoured to set forth the causes of the probable failure of that 1856.] Regenerative Steam-Engine. 235 experiment, and to guard against a sweeping condemnation on that account of some of the means Ericsson had employed. According to the dynamic theory of heat, the elastic medium employed in a perfect caloric engine was a matter of indifference, and air had been resorted to, because it was perfectly elastic, and always at hand. In practice, however, the elastic medium em- ployed was a matter of very great importance, and he (Mr. Siemens) had given the decided preference to steam, and for the following reasons : — 1. The co-efficient of expansion of saturated steam by heat exceeded that of air in the proportion of about 3 : 2, but decreased with an increase of temperature. This was not in accordance with the established rule by Gay-Lussac and Dal ton, but was the result of his own experiments (described in a paper, '• On the expansion of steam, and the total heat of steam," communicated to the Insti- tution of Mechanical Engineers, in 1850), and had been borne out by his practical experience on a large scale. Mr. Siemens had been first induced to undertake these experiments in consequence of an observation by Faraday, that the elastic force of the more permanent vapours gave way rapidly, when by abstraction of heat their points of condensation was nearly obtained. He conceived that gases and vapours would expand equally by heat, when com- pared, not indeed at the same temperature, but at temperatures equally removed from their points of condensation. 2. When saturated steam was compressed (within the regene- rative cylinder), its temperature would not rise considerably (as the fire-syringe evinced in respect of air), because Regnault had proved that the total heat of steam increased with its density, and conse- quently the heat generated in compression was required by the denser steam to prevent its actual condensation. Without this fortunate circumstance, the steam would be heated already by com- pression to such an extent, that it would be difficult indeed to double its elastic force by the further addition of heat in the respi- rator. 3. Steam exercised no chemical action upon the metal of the heating vessel and respirator, because the oxygen it contained was engaged by hydrogen, which latter had the stronger afllinity for it until a white heat was reached ; whereas the free oxygen of atmo- spheric air attacked iron and brass at much lower temperatures. 4. The specific gravity of steam was only about one-half that of atmospheric air at equal temperature and pressure ; moreover it was a far better conductor of heat, and both circumstances qualified it for rapid respirative action. 5. The fresh steam required for starting and sustaining the power of the engine was generated by heat that would otlierwise be lost. No air-pumps, &c., were required, and the management of the engine became as simple as that of an ordinary high-pressure steam-engine. 236 Dr. Bence Jones on Ventilatioti, [April 18, In conclusion, it was stated that at present there were several regenerative engines in constant practical operation, in this country (at the works of Messrs. Newall and Co., at Gateshead), in France, and in Germany, varying from five to forty horse power, which had proved the practicability of the principle involved, although they were still capable of improvement. Several other engines were now in course of construction at establishments celebrated for precision of execution, and with the advantage of Mr. Siemens' increased ex- perience in designing them. He had been fortunate to meet with men of intelligence and enterprise, lately joined together in a public company, whose co-operation insured a more rapid deve- lopement of his invention than individual effort could produce. The benefit he had hoped to derive from his discourse, incom- plete as it necessarily was, would be realized, if those men, eminent in science, whom he saw around him, would accept his labours as an earnest towards the practical realization of the dyna- mical theory of heat, and hasten its triumphs by their own re- searches. It was impossible to over-estimate the benefits that mankind would derive from a motive force at one-third or one- fourth part the cost and incumbrance of the present steam-engine. The total consumption of coal would certainly not diminish ; but our powers of locomotion and production would be increased to an extent difficult to conceive, tending to relieve men from every kind of bodily toil, and hasten the advent of the hoped for period of general enlightenment and comfort. [C. W. S.] WEEKLY EVENING MEETING, Friday, April 18. Sir Benjamin Collins Brodie, Bart. D.C.L. F.R.S. Vice- President, in the Chair. H. Bence Jones, M.D. F.R.S. M.R.I. PHYSICIAN TO ST. GEOKGE'S HOSPITAL. On Ventilation, and the means of determining its amount. In regard to all our wants, three questions constantly present them- selves. First, what it is exactly that we do want ; secondly, when have we got what we do want ; and thirdly, how to get what wc want. 1856.] and the Means of Determining its Amount. 237 We may know exactly the quality or quantity of bread and water that we want : we may see them measured or weighed, but how to get possession of them may still present many difficulties. So with our want of fresh air, the question. How much we want, and how to know when we have got enough, and no more than enough, is totally different from the question. How to get what air is wanted. It is not my intention to say anything now on the means of ventilation. I intend to bring before you the two other questions — partly, because I think that some error exists as to what is wanted, and much is required to be done by ^ood experiments to perfect our knowledge on this subject ; and partly, because the means of de- termining what air we have got is nowhere clearly stated. Usually the various sensations of individuals constitute the test of purity or impurity ; more rarely the rate of the passage of the air in or out of the room is determined ; and most rarely the chemical analysis of the air gives the amount of impurity which it contains. In- dependently of any of these methods it has been thought that measuring the cubic space in which we are breathing might suffice to tell us what air we have, and to let us know what air we want ; but it can be proved, in few words, that by the yard measure such questions cannot be determined. If a fish were confined under water in a glass tube open at the two ends, the time during which the fish would live in the tube would not depend on the cubic contents of the tube, but on the quantity of water caused to pass through the openings. So the cubic contents of a room will give no more information than the cubic contents of the glass tube. The rate of passage of the air, (or rather the rate and quantity of air which passes in,) which depends on the size of the openings, and on the difference of tem- perature within and without the room, is the important question. For the cubic contents which are enough or too much when one amount of ventilation exists, are quite insufficient when the ventila- tion is less ; that is, when the expired air is not sufficiently removed. Moreover, in a room which is constantly inhabited, the cubic space soon after the room is occupied ceases to be of importance, being entirely lost in comparison with the importance of the change of air or ventilation of the room. On the cubic space depends only how soon change of air will become requisite, but it does not at all influence the amount of change required. For example, if a single man constantly inhabit the largest room ; if it be perfectly closed, he will be poisoned in it just as certainly as in the smallest room, the difference will only be in the time required ; and whether in the small room or in the large room to live healthy he would require exactly the same amount of ventilation. The following table will prove that the cubic space actually given to persons in different circumstances is so different that no general rule can be true. 238 Dr. Bence Jones on Ventilation, [April 18, Varying Cubic Space. Cubic Feet. In a slave ship, with 311 persons 14 Best slave ships 28 Emigrant ships, upper deck . 90 „ lower do. 7ft. high 12G „ „ if under 173 H.M.S. Rodney (sleeping space) 76 „ Ariel 94 „ Ajax 98 „ Falcon 10# „ Severn 117 „ Py lades 125 „ Duke of Wellington . 128 „ Imperieuse . . . .1451 Hospitals, Dundee (old, now de-1 stroyed) ... .] „ Liverpool . . . „ Glasgow .... „ Walton (convalescent) „ Middlesex . . . „ Edinburgh . . . „ Haslar .... „ Westminster . „ Guy's (old wards) . „ Newcastle . . . „ Dundee (tiew) . , „ King's College . . „ St. Bartholomew's „ Guy's ('new wards) . „ London .... Cubic 398 561 7.50 800 1000 1090 1100 1200 1200 1500 1545 1600 1650 1700 1700 As a striking example of the error which prevails regarding the cubic space necessary for health, and as a good instance of the worthlessness of the appeal to practical experience, in many similar cases, I may give the following police regulation for lodging- houses : — " The space allowed in common lodging-houses for each lodger, in rooms from 5 ft. 6 in. to 6 ft. in height, is 50 superficial feet ; and in rooms more than 6 ft. in height, 30 superficial feet are allowed for each lodger. " This arrangement has been found to work satisfactorily, and to secure the health of the lodgers. Two children under 10 years of age are reckoned as one adult.'* Police Allowance in Lodging-Houses. When 5 ft, 6 in. to 6 ft. high, 50 superficial feet When 6 ft. 1 in. high, 30 „ 275 to 300 cubic feet.- 183 cubic feet. That is, rooms from 5 ft. 6 in. to 6 ft. high give from 275 to 300 cubic feet for each person; and if 6 ft. 1 in. high, then only 183 cubic feet are given. To obtain an equal amount of cubic feet of air the rooms should be between 9 and 10 ft. high. The police rule is, however, justified by experience ! " This arrangement has been found to work satis- factorily, and to secure the health of the lodgers." This does not prove the truth of the rule, but only that there is some great mistake in the rule. What rule then must be made ? It appears to me that instead of taking the cubic contents of a room as the guide, the ventilation and the square contents, or in other words, the change of air and the size of the floor, can alone determine the number of persons that can safely and properly be admitted into any space. 1856.] and the Means- of Determining its Amount. 239 As then we have learnt that a fixed amount of cubic space will not give us what air we want, or tell us what we have, we will turn to the question, How much air we do want, and how are we to know when we have got it ? According to the best experiments on Respiration, Man inhales 15,885 cubic inches of oxygen in 12 hours. 44 cubic feet of atmospheric air contain this oxygen. 3*7 per hour, = 0*06 cubic foot per minute. Man expires . . 1 60 cubic feet in 1 2 hours, containing 4 per cent carbonic acid If fresh air , .160 „ are added, there will be 2 per cent. If then fresh air . 320 „ are added, there will be 1 per cent. Hence, if a man has 640 „ in 12 hours, it will contam 1 per cent. = 53*3 „ per hour, = 0-88 per minute. == rather less than 1 cubic foot per minute. In other words, for diluting the carbonic acid we require 14^ times more air than for the supply of oxygen. In different ages, sexes, states, and conditions, the variation in these numbers is great, and no experiments have yet been made with human beings in the best and most natural conditions.* The following variations, obtained by single inspirations, may show how easily errors may be made — Effect of Rapid Breathing on the amount of expired Carbonic Acid. Number of expiration* Duration of each in Carbonic acid in 100 Constant amount of Propottioni in a minute. KcondB. voU. expiifld air. Carbonic acid. increase. 192 0-3125 2-6 2-6 0- 96 0-625 2-7 2*6 O'l 48 1-25 2-9 2-6 0'3 24 2*5 3«3 2-6 0'7 12 5-0 4M 2-6 1«5 6 lO-O 5'7 2«6 3*1 Effect of Holding the Breath on the amount of Carbonic Acid expired. Ordinary Respiration. Extraordinary deep Respiration. Br«athheld. Carbonic acid in expired air. Breath held. Carbonic acid in ezpind air. 20 seconds. 6-03 per 100 vols. 20 seconds. 4-80 per 100 vols. 25 „ 6-18 it 40 » 5-21 n 30 „ 6-39 » 60 n 6 '06 )» 40 „ 6-62 i> 80 f» 6-44 » 50 „ 6-62 » 90 » 6'50 n 60 „ 6-72 »» 100 »» 8-06 »» ♦ Even the experiments of MM. Regnault and Reiset on the respiration of animals, though perfect in their physical and chemical arrangements, are far from conclusive, in consequence of the physiological conditions to which the auimals were subjected. Vol. II. R 2iO Dr> Betice Jones on Ventilatiwis [April 18, Moreover, we have no accurate experiments to show the smallest quantity of carbonic acid that is injurious in tlie longest time. Is one per cent, of carbonic acid in air breathed for 12 hours injurious? Is half a per cent, injurious in 24 hours ? Is a quarter per cent, hurtful if breathed for 48 hours or longer ? Assuming that about one cubic foot of fresh air per minute gives to a man about one per cent, of carbonic acid in air he breathes — 2 cubic feet would give ^ per cent. (2i „ minimum, according to Vierort) . 3 to 4 „ Dr. Arnott considers insufficient , ^ to i „ 10 „ Dr. Reed advises ^ „ 20 „ Dr. Arnott advises 2 0 » Is then one part of carbonic acid in 2000 parts of air injurious when continually breathed? The atmosphere contains 3 parts carbonic acid in 10,000 parts of air when most pure, that is 1 part carbonic acid in 3333 parts of air. Hence Drs. Arnott and Reed have given the highest limit, whilst the lowest healthy limit is what we require to enable us to decide when we have got as much air as we want. From the best experiments, namely, those of M. Leblanc, I shall assume that air containing one per cent, of carbonic acid indicates such an impure state of atmosphere, that if breathed for 12 hours there will be an injurious action on the system; and that air containing half a per cent, of carbonic acid breathed continuously for 24 hours or more will probably prove hurtful. Whether at- mospheres having this amount of impurity are more injurious to women and children, though probable, is also unproved. Whether this amount of impurity, acting day after day, becomes more tolerated by the system is very doubtful. On all these questions much might be said, and much has yet to be done. But the question at present to be answered is. How are we to know when the air is thus far impure ? What means do we possess of determining the amount of ventilation in this or any other room ? There are three methods of obtaining this knowledge. The physiological method ; the physical method ; and the chemical method. 1. The physiological method consists in the determination of the action of the air of any room on its inmates, when well or when ill. The offensiveness of a room to a person just entering it, that is the action of the air on the sense of smell, is liable to great variations, depending on the observer himself. The nerves do not measure actual amounts of impression, but only variations arising from different degrees of impression ; and the action on the nervous system of one person is not a measure of the impression on the nerves of another person. Moreover, it is far from proved that the offensive smelling substances are poisonous. They may be more 1856.] and the Means of Determining its Amount 241 poisonous than carbonic acid, but we do not know that this is a fact. The best example I can give you of an animal substance in a stale of decomposition is musk, and yet it is no highly poisonous substance ; but even if these animal substances are not poisonous, still, as the offensiveness perceived by a person just entering from the fresh air bears an inverse proportion to the dilution of the air in the room by fresh air, the offensiveness to such a person may be taken as one test of the want of ventilation. Another part of the physiological method consists in determi- ning the general action of the air of the room on the body inside as well as outside, on the nerves, muscles, skin, and mucous mem- branes. Carbonic acid, in very large doses, immediately destroys life by stopping the breath, but of this rapid action there is no question. What we want to know is, — What is the action of the smallest injurious doses? Carbonic acid, like other poisons in small doses, is a medicine. We take it in soda water, and in effervescing medi- cines to allay irritation. It is used as a douche ; at first exciting the eyes or the nose, and soon allaying irritation. Like other medicines its effects vary with the age of the person taking it, with the time during which it is continued, with the strength of the dose, and with the peculiarities of the individual. A very small dose, long continued, will produce effects, whilst the same dose, in a short time, may give no perceptible result. The action of a full overdose may be well compared with the action of sether, of an overdose of alcohol, or of chloroform. At first irritation, then slight giddiness, intense giddiness, desire to vomit, excessive prostration, inability to make any muscular effort, syncope, death. The symptoms from small doses, long continued, closely resemble the symptoms from smaller doses of alcohol, long continued ; slowly the nutrition of the textures of the body is affected ; debility, unhealthy blood, passive congestions, low inflammations, especially of the mucous membranes, and broken skin, with ulceration and gangrene, are produced. If these effects are observed in any atmosphere, then the venti- lation is proved to be insufficient. 2. The physical method consists in determining the velocity of the air passing out of the room or into the room, either by calcula- tion or by experiment. The mean temperature of the air in the chimney is determined. Hence the increase in volume of the air is known. This volume of heated air is then compared with the volume of an equal weight of cold air. The difference in height in these two volumes of air is obtained, and the force of the draught is equal to the velocity which a heavy body would acquire by falling freely through this height. The velocity of a falling body, in feet per second, is equal r2 242 Di\ Bence Jones on Ventilation, [April 18, to eight times the square root of the number of feet in the fall. Hence the velocity of the air in the chimney per second is eight times the square root of the difference in the height of the two volumes of air. From this, the friction of the air in the chimney must be deducted ; this varies directly as the length, and as the square of the velocity, and inversely as the diameter ; usually from one-third to one-fourth, must be deducted, and then multiplying by 60 the velocity of the air per minute is found ; and multiplying the velocity per minute by the area of the chimney, the number of cubic feet of air discharged per minute is known ; that is, when the entrance of air is as free as the exit. Another method consists in determining the rate of motion of the air per minute by an anemometer, by multiplying the area of the narrower part of the chimney by the velocity, the number of cubic feet of air per minute passing out of the room may be ob- tained. The determination of the rate of motion of the air passing into the room is still more difficult ; no two openings into the room give the same velocity, even if they are the same size, unless the temperature of the air on the sides of the two openings is exactly the same. Moreover, in all the physical methods the temperature of the external air is constantly changing ; and the heat of the air in the chimney is liable to great variations ; and the occasional ventilation caused by opening the doors and windows interferes with the accurate determination of the amount of constant ventilation. Though the physical method alone is still very imperfect, yet, with the physiological method, it constitutes almost all the evidence that has hitherto been sought in doubtful cases. 3. The chemical method consists in weighing or measuring the products of combustion in -the room. These products are heat, water, and carbonic acid ; possibly small quantites of other sub- stances are produced, but they cannot be determined quantitatively. Moreover, the animal heat is so easily lost, and other sources of variations in the temperature so interfere with the measurement of the heat produced in the body, that it can afford no help. The amount of moisture in the room and in the internal air may be found by experiment ; and assuming that each adult man by respiration produces 3857 grs. of water in 24 hours, the quantity of moisture which would be present if the room were closed may be determined by calculation ; hence the quantity of air which has escaped may be known. The same method may be followed with the carbonic acid, which is a poison, and though it exists in the atmosphere still it is only in very small and nearly constant amount. Hence the chemical method mainly consists in determining how much carbonic acid exists in any space in a given time, when a 1856.] and the Means of Determining its Amount. 243 given number of people have remained in it. Then the quantity of carbonic acid which this number of people would produce in the given time must be calculated, and by deducting the quantity found, from the total quantity produced, the quantity of air which escaped from the given space in that time can be determined. The following examples from M. Leblanc's paper will best illustrate this method. M. Leblanc remained himself for ten hours in a perfectly closed atmosphere, the capacity of the chamber = 459 cubic feet (13 met. cube) ; this gave him less than one cubic foot of air per minute ( = 0 • 76 cubic foot). At the end of this time he found the car- bonic acid = 0.0075 in volume, or one part carbonic acid in one hundred and thirty-three parts of air. He found in a soldier's sleeping-room 25 men in a cubic space, which if perfectly closed would have given about 0*8 cubic foot per minute per man. Analysis gave 3 parts carbonic acid in 1000 air. Had the room been perfectly closed whilst they slept, there should have been 9 parts carbonic acid. Hence, 2' 4 cubic feet of air per minute had been given. In another sleeping room, with 52 soldiers, the capacity of the room would have given 0*6 cubic foot per minute, per man, 3 parts carbonic acid per 1000 were found ; if perfectly closed, there would have been 10 parts. Hence, about 2 cubic feet per minute had been given to each man. In a much smaller and worse ventilated room, with 1 1 soldiers and of capacity about 0*5 cubic foot per minute ^per man, nearly 9 parts of carbonic acid were found in 1000 air. If closed, there would have been 14 parts. Hence only 0*8 cubic foot of air per minute was given to each man. The method followed by M. Leblanc for determining the car- bonic acid was the following : — an aspirator which held about 43 pints of water had tubes fitted to it, for absorbing water and carbonic acid. In the course of one hour about 1 456 cubic inches, or • 844 cubic foot of air was drawn through the tubes by the escape of the water ; on weighing the tube which absorbed the carbonic acid in the second experiment mentioned above,*there was a gain of 2*62 grs. corresponding to 5' 2 cubic inches of carbonic acid. In his previous experiments on confined air, M. Leblanc used two large globes, holding each about 32 pints, which were ex- hausted and then filled with the air to be examined ; this was drawn through the absorbing tubes by two other exhausted globes. For my experiments on the close air in St. Pancras workhouse, I obtained a long tube, which, through the kindness of Mr. De la Rue, was accurately graduated ; this I filled myself with air in the rooms ; the tube was then closed and brought to the laboratory of the College of Chemistry, placed over mercury, and potass bulbs were introduced by Mr. Witt, and the height of the mercury noted. After 12 hours, the height was again noted, and by corrections for 244 Dr. Bence Jones on Ventilation, [April 18, the temperature and pressure, the absorption of the carbonic acid was determined. Thus, In one room there was 1*14 per cent, in volume of carbonic acid. In another „ 2 '75 and 2*02 „ „ In another „ 1'8 „ „ In another „ 1*6 „ „ The absorption is so small, and the corrections so considerable, that it would be far more desirable, instead of measuring the result, to determine the carbonic acid by weight, if a convenient apparatus could be constructed. Through the kindness of Mr. Defries, I am enabled to show you a gas meter, which, by the action of a falling weight, draws the air through an absorbing apparatus, and registers the amount of air which has passed through. By weighing the absorbing apparatus before and after the passage of the air, the amount of carbonic acid may be determined ; and by noting the index of the register, the amount of air in which this carbonic acid was present can be known. If another gas meter were placed before the absorbing apparatus ; that is, if an absorbing apparatus were placed between two gas meters, when the air was passed through both meters, the difference in the two registers would give the measure of the amount of car- bonic acid, whilst the weight of the carbonic acid might also be determined by weighing the absorbing apparatus. It must be remembered that carbonic acid may not be the sole poison in expired air ; and an accurate investigation is yet wanting to show what other substances are injurious, and how they may be best determined quantitatively. When this is done, but not till then, as in our supply of water, so in our supply of air, we shall cease to trust to a physiological or physical method of enquiring what we want or what we have got, but we shall rely on chemistry to deter- mine the purity of the air we breathe, just as much as we now trust to it for determining the quality of the water which we drink. 