: i 3 » H 5 t reese retarered pir 4 ‘ PROCEEDINGS PHILOSOPHICAL SOCIETY OF GLASGOW. WOT TV. MDCCCLV.—MDCCCLX. PUBLISHED FOR THE SOCIETY BY RICHARD GRIFFIN & COMPANY, LONDON AND GLASGOW. — MDCCCLX, GLASGOW: ; PRINTED BY BELL AND BAIN, ST. ENOCH SQUARE. CONTENTS OF VOLUME IV. President’s Address, 1855, Office-Bearers, : 6 3 : 6 Abstract of Treasurer’s Accounts, . F Memorial on the Ordnance Survey, = 4 : cS “ips : I.—Spontaneous Fracture of Cast Iron, by W. J. Macquorn Rankine, LL.D., IL—On Metallurgy among the Ancient Hebrews, by Mr. James Napier, . I{1.—On the mode in which the Water of Loch Katrine may be obtained of Uniform Temperature at all seasons, ° : : . ewe IV.—On the Stability of Factory Chimneys, by W. J. Mgcquorn Rankine, [OUPADE, eae, Coca ny above Gales ov eel 7 NOUR Sn ea V.—Notice of Discovery of a new Granite Tract in Arran, by Mr. James Bryce, M.A., F.G.S., : aoa lery (ite : : aea A VI.—Report on the Low Temperatures of the Spring Months of the year 1855, by Mr. James Bryce, M.A., F.G.S., . F - A : : President’s Address, 1856, . 3 : i ‘ : . : n Abstract of Treasurer’s Accounts, : . 5 : . 5 . VII.—Metallic Iron in Trap Rock from Lochwinnoch, by Dr. Thos. Anderson, Office-Bearers, . 2 : - . 5 : A : ¢ 2 VIII.—On the Discovery of Native piste in the Trap Rocks near Barrhead, by Mr. James Bryce, M.A. F.G.S.,. 6 5. geist Chee IX.—On Bee ee Strata in the Island of Bute, by Mr. James Bryce, M.A.,, F.G.S., apse ete te ie ee Geet eee nis X.—On the Geological Relations of certain ore Veins recently discovered in Bute, by Mr. James Bryce, M.A., F.G.S.,_ . ‘ ° . 7 XI.—An Adaptation of the Philosophy of Newton, Leibnitz, and Boscovitch to the Atomic Theory, by John G. Maevicar, D.D., Moffat, . c XII.—On Bessemer’s Process for Manufacturing Iron, by Mr. Wm. Cockey, . XI1J.—On the Education of the Working Classes, and fie Best Means of Pro- moting it, by Mr. George Anderson, . : Se ye ec XIV.—On the Phenomena and Causes of the Adaptation of the Eye to Distinct Vision at Different Distances, by Dr. Allen Thomson, . : : XV.—On some Copper and other Metallic Ores from Tarbet, on Loch Long, by Mr. James Bryce, M.A., F.G.S., ; : 5 . : , XVI.—On some Marine Fossils lately found in a quarry within the city of Glasgow, by Mr. James Bryce, M.A., F.G.S., . r 3 6 . XVII.—Notice of some Iron Ores from Nova Scotia, by Mr. James Bryce, M.A., F.G.S., =) Sahe SP, og: Ot ONAL Secale hie XVIII.—On a new system of Sewage, by Mr. Walter M‘Farlane, “ 5 XIX,—Early History and Proceedings of the Society, by Mr. W. Keddie, Abstract of Treasurer’s Accounts, 4 : : ¢ 3 f XX.—Early History and Proceedings of the Society, by Mr. W. Keddie, Office-Bearers, C ° c - és : c - - = XXI.—On certain Phenomena connected with Rotatory Motion, the Gyroscope, Precession of the Equinoxes, and Saturn’s Rings, by Mr. Edmund Hunt. With Diagrams, . A : : : : 5 ; : XXII.—On the Recent Progress and Present State of the Sciences of Meteorology and Terrestrial Magnetism. Part I. By Mr. James Bryce, M.A.,F.G.S., LU a Neste Conductivity of samples of Copper Wire, by Professor W. omson, Sem gata sis | Cain ROMER erste eth oi eae a ou ts XXIV.—On the Recent Progress of our Knowledge of the Chemical Elements, by Dr. Thomas Anderson, . 4 . A ° : ; 4 XXV.—On Incrustations in Steam Boilers, by Mr. James Napier, . : A XXVI.—On a Method of Voting at Limited Liability Companies more Uniform than the present, and its Expression by a Mathematical Formula, by Mr. James R. Napier, c . y 129 130 158 185 187 191 199 ly CONTENTS. PAGE XXVII.—Additional Notes on Rotatory Motion, by Mr. Edmund Hunt, . . 201 XXVIII. a a on the Progress and State of Applied Mechanics, by Mr. James Napier, Mr. Walter Neilson, and W. J. soe a Rankine, LL.D., 207 XXIX.—Recent Acquisitions made by. Russia at the expense of the Chinese ae ae of Manchooria, with some Account of the River Amoor, in its physical aspects and as a pathway for Commies, by W. G. Blackia, Ph. D., F.R.G.S. With a ae iP ee ; 231 President’s Address, 1859, : : ~ e 3 ae 249 Abstract of Treasurer's ‘Account, “ = 4 : F . 250 Office-Bearers, . 2 3 5 : = 251, 364 Periodical Printing of Proceedings, : . : 252, 258 XXX.—On the Cinephantic Colour Top, by Mr. Edmund Hunt, E 252 REXEL Notes of a Visit to Iceland in the Summer of 1859, by Mr. David Mackinlay, 259 XXXII.—Recent Investigations of M. Le Verrier on the Motion of Mercury, by William Thomson, M.A., LL.D., F.R.S., Professor of Natural Philosophy in the University of Glasgow, 5 263 XXXIII.--On Photographed Images of Electric Sparks, by Professor William Thomson, . 266 XXXIV.—Note on the Bursting of the Reservoirs of Crinan Canal, by Mr. William Keddie, . a = . 267 Election of Honorary Members, 271 XXXV.—On the Variation of the Periodic Times of the Earth and Inferior Planets, produced by Matter Falling into the Sun, by Professor William Thomson, 272 XXXVIL—On Instruments and Methods for observing Electricity, by Professor William Thomson, A 274 XXXVII.—On Inerustations of Boilers using Sea-Water, by Mr. James R. Napier, 282 XXXVIII.—On the Density of Steam, by W. J. Maequorn Rankine, LL.D., F.R.S. L. and E., Professor Te Civil eee in the University of Glasgow, . 285 XXXIX.—Observations on Sensations experienced " while climbing the more elevated Mountains of the Andes in Peru and Bolivia, by Mathie Hamilton, M.D., formerly Medical Officer to the London, Potosi, and Peruvian Mining Company, Physician to Military parities in Peru, &c., 287 XL.—On Spots on the Sun, by Mr. Robert Hart. With Illustrations, sme 202 XLI.— Observations on the Supply of Coal and Ironstone, from the Mineral Fields of the West of Scotland, by Mr. William sas poke and Mining Engineer. With Map and Section, . 292 XLII.—Remarks on Glass Painting, by Mr. C. Heath Wilson, 309 XLIII. ame oe Incrustation of Marine Boilers, by William Wallace, Ph. D., 8., . 317 XLIV.—On Electrical Dischar ges in Rarefied Media, by Dr. Wallace, “ 320 XLV.—On Trap Dykes, between Cordon and south end of Whiting Bay, Island of Arran, by Mr. James Napier, Chemist, . 321 XLVI.—On the Force of the Voltaic Current, by George Blair, M. A., 4 324 XLVII.—Historical Notes of Copper Smelting, by Dr. Frankie H. Thomson, - 825 XLVIII.—On a New Process of Ornamenting Glass, by Mr. James ae, Chemist, 4 345 XLIX.—On the Spinal Cord and Nerves, by Allen Thomson, M. D., E.R oe Professor of Anatomy in the University of Glasgow, : 348 L.—On the Distribution and Probable Origin of the Petroleum, or " Rock Oil, of Western Pennsylvania, New York, and Ohio, by Henry D, Rogers, F.R.S., Hon. F.R.S.E., F.G.S., Professor of Natural es tory in the University of Glasgow, 305 LI.—On the Ageing of Mordants in Calico Printing, by Walter Crom, F ER, 3 360 Abstract of Proceedings of Session 1858-89, . ° 362 The late William Murray, Esq. of Monkland, ; 362 LII,—On some Points in the henley of Bec Refining we Dr. William Wallace, 367 PROCEEDINGS OF THE PHILOSOPHICAL SOCIETY OF GLASGOW. FIFTY-FOURTH SESSION. Anderson’s University Buildings, November 7, 1855. Tne Session of the Philosophical Society of Glasgow was opened this evening,—Dr. Allen Thomson, President, in the Chair. The President delivered an address, in which he made a review of the proceedings at the recent meeting of the British Association in Glasgow. Among other observations, he said, “ The success of the meeting, which is universally acknowledged, was manifested not less by the number and distinction of the scientific men who attended and took a part in the proceedings, than by the extent and importance of the scientific memoirs brought forward and discussed. “The total number of members enrolled at this meeting was 2,140, the largest attendance at any meeting of the Association since its com- mencement, with the exception of that at Newcastle in 1838. “The sum of money received for tickets from members and associates amounted to £2,314; the whole of which, owing to the liberality of the private subscriptions in Glasgow for defraying the local expenses, has been handed over to the Association for application to scientific objects. “The local subscription amounted to £1,450. “The number of papers read and presented was 349, distributed through the several sections as follows :— A. Mathematical and Physical Science, . . - ° : » 55 B. Chemical Science, 2 ° : “ ; : . » 62 C. Geology, . - : : ; : . 46 D. Zoology and ssitatie? 47, _ 77 Subsection D, Physiology, 30, E. Geography and iii, - : ; : : - - 86 F. Statistics, . - : , = F - ; : Rent! G. Mechanical Science, . . : : ( < ; : - 42 Total, : - » 849 Vou. IV.—No. 1. B 2 British Association. being nearly an average of forty-three and a-half papers for each of the eight sections. “ The sectional meetings took place on six days, and of these meetings there were forty-two in all. They lasted on an average four hours, which gives an aggregate amount of time of 168 hours devoted to the reading and discussing the various communications. This time—equal to four- teen days of twelve hours each—would be equal to that passed in six or seven sessions of the meetings of the Glasgow Philosophical Society. “ There is good ground, therefore, for satisfaction in the result of the meeting, and we have reason to congratulate ourselves that science has prospered in the hospitable care of our city. To this success a variety of cireumstances have no doubt contributed, among which may be mentioned, first, the attractions which Glasgow presents as one of the greatest seats of the successful application of scientific principles to important, useful, and practical objects ; second, the increasing influence and continued improvement in the management of the British Asso- ciation itself; and, third, the strenuous and well-directed efforts of those immediately charged with the arrangements for the meeting. “Jn reflecting now, as it is natural for us to do, on the advantages that may have been derived from such a meeting, I doubt not that every one will be disposed to give a foremost place to the pleasure he has received, and the improving influence he has experienced from seeing the interesting countenances, hearing the eloquent and learned dis- courses, and making the acquaintance of many eminent men whose names may have been long known to him as the most distinguished in their several departments. In some instances this is perhaps a grati- fication of mere curiosity ; in others it is positively useful in enabling us to appreciate more justly, and to enjoy more fully the writings of authors whom we have not previously seen. “Not less marked than the feeling now alluded to is the conscious- ness, which every cultivator of science must be aware of, that he has received a great and fresh stimulus to exertion from the example of the many bright ornaments of science who are congregated together at the Association meetings. We are pleased to witness the respect which is paid by those highest in social rank to the distinction of scientific attainments; and we are glad also to perceive that many of those whose social position might have made them regardless of science, have attained to considerable eminence in various of its branches; but it is still more satisfactory to find, that, in this great republic of science, obscurity in social rank is no bar to fame, and scientific distinction is in proportion only to the value of the contribution which is brought forward by any of its members. British Association. 3 “ Whatever may be thought of the frequency of the meetings of the Association in general, it cannot be held by any one who has witnessed our recent assemblage, that an interval of fifteen years was too short a period before the repetition of the meeting in Glasgow took place. Not only has a sufficient number of fresh votaries of science appeared in the field since the time of the first visit, but in the hands of these and of the veterans, science and its applications to useful arts have not slumbered in this town or its vicinity, but have been advanced here as elsewhere with increasing rapidity. The sketch which I shall lay before you of the principal communications brought before the several Sectional meetings, will show that the value of the scientific facts and importance of the principles discussed at_ this meeting, do not yield to any of those which have preceded it. Great and striking novelties or discoveries in science do not arise in regular periodic succession ; but valuable research, and great vigour, and fruit- fulness of suggestion, may with justice be said to have characterized the proceedings at every one of the Sectional meetings. “ Before entering upon an enumeration of the scientific business brought forward at the Sections, it is proper for me to allude shortly to the general interest which was given to the meeting by the manner in which the office of president was filled by the Duke of Argyll. All those, I am sure, who heard the eloquent and learned addresses delivered by that accomplished nobleman, must have been struck with the masterly sketch in which, at the first public meeting, he brought rapidly before them, in language equally elegant and descriptive, a history of the progress of science in the period between the first and the second meetings of the British Association in Glasgow; and the citizens of Glasgow, and of the west of Scotland, feel some degree of pride, that from among themselves had arisen one whose grace and learn- ing were calculated to add lustre to such an assemblage of the most celebrated scientific men of this and other countries.” The President then gave a short account of the more important papers brought before the several Sections, having been kindly fur- nished with the necessary materials by the Presidents or Secretaries of the several Sections. He then continued— “ After these, the greater and essential features of the meeting, I need do no more than allude to the various minor arrangements and acces- sory circumstances which contributed to its success. “The very suitable accommodation provided by the College for the various Sectional meetings—the unequalled halls which the town so liberally offered for the public assemblies, among which I must not 4 British Association. pass over the M‘Lellan Galleries—the elegant and sumptuous enter- tainment of the Lord Provost to the office-bearers of the Association— the two highly instructive and deeply interesting lectures by Pro- fessor Carpenter and Colonel Rawlinson—the Conversational meetings, Claudet’s stereopticon, and Duboseq and Nachet’s exhibition of photo- graphic pictures and minute objects by means of the electric light— the photographie exhibition in Messrs. Wylie and Lochhead’s gallery —the interesting specimens of ancient boats or canoes—the unrivalled collection of fossils of the coal formation, and of some other strata, together with the series illustrating the manufacture of iron, glass, pottery, and various other products of Glasgow industry—the excur- sions, particularly that to Arran—the marine vivaria, prepared by Dr. Miles and Dr. Paterson, in which a set of plants and animals were exhibited which many of the associates of the meeting had never before seen alive; and, lastly, the extreme liberality with which the different public institutions, and a large number of the most interesting private manufactories were opened to the Association,—these various circum- stances could not but add, in an eminent degree, to the pleasant occupation and instruction which the meeting was calculated to afford to persons of every variety of scientific taste.” On the motion of Mr. Provan, seconded by Mr. Murray of Monk- land, a vote of thanks was given to the President for his address. Mr. William Church, Accountant, was elected a member, having been proposed at the concluding meeting of last Session. Mr. Cockey, the Treasurer, called the attention of the Society to the alterations which had been made during the recess in the Hall, by which its appearance and comfort had been greatly improved. He stated that the alterations had incurred an expense of about £60, and moved that the Society grant that sum to the Council to defray the cost. The first vote on this motion was taken, and the Society agreed accordingly to grant £60 from the funds. Mr. Dawson and Mr. Bell were requested to audit the Treasurer’s Accounts. The following books and maps were presented to the Society, for which thanks were voted to the donors :— Physical and Geological Map of India, by S. B. Greenough, F.R.S., &c., presented to the Society on behalf of the Executors of that gentle- man, by Robert Hutton, Esq. of Putney Park, Surrey, F.G.S. Transactions of Royal Scottish Society of Arts, vol. iv., Part III. Proceedings of Liverpool Literary and Philosophical Society, No. 9. Memoirs of Literary and Philosophical Society of Manchester, vols. xi. and xii. Election of Office-Bearers. 5 Transactions of Historic Society of Lancashire and Cheshire, vol. vii. Proceedings of Royal Society of Edinburgh, 1854-55. “Drawings of the Machinery of the Arabia and La Plata Steam- Ships.” By Mr. David Kirkaldy. The Society then proceeded to the Fifty-fourth Annual Election of office-bearers. On the motion of Mr. Robert Blackie, seconded by Mr. Bryce, the following were elected :-— Presivent. Dr. ALLEN THOMSON. Dice-Jresidents. Mr. Atexanper Harvey. | Mr. W. J. Macquorn RankINe. Librarian. Mr. Wittiam GOURLIE. Treagurer. Mr. Witiram CocKry. Joint-Secretaries. Mr. AnexanpDeR Hasriz, M.P.| Mr. Witi1am Keppin. The Society then proceeded to elect twelve Councillors by ballot. Mr. Mathieson and Mr. M‘Harg were requested to act as scrutineers of the votes. The scrutineers having retired to examine the vote-papers, The President and Dr. Miles exhibited and described several rare marine productions. The scrutineers having given in their Report, the following were found to be elected Members of Council. Mr. Wattrr Crum. Dr. JoHN STRANG. Dr. Tuomas ANDERSON. Mr. Ropert Buackie. Mr. Jonn Connie. Mr. Witttam Ramsay. Mr. WiLi1am Murray. Mr. Watrer NEILson. Prorgessor Wm. THomson. Mr. Roserr Harr. Mr. James R. Naprer. Mr. JameEs Couper. The second vote was taken on the proposed grant of £60 to defray the expense of improving the Hall, and this grant was finally agreed to. Mr. W. J. Macquorn Rankine brought forward the following motion, of which notice was given at last meeting :— “That a Memorial be presented to the Lords of Her Majesty’s Treasury, praying that the Ordnance Survey of the improvable parts of 6 Abstract of Treasurer's Account. the counties of Lanark, Renfrew, and Dumbarton, be engraved and published [in addition to the scale already in progress] on the scale of six inches to one mile; and that a committee be appointed to communi- cate with the Commissioners of Supply of the said counties, the Town Council of Glasgow, and other public bodies, with reference to the attainment of the above object.” Mr. Bryce seconded the motion. Mr. Hastie suggested the insertion of the words, “in addition to the scale already in progress’’—with which amendment the motion was agreed to. The following committee was appointed :—Mr. Hastie, M.P.; Mr. Walter Crum; Mr. Alexander Harvey; Mr. James Bryce, jun.; Mr. William Ramsay ; Mr. W. J. Macquorn Rankine, Convener. November, 21, 1855.— The Prestpent in the Chair. Mr. David M‘Kinlay, Pollokshields; Mr. Richard Brown, North Woodside Ironworks; Mr. William Fraser, New Bridge Street; Mr. Alexander Russell, Writer, 4 South Hanover Street; and Mr. Alex- ander Harvey, jun., Machine Maker, were elected members. Mr. Cockey gave in a Report on the state of the Library, from which it appeared that the number of volumes is at present 2,421. Dr. Anderson laid on the table copies of the printed Proceedings of the Society. Mr. Cockey, the Treasurer, gave in the following abstract of his Account for Session 1854-1855 :-— 1854. Dr. Nov. 1.—To Cash in Union and Savings Banks, £89 15 8 1855. Noy. 1. — Interest on Bank Accounts,........ 2. 9 41 £938 5 7 — Entries of 31 new Members, at Diba seachisee a. dees ss cats s-cnee eae £32 11 0 — 9 Annual Payments from Original Members, at 5s. each,..........+. 2d) gat ~ 245 Annual Payments, at 15s. each, 183 15 0 218 11 O — Rent from Sabbath School Teachers, for use DUEL ANS scr csc ccscce eect ense shia te sersceneas 3 0=0 £314 16 7 Treasurers Report. 7 1854. Cr. May. .—By New Books,’.0i.. 5. .csiis.cececscas £6110 4 — Subscription to Ray Society,..... 1 1 0 — Do. to Palzontographical So- ACG Hale kreens Ataen Ut abhio} wet 03 Bel 6 Ser MURIEL coe ss dcnasa oats siiwacnexencs 6 0 0 £69 12 4 SN RN NCE Nw csles sim cite eseic nn Spt waster nasiconiveslaet L909 =— ringing Circulars, &6C.,...0..<.02s+sceessessacine 13.0 O pr See OE EAD, vo weceoeetcse-venseaee £15 0 O — Fire Insurance, ............0s0sce0 Se 11) 0 See AAS sete rc te emits kee cottecets eS GS, — Cleaning the Hall and petty CHEESES asnbis ticnws nn paesambanse Oli 4 — Rent of Merchants’ Hall for BOG IHN sha. gto netopem cies aie 217 6 23 6 5 — Salary to Librarian, ............... 45 11 0 — Fee to Officer of Andersonian BIVCREEEY ch cratadcwcone a «atte 4 0 0 — Delivering Circulars,............... 715 2 57 6 2 — New Black Boards and Mountings,..........., 4 8 8 — Alterations and Repairs in the Hall,.......... Gi 19" “1 — Balance— Cash in Union Bank, ......... 82 3 10 Do. in Treasurer’s hand,...... 119 9 84 3 7 £314 16 7 Tue PuriLosopuicaL Socrety’s Exursrtion Funp. 1855. May 15.—To Balance, per Deposit Receipt from Corpora- Han. of Glasgow,..00..«bagaysapdastyennucpmacconcuantnaesesnatne 3 In Arrear two years, and held as resigned,..........-.ccecoossoesscsessocen eecaossecse ences 12 Placed on Non-Resident List. cccsecevsoscte octusscoscccctsacs rene «p tecccn gecxeceocsescueets 3 Heit Glaspow for places mnknO Wn .c....0-t-cco-s-sucocessesenuacsacesrudvtesacss-tene-caeeeles 6 New Members elected but not come forward,.........000.sessseseceecssceeceececeseeeee ces 2 Peat ecktehonennccesy RNase ne svaued tants smenedae=cs serena echseewsdascevauneeeuceeee ate teen 4 — 30 On Dist pr 1855-56, co. PS for a square chimney } for a round chimney ; and to this the least moment of stability of the portion of the chimney above the joint D EK, should be equal. For a chimney whose axis is vertical, the moment of stability is the same in all directions. But few chimneys have their axes exactly vertical; and the least moment of stability is obviously that which opposes a lateral pressure acting in that direction toward which the chimney leans. Let G be the centre of gravity of the part of the chimney which is above the joint D E, and B a point in the joint D E vertically below it ; and let the line D E =¢ represent the diameter of that joint which traverses the point B. Let ¢ represent the ratio which the deviation of B from the middle of the diameter DE bears to the length ¢ of that diameter. Let F be the limiting position of the centre of resistance of the joint D E, nearest the edge of that joint towards which the axis of the 16 PROFESSOR RANKINE on the Stability chimney leans, and let g denote the ratio which the deviation of that centre from the middle of the diameter D E bears to the length ¢ of that diameter. Then the least moment of stability is denoted by Wee f(g) WY bs. nevectscnnetseeee (3.) The value of the co-efficient g is determined by considering the manner in which chimneys are observed to give way to the pressure of the wind. This is generally observed to commence by the opening of one of the bed-joints, such as D E, at the windward side of the chimney. A crack thus begins, which extends itself in a zig-zag form diagonally downwards along both sides of the chimney, tending to separate it into two parts, an upper leeward part, and a lower windward part, divided from each other by a fissure extending obliquely downwards from wind- ward to leeward. The final destruction of the chimney takes place, either by the horizontal shifting of the upper division until it loses its support from below, or by the crushing of a portion of the brickwork at the leeward side, from the too great concentration of pressure on it, or by both those causes combined ; and in either case the upper portion of the structure falls in a shower of fragments, partly into the interior of the portion left standing, and partly on the ground beside its base. It is obvious that in order that the stability of a chimney may be secure, no bed-joint ought to tend to open at its windward edge; that is to say, there ought to be some pressure at every point of each bed- joint, except the extreme windward edge, where the intensity may diminish to nothing; and this condition is fulfilied with sufficient accuracy for practical purposes, by assuming the pressure to be an uniformly varying pressure, and so limiting the position of the centre of pressure F', that the intensity at the leeward edge E shall be double of the mean intensity. Chimneys in general consist of a hollow shell of brickwork, whose thickness is small as compared with its diameter; and in that case it is sufficiently accurate for practical purposes to give to g the following values :— For square chimneys, g=4; | (4.) Wen ehh Glare pita od pets sie aeee petit : The following general equation, between the moment of stability and the moment of the external pressure, expresses the condition of stability of a chimney :— EGP (9 23g We rk a A. dee (5.) oe . Of Factory Chimneys. 17 This becomes, when applied to square chimneys, HpS=(h—q) We; } and when applied to round chimneys, G.) noe Ho adi ee ite ; eS _¢_ we The following approximate formule, deduced from these equations, are useful in practice. Let B be the mean thickness of brickwork above the joint D E under consideration, and b the thickness to which that brickwork would be reduced if it were spread out flat upon an area equal to the external area of the chimney. ‘That reduced thickness is given with sufficient accuracy by the formula, b=B(1— 2%); a ea erate. (7.) but in most cases the difference between 6 and B may be neglected. Let w be the weight of a cubic foot of brickwork; being from 112 Ibs. to 120 lbs. Then we have very nearly, For square chimneys, W =4wbS8; (8.) For round chimneys, W=3'14wbS;§ 0000 : which values being substituted in the equations 6, give the following formula :— 4 ] For square chimneys, H = (5-4 /) woes i ; 4 2 Rne 9.) For round chimneys, H p = (1:57 — 6:28 ¢') w bt. These formulz serve two purposes ; jist, when the greatest intensity of the pressure of the wind, p, and the external form and dimensions of a proposed chimney are given, to find the mean reduced thickness of brickwork, b, required above each bed-joint, in order to insure stability ; and, secondly, when the dimensions and form, and the thickness of the brickwork of a chimney are given, to find the greatest intensity of pressure of wind which it will sustain with safety. The shell of a chimney consists of a series of divisions, one above another, the thickness being uniform in each division, but diminishing upwards from division to division. The bed-joints between the divi- sions, where the thickness of brickwork changes (including the bed- joint at the base of the chimney), have obviously less stability than the intermediate bed-joints; hence it is only to the former set of joints that it is necessary to apply the formule. Those formule have been Vou. IV.—No. 1. D 18 Mr. J. Bryce on the Discovery applied to the great chimney of the works of Messrs. Tennant and Company at St. Rollox, near Glasgow, which was erected from the designs of Messrs. Gordon and Hill, and is, with the exception of the spire of Strasbourg, the Great Pyramid, and the spire of St. Stephen’s at Vienna, the most lofty building in the world, being 436 feet high above the ground, and 450 feet high above the foundation ; and it has been found that the stability of that chimney is suited exactly to the maximum pressure of wind already mentioned, of 55 lbs. per square foot. March 19, 1856.—The PresipEnt in the Chair. Dr. Decimus Hodgson was elected a member. Mr. Bryce described some recent Observations on the Granite of the Island of Arran. Notice of the Discovery of a New Granite Tract in Arran. By Jamus Bryce, M.A., F.G.S. TE northern and southern halves of this celebrated island are remarkably distinct in their physical features and geological structure. The former, bounded southwards by a line running almost due east and west from Brodick bay to Iorsa water-foot, consists of a mass of peaked and rugged mountains, intersected by deep and wild glens, which diverge from a centre, and open seaward on a narrow belt of low land. The southern half consists of a rolling table-land, bleak and unpic- turesque inland, but breaking rapidly down seaward into a coast border of great romantic beauty. The general elevation of this portion is from 500 to 800 feet; and the irregular ridges which traverse it, most usually in a direction nearly east and west, do not rise above 1,100 or 1,400 feet. The northern portion, on the other hand, rises into moun- tains passing 2,000 feet, and culminates in the south summit of Goatfell, having an altitude of 2,875 feet, while many of the peaks reach a height very little less. The rocks constituting this mountain group are granite and the old slates; the latter flanked on the north and east by sand- stones and limestones of Devonian and carboniferous age. The entire southern plateau is composed of sandstone, broken through and overlaid by various trap rocks, chiefly greenstone and porphyry. The whole of this sandstone we refer to the age of the coal formation, on the ground that limestone, with true carboniferous fossils, occurs in repeated alter- nation with it, and that there is an entire absence of fossils of New-Red types; we cannot see that there is any evidence for separating a por- Of a New Granite Tract in Arran. 19 tion of it, as has hitherto been done, from the sandstones underlying, as even a rudimentary development of the New-Red system. Now, this remarkable difference in physical aspect, as well as the extraordinary variety of geological phenomena which the island exhibits, alike arise from a single peculiarity often overlooked by those who have undertaken to describe it. This consists in the abnormal position of the granite nucleus. Granite usually forms an anticlinal axis to the rocks amid which it rises; these being symmetrically disposed on opposite sides of it. But in Arran it is not so; the granite has been protruded close to the outer or eastern border of the slate rocks, so as to come almost into contact on one side with the newer sedimentary strata. So near is it, that the slate band between it and these strata, on the hill side west of Corrie, is only a few yards in thickness; and it is even probable that in some places it is in contact with the sandstone. The protrusion of so large a body of igneous rock by plutonic fires, along the line of junction of the old slates and secondary formations, and its ele- vation to so great a height in a space so limited, have produced all those varied and interesting phenomena which have given so much celebrity to Arran, and rendered it such an admirable field of study. Such being the remarkable position of the granite in the northern mountains, it is not perhaps more than was to be expected, that in its protrusion from beneath sedimentary formations already deposited before it was raised to the day, this granite should also pierce through and appear as an intrusive rock among them. Yet its occurrence in such a situation long escaped notice, and was not observed till 1837, when Mr. Ramsay, in his careful survey of the island, discovered it amid sandstones of car- boniferous age on the west side of Glen Cloy. M. Neckar, however, was the first to describe the district, which he named Ploverfield, in 1839. This granitic outburst, and the interesting attendant phenomena, are well and fully described in Mr. Ramsay’s admirable Guide, and need not now be further referred to. Our own inquiries have given a very considerable extension to the Ploverfield granite ; and in the summer of 1855, we were so fortunate as to discover another'tract of granite, overlooked by all previous observers. Driving along the lower portion of the String road towards Shiskin, with a party of friends on an excursion to King’s Cove, I noticed an extensive talus of blocks reaching from the base of a high cliff on the left, to wtihin a few hundred yards of the road. These struck meas very unlike the blocks of sandstone, which strew the surface all along on that side ; and going up to the boundary of the talus, I found that it was composed of granite blocks. I then also perceived that the cliff itself was formed of granite; and it struck me as remarkable that on a route 20 Mr. J. Bryce on the Discovery so frequented as this, the occurrence of the granite had so long remained unnoticed. On an early subsequent visit, I determined the limits of the tract to which the rock is confined. The annexed ideal section, from east to west, between Corriegills and Mauchrie water, represents the position and relations of this granite tract, as well as that of Ploverfield, the horizontal extent of the sandstone being of course much contracted :— The granite tract now to be described lies on the south side of the Shiskin road, nearly opposite the farm house of Glaister. Here the hill, whose base is skirted by the road all the way down from the “ String,” overhangs the valley of Mauchrie water in a steep cliff called Craigmore, Craig-Dhu, or The Corby’s Rock. This cliff is the outer edge of a small plateau or table land, cut off from the higher ground behind, towards Doir-nan-Each, by a deep hollow which completely isolates it. The summit is 700 to 800 feet above the valley, and is more than a quarter of a mile long, by one to one and a-half furlongs broad. It descends steeply towards Shiskin on the south-west, and slopes gradually north-east towards Moniquail. The summit and sides of this plateau are formed of fine-grained granite, very similar to that of Ploverfield. The base of the cliff towards Mauchrie water is covered by a long talus of granite blocks and smaller fragments, reaching to within 200 or 300 yards of the road, and appearing even at that dis- tance of very different aspect from fallen masses of sandstone. The granite here seems to rise either through the old red sandstone, or at the junction of this rock with the carboniferous strata. The granite is nowhere seen in situ ata low level; the talus before men- tioned obscures the rocks along the base of the hill, and the ground by the roadside, and along the valley, is deeply covered with alluvium. At one spot only could we detect any rock in situ. Immediately below the bridge, by which the road crosses a small stream, the water runs over a projecting mass, which seems to be either a serpentine, a greenstone with much felspar, or an iron-shot claystone. But at a high level on the west, south, and east sides of the plateau, the granite is seen to rise through a coarse conglomerate; and numerous contacts : | Of a New Granite Tract in Arran. 21 are observable. These are highly interesting, and clearly indicate the intrusion of the granite subsequently to the formation of the conglo- merate. The base of this conglomerate is a coarse sand, and the imbedded fragments sandstone, quartz, and granite. The base is highly indurated, and assumes a porphyritic structure; the sandstone is ren- dered crystalline, and the quartz has been fused, and often converted into a substance resembling porcellanite. The fragments of granite are of an elliptic form, less rounded than the quartz, and are exactly like the adjoining mass of granite in structure and component parts. Whence have these granite fragments been derived? From the body of fine granite among the northern mountains, or from the adjoining mass itself? Mineral structure does not enable us to determine— the two rocks are so similar. If from the former source, then we must conclude that the granite of the interior was elevated so as to be exposed to disintegrating causes, while the ‘conglomerate was forming; in which case granite fragments ought to occur abundantly in the sandstone conglomerates; but this is not found anywhere in Arran ;—a fact noticed by all observers. Even here the fragments occur only in close proximity to the granite itself. Must we not then rather suppose that pieces of the granite adjoining, when this rock was erupted in a fluid or semi-fluid state, were injected among the outer strata of the conglomerate, also fused by the contact, and so became imbedded in these strata only ? Granite, then, occurs in Arran in three disconnected tracts, and the question remains, are these of three distinct ages, or were they erupted simultaneously, so as to pierce through the three formations during one and the same period of disturbance ? The latter is by far the most probable supposition, because we find ; first, that while the granite of the nucleus, that is, of the interior mountains, everywhere pierces through, and alters the enveloping slate-band ; this slate-band, in some places where it is very narrow, /as also altered the old red sandstone in contact with it, having been itself in fusion from contact with the molten granite; and, secondly, that the actual position of the old red sandstone and carbo- niferous limestone along the Corrie shore, indicates great upheaval and disturbance by protruding masses of granite advancing in that direction from the nucleus. The entire series of sedimentary strata in Arran was therefore deposited prior to the intrusion and elevation of the granitic masses; and the Craig-Dhu and Ploverfield tracts were most probably formed simultaneously with that of the northern mountains. This question will be found discussed at greater length in the second edition of a pamphlet on The Geology of Clydesdale and the ‘Clyde Islands. 22 Mr. J. Brycy on the Low Temperatures The President made a communication illustrative of the Osteology of the Higher Apes, and exhibited various specimens, among which was the skeleton of a young Chimpanzee recently prepared. A copy of the Census of Ireland for 1851 was presented to the Library by Mr. Hastie, M.P., for which the thanks of the Society were voted. April 2, 1856.— Witt1am Murray, Esq., in the Chair. Mr. Thomas Boyd and Mr. Thomas Watson were elected members. Dr. Taylor, Andersonian University, read a paper “On the Nature and Causes of Waterspouts.”’ Dr. Taylor also exhibited a new method of Illuminating the Magic Lantern. April 16, 1856.—The PrestpEnt in the Chair. Mr. William Mackenzie was elected a member. The President announced that, in compliance with an invitation from the Council, Professor Henry D. Rogers, of Boston, United States, had consented to deliver a Lecture to the Society on the evening of the 30th instant, and that it was proposed that the meeting should be held in one of the public halls of the city—admission for the members and their friends being by ticket. The Society approved of this proposal. Mr. Bryce presented the Report of the Committee on the Low Tem- peratures of the Winter of 1854-5, Report on the Low Temperatures of the Spring Months of the Year 1855. By Jamus Brycz, M.A., F.GS. Tue Report now laid before the Society has been prepared in confor- mity with a resolution passed at the close of last session. A Committee was then appointed, “ consisting of Dr. Thomas Anderson, Professor of Chemistry ; Mr. James Bryce, High School; Mr. Thomas R. Gardner, optician; Mr. Robert Hart, Cessnock Park, Govan; and Mr. James King, Windsor Terrace—Mr. Bryce, Convener’’—with instructions “ to make inquiries as widely as possible respecting the low temperatures of the spring months of the present year, and report to the Society next session.’”” The Committee soon after entered on the inquiry. In reply to a circular distributed as widely as possible during the summer, returns were in due course received from a considerable number of places, widely separated over the country. On these, and the facts collected by the members of the Committee, the present Report is founded. The author Of the Spring Months of the Year 1855. 23 desires to acknowledge his special obligations to Mr. Gardner and Mr. Hart, for the valuable aid which they have rendered. Much information was also obtained by the kind co-operation of Mr. Clark of the Botanic Garden. It is matter of regret that the Report now presented cannot lay claim to much scientific value. The instruments whose indications are given were not compared with one another, or with any common standard, so as to give precisely correspondent results. When the inquiry was under- taken, no combined system of observations in regard to Scottish mete- orology had yet been instituted ; and the Committee had, therefore, no choice but to make use of such information as they could draw from the registers of isolated observers, employing instruments, probably good enough in their construction, but without that value in their indications which is given by inter-comparison, and the application of a uniform plan of reduction. Happily, however, such a combined system has now been established ; and any future Report having reference to years sub- sequent to the present will possess a true scientific value. In September ™ last, at the meeting of the British Association in this city, a Meteoro- logical Society for Scotland was organized ; in connection with which, and at suitably selected stations, there will soon be a great many observers recording their observations simultaneously at the critical hours, by means of instruments of the best construction, and previously compared with a standard. The discussion and comparison of these, under the able superintendence of Mr. Keith Johnston and Dr. Stark, will, doubtless, in a few years, make us acquainted with many important laws; while the publication, from time to time, of the continuous and combined records of all the phenomena, will render unnecessary such an inquiry as that entered upon by your Committee. This Report, indeed, can only be regarded as a feeble attempt to supply the want of such a society—to foreshadow the advantages which will result from its labours, and to fix a sort of rudely measured approximate base, with which to compare inquiries and observations in years to come. The spring months of 1855 were distinguished from those of many preceding years by a continued low temperature. During the month of December, 1854, and the early part of January following, the weather was mild and open, with slight frost on a few days only, and winds varying, at Glasgow, through the quadrant, from S.W. to N.W. Here, on the 12th January, the wind went about E., and a slight frost was first experienced on the night of the 12th-13th. The change of weather was almost simultaneous at the other stations from which we have returns, and which range from Stornoway, the Orkneys, Elgin, and Aberdeen, to Kirkcudbright. Frost, at first slight, set in between the 10th and 14th 24 Mr. J. Bryce on the Low Temperatures January, and continued of extreme severity till the end of February. From that date till the 6th of April, the temperatures were somewhat higher, but still very much lower than usual in the spring months. Partial thaws, with slight elevation of temperature, and very little rain occurred on the 19th and 20th January; on the 3d, 4th, 5th, and 24th February ; and again on the Ist, 2d, 12th, and 13th March. With these exceptions, at Glasgow, and most of the other stations, there was continuous frost, with occasional slight snow-falls, throughout the period. The details will be seen in the accompanying tables. These do not, however, give the complete registers at all the stations. Our inquiries having been chiefly directed to the subject of temperature, complete registers were not asked for; and besides, their insertion would have made the tables very cumbrous. For the returns received we have to express our grateful thanks to the following gentlemen :—Alexander Smollett, Esq., M.P., Cameron House, near Bonhill, Dumbarton; Sir James Matheson, Bart., M.P., Stornoway Castle, and the Rev. James Gunn, minister of Cross, Stornoway ; E. J. Bedford, Esq., R.N., Manor House, Oban; J. W. Melville, Esq., Mount Melville, and Alexander Watson Wemyss, Esq., Denbrae House, by St. Andrews ; J. B. Neilson, Esq., Queen’s Hill; Stewarton, Kirkcudbright; William Miller, Esq., Eastwood Hill, near Mearns, county of Renfrew; Professor Nichol, College Observatory, Queenston, Glasgow; Professor Ferguson, King’s College, Aberdeen; Professor C. Piazzi Smyth, Edinburgh; Mr. George Berry, Dalvey Gardens, Morayshire; Mr. Clark, Botanic Garden, Glasgow ; Professor Dickie, Queen’s College, Belfast. Of the Committee, Mr. Robert Hart, Cessnock Park, Govan; Mr. Thomas R. Gardner, Ibroxholm, two miles west of Glasgow; and the author of this Report, have furnished their registers. That of the author is kept on the north-west boundary of the city, yet exposed to influences tending to elevate the temperature, as will be seen by the higher read- ings of the thermometer. The temperatures at Sandwick, Orkney, are taken from the well known register, published each month, for many years past, in Zhe Philosophical Magazine and Journal of Science (vol. ix., 4th Series, January to June, 1855); those at Edinburgh and Orton Hall, near Peterborough, Yorkshire, from Zhe Scottish Gardener and Journal of Horticulture (vol. iv., 1855),—the registers at these places being kept by Mr. Macnab of the Botanic Garden, and Mr. John Reid. One unavoidable defect of the tabulated results has been already alluded to—the want, namely, of previous inter-comparison of the instru- ments. Another arises from the circumstance that some of the columns give the maxima and minima temperatures, and others those at the hours now usually regarded as the mean howrs. The numbers in these Of the Spring Months of the Year 1855. 