1 might in conclusion point to this statement, given to me by a physician to a lying-in-hospital — Mortality of Mothers. Deathi, During 4J years, before systematic ventilation 60 During 7 years, with Dr. Reed's system of ventilation .... 9 During 4 years again, without it .... , 24 Mortality of Children. During 5i years, with the ventilation 6 During 4 years, without it 36 But some other causes might be thought to produce this result. I will therefore pass on to the question — Why do we want ventilation ? Why do we want fresh air ? 1856.] and the Means of Determining its Amount. 245 Why do we want to take in oxygen ? and why do we want to get rid of carbonic acid ? Shortly, we want oxygen, because of its chemical energy. It is the main spring of our life. On it the production of animal heat depends, and the vital powers — sensation and motion, no less than nutrition and secretion, are directly influenced by its action. Why do we want to get rid of surrounding carbonic acid ? Literally, because the carbonic acid stops the way, and prevents the escape of newly formed carbonic acid from within. If we were placed in an atmosphere containing as much carbonic acid as exists in the lungs, the carbonic acid of the atmosphere would not pass from the lungs to the blood and act as a poison, but that carbonic acid which was passing out from the blood would stop in the lungs and prevent more from escaping out of the blood, and that carbonic acid which was formed in the body would act as a narcotic poison. From experiments on animals it appears, that the air must contain 20 per cent, of carbonic acid before absorption of that gas by the blood is observed. Moreover the escape of gases from the blood affects the circulation of the blood. In sudden death from suffoca- tion, the side of the heart which throws the blood to the lungs is found distended, whilst the side which throws the blood from the heart is empty, there has been an obstruction to the flow. By stop- ping respiration and causing pressure we can stop the pulse and the heart's sounds and impulse when we please. This experiment is easy to make. There can be no doubt that this is more the result of pressure than of any arrest of escape of carbonic acid. I mention it only as a striking evidence how suddenly the action of the heart may be influenced by the respiration. When the escape of carbonic acid from the blood is retarded or prevetited, the want of ventilation of the blood causes more or less stoppage of the blood in the vessels, and makes the blood a narcotic poison to all the tissues with which it is in contact. We may consider oxygen as our most necessary food, and car- bonic acid as the refuse which passes into our sewers. We have all probably come to the full belief that a house badly drained causes disease and death ; but we hardly yet fully admit to ourselves that a house or body without good means of ventilation is a house or body badly drained. At present our chimneys are our chief aerial drains, which almost cease to act as soon as the temperature outside and inside the house is the same ; and even when these drains are in action, we are unwilling to think that that fire which so cheer- fully ministers to our warmth, like most human contrivances for doing two things at once, does neither well. [H. B. J.] 246 Br, Sandwith on the [April 21, EXTRA EVENING MEETING, Monday, April 21. The Duke of Northumberland, K.G. F.R.S. President^ in the Chair. Humphry Sandwith, M.D. CHIEF OF THE MEDICAL STAFF AT KARS, On the Siege of Kars. On the breaking out of the war in 1854, Dr. Sandwith, residing at Constantinople, left that city for the Danube, and went through a campaign. In the autumn of the same year he was appointed to the staff of General Williams, and shortly after joined him at Erzeroom. In June, 1855, he accompanied him to Kars. They found the defences of the city much strengthened by the exertions of Colonel Lake, aided by Captains Thompson and Teesdale. On June 18, General Mouravieff, with an army of 40,000 infantry and 10,000 cavalry, came in sight of the city. The army of the besieged consisted of 15,000 men, with only three months' food, and three days' ammunition; nevertheless in a short time, by the energy, skill, firmness, and kindness of General Williams and his staff, the enthusiasm of the defenders of Kars was so thoroughly roused as to enable them to endure, with patient heroism, the sufferings of this protracted siege, so greatly aggravated by disease and deficient resources. The first skirmish with the enemy took place on June 14. On July 15, Kars was thoroughly blockaded ; and the Russian camp drew nearer and nearer. Mouravieff reconnoitred Erze- room, but returned to Kars early in August. In his absence the Russians attacked the place, but were repulsed with severe loss (August 7) . On the 8th of September the suft'erings of the besieged were greatly relieved by the discovery of a quantity of secreted corn ; but on the 25th the cholera broke out. The grand assault on the place by the Russian army took place just before break of day, on the 29th of September. The western extremity of the works named Tahmasp was attacked simultaneously with the line of forts in the rear of the town called the English batteries. These last being entrusted chiefly to irregular troops were carried, and the Russians commenced shelling the town from this position. In about three hours, however, tlie enemy being 1856.] Siege of Kars. 247 attacked in both flanks, and menaced in front, was obliged to retire, having suffered severely ; but he still persisted in his attacks on Tahmasp, which continued almost without intermission for seven hours. This position was defended by General Kmety and Major Teesdale ; and the troops were mainly riflemen, armed with the carabin d, tige. About noon the enemy retired, leaving upwards of 6000 dead under the breastworks and batteries of Kars. General Williams, from the centre of the camp, directed each grand move- ment during the day. Dr. Sandwith stated his belief, that if General Williams had had 2000 cavalry, the enemy would have been totally defeated and dispersed. The Russian cavalry, 10,000 strong, having scarcely suffered during the assault, was enabled to keep up the blockade ; so that the state of the garrison, suffering from cholera and famine, became hopeless. In the later days about 100 of the troops alone died of famine, while the condition of the townspeople was desperate in the extreme ; the carcasses of dead animals were torn from their graves and devoured by the men, women, and children, while the grass in all the open spaces was torn up to be eaten. When human nature could endure no longer, it was resolved to capitulate. On November 25, General Williams and his aide-de-camp Teesdale, rode over, under a flag of truce, to the Russian camp. They were well received by Mouravieff". General Williams told his chivalrous enemy that he had no wish to rob him of his laurels ; the fortress contained a large train of artillery, with numerous standards, and a variety of arms : but the army had not yet sur- rendered, nor would it without certain articles of capitulation. ** If you grant not these," added the General, " every gun shall be burst, every standard burnt, every trophy destroyed, and you may then work your will on a famished crowd." "I have no wish," answered Mouravieff", " to wreak an unworthy vengeance on a gallant and long-suffering army, which has covered itself with glory, and only yields to famine. Look here," he exclaimed, pointing to a lump of bread, and a handful of roots, " what splen- did troops must these be, who can stand to their arms in this severe climate on food such as this ! General Williams, you have made yourself a name in history ; and posterity will stand amazed at the endurance, the courage, and the discipline which this siege has called forth in the remains of an army. Let us arrange a capitula- tion that will satisfy the demands of war, without outraging humanity." The terms of capitulation were briefly as follows : — " The officers and soldiers of the regular army were to pile arms in camp, and march out with their music and colours, and surrender them- selves prisoners of war to the Russian army, retaining their swords. All private property, the castle, mosques, and other public build- ings, are to be respected, and the inhabitants protected from pillage 248 Mr. W. B. Donfie [April 25, or insult. The militia, the Bashi-Bozooks, are allowed to depart unarmed to their homes. The medical corps, and other non- combatants, are to be released and be free to serve again in any other army. A certain number of foreign officers, and the subjects of states not at war with Russia, are to be allowed to depart, on condition of not serving again during the continuance of the war." On the 27th, General AVilliams and his staff dined with the Russian general. Even in their desperate circumstances, the capitulation was received by the army with great lamentation. Dr. Sandwith left Kars on November 30, and arrived in London on the 9th of January, 1856. [H. S.] WEEKLY EVENING MEETING, Friday, April 25. Sm Benjamin Collins Brodie, Bart. D.C.L. F.R.S. Vice-President, in the Chair. W. B. Donne, Esq. On the Works of Chaucer^ considered as Historical Illustrations of England in the \Ath Century. Mr. Donne commenced his discourse with some remarks on the changes which the language and literature of England had under- gone since the age of Edward III. In the period of time which elapsed between Chaucer's birth and death, 1328 — 1400, occurred some of the most striking and stirring events in English history. It includes the reigns of Edward III. and Richard II., and the opening scenes of the usur- pation of the House of Lancaster. It comprises Edward's French and Scottish wars — his league with Jaques van Artevelde and the men of Ghent— so important at the time and in its consequences to English commerce and manufactures, — the battle of Crecy, where the Black Prince won his spurs, the battle of Poictiers, where he approved himself a soldier fit to stand by Caesar and give direction. Chaucer may possibly have been among the crowd that welcomed that prince when he rode beside John of France through the streets of London to the palace of Westminster ; he may have been among the spectators of the banquet at which Edward enter- tained the three captive majesties of France, Scotland, and Cyprus. 1856.] on Chaucer i his Age and Works. 249 Perhaps to Chaucer not the least interesting result of these wars was the presence of those Proven9al minstrels, who came in the train of the Black Prince. Nor was the reign of Richard II. un- propitious to men of letters. The court was gay, but refined ; the monarch, though unwise, was not unlettered. He patronised Gower, and was not unmindful of Gower*s pupil and friend. There was a rising, too, of the commonalty in this reign, not unmarked by Chaucer, who employs it as an image of rural confusion. There was banding of the country-party against the courtiers : schisms in the country-party itself. Harry of Lancaster's banishment and re- turn, afterwards chronicled by Shakspeare in scenes " Sad, high, and working full of state and woe Such noble scenes as draw the eye to flow." A king discrowned and swiftly or lingeringly murdered, and the seeds sown of the great barons' war, which, before another half century had passed away, convulsed England from the Exe to the Tweed. It was a change not much noted at the time, yet fraught with conse- quences more durable than the humiliation of France, that in Edward's reign the laws began to speak in the English tongue, and the power of the minor barons, afterwards the Commons of England, to be felt in Parliament. It wa^ a movement much noticed at the time, yet without perception of its full results, that Wickliffe was not merely permitted to assail the doctrine and discipline of the church, but was also encouraged in his assault by the first prince of the blood, and by some of the foremost men in the realm. Of this period Chaucer was for at least sixty years an attentive observer, and latterly an accurate chronicler. In its movements he took part to a degree unusual with poets : and when not taking part was taking notes of this brave, bustling, and youthful people of England. And his opportunities for observation were most favour- able. Were we to seek for a capable historian of an age we should be inclined to repeat Agur's prayer — " Give him neither poverty nor riches." Too highly placed, the observer is captived by the prejudices of his rank : too lowly, his field of contemplation is narrowed. Chaucer occupied a middle position. He was connected by birth with the middle order; by marriage with the higher; his employments brought him into contact with the people ; his gifts and his learning rendered him an acceptable companion to the most cultivated persons of his age. His occupations, at different periods of his life, were well adapted to his functions as the chroni- cler of manners. As Commissioner of Customs, he was enabled to study the commercial classes ; as Clerk of the Works and Ranger of the Royal Forests, he was familiar with artisans and husbandmen. His military service acquainted him with camps ; his diplomatic missions with cabinets. That he was the most observing of all observers is plain from the Prologue to his " Canterbury Tales." 250 Mr. W. B. Donne [April 25, The speaker next observed it was not surprising that the bio- graphy of Chaucer was scanty and doubtful. Little is known of Shakspeare and his contemporaries ; although, when they flourished printing was common, and the great writers of the age were either, like Raleigh and Sidney, the most distinguished of public men, or like Heywood, Shakspeare, and Jonson, constantly before the public either as actors or authors. Whereas Chaucer, and his contempora- ries, wrote sixty years before Caxton set up the first printing-press at Westminster, and there was no theatre to diffuse and perpetuate their fame, and few readers to take an interest in their writings. Enough, however, is ascertained of Chaucer's history to warrant us in describing him as a " courtier, soldier, and scholar." A courtier. — If Edward III. were not a very zealous patron of literature, he was a favourable and'fostering friend to Chaucer himself. Perhaps he owed his promotion, in some degree, to a fortunate marriage. John of Gaunt and Chaucer espoused two sisters, the daughters of Sir Payne Roet, a native of Hainault, and Guienne King-of-arms. The poet thus came under the immediate notice of Queen Philippa of Hainault, and of the Duke of Lan- caster. The Duke's regard for his wife's sister was manifested by a pension, by occasional presents, and her husband's advancement. In 1367 Chaucer was made one of the valets of the king's chamber, in 1370 he was employed in the king's service abroad, and towards the end of 1372 he was one of a commission to determine upon an English port where a Genoese commercial establishment might be formed. On this occasion he visited Florence and Genoa. In 1374 he was appointed Comptroller of the Customs in the port of Lon- don ; and soon afterwards sent, in association with Sir Thomas Percy (afterwards Earl of Worcester), on a special mission to Flanders. In 1386 he sat in Parliament as Knight of the Shire for Kent, and although he latterly met with reverses, and fell with the Lancaster party for a time, yet on the accesion of "high- mounting Bolingbroke " he enjoyed at the last the full sunshine of royal favour. As he does not appear to have been a very zealous soldier, so it is probable that he was not a very active partisan. Though, like the great Florentine, driven by his political enemies into banishment, he expends on them no withering sarcasms, and even his occasional allusions to seasons of adversity are steeped in good humour. A soldier. — In Chaucer's age the tonsure of the priest was almost the only mode of exemption from the bearing of arms, and both gentleman and churl would have been deemed recreant had they eluded their term of military suit and service. From Chau- cer's own testimony, it is known that in the autumn of 1359 he accompanied that gallant and well-appointed army with which Edward III. invaded France. This was apparently the first and last of the poet's campaigns. It was ill adapted to stimulate his military ardour, if, indeed, he possessed any, for the expedition was 1856.] on Chaucer y his Age and Works. 251 nearly equally disastrous to the invaders and the invaded ; pestilence and famine paged the heels of the English host, and no crowning victory like Crecy compensated for the loss and discredit of the expedition. Chaucer himself became for a while the inmate of a French prison. He was released at the Peace of Bretigny, or Chartres, in the following year. From the internal evidence of his writings it is probable that the trade of war was not much to his taste. Neither the Norman- French poets, from whom he borrowed so largely in his earlier writings, nor the romance writers of the 12th and 13th centuries, imparted to him their Homeric fondness for stricken fields and blazing towns. Complying, indeed, with the customs of literature as he found them established, he occasionally describes passages of arms, and the gests and graces of the tournament. But he does not dwell with any zest upon such themes, and forsakes them wil- lingly for more peaceful subjects. Like Horace, he left to more ambitious bards the spirit-stirring drum and the ear-piercing fife. He was, and doubtless knew himself to be, the poet of nature and her aspects ; of man and social life ; of the foibles and virtues of his age. When he compliments his patrons in what may be termed his laureate productions, he takes for his topics of congratulation or condolence a courtship or a marriage, the loss of royal favour, or a death. Their achievements in Poitou and Picardy are uncelebrated by him. Yet that during his brief military career Chaucer was no idle or incurious observer of the life in camps, appears throughout the " Knight's Tale," and many passages in his other writings, wherein both the ardour of battle and its image, the tournament, are aptly delineated. The description of the preparation for combat in the lists is worthy to stand very near Shakspeare's better known description of the eve of battle. Compare Chaucer's " Knighte's Tale"— ** And on the morwe whan the day gan spryng Of hors and hameis, noyse and clateryng." with Shakspeare's Henry V. Act iv. Chorus. A scholar. — From an allusion in one of his early poems* it has been inferred that Chaucer was educated at Cambridge. Leland, who had good sources of information, says that he was of Oxford, and that he finished his studies at Paris. It is not impossible that each of these universities may in its turn have enrolled the name of Chaucer on its boards. At a time when colleges were little more than grammar-schools it was not unusual for students to migrate from one university to another, in quest of knowledge or attracted • Court of Love. — '* My name, alas ! my herte why makes thou straunge, Philogonet I call'd am far and neere Of Cambridge clerk," &c. 252 Mr, W, B, Bonne, [April 25, by the fame of particular professors. Bologna was second to no school in its day, yet both Dante and Petrarca visited Paris for the purpose of better instruction than their own country afforded. Under whatever auspices, however, or in whatever place Chaucer prosecuted his studies, the extent of his acquirements is testified by his works and the applause of his contemporaries. Besides the lore most attractive to him, the chivalrous bards of the 13th century, and the Proven9al minstrels, he was well versed in the theology, philosophy, and scholastic learning of his age. Such science as was then known he had acquired ; and it is agreeable to discover that, like Milton, he contributed to the education of the young, since he addressed his " Conclusions of the Astrolabie " to his son " little Lewis." He lived too early, and it was perhaps fortunate that he did so, to be affected by the discovery of ancient manuscripts in the 15th century. The speaker then briefly surveyed some of the characteristics of Chaucer's diction : to the effect that — it is the language alone of Chaucer which renders him antique or obscure, and even then but partially so : for there still lingers in much of his diction the same vernal brilliance that irradiates his pictures of life and manners. As regards verse absolutely, and prose partially, Chaucer was the workman who forged the tools with which he wrought. He took the English language indeed as it was used in his time, and as every true poet will do in its best estate at that time. But what was the estate of the English language in the 14th century? What was the coin ready-minted to Chaucer's hands ? For the learned and all ecclesiastical purposes the Latin was still a living speech ; French was generally employed at court, in noble households, and epistolary correspondence. It had but recently ceased to be the language of statute law and legal procedure. With the mass of the people the Anglo-Saxon remained in use, mutilated indeed of many of its inflections, and passing rapidly into that tertiary form which is the characteristic of the English language. From all these elements Chaucer welded together an idjom which retains a portion of each of them : its bones and sinews being Anglo-Saxon ; its integuments and complexion, Latin or romantic. The difficulty of Chaucer's language arises not from any affecta- tion of antiquity on his part, nor from the corruptions of his manu- scripts, nor from any total revolution in the English tongue, re- moving his poems into the region of Middle English or Anglo- Saxon. He is often hard to be understood, simply because his idiom is nearly as much his own creation as the joyous, pathetic, and passionate images with which his writings abound. There is, perhaps in all literature nothing more remarkable than Chau- cer's language. It is, strictly speaking, neither a living nor a dead language ; it must not be fettered by syntactical rules, nor tried by common usage. Of these peculiarities the condition of the English tongue in Edward III.'s time was in some measure 1856.] on Chaucer, his Age and Works, 253 the cause. In the first place the area of book-language was very limited : while the dialectic varieties of speech were very numerous. English was then imperfectly understood in the Celtic districts of the island : north of the Ilumber, and in East Anglia, it was encountered by a Danish patois. It was further circumscribed by the general employment of French by the nobles, and of Latin by ecclesiastics. Political motives, indeed, induced Edward to encourage the use of the English tongue in the courts of justice, and among his courtiers and attendants ; but there is no evidence of his having been, as his grandson Richard really was, a patron of literature. Chaucer and Langland are the two principal witnesses for the silent revolution which our language was undergoing in the 13th and 14th centuries. It is curious, that at the time when the author of the " Vision of Piers, the Ploughman," was labouring to re- invigorate our speech with Saxon forms, the author of the " House of Fame," was entering upon his task of enriching it with a foreign vocabulary, and moulding it to a spirit and forms of expression different from either of its original components. Doubtless a similar feeling of dissatisfaction with the existing state of the English language led William Langland to his Saxon archaisms, and Geoffery Chaucer to his French and Provencal innovations. The mightier genius proved himself to be the wiser workman of the two. Langland's poem is studied by philologers alone ; Chaucer's writings began a new era in English literature, and his influence has been felt and acknowledged by every successive generation of English poets. It is still an unsettled question whether Chaucer were acquainted with the literature and learned men of Italy. Sir Harris Nicolas doubts it without sufficient reason, and in despite of Chaucer's own assertions. With the writings of Dante, he was evidently well acquainted, and distinctly quotes from him more than once. The sentence cited by him in the " Wyf of Bathe's Tale," is almost a literal translation from the Italian : — " Wei can the wyse poet of Florence That hatte Daunt speke of this sentence ; Lo, in such maner of rym is Dauntes tale : Fui seeld uprisith by his braunchis smale Prowes of man, for God of his prowesse Wot that we claime of him our gentilesse."