25 columns are, therefore, only comparable in a very general way ; they do, however, indicate to us that the lowest morning and evening tempera- tures occurred on the days of minima at most of the stations, and that the changes during the period were in a great measure correspondent. Setting in on various days between the 9th and 14th January, the frost was fully established at all the stations by the middle of the month, and till the end of February the weather continued of extreme severity. The whole of March and the first week of April exhibited somewhat higher, but still very low general temperatures; and it was not till the 6th April that genial weather was experienced, with rain and westerly breezes. The period, therefore, comprised from eighty to eighty-five days, one of very unusual continuance, in these islands, of tem- peratures so low and widely experienced. It appears from all the returns, on comparing the indications at high and low adjoining stations, that the cold was more intense at the lower station. The minima, as is usual in such cases, occurred towards the close of the period of greatest severity of the frost, that is, towards the end of February. During the entire period, the wind remained almost constantly in the northern semicircle of the horizon, ranging through 135° between E. and N.W. Stornoway alone presents an exception, especially in January, the wind being from the south quarter during twenty-five days, and from the north during the last four days only. The wind was almost always so light that it was often difficult to know the exact point from which it proceeded. The barometric column was at its maximum at the setting in of the frost, at all the stations. The heights are given in the fol- lowing table :— BLORNOWBY} sic onaseadedescdee 80-45 | 30°45 30°45 30°40 30°45 BISTILWICK recs cocccoseocscneos ee 30:58 30-54 tie Fee EDU etcesccletecsscssceace = 380-22 BIO nine sasesebenn ans Son 30-543 The minimum at Glasgow was 29°714, and occurred on the 25th February, with snow-fall and wind at N.E. At the other stations the minima were nearly correspondent, being towards the close of the month. The heights corresponding to the lowest temperature on Feb. 17th were 30004 and 29°964, at Glasgow. At the other stations the height of the mercury at the times of lowest temperatures was also intermediate between the maximum and minimum, as will be seen by reference to the tables. In no case does the minimum temperature Vou. IV.—No. 1. E 26 Mr. J. Brycx on the Low Temperatures correspond with a maximum of pressure, or vice versd. We have no data, however, in our returns, for separating the effects of the dry air and aqueous vapour. In the following table the minima temperatures are brought together for the sake of easier comparison. Those temperatures only are given which reach 20° F., or under. The elevation of several of the stations above the sea level is annexed :— Days— (10) 12/13/14| 15| 16| 17/18/19 20) 21\22| 23) ,1 S00, Feet. Glasgow-—Bot.'Gardens| 2. |occ0 (sis!) ccs |) Fo! | weet] ece | ozs |! ces’) eect] com inate freeman ne Observatory,..........4. sésilligselcssel] seal Be | LOST SBI) seeil ce call lsc}: adel vesed amen ere GOVE G arcaesvesecuenc's Sea fiese LO a eO NLA D le SOY | 7 19° Di s.0i|lencilisce| te ommees Abroxbolii;s..<.. cesses Wee | sacl eat eeelebon)) oe iP OneOlatan 20 16) 14/15] 36 Lansdn. Cres.,9 A.M.,..|....| ..| 20} 20) 20 | 14 | 11]... ...|...| 19) 15} 42.) 85 Eastwood-hill, ......... Pees) cicnin teeny) twcetlinraman dl RO | UWL! acasel cnc || seteur| (MMIC ere ete LESE RC Bonhill,..... Spndsieeataedes gest] exsi|icece | Sel ete. | Tse Le sae leet eke etter eee eee Wit is6 2s | scisue as SE Feee | rave | BGM AIO: | aeuslt soe lbs wallncscl densi bale pee RSLOTUG WHY; swee ces owas ing eaeifisoa|\ eco til wecal LZ. (vecdily oon | 09.1) 20\| UO) aol OD HAMUWIGES Oey E-Wajsrego|iiens |Vennll ean'| vezi 20 "| ren [eee | /coul| sse\|| son'| ess] 20) Meal mee Dal were isis. spaeeosns abei| ives dealli ect enc OHA koe litsce| Mu'oiesl "eisietl neces b acead] eaen mm Aberdeen —— Kane's Cols.) csilusoes|iess)| e+e |i ponnt L220 |\:d0s || vaes,|' ss) ’oe)|| coat] tonal ieee MOU MMarischial’..) sci sce [rece | eee | cred eoed” [bse [cee | cce'l eco | neat] eed eee St. Andrews,..........4.. j eee | coe] oo] wee] 18 | 17 | oe] 17] 00 | woe] ace] eee! one [328 Edinburgh,......s00...008 [eseetlpeces(BbS| DAYS Bol AO) oo) L5:|) coi lb) ceil ined een aE? Stewarton,..........000008 ses |vese [ose sca lta | Cor) LO) ce. | enol!) tox jeenen Oemel| ieee ene Ontony eiceteeceet ek ce ack 1322 G4 HO)) 1B 4) VE 2 soe] ei Be Si Oh eb eee BOSEON esc sscsenasccscssnen pacer | uaosl Ciaiea| vaeunl Vos call Mben'es (oearenl|| ey] se sadly we. mate i nd DU eT CHISWICK sav evecssssences Paes | OWL OM oS S207) 8) LO eet | etateg eee Belfast}: tire .dcccvstes vee Jere] ove | eee] 18] 13 | 19 | 20) 17] 0.0]. ] oe] oe ve 50 At Orton, on February 1st and 27th, the temperature was 4°; on the 5th, 1°; on the 9th, 6°; on the 12th, 2°; on the 26th and 28th, O°. Here, therefore, and at Chiswick, near London, the temperatures were lower than at any other of the stations, except those in Aberdeen and Moray shires. The yearly volume, issued from the Radcliffe Observatory by Mr. Manuel J. Johnson, and the Records of the Meteorological Society of England, show that at Oxford and various stations through- out England, the temperatures of the period were considerably below the mean of twenty-five years. The minima of February at Oxford were 7°5 and 9°5 on the 16th and 17th, exactly coinciding with the epochs of lowest temperature at almost all our stations—minimum at Huggate, Yorkshire, 13° on 18th February ; at Torquay, 27°, day not named. The prevailing low temperatures over so wide an area are very remarkable, and probably much lower than any experienced for even a much longer period than twenty-five years. There was more or less snow at all the stations during the month of February ; and with the Of the Spring Months of the Year 1855. 27 trifling exceptions of the partial thaws already mentioned, the frost was persistent. About Glasgow, as well as at most of the stations, the depth of snow was inconsiderable—in high and in sheltered situations, about three to four inches; but completely wanting in those having southern exposure. Severe drifts occurred in Orkney, Moray, and Aberdeen shires; and at Orton and in Moray the snow for some weeks was nine inches deep. The mean temperature of the month at Chiswick was 28°-01; mean of twenty-nine years previous, 39°'07 ; mean of February, 1854, 37°67. Regarding this month the Rev. C. Clouston of Sand- wick has the following remarks :— “Mean temperature of this month, . : : - - . 31°64 Mean temperature of February for twenty-eight years previous, 38 -24 Mean temperature of February, 1854, . ; 5 : OO oe Average quantity of rain in February for fourteen years previous, 3 *39 Quantity this month, . * ° : ci : A ~ 132 The mean temperature of this month is lower than that of any month for the last twenty-eight years, except February, 1838, when it was 31°31, and when there was snow during all the month, and for three weeks previously. This month it lay from the 11th till the last day ; and the drift on the 23d and 24th formed high wreaths in many places, rendering the roads impassable to vehicles.’”” We believe, however, that the severe weather in spring, 1838, here alluded to, was by no means so, general as that of 1855. In 1838, however, Loch Lomond was com- pletely frozen over, as on the 16th February, 1855. On the 17th it was visited by large parties from Glasgow, to enjoy and to witness the amusements of skating and curling upon this “ Queen of Scottish Lakes.”’ On the authority of Mr. Miller of Eastwood, we can state that on one occasion, prior to 1838, and also within this century, Loch Lomond was completely frozen and rendered passable. This was pro- bably in the winter of 1813-14. _ The mean temperature of March at Chiswick was 37°61; mean of March for the last twenty-nine years, 42°24; mean of March, 1854, 42°54. Average amount of rain in March, 1:33 inch.: At Sandwick, the mean of this month was 36°61; mean for twenty-eight years, 40°53 ; mean temperature of March, 1854, 45°-14—the highest during the whole period of twenty-eight years. The mean temperatures of March, 1837 and 1839, were 36°54 and 36°33 respectively, almost the same as that of March, 1855. The temperatures of April and May, 1855, were also from 3° to 4° below the means for twenty-eight years previous. Average quantity of rain for fourteen years, 2°52 inches.— Generally, as regards all the elements, the Oban, Stornoway, and Orkney stations, manifest the effects of oceanic influences, and the 28 Mr. J. Bryce on the Low Temperatures characters of a more insular climate, than is found at any of the others. The fall of rain, as already remarked, was very inconsiderable during the period, owing to the steadiness of the frosty weather. The returns do not embrace this element except from a few of the stations; and these are brought together in the following Table. For the sake of comparison, we insert the amounts at Sandwick, Boston, and Chiswick, and add also the month of May. The melted snow is included in the Govan, Ibroxholm, and, we presume, in the other returns also :— TABLE OF RAIN-FALL. 1855. Govan. | Iproxu. EAstwp.| BONHL. STORNY.| SANDE. Bossche Tariana. eae 0-73 | 0-75 | 0:40 | 150 | 3:00 | 3:26 | 0-43 | o-10 February,.....sssecccres 0°68 | 0°60 | 0°05 | 1°80 | 1:50 | 1:32 | 2°18 | 1°35 DMEBDCH Sccccescusssencnce 1:74 | 1:54 | 2°20 ae ase 3°58 | 1°35 | 1°75 EUPINID wslaeahincts'sy ot cnpp dss 1:38.) 2:26) 1°10 woe wae 2°89 | 0°23 | 0:26 Ie ecotcesyes eanmienuscis 1-60 | 1°48 | 1:60 awe ase 1:38 | 1:26 | 1°94 | 6°13 | 5:63 | 5:35 “ee an 12°43 | 545 | 5:40 Regarding the rain-fall at Eastwood-hill, Mr. Miller observes, that it is “not only much less than at Glasgow, but much less than in any other part of Scotland that he has heard of. In the corresponding months of 1854, the fall was 12°20 inches, or abouttwo and a-half times as much.” The following Table shows the monthly average of these several months for a long series of years, and is inserted here for the sake of comparison with the foregoing Table, as showing the superior dryness of the early part of the year 1855 :— TABLE OF AVERAGE RAIN-FALLS. JANUARY. | FEBRUARY. Maxcu. APRIL. May. Glasgow—twelve years, .......... 3°75 3-04 1:45 1:53 2:02 Sandwick—fourteen years,....... 4°38 3°39 2°52 1:83 1:68 Boston—nine years,......ssscecees 1:53 1:02 1:31 1-43 1:20 Chiswick—twenty-nine years,...| 1°74 1:54 1:33 1°59 1:85 Very few observations on which any dependence can be placed have been received in regard to the penetration of the frost of 1855 down- wards into the soil. It was certainly considerable in many places; for in ground with a northerly aspect in the neighbourhood of Glasgow, ten days to a fortnight elapsed after the breaking up of the frost on the 6th of April, before the plough or spade could be employed to open Of the Spring Months of the Year 1855. 29 up the soil; and farming operations were in consequence much delayed. With the arrival, however, of the genial weather, vegetation advanced with amazing rapidity ; and the hay and other crops were very little, if at all, later than usual. Neither was the long drought followed by any unusual fall of rain. The penetration of the frost would depend much on the nature of the soil. The following estimate has been formed by a skilful farmer and highly intelligent man in the Lewis, a friend of the Rev. James Gunn, whose kindness we have already acknowledged, and by whom this infor- mation also is sent to us :— 1. Into moss on which heath grows, the frost penetrated - 6 inches. 2. Moss on which no heath grows, : 5 i 3. Arable land in field or garden, f : ‘ 5 -12 — In comparison to these, the frost of 1856 did not penetrate above one-fourth the depth. Mr. Miller of Eastwood makes the same esti- mate for arable land about Glasgow, viz., 12 inches. As bearing on this point, Professor C. Piazzi Smyth has been so good as to furnish us with a copy of the register of the deep soil thermo- meters kept by him, and examined and entered weekly. We subjoin (see Table) the record of only two of these, ¢, and ¢;, respectively at three feet and one-tenth of a foot in the soil—the others at six, twelve, and twenty- four feet being too deep for our purpose. Of the latter, Professor Smyth says, in a letter to us on September 8, 1855—“ They are still suffering under last winter’s cold, so slowly does the wave of annual temperature travel downward through the soil.” The indications given in the appended Tabie, drawn up from data kindly furnished by Professor C. P. Smyth, correspond with those of the other Tables. The thermometer ¢;, one-tenth of an inch under the surface, read lowest on the 19th February ; ¢, at three feet, on the 26th, or ten days after; and the readings generally are the lowest at or soon after the time of greatest cold,—a considerable rise taking place between the 2d and 9th of April—the 6th of that month, as already remarked, having been the day on which the frost finally broke up. The monthly means are given for four months of 1855 and the four previous years, in order to place the contrasts of temperature in a more striking light. The means for 1851-4 are taken from the Tables given in the last published or eleventh volume of the Zdinburgh Astronomical Observa- tions. ‘These Tables embrace the entire series of observations of the Earth-thermometers since 1838, carefully reduced, and accompanied by descriptive and explanatory matter from the pen of Professor Forbes, and a brief statement of some of the results by Her Majesty’s Astrono- mer for Scotland. A full exposition of the significancy of these Tables, 30 Mr. J. Bryce on the Low Temperatures by either of the distinguished physicists above mentioned, would be a great boon to the scientific world. The influence of this severe season on trees and shrubs is remarkable. The following particulars have been kindly furnished by Professor Dickie of Queen’s College, Belfast, being extracted from a ea by him on the subject, now passing through the press :— In inland situations in Aberdeenshire, where there was a considerable covering of snow in February, all the young plants of arawcaria imbri- cata were uninjured, except such as had branches protruding above the snow. Near the coast line, the effects on whin and broom were most conspicuous, for two reasons—the plants attain large size, and the cover- ing of snow is less. Bushy plants, browsed by cattle, were uninjured, owing to the covering of snow. The effects were more conspicuous on these than on any other wild plants. They were generally killed in ex- posed places nearly to the ground. In the summer, new shoots were pushed out from below. Species of rosa, rubus, and salix, growing along with them, were uninjured. Sections of stems of whin and broom killed by the frost were examined under the microscope, but no change in the tissues could be detected. The only difference between them and sec- tions of living ones was the existence of brown stains near the duets ; but this difference was not constant. There seems no way of account- ing for the different effect of the frost, but by some original difference in constitution among plants. A great many exotic trees, and shrubs, were either materially injured or totally destroyed; but it would be rash to say that this indicates their inability to resist low tempera- tures under any circumstances. In every instance it was observed that the destruction was greater in low than in high situations, and this even in the same garden. This was seen in places not more than 100 yards apart, and differing only twenty feet in elevation. Dr. Dickie, rightly, we think, attributes this to accumulation of the heavier, colder, and damper air in such localities. After giving many striking examples from Aberdeenshire, the following is recorded from Belfast. The loss there was less, partly because the minimum temperature was greater than in Aberdeenshire, exceeding it by 14° to 17° F., and partly from the site of the garden being high and well drained. Among twenty plants destroyed, there were nine species of the pine tribe, one heath, and two other shrubs, which, in a locality three miles north-east, one mile from the sea, and 450 feet above its level, stood wholly uninjured. The Belfast garden varies from 50 to 75 feet above mean tide level. Dr. Dickie gives full details in this important paper regarding the plants destroyed in Aberdeenshire and at Belfast; and calls attention to the great value of observations and records on this subject, as affecting the Of the Spring Months of the Year 1855. 31 naturalization of certain plants in our climate, and the knowledge which in a few years they would give us regarding the plants which might be expected to survive such changes of temperature in particular districts. Much ultimate disappointment, both to the buyer and seller of exotics, would thus be avoided.* On the same subject, the following interesting particulars have been kindly furnished by Mr. Clark of the Glasgow Botanic Garden :— “The following plants were destroyed in our garden by the severe frost of the spring of 1855 :— “ Thirty plants of Cupressus torulosus, which had stood out in the open border for some years. ‘This fine coniferous plant was introduced from Nepél in 1824, and has always been considered hardy. “ Cupressus funebris. This tree having been introduced from China in 1849, the stems had not attained the same degree of strength: though destroyed in Glasgow, it has survived in several other places. “ Prunus sinensis. “Pinus microphylla and P. montezuma. Neither of these had been more than two years planted, and they were not sufficiently established to enable them to resist a degree of cold which they might have stood otherwise ; microphylla has survived in many places. “ Libocedrus chilensis, destroyed also in most places. It was intro- duced from Chili in 1849. ** Many Portugal Laurels and Common Bays. In every instance where these were killed, they stood either under the shade of other tall trees, or in low damp situations, where the young wood of the previous year had not been sufficiently ripened, or exposed to the same amount of light and air as those standing in open situations.’ “Tt was pleasing to observe,” continues Mr. Clark, “that many exotics, not considered hardy, survived this most trying season (1855). Having been anxious to test the Rhododendrons of Dr. J. D. Hooker’s Himalayan collection, I had some of them, previously kept in a cold frame, removed, before the winter set in, to an exposed situation. The following stood out without any protection and survived:—R. ciliatum and ciliatum-rosea, R. campylocarpum, R. lepidotum, niveum, R. glau- ° cum, R. Wallichii. Also, R. barbatum safe, planted out two years previously. It is from northern India. In 1852 a plant of R. cinna- momea, a magnificent variety, introduced from Nepdl in 1820, was planted out, having been previously kept in the usual way in a green- house or conservatory, and sustained the frost uninjured. Cedrus deo- dara and Araucaria imbricata, quite safe, being in high dry situations. * This paper has since been published, and will be found in The Proceedings of the Botan. Soc. of Edin.—Scot. Gardener, July, 1855. 32 Mr. J. Brice on the Low Temperatures The latter, however, does not thrive well in the neighbourhood of Glasgow, on account of the dampness and cold of the subsoil overlying our coal formation.” We have examined many scientific journals and transactions of learned Societies, in the hope of finding records of similar seasons of severity, with which to institute a comparison, and of perhaps catching some glimpse of a law of periodicity, or a return of such weather in cycles. But we have met with nothing worthy of bringing before the Society, excepting a few brief notices. One of these is from the pen of the celebrated Dr. Alexander Wilson, Professor of Astronomy in Glasgow University, whose theory of the solar spots, and the nature of the photosphere of the sun, has been generally adopted by astrono- mers. It is found in a short paper in Zhe Philosophical Transactions for 1771, and refers to two days of January, 1768. On the morning of Sunday, the 38d January, 1768, awaking early, he was surprised to find himself extremely cold in bed, and on putting out his arm to a table near his bed for a glass of water which stood there, and bringing it to his mouth, he found it was a mass of ice. Struck with an occurrence so extremely uncommon, he got up and dressed, and forthwith proceeded, with the aid of his son, to make various experiments, which he describes. We need here only give his record of the state of the thermometer on the two days mentioned. These are probably the lowest temperatures ever recorded as having occurred at Glasgow. The Observatory, where he resided, was in the eastern part of the College Park. The thermometer was properly protected. Jan. 83,1768. 10 h.am.,...... 5° Jan. 3, 1768. 9 h. p.m.,.... 2° 93 1 Jan. 4, FPS, I atbalprey ede loathe Tiel) I Hebegurten fe lee Mele Te tral The record extends no farther ; and there seems to have been a sudden change of weather. On the forenoon of the 3d he laid a thermometer on the snow, in a shady place, and found that it fell in a very short time from 6° to —2°; and from this he inferred that before he began his obser- Of the Spring Months of the Year 1855. 33 vations there had been greater degrees of cold than those he had noticed. The depression was, no doubt, due to the increased radiation. This severe cold does not appear to have been general; for I find the great- est recorded cold at Liverpool, for January of that year, was 29° F. at noon ; and at Middlewich, in Cheshire, at 8 a.m., 23° F. In a paper in Zhe Manchester Memoirs, vol. iv., 1793-6, Dr. Thomas Garnet brings together observations made at various places in England, and at Dumfries and Kirkmichael, in Scotland, for the years from 1768 to 1795. The lowest recorded temperatures of the period occurred at Chatham, in the last week of January, 1776. They range from 28° F. to —3}° F.; the latter being on the 31st, at the hours of 6, 7, and 8 a.m. In this paper the negative values are expressed by writing the figures below a zero. The winters of 1784 and 1786 seem also to have been characterized by low temperatures ; also those of 1812-13, and 1813-14. At Dumfries, on Jan. 25, 1784, the thermometer stood at 8° F. early in the morning, and on the four previous days had ranged from 11° to 14°. The late John Templeton of Cranmore, near Belfast, a distinguished botanist, published in The Belfast Magazine for 1814 a paper, giving a list of the plants destroyed in the severe winter of 1813-14. The frost began in Nov., and on Dec. 29 the thermometer fell to 7° F. The registers discussed by Mr. Glaisher in two papers in Zhe Phil. Trans.(1849, part ii., and 1850, part ii.), run through seventy-nine years, and embrace 200,000 observations, made at Somerset House, Greenwich, Epping, and Lyndon in Rutlandshire. From these he has deduced, with that skill and sagacity which distinguish all his labours in this field, an approach to periodicity in the mean annual temperatures at Greenwich. The results are stated in Mr. Drew’s admirable little work on Meteorology; where will also be found a plate giving the projected curve of temperature. So much as relates to our present purpose we give in Mr. Drew’s words, p. 84:—“ An inspection of the form assumed by this curve shows that, beginning with 1771, the years become gradually warmer till 1779, when the temperature in like man- ner declined, and a batch of cold years occurs, of which 1784 was the coldest. The heat then increased, but not in so great a degree, till 1794, when the extreme cold of that cycle, not so severe as before, was reached gradually in five years from that time. In periods varying from nine to fifteen years, throughout the whole series, we find the cycle of hot and cold years repeated.”” This is, we believe, the only attempt yet made in this country to grasp such a law of periodicity. Mr. Glaisher has also deduced a formula by which the mean annual temperature of any place may be found from that of Greenwich. Wor, LV.—Noz I. FE Mr. J. 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Thermom. || Thermom, | 24 Daa, | 29-700 29-750 29 690 29°636 5| 29°638 29-800 29°866 30°100 30°014 29°838 29°726 29°675 29-788 29°664 29-700 29°672 29-654 29°682 29°820 29°870 29°660 Barometer. Oram. | | 29-720) 40 | 39 29-732 29-640 | 29-650 | 29-664 29-770 30-000 30-190 29-910 29-758 | 29°700 29-700 29:700 29-675 29'656 | 29-660 29-670 29:680 29-860 29-778, 29-652 29-600) 29-650 | 29-652) 29-652 29-648) 29°650 29:676| 29°674 29°662) 29-666 /29°800 29-950 30-200) 30-350 35:5] 30°470 30-485 26 || 30°500| 30-506 25 || 30-458) 30-400) 28 Giascow—LaNSDOWNE CRESCENT. Thermom. | 39 ane Cs o zw tet 2 ps is] 28 i. Lae 9 am.!9 P.M. AM. 9 S.W. BAA nin AAA ane Wind. o " wana» gx 4 “mM a n zg HAnoMdmtint 4am" #3: slolob ae Shit Sum “ene 3m wennn ASS ote BP bs yw Bae B ms aan Me a> zs Di pyaa rane 5 nae 1855. | 41:52 | 36-24|| 42-54 THERMOMETERS. ; 3 Feet. | 01 Ft. ir | 1855 PDE OS Baas arr | Jan. 1 | 41-67! 39-6 | 44-1 | 8 | 42:89 | 42:6 | 48-0 |} 15 | 42-34 | 34:0 | 34-9 22 | 40-95 | 34:4 | 35-9 29 | 39-76 | 30-6 | 32-1 / | Feb. 5 | 38°71 | 33:3] 35-1 || ) 12 | 38:33 | 30-5 | 33-2 || 37-74 19 | 37:29 | 29-1 | 34-4 || | 26 | 36°63 | 30-4 | 36-1 | Mar. 5 | 37-16 | 366 | 46-0 | 12 | 87:80 | 34-4 | 40-7 37°76 | | =—19 | 38-07 | 35:5 | 47-0 || ! | 26 | 38:02 34-4 | 44:9 | Apr. 2 | 388-44/ 36:6 | 48-2 |j ) 9 | 39°82 | 42°6 | 53-3 16 | 40°89 | 45-9 55-8 || 41-07 23 | 42:96 | 45:7 | 64:0 | 30 47:3 | 63-1 | 43°95 MonTHLY MEAans. 1351. | ] ts || te | | 30°82 || 41-76 | 35°22 |, 41°45 | 1852. | 1853, ts | ta 41:96 41-47) 41-50 38°68 39-96 | 40-93 | 38-77 | | / } } Mr. J. Bryce on the Low Temperatures of the Spring, &e. > E p 4A3 natn: nan = So nnn aA PES ES pbs iz ozz a.m., the direct solar radiation was 180°. So rapidly, indeed, does the direct radiation or heating power of the rays increase with the height, that the cochineal insect is killed by the heat at 3,000 ft., though thriving well and yielding a rich produce at Oratava, on the sea level, at the base of the Peak. The chemical power of the rays also increases greatly with the height, as shown by Saussure before photography was known. Prof. Smyth found the difference remarkable on his photographie pictures ; they were more easily taken, and much more intense at great altitudes. The chemical rays are more dispersed and disturbed by the dense atmo- sphere below, than the luminous ones. He conjectures that at fifty miles up, usually regarded as the height of the atmosphere, the tempera- ture of shade would be —50° F., while the effect of direct sunlight would be increased hundreds of degrees. The existence of perpetual snow, then, must be independent of radiation, and due to the temperature of the air and the non-conducting power of ice. The decrease of tempera- ture with latitude is due to a different cause, namely, the sun’s diminished altitude. The heating power of a beam which acts per- pendicularly on a surface equal in area to a section of the beam, if acting obliquely is spread over a surface greater in the ratio of the sine of the obliquity to radius. The heating power on a horizontal surface is given, according to Sir John Herschel, by the expression ‘01093 cos. 2, where z is the zenith distance of the sun,—independently, of course, of Sciences of Meteorology and Terrestrial Magnetism. 167 the physical character of the surface. The heating power is thus greatly diminished at low altitudes of the sun. The changes of temperature have thus a certain general dependence on altitude, and on latitude ; but no law of decrease has yet been established in either direction—the complex elements, indeed, seem to throw great obstacles in the way of our ever determining such a law,—we shall therefore state a few of the best ascertained facts, in order to give a general notion of the subject. And, first, as regards the distribution of heat in latitude, the recent corrected isothermals of Dové show that the decrease is extremely different under different meridians; the decrease, as we advance from the equator, is least near this line, and becomes progressively greater to about lat. 45°; the temperature of the equator is 79°°8 F., but the warmest parallel does not coincide with the equator; it is that of about 10° N., and here May is the warmest month. At the equator the maxima temperatures fall in April and November, the minima in July and December. The mean temperature of the pole is 2°:2 F. ; in summer (July), 3°°6; in winter (January), —26°-6. In July the equator is 48° warmer than the pole; in January, 106° warmer. From latitude 40° up to the pole, July is the warmest month; in latitude 30° August is the warmest; in latitude 20° the two are equal. From latitude 60° to the pole the temperature may be found with great exactness by the following empirical formula :— t =-+ 3°°65 + 105°75 cos’ x x being the latitude, and ¢ the mean temperature of the year in that latitude. . . . From the equator to latitude 40° S. the temperature of the southern hemisphere is lower than that of the northern. But Dové thinks that this may not be so in the higher latitudes. East of the meridian of Ferro the decrease of the temperature of January in going north is given, between lat. 0° and 30°, by the formula— t = 82° + 47°5 cos 2 a, and in the western hemisphere, between lat. 0° and 40°, by the formula— t = 32° + 46°15 cos (2x2 — 7°); for both hemispheres for north latitudes, both high and low, t =— 23°1 + 102°4 cos’ x and still nearer the truth for low latitudes— t = — 22° + 101°25 cos’ x. For the eastern half of the southern hemisphere, the formula t = 20°8 + 59° cos’ (a — 5°), 168 Mr. J. Bryce on the Recent Progress of the will do very well for January. To show how completely other causes modify those depending on latitude merely, we may mention, as strik- ing facts, that the isothermal of 23° F. in April passes from latitude 52° in Canada across Labrador, up to latitude 75° or 80° in Green- land, bends E. to touch Spitzbergen in latitude 80°, and then descends steeply to the mouth of the White Sea in latitude 68°. In January we may pass from the Shetland Islands to the English Channel with- out changing the temperature; while, if we pass W. of this isothermal, we have a higher temperature, as in Cornwall and Ireland. The line of 32° F. passes from Philadelphia (latitude 40°) across Newfoundland, touches the S. of Iceland, and reaches the polar circle (latitude 663°) on the meridian of Brussels; it then descends perpendicularly, and crosses central Europe to the Balkan mountains; thence it runs due E. to the east of China. These remarkable inflections point to the action of other causes than the sun’s declination merely, and on the west of Europe are now universally ascribed to the Gulf Stream, that immense body of tepid water which passes to the coasts of France, Britain, and Norway, from the great heated and constantly overflowing caldron, the Mexican Gulf. Other ocean currents, the varying floor of the atmosphere, and the diffusion of vapour by the winds are also modify- ing causes. Some exceptional phenomena are yet waiting for explana- tion. The existence of a “ polar basin,” that is, an unfrozen sea about the pole, is strongly suspected. A party of Kane’s expedition remained for thirty hours on lofty cliffs on the west coast of Greenland, in latitude 813°, and looked down upon an open sea, with its waves “trooping tumultuously from the pole” under a N.E. breeze, and yet no drift ice was to be seen. Farther south the cold was the most fearful ever encountered. The mercury froze at about —68° F., and when solid, indicated by its contraction still lower, but undetermined degrees of cold. What a grand object it would be to solve this great mystery, and reach the pole upon an open summer sea from the N.W. point of Greenland.* The researches of Dové have led him to abandon the old notion of Brewster, Kaémtz, Mahlmann, and Berghaus, that two poles of maxi- mum cold existed in the northern hemisphere. He does not recognize their existence at all, and even goes so far as to say that “ Brewster, by confounding the polar with the equatorial map-projection, was led to suppose that the isothermals of lowest temperature curved in separate branches round two such poles of maximum cold.’ In North America * Dr. Rink of Greenland, in a paper lately laid before the Royal Geographical Society, endeavours to show that these observations of Kane’s companions are not trustworthy, and doubts the existence of such open water as they have described. —(April 24, 1858.) Sciences of Meteorology and Terrestrial Magnetism. 169 grain will scarcely ripen, except in sheltered spots, beyond latitude 50° ; here the cold winds are from the N.W., and trees cease before latitude 60° is reached. In Asia the warm and moist currents brought up from the south over Central Asia by the floor or basis being extremely heated in summer, “cause an arboreal vegetation to flourish up to latitude 72° over ground perpetually frozen at the depth of a few feet.’ Here the cold winds are from the N.E. (10.) It has been long the practice among physicists to assume, on the ground of loosely collected records of mountain ascents, that there is a direct simple ratio between height and temperature in the atmosphere as we ascend. Recent observations seem to show that all these are incorrect, but no simple ratio has yet been grasped. It would appear that Laplace’s law, though not exact, gives a less error when cempared with balloon ascents than any other,—namely, that there is ~ a uniform fall of temperature when we ascend through heights increas- ing in an arithmetical series. The balloon ascents in 1852 at Kew, under Mr. Welsh’s care, to heights of 19,510 feet, 19,100 feet, 12,640 feet, and 22,930 feet, were conducted with the greatest nicety as to instrumental contrivances. The temperatures were carefully observed in correspondence with the heights of the quicksilver in the barometer ; but it was from these barometric indications that the height was deter- mined, according to Laplace’s formula, in which his hypothesis of a decrease in temperature is an element. Hence these temperatures, as observed by Mr. Welsh, are exposed to doubt; because, if Laplace’s law is incorrect, the heights are incorrect. The perfection of observation of course would be that the heights of the balloons should be determined by trigonometry, not by the barometer; then we should have the observed temperatures freed from every source of error, and perhaps some new exact law of decrease might be deduced. It is not easy to see, however, in what way this is to be attained. In the balloon ascents of Mr. Welsh, strata of cloud were frequently passed through; the temperature, before decreasing, then rose; after passing some distance above the clouds the decrease was resumed, but the rate of decrease was greater below the stratum than above it. The disturbing causes of this character being allowed for, Mr. Welsh considers that the observations countenance no other hypothesis of decrease than that “ this decre- ment is uniform with the height.” The average of all the ascents gives a rate of 1° F. for 386 feet. The fall in ascending along the surface, as up a mountain side, is much more rapid (see Article 14). In some of the ascents, clouds, in the form of a cirrous haze, were seen far above the highest points reached. Half of the whole atmosphere is passed through when the altitude of 18,500 feet is reached; and air collected Vou. 1V.—No. 1. Z 170 Mr. J. Bryce on the Recent Progress of the at the greatest heights in no way varied in its proportion of oxygen and nitrogen from its state at the surface; it did not vary in com- position in the four ascents more than if collected at various points on the surface. The lowest observed temperature was about 11° F. below zero. Reasoning from these observations it may be concluded, according to Sir John Herschel, that at the top of the atmosphere over the equator, the temperature may be taken at —773°, and over-the pole at —1194°, supposing the surface temperatures to be respectively 82° F., and 0° F. (11.) With regard to the temperature of the celestial spaces, I am not able to find that anything has been recently added to what has been left us by Fourier, except some late speculations of Mr. Hopkins of Cambridge. Fourier placed the temperature of space somewhere about —60° F., but has, I believe, left no memorandum of the reasoning by which he was led to this conclusion. We know that the earth has either a fluid nucleus, or concentric fluid layers at an inconsiderable depth; that of about 10,000 feet, or two miles, would give us the temperature of boiling water ; the increase downward would soon become so great, that at a depth of twenty-four miles, we should meet with a temperature equal that at which iron melts, or 2,786° F.—a heat suf- ficient to fuse all known substances. Below this there may be a solid nucleus; the melted matter being arranged in concentric spheroidal layers.* Upon any hypothesis we may adopt, conduction and dissipation must be going on; but the passage of heat is so slow through stoney substances that the internal heat now annually dissipated is thought not greater than 77th of 1° F., or such as would in one year melt 2th of an inch of ice. The earth has arrived at this stationary condition. This heat is dissipated in space, and the radiation of the solar heat received is also constantly going on, but at what rate we are without exact data to fix. The stars and planets may also radiate heat into the planetary spaces, which may, by the combined causes, have some proper temperature of their own. In a late paper read to the Cambridge Philosophical Society, of which I have seen an abstract only, Mr. Hopkins, by a process of reasoning into which I cannot now enter, attempts to show that a minimum temperature exists within the earth’s * Such is the estimate hitherto formed. A different one, however, has been very recently made by Mr. Hopkins. From reasonings founded upon the results of the ‘‘ Experi- mental Researches on the Conductive Powers of Various Substances,” undertaken by re- quest, and at the expense of, the British Association, he draws the conclusion that the rate of increase of temperature downwards has been taken too great, and that the solid crust is not so thin as geologists have hitherto supposed.—(Abstract of Paper read to Royal Society, in Philosophical Magazine, April, 1858). Sciences of Meteorology and Terrestrial Magnetism. 171 atmosphere, but at a great altitude; and that just on the limit of the atmosphere the temperature will be intermediate between this minimum and that of planetary space, which he would make higher than either, the thermometer being of course supposed to be placed in shelter of all solar radiation, but open to every other influence. The paper is a specu- lation upon the degrees of heat which may exist on the surfaces of the planets; and the matter now referred to is introduced somewhat inci- dentally. He does not attempt to fix any temperature for the celestial spaces. (12.) The sun, it is now considered highly probable, may act as an agent in meteorological phenomena in another way than by the direct radiation before described. There seems to be a periodicity in its emission of heat, in connection with the number of spots at any time visible on the disc. The year 1856 has been remarkable for an almost total absence of spots; a like phenomenon was noticed about eleven years ago; and, in fact, from continued observations, it would seem that the spots recur in the same order and magnitude in ten or eleven years, giving about nine periods to a century—that is, from the minimum display to the munimum again is ten or eleven years. The spots are now universally agreed to be owing to vast openings in the luminous envelope, which display dark clouds within, or the opaque substance of a solid globe. This theory was first proposed by Dr. Alexander Wilson of the Glasgow Observatory and College in 1774, and adopted by Sir W. Herschel, without, however, any refer- ence to the source whence it was derived. The paper appeared in the Philosophical Transactions, and must have been known to Sir William. We do not know that his son has anywhere acknowledged Dr. Wilson, or explained the omission of his father in adopting the hypothesis without mentioning Dr. Wilson’s name. Most probably he took it for granted that all interested in the subject would know the source ; and it seems to have been his constant practice in all his papers to refrain from allusions to the past history of the inquiries, and to record merely his own observations, leaving it to others afterwards to weave the whole into a connected history. Arago, in his late work, has done ample justice to Dr. Wilson, and imputes no blame to either Herschel. Solar spots have been observed many times larger than the whole surface of the earth, some even as great as one-tenth the sun’s diameter. The least that could be seen by our existing instru- ments, must have a diameter of 461 miles, and an area of 167,000 square miles. It is obvious, therefore, that a great development of spots may considerably diminish the amount of heat emitted by the photosphere of the sun. Respecting the mechanical value of sunlight, 172 Mr. J. Bryce on the Recent Progress of the according to the principles of the dynamical theory of heat lately developed by Joule, Professor W. Thomson remarks,— Some idea of the actual amount of mechanical energy of the luminiferous motions and forces within our own atmosphere may be given by stating that the mechanical value of a cubic mile of sunlight is 12,050 foot pounds, equivalent to the work of one horse power for the third of a minute.”