* It is not so certain that Chaucer visited Petrarch at Padua, since the statements of Speght and Urry rest wholly on surmises ; and it • Compare "Purgatorio," vii., 121 :-- " Kade volte risurge per li rami L' humana probitate; et questo vuole Quei che la da, perche da se si chiami." 254 Annual Meeting. [May 1, is doubtful whether the following lines from the " Prologe to the Clerk of Oxenford's Tale," refer to the poet himself, or the original narrator of the story. " I will yow telle a tale, which that I Lerned at Padowe of a worthy clerk As proved by his wordes and his werk Frances Petrark, the laureat poete Highte this clerk, whos rhetorique swete Enlumynd all Ytail of poetrie." It would be rash to expect that Chaucer will ever regain his position as a national favourite. All that we can claim for him is •the recognition of his surpassing worth as an adjunct to the chro- niclers of his age, as standing, both by right of time and right of power, in a similar relation to English literature with that of the *' all Etruscan three " to Italian, as no less worthy than Petrarch himself of the laurel crown. His vigour and freshness are, like nature herself, perennial ; his powers of observation have never been surpassed ; his vein of humour and portraiture of manners have been exceeded by Shakspeare alone. He is not only the most conspicuous, but also the sole intellectual representative of England in the 14th century, and his true and lively pictures of its men and manners render the dry bones of its chronicles still capable of receiving form, motion, and life. In his own words, slightly mo- dified— *' Though he be hoar, he fares as doth a tree That blossometh ere the fruit y-waxen be : The blossomy tree is neither dry nor dead ; He feeleth nowhere hoar but on his head; His hearte and all his limbes be as greene As laurel through the yeare is for to seene." [W. B. D.] ANNUAL MEETING, Thursday, May 1. The Duke of Northumberland, K.G., F.R.S., President, in the Chair. The Annual Report of the Committee of Visitors was read, and adopted.— It states that the account of Expenditure for 1855 has been duly examined, and the several items thereof compared with the vouchers ; and that the Receipts continue in a satisfactory state, the Annual Contributions being equal to those of 1854, and superior to any former year ; while the compositions received from Members, in lieu of future annual payments, have been above the average number. The surplus income beyond the expenditure has 1856.] A?inuai Meeting, 265 enabled the IManagers to invest £600 in the purchase of stock, besides the usual annual additions to the Accumulating Funds of the Institution ; and the property of the Royal Institution, including the house and furniture, the library, &c., and the sums invested in the public funds, now amounts to about Fifty Thousand Pounds. The presence of His Royal Highness Prince Albert on several occasions, and of the Prince of Wales and Prince Alfred at the whole of the juvenile course oi 1855-56, was adverted to. A List of Books Presented (amounting in number to 300 vol- umes,) accompanies the Report, making a total, with those purchased by the Managers and Patrons, of 743 volumes (including Periodi- cals) added to the Library in the year. Thanks were voted to the President, Treasurer, and Secretary, to the Committees of Managers and Visitors, and to Professor Faraday, for their services to the Institution during the past year. The following Gentlemen were unanimously elected as Officers for the ensuing year : — President — The Duke of Northumberland, K.G. F.R.S. Treasurer— William Pole, Esq. M.A. F.R.S. Secretary — Rev. John Barlow, M.A. F.R.S. Managers. William H. Blaauw, Esq. M.A. F.S.A. Sir Benjamin Collins Brodie, Bart. D.C.L. V.P.R.S. Thomas Davidson, Esq. Warren De la Rue, Esq. Ph.D. F.E.S. George Dodd, Esq. F.S.A. Sir Charles Fellows. W. R. Grove, Esq. M.A. Q.C. F.R.S. Lieut.-Col. F. Vernon Harcourt, M.P. Henry Bence Jones, M.D. F R.S. George Macilwain, Esq. Sir Roderick I. Murchisow, G.C.S- D.C.L. F.R.S. Frederick Pollock, Esq. M.A. Joseph William Thrupp, Esq. Sir James Shaw Willes, Justice of the Common Pleas. Col. Philip James Yorke, F.R.S. Visitors. Francis Bayley, Esq. John Charles Burgoyne, Esq. John Robert F. Burnett, Esq. Hugh W. Diamond, M.D. F.S.A. Gordon W. J. Gyll, Esq. Thomas Henry, Esq. John Hicks, Esq. John Holdship, Esq. M.A. R. Reginald I. Morley, Esq. Thomas N. R Morson, Esq. The Viscount Ranelagh. Joseph Skey, M.D. Rev. William Taylor, F.R.S. Hensleigh Wedgwood, Esq. M.A. Thomas Young, Esq. The President nominated the following Vice-Presidents fi)r the ensuing year : — W. R. Grove, Esq. H. Bence Jones, M.D. W. Pole, Esq , Treasurer. Rev. J. Barlow, Secretary Sir B. C. Brotiic. Sir Charles Fellows. Sir R. I. Murchison. Vol. II. 256 Professor Owen, on the Ruminant Quadrupeds, [May 2, WEEKLY EVENING MEETING, Friday, May 2. The Duke of Northumberland, K.G. F.R.S. President, in the Chair. Professor Owen, F.R.S. On the Ruminant Quadrupeds and the Aboriginal Cattle of Britain. The speaker introduced the subject of the Ruminant order of quadrupeds, and the source of our domesticated species, by some general remarks upon the classification of the class Mammalia, and on the characters of the great natural group defined by Ray and Linnaeus as the Ungulata, or hoofed mammalia. These are divisible into two natural and parallel orders, having respectively the Anoplotherium and Palceotherium as their types, which genera, as far as geological researches have yet extended, were the first, or amongst the earliest, representatives of the Ungulata on this planet. The brilliant researches by Baron Cuvier, the founder of palseontological science and the reconstructor of those primeval hoofed animals, from fragmentary fossil remains in the gypsum quarries at Montmartre, were alluded to. Diagrams of the entire skeletons of the anoplotherium and palaeotherium were referred to, in illustration of their dental and osteological peculiarities. The Anoplotherium, with the typical dentition of . . 3-3 . 1-1 7 4-4 , 3-3 .. incisors - — -, canines . — -, premolars - — -, molars - — - = 44, 0"~o 1 -^ 1 4— -4 o — o had all its teeth of the same length, and in a continuous unbroken series : this character is peculiar to man in the existing creation. The PalcBOtherium, with the same dental formula as the Anoplo- therium, had the canines longer than the other teeth, and developed into sharp-pointed weapons ; necessitating a break in the dental series to receive their summits in closing the mouth. The anoplotherium had 19 vertebrae between the neck and 1856] and the Aboriginal Cattle of Britain. 257 sacrum, viz., 13 dorsal, and 6 lumbar. The palaeotherium had 16 dorsal, and 7 lumbar vertebrae. The anoplotherium had a femur with 2 trochanters, and the fore-part of the ankle-bone, called "astragalus," divided in 2 equal facets. Its hoofs formed a symmetrical pair on each foot. Cuvier has very justly inferred that its stomach must have been complex, and probably, in some respects, like that of the camel or peccari. The palaeotheriiun had a femur with 3 trochanters, an astragalus with its fore-part unequally divided, and hoofs, 3 in number, on each foot. It most probably had a simple stomach, like the tapir and rhinoceros, which, amongst existing animals, most nearly resemble that extinct primitive hoofed quadruped, with toes in uneven number. Every species of ungulate mammal with an uneven number of hoofs or toes, that has been introduced into this planet since the eocene tertiary period, whether it have 1 hoof on each foot, as in the horse, 3 as in the rhinoceros, or 5 as in the elephant, resem- bles the palaeotherium ^in having more than 19 dorso-lumbar ver- tebrae, which vertebrae also differ in number in diflferent genera ; 22^ e.g. in the rhinoceros, 23 in the mastodon, 27 in the hyrax. The typical pachyderms, with an odd number of hoofs, have also three trochanters on the femur, 'the fore-part of the astragalus unequally divided, and the pattern of the grinding surface of the molar teeth unsymmetrical, and usually crossed by oblique enamel ridges. All the existing odd-toed or perissodactyle mammals have a simple stomach, and a vast and complex caecum ; the horned species have either a single horn, or two odd horns, one behind the other on the middle line of the head, as, e.g., in the one-horned and two horned rhinoceroses. Every species of ungulate animal with hoofs in even number, whether 2 on each foot, as in the giraffe and camel, or 4 on each foot, as in the hippopotamus, resembles the anoplotherium in having 19 dorso-lumbar vertebrae, neither more nor less ; in having 2 trochanters on the femur, in having the fore-part of the astragalus equally divided, and in having the pattern of the grinding surface of the molar teeth more or less symmetrical. The homed species have the horns in 1 pair, or 2 pairs. All have the stomach more or less complex, and the caecum small and simple. In the hog the gastric complexity is least displayed ; but in the peccari the stomach has 3 compartments ; and in the hippopotamus it is still more com- plex. But the most complex and peculiar form of stomach is that which enables the animal to " chew the cud," or submit the aliment to a second mastication, characteristic of the large group of even- hoofed Ungulata, called " JRuminantiaJ^ These timid quadrupeds have many natural enemies ; and if they had been compelled to submit each mouthful of grass to the full extent of mastication which its digestion requires, before it was swallowed, the grazing ruminant would have been exposed a s2 258 Professor Owen, on the Ruminant Animals, [May 2, long time in the open prairie or savannah, before it had filled its stomach. Its chances of escaping a carnivorous enemy would have been in a like degree diminished. But by the peculiar structure of the ruminating stomach, the grass can be swallowed as quickly as it is cropped, and be stowed away in a large accessory receptacle, called the " rumen," or first cavity of the stomach ; and this bag being filled, the ruminant can retreat to the covert, and lie down in a safe hiding-place to remasticate its food at leisure. The modifications of the dentition, aesophagus, and stomach, by which the digestion in the ruminantia is carried out, were described and illustrated by diagrams. The speaker next treated of the various kinds of horns and antlers ; the manner of growth, shedding, renewal, and annual modi- fications of the deciduous horns, the peculiarities of the persistent horns, the mechanism of the cloven foot ; and the provision for maintaining the hoofs in a healthy condition, were pointed out. The following were the chief varieties of the ruminating stomach. In the small musk-deer ( Tragulus), there are three cavi- ties, with a small intercommunication canal between the second and last cavity ; the " psalterium," or third cavity, in the normal rumi- nating stomach, being absent. This cavity is likewise absent in the camel-tribe, which have the cells of the second cavity greatly enlarged, and have also accessory groups of similar cells developed from the rumen, or first cavity. These cells can contain several gallons of water. The relation of this modification, and of the hump or humps on the back, to the peculiar geographical position of the camel-tribe, was pointed out. The modifications of the ruminating stomach, the discovery of rudimental teeth in the embryo Ruminantia, which teeth (upper incisors and canines) have been supposed to characterize the pachy- derms ; the occurrence of another alleged pachydermal character, viz. the divided metacarpus and metatarsus in the foetus or young of all ruminants, and its persistence in the existing Moschus aquations, and in a fossil species of antelope ; the absence of cotyledons in the chorion of the camel-tribe, with the retention of some incisors as well as canines in the upper jaw of that tribe ; the ascertained amount of visceral and osteological conformity of the supposed circumscribed order Ruminantia, with the other artiodactyle (even- toed) ungulata ; above all, the number of lost links in that inter- esting chain which have now been restored from the ruins of former habitable surfaces of the earth — all these and other similar facts have concurred in establishing different views of the nature and value of the ruminant order from those entertained by Cuvier, and the majority of systematic naturalists up to 1840. Thus instead of viewing the Anoplotherium as a pachyderm, the speaker, having regard to the small size of its upper incisors and canines, to the retention of the individuality of its two chief metacarpal and metatarsal bones, and to the non-development of horns at any 1856.] and the Aboriginal Cattle of Britain. 259 period of life, would regard it rather as resembling an overgrown embryo-ruminant — of a ruminant in which growth had proceeded with arrest of development. The ordinal characters of the ano- plotherium are those of the Artiodactyla. On the other hand, instead of viewing the horse as being next of kin to the camel, or as making the transition from the pachyderms to the ruminants, the speaker had been led by considerations of its third trochanter, its astragulus, its simple stomach, and enormous sacculated caecum, the palaeotherian type of the grinding surface of the molars, and the excessive number of the dorso-lumbar vertebrae, to the conviction of the essential affinities of the Equidca with otlier perissodactyles (odd-toed hoofed beasts). The primitive types of both odd-toed and even-toed ungulates occur in the eocene tertiary deposits : the earliest forms of the ruminant modification of the Artiodactyla appear in the miocene strata. The fossil remains of tlie aboriginal cattle of Britain have been found in the newer pliocene strata, in drift gravels, in brick- earth deposits, and in bone-caves. Two of these ancient cattle (Bovidce) were of gigantic size, with immense horns ; one was a true bison (Bison prisons), the other a true ox (Bos primigenius) ; contemporary with these was a smaller species of short-horned ox (Bos longifrons), and a buffalo, apparently identical in species with the Arctic musk- buffalo (Bubalus, or Ovibos, moschatus). The small ox (Bos longifrons) is that which the aboriginal natives of Britain would be most likely to succeed in taming. They possessed domesticated cattle (pecora) when Caesar invaded Britain. The cattle of the mountain fastnesses to which the Celtic population retreated before the Romans, viz. the Welsh " runt " and Highland " kyloe," most resemble in size and cranial characters the pleistocene Bos Icmgifrons. Prof. Owen, therefore, regards the Bos longifrons^ and not the gigantic Bos primigenius, as the source of part of our domestic cattle. From the analogy of colonists of the present day he proceeded to argue that the Romans would import their own tamed cattle to their colonial settlements in Britain. The domesticated cattle of the Romans, Greeks, and Egyptians bore the nearest affinity to the Brahminy variety of cattle in India. As the domestic cattle im- ported by the Spaniards into South America have, in many loca- lities, reverted to a wild state, so the speaker believed that the half-wild races of white cattle in Chillingham Park, and a few other preserves in Britain, were descended from introduced domesti- cated cattle. The size of the dew-lap, and an occasional rudiment of the hump in these white cattle, as well as the approximation to the light grey colour characteristic of the Brahminy race, seemed to point to their primitive oriental source. But the speaker could not regard the pure \Vhite colour as natural to a primitive wild stock of oxen. It is now maintained by careful destruction of all piebald calves that are produced by the so-preserved half-wild breeds. 260 Prof, Owen^ on the Aboriginal Cattle of Britain. [May 2, If the blood of any of the aboriginal cattle, contemporary with the mammoth and hairy rhinoceros, still flowed in the veins of any of our domesticated races, he thought it would be that of the Bos longifrons transmitted through the short-horned or hornless varieties of the oxen of the mountains of Wales and Scotland. In conclusion the speaker referred to the subjoined table of the classification of recent and extinct hoofed quadrupeds, as indicative of the progressive extinction of those forms of Ungulata least likely to be of use to man, and of the substitution of the ruminant forms, which, from the perfect digestion of their food, elaborate from it the most sapid and nutritious kinds of flesh. UNGULATA. Typica. Artiodactyla* Anoplotherium Chalicotherium Dichobune Cainotherium Poebrotherium Xiphodon MoschusX Antilope Ovis Bos Cervus Camelopardalis Camelus Auchenia Merycotherium Merycopotamus Hippopotamus Dichodon Hyracotherium Hyopotamus Anthracotherium Hippohyus Choeropotamus Dicotyles Phacochoerus Sus. Perissodactyla f Palseotherium Paloplotherium Lophiodon Coryphodon Tapirus\ Macrauchenia Hippotherium Elasmotherium Hyrax Rhinoceros Acerotherium. * "KpTtos, jx^r; Saiicrukos, digitus. ■j" HspKro'oSdKruXos, qui digitos habet impares numero. X Only those genera printed in italics now exist. 1856.] General Monthly Meetiiig, 261 Aberrantia. TOXODONTIA Toxodon Nesodon. Proboscidia Elephas Mastodon Dinotherium. SiRENIA Manatus Halicore Rytina Halitherium Prorastomus. [R. 0.] GENERAL MONTHLY MEETING, Monday, May 5. William Pole, Esq. M.A. F.R.S. Treasurer and Vice-President, in the Chair. C. W. Dilke, Esq. C. Wentworth Dilke, Esq. and George Hudswell Westerman, Esq. were duly elected Members of the Royal Institution. The following Professors were unanimously re-elected : — William Thomas Brande, Esq. D.C.L. F.R.S. L. & E., as Honorary Professor of Chemistry in the Royal Institution. John Tyndall, Esq. Ph.D. F.R.S. as Professor of Natural Philosophy in the Royal Institution. A special vote of thanks was given to the Lord Stanley, M.P. M.R.I, for his present of a Magneto-Electric Machine, by Watkins and Hill. The following Presents were announced, and the thanks of the Members returned for the same : — From— Her Majesty's Government (hy Sir R. I. Murchison)— Memoirs of the Geo- logical Survey of the Unitea Kingdom : British Organic Remains, Decades V. &VIII. 4to. 1855-6. Administration of the Mines in Russia — Compte Eendu Annuel, pour 1854. Par A. T. KupflFer. 4to. 1855. Arnold, Thomas James, Esq. Life Sub. R.I. — The Law Amendment Journal, for April 1856. Astronomical Society, Roj^al — Monthly Notices. Vol. XVI. No. 6. 8vo. 1856. Author— The Great Arctic Mystery. 8vo. 1856. Bache, Dr. A. 1). {the Superintendant) — Annual Report of the United States Coast Survey, 1853. 4to. 262 General Monthly Meeting. [May 5, Bayley^ Francis, Esq. M.E.f.— The Book of Common Prayer, with Notes by Sir John Bay ley, Knt. 8vo. 1824. Memoirs of P. H. Bruce : a Military Officer in the Service of Prussia, Russia, and Great Britain ; containing his Travels in Germany, Russia, &c. 4to. 1782. Bell, Jacob, Esq. 3/.i?./.— Pharmaceutical Journal for May 1856. 8vo. Dooserj, Messrs. {the Publishers)— The Musical World for April 1856. 4to. BraSitr)/, Henri/, Esq. M.R. I.— The Ferns of Great Britain and Ireland. By T. Moore, F.L.S. Edited by J . Lindley, Pli.D. F.L.S. Part 13. fol. 1 856. British Architects, Boi/al Institute o/^— Proceedings in April 1856. 4to. British and Foreiyn Bible Societi/— The Bible in Chinese. 8vo. 1856. Calcutta Council of Education— Report on Public Instruction in the Lower Provinces of the Bengal Presidency, 1852-55. 8vo. Chemical Society— 3o\ima.\, No. 33. 8vo. 1856. Civil Engineers, Institute q/"— Proceedings in April 1856. 8vo. Editors — The Medical Circular for April 1856. 8vo. The Practical Mechanic's Journal for April 1 856. 4to. The Journal of Gas- Lighting for April 1856. 4to. The Mechanic's Magazine for April 1856. 8vo. The Athenseum for April 1856. 4to. The Engineer for April 1856. fol. Ethnological Society — Journal, Vol. IV. 8vo. 185G. Faraday, Professor, D.C.L. jFi^.S.— Monatsberichte derKonigl. Preuss. Aka- demie, Feb. 1856. 8vo. Berlin. Franklin Institute of Pennsylvania — Journal, Vol. XXXI. No. 4. 8vo. 1856. Graham, George, Esq. {Registrar- General) — Reports of the Registrar-General for April 1856. 8vo. 13th, 14th, 15th, and 16th Annual Reports, for 1850-3. 8vo, 1854-6. Halswell, Edmund S. Esq. — Reports of the Visitors of the County Lunatic Asylum at Colney Hatch, Middlesex. 12mo. 1852-6. Jackson, (Jharles T. M.D. — Congressional Report on the Ether Discovery. 8vo. 1852. Jmw, Wm. John, Esq. (the Author)— Reply to Mr. Ellis's Defence of his Theory on the Route of Hannibal. 8vo. 1856. Lewi7i, Malcolm, Esq. M.B.I. — Speech of the Earl of Albemarle on Torture in the Madras Presidency. 8vo. 1856. Mitchell, Mr. (the Publisher) — The Crusades: a Lecture, by Viscount Cran- borne. 8vo. 1856. Murray, Hon. Henry A. M.R.I, (the Author) — Lands of the Slave and the Free : or Cuba, the United States, and Canada. 2 vols. 16mo. 1855. I^ewton, Messrs. — London Journal (New Series), May 1856. 8vo. Novello, Mr. (the Publisher )— The Musical Times, for April 1856. 4to. Petermann, A. Esq. (the Author)— WiiiheWwa^en auf dem Gesammtgebiete der Geographic 1856: Heft 2. 4to. Gotha, 1856. Photographic S)ciety — Journal, No. 41. 8vo 1856. Pollock, W. Frederick, Esq M.R. I. —The Works of Abp.Grindal,Abp. Sandys, Bp. Pilkington, Bp. Ridley, Bp. Hooper, Archdeacon Philpot, R. Hutch- inson, and W. Fulke. (Published by the Parker Society.) 8 vols. 8vo. 1842-3. Prosser, John, Esq LifeSub. R.I. — Observations on a General Iron Railway, with Plates and Map. 8vo. 1823. Thirteen Letters from Sir I. Newton to John Covel, D.D- 8vo. 1848. The Suppressed Letter to G. Canning. 8vo. 1818. Quinton, J. R. Esq. {the Author) — Painless Tooth Extraction by Congelation. 16mo. 1856. Rcdpath, Leoj.'old, Fsq. J/./'./.— Paradise Lost. A Poem, in Ten Books. The Author, John Milton. London, Printed by S. Simmons. 4to. 1669. Royal Society of London — Proceedings. No. 20. 8vo. 1856. Society of Arts — Journal for April 185C. 8vo. 1856.] Mr. Bradbury on Security of Bank Notes. 263 South, Sir James, F.RS. M.R.I, {the Author)— Letter to the Fellows of the Koyal and Koyal Astronomical Societies. 8vo. 1856. University College , London — Annual Report, 1856. 