— (On the Density of the Luminiferous Medium, Zransactions of the Royal Society of Edinburgh, vol. xxi., Part I). We shall again recur to the solar influence when speaking of terrestrial magnetism. (13.) Some very curious facts regarding atmospheric temperature have been made known to us within a few years by scientific travellers, among whom two townsmen of our own are distinguished—Dr. Joseph D. Hooker, and Dr. Thomas Thomson. These relate chiefly to the situation of the snow line in Central Asia, and show us how dependent the elevation of this line is upon other causes than latitude merely. While the mean level of the snow line on the equator in S. America is from 15,200 to 15,800 feet, it rises on the inner ranges of the Tibetan mountains, about lat. 28° to 30°, and on the Karakorum mountains, lat. 33° to 35°, to about 20,000 feet! In the outer ranges of the Himalaya about Sikim, the level ranges from 13,000 to 18,000 feet, the mean being about 16,000 feet. In the same latitude in Spain, the snow line is 9,500 feet. The mean at lat. 0° being thus 15,500 feet, and at lat. 28° 16,000 feet, or 500 feet higher, the remarkable difference has no relation to latitude. The cause no doubt is the greater heating of the atmosphere from the larger extent of land in the latitude of Sikim, while in South America the land is narrower, covered with moist forests, and the Andes press close on the vast body of waters in the Pacific Ocean. In Bhotan, on the southern Himalaya, towards the head of the Bay of Bengal, where the mountains are open to the influence of the moist currents of the monsoon, and are protected from direct solar radiation by the fogs and mists thus generated, the snow line sinks to 13,000 feet. As we advance northwards, the line rises uniformly, reaching, as already stated, 20,000 feet. ‘This remarkable anomaly arises from the small supply of mois- ture, the lofty spurs of the chain towards the Indian plains intercepting the greater part of it, by the clearer sky permitting a more fervid radia- tion, by the great amount of heat reflected from the bare arid plains, and by the dry winds sweeping over these elevated tracts, under whose influence snow and ice evaporate without melting. Facts of exactly the same significancy have been made known to us regarding Norway by Professor James D. Forbes. Here, in lat. 60°, the snow line is at 4,450 feet near the coast; inland it rises 1,000 feet, or to 5,500; Sciences of Meteorology and Terrestrial Magnetism. 173 at lat. 66°, the respective elevations are 3,250 and 3,700 feet; and at lat. 70°, 2,900 and 3,350 feet. Here, as in the Himalaya, the rainfall decreases rapidly inland, the quantity deposited and the consequent prevalence of a cloudy state of the atmosphere having, in both cases, a manifest relation to the depression of the line of perpetual congela- tion. In Scandinavia the climate towards the coast has the insular type; that of Bergen is equable and damp: the heads of the larger fiords have less rain and a higher mean temperature; while the climate of the interior from Christiania northwards tends to approach the excessive or continental character. How influential are other causes besides distance from the equator, is strikingly shown by the circum- stances of South Georgia, South Shetland, and Cockburn island in the southern hemisphere. ‘These, though in a latitude varying from that of the mouth of the Tees to that of the Orkneys, are clad in snow to the sea level during most of the year; and produce among them but two herbaceous plants and one grass ; the rest of the vegetation being of mosses and lichens. (14.) The only observations that we know of as yet recorded regard- ing the temperatures on high mountains in these kingdoms, are those made within the last few years, by the late lamented Mr. Miller of Whitehaven. The minima given in a former memoir by this author (Philosophical Transactions, 1852), are stated in a paper in the Edin- burgh Z’ransactions for 1853-54, to have been found quite erroneous, owing to a change in the instruments, not discovered at the time. The mean difference between the absolute minima at Seathwaite, and the top of Seafell Pike, varies from 12°°7 to 18°8 in a difference of altitude of 2,798 feet. The average fall of temperature, as we ascend on the surface, may be taken here at about 1° in 215 feet. The details will be found in the latter paper. The instruments were placed upon Scafell Pike, the highest mountain in England, elevation 3,166 feet; and the monthly minima are as follows :—For the year 1853 in order, 10°, 8°, 11°, 11°, 20°, 35°, 87°, 35°, 29°, 27°, 23°, 12°. In the Seathwaite valley, adjoining on the N.E., at a station 368 feet above the sea level, the minima of the several months, in order, were as follows :—27°, 20°, 22°, 33°, 36°, 47°, 50°, 45°, 42°-5, 85°, 31°, 19°. The winter mean at White- haven, deduced from a long series of observations, by Mr. Miller, is 44°*7 F. These temperatures are in no way remarkable ; much greater degrees of cold having been experienced in Lancashire, Yorkshire, the Midland Counties, and at London, during the months of December and January, than on these mountains. While Seathwaite shows but 19° and 18° ’., the minima in the other places just named, ranged from 10° to —4° F In fact these mountain valleys, and even mountain tops have a com- 174 Mr. J. Bryce on the Recent Progress of the paratively mild and equable climate. The high minima on Scafell and the other mountains is, however, in great part due to the thermometers being covered with snow in the coldest months. They show a mini- mum of only 8° to 10° F.; while, there can be no doubt, that in the air, a temperature considerably below zero would have been indicated. (15.) The temperatures of a great many stations in India, are given in a long and elaborate paper by Col. Sykes, in the Philosophical Transactions for 1850, to which we can only now allude. Reference will again be made to it under the head of “ Atmospherie Pressure.” (16.) From a comparison of registers, kept for more than thirty years at Berlin, with others in various places, Miedler concluded that a general depression of temperature took place over the whole globe, on the 11th, 12th, and 13th of May. To this view a discussion of the Toronto observations lends no countenance; and Major-General Sabine considers that, as a general law, the theory is by no means established, though true as regards Berlin. From the same discussion, it appears that the summers in N. America have not a greater degree of warmth than is due to the latitude; but that the winters are much below the mean temperature due to it. The mean is, in fact, for this season, about 7° F. below the normal temperature of the latitude. At Toronto, it is even more than this; the thermic anomaly,—that is, the difference between the temperature actually experienced and that due to the lati- tude being there 11° F. The mean annual range, or the difference between the hottest and the coldest months (July and February), is 42°°7. The hottest day is the 28th July; the coldest the 14th of February; and the mean temperature, 44.°°23, is passed through on the 19th of April and 15th of October. A paper on the climate of North America, containing some new and very remarkable views, will be found in the Report of the Glasgow meeting of the British Association. The discussion of the Toronto temperature observations is given at length in the Philosophical Transactions for 1853, Part I. (17.) Much attention has been given of late to the important subject of a change in the zero point of thermometers. Such a change has an obvious connection with the trustworthy character of instruments long in use, or exposed to new conditions, and is thus worthy of the closest attention. It is suspected that such a change may have taken place in the earth thermometers at the Edinburgh Observatory ; and the sub- ject is now engaging the earnest attention of Prof. C. Piazzi Smyth. Mr. Welsh of the Kew Observatory has also investigated the subject, and has recently put forth some important views in a paper, of which an abstract is contained in the Report of the Hull meeting of the British Association, 1853. An important mathematical paper, by Mr. Sciences of Meteorology and Terrestrial Magnetism. 175 J. J. Waterston, bearing on the same subject, will be found in the Philosophical Magazine for March, 1858. ‘CLoups anp Ratn. (18.) To this department of our subject some important additions have been made of late years. Meteorologists have long been divided in their views regarding the internal constitution of clouds, and the nature of fogs and vapour. These are all of the same integrant struc- ture—that is, they consist of minute spherules, suspended at greater or less heights in the air. We call them fogs or mist, when resting on the surface of the earth; when raised aloft, and viewed en masse, we name them clouds. It is obvious, however, that there are differences in the state of aggregation, or the degree of closeness among the particles ; and these different states of density may develop peculiar forces among the component molecules. Now, some hold that the spherules are hollow, and that the water serves only as an envelope, as in the case of a soap- bubble; others maintain that they are without internal cavity, and resemble globules of quicksilver. Kaémtz inclines to the former view (Meteorology Translated, by Walker, p. 109, 1845). In his first report to the British Association (Vol. I. of Reports, 1833), Prof. J. D. Forbes does not directly consider this branch of the subject. In his second report (Report of Tenth Meeting, 1840), he merely alludes to it in a short paragraph, and seems to incline to the view that the component particles are vesicular (Note, p. 111). Professor Stevelly, of Belfast, who has long given special attention to this part of the subject, adopts the view that “the constituent particles are minute spherules, but not vesicles.’ He refers their suspension to two causes—“ the extreme slowness of descent through the air of such exceedingly minute particles, and the repulsive action of the electrical atmospheres of these particles upon the ambient air (Fourth Report British Association, 1834). The idea of electrical atmospheres originated, we believe, with Mr. Henry Eeles, of Lismore, in Ireland, about the year 1750. His views on this and other collateral subjects were communicated to the Royal Society (Philo- sophical Transactions, 1752), and afterwards published in a small octavo volume, under the title of Philosophical Essays, Dublin, 1771. He supposed that the vapour ascended in vesicles, enveloped by such an atmosphere, but descended in drops, receiving accretions as they fell. This branch of meteorology is still involved in great obscurity—as well . the internal structure, mutual dependence of the parts, and mode of suspension of clouds, as the entire subject of atmospheric electricity. There can hardly be a doubt that some such agency as Mr. Eeles sug- gested is actively at work in the production of rain and hail, especially 176 Mr. J. Bryce on the Recent Progress of the the latter. It has been lately detected in many cases by Mr. Manuel J. Johnson, at the Oxford Observatory, by means of the admirable contrivances there adopted for automatic registration by photography. But these have been so recently established that we must await the result of more extended observations before attempting to generalize. Sir John Herschel has expressed his decided opinion (Hncyclopedia Britannica, new edition, vol. xiv.), in opposition to most meteoro- logists, that lightning is a consequence and not a cause of sudden precipitation of large quantities of rain and hail. “The utmost amount of electrical agency which we can conceive influential in deter- mining precipitation is the sudden relief of tension, that is density, on the discharge of a flash, which, aided by the vibration of the thunder- clap, may favour the coalescence of globules into drops, which otherwise would have been kept asunder by their mutual repulsion. As a chemical and magnetic agent, electricity is important; but it can only produce such atmospheric movements as are merely molecular.” The negative electricity produced during rainfalls, Faraday has shown to be caused by the friction of water-drops against the substance rubbed. The same is found in the spray of waterfalls, even at several hundred feet dis- tance. Respecting clouds, Mr. Drew, in his late excellent little work on Practical Meteorology (Van Voorst, 1855), thus writes—“ We are told by some that they are vesicular vapour; this is simply a hypothesis ; we can only affirm with certainty that they consist of particles of aqueous vapour in a peculiar state of aggregation, and that they float in the lower regions of the atmosphere. That electricity affects their state is pretty certain ; but facts are wanting on which to found a theory as to its mode of operation.” (19.) In this state of uncertainty, the observations and experiments of Dr. A. Waller, of Kensington (Philosophical Transactions, 1847. Part L.), are a welcome gift to meteorologists. He appears to have succeeded in showing that vapour consists of globules or spherules, without any inter- nal cavity; that the minutest component molecules are not vesicular, but water to the centre. He examined the globules by the microscope in various ways. The ova-bearing filaments of the spider’s web, and the cocoon of the silkworm, were exposed to the steam of boiling water, which was condensed upon them. In fogs also the web, covered with globules, was removed, and fixed between small glass plates. Another method employed was to cover a slip of glass with a thin coating of Canada balsam, and to breathe on it. The moisture was found to remain for many hours in minute globules on the balsam, and also to sink into it below the surface. The forms were irregular—not perfect spheres. In both cases the globules coalesced, and formed larger ones, Sciences of Meteorology and Terrestrial Magnetism. 177 in exact proportion to the solid globules united. The diameters of the original globules were estimated at ‘001 to ‘003 of a millemétre, or 000039 to -000118 of an inch! Those condensed from boiling water were also irregular in form, and from ‘02 to *03 of a millemétre, or from ‘000787 to ‘001181 of an inch in diameter. When the glass slip, with its balsam coating, was laid upon grass covered with hoar frost, globules gradually formed on the surface. These were estimated at less than 0001 of a millemétre, or 000003937 or 4-millionths of an inch in diameter!! Water at 167° F. gave globules of the same size as those from the breath. A further proof of the non-vesicular character of the globules was their permanency when enclosed between the glass plates. Besides, globules of air or other gases were found to be very different from these ; they were larger and darker. On one of them, from ‘01 to ‘02™™: in diameter, an extensive landscape of trees, houses, &c., was pro- jected. Bright objects, viewed through the water globules of ‘001 to °003™" in diameter, were surrounded by a halo, like those seen around the sun and moon.—But it is unnecessary to abstract this paper in greater detail. It is well worthy of a careful perusal by those who are interested in the subject, and will be found very curious and instructive. The views put forward do not lessen the difficulties attendant on an explanation of the cause of the suspension of clouds. But so little defi- nite knowledge is possessed by us as yet on this subject, so far as I am aware, that I must content myself by a reference to the works already quoted for the prevalent notions. No change has been introduced into the nomenclature of clouds; that of Mr. Luke Howard, proposed in 1802, is still used by meteorologists. Many new and curious observa- tions on the subject of clouds and erial currents will be found scattered through the instructive and fascinating work already referred to, Prof. C. P. Smyth’s Residence Above the Clouds. A series of very ingenious experiments has recently been contrived by Mr. Jevons, of the Royal Mint at Sydney, N.S.W., to illustrate the mode of formation of the different varieties of cloud. By peculiar appa- ratus of his own devising, liquids of different specific gravities, specially adjusted, are mixed, one liquid being injected into the other. The effects produced exhibit to the eye a close resemblance to those observed in the atmosphere ; and he uses these as proofs of a theory of the origin of clouds, differing in some respects from that generally received, and described in works on meteorology. The papers will be found in the Philosophical Magazine for July, 1857, and April, 1858. (20.) Very little progress has been made of late years towards the construction of a theory of rain, founded on the true basis of a careful induction of facts. The observations of Professor Phillips, so admirably Vor. 1V.—No. 1. 2A 178 Mr. J. Bryce on the Recent Progress of the worked out theoretically, were a great step in this direction; but many more will be required, at various altitudes, and under different climates, before a general law can be deduced, expressing the decrease of the quantity of rain from the surface of the soil perpendicularly upwards. The views which he has developed are well known to meteorologists, and have met with general acceptance. An account of them will be found in the third, fourth, and fifth Reports of the British Association, also in Professor Forbes’s second Report to the British Association, 1840, where they are spoken of with high approval. They were not put forward as com- plete, but merely as a partial solution of a most difficult problem, await- ing further and extended observations for its complete solution. In this state it still remains, receiving, however, occasional illustration from registers kept in various places. (21.) While the quantity of rain is thus known to increase from _ moderate altitudes -downwards—most probably from the drop gather- ing fresh vapour upon its surface, in consequence of its having a lower temperature than the vapour through which it successively passes in its descent, just as a decanter of cold water, brought into a warm room, becomes covered with dew—it must be borne in mind that the absolute quantity of rain which falls on high grounds is greater than that received on low surfaces towards the sea level. Hills attract and cool vapour, and cause a deposition of moisture, which might otherwise be borne away, or re-dissolved into steam on meeting with warmer currents. Hills near the sea have a much greater quantity on their south-west than on their north-east sides, and that in Asia as well as in Europe. The case of Norway and Sweden has been mentioned already. Towards the mouth of the Frith of Clyde, as at Greenock and Dunoon, and among the hills northward, as at Lochgoilhead and Arrochar, the rainfall is from fifty to sixty inches ; at Glasgow and Paisley, no more than 35°27 inches. The lake mountains of Cumberland and Westmoreland, rising abruptly from the Irish Sea, towards which three principal valleys open out, have the greatest rainfall yet known in Great Britain, or perhaps in Europe. The latest results of Mr. Miller’s long continued inquiries on this subject are given in the Philosophical Transactions for 1852, Part I. The wettest spot in the district is 100 yards south of the top of Styehead Pass, elevated 948 feet above the sea, and 580 feet above Seathwaite. In 1850 the rainfall at this spot was 189°5 inches. But 1848 was a wetter year; and if the ratio of increase in that year was the same at this spot where a gauge had not then been established as at the other stations, he reckons that the amount would have been 211°62 inches. At Seathwaite the amount varies from 144 to 161 inches in the different years, or 50°62. inches less Sciences of Meteorology and Terrestrial Magnetism. 