8vo. Vereins zur Bef&rderung des Gewerbfleisses in Preussen — Verhandlungen, Jan. und Feb. 1856. 4to. Vincent, B. Asst.-Sec. E.I. — Dr. H. Winter, Litergeschichte der Deutschen Sprach Dicbt und Rede-Kunst. 8vo. Leipzig, 1 829. Dr. J. W. Schufer, Grundriss der Geschichte der Deutschen Literatur. 8vo. Bremen, 1850. Webster, J., M.D. F.R.S. 3f.i2./.— Reports of Bridewell and Bcthlem Hos- pitals, &c. 8vo. 1855. Williams, Thomas, M.D. {the Author) — On the Mechanism of Aquatic Respira- tion, and on the Structure of the Organs of Breathing in Invertebrate Animals. 8vo. 1853. Yorkshire Philosophical Socic/y— Proceedings. Vol. I. 8vo. 1855. Stanleii, The Lord, M.P. M.R.I.—A Magneto-Electric Machine, by Watkins aiid Hill. Pearsall, Mr. T. — Cast of a Shell in Limestone, from Malton, Yorkshire. WEEKLY EVENING MEETING, Friday, May 9. The Duke of Northumberland, K.G. F.R.S. President, in the Chair. Henry Bradbury, Esq. M.R.I. On the Security and Manufacture of Bank Notes. The many processes connected with the manufacture of Bank Notes invest the subject with deeper interest " than the mere importance attached to them as symbols of commercial confidence. To enter into the consideration of these processes would require a lengthened work. The object is rather to direct attention to tho consideration of that which is the most important feature in their manufacture, namely the engraving, because upon it their security in the eyes of the public mainly depends. It may perhaps be asked, — What occasion is there for discussing this question ? It is replied : that forgery is on the increase ; that difference of opinion exists as to the soundest method to be employed for obviating it ; that facilities are growing up to assist forgery ; and that, further, there is a tendency to employ that method which, in reality, is most exposed to the operations of the forger. If, indeed. .264 Mr. Henry Bradbury [May 9, we could be sure that the advance of genuine Art must ever distance that of the spurious — if the success of the forger were to stand in an inverse ratio to the genius of the artist — and if we were to ignore the wonderful skill and ability of the so-called uneducated classes — then indeed this subject would lose a considerable portion of its interest, and its technicality would be deprived of its moral importance. Had, however, the Report of the Committee * (though sitting upon this question so far back as 1819) been acted upon, it appears that this state of things could never have arisen ; for they arrived at those sound conclusions which are perfectly applicable at the present day. This Committee was organised in consequence of the rapid increase of convictions for the circulation of Bank of England Note forgeries. Juries began at last to feel a reluctance to visit with capital punishment a crime, for the prevention of which no proper precautions seemed to have been taken. The fact, also, that forged notes had passed undetected the scrutiny of the Bank Inspectors — determined the Council of the Society of Arts to take this step. The point for their especial consideration was to determine the means within the compass of Art, not so much totally to prevent the forgery of Bank of England Notes, (for that was obviously impossible,) as to elicit means of detection by increasing difficulty of imitation. This Report was one of great value, and is in these days still fiirther capable of extension, with the aid of a nice judgment, joined to artistic advantages which can now be commanded, to obviate many of the difficulties which originally beset this subject. The main feature, then, of the note, the Engraving, and its security, has been proved in practice as well as deposed to by artists of eminence, to depend upon the Vignette. The higher the quality of the artistic impress, therefore, which the vignette carries — the purer and severer the tone conferred upon its execu> tion— the greater the security of the note. This artistic impress might be still further extended to the whole face of the production. The great value of the vignette consists in this, that it is the uncounterfeitable seal of the note; — uncounterfeitable — because, though it may be imitated, its individuality cannot. This is illustrated by comparison with a picture ; it always conveys the style of the artist : his composition is known — his colour— his chiaroscuro — which the component parts of all works of Art have— a special individuahty, not to be obhterated from memory and which no copy can possess. However similar, there is a difference in the human countenance ; — however similar, there is a difference in handwriting. If then any * Report of the CommittcQ of the Society of Arts, on the Mode of Pre- venting the Forgery of Bank Notes, &c. London, 1819. 1856.] on the Security and Manufacture of Bank Notes. 265 number of the most eminent engravers were to endeavour to copy each other, — there would be sufficient evidence on casual examination to detect it. In a rivalship between them they might produce a work of similar beauty and general effect, but the difference of manner would be obvious to the commonest observer, and not only would the forgery be discovered, but the hand that had executed it would be identified. The eye of the Banking clerk, or the man of business, would soon become expert at this kind of Fine- Art reading. This was proved in the case of the Plymouth Bank half a century ago; their bills were forged, — their notes were not, simply on account of the vignette. When the vignette was added to the bills, the forgeries ceased. Of the various methods of engraving, the choice more especially lies between that of intaglio and surface-engraving j between steel and copper-plate, or letter-press and wood-engraving ; of the two, the first ranks pre-eminent, both for its beauty and adaptability to the production of Bank Notes. Years ago, objections might have been validly urged against this method. When the cost consequent upon the engraving of plates as they wore out counterbalanced the advantages gained, and moreover, the often changing the indi- viduality expressed upon the production, negatived its highest quaUty, the plan presented obstacles not easily surmounted in extensive practice ; but now Science enables us to overcome the impediment, and the Electrotype gives from one original an infinity of reproduction, with Httle more than nominal outlay. With regard to letter-press or surface-engraving, its power is too Umited in its effects to realise a high standard of artistic finish; while even cheapness, combined with rapidity of production, is not sufficient to counterbalance the absence of that continuous and unalterable individuality which should be sought for as the distin- guishing feature of the Bank Note. In stating this opinion, weight of contrary evidence has to be contended against, inasmuch as the Notes of the Bank of England, as also those of the Bank of France, Bank of Belgium, and Bank of Russia, are printed from surface- engraved plates : for the reasons assigned, such evidence cannot comitervail the immeasurable superiority of intaglio engraving for the main object desired, — namely, security. There is, however, one application — and that of considerable magnitude — to which this mode of printing has become of late more immediately applicable. It is used in the case of receipt-stamps in this country, and in that of postage-stamps in France. The main proposition on this subject is, that the union of Art, in which this country has been deficient, with Manufacture in which she is unrivalled (the vision of which is dawning in the distance), would place England in advance of every other nation. In the engraving of the Bank Note two principles are involved 266 Mr, Henry Bradbury [May 9, for consideration: first, the simplicity of its design, the purity of which is the gauge of its perfection; secondly, the combination of vignette-work with intricate engine-work: both these principles possess high claims to the attention of Banking authorities as security against forgery — the one on account of the difficulty of mechanical imitation — the other on the principle of the certainty of a first-sight recognition. Simplicity of design, when it amounts to the character of high-class Art, is much the best with regard to the issue of National Notes. Anything which addresses the mind is more clearly distinguishable than that which addresses the eye — and where variety of pattern and freaks of ornament distract the attention, it is put more within the field of the imitator than when he has to contend with an ideality — for which neither his education nor his pursuits are likely to fit him. By way of illustrating this principle an imaginary Note of the Bank of England is here submitted, because that establishment stands proudly and preeminently at the head of the- monetary transactions of the whole world, and because its Notes are more familiar. The Note is as simple as a National Note can safely be. * Its attributes are individual unity, if not beauty; simple and salient features, with due prominency of numerical value. The general character has a sort of medieval cast — it has been chosen, partly because it is totally different from the cursive style in common use, and is also in accordance with the revival of that style in the present day. The national characteristics are boldly expressed and displayed: attempt has been made to extend the artistic ideality of the Vignette — which is emblematic of the Nation — to the whole production. Breadth of design and unity of purpose have been sought for. Care has been taken in the introduction of the ornamentation, that it should not assume a position so prominent as to weaken the artistic effect, but rather serve as an auxiliary to Art. An additional and novel feature is thus conferred upon the writing, and all the points (and this should be borne in mind) subserving their particular purposes, contribute to the general harmony of the whole. Objections may be raised, that it is too architecturally bold — too florid in display — but it appears self-evident, that the nobler the character of a Note, the less it would enter into the comprehension of the forger — and even if some were not sensible of the difference between a fine original and a bad copy, that is no reason why others of better judgment should be precluded. The Bank of England Note has always been characterised by simplicity, but carried to an extreme in the opposite direction, the same general design having been preserved from the issue of their first note. The objection is, that its simplicity is too simple, — not bearing upon the face of it those features which characterise the ■^ -^ •?"^.,-v 1856.] on the Security and Manufacture of Bank Notes, 267 true Art-point. The vignette is a specimen the reverse of that which has been advocated; it is alike deficient in conception and execution. Surface-printing having been chosen as the medium, the Bank authorities were restricted in the apphcation of their Art. The great aim of the Bank has been to secure simple identity and ready recognition through the excellence of the paper, known by its peculiar colour, by its thinness and transparency, as well as by its feel, crisp and tough, patent to the sense of touch alone. The basis of its security to the public rests upon its paper. It is supposed to be unmatchable. As successful imitations of this paper, however, have been made abroad, and passed in this country, too much reliance ought not to be placed upon this superiority of the paper. Again, the fallacy of its security consists in the extreme facility it aifords for reproduction by hand, apart from reproduction afforded either by the Anastatic or Photographic processes. From 1837 to 1854, these notes were printed from steel plates, reproduced by the Siderographic or Transfer process; at the commencement of 1855, a change took place in the production of the notes by the substitution of surface- printing from electrotypes for steel-plate printing. A variation was then made in the form of the old note, by adopting an engraved signature instead of a manual one — the object being still further to strengthen the identity of recognition. The note of the Bank of France for ] 00 francs is a fair specimen of surface-printing : but its inferiority of design indicates that it has been adapted to its limited capabilities, and in this case is liable to those objections which are assignable to our own. The note however for 1000 francs is less exposed to the objections raised against the note for 100 francs, the difficulties of copying by hand being very great. These notes are printed upon both sides at the same time, effected by pulling an impression on the tympan itself before pulling each impression of the note : the reason for so doing is, that when the impression is pulled upon the face of the note, the paper receives two impressions at the same time, — the one, on the face of the note from the printing plate, — the other, on the reverse of the note, transferred from each impression on the tympan pulled previous to the genuine impression. The two impressions must necessarily register. This course has been pursued with the idea that perfect register of the two printings is a good gauge for detecting imitations. There is some reason in this, as it is a most difficult and tedious operation, requiring consummate skill on the part of the workman. It is said that not more than three hundred impressions are printed daily at one press — this does not speak much for economical production. Simplicity of design, however, is not to be advocated as solely applicable to a note in all instances. It is more especially suited for national notes, because immediate recognition should be one of their essential features ; but for provincial or local notes, not having 268 Mr. Henry Bradbury [May 9, so wide a commercial circulating range, the complex note has peculiar advantages ; the display of national emblems — ideal impress — and intuitive recognition being here unnecessary ; one merit in particular which it possesses, is that it is more available to represent small amounts, and for circulation among the humbler classes ; for an obvious reason, — the repetition of the amount represented, affording to the holder a more continued appreciation of its value. Art being the principle of a simple note ; Mechanics, or engraving by machinery, is that of a complex. This is performed in two ways ; relief and medallion-work, guilloche or rose-engine-work. The one represents models on flat surfaces : the other, lines, straight, waved or curved, circles, ellipses, parallel or intersecting, resulting in a particular effect. Different results are sought in the combi- nations produced from such machines : some prefer figures to appear white on black ; others prefer the reverse, the natural one, black on white. The latter is free from the confusion presented in the former ; its effect is more beautiful, and affords a much greater degree of detection. In the instruments used for the execution of these designs, (being the laboriously-perfected construction of F. J. Wagner, K.-H. Mechanicus, of Berlin), the adjustment admits such variety, that even allowing the forger to be possessed of a similar instrument, the chances against hitting on the several requisites to produce any particular pattern are infinite. It may admit of a doubt, whether their very intricacy, and the want of any prominent part to impress the attention, would not allow even a general resemblance to pass in the hurry of business. It is possible, however, to combine even within this intricacy of pattern and ornament an idea of that simplicity and singleness of recognition above mentioned. This Note, for'consecutiveness of argument, is also dignified with the name of the Bank of England. Even in this. Art may be made to hold an important place ; for idea in design can be seen in its impress, and thus almost the same, if not greater, from its mechanical construction, amount of security may be guaranteed, previously stated to have been the object of simplicity. It possesses unity of parts and purposes in design which tell much against the imitator. It is organised, as combining beauty with a business appearance. This small and convenient note can be divided into four parts for postal security. Its principle is essentially the same as that in the simple note — having its own individuality. Too much ornamentation is apt to bewilder, nay, misguide — too little is apt to abuse : but a proper combination of a certain amount of elaborate mechanical work, properly balanced to meet the effect of the design, will also combine beauty with security, with hardly less facility of recognition. The feasibility of this has been lost sight of — in fact, it was not formerly attainable — nor was it practicable until the Electrotype 1856.] on the Security and Manufacture of Bank Notes. 269 became a recognised agent in practical reproduction. By this power, surfaces of any given dimensions can be multiplied without reference to the quantity or delicacy of the work : not so by the mode of reproduction known as the Siderographic process for transferring objects engraved on steel to steel. This latter is certainly capable of reproducing to infinity, but with this important difference, that the smaller the subject the greater success in the transfer. While the fact of requiring retouching is an additional objection not at all applying to the Electrotype. It will be thus understood that so long as a process of reproduction was adhered to, only capable of transferring small subjects or fragments of designs, and in every case requiring to be retouched by the graver, so long must such kind of note be built up as it were piece by piece, and thereby perpetuate the barrier between the Art-ideal and the Art-mechanical. Since the discovery of the Electrotype, efforts have been made in several cases to apply its perpetuating power to the reproduction of copper engravings generally, — with no better result, however, in every case than signal failure. The average number of impressions from one plate rarely reached 500 — the electro-copper, too, spread from the pressure of the printing-press — and, in addition, from its softness, even curled round the cylinders. Too little attention was paid to the science of electro-deposition ; and failure arose from a want of confidence in its power, and want of energy in investi- gation. At the present time, partly owing to the perfection at which the process has arrived, and partly owing to an additional new agency brought into co-operation, an experiment was made a few months ago, under every possible disadvantage, to re-establish in this country (for it has long been in successful operation at Vienna) its practical, as well as its economical, adaptabiHty. This experiment was made upon the Bank Note of the National Bank of Brazil amounting to 1,200,000 notes, of very elaborate work, which have been printed from Electrotype plates : at the completion of this work, the means for future production existed for printing as many million notes more as thousands have already been printed — and, with this certainty, that the last note printed shall be identical with the first. The electro-plates in this instance, partly owing to the increased hardness in the copper deposited, and partly owing to a particular method of treatment, have yielded on an average 1600 perfect impressions — and experiments are in course of opera- tion for increasing this to between 3000 and 4000. The estabHsh- ment of this fact renders it almost imperative that greater attention should be given to the character of a note. If at the time that Art was more or less in its infancy, every endeavour was made to elevate the character of the Bank Note, and reports of scientific and practical men were sought for, and their suggestions attended to ; d fortiori, now that Science has done so much, and is capable of 270 Mr, Henry Bradbury [May 9, doing more, the Art-question of this suhject ought to hold an important place in its consideration. The peculiar advantage of the Electro over the Siderographic process will be apparent, seeing that the Electro copies the whole surface— and furthermore, it copies the exact state of the plates, without requiring the aid of scraper or burnisher, or that careful retouching and deepening of lines so indispensable to the success of Siderography. The term Siderographic has been made use of in connection with Bank Note printing. This is a process for transferring figures from steel to steel, and thus multiplying the number of plates to be printed from. It is one of exceeding simplicity ; but, as in most cases of the kind, however simple it may appear, it requires more than ordinary skill to effect successfully that little of which it is capable. It consists in taking up an engraved plate upon a roller of softened steel, a combination of rolling and pressure. The engraved subject thus stands in relief upon the roller. Identical plates are thus said to he produced. The objections are threefold, — First, every subject so transferred must be subsequently retouched by the graver. Secondly, its transferring properties are limited to very small subjects. Thirdly, and as a consequence, it is inapplicable to the manufacture of complex notes. Siderography has been in use for thirty years or more in America ; in fact, it was the invention of an American : but the Notes of the United States Government are not, and never have been — beautiful as their execution is — carried out after the principles advocated abdve. Referring to the American Notes, it is a curious fact that America being divided into so many States, and each State being represented by a different note, forgers did not think it worth their while to imitate, and therefore concocted notes of their own. It may prove interesting to supply some information concerning the Bank Notes of other countries. They carry on the face of them the absence of all those qualities which have been insisted upon, and actually in many instances appear to offer a premium to forgery. The aim would appear to have been to make them as ugly as possible, without affording them any counterbalancing security. Individual figures may be well executed — mechanical workmanship may also seem to be well done — but they are utterly destitute of leading ideas and harmonious properties — the true attributes of a Note. The Notes of the United States present engraved specimens of the highest order, but the subjects selected seem irrespective of their purpose, and the multiplicity of the figures distracts the attention. Again, there are the Austrian Notes. These fall con- siderably below the standard of American excellence. Vague in design, coarse in execution, the broken character of their design and the inconvenience of their shape render them unfitted for their purpose. Prussian Notes too partake of the same objections — 1856.] on the Security and Manufacture of Bank Notes. 271 preserving, in many instances, the appearance of fancy stationery. The Russian Notes might well be adopted for merchandise labels. To particularise the characteristics of all the different foreign notes would only become tedious, while placing them in the same category. If, however, the Notes of these States, betraying such defects, have in themselves upon the face of them an endeavour to f>er- petuate something of National Art, it must be plain that this country ought to be willing and able to effectuate a prototype of superiority. Great reliance for security is placed upon a combination of processes, and the greater the number employed in their con- struction,— the more different the effect resulting from each, — the more difficult it is supposed for the power of a single forger to em- brace the exercise of the whole. This, however, is a fallacious dependence, for the confusion created tends to less particularity of observance upon the part of the public. Thus much said upon the Manufacture of the Bank Note, the question of Security arises, a question most difficult of solution. For two reasons : on the one hand, because it is so generally admitted that what has been executed by one individual may be copied by another ; on the other, because it is not in the nature of things that a person who cannot read, should be protected from imposition by the most clumsy forgery. Another reason might be added, the general facility afforded by Science, not merely for the reproduction of one special object, but of almost everything. It is not logical to suppose that while Science helps the producer, she withholds her help from the imitator, and this point is the main one to be considered in the security of the Note. The first reason cannot be substantiated ; while the second is disposed of, on the grounds of the general spread of education. What is to be considered is, what is the nature of the so-called scientific facilities, and what are the steps to be adopted in the shape of counter-foils ; for while Science does help the imitator, she also comes again to the aid of the producer. It might be questioned whether any person coming forward to explain how many reproductive processes existed, and to what extent they could be carried, was exercising a privilege consistent with discretion. Such a method of proceeding, though new, is certainly capable of more good than evil ; for the more light there is thrown upon the subject, and the more imitators perceive and understand that the eye of genuine Science is upon them, the more fearful they will be of venturing on spurious manufacture that will certainly eventually be detected. The Anastatic process has been on several occasions brought prominently forward, with such promises, that its powers appeared of a dangerous character, competent to effect an unprincipled object. It professes that copper-plate and other engraving, old or new, ancient or fresh, can be transferred to plates of metal, and reprinted as fac-similes without re-engraving. In such a manner it Vol. II. T 272 Mr. Henry Bradbury [May 9, is supposed to be able to copy Bank Notes. Tbe process certainly has great claims to utility, if confined to its legitimate sphere ; for instance, when within the short space of ten days, 200 sets of fac-similes of the great Austrian Map of Russia and Turkey, for the use of the generals and officers of our armies in the East, were reproduced from 21 original copper-plate engravings, printed in "Vienna in 1829. The difference however between the nature of the engraving that characterises a map, and that which characterises (or which ought to characterise) a Bank Note, should be considered. The work in the one (the Note), whether it be complex or simple, ought to be sharp and clear, whereas in the case of the Map (and especially in the use for which it was required in the instance specified) it mattered little whether the lines transferred possessed great nicety of sharpness or not. The operation of effecting a transfer requires immense pressure, producing a flattening or spread- ing of the lines. In copper-plate printing, the ink lies upon the surface of the paper, not a transparent film as in surface-printing, but as a body ; the body naturally having a greater tendency to spread, the film a less. Therefore the best and simplest way to meet the supposed danger of the Anastatic is to adopt copper- plate and very fine work — as surface-printing with open-work only favours the transfer. If the Anastatic process thus lays claim to the ingenuity of an exhausted art, Photography appears as an infant science. When Photography made its first appearance, experiments were insti- tuted in order to ascertain how far it might be made subservient to forgery. Copies of Bank Notes were certainly produced by one or other of the branches of this art — but not to an extent to be considered dangerous. The copies were imperfect — there was a loss of sharpness ; an absence of reality ; a want of printed effect. The colour, too, instead of being black as in printing, was a sort of brown sepia. Another failure was in the representation of the water-mark, which appeared indeed as if it were really existing, but it was found impossible to give the peculiar effect of the water-mark produced by reflection and transmission. Up to this point then there was little to fear. Since that time Photography has made great advances ; and there exists a process which is capable of producing a more serious result than that previously obtained ; namely, a printing-plate. In cases where the engraving on a Note by reason of coarseness of character (such being exemplified more in letter-press than in copper-plate) is exposed to the reproductive powers of the Anastatic or the Photographic processes, and such mode of engraving (viz., the letter-press) must be from economical or other motives followed, then the antidote (at least, that in common use) consists in the adoption of printing in different colours. For instance : — Suppose some words or design elaborately engraved to be first printed in red on 1856.] on the Security and Manufacture of Bank Notes. 27^ the white paper ; and then the Note itself to be printed over this iu black — we should have a mixture of black print over red. In attempting to take an Anastatic or Photographic copy of this compound note, we shall have one printing-plate as the result : that is to say, that which was printed first in red, and that which was printed afterwards in black upon that red, is produced intermixed upon one plate, and whatever printing colour you apply to that plate for the purpose of producing an impression, you have the result of the two impressions in one colour ; and the point, wherein lies the difficulty, is that the separation of the two printings first referred to, in diiferent colours, cannot be effected without destroying the combined transfer. The more elaborate and artistic the second working in colour is rendered, the more the difficulty of dissection is increased. Again, another reason for employing artistic and elaborate work, is to thwart the efforts of the forger, supposing him to make use of the transfer for the purpose of engraving by hand, instead of using the chemical transfer. Also : if instead of taking those colours that are copyable by the agency of Hght, colours are selected that are not copyable, we shall have a result, which, though not precisely the same, presents difficulties equally insu- perable ; provided the work be of that character which is produced by the rose-engine-work : for, if these colours are not copyable by this agency, and those colours represent work which cannot be copied on the score of mechanical imitation, the forger stands in the same difficult predicament as before. To these points the attention of Banking authorities has been already awakened, as the adoption of it, in whole or in part, has become a prominent feature in commercial securities. With regard to these processes, admitting that they are, as they really are, — the latter especially, — dangerous where the execution is indifferent in character ; or, on the other hand, that they are not, or that they are merely put forward to subserve a business purpose, — in either case they should not be disregarded. If no notice be taken of them by bankers, if forgers perceive that increased facilities for copying are not met by increased efforts to defeat them, such indifference only gives encouragement for cultivating forgery as a science. Casual mention only has been made of the water-mark, not regarding it as unimportant, but secondary to the main consideration ; for a successful copy of a good engraving upon a spurious water- mark is more likely to impose upon the ignorant, than an inferior engraving upon the genuine water-mark. If then the water-mark were backed by the excellence of Art and engraving, it might safely be asserted that the Bank Note was unforgcable. But it may be said, the paper thus alone furnishes an absolute security, why make so great a parade of Art, design, engraving, &c., in its manufacture? — Because, whatever internal security exists in the paper, tends rather 274 Dr. Hofmann on [May 16, to the security of the Bank. — There should also he a prima facie security for the Public ; and if both are applied, they re-act upon each other, and the Note is perfect. Some foreign Banks adopt the plan of having different coloured papers for the notes of different denominations of value ; how far this is an advisable plan admits of question, for in addition to the fading of colour, the circumstance of receiving a piece of coloured paper is apt to induce a false security, assuming without inspection that the document is of a certain supposed value. Having shown that production and reproduction react upon each other, the question is, according to what plan the Bank Note should be manufactured ? Let Art be impressed on the Note. — Let ingenuity of design, executed by a hand whose genius would at once indicate its authority, be adopted so far as is consistent with a commercial purpose. — Let that mode of printing be employed which alone can render the delicacy and force of an Art-subject. If this course be followed, the greatest possible amount of difficulty would be placed in the way of reproduction by hand; the two scientific processes referred to cannot be brought to bear against it — and further, which should be another grand object, this Art-education of the people would eventually teach them prudence in distinguishing the genuine from the false. Lastly, if this should eventually be found insufficient to secure the desired result of unforgeability, then it should be imperative on the Government to resolve this question, and offer a reward, as has been done in other great public questions, for its solution. [H. B.] WEEKLY EVENING MEETING, Friday, May 16. SiE Charles Fellows, Vice-President, in the Chair. Dr. a. W. Hofmann, F.R.S. On the Chemical Type : Ammonia. The great laws which govern chemical combination, have been mostly recognized and elaborated by the study of mineral compounds, the examination of which at a very early period attracted the atten- 1856.] the Chemical Type : Ammonia. 276 tion of inquirers. It was only much later : — in fact, at a comparatively recent epoch, that the vegetable and the animal world were drawn into the circle of chemical observation. The progress made in the study of vegetable and animal substances was based, in the com- mencement at least, entirely and exclusively upon the knowledge which chemists possessed of mineral bodies. The experience, the ideas, gained in the examination of mineral substances, reflected themselves, if I may use this expression, in whatever views were brought forward regarding the nature of vegetable and animal compounds. Organic Chemistry was but a reproduction, in another form, of Mineral, or Inorganic Chemistry. This aspect, however, of the relative position of the two depart- ments of the science is rapidly changing. The amount of material accumulated by the indomitable perseverance of so many cultivators of Organic Chemistry, (a chaotic and almost inaccessible labyrinth, but a few years ago,j is rapidly assuming shape and order. The study of organic bodies has led to the observation of general laws, which could have never been discovered by the examination of mineral substances alone, but which begin to react in a most powerful manner upon our ideas regarding the constitution of these very mineral substances. The progress of our knowledge of organic bodies has opened new points of view, from which the con- stitution of mineral substances appears to us in a brighter light, in a simpler and more intelligible form. In one word. Organic Chemistry is beginning to repay, and I venture to say, with in- terest, the debt of gratitude which it owes to her elder sister, Mineral Chemistry. It is my task, this evening, to bring under your notice some especial examples in elucidation of the idea which I have endeavoured to delineate to you. Illustrations of this kind might be taken from widely different departments of the science. In consequence of special studies and predilections of my own, I have selected as material of illustration a class of substances of which the well-known compound Ammonia is the type. The four elements — Nitrogen, Phosphorus, Antimony, and Arsenic, although essentially differing in many of their physical properties, exhibit nevertheless an extraordinary similarity in their chemical character, and especially in their combining tendencies. With oxygen these four bodies produce teroxides and pentoxides which, in combination with water, have all decidedly acid proper- ties. Nitrous Acid . . . NO3 Nitric Acid . . . . NO5 Phosphorous Acid . PO3 Phosphoric Acid . . PO, Antimonious Acid . 8b03 Antimonic Acid . SbG» Arsenious Acid . . ASO3 Arsenic Acid , . . AsO, The latter acids, moreover, appear to be all tribasic ; in phos- 276 Dr. Hofmann on ' [May 16, phoric and arsenic acids the tribasic character is well marked ; with antinioiiic acid it is less pronounced ; and nitric acid is generally considered as a monobasic acid : but the progress of science will, I have no doubt, confirm our suspicion tiiat the nitrogen-acid is likewise of a tribasic character. The chlorides and bromides, cor- responding to the oxides of nitrogen, phosphorus, antimony, and arsenic, also exhibit, within certain limits, similar analogies.* Again, these four elements unite with hydrogen, and the com- pounds thus produced have a similar composition ; they are all terhydrides. Ammonia NIT3 Phosphoretted Hydrogen . . . PH3 Antimonetted Hydrogen . . . SbHg Arsenetted Hydrogen .... AsHg So far the analogy appears to be complete. Extraordinary dis- crepancies, however, are observed in the properties of these hydro- gen-compounds, for although they are all gases at the common temperature, although they all possess a marked odour, and are more or less inflammable, we find that ammonia is soluble in water, imparting a strongly alkaline character to this solution ; while the three other compounds, phosphoretted, antimonetted, and arsenetted hydrogens are insoluble in water, and without the slightest alkaline reaction. Again, ammonia when coming in contact with acids, absorbs these bodies with the greatest avidity, producing a series of well marked, mostly crystalline, compounds, which are called salts of ammonia, or ammoniacal salts, and of which sal ammoniac and sul- phate of ammonia are familiar illustrations. Antimonetted and arsenetted hydrogen, on the other hand, have never been combined with acids ; and in the case of phosphoretted hydrogen, only one salt-like compound, the hydriodate of phosphoretted hydrogen is known, which latter certainly presents considerable analogies with the salts of ammonia. Sulphate of Ammonia NH3, HSO4 Hydriodate of Ammonia NH3, HI Hydriodate of Phosphoretted Hydrogen . PH3, HI The want of similarity observed in the general characters of ammonia and the hydrogen-compounds of phosphorus, antimony, and arsenic, has always been an obstacle in the way of considering the four elements in question as members of the same natural family. f * For the purpose of illustration specimens of Nitrogen^ Phosphorus, Anfi- monyj and Arsenic, and of their oxides, chlorides, and bromides were upon the table. t The preparation and the principal properties of ammonia, phosphorcUed, aiUimonetled, and arsenetted hydrogen were experimentally exhibited. The 1856.] the Chemical Type: Ammonia. 277 The modern progress of Organic Chemistry has removed those difficulties. Organic Cliemistry deals with compound molecules, consisting of carbon and hydrogen, occasionally associated with nitrogen and oxygen. These compound molecules, often called compound radicals, simulate the deportment and exercise the functions of elementary substances. One of the most familiar illustrations of organic radicals is the radical Ethyl, consisting of four equivalents of carbon, and five of hydrogen, C4H5 = E, and which chemists assume to exist in alcohol and ether, the derivation of which from water becomes obvious by a glance at the following formulae : — Water .... {|{0 Alcohol . . . . \y\r\ Ether .... {|g Alcohol may be regarded as water, in which one equivalent of hydrogen is replaced by ethyl, ether, as water, for the two hydro- gen-equivalents of which ethyl has been substituted. The general characters of these three compounds greatly differ from one another; but some of the fundamental properties of water, ils neutral character for instance, are retained in the two substitution- products.* Recent researches have proved that in ammonia likewise the hydrogen-equivalents are replaceable by ethyl. Three new com- pounds are thus produced, which have received the names ethyla- manufacture of ammoniacal salts was, moreover, illustrated by a series of painted diagrams, and a set of large and beautiful specimens furnished by Messrs. Simp- son, Maule, and Nicholson, Kensington. Ammonia was evolved by the action of lime upon sal-ammoniac, phosphoretted hydrogen by that of hydrochloric acid upon phosphide of calcium, antimonetted and arsenetted hydrogen lastly, by introducing antimony- and arsenic-solutions into flasks from which hydrogen was l)eing evolved. Cylinders were filled with the four gases over mercury. The phosphoretted hydrogen evolved proved to be spontaneously inflammable. Antimonetted and arsenetted hydrogen were inflamed by a taper, and am- monia was shown to be capable of combustion by directing the current of the gas through a gas-flame. It was demonstrated that phosphoretted, antimonetted, and arsenetted hydrogens are not absorbed by water or even acids, and that they exhibit no alkaline reaction with vegetable colour's; whilst ammonia is absorbed by water and acids, and possesses the character of a strong alkali. * Specimens of water, alcohol, and ether placed in juxta-position. Ethyl- gas, obtained by the action of zinc upon the iodide of ethyl in a strong copper digestor, exhibited and burnt. '278 Dr. Hofmann on [May 16, mine, diet/it/ fa mine, and triethylamine : and the composition of which is illustrated by the following formulae : — (H Ammonia . N hi H Ethylamine . N IE Is IE Diethylamine . N E 1h (E Triethylamine . N ]e The three ethylated derivatives fully retain the fundamental character of ammonia ; they are powerful bases, capable of uniting with the acids, and of forming very definite, well-crystallizing salts. Owing to the diminution of volatility with the progress of ethyla- tion, the ethylated bases appear to be even more powerfully basic than the type itself. This development of basic power, as will be presently seen, deserves especial consideration. The substitution of ethyl for hydrogen presents no difficulty, it may be effected by several methods, one of the commonest processes consisting in the action of iodide of ethyl upon the body to be ethylated. Thus ammonia and iodide of ethyl produce ethylamine and hydriodic acid, which unite and give rise to the formation of hydriodate of ethylamine.* H E H + EI — N H H H Nm + EI = N H} HI, In consequence of the ethylated derivatives of ammonia retain- ing the basic character of the type, and exhibiting it, under certain conditions, even in a higher degree, the question naturally suggested itself, What would be the effect of introducing ethyl into phospho- retted, antimonetted, and arsenetted hydrogen ? The ethylation of these hydrogen-compounds presents difficulties not experienced with the nitrogen-series, and has been accomplished only by roundabout processes. Nor have all the terms, the exist- ♦ Ammonia, ethylamine, diethylamine, and triethylamine placed side by side ; the alkaline properties of these four substances experimentally demon- strated. Iodide of ethyl, and its action on ammonia exhibited. 1856. the Chemical Type: Ammonia, 279 ence of which theory suggests, as yet been obtained : compounds corresponding to ethylamine and to diethylamine are wanting at present, but the substances which correspond to triethylamine are known. The following table exhibits the compounds belonging to this group which are known. Nitrogen-Series, Ammonia Ethylamine Diethylamine . N Triethylamine . Nr, Playfair on Agrictdtural Experiments. 289 WEEKLY EVENING MEETING, Friday, May 30. Sib Roderick I. Murchison, G.C.S. F.R.S. Vice-President, in the Chair. Dr. Lyon Playfair, C.B. F.R.S. On the Chemical Principles involved in Agricultural Experiments, Dr. Playfair commenced by pointing out the modern views in regard to the food of plants. This may be divided into Air Food and Earth Food. The air food contains carbonic acid, water, ammonia, and nitric acid. Humus, to which great value was formerly attached by vegetable physiologists, is now known to act by its decay as an earth-provider of these substances. Although the soil and plants have the power of absorbing ammonia directly from the atmosphere, still the largest portion must be supplied to them in solution, either in the form of rain or dew. Our know- ledge on this subject is still imperfect. The average fall of rain on an acre may be taken in this country at 2270 tons. Taking the largest results for the ammonia found in rain water, only 30 lbs. of nitrogen would thus be supplied to crops, while a fair crop of cereals, growing in a few weeks only, contains 50 lbs. of nitrogen ; a crop of turnips contains 100 lbs., and one of mangold and clover, 1 50 lbs. No doubt nitric acid furnishes a considerable quantity of the nitrogen brought down by rain, but probably the dew is the more active agent, and this falls in proportion as diligence applied to the cultivation of land increases its radiating surface. With regard to the earth food, attention was drawn to the essential ingredients in all plants, and to the characteristic quantities of each in crops of different kinds. This was shown by curves, representing the abstracted ingredients of the soil in the usual crops. Within certain limits the air food may be viewed as of a con- stant composition and quantity, the diffusion of air equalising it over all districts. But the earth food is constantly varying, both in quality and quantity. Both air food and earth food being necessary conditions of fertility, the sterility or diminished fertility of a field must depend upon that condition of growth which is variable, and not upon that which is constant. The soil (the variable condition) 290 Dr, Playfair on the Chemical Principles [May 30, contains its ingredients either free or imprisoned, that is, either soluble or insoluble. The action of air, rain, and frost, liberates the imprisoned substances, rendering them available to plants. The mechanical operations of the farm, ploughing, harrowing, clod crushing, draining, &c., have this end in view. Jethro Tull ascrib- ed all success to such operations, and we find as long ago as the time of Cato, that the weathering effects on the soil were well known. But sooner or later the fertile ingredients of a soil must be removed by crops ; and to prevent sterility we supply, by manure, what we take away by cultivation. The primary action of manure must be to render to the soil that which is taken away ; or in other words, to produce a constant condition of growth in that which would otherwise be variable : but its secondary action often is, like humus, to supply an excess of air food in order to gain time in cultivation. Nutrition of plants must be directly proportional to the quantity of the necessary ingredients, and inversely proportional to the obstacles to their assimilation. The quantity of ingredients of earth food is constant for the same crop, within certain limits, arising from the greater or less development of particular organic substances in them. It is with plants as with animals. Formerly experiments used to be made with the latter by confining them to certain substances present in food. Dogs were fed separately on starch, or gelatine, or sugar, and they died, because all the conditions of nutrition were not satisfied. So it is with plants. If a single necessary ingredient be omitted, the plant cannot grow. A child could not be expected to thrive, if bone earth were carefully kept out of its food ; it might have flesh in abundance, enough to grow a little Hercules, or fat enough for a cherub, but without phosphate of lime it would refuse to grow. Exactly the same law rules vegetable growth. This, expressed as a law of fertility, means that the body in minima RULES the crop. If, for instance, bone earth be the body pre- sent in least quantity, and potash, soda, lime, &c. be present in excess, the extent of the crop will depend only upon the amount of bone earth, and the amounts of the other substances taken up will be exactly proportional to the limit of the former. All the bone earth being removed, the excess of the other substances is of no use, for the crop will refuse to grow. Add, however, an excess of bone earth, the crop will grow to the extent of the next substance, in minima, which may be sulphuric acid, or any other necessary ingredient. After explaining these general laws of fertility, the establish- ment of which are entirely due to Liebig, Dr. Playfair proceeded to apply them to the recent experiments made by farmers, and which were supposed by them to be irreconcileable with the pervail- ing notions of agricultural chemistry. He drew attention to the experiments of Mr. Lawes, who, aided by Dr. Gilbert, has carried on conscientiously, and with a full desire to arrive at just conclu- 1856.] invohedin Agricultural Experiments. 