179 than on the Styehead Pass, distant a mile and a-half. Passing from the sea level up the valleys above mentioned, the quantity of rain increases rapidly, and at the heads of the valleys augments im- mensely (Philosophical Transactions, 1849, Part II). Thus the quantity is one-fourth greater at the head of Eskdale than in the middle of the valley; at Ennerdale it is nearly double the amount at a farm house three miles west. As the heads of the valleys are reached, a few hundred yards make a remarkable difference. The amount goes on increasing up to 2,000 feet, and then begins to diminish, the air at this altitude being about saturation ; getting colder upwards, it holds a less quantity of vapour in solution. (22.) Not less remarkable are the prodigious quantities of rain which have been recently ascertained to fall in some parts of India, exposed to the full influence of the south-west Monsoon. The meteorology of India is fully considered by Colonel Sykes, in a long paper in the Philosophi- cal Transactions for 1850, Part II, We have here only to consider the rainfall. The amount annually deposited on the West Ghauts, against which the warm winds, loaded with moisture, first impinge, is very great. The quantity which falls at Cape Comorin—a low point—is very slight ; but a few miles north, where hills rise to 2,000 feet, it is 112 inches annually. Colonel Sykes considers that the chief rain-bearing current is seldom much higher than 2,000 feet ; for, standing on heights greater than this, he has often seen the rain-clouds below; but, when driven by the west winds they strike against the steep wall-like barrier fronting in that direction, they rise to heights very much greater, and suddenly cooled by the lofty summits rising above the general level of the Range, deposit a prodigious quantity. The maximum fall yet recorded on the West Ghauts takes place at Uttray Mullay in Travan- core, latitude 9°, where the amount was 263:21 inches, the mean of two years. At Mahabuleshwar, latitude 18°, the rainfall was 254-84 inches, the mean of fifteen years; and of this quantity 1342 inches fell in the month of July alone. The mountains here attain an elevation of 4,500 to 4,700 feet, 2,300 higher than the Deccan plateau inside the Range. At places where valleys, or rather gullies, opening from the low tract seaward, cut the Range deeply, the quantity is much less, because the rain-clouds escape eastward across the Deccan, and deposit their load of moisture gradually. The maximum fall he places at about 4,500 feet; the quantity above and below this plane being less. Thus at different elevations on the Travancore Range, the quantities are as follows :—At 500 feet, base of Range, 99 inches; at 2,200 feet, 170 inches; at 4,500 feet, 250 inches; at 6,200 feet, 194 inches. The fall at Bombay is 76:08 inches, the mean of thirty years; and at other 180 Mr. J. Bryon on the Recent Progress of the stations on the coast near the sea level, ranges from this amount to 82 inches; at heights varying from 150 to 900 feet, the fall varies from 115 to 135 inches; at 1,740 feet on the Kundalla Pass, leading from Bombay to Poonah, 142 inches; and on the highest points, ranging from 6,000 to 8,640 feet, the highest of the West Ghauts, the quantity deposited varies from 82 to 101 inches; the maximum being always about 4,500 feet. We have already alluded (Art. 10, 14) to the differ- ent conditions under which the air is placed as regards temperature and humidity, when in contact with a mountain slope, from those which prevail within its mass, when we ascend vertically over any space removed from such disturbing influences. The balloon ascents also illustrate this difference. In open situations above the level sur- face of the ground, the law of Professor Phillips, stated in Article 20, is said to hold good for altitudes in India not passing a few hundred feet. Great as is the rainfall here recorded, a still more remarkable case remains,—that, namely, of the Khasia Mountains at the head of the Bay of Bengal, between Assam and Burmah. We learn from Dr. J. D. Hooker that the south fronts of these hills, which attain a maxi- mum elevation of 6,662 feet, with a general level of 4,000 to 5,000, arrest the cloud-bearing current brought up by the Monsoon from the Bay of Bengal, and cause a deposition of the moisture along their cool fronts to the enormous amount of 540 inches, and sometimes 610 inches in the year,—a quantity which, if not evaporated from day to day, absorbed, or run off, would cover the surface to the depth of fifty feet. A portion of the cloud-bearing current, however, passes over these hills, and is caught by the higher ranges of the Bhotan Himalaya, which, while arid and treeless below 6,000 feet, above that level are well watered, and nourish a luxuriant vegetation (see Art. 13.) Reserving the remaining portions of Meteorology proper, as Pressure of the Air, Radiation, Meteors, &c., for a second Report, we shall pass on now to the collateral subject of Terrestrial Magnetism. TERRESTRIAL MAGNETISM. (23.) The various branches of physical science have so close a connec- tion with one another, that it is difficult to adopt a classification of them which-shall be quite satisfactory. To explain the phenomena of one branch, the laws of another must constantly be referred to. This is especially true of Meteorology, whose multiplied objects and many complex problema ally it to geography, astronomy, chemistry, optics, and pure physics, and require the aid of the higher mathematical ana- lysis. As referring to the great physical agencies at work in the earth’s Sciences of Meteorology and Terrestrial Magnetism. 181 atmosphere, or operating through this medium, Terrestrial Magnetism may in this view be regarded as a branch of Meteorology. It is cer- tainly not an inapt classification to regard it as such, in the state to which the science has now arrived. Without entering fully into the subject here, we shall merely set forth a few of the more striking results lately established ; a full detail is impossible, as perhaps no other branch of this great subject has made so much progress, been so systematically and ably pursued, or called forth an equal refinement and skill in the construction of instruments and methods of observing. The credit is mainly due to the Norwegian Parliament and the British Association— the latter at length liberally aided by her Majesty’s Government. The chief actors in this great undertaking were Hansteen of Christiania and Major-General Sabine of the Royal Artillery. The mathematical theory has been most ably developed by M. Gauss of Gottingen and our distinguished president, Professor W. Thomson—the latter, in a series of papers read before the Royal Society, beginning in 1851. We be- lieve that the first suggestion of combined and continuous observations on certain days, previously fixed, is due to Baron Humboldt, whose appeal to the Royal Society on the subject led to the adoption, on the part of our Government, of those extensive inquiries which Major-Gene- ral Sabine has conducted to so successful an issue. For the investiga- tion of certain formule, necessary to the right conduct of the inquiries, he acknowledges his obligations to Mr. Archibald Smith of Jordanhill. The most important instruments by which the inquiries have been conducted are due to the ingenuity of M. Gauss, and Professor H. Lloyd, of Trinity College, Dublin—Other Governments lent a willing assistance, especially that of Russia, whose vast territories are celebrated for the most striking displays of magnetic phenomena. (24.) The King of Sweden, in 1829, requested a grant of money from the Norwegian Storthing to build a new palace at Christiania ; the parliament resolved that the king could wait, and granted a sum of the same amount to send Hansteen to Siberia, to determine the position of the eastern magnetic pole, and for collateral magnetical objects. The western magnetic pole had been already fixed by Commander Ross, now Sir James Clark Ross, off the north-west of America. The celebrated voyage which Ross made to the antarctic regions, in 1840-2, already referred to, was undertaken at the public expense, on the representation of the British Association. Observatories were also established at Hobart town, the Cape, St. Helena, and Toronto—critical stations pointed out by our men of science. Officers on foreign stations or on voyages in various seas, were instructed how and what to observe. The magnetic elements and their changes were the chief subjects of research, 182 Mr. J. Bryce on the Recent Progress of the coupled, of course, with those of temperature and pressure. General Sabine discussed, arranged, and published the results. It is now pretty clearly ascertained that there are four magnetic poles, that is, four points on the earth’s surface, where the dipping needle stands in a vertical position, and which (for distinction’s sake), we may call poles of verticity. The west pole was fixed in Boothia Felix, in lat. 70° 5°17" N., long. 96° 45’ 48" W. Another pole lies in the north of Siberia, in lat. 82° 3’, long. 114° 83’ E, In the southern hemisphere the poles of verticity have been placed, by the researches of Ross, in lat. 68° 51’, long. 131° 38’ E.; and south of the American continent nearer the pole of the earth, namely, in lat. 76° 7’, long. 143° 34 W. The latter he was unable exactly to reach, on account of the magnificent barrier of ice, which presented lofty cliffs seaward, in front of Victoria Land, through a distance, nearly east and west, of 1,000 miles. Most persons will remember the striking descriptions which Ross gives of this wondrous region—the ice covered land with its lofty voleanoes rivalling Mont Blanc in altitude, and its high icy cliffs presenting a crystal barrier to the roll of the antarctic waves. Here, amid volcanoes and glaciers, lies unapproachable the western magnetic pole of the southern hemisphere. (25.) Besides these poles of verticity in both hemispheres, there are also poles of maximum intensity, distinct, and considerably removed from the poles of verticity. The intensity of the force is estimated in the same way as that of the force of gravity in different latitudes, by means of the oscillations of a pendulum—a freely suspended needle is with- drawn from the meridian, and oscillates a certain number of times in resuming its original position. This being done at different points, the intensities at those points are in the ratio of the squares of the numbers of oscillations. Thus, if at two points the number of oscilla- tions are 24 and 25, the intensities at those points are as 576 : 625, or 1:000:1:085. These intensities have been estimated with great care in so many parts of the globe, that lines can be laid down upon a map connecting them. These are the isodynamic lines, or lines of equal intensity. They form at first regular ellipses around the poles of inten- sity, and change into various forms, chiefly looped curves, like the figure eight. The position of these “ intensity poles’? has been accurately determined within the last four years for the northern hemisphere; the western most recently. It is situated near the south-west corner of Hudson’s Bay, in lat. 52° 19’, long. 92° W. Here, and at Toronto, the inclination is about 753°. Another pole of less intensity is in Siberia, about long. 120° E. The total force has clearly two compo- nents—that which produces declination, or variation east and west, and Sciences of Meteorology and Terrestrial Magnetism. 183 that producing dip, or inclination. The inclination is properly the angular amount of dip. Now these have been separated, and estimated as the horizontal and vertical components of the force. An admirable contrivance for the purpose is due to the ingenuity of Dr. H. Lloyd of Dublin. The total force is estimated in numbers, the unit being 1 grain in weight, 1" in time, and 1 foot in space; or the force is such as in |" would generate in 1 grain a velocity of 1 foot—just as the force of gravity is 32%, though in the first second 16, feet is the space passed over. Estimated thus, the force at the point of maximum intensity in Canada is 14°21; at Toronto, 13°896; at Greenwich, 10°388. In the southern hemisphere, it is 15°600—the point of maximum intensity there best ascertained being about lat. 60° S., long. 185° E. Another intensity pole is in lat. 20°S., lon. 36° W. These four foci or intensity points are constantly changing their positions—the two northern shifting eastwards, and the two southern westwards; the weaker, or eastern pole, in Eastern Siberia, moving much faster than the stronger or western, in Canada; so that they are approaching one another in a line, crossing from Siberia, through Russian America, towards the south of Hudson’s Bay. In this intermediate space the total force is increas- ing.—To other determinations and results I cannot now allude, and shall further only state a few facts, very recently ascertained, bearing closely on the theory of terrestrial magnetism, and tending to with- draw the science from the category of terrestrial agencies, and to place it in the class of the “ great cosmical phenomena.” (26.) A horizontal magnet has variation with the hours of the day, so that, running through several changes in the advance of the hours, from sunrise to sunrise, it returns to its former position at the expiry of the time, to begin a new set of variations. It attains its maximum when the sun is 2" past the meridian of the place of observation,—say any- where in Europe.—With us this would be 2” p.m.; but at Constanti- nople it would be 4 p.m. of our time; and at the Azores 10" a.m. of our time. This change, then, is clearly dependent on the sun’s passage of the meridian of the observer. Now, this diurnal variation is not the same at all times of the year,—it runs through a series of changes, the period of which is one year; so that the diwrnal variation has an annual period; the same condition of things being again established on the expiry of the year, and coming round again the next year in like order. But the variations are not the same in each of the hal@years forming the annual period. They differ with the lapse of the two semi-annual periods from April to September, and from October to March. These changes, however, have no relation to summer and winter, or to the seasons of the year; for they correspond most remarkably at the three 184 Mr. J. Bryce on the Recent Progress of the stations of Toronto, St. Helena, and Hobart town, the former having summer while the latter has winter; and St. Helena scarcely any dis- tinction at all. The epoch of change at all the stations, from one class of phenomena to the other, is the sun’s passage across the equinoctial. This clearly points to an effect of the sun upon the magnetism of the earth as AMASS. It has been found, too, that the changes of variation in the two half-yearly periods almost coincide with the day of the equinox ; but it requires some time to complete the change, and bring round a marked difference in the variations. Gen. Sabine states that this may be compared to the change in the induced magnetism of a ship, by a change in geographical position; it is not accomplished at once. The greater proximity of the sun in December than in June, has also been shown to produce an effect on the intensity of the force; but by no more than ‘002 of the whole. This also is the same .at all the stations—clearly pointing to solar influence on the whole earth. Now, it is remarkable, as showing how erroneous were our former ideas, in regarding these variations as due to terrestrial temperature, that M. Dové has proved that, at this very period, namely, in the months between October and February, when the inclination and total force are greatest, and the sun xearest us, the aggregate temperature of the whole earth is Jess than at the opposite season—a diminished temperature clearly due to the smaller quantity of land in the southern hemisphere. This most emphatically points to great cosmcal influences, quite beyond the earth and its atmosphere, and indicates the sun as a vast magnet. But conclusions still more interesting and remarkable, regarding a con- nection with, and dependence upon the sun have been established. I have already referred to the solar spots, and their periods of abundance and paucity—in these, also, we now detect a relation to magnetic dis- turbance. When the spots are at a minimum state of exhibition, only 30 or 40 appear in a year; but when at a maximum state, 300 or 400. The period from minimum to minimum is ten or eleven years. Now, it has been found that unusual magnetic disturbances or storms, as they are called, coincide with the period of abundant spots, and that these storms run through a decennial period, or recur, after ten years, of similar character and intensity. The year 1843 was a year of mini- mum in the spots; 1848, a year of maximum. From the former to the latter, the magnetic disturbances increased in frequency and aggregate values; the aggregate in 1848 being three times greater than in 1843. The relation being thus suspected, calculations for previous dates of maximum and minimum among the spots, and of magnetic disturbances, were entered into, and the results have shown that, so far back as the accurate system of observations has-gone (about twenty-six years), Sciences of Meteorology and Terrestrial Magnetis.n. 185 the correspondence is truly remarkable. To put this striking con- nection almost beyond a doubt, Gen. Sabine found that the mean diurnal variation exhibited a change in different years, and had a maxi- mum and minimum correspondence with the solar spots; and that 1843 and 1848 were two such periods. On calculating backwards for previous epochs of the spots, there was found an exact cor- respondence. The moon, also, has been recognized, first by M. Kreil, director of the Austrian observatories, and since by Gen. Sabine, as slightly influ- encing the variations of the magnetic elements; but here there is no trace whatever of a decennial period. These late results are extremely striking, and open up to us new views regarding the great cosmical phenomena, as well those relating to the earth and its magnetism, as to the constitution and action of the great photosphere of the sun himself. —They seem to point to vast secular changes in the magnetism of the sun ; and, in connection with the highly probable existence of a magnetic medium, pervading all space, suggest new relations among the imponderable agents,—heat, light, electricity, and magnetism, which play so important a part in the economy of the universe. January 13, 1858.—The Prestpent in the Chair. Mr. William Gilmour was elected a member. Mr. Thomas Nicolson, Writer, 20 Buchanan Street, was proposed as a member by Mr. James Young, Mr. John Ure, and Mr. Keddie. Mr. Edmund Hunt gave further illustrations of his paper “ On certain Phenomena connected with Rotatory Motion.” Professor William Thomson showed, by a series of experiments, the different conductivity of various samples of Copper Wire. . The inquiry was suggested by circumstances which arose in connection with the con- struction of the Atlantic Telegraph Cable; and the results which have come out are very surprising, and such as no one had anticipated. The power of transmitting an electric current differed extremely in different specimens of wire, though these were manufactured in the same way and at the same establishment. Chemical analysis showed no difference in composition ; and that the state of crystalline aggregation had no effect, was proved by the circumstance that stretching, twisting, or compression in no way affected the conductivity. The cause of the difference must be held as still entirely unexplained; yet so great is this diversity of conducting power, that the use of the best conducting wire Vor. IV.—No. 1. 2B 4 186 Minutes of Meetings. in place of the worst, would make a difference in the cost of the Atlantic Cable of £100,000 sterling. The result has been, that now, in the actual construction of the Cable, a testing apparatus has been put up, and all those specimens of wire are rejected which do not come up to the standard maximum of conductivity. The Professor exhibited a similar apparatus, and illustrated his views by experiments with differ- ent samples of wire. In the conversation which followed the reading of the paper, Dr. Francis Thomson and Mr. James Bryce suggested certain theoretical considerations towards an explanation of these singular phenomena; but the Professor seemed to have anticipated them, and did not appear to regard them as satisfactory. The cause, he held, was still involved in complete mystery, while the facts were undoubted, and of the utmost practical value. Mr. James Young described a new method of constructing Submarine Tunnels. January 27, 1858.—The Prestent in the Chair. Mr. Thomas Nicolson was elected a member. Mr. Bryce, in absence of Mr. Keddie, exhibited a fragment of one of the turrets of the tower of Glencairn Parish Church, which had been struck by lightning, and showed that the siliceous particles of the sandstone had been fused in the course of the electric current. Dr. Anderson, the Librarian, announced the presentation to the Library of the following Books, viz. :— Transactions of the Historic Society of Lancashire and Cheshire, vol. ix., Session 1856-57. Memoirs of the Literary and Philosophical Society of Manchester, vol. xiv. Proceedings of the Literary and Philosophical Society of Liverpool, Session 1856-57. Journal of the Royal Institution, Part VII., 1857. Transactions of the Philosophical Institute of Victoria, vol. i., 1857 ; and Part I., vol. ii., Laws of the Philosophical Institute of Victoria. Report of the Committee of Management of the Melbourne Mechanics’ Institution and School of Arts, for the year 1856. Proceedings of the Natural History Society of Dublin, Session 1856-57. Dr. Thomas Anderson read a “‘ Report on the recent Progress of our Knowledge of the Chemical Elements.”’ 