291 sions, a series of trials on a scale rather befitting a public body than a private individual. As a general result of these it was found that mineral manures alone did not suffice for full crops of cereals, but that ammonia was required to be added to them for proper success. The air then did not supply enough of the latter substance. As regards root crops, such as turnips, the result was different, mineral bodies, especially phosphates and sulphates, being found to be highly beneficial, while ammonia did not appear to be required as an addition ^to the manure. Alkalies were found favourable to the leguminous crops. When the different habits of the plants are considered, the results appear to be more comprehensible. Cereals have a small expanse of leaf, and a short period of life. In the 17 weeks of their growth at Rothamstead, they receive 800 or 900 tons of water as rain, of which about 500 tons are evaporated by passing through the crop. But in reality they make half their dry substance in four or five weeks, pjven admitting that they re- ceived all the ammonia of the rain, only about 12 lbs. of nitrogen would be thus received by the crops, instead of the 50 lbs. which they require. In the case of the short-lived cereals, to which a gain of time is everything, it would be natural to expect that an augmentation of ammonia would be favourable to their growth. The turnip, on the other hand, grows steadily over 21 weeks, making dry substance all the time, and with its broad leaves can take in more air food. Then, as regards earth food. The wheat has long greedy roots, which it throws out in all directions in search of food ; the turnip, with its small delicate fibres, is dependant on the food in its immediate vicinity. The wheat is an accomplished forager, like the light Zouave, and if food be in the soil it will pro- cure it. The turnip is like the bulky English soldier who, unless food is brought up to his tent door, is likely to fare badly. These habits of the plants determine why an artificial supply of an ingre- dient of air food is more necessary to one, and of earth food to the other ; but this result, though a valuable accession to our know- ledge, in no way shakes the original laws of nutrition. It is not, however, quite clear that even cereals with high cul- tivation may not get ammonia enough for themselves out of the air, without an artificial supply being given. At Lois Weedon, a soil frequently stirred and well worked has, without any manure, grown for ten years full crops of wheat of 34 bushels, on half an acre placed under growth, the other half being kept under fallow. In this instance, the absorption and radiating power of the soil being much increased by the frequent stirring, more anmionia is absorbed, and more dew containing ammonia is deposited, while the weathering of the soil has hitherto liberated sufficient mineral ingredients for full crops. If no other conclusion had been drawn by farmers from the Rothamstead experiments than that, in soils of an ordinary condition, an artificial supply of ammonia must be furnished to cereals, a 292 Dr. Play fair on Agricultural Experiments. [May 30, practical result of importance would have been arrived at ; but they have laid down as an agricultural dogma, that " nitrogen is the manure for wheat, and phosphorus and sulphates for turnip," thus re-introducing the notion of specifics into the laws of manure. "What, in the present stage of physiology, would be thought of a similar dogma in regard to animals? Because a horse contains more muscle, though less fat than a cow, it would not be permitted as a law of nutrition, to say that " Carbon is the food for a cow, and nitrogen for a horse ;" or because the sinewy Arab contains less bone earth than the large-boned Highlander, " Nitrogen is the food for an Arab, and phosphorus for a Highlander." This introduction of the idea of specifics into agriculture is dropping the veil of Isis over the whole subject. The sum of nutrition is made up of two factors, air food and earth food. Both factors are of equal importance. To discuss whether air food or earth food does most for particular crops is like discussing which side of a pair of scissors is most useful in cutting, or whether the upper or lower jaw is of most use in chewing. Dr. Playfair discussed at length the conditions of durable fertility of a soil, showing that the earth food was the capital of the farmer, and that any diminution in his capital should only be made by a deliberate and intelligent decision. For example, on a limestone soil it would be legitimate to draw upon lime without replacement, or in heavy clay soils upon alkalies. But as no soil is equally rich in all ingre- dients, an unintelligent draught on the soil will soon destroy it, for when one ingredient of earth food becomes in mbiimo the fertility is reduced to its proportion, and is destroyed when it is used up. Dr. Playfair then proceeded to show how the chief recent experiments in manures, which were rendered graphically in dia- grams, bore out these views. Among others a series of experiments made in Saxony to show the duration of the action of manures led to conclusive results. Thus, in one case, an addition of 11 lbs. of phosphoric acid produced an augmentation of a half more crop of clover containing 158 lbs. more of earth food and nitrogfen, thus showing, not that phosphoric acid was a specific, but that it was the body in minimo, and this being supplied, the crop was enabled to thrive and appropriate from the air and the soil the large quantities of other ingredients necessary for its development, but which were of no use when one ingredient was deficient in its necessary pro- portional quantity. All the variations of district or local agriculture, instead of representing specifics, which varying in them, would by contradictory experience destroy one another, represent only immediate require- ments of particular soils having different bodies in minimo. The only " specific " that should be admitted into farming is a knowledge of the laws upon which nutrition depends. As long as farming is carried on without an ac(iuaintance with these laws on the part of its cultivators, great progress cannot be expected, 1856.] General Mmithly Meeting, 293 and uncertain counsels will always prevail. It is not the duty of such philosophers as Liebig to make the direct applications of the laws of nature which they discover to the actual practice of the field. It is, however, the duty of the practical man thoroughly to understand these laws, and to find their technical applications for himself, for this is his art, as the other is the science of the philoso- pher. The recent review of the agricultural experiments which are supposed to be so antagonistic to Liebig's views of the science, Dr. Playfair had endeavoured to show were, when properly discus- sed, strongly confirmatory of them, and the antagonism was due not to any inherent contradiction between the philosopher and the farmer, but to a want of understanding as to their relative positions and duties to each other. [L.P.] GENERAL MONTHLY MEETING, Monday, June 2. William Pole, Esq. M.A. F.R.S. Treasurer and Vice-President, in the Chair. James C. C. Bell, Esq. Consul for the Grand Duchy of Tuscany. Charles Oliver Frederick Cator, Esq. William Crawford, Esq. Frederick William Irby, Esq. William Gibbs, Esq. John Smith, Esq. and Theodore Talbot, Esq. were duly elected Members of the Royal Institution. George Hudswell Westerman, Esq. was admitted a Member of the Royal Institution. The following Presents were announced, and the thanks of the Members returned for the same : — From Airey^ G. B. Esq. F.R.S. Astronomer-Royal— D'lscnssion of the Deviations of the Compass in Wood-built and Iron-built Ships. (Phil. Trans.) 4to. 1856. 294 General Monthly Meetimj. [Jane 2, A\lie&, T. W. E^. ALA. M.R.I, {the Author)— The See of St. Peter, the Rock of the C/hurch, the Source of Jurisdiction, aud the Centre of Unity. 16mo. 1855. Astronomical Society, Eoi/al— Monthly Notices. Vol. XVI. No. 7. 8vo. 1856. Memoirs, Vol. XXIV. 4to. 1856. Monthly Notices, Vol. XV. 8vo. 1854-5. Bell, Jacob, Esq. MM. I. — Pharmaceutical Journal for June, 1856. 8yo. Booseif, Messrs. (the Publishers) — The Musical World for May, 1856. 4to. Bradburi/, Henry, Esq. M.R.I, (the Author) — On the Security and Manufacture of Bank-Notes ; a Lecture. 4to. 1856. The Ferns of Great Britain and Ireland. By T. Moore, F.L.S. Edited by J. Lindley, Ph.D. F.L.S. Part 14. fol. 1856. British Architects, Royal Institute of — Proceedings in May 1856. 4to. British Museum, Trustees of the — List of Birds. Part 4. 12mo. 1856. List of Lepidopterous Insects. Part 7. 12mo. 1856. Civil Engineers, Institute of— Proceedings in May 1856. 8vo. Commissioners for the Exhibition of 1851 — Third Report. 8vo. 1856. Domville, Sir [V., Bart. M.R.I, {the Author) — The Sabbath : or an Inquiry into the Supposed Obligation of the Sabbaths of the Old Testament. 2 vols. 8vo. 1849-55. Dublin Society, Royal— Journal, Vol. I. Part 1. 8vo. 1856. Etst India Company, the Hon. — Magnetical and Meteorological Observations at Bombay in 1852. 4to. 1855. Editors— The Medical Circular for May 1856. 8vo. The Practical Mechanic's Journal for May 1856. 4to. The Journal of Gas- Lighting for May 1856. 4to. The Mechanic's Magazine for May 1856. 8vo. The Athenaeum for May 1856. 4to. The Engineer for May 1856. fol. The Literarium for May 1856. fol. Faraday, Professor, D.C.L. F.R.S. (the Author) — Experimental Researches in Electricity. Thirtieth Series. (Phil. Trans.) 4to. 1856. Monatsberichte der Kdnigl. Preuss. Akademie, Marz und April IS56. 8vo. Berlin. Geographical Society, Royal — Proceedings, Nos. 1 and 2. 8vo. 1855-6. Geological Society of Dublin '•~Jo\xma.l,Yo\. VII. Parts 1 and 2. 8vo. 1856. Geological Sbciefy— Journal, No. 46. 8vo. 1856. Graham, George, Esq. (Registrar- General) — Report of the Registrar-General for May 1856. 8vo. Grove, W.R. Esq. Q.C. F.R.S. M.R.I.(the Author)— Lecture on the Progress of Physical Science. 8vo. 1842. Knight, Mr. G. (the Publisher)— B,. F. Barnes on the Dry Collodion Process. 16mo. 1856. Lewin, Malcolm, Esq. M.R.I. — Address to the Citizens of London on the Pending Corporation Bill. 8vo. 1856. Linnean Society— ionmdiX, Vol. I. No. 2. 8vo. 1856. Londesborough, the Lord, K.H. M.R.I. — Miscellanea Graphica, No. 9. 4to. 1856. Macrory, Edmund, Esq. M.R.I, {the Editor) — The Private Diarie of Elizabeth Viscountess Mordaunt (from the M.S.) (Portraits.) Privately printed. 16mo. 1856. Newton, Messrs.— London Journal (New Series), June 1856. 8vo. Novella, Mr. {the Publisher) — The Musical Times for May 1856. 4to. Photographic Society — Journal, No. 42. Svo. 1856. Radcliffe Trustees, Ox/brd— Radcliffe Observations for 1854. Svo. 1856. Shariatt, Mr. Edwin {the Author) — Popular Treatise on Light. 16mo. 1856. Society of Arts. — Journal for May 1856. 8vo. Tyndall, Professor, F.R.S. {the Author) — Further Researches on the Polarity of the Diamagnetic Force. (Phil. Trans.) 4to. 1856. 1856.] Prof. Tyndall on Cleavage oj Crystals, 295 VVeale, John, Esq. (the Publisher) — Rudimentary Treatises : — Recent and Fossil Shells; Part 3. 12mo. 1856. Use of Field Artillery ; by Taubert. 12mo. 1856. Key to the Elements of Algebra. 12mo. 1856. Ships' Anchors. 12mo. 1856. WEEKLY EVENING MEETING, Friday, June 6. SiK Roderick I. Murchison, G.C.S. F.R.S. Vice-President, in the Chair. John Tyndall, Esq. F.R.S. PaCWESSOE OP NATURAL PHILOSOPHY IN THE BOYAL INSTITUTION. Comparative View of the Cleavage of Crystals and Slate Hocks. When the student of physical science has to investigate the character of any natural force, his first care must be to purify it from the mixture of other forces, and thus study its simple action. If, for example, he wishes to know how a mass of water would shape itself, supposing it to be at liberty to follow the bent of its own molecular forces, he must see that these forces have free and undisturbed exercise. We might perhaps refer him to the dew- drop for a solution of the question ; but here we have to do, not only with the action of the molecules of the liquid upon each other, but also with the action of gravity upon the mass, which pulls the drop downwards and elongates it. If he would examine the problem in its purity, he must do as Plateau has done, withdraw ^the liquid mass from the action of gravity, and he would then find the shape of the mass to be perfectly spherical. Natural processes come to us in a mixed manner, and to the uninstructed mind are a mass of unintelligible confusion. Suppose half-a-dozen of the best musical performers to be placed in the same room, each playing his own instrument to perfection : though each individual instrument migh be a wellspring of melody, still the mixture of all would produce mere noise. Thus it is with the processes of nature. In nature mechanical and molecular laws mingle and create apparent confusion. Their mixture constitutes what may be called the noise of natural laws ; and it is the vocation of the man of science to resolve this noise into its components, and thus to detect the " music " in which the foundations of nature are laid. The necessity of this detachment of one force from all other 296 ^rof' Tyndall, on the Comparative View of [June 6, forces is nowhere more strikingly exhibited than in the phaeno- mena of crystallization. I have here a solution of sulphate of soda. Prolonging the mental vision beyond the boundaries of sense, we see the atoms of that liquid, like squadrons under the eye of an experienced general, arranging themselves into battalions, gathering round a central standard, and forming themselves into solid masses, which after a time assume the visible shape of the crystal which I here hold in my hand. I may, like an ignorant meddler wishing to hasten matters, introduce confusion into this order. I do so by plunging this glass rod into the vessel ; the consequent action is not the pure expression of the crystalline forces ; the atoms rush together with the confusion of an unor- ganized mob, and not with the steady accuracy of a disciplined host. Here also in this mass of bismuth we have an example of this confused crystallization ; but in the crucible behind me a slower process is going on : here there is an architect at work " who makes no chips, no din," and who is now building the particles into crystals, similar in shape and structure to those beautiful masses which we see upon the table. By permitting alum to crystal- lize in this slow way, we obtain these perfect octahedrons ; by allowing carbonate of lime to crystallize, nature produces these beautiful rhomboids ; when silica crystallizes, we have formed these hexagonal prisms capped at the ends by pyramids ; by allowing saltpetre to crystallize we have these prismatic masses, and when carbon crystallizes, we have the diamond. If we wish to obtain a perfect crystal, we must allow the molecular forces free play ; if the crystallizing mass be permitted to rest upon a surface it will be flattened, and to prevent this a small crystal must be so suspended as to be surrounded on all sides by the liquid, or, if it rest upon the surface, it must be turned daily so as to present all its faces in succession to the working builder. In this way the scientific man nurses these children of his intel- lect, watches over them with a care worthy of imitation, keeps all influences away which might possibly invade the strict morality of crystalline laws, and finally sees them developed into forms of symmetry and beauty which richly reward the care bestowed upon them.* In building up crystals, these little atomic bricks often ar- range themselves into layers which are perfectly parallel to each other, and which can be separated by mechanical means ; this is called the cleavage of the crystal. I have here a crystallized mass which has thus fer escaped the abrading and disintegrating forces which sooner or later determine the fate of sugar-candy. If I am skilful enough I shall discover that this crystal of sugar cleaves * To Mr. Pattinson, of the Felling Chemical Works, Newcastle-upon- Tyne, I am indebted for some fine specimens of crystallized alum and car- bonate of soda. 1856.] the Cleavage of Crystals and Slate Rocks. 297 with peculiar facility in one direction. Here again I have a mass of rock-salt : I lay my knife upon it, and with a blow cleave it in this direction ; but I find on further examining this substance that it cleaves in more directions than one. Laying my knife at right angles to its former position, the crystal cleaves again ; and finally placing the knife at right angles to the two former positions, the mass cleaves again. Thus rock-salt cleaves in three direc- tions, and the resulting solid is this perfect cube, which may be broken up into any number of smaller cubes. Here is a mass of Iceland spar, which also cleaves in three directions, not at right angles, but oblique to each other, the resulting solid being a rhomboid. In each of these cases the mass cleaves with equal facility in all three directions. For the sake of completeness I may say that many substances cleave with unequal facility in different directions, and the heavy spar I hold in my hand presents an example of this kind of cleavage. Turn we now to the consideration of some other phaenomena to which the term cleavage may be applied. This piece of beech- wood cleaves with facility parallel to the fibre, and if our ex- periments were fine enough we should discover that the cleavage is most perfect when the edge of the axe is laid across the rings which mark the growth of the tree. The fibres of the wood lie side by side, and a comparatively small force is suflficient to separate them. If you look at this mass of hay severed from a rick, you will see a sort of cleavage developed in it also ; the stalks lie in parallel planes, and only a small force is required to separate them laterally. But we cannot regard the cleavage of the tree as the same in character as the cleavage of the hayrick. In the one case it is the atoms arranging themselves according to organic laws which produce a cleavable structure ; in the other case the easy separation in a certain direction is due to the me- chanical arrangement of the coarse sensible masses of the stalks of hay. In like manner I find that this piece of sandstone cleaves parallel to the planes of bedding. This rock was once a powder, more or less coarse, held in mechanical suspension by water. The powder was composed of two distinct parts, fine grains of sand and small plates of mica. Imagine a wide strand covered by a tide which holds such powder in suspension :* how will it sink ? The rounded grains of sand will reach the bottom first, the mica afterwards, and when the tide recedes, we have the little plates shining like spangles upon the surface of the sand. Each successive tide brings its charge of mixed powder, deposits its duplex layer day after day, and finally masses of immense thick- ♦ I merely use this as an illustration ; the deposition may have really been due to sediment carried down by rivers. But the action must have been periodic, and the powder duplex. 298 Prof. Tyndall, o/i the Comparative View of [Ju!ie 6, iiess are thus piled up, which by preserving the alternations of sand and mica tell the tale of their formation. I do not wish you to accept this without proof. Take the sand and mica, mix them together in water, and allow them to subside, they will arrange themselves in the manner I have indicated ; and by repeating the process you can actually build up a sandstone mass whicii shall be the exact counterpart of that presented by nature, as I have done in this glass jar. Now this structure cleaves with readiness along the planes in which the particles of mica are strewn. Here is a mass of such a rock sent to me from Halifax : here are other masses from the quarries of Over Darwen, in Lancashire.* With a hammer and chisel you see I can cleave them into flags ; in- deed these flags are made use of for roofing purposes in the dis- tricts from which the specimens have come, and receive the name of " slatestone." But you will discern without a word from me, that this cleavage is not a crystalline cleavage any more than that of a hayrick is. It is not an arrangement produced by molecular forces ; indeed it would be just as reasonable to suppose that on this jar of sand and mica the particles arranged themselves into layers by the forces of crystallization, instead of by the simple force of gravity, as to imagine that such a cleavage as this could be the product of crystallization. This, so far as I am aware of, has never been imagined ; and it has been agreed among geologists not to call such splitting as this cleavage at all, but to restrict the term to a class of phaenomena which I shall now proceed to consider. Those who have visited the slate quarries of Cumberland and North Wales will have witnessed the phaenomena to which I refer. We have long drawn our supply of roofing-slates from such quarries ; schoolboys ciphered on these slates, they were used for tombstones in churchyards, and for billiard-tables in the metropolis ; but not until a comparatively late period did men begin to inquire how their wonderful structure was produced. What is the agency which enables us to split Honister Crag, or the cliflTs of Snowdon, into laminae from crown to base ? This question is at the present moment one of the greatest difficulties of geologists, and occupies their attention perhaps more than any other. You may wonder at this. Looking into the quarry of Penrhyn, you may be disposed to explain the question, as I heard it explained two years ago. " These planes of cleavage," said a friend who stood beside me on the quarry's edge, "are the planes of stratification which have been lifted by some convulsion into an almost vertical position.'* But this was a great mistake, and indeed here lies the grand difficulty of the problem. These planes of cleavage stand in most cases at a high angle to the bedding. Thanks to Sir Roderick * For the specimens from Halifax I have to thank Mr. Richard Carter, and for those from Darwen I am indebted to Mr. J. Singteton. 1856.] the Cleavage of Crystals and Slate Rocks. 299 Murchison, who has kindly permitted me the use of specimens from the Museum of Practical Geology (and here I may be per- mitted to express my acknowledgments to the distinguished staff of that noble establishment, who, instead of considering me an in- truder, have welcomed me as a brother), I am able to place the proof of this before you. Here is a mass of slate in which the planes of bedding are distinctly marked ; here are the planes of cleavage, and you see that one of them makes a large angle with the other. The cleavage of slates is therefore not a question of stratification, and the problem which we have now to consider is, " By what cause has this cleavage been produced ? " In an able and elaborate essay on this subject in 1 835, Professor Sedgwick proposed the theory that cleavage is produced by the action of crystalline or polar forces after the mass has been con- solidated. " We may affirm," he says, *' that no retreat of the parts, no contraction of dimensions in passing to a solid state, can explain such phaenomena. They appear to me only resolvable on the supposition that crystalline or polar forces acted upon the whole mass simultaneously in one direction and with adequate force." And again, in another place : " Crystalline forces have rearranged whole mountain masses, producing a beautiful crystalline cleavage, passing alike through all the strata."* The utterance of such a man struck deep, as was natural, into the minds of geologists, and at the present day there are few who do not entertain this view either in whole or in part.f The magnificence of the theory, indeed, has, in some cases, caused speculation to run riot, and we have books published, aye and largely sold, on the action of polar forces and geologic magnetism, which rather astonish those who know some- thing about the subject. According to the theory referred to, miles and miles of the districts of North Wales and Cumberland, comprising huge mountain masses, are neither more nor less than the parts of a gigantic crystal. These masses of slate were originally fine mud ; this mud is composed of the broken and abraded particles of older rocks. It contains silica, alumina, iron, potash, soda, and mica mixed in sensible masses mechani- cally together. In the course of ages the mass became consoli- dated, and the theory before us assumes that afterwards a pro- cess of crystallization rearranged the particles and developed in * Transactions of the Geological Society, ser. ii. vol. iii. p. 477. t In a letter from Sir Charles Lyell, dated fr(»m the Cape of Good Hope, February 20, 1836, Sir John Herschel writes as follows :—" If rocks have been so heated as to allow of a commencement of crystallization, that is to say, if they have been heated to a point at which the particles can begin to move amongst themselves, or at least on their own axes, some general law must then determine the position in which these particles will rest on cooling. Probably that position will have some relation to the direction in which the heat escapes. Now when all or a majority of particles of the same nature have a general ten- dency to one position, that most of course determine a cleavage plane." 300 Prof, Tyndall, on the Comparative View of [June 6, the mass a single plane of crystalline cleavage. With reference to this hypothesis, I will only say that it is a bold stretch of analogies : but still it has done good service ; it has drawn attention to the question ; right or wrong a theory thus thoughtfully uttered has its value ; it is a dynamic power wliich operates against intellectual stagnation ; and even by provoking opposition is eventually of ser- vice to the cause of truth. It would however have been remarkable if, among the ranks of geologists themselves, men were not found to seek an explanation of the phaenomena in question, which involved a less hardy spring on the part of the speculative faculty than the view to which 1 have just referred. The first step in an inquiry of this kind is to put oneself into contact with nature, to seek facts. This has been done, and the labours of Sharpe (the late President of the Geological Society, who, to the loss of science and the sorrow of all who knew him, has so suddenly been taken away from us), Sorby, and others, have fur- nished us with a body of evidence which reveals to us certain important physical phaenomena, associated with the appearance of slaty cleavage, if they have not produced it : the nature of this evidence we will now proceed to consider. Fossil shells are found in these slate-rocks. I have here several specimens of such shells, occupying various positions with regard to the cleavage planes. They are squeezed, distorted, and crushed. In some cases a flattening of the convex shell occurs, in others the valves are pressed by a force which acted in the plane of their junction ; but in all cases the distortion is such as leads to the inference that the rock which contains these shells has been subjected to enormous pressure in a direction at right angles to the planes of cleavage ; the shells are all flattened and spread out upon these planes. I hold in my hand a fossil trilobite of normal proportions. Here is a series of fossils of the same creature which have suffered distortion. Some have lain across, some along, and some oblique to the cleavage of the slate in which they are found ; in all cases the nature of the distortion is such as required for its production a compressing force acting at right angles to the planes of cleavage. As the creatures lay in the mud in the manner in- dicated, the jaws of a gigantic vice appear to have closed upon them and squeezed them into the shape you see. As further evidence of the exertion of pressure, let me introduce to your notice a case of contortion which has been adduced by Mr. Sorby. The bedding of the rock shown in this figure was once horizontal ; at A we have a deep layer of mud, and at m w a layer of compara- tively unyielding gritty material ; below that again, at B, we have another layer of the fine mud of which slates are formed. This mass cleaves along the shading lines of the diagram : but look at the shape of the intermediate bed : it is contorted into a serpentine form, and leads irresistibly to the conclusion that the mass has been pressed together at right angles to the planes of 1856.] tJie Cleavage of Crystals and Slate Rocks. 301 experimentally imitated, and I which this is done and the same cleavage. This action can be have here a piece of clay in result produced on a small scale. The amount of compression, in- deed, might be roughly estimated by supposing this contorted bed mn to be stretched out, its length measured and compared with the distance cd; we find in this way that the yielding of the mass has been considerable. Let me now direct your at- tention to another proof of pres- sure ; you see the varying colours which indicate the bedding on this mass of slate. The dark portion, as I have stated, is gritty, and composed of comparatively coarse particles, which, owing to their size, shape and gravity, sink first and constitute the bottom of each layer. Gradually, from bottom to top the coarseness di- minishes, and near the upper sur- face of each layer we have a mass of comparatively fine clean mud. Sometimes this fine mud forms distinct layers in a mass of slate- rock, and it is the mud thus con- solidated from which are derived the German razor-stones, so much prized for the sharpening of sur- gical instruments. I have here an example of such a stone ; when a bed is thin, the clean white mud is permitted to rest, as in this case, upon a slab of the coarser slate in contact with it : when the bed is thick, it is cut into slices which are cemented to pieces of ordinary slate, and thus rendered stronger. The mud thus deposit- ed sometimes in layers is, as might be expected, often rolled up into nodular masses, carried forward, and deposited by the rivers from which the slate-mud has subsided. Here, indeed, are such nodules enclosed in sand-stone. Everybody who has ciphered upon a school-slate must remember the whitish-green spots which some- times dotted the surface of the slate ; he will remember how his slate-pencil usually slid over such spots as if they were greasy ; now these spots are composed of the finer mud, and they could not, on account of their fineness, bite the pencil like the surrounding gritty portions of the slate. Here is a beautiful example of the spots : you observe them on the cleavage surface in broad patches ; but if this mass has been compressed at right angles to the planes 302 Prof, Tyndall, on the Comparative View of [June 6, of cleavage, ought we to expect the same marks when we look at the edge of the slab ? The nodules will be flattened by such pres- sure, and we ought to see evidence of this flattening when we turn the slate edgeways. Here it is. The section of a nodule is a sharp ellipse with its major axis parallel to the cleavage. There are other examples of the same nature on the table ; I have made excursions to the quarries of Wales and Cumberland, and to many of the slate-yards of London, but the same fact invariably appears, and thus we elevate a common experience of our boyhood into evidence of the highest significance as regards one of the most important problems of geology. In examining the magnetism of these slates, I was led to infer that these spots would contain a less amount of iron than the surrounding dark slate. The analysis was made for me by Mr. Hambly, in the laboratory of Dr. Percy, at the School of Mines. The result which is stated in this Table, justifies the conclusion to which I have referred. Analysis of Slate. Purple Slate, two analyses. 1. Per-centage of iron . . . 5*85 2. „ „ ... 6-13 Mean . . 5*99 Greenish Slate. 1 . Per-centage of iron . . . 3 * 24 2. „ „ ... 3-12 Mean . . 3*18 The quantity of iron in the dark slate immediately adjacent to the greenish spot is, according to these analyses, nearly double of the quantity contained in the spot itself. This is about the proportion which the magnetic experiments suggested. Let me now remind you that the facts which I have brought before you are typical facts — each is the representative of a class. We have seen shells crushed ; the unhappy trilobites squeezed, beds contorted, nodules of greenish marl flattened ; and all these sources of independent testimony point to one and the same conclusion, namely, that slate-rocks have been subjected to enormous pressure in a direction at right angles to the planes of cleavage.* * While to my mind the evidence in proof of pressure seems perfectly irresistible, I by no means assert that the manner in which I have stated it is incapable of modification. All that I deem important is tlie fact that pressure has been exerted ; and provided this remain firm, the fate of any minor portion of the evidence by which it is here established is of- compara- tively little moment. 1856.] the Cleavage of Crystals and Slate llocks, 303 In reference to Mr. Sorby's contorted bed, I have said that by supposing it to be stretched out and its length measured, it would give us an idea of the amount of yielding of the mass above and below the bed. Such a measurement, however, would not quite give the amount of yielding ; and here I would beg your attention to a point, the significance of which has, so far as I am aware of, hitherto escaped attention. I hold in my hand a specimen of slate with its bedding marked upon it ; the lower portions of each bed are composed of a comparatively coarse gritty material something like what you may suppose this contorted bed to be composed of. Well, I find that the cleavage takes a bend in crossing these gritty portions, and that the tendency of these portions is to cleave more at right angles to the bedding. Look to this diagram : when the forces commenced to act, this intermediate bed, which though com- paratively unyielding is not entirely so, suffered longitudinal pres- sure ; as it bent, the pressure became gradually more lateral, and the direction of its cleavage is exactly such as you would infer from a force of this kind — it is neither quite across the bed, nor yet in the same direction as the cleavage of the slate above and below it, but intermediate between both. Supposing the cleavage to be at right angles to the pressure, this is the direction which it ought to take across these more unyielding strata. Thus we have established the concurrence of the phaenomena of cleavage and pressure — that they accompany each other ; but the question still remains. Is this pressure of itself sufficient to account for the cleavage ? A single geologist, as far as I am aware, answers boldly in the affirmative. This geologist is Sorby, who has attacked the question in the true spirit of a physical investi- gator. You remember the cleavage of the flags of Halifax and Over Darwen, which is caused by the interposition of plates of mica between the layers. Mr. Sorby examines the structure of slate-rock, and finds plates of mica to be a constituent. He asks himself, what will be the effect of pressure upon a mass containing such plates confusedly mixed up in it ? It will be, he argues, and he argues rightly, to place the plates with their flat surfaces more or less perpendicular to the direction in which the pressure is exerted. He takes scales of the oxide of iron, mixes them with a fine powder, and on squeezing the mass finds that the tendency of the scales is to set themselves at right angles to the line of pressure. Now the planes in which these plates arrange themselves will, he contends, be those along which the mass cleaves. I could show you by tests of a totally different character from those apj)lied by Mr. Sorby, how true his conclusion is, that tiie effect of pressure on elongated particles, or plates, will be such as he describes it. Nevertheless, while knowing this fact, and admi- ring the ability with which Mr. Sorby has treated this question, I cannot accept his explanation of slate- cleavage. I believe that Vol. IL x 304 PTfof. Tyndall, on the Comparative View of [June 6, even if these plates of mica were wholly absent the cleavage of slate rocks would be much the same as it is at present. I will not dwell here upon minor facts, — I will not urge that the perfection of the cleavage bears no relation to the quantity of mica present ; but I will come at once to a case which to my mind completely upsets the notion that such plates are a necessary element in the production of cleavage. Here is a mass of pure white wax : there are no mica particles here ; there are no scales of iron, or anything analogous mixed up with the mass. Here is the self-same substance submitted to pressure. I would invite the attention of the eminent geologists whom I see before me to the structure of this mass. No slate ever exhibited so clean a cleavage ; it splits into laminae of surpassing tenuity, and proves at a single stroke that pressure is sufficient to produce cleavage, and that this cleavage is independent of the intermixed plates of mica assumed in Mr. Sorby's theory. I have purposely mixed this wax with elongated particles, and am unable to say at the present moment that the cleavage is sensibly affected by their presence, — if anything, I should say they rather impair its fineness and clearness than promote it. The finer the slate the more perfect will be the resemblance of its -cleavage to that of the wax. Compare the surface of the wax with the surface of this slate from Borrodale in Cumberland. You have precisely the same features in both : you see flakes clinging to the surfaces of each, which have been partially torn away by the cleavage of the mass : I entertain the conviction that if any close observer compares these two effects, he will be led to the conclusion that they are the product of a common cause.* But you will ask me how, according to my view, does pressure produce this remarkable result ? This may be stated in a very few words. Nature is everywhere imperfect ! The eye is not perfectly achromatic, the colours of the rose and tulip are not pure colours, and the freshest air of our hills has a bit of poison in it. In like manner there is no such thing in nature as a body of perfectly •homogeneous structure. I break this clay which seems so inti- mately mixed, and find that the fracture presents to my eyes in- numerable surfaces along which it has given way, and it has yielded along these surfaces because in them the cohesion of the mass is less than elsewhere. I break this marble, and even this wax, and observe the same result : look at the mud at the bottom of a dried pond ; look to some of the ungravelled walks in Kensington Gar- * I have iisually softened the wax by wanning it, kneaded it with the fingers, and pressed it between thick plates of glass previously wetted. At the ordinary summer temperature the wax is soft, and tears rather than cleaves ; on this account I cool my compressed specimens in a mixture of pounded ice and salt, and when thus cooled they split beautifully. 1856.} the Cleavage of Crystals and Slate Rocks. 305 dens on drying after rain, — they are cracked and split, and other circumstances being equal, they crack and split where the cohesion of the mass is least. Take then a mass of partially consolidated mud. Assuredly such a mass is divided and subdivided by surfaces along which the cohesion is comparatively small. Penetrate the mass, and you will see it composed of numberless irregular nodules bounded by surfaces of weak cohesion. Figure to your mind's eye such a mass subjected to pressure, — the mass yields and spreads out in the direction of least resistance ;* the little nodules become con- verted into laminae, separated from each other by surfaces of weak cohesion, and the infallible result will be that such a mass will cleave at right angles to the line in which the pressure is exerted. Further, a mass of dried mud is full of cavities and fissures. If you break dried pipe-clay you see them in great numbers, and there are multitudes of them so small that you cannot see them. I have here a piece of glass in which a bubble was enclosed ; by the compression of the glass the bubble is flattened, and the sides of the bubble approach each other so closely as to exhibit the colours of thin plates. A similar flattening of the cavities must take place in squeezed mud, and this must materially facilitate the cleavage of the mass in the direction already indicated. Although the time at my disposal has not permitted me to develope this thought as far as I could wish, yet for the last twelve months the subject has presented itself to me almost daily under one aspect or another. I have never eaten a biscuit during this period in which an intellectual joy has not been superadded to the more sensual pleasure ; for I have remarked in all such cases cleavage developed in the mass by the rolling-pin of the pastrycook or confectioner. I have only to break these cakes, and to look at the fracture, to see the laminated structure of the mass. Nay, I have the means of pushing the analogy further ; I have here some slate which was subjected to a high temperature during the confla- gration of Mr. Scott Russell's premises. I invite you to compare this structure with that of a biscuit : air or vapour within the mass has caused it to swell, and the mechanical structure it reveals is precisely that of a biscuit. I have gone a little into the mysteries of baking while conducting my inquiries on this subject, and have received much instruction from a lady friend in the manufacture of puff-paste. Here is some such paste baked in this house under my own superintendence. The cleavage of our hills is accidental cleavage, but this is cleavage with intention. The volition of the pastrycook has entered into the formation of the mass, and it has been his aim to preserve a series of surfaces of structural weakness, * It is scarcely necessary to say that if the mass -v^ere squeezed equally in all directions no laminated structure could be produced ; it must have room to yield in a lateral direction. x2 306 P'ff^f' Tyndall, on the Comparative View of [June 6, along which tlie dough divides into layers. PufF-paste must not be handled too much, for then the continuity of the surfaces is broken ; it ought to be rolled on a cold slab, to prevent the butter from melting, and diffusing itself through the mass, thus rendering it more homogeneous and less liable to split. This is the whole philosophy of puff-paste ; it is a grossly exaggerated case of slaty cleavage.* As time passed on cases multiplied, illustrating the influence of pressure in producing lamination. Mr. Warren De la Rue informs me that he once wished to obtain white-lead in a fine granular state, and to accomplish this he first compressed the mass : the mould was conical, and permitted the mass to spread a little late- rally under the pressure. The lamination was as perfect as that of slate, and quite defeated him in his effort to obtain a granular powder. Mr. Brodie, as you are aware, has recently discovered a new kind of graphite : here is the substance in powder, of exquisite fineness. This powder has the peculiarity of clinging together in little confederacies ; it cannot be shaken asunder like lycopodium ; and when the mass is squeezed, these groups of particles flatten, and a perfect cleavage is produced. Mr. Brodie himself has been kind enough to furnish me with specimens for this evening's discourse. I will cleave them before you : you see they split up into plates which are perpendicular to the line in which the pressure was exerted. This testimony is all the more valuable, as the facts were obtained without any reference whatever to the question of cleavage. I have here a mass of that singular substance Boghead cannel.f This was once a mass of mud, more or less resembling this one, which I have obtained from a bog in Lancashire. I feel some hesitation in bringing this substance before you, for, as in other cases, so in regard to Boghead cannel, science — not science, let me not libel it, but the quibbling, litigious, money-loving portion of human nature speaking through the mask of science — has so con- trived to split hairs as to render the qualities of the substance somewhat mythical. I shall therefore content myself with showing you how it cleaves, and with expressing my conviction that pressure had a great share in the production of this cleavage. The principle which I have enunciated is so simple as to be almost trivial ; nevertheless, it embraces not only the cases I have mentioned : but, if time permitted, I think I could show you that it takes a much wider range. When iron is taken from the puddling * Cream cheese, at least such as I have tried, when torn asunder by the fingers, shows a very perfect cleavage in planes perpendicular to the direction in which the mass has been squeezed. In an ordinary loaf of household bread, the portion near the under cinist may also be torn into laminae : this is perhaps \)€St seen when the bread is fresh. t For which I have to thank Mr. George E^mondson. 1856.] the Cleavage of Crystals and Slate Mocks. 307 furnace it is a more or less spongy mass : it is at a welding heat, and at this temperature is submitted to the process of rolling : bright smooth bars such as this are the result of this rolling. But I have said that the mass is more or less spongy or nodular, and, notwithstanding the high heat, these nodules do not perfectly in- corporate with their neighbours : what then ? You would say that the process of rolling must draw the nodules into fibres — it does so ; and here is a mass acted upon by dilute sulphuric acid, which exhibits in a striking manner this fibrous structure. The experi- ment was made by my friend Dr. Percy, without any reference to the question of cleavage. Here are other cases of fibrous iron. This fibrous structure is the result of mechanical treatment. Break a mass of ordinary iron and you have a granular fracture ; beat the mass, you elongate these granules, and finally render the mass fibrous. Here are pieces of rails along which the wheels of locomotives have slided ;* the granules have yielded and become plates. They exfoliate or come off in leaves ; all these effects belong, I believe, to the great class of phaenomena of which slaty cleavage forms the most promi- nent example.f Thus, ladies and gentlemen, we have reached the termination of our task. I commenced by exhibiting to you some of the phaenomena of crystallization. I have placed before you the facts which are found to be associated with the cleavage of slate rocks. These facts, as finely expressed by Helmholtz, are so many tele- scopes to our spiritual vision, by which we can see backward through the night of antiquity, and discern the forces which have been in operation upon the earth's surface " Ere the lion roared, Or the eagle soared." From evidence of the most independent and trustworthy cha- racter, we come to the conclusion that these slaty masses have been subjected to enormous pressure, and by the sure method of experi- ment we have shown — and this is the only really new point which has been brought before you — how the pressure is sufficient to produce the cleavage. Expanding our field of view, we find the self-same law, whose footsteps we trace amid the crags of Wales and Cumberland, stretching its ubiquitous fingers into the domain of the pastrycook and ironfounder ; nay, a wheel cannot roll over * For these specimens and other valuable assistance I am indebted to Mr. Williams. t An eminent authority informs me that he believes these surfaces of weak cohesion to be due to the interposition of films of graphite, and not to any tendency of the iron itself to become fibrous ; this of course does not in any way militate against the theory which I have ventured to propose. All that the theory requires is surfaces of weak cohesion, however produced, and a change of shape of such surfaces consequent on pressure or rolling. 