187 Report onthe Recent Progress of our Knowledge of the Chemical Elements, By Dr. THomas ANDERSON. He commenced by observing that the progress of a science is rarely uniform in all its departments, but that now one portion and then an- other claims the special attention of its cultivators, and advances with more than ordinary rapidity. The truth of this statement is well illustrated by our knowledge of the chemical elements, a subject which within the last few years has been studied with remarkable activity, and has given a rich harvest of new and unexpected results. After the brilliant discoveries which marked the end of the last and beginning of the present century, among which it is scarcely necessary to refer to the isolation of the alkaline metals by Davy, and the discovery in France of iodine and bromine, a long period elapsed during which scarcely any- thing was added to our knowledge of the elements, and in fact the dearth of novelty was so great that the belief gained ground that this department of chemistry had been completely exhausted. The fallacy of this idea was demonstrated, and a new epoch of progress in this branch of science commenced by Mosandeyr’s discovery of Lantanium in the year 1839, a discovery of peculiar interest, because it indicated a method of inquiry by which great additions to the number of the elements have since been made. In the year 1803, Berzelius and Hisinger discovered a metal to which they gave the name of Cerium, and which had remained without further examination until it was again investigated by Mosander, who found it to be really a mixture, as he at first believed, of two, but as he subse- quently showed, in 1841, of three different metals. For one of these he retained the name of Cerium, and the other two he called Lantanium and Didymium. These substances had escaped the notice of Berzelius and Hisinger, because they operated on a very small scale, and as the metals, though unequivocally different, are very similar in many of their properties, it is easy to understand how they came to be over- looked. Of the metals themselves very little is yet known, but the oxides are readily distinguishable; thus, for instance, the oxide of cerium is yellow or buff, that of lantanium white, and that of didymiur dark brown. Their separation is very difficult and depends mainly on the difference of their affinity for acids. The result of his investiga- tion led Mosander in 1843 to examine the metal Yttrium, which was discovered by Gadolin in 1794, and it also proved to contain three dif- ferent substances, which are now known by the names of Yttrium, Erbium, and Terbium; all derived from Ytterby, the name of the place where the mineral containing them is chiefly found. The separation is 188 Dr. ANDERSON on the Recent Progress of our effected in a manner similar to that of the Cerium and Lantanium. Owing to the rarity of the minerals containing these substances, very little is yet known regarding their properties; indeed, the metals themselves have not yet been separated, and even their oxides have been most imperfectly examined. Shortly afterwards, Svanberg was induced to examine Zirconia, being led to anticipate the possibility of different substances being found in the zircon of different localities, from the conspicuous differences, and their specific gravity, which varies at between 4°0 and 4-7, and he believes that the Zirconia of Berzelius contains three different substances. To one of these, which gives a readily crystallizable sulphate, he has assigned the name of Noria, and to its metal Norium. It is found most abun- dantly in the Norwegian Zircon. Eudialyte, according to Svanberg, also contains two new earths, one resembling Yttria, the other yellow. It is right, however, to mention that considerable doubt still attaches to these substances, and Berlin has failed to confirm Svanberg’s results. In the year 1801, Hattchett discovered in an American mineral a metal which he called Columbium, and in 1802 Ekeberg found in a Swedish mineral another which he named Tantalum; and in1809, Wollas- ton declared these substances to be identical. Rose was led to re-examine this subject in 1846, by observing the great difference in specific gravity of the Tautalites of different kinds, the black variety from Bodenmais having a specific gravity of 6°39, while the reddish-brown from the same locality is 5°69, and the American 5-70, and he found them to contain a metal distinct from Skeberg’s Tantalum, to which he gave the name of Niobium. He also at the same time stated that they contained a third metal which he called Pelopium, but subsequent experiments satisfied him that it was not adistinct substance. The metals, Tanta- lum and Niobium, are scarcely known, but they both form acid compounds with oxygen, which are distinguished by very marked differences. One of the most curious is the effect of heat in modifying their specific gravity, Tantalic acid in its ordinary state having a specific gravity of 7-284, which is increased by a strong heat to 7°99, while Niobic acid is reduced by heat from 5:12 to 4°60. A mineral, very similar in properties to Yttrotantalite, has been found in the Ilmen mountains in Siberia, to which the name of Yttroilmenite has been given. Herman, who has examined this mineral, believes it to contain a metal which he calls Ilmenium, but Rose considers this to be merely niobium contaminated with a little tungstic acid. The residues obtained during the purification of platinum have also yielded a new metal, which its discoverer, Claus, calls Ruthenium. It is Knowledge of the Chemical Elements. 189 infusible in the highest heat of a furnace, and has a stronger affinity for oxygen than any of the platinum metals except osmium. It thus appears that the number of elements has, during the last twenty years, been increased by certainly seven or eight, and, if we include the doubtful substances, by not less than adozen. And these have been discovered by a revision of the earlier investigations of chemists of the highest eminence. They have all been detected in minerals of great rarity, and owing to the difficulty of obtaining the raw materials from which they are extracted, their properties are still very imperfectly known, and offer an extensive field for further inquiry. But if the additions to the number of the elements are remarkable, the increased information obtained regarding those of older discovery is even more striking. The atomic weights of the greater number have been determined with additional care, and all the refinements of the improved analytical chemistry have been brought to bear upon the experiments ; and while the result of these inquiries has been to confirm in most instances the numbers given by Berzelius, some not unimportant corrections have been introduced. The tendency has been to show that the atomic weights of most of the elements are multiples of that of hydrogen, although some remark- able exceptions to this rule have been observed. This is particularly the case with chlorine, whose atomic weight is now universally admitted to be 35:5, and not 35. The progress which has been made in the study of the properties of the known elements is equally great, and has led to most important discoveries. Perhaps the most interesting of these is the possibility of obtaining an element in two different forms, in which its properties are conspicuously distinct. Of these the most remarkable is that form of oxygen in which it acquires a pungent and irritating odour, and the property of decomposing many compounds which resist its action in its ordinary state. In this form oxygen is known by the name of Ozone, which was applied to it by Schénbein. He obtained it chiefly by the action of the electric spark and moist air, but a French chemist, M. Houzeau, has lately shown that it is obtained by the action of sulphuric acid on peroxide of barium ata sufficiently low temperature. By no process yet known is it possible to convert oxygen entirely into ozone, and hence considerable difficulty attends the determination of all the properties of the latter; but it would appear from the recent researches of Andrews, that its specific gravity is four times that of ordinary oxy- gen. It has been long known that sulphur varies greatly in its properties, and in addition to its two crystalline forms can be obtained also as a soft black substance, but it appears that it is capable of still further varia- 190 Dr. ANDERSON on our Knowledge of the Chemical Elements. tions, and can be obtained as a white or yellowish matter insoluble in bisulphuret of carbon. Deville, Schrétter, and Magnus have made a large number of curious observations on these points. Selenium, which in its usual condition is an amorphous and glassy substance, can also be converted by heat into a crystalline mass insoluble in bisulphuret of carbon, and into another kind of crystals soluble in that re-agent. But probably the most remarkable among these changes is that offered by Boron, which has been long known amorphous, but which Deville has recently obtained in a crystalline form, in which it can scarcely be distinguished from the diamond, and in another state in which it resembles graphite. The diamond boron 1s obtained by heating amorphous boron or boracic acid in contact with aluminium to a high temperature, and then dissolving the aluminium in potash, when the boron is left in colourless or reddish crystals belonging to the square prismatic system, having a specific gravity of 2°68. It is quite infusible and almost as hard as the diamond, indeed, M. Deville entertains the expectation that it may possibly be econom- ically employed for jewelling watches, and some similar purposes. Graphitic boron perfectly resembles graphite in colour and crystalline form. Silicon is capabie of existmg in similar forms. The graphite form is obtained by heating silico-fluoride of potassium with aluminium, and then dissolving out the latter with hydrochloric acid, when the silicon is left in six-sided plates. By a modification of this process, and by the use of zine it can be obtained, in regular octohedrons, sometimes of considerable size. Silicon appears to have a very remarkable tendency to combine with copper, and confers upon it a great degree of hardness, so great indeed that the alloy is to copper what steel is to iron, and may even be used for making cutting instruments. A large number of the more oxidizable metals have recently been separated and more minutely examined, and their properties found to be very different from those previously attributed to them. Their ex- amination has been greatly facilitated by the improvement in the processes for making sodium, which can now be obtained in very large quantities. It is scarcely necessary to refer to Aluminium, which is now so familiar. But Lithium, Barium, Strontium, Calcium, may be men- tioned as metals previously almost unknown, and which have recently been more minutely examined. Lithium is remarkable as being the lightest solid known ; its specific gravity is 0°589, being less than that of any known liquid, so that it floats on naphtha, and must be preserved in a vessel free from air. Barium, Strontium, and Calcium have all a Mr. J. Napier on Incrustations in Steam Boilers. 191 yellowish colour, resembling an alloy of gold and silver. ‘They are all rapidly oxidized in the air. Glucinium has been obtained by the action of Sodium upon its chloride, and Magnesium bya similar process. They are both quite permanent in the air, and can be drawn into wires and otherwise worked. Many of the other metals have been recently obtained by improved processes, but their properties are less remarkable than those already mentioned. Although the progress which has recently been made in the separation of the metals from their compounds is great, much still remains to be accomplished, and the greater number of them are still scarce and can be obtained only with great difficulty. Mr. Hennedy exhibited a collection of Crustaceans from the Shores of Millport. February 10, 1858.—Thke Prestpent in the Chair. Professor William Thomson gave an account of experiments on the Elasticity of Metals. Professor Allen Thomson exhibited and described several skulls from ancient burial places,—viz. :—1. Two skulls from catacombs near the Great Pyramid in Lower Egypt,—one of them apparently Pelasgic, the other Egyptian; 2. A skull from an ancient tomb in Malta, probably Pheenician ; 3. A skull from the excavations at Kertch, very regularly formed, and fully developed; 4. A skull from an old burial place in New Zealand. Professor Thomson compared the forms of these skulls with those of more modern races of mankind. Professor William Thomson showed an improved Apparatus for Test- ing the Electric Conductivity of Metallic Wires. February 24, 1858.—Mr. Bryon, Vice-President, in the Chair. Mr. James Napier read a paper “On Incrustations upon Steam Boilers.” On Incrustations in Steam Boilers. By Mr. James NAPIER. IyorvsTATrIon upon steam boilers is an effect so universal, that it seems to be considered a necessary consequence connected with all steam boilers, and therefore borne with as an incurable evil; and it is only when the evil is very great, and as a matter of sheer desperation, reme- 192 Mr. J. Narrer on Incrustations in Steam Boilers. dies are sought after and tried: and hence nostrums of all kinds, like quack medicines, have been poured indiscriminately into the steam boiler, as a certain cure, without the slightest reference to the nature of the evil further than the general fact, that there was a cake or crust upon the boiler or tubes. Sometimes the chemist has been called in to prescribe, and various cures have been suggested, some of which are certainly in themselves effective in preventing certain kinds of incrustation; but from subse- quent reactions, which were not foreseen, the cure in many cases became worse than the disease. I will, in the first place, refer briefly to the cause of incrustations, their nature and composition, and then to some of the remedies that have been tried and suggested, pointing out what I consider the best and most economical. If rain or distilled water alone be used for boilers, there would be no incrustation, because such water contains no salt in solution. But river and spring water always contain matters in solution, and these yield incrustation. The ordinary ingredients held in solution, in river and spring waters, are bicarbonate and sulphate of lime, iron, and magnesia, with salts of pétash and soda. In some water the sulphates prevail, and in others the carbonate, depending altogether upon the soil or rock over and through which the water flows. Rivers at a distance from towns may be very regular in composition, but near manufacturing towns the water will vary very much in quality, owing to the various soluble refuse matters let into the river. The quantity of the different salts generally found in water which can be held in solution, when the water is cold, and when boiling, is as follows, reckoning ounces of salt per gallon of water :— Cold Boiling. Sulphate of potash, : ; Wiz cpeteecas 40 oz. Chloride of sodium, . : Oar Reece ees 32 Chloride of magnesium, Se Hele) enn has 580 Carbonate of magnesia, - BO Sapcetco — Chloride of calcium, gt MAO! Ahgence wees any quantity. Nitrate of lime, . 4 J 500 desteai sou — Sulphate of lime, . ; : 4 meecoexh — Bicarbonate of lime, : Fe ie eaennede none. Carbonate of lime, » EEACE.. cesncavee — STS eee : 4 : $ eebieeste = Bicarbonate of iron : : it Se eewaerons none. Sulphate of magnesia, . : HSMN, Geiser: 120 I may remark, that some of these salts are more soluble in a solution of other salts than they are in pure water. As, for example, sulphate Mr. J. Napier on Lncrustations in Steam Boilers. 193 of lime is more soluble in a solution of common salt than it is in dis- tilled water ; and so also is common salt in solution of other salts. The quantity of sulphate of lime which boiling sea water will dissolve is not, so far as I am aware, ascertained; but from a quantity of water drawn from a boiler at Ailsa Craig, that had been fed with sea water, I found it to contain 203 grains of sulphate of lime per gallon, nearly half an ounce. Sulphate of lime is said not to be soluble in water at 300° Fah. ; but whether this would be the case in water containing salt in solution, I do not know. Bicarbonate of lime in solution in water suffers decom- position ; as the water is heated to boiling, it loses an equivalent of car- bonie acid, and passes into the state of carbonate, which, not being soluble, falls as a precipitate. In boilers where water containing carbo- nates exist, and that are allowed to stand over night, this precipitate settles on the boiler, hardens, and forms a crust. Such crusts are generally composed of thin layers, or lamine, each representing a day’s work. Bicarbonate of iron in water undergoes a similar decomposition when the water is brought to boil. Carbonic acid is evolved, and car- bonate of iron is precipitated, which is shortly after decomposed. The iron is converted into a peroxide, and the remaining carbonic acid liberated. This salt is generally in very small proportion to the lime, and only imparts to the crust formed a brownish tint. I have seen, however, a highly chalybeate water used in a boiler, which in a few weeks, when blown off the boiler, was a red colour, and gave the engine- man the impression that it was blood. A portion taken from the boiler, and allowed to settle, deposited 190 grains per gallon, containing 130 grains peroxide of iron; still no caking had taken place, nor ever took place with these waters ; but care was taken to blow off the red sediment from time to time, and regularly. Sulphate of lime in water has a different action—is not precipitated but as the water is evaporated—after it has got its maximum quantity of salt in solution—the sulphate of lime crystallizes upon the surface of the boiler, and forms that hard, crystalline cake, or scale, which adheres so tenaciously to the boiler plates. This salt constitutes three-fourths of the incrustation upon stationary or land boilers, and is the cake on all marine boilers. This sort of crust cannot be avoided by care or mecha- nical means, except by keeping the salt in the water under its crystalliz- ing quantity, which would necessitate such an amount of blowing off and supply as would render it expensive; but with the carbonates, or such salts that are precipitated, a little attention and blowing off at particular times will prevent entirely the formation of a cake or crust upon the boiler. The other salts held in solution in water are never found as crusts upon boilers; for example, I have never found a crust Vor. IV.—No. 1. 20 194 Mr. J. Naprer on Incrustations in Steam Boilers. composed of magnesia; but when magnesia had existed in the water, I have never found a crust free of that earth. The crust or cake upon fresh water boilers have generally more of a mixed composition than from marine boilers. I will add a few of these as illustration. Carbonate from Fresh Water. Carbonate of lime, . SPOON Silica, fue ; ; : SESS Sulphate of lime, . * 63 | Water, at 212°, . ened) Peroxide of iron, . aed — Magnesia, : eel 100-4 Another, from using water having sulphates in excess or carbonates— Sulphate of lime, . . 584 | Silica, . : d o eeO Carbonate of lime, . 27:3 | Carbonaceous matters, . 4:0 Carbonate of magnesia, . 5:2 <= Peroxideiron andalumina, 3:2 100°1 From a marine boiler, upon the iron plate, where care was taken in blowing off regularly, running between Aberdeen and London. Thisis a very hard, tenacious crust— Sulphate of lime, . - <9°2 )” Water: . ; : > UO) — magnesia, . 68 | Chlorine andcommon salt, 2-4 Peroxide iron and’alumina, 4:8 100-0 The next is from boiler tubes running between Glasgow and Liver- pool. In this little or no care had been taken by the engineer to pre- vent formation of crusts, which are composed of two distinct layers—the one next the tube a pure crystalline cake; that upon it was soft and granular. The two measured from } to 3 of an inch thick. These two layers separately gave— Crystalline Cake. Granular Crust. Sulphate of lime, . : : : Oi Omer orecnrecs 51:0 Magnesia, : : : : : 4:2 seeaceens 146 Silica, : : : ; : 218) SRC 2°4 Peroxide iron and alumina, . : DA ON ES 16 Water, ‘ i . : : a (59 sashes ater 15:0 Alumina, . F ‘ : : . Sie fate cba 8-4 Common salt, . < . F : Mle laceeae 2°4 Carbonic acid, . ‘ ’ : A Bee redtadaas 4°6 99°8 100°0 The next is from the same boiler tubes, working the same length of time, but every precaution and care taken by engineer. The crust was only 4 inch thick, and crystalline. Mr. J. Naprer on Incrustations in Steam Boilers. 195 Sulphate of lime, . . 94:5 | Water, . . ; im 254 Magnesia, . 3 . 15 | Salt, &c., : : wget lel Peroxide ofiron, . “ty 100:0 This shows what may be done by care; but I may mention that there was a constant blow off from the boiler to an extent of three-fourths of that boiled off as steam. So that this cake may be looked upon as being only one-fourth of that which would have been formed without blowing off. It will be seen from the specimens that the sulphate cake is crystal- line. The water, by evaporation, becomes saturated with the salt when it crystallizes; and this saturation being kept up by the supply water, these crystals grow up, not in an isolated form, but as a plate over the whole surface of the boiler, and more on those surfaces exposed to fire ; and the thickening of this plate is the extension of the crystals, which stand upon their points or axes—that is, the crystals of the plate arrange themselves in a line with the heat current, in the same manner as fused solids crystallize under the influence of rapid cooling. I will now glance at a few of the remedies proposed to prevent incrus- tation. The first is adding to the boiler a little muriatic acid. This acid will act upon carbonate of lime, and produce a very soluble salt, chloride of calcium, which will not form a cake; but it has no action upon sulphate of lime, which is the principal ingredient of boiler cake ; and besides, this remedy must be used with the utmost caution, as any excess of acid over the quantity required for the carbonate of lime will act upon the boiler, and also pass off with the steam, and corrode joints and stuffings. Indeed this remedy cannot be used with safety even under the constant superintendence of a chemist. Another universal remedy was suggested by Ritterbrandt, namely, SatammMonta. ‘This salt, put into a boiler with sulphate of lime, has no action further than rendering the sulphate a little more soluble, making it a little longer before crystallization begins ; but salammonia decom- poses carbonate of lime, producing carbonate of ammonia and chloride of calcium, both soluble salts. Should there exist any sulphates in the water, this reaction will be immediate, followed by another ; the carbo- nate of ammonia will decompose the sulphate of lime, and form carbo- nate of lime and sulphate of ammonia; but the practical defect in this case is, that whenever the carbonate of ammonia is formed it volatilizes with the steam, and destroys the buskings, and everything containing copper, and is hurtful to the tubes of tubular boilers, which are com- posed of copper and zinc. Carbonate of soda has been tried, which decomposes the sulphate of lime, producing sulphate of soda and carbonate oflime. As a precipitate 196 Mr. J. Napter on Incrustations in Steam Boilers. the difficulty in applying this salt is the regulating the quantity ; the practice has been to throw in from time to time large quantities of soda, which formed an alkaline ley in the boiler, and as soda passes freely off with steam, this practice has frustrated the object, as the alkaline steam hurt the stuffings, &e., of the engine. In a boiler treated thus, without any attention being paid afterwards, there was found at the bottom, after several months, the soda having been only thrown in once or twice at first and left to work a perpetual cure, a hard incrusted studge half an inch thick, composed of 100 parts :— Silica, : : : 2°6 | Common salt, : : 1:7 Carbonate of lime, . | 28:2 Oxide, and iron, andalum, 1:2 Sulphate of lime, . 185 | Water, : ; <4 NOTA Sulphate of magnesia, . 12°6 — Crystal sulphate of soda, 24°5 100-0 This had lain exposed for several weeks to the air before being analyzed. Soap has been tried, and is found to decompose both the carbonates and sulphates of lime. The tallow of the soap being rendered insoluble, or rather combines with some of the lime, and forms an earthy soap, which sometimes floats upon the surface of the water, forming a solid scum, preventing the escape of the steam, or causing priming, and when com- bined with much lime, it occasionally deposits and forms a very nasty erust upon the boiler. Means could be adopted to carry off the scum and recover the tallow, but its action being dependent upon the alkali it contains, it will be better to use the alkali pure. When soap is used in larger quantity than is necessary to decompose the salts in the water, priming is sure to follow. Soda and gallic acid, and tannin prenite of soda, is recently patented. Besides these, which have some chemical principle in them, I will name over the following as a proof of the haphazard system of remedies, not only suggested, but tried and advocated, and even patented :—Sawdust, potatoes, potato skins, sugar, glucose, mixture of coal tar and linseed, Castile soap and plumbago, ground dyewoods, gum, catechu, oak bark, and green vegetable matters. Such is a list of what has been tried, The effect which incrustations have upon boilers is matter of dispute. Some have boldly declared that they are not detrimental, either to the boiler or its economical production of steam; but there having been such a general feeling after a remedy, indicated by the list just given, is, I think, a practical answer to the economical question. The difficulty experienced in keeping up the steam when the boiler was covered over with a crust, has evidently led men to try anything in hopes of removing the evil; and I know that the burning of holes in boilers are often Mr. J. Naprer on Incrustations in Steam Boilers. 197 ascribed to that cause. I will not take up your time discussing the theoretical views how crusts of lime or gypsum lining the inside of a boiler must affect the transmission of the heat, but in respect to such crusts affecting a boiler, hastening its destruction, and causing danger, I refer to the recent report of the Society for the Prevention of Boiler Explosions, in which it is shown that incrustation affects the boiler. The report goes on to say— “ And lastly, I may mention among the causes of fracture, the forma- tion of a scale or certain kinds of deposits, which, by retarding the transmission of heat, also allow the plates to become overheated. The nature of these deposits, so far as regards their powers of conducting heat, appears to vary greatly ; for while some boilers, although thickly covered with scale, continue uninjured for years, others of similar con- struction, and under like conditions, with only a slight deposit, but of a different kind, require frequent repairs. On this subject there is, evidently, need of further investigation. For the prevention and removal of such deposits, various compositions have been employed with more or less success; but in the use of any composition it is preferable to effect precipitation in a tank or reservoir previous to the water entering the boiler. The employment of sediment collectors and frequent blowing off is beneficial, and should not be neglected.” Few things could show more fully the necessity of such associations than this part of the report ; and we trust that the next report will not contain a statement that certain deposits, though very thick, will do no harm, while other certain deposits, though very thin, will destroy a boiler, but will be able to say what these certain deposits are, whether belonging to the sulphates or carbonates. I have lately had my attention drawn to the whole subject as a matter requiring a little investigation, and have got a few samples of erusts to analyze, some of which I have given. Where the crust was carbonate I have found little difficulty in preventing its formation— only a little care on the part of the engineer. As we have seen, this falls as a precipitate by the mere boiling of the water. If, every night after the fire is damped down, and a little time allowed for this precipi- tate to subside, it be then blown off from the bottom, little or no incrus- tation will ever form upon the boiler. Such crust as the sample shown is always seen in nightly layers, the result of a deposit upon the boiler, which hardens and cakes by standing, and could all be removed by mechanical means and attention. And I have been told by engineers who have adopted this system of blowing off, that they do not require to clean their boilers over once a-year ; while other parties, using the same water, require to clean and chip off the crust every three months, 198 Mr. J. Naprer on Incrustations in Steam Boilers. at least. The sulphate crust, as already stated, is a crystallization upon the surface of the boiler, and cannot be removed by mechanical means. It is, however, easily and thoroughly decomposed by carbonated alkalies, the cheapest is soda. It has been already stated that the only defect in soda was its being added indiscriminately and in too large quantity—a circumstance easily avoided. I make the matter a chemical question, analyze the feed water to ascertain the amount of sulphate of lime which is present in the gallon, take the size of the boiler and quantity of feed water added per day. I then calculate the amount of carbonate of soda that will exactly neutralize the sulphate of lime in the quantity of feed water taken per day, which is dissolved in a small iron tank placed above the boiler. If the engine works twelve hours, I form a syphon that will run this soda liquor in the feed water in that time, so that at no time is there an excess of soda in the boiler, and thus the lime is converted into the state of carbonate, which precipitates, and may be removed by mechanical means of judicious blowing off, as I have de- scribed. I have only had the opportunity of trying this one boiler, using the filthy water of the Kelvin. The blowing off was not carefully attended to; nevertheless, after six weeks, the usual time of cleansing and scaling, which generally gave a crust of +s, there was nothing but a loose sludgy deposit, which was brushed off by a hard hair brush. In marine boilers using sea water, as already stated, the cake is always the sulphate crystals, although where there is no mechanical care, car- bonate crusts will also form. The use of soda in this way would be very. simple, and possibly, from their constant blowing off from the surface this carbonate of lime might be, like the salt, carried to the surface, in the first instance, and blown away while working, and would not cake upon the tubes ; but its application and effects upon sea going vessels I have had no means of testing. An analysis of sea water will not require to be made for each vessel, as with land boilers, but an average analysis may be taken. I say an average, because in different localities of the sea, and even on different days, or probably seasons of the year, the sul- phate of lime in sea water varies very much. However, this is a subject I am not yet prepared to enter into. Instead of adding the precipitate to the boiler, if mechanical means cannot throw off the precipitate entirely, then a pair of tanks in which the precipitate may be made and the boiler filled from the clear, would not be a very expensive nor unwieldy piece of apparatus, which I do not consider, however, necessary, as me- chanical means can be got for blowing off any accumulation of loose precipitates. I have now done what I had intended in my own mind, namely, to bring the subject before the Society, in hopes of drawing the attention i ots camel Mr. J. R. Napier on Voting at Limited Liability Companies. 199 of those more immediately concerned with the working of boilers. The whole subject is yet to investigate, and science, economy, and common humanity, all urge the necessity of beginning without delay. A paper was read “On a Method of Voting at Limited Liability Companies more Uniform than the present, and its Expression by a Mathematical Formula,” by James R. Napier. On a Method of Voting at Limited Liability Companies more Uniform than the present, and its Expression by a Mathematical Formula. By Jamus R. Navier. In the Joint-Stock Company’s Act, 19 and 20 Victoria, cap. 47, the thirty-eighth clause of Table B refers to the votes of shareholders as follows :— “ Every shareholder shall have one vote for every share up to ten; he shall have an additional vote for every five shares beyond the first ten shares up to 100, and an additional vote for every ten shares held by him beyond the first 100 shares.” I failed in my endeavours to discover any other reason for the adop- tion of this scale of votes than that of limiting the influence of the larger shareholders ; the limitation, however, has been done too abruptly. To make the scale vary more uniformly is the object of the present paper. The accompanying sketch shows the scale of the “ Act,’’ and the proposed modifications. The number of shares is marked along a base line according to a seale; the corresponding number of votes according to the Act is represented by the ordinates to the dotted lines ; and the proposed modi- fications, by the ordinates to the ful lines. The shares are supposed to be divided into an equi-different series, whose common difference is 4: thus, 4, 8, 12, 16, 20, 24, 28, &e., shares; and to each term of the series four votes are allotted. The sum of any number of the terms, therefore, commencing at the first, represents a number of shares, and the last term represents the number of votes. Thus, in the example above, the third term 12 represents the number of votes corresponding to the sum of the three terms, 4, 8, 12; or, in general, n being the number of terms, the number of votes will be represented by 4 n, corresponding to the number of shares represented by four times the sum of the series (1+2+3+4, &.,n) =2n(n+ 1). This expression will prob- ably be considered by the shareholders of public companies as no simplification of the present scale, but it can easily be reduced to plainer English, and nearly to the same words as those of the Act referred to, thus :— - Sjuroytmm sore pure Go oyy Se ‘OZZ OF OST Woay pue ‘OQ 04 OF Woy ‘P 04 | Wry oles OY} a[Bos O44 SOYVU JT "OV, OY} JO oBos 04} UO ooUDIAYTP yseo] OY} OpeUT FT ESNvOEG ‘; sousroyIp uomuut0d oy poqdope J ‘on ‘p ‘g ‘g ‘1 Solas OY} UI SULIO} Jo TOQuINU O19 Suroq (uv) ‘saavyg (T+) uz oy dn “({T—w) uz say 04} puosog soreys (u) £190 AF 940 A [VUOTTppe uv pur ‘soreyg (T — u) UG LOF 830A (1—“) fF avy [[eys Aoppoyoavyg AroAe ‘AT[esoUes puy é 200 Mr. J. R. Napmr on Voting at Limited Liability Companies. ‘OR ‘OR = = 9G. a.' OGG = - II = a — i aha = = 6 OF = a: = = 086 >= 08% aa = OL = = = ST OS te ae <= OB . = a ae 08d oe eae a oF 6 <7 > = | ere SSB = ar = a Le me CE a ates 8 — 7 = = ect = 2 os aa 2% at == 61 18 a = L = = = =r “Bis = SG = = ng aa Pe* o.. '00 = ia 9 x = ae = 209 = 3c . = a. oon, =— OF = -y g = as = = BOY, = #90 = er —— = aOR Ss FG = a v a7 * = = VG ae Ol < ae = ee, = aa § = ms - = #&6h gee tt) a = = — Zt —- F — ‘sorsuS G@ °° oo —_— —_ ‘Solvyg p IO} sogOA P — aa ie ‘somyg p 04 dn ‘7 4say oy} puokog oavyg 1 AtoA0 OJ JOA [BUOTIPpY UB PUL ‘oIBYS T IEF HOA T AVY TTPYS Jeppoyoreyg Araay acture LMacdonsl au Eihoacen} ber. 32 Votes (ata ee 31 Wie SHS) accor dine. =O am totes proposed, pl FOR EVERY 6 SHaRES &c. &c. war ts erly | an ; | yo we ay — a 10 Shares =, 10 Votes An aoorriomat vore FOR EVERY 2 Shares O1l2L34 6 §s 10 FOR EVERY 3 Shares Ww fiz Votes 30 13 FOR EVERY 4 Shares B45 wT JAMIE 16 Votes 36 vO - aS) ) ANAPIERS Lhe Dotted Lines represent the Files according to he Mb of Partie The Fill Lites represent. the. Vales proposed BS 20 Votes “3 19 18 FOR EVERY 5 SHARES 60 46 60 < on 2 FOR EVERY 6 SHares 66 72 s 26 | | FOR EVERY | 7 Shares ] = — : : is S4 a1 a8 106 TO PAPER ON VOTING AT JOINT STOCK COMPANIES. 25 Votes 120 SL Oo 132Vofes Mr. Epmunp Hunt on Rotatory Motion. 201 March 10, 1858.—Mr. Bryce, Vice-President, in the Chair. The following papers were read, with illustrations, by the President:— “ On the Interference of two adjacent Organ Pipes tuned to the same, or nearly the same, note.” “ On the Vibrations of Rotating Bodies.” Mr. Hunt exhibited an experiment illustrative of his paper “On Rotatory Motion;”’ but in consequence of the lateness of the hour, deferred till next meeting reading Notes in continuation of that paper. March 24, 1858.—The PrestpEntv in the Chair. Mr. John Dickie and Mr. John Dougan were elected members. Mr. Hart described some appearances of the Eclipse of the Sun on the 15th, which were not generally seen by observers in this quarter. Mr. Hart was fortunate enough to catch a momentary glimpse of the sun’s disc at the completion of the phenomenon. Mr. Edmund Hunt read, and illustrated by experiment, Notes in continuation of his paper on Rotatory Motion, which was brought before the Society on the 2d of December last. Additional Notes on Rotatory Motion. By EpmMunp Hoyt. WHEN a peg top spins on a point which experiences friction upon the supporting surface, that friction will cause the top to rise if inclined, and with the greater rapidity the blunter the point is. This effect takes place by means of a tendency to accelerate the top’s precessional motion. Supposing the top to be spinning in an inclined position upon a horizontal surface, the friction tends to make the peg roll along that surface, and this tendency acts as a rectilinear force tending to carry the top bodily along in a direction such that, if it moved fast enough the point would roll instead of rubbing on the surface. This rectilinear pressure being applied to the point of the peg, instead of the top’s centre of gravity, causes such a translation of the top combined with a rotation about its centre of gravity, that its peg moves in advance. Consequently, supposing the top to be at first inclined up towards the north, and its point to move towards the west, it will in a short time be inclined up towards the east. The rolling action will then tend to carry the top towards the north, and after a second interval it will be inclined up towards the south, and so on. In other words, the top describes a circle, and is inclined in towards the centre thereof. So far the precessional action is not taken into account. Supposing the top Vou. 1V.—No. 1. 2D 202 Mr. Epmunp Hunt on Rotatory Motion. to be rotating, so as to move (in the absence of precessional action) as just described, but with its peg point fixed, the precessional action would cause its centre of gravity to move round in the direction north, east, south, &e. This direction is the same as that of the change of inclination which the rolling tendency of the point would cause (the mere translation of the entire top not affecting the precessional action), therefore the rolling tendency must tend to accelerate the precessional motion, and consequently cause the top to rise. If the point of the top fits a hollow in the supporting surface, its friction in the hollow cannot make the top rise; but if the hollow is somewhat larger than the point, the latter will rise up the side of the hollow and move round at a determinate level ; and the friction will act as on a level surface. I exhibit a curious experiment to show that much caution is neces- sary in experimenting on the effects of friction. The gyroscope in its single ring has a bent peg fixed to the ring close to one end of the spindle. When set spinning, the instrument supports itself on the peg, the ring not turning with the fly-wheel, but merely partaking of the conical precessional motion. The friction of the pivots acting on the ring tends to accelerate the precessional motion, and thereby cause the instrument to rise; the friction of the peg point on the horizontal sup- porting surface tends to retard the precessional motion, and thereby cause the instrument to fall. If the peg rests on a soft substance, such as soft deal or caoutchoue, the instrument falls; if it rests on a hard surface, such as glass, the instrument rises. Referring to fig. 14 in the plate illustrating my iain paper :—lf a weight be fixed to the underside of the lever B, below the axis crossing the ring D, so as to lower the centre of gravity of the whole, a great variety of experiments can be shown by starting the instrument in different ways. Ifthe weight c is adjusted, so that the whole is in equilibrium with the lever horizontal ; then if the gyroscope A is raised or lowered and started with a suitable determinate impulse, its path will be a species of oval with its longest diameter vertical. The other experiments are too numerous to detail. In my former paper, I mentioned that a demonstration of the funda- mental theorem of the composition of rotatory motions was given in Airy’s Mathematical Tracts. There are other demonstrations extant, but most of them are complicated, and need the aid of spherical trigonometry. Poinsot’s method of couples perhaps affords the simplest and most elegant demonstration, but it necessitates a tedious wading through numerous preparatory propositions. I beg to offer the fol- lowing theorem as enabling us to directly apply to the case, the well known “ Parallelogram of Rectilinear Velocities.’’ It is capable of Mr. Epmunp Hunt on Rotatory Motion. 203 being put in a general form, but for the sake of simplicity, I will here give it as applicable to a sphere free to turn about any axis passing through its centre. “Ifa plane passes through a given axis of rotation the orthographic projection on that or a parallel plane, of a line repre- senting the tangential velocity of a given point on the surface, will be equal to V- sin ¢; V representing the tangential velocity of a point on the equator, and 4 the angle formed with the plane, by a line from the given point to the centre of the sphere.” It follows as a corollary that, if in a sphere two or more diametrical axes of rotation lie in a plane, the relative velocities of any point about such axes will be represented as orthographically projected on such plane by lines at right angles to the respective axes, and having the ratios to each other of the respective angular velocities; for each projection is as the corre- sponding equatorial or angular velocity multiplied by sin ¢—that is, the projections are equimultiples of the angular velocities, and having there- fore the same ratios to each other that such velocities have. Since my first paper was read, I have seen a second article by Major Barnard in Silliman’s Journal for January, 1858 ; and as in this paper the mode of showing the enlarged “cycloidal” motions is described, I think it proper to mention that I wrote three several times to the editors of S2lliman’s Journal respecting my paper, the last time on 4th December, 1857, describing the “cycloidal” experiments. I have received answers to every letter but this last and most important one. The parts of Silliman’s Journal generally reach here about the 20th of the month they are for; but that for January, 1858, was not received until the 3d March. I have thus reason to think that an account of my experiments was in America before that of the Major’s was published ; however, as far as I can learn, the experiments I exhibited before the Society on the 2d December, 1857, had not then been shown elsewhere. Major Barnard’s first paper conveys the impression that in practice, as well as theory, the gyroscope never moves horizontally—that there are always undulations, but that with high velocities they are “too rapid and too minute to be perceived.” In the second paper, however, we are told that the undulations speedily vanish, and that the gyroscope moves horizontally, or nearly so! We are not told how the undulations are made larger on mounting the gyroscope farther from the point of sup- port, nor why they are not sensible with the gyroscope arranged in the common way, as they ought to be, by the Major’s theory. He attri- butes the gradual change in the form of the curve mainly to the decreas- ing rotatory velocity of the fly-wheel. To test the correctness of this, arrange the apparatus, fig. 14, with the centre of gravity of the lever, wheel, and weight at the centre of the ring D, and set the wheel spin- 204 Mr. Epmunp Hunt on Rotatory Motion. ning, with the lever horizontal. If now a vertical impulse is imparted to one end of the lever, the wheel will describe a circle; if the Major’s view is right, this circle should become larger and larger; on the con- trary, however, the circle becomes less and less, owing to the action of the centrifugal resultant. I believe the decrease in the rotatory velo- city of the fly-wheel would of itself tend to make the curves more prolate, but not in the way shown by Major Barnard, nor to anything like the extent actually seen in practice. In his first paper Major Barnard endeavours to show that the undu- latory motion is such as would be produced by the combined action of gravity, and what he terms a deflecting force. Supposing there is such a deflecting force, it will be directed to a point travelling along the level of the cusp of the cycloidal curve; in the supposed case in which the rotatory velocity continues uniform, and the cusped cycloid is described, this point travels at such a rate as to coincide with the point describing the curve at each cusp; but when the rotatory velocity decreases, the point travels faster; so that on its reaching the point at which the cusp would have occurred, the gyroscope is below it, instead of coincident with it, and the curve is deflected, as shown at a, (fig. 1, Major Barnard’s second paper). The mean motion along the curve is in a certain sense independent of the mean horizontal angular motion— that is, the motion of the point to