308 Mr, Faraday on M. PetitjearCs Silvering Process, [June 13, the half-dried mud of our streets without revealing to us more or less of the features of this law. I would say, in conclusion, that the spirit in which this problem has been attacked by geologists, indicates the dawning of a new day for their science. The great intellects who have laboured at geology, and who have raised it to its present pitch of grandeur, were compelled to deal with the subject in mass ; they had no time to look after details. But the desire for more exact knowledge is increasing ; facts are flowing in, which, while they leave untouched the intrinsic wonders of geology, are gradually supplanting by solid truths the uncertain speculations which beset the subject in its infancy. Geologists now aim to imitate, as far as possible, the conditions of nature, and to produce her results ; they are approaching more and more to the domain of physics ; and I trust the day will soon come when we shall interlace our friendly arms across the common boundary of our sciences, and pursue our respective tasks in a spirit of mutual helpfulness, encouraeement, and goodwill. [J.T.] WEEKLY EVENING MEETING, Friday, June 13. SiE Roderick I. Murchison, G.C.S. F.R.S. Vice-President, in the Chair. Professor Faraday, D.C.L. F.R.S. On M. Petitjea7i*s process for Silvering Glass : some Observations on divided Gold. M. Petitjean's process consists essentially in the preparation of a solution containing oxide of silver, ammonia, nitric, and tartaric acids, able to deposit metallic silver either at common or somewhat elevated temperatures ; and in the right application of this solution to glass, either in the form of plates or vessels. 1540 grains of nitrate of silver being treated with 955 grains of strong solution of ammonia, and afterwards with 7700 grains of water, yields a solution, to which when clear 170 grains of tartaric acid dissolved in 680 grains of water is to be added, and then 152 cubic inches more of water, with good agitation. When the liquid has settled, the clear part is to be poured off; 152 cubic inches of water to be 1856.] and on Divided Gold. 809 added to the remaining solid matter, that as much may be dissolved as possible ; and the clear fluids to be put together and increased by the further addition of 61 cubic inches of water. This is the silver- ing solution, No. 1 ; a second fluid. No. 2, is to be prepared in like manner, with this difference, that the tartaric acid is to be doubled in quantity. The apparatus employed for the silvering of glass plate consists of a cast-iron table box, containing water within, and a set of gas-burners beneath to heat it : the upper surface of the table is planed and set truly horizontal by a level, and covered by a varnished cloth : heat is applied until the temperature is HO^Fah. The glass is well cleaned, first with a cloth ; after which a plug of cotton, dipped in the silvering fluid and a little polishing powder, is carefully passed over the surface to be silvered, and when this application is dry it is removed by another plug of cotton, and the plate obtained perfectly clean. The glass is then laid on the table, a portion of the silvering fluid poured on to the surface, and this spread carefully over every part by a cylinder of india-rubber stretched upon wood which has previously been cleaned and wetted with the solution ; in this manner a perfect wetting of the surface is obtained, and all air bubbles, &c. are removed. Then more fluid is poured on to the glass until it is covered with a layer about the j^^th of an inch in depth, which easily stands upon it ; and in that state its temperature is allowed to rise. In about 10 minutes or more silver begins to deposit on the glass, and in 15 or 20 minutes a uniform opaque coat, having a greyish tint on the upper surface, is deposited. After a certain time the glass em- ployed in the illustration was pushed to the edge of the table, was tilted that the fluid might be poured off", was washed with water, and then was examined. The under surface presented a perfectly brilliant metallic plate of high reflective power, as high as any that silver can attain to ; and the coat of silver, though thin, was so strong as to sustain handling, and so firm as to bear polishing on the back to any degree, by rubbing with the hand and polishing powder. The usual course in practice, however, is, when the first stratum of fluid is exhausted, to remove it, and apply a layer of No. 2 solution ; and when that has been removed and the glass washed and dried, to cover the back surface with a protective coat of black varnish. When the form of the glass varies, simple expedients are employed ; and by their means either concave or convex, or corrugated surfaces are silvered, and bottles and vases are coated internally. It is easy to mend an injury in the silvering of a plate, and two or three cases of repair were performed on the table. The proposed advantages of the process are, — the production of a perfect reflecting surface ; the ability to repair ; the mercantile economy of the process (the silver in a square yard of surface is worth \s. Sd.) ; the certainty, simplicity, and quickness of the operation ; and, above all, the dismissal of the use of mercury. In 810 Mr. Faraday [June 13, theory the principles of the process justify the expectations, and in practice nothing as yet lias occurred which is counter to them. With regard to the second part of the evening's discourse, the speaker said he had been led by certain considerations to seek experimentally for some effect on the rays of light, by bodies which when in small quantities had strong peculiar action upon it, and which also could be divided into plates and particles so thin and minute as to come far within the dimensions of an undula- tion of light, whilst they still retained more or less of the power they had in mass ; and though he had as yet obtained but little new information, he considered it his duty, in some degree, to report progress to the Members of the Royal Institution. The vibrations of light are, for the violet ray 59,570 in an inch, and for the red ray 37,640 in an inch ; it is the lateral portion of the vibration of the ether* which is by hypothesis supposed to affect the eye, but the relation of number remains the same. Now a leaf of gold as supplied by the mechanician is only 2To!7roiT ^^ ^^ moh. in thickness, so that 7^ of these leaves might be placed in the space occupied by a single undulation of the red ray, and 5 in the space occupied by a violet undulation. Gold of this thickness and in this state is transparent, transmitting green light, whilst yellow light is reflected ; there is every reason to believe also that some is absorbed, as hap- pens with all ordinary bodies. When gold leaf is laid upon a layer of water on glass, the water may easily be removed, and solutions be substituted for it ; in this way a solution of chlorine, or of cya- nide of potassium, may be employed to thin the film of gold ; and as the latter dissolves the other metals present in the gold, (silver, for instance, which chlorine leaves as a chloride,) it gives a pure result ; and by washing away the cyanide, and draining and drying the last remains of water, the film is left attached to the glass : it may be experimented with, though in a state of extreme tenuity. Examined either by the electric lamp, or the solar spectrum, or the microscope, this film was apparently continuous in many parts where its thickness could not be a tenth or twentieth part of the original gold leaf. In these parts gold appeared as a very transparent thing, reflecting yellow light and transmitting green and other rays ; it was so thin that it probably did not occupy more than a hundredth part of a vibration of light, and yet there was no peculiar effect produced. The rays of the spectrum were in succession sent through it ; a part of all of them was either stopped or turned back, but that which passed through was unchanged in its character, whether * Analogous transverse vibration may easily be obtained on the surface of water or other fluids, by the process described in the Philosophical Transac- tions for 1831, p. 336, &c. 1856.] on Divided Gold, 31 1 the gold plate was under ordinary circumstances, or in a very in- tense magnetic field of force. When a solution of gold is placed in an atmosphere containing phosphorus vapour the gold is reduced, forming films that may be washed and placed on glass without destroying their state or condi- tion : these vary from extreme thinness to the thickness of gold leaf or more, and have various degrees of reflective and transmissive power ; they are of great variety of colour, from grey to green, but they are like the gold leaves in that they do not change the rays of light. When gold wires are deflagrated by the Leyden discharge upon glass plates, extreme division into particles is effected, and deposits are produced, appearing, by transmitted light, of many varieties of colour, amongst which are ruby, violet, purple, green, and grey tints. By heat many of these are changed so as to transmit chiefly ruby tints, retaining always the reflective character of gold. None of them aflTect any particular ray selected from the solar spectrum, so as to change its character, otherwise than by reflection and absorption ; what is transmitted still remains the same ray. When gold leaf is heated on glass the heat causes its retraction and run- ning together. To common observation the gold leaf disappears, and but little light is then reflected or stopped : but if pressure by a polished agate convex surface be applied to the gold in such places, reflective power reappears to a greater or smaller degree, and green light is again transmitted. When the gold films by phos- phorus have been properly heated, pressure has the same eflect with them. If a piece of clean phosphorus be placed beneath a weak gold solution, and especially if the phosphorus be a clear thick film, obtained by the evaporation of a solution of that substance in sul- phide of carbon, in the course of a few hours the solution becomes coloured of a ruby tint ; and the effect goes on increasing, sometimes for two or three days. At times the liquid appears clear, at other times turbid. As far as Mr. Faraday has proceeded, he believes this fluid to be a mixture of a colourless transparent liquid, with fine par- ticles of gold. By transmitted light, it is of a fine ruby tint ; by reflect- ed light, it has more or less of a brown yellow colour. That it is merely a diff*usion of fine particles is shown by two results ; the first is, that the fluid being left long enough the particles settle to the bottom : the second is, that whilst it is coloured or turbid, if a cone of the sun's rays (or that from a lamp or candle in a dark room) be thrown across the fluid by a lens, the particles are illuminated, reflect yellow light, and become visible, not as independent particles, but as a cloud. Sometimes a liquid which has deposited much of its gold, remains of a faint ruby tint, and to the ordinary observation, transparent ; but when illuminated by a cone of rays the suspended particles show their presence by the opalescence, which is the result of their united action. The settling particles, if in a flask, appear Vol. II. Y 312 Mr. Faraday on Divided Gold. [June 13, at the bottom, like a lens of deep coloured fluid, opaque at the mid- dle, but deep ruby at the edges ; when agitated they may be again diffused through the liquid. These particles tend to aggregate into larger particles, and produce other effects of colour. It is found that boiling gives a certain degree of permanence to the ruby state. Many saline and other substances affect this ruby fluid : thus, a few drops of solution of common salt being added, the whole gradually becomes of a violet colour ; still the particles are only in suspension, and when illuminated by a lens are a golden yellow by reflected light : they separate now much more rapidly and perfectly by deposition from the fluid than before. Some specimens, however, of the fluid, of a weak purple or violet colour, remain for months without any appearance of settling, so that the particles must be exceedingly divided ; still the rays of the sun or even of a candle in a dark room, when collected by a lens, will manifest their presence. The highest powers of the microscope have not as yet rendered visible either the ruby or the violet particles in any of these fluids. Glass is occasionally coloured of a ruby tint by gold ; such glass, when examined by a ray of light and a lens, gives the opalescent effect described above, which indicates the existence of separate par- ticles ; at least such has been the case with all the specimens Mr. Faraday has examined. It becomes a question whether the con- stitution of the glass and the ruby fluids described is not, as regards colour, alike. At present, he believes . they are ; but whether the gold is in the state of pure metal, or of a compound, he has yet to decide. It would be a point of considerable optical importance if they should prove to be metallic gold ; from the effects presented when gold wires are deflagrated by the Leyden discharge over glass, quartz, mica, and vellum, and the deposits subjected to heat, pres^ sure, &c., he inclines to believe they are pure metal. [M. F.] 1856.] General Monthly Meeting. 313 GENERAL MONTHLY MEETING, Monday, July 7. William Pole, Esq. M.A. F.R.S. Treasurer and Vice-President, in the Ghair. The Right Hon. Edward Cardwell, M.P. Frederick Ducane Godman, Esq. and George Knight Erskine Fairholme, Esq. were duly elected Members of the Royal Institution. Frederick Wm. Irby, Esq. was (tdmitted a Member of the Royal Institution. The following Presents were announced, and the thanks of the Members returned for the same : — From Acland, Thomas Dyke, Esq. — A "Word in Season : or, How to grow Wheat with Profit. 15th Edition. 8vo. 1856. Ashmolean Society, Ox/^orc?— Transactions, Vols. I. and II. 8vo. 1835-52. Proceedings, Nos. 1-3. 8vo. 1832-55. Report on the Mortality and Public Health of Oxford, in 1849-50. 8vo. 1854. Asiatic Society of Bengal — Journal, No. 252. 8vo. 1855. Asiatic Society, i?oyaZ— Journal, Vol. XVI. Part 2. 8vo. 1856. Astronomical Society, Boyal— Monthly Notices. Vol. XVI. No. 7. 8vo. 1856. ^ufAoT'— Remarks on the Decimal System of Coinage. 8vo. 1856. Bath and West of England Society— J oarudd, Parts 1, 2, and 4. 8vo. 1853-6. Bayley, Francis, Esq. M.R. /.—Fifty-one Miscellaneous Tracts, 1 648-1 72 1 . 4to. Fifty Sermons, Charges, &c. 1678-1794. 4to. Bell, Jacob, Esq. ilf.^./.— Pharmaceutical Journal for July, 1856. 8vo. Boosey, Messrs. {the Publishers)— The Musical World for June, 1856. 4to. Bombay Geographical Society — Transactions, Vol. XII. 8vo. 1856. Bombay Medical ^oar J— Deaths in Bombay in 1854.— Correspondence respect- ing Burials in Bomb^. 4to. 1855. Bradbury, Henry, Esq. M.R. I.— The Ferns of Great Britain and Ireland. By T. Moore, F.L.S. Edited by J. Lindley, Ph.D. F.L.S. Part 15. fol. 1856. Brewer, Tliomas, Esq {the Author)— Memoir of John Carpenter, Town-Clerk of London in the reigns of Henry V. and Henry VI. 8vo. 1856. British Architects, Royal Institute o/"— Proceedings in June, 1856. 4to. Carpenter, W. B. M.D. F.R.S. (the Author) — Researches on the Forameni- fera. (Phil. Trans.; 4to. 1856. Crichton, Alexander, Esq. M.R.I.—CEurres de M. De Pradt. 24 vols. 8vo. Paris, 1817-28. Commissioners in Lunacy — Ninth Report. 8vo. 1856. Dublin Geological Society— J o\im&]. Vols. I.-VI. 8vo. 1834-55. East India Company, the Ho«.— Magnetical and Meteorological Observations at Bombay in 1853. 4to. 1855. 314 General Monthly Meeting. [July 7, 1§56. Editom—TYie Medical Circular for June 1856, 8vo. The Practical Mechanic's Journal for June 1856. 4to. The Journal of Gas-Lighting for June 1856. 4to. The Mechanic's Magazine for June 1856. 8vo. The Athenajum for June 1856. 4to. The Engineer for June 1856. fol. The Literarium for June 1856. fol. Falconer, H. M.D. (the Author) — On Prof. Huxley's Attempted Refutation of Cuvier. 8vo. 1856. Faraday, Professor, D.C.L. F.R.S. — Monatsberichte der Konigl. Preuss. Akademie, Mai, 1856. 8vo. Berlin. Memorie della Reale Accademia della Scienze di Torino. Serie Seconda. TomoXV. 4to. 1855, Almanach fur 1855. 16mo. Feste-Rede und Denkrede. 4to, 1855. Annalen der Koniglichen Stern warte bei Munchen : von Dr. J, Lamont. Band VII. and VIII. 8vo. 1854-5. Bayerische Akademie — Abhandlungen der Math. Phys. Classe. Band VII. Abth. 3. 4to. 1 855. Geneve, Soci^td'de Pht/sique—Memoires. Tome XIV. Partie 1. 4to. 1855. Geographical Society, Royal — Proceedings, No. 3. 8vo. 1856. Journal, Vol. XXV. 8vo. 1855. Graham, George, Esq. Registrar-General — Report of the Registrar-General for June 1856. 8vo. Jennings, Richard, Esq. M.A. M.R.I, {the ^wf^or)— Social Delusions concern- ing Wealth and Want. 16mo. 1856. Knight, Mr. G. {the Publisher) — Tracts on Photographic Manipulation, by J. How, G. Le Gray, and T. Hennah. 12mo. 1855. Law, W.J. Esq. A.M. {the Author ) —Reply to Mr. Ellis's Defence of his Theory on the Route of Hannibal. 8vo. 1856. Macloughlin, D. M.D. M.R.I, {the Author)— On Cholera. 8vo. 1856. Macrory, E. Esq. M.R.I. — Lucani Pharsalia cum J. Sulpitii Verulani et Omniboni Vicentini Commentariis. fol. [Ven. 1493.] Mendicity Society — Reports. 8vo. 1846-55. Newton, Messrs. — London Journal (New Series), July 1856. 8vo. Novello, Mr. {the Publisher)^The Musical Times for June 1856. 4to, Northumberland, the Duke of, K.G. F.R.S. President R.I. — Descriptive Catalogue of a Cabinet of Roman Family Coins, belonging to the Duke of Northumberland, K.G. by Rear-AdmiraJ W. H. Smyth. 4to. 1856. Petermann, A. Esq. (the Author) — Mittheilungen auf dem Gesammtgebiete der Geographic. 1856. Heft 3, 4, 5. 4to. Gotha, 1856. Photographic Society — Journal, No. 43. 8vo. 1856. Royal Society of London — Proceedings, No. 21. 8vo. 1856. Report of the Committee of Physics and Meteorology. 8vo. 1840. Catalogue of the Library of the Royal Society. 4to. 1825. Catalogues of Miscellaneous Literature and MSS. 2 vols. 8vo. 1840-1, Astronomical Observations, by Rev. T. Catton. 4to. 1853. Sharp, Hercules, Esq. M.R.I. — Archivio Centrale di Stato in Firenze. 8vo. 1855. Society of Arts— Jonmail for June 1856. 8vo. Statistical Society— Jonmsil, Vol. XIX. Part 2. 8vo. 1856. Tennant, Professor, and Rev. W. Mitchell {the Authors) — Mineralogy and Crystallography. 12mo. 1856 Vereinszur BeforderungdesGewerbfteisses in Preussen — Mdrz und April 1856. 4to. Vincent, B. Assist.-Sec. R.I.—The Anglo-Saxon Church. By H. Soames. 8vo. 1835. iilojjal Sttgtitution ot QSxtat 33xitmn. GENERAL MONTHLY MEETING, Monday, November 3. William Pole, Esq. M.A. F.R.S. Treasurer and Vice-President, in the Chair. Sir Charles Henry Rouse Boughton, Bart. George Burdon, Esq. and "William Frederick Robinson, Esq. were duly elected Members of the Royal Institution. The special thanks of the Members were returned to the Right Hon. Sir Benjamin Hall, Bart. M.P. for his present of a copy of " Architectural Antiquities of the Collegiate Church of St. Stephen's Chapel, Westminster. By F. Mackenzie." fol. 1844. The following Presents were announced, and the thanks of the Members returned for the same : — From— Actuaries, Institute of— Assurance Magazine. Nos. 24, 25. 8vo. 1856. Agricultiircd Society, Royal — Journal, Vol. XVII. Part 1. 8vo. 1856. Asiatic Society of Bengal — Journal, Nos. 253-255. 8vo. 1855. Astronomical Society, Boyal— Monthly Notices. Vol. XVI. No. 8. 8vo. 1856. Barclay, A. W. M.D. M.R.I, {the Author) — The Progress of Preventive Medicine and Sanitary Measures. 8vo. 1856. Bell, Jacob, Esq. itf.i?./.— Pharmaceutical Journal for Aug. to Nov. 1856. 8vo. Booseif, Messrs. (the Publishers)— The MusicalWorld for July to Oct. 1856. 4to. Bradbury, Henry, Esq. M.R.I. — The Ferns of Great Britain and Ireland. By T. Moore, F.L.S. Edited by J. Lindley, Ph.D. F.L.S. Parts 16, 17. fol. 1856. British Architects, Royal Institute o/"— Proceedings in Session 1 855-6. 4to. British Association — Report of the Meeting at Glasgow in 1855. 8vo. 1856. British Museum, Trustees o/'4 w^Aor)— Analysis of the Statistics of the Clearing-house during 1839. 8vo. 1856. Bell, Jacob, Esq. MM. I. — Pharmaceutical Journal for Jan. 1857. 8vo. Boosey, Messrs. (the Publishers) — The Musical World for Jan. 1857. 4to. British Architects, Royal Institute o/'— Proceedings in Jan. 1857. 4to. British and Foreign Bible Society — Catalogue of their Library, by G. BuUen. 8vo. 1857. Carpenter, W. B. M.D. F.R.S. {the Author) — Researches on the Foraminifera. Part 2. 4to. (Phil. Trans.) 1856. Copland, James, M.D. F.R.S. {the Author)— On the Drainage and Sewage of London. 12mo. 1857. De la Rue, Warren, Esq. F.R.S. Jf.i?./.— Engraving of Jupiter, as seen with a Newtonian Equatoreal of 13 inches aperture, Oct. 25, 1856. Editors— The Medical Circular for Dec. 1856, and Jan. 1857. 8vo. The Practical Mechanic's Journal for Dec. 1856, and Jan. 1857. 4to. The Journal of Gas- Lighting for Dec. 1856, and Jan. 1857. 4to. The Mechanic's Magazine for Dec. 1856, and Jan. 1857. 8vo. The Athenaeum for Dec. 1856, and Jan. 1857. 4to. The Engineer for Dec. 1856, and Jan. 1857. fol. The Literarium for Dec. 1856, and Jan. 1857. Faraday, Professor, D.C.L. F.R.S. — Monatsberichte der Konigl. Preuss. Akademie, Sept. und Okt. 1856. 8vo. Berlin. Franklin Institute of Pennsylvania — Journal, Vol. XXXI. No. 5 ; and Vol. XXXII. Nos 3, 4, 5, 6. 8vo. 1856. Gamgee, Joseph S., Esq. {the Author) — Researches in Pathological Anatomy and Clinical Surgery. 8vo. 1856. On the Advantages of the Use of the Starched Apparatus in the Treatment of Fractures, &c. 8vo. 1853. Reflections on Petit's Operation. 8vo 1855. Osservazioni sul Regime Dietetico. 8vo. 1853-4. Geographical Society, Royal — Proceedings, No. 6. 8vo. 1857. Gladstone, Dr. J. H. F.R.S. M.R.I, {the Author) — Papers on Chemical Affinity, &c. 4to. and 8vo. Glosener, M. (the Author) — Recherches sur la T^legraphe Electrique. 8vo. Li^ge, 1855. Graham, George, Esq. (Registrar-General) — Report of the Registrar-General for Dec. 1856, and .Jan. 1857. 8vo. 1857.] General Monthly Meeting. 835 Hamilton, Sir Charles J. J. Bart. C.B. il/.i?. /.—Pauli Jovii Opera, fol 1578. Landois, H. {the ^ wf^or )— Causes de la Coloration des Corps, &c. 8vo. 1857. Lewiuy Malcolm, Esq. M.R.I, {the Author). — On the Government of Oude. 8vo. 1857. Locke, Mr. W. {the Hon. 5cc.>-Reports of the Ragged School Union, 1855-6. 8vo. Ragged School Union Magazine. 8vo. 1856. Londesborough, The Lord, K.H. Jli.i?./.— Miscellanea Graphica, No. 11. 4to. 1857. Macilwain, George, Esq. M.R.L {the Author) — Memoir of John Abemethy. 3rd. Ed. 8vo. 1856. Madrid, Real Academia de Cicnciaa -Memorias. Tom. III. & IV. 4to. 1856. National Life-Boat Institution— The Life-Boat Journal for 1852-56. 8vo. Newton, Messrs.— London Journal (New Series), Dec. 1856, and Jan. 1857. 8vo. Novella, Mr. {the Publisher )'-The Musical Times for Dec. 1856, and Jan. 1857. 4to. Pepys, John, Esq. i»f. /?./.— "Shall " and " Will," or Two Chapters on Future Auxiliary Verbs. By Sir E. W. Head, Bart. l6to. 1856. Poey, M. Andr^ (the ^a^or)— Several Tracts on the Meteorology, Earth- quakes, &c., of Cuba. 1855-56. Photographic Society—J onmaX, Nos. 49, 50. 8vo. 1856. Rennie, George, Esq. F.R.S. — Report from the Mersey Inquiry Committee. 8vo. 1856. Roxburgh, W. M.D. M.R.I.—The Confession of Faith, &c., of the Church of Scotland, &c. 16lo. 1845. Savage, Miss Anne — Practical Hints on Decorative Printing, with Illustrations engraved on Wood, and printed in Colours at the Type Press. By Wm. Savage, fol. 1822. Scoffem, John, M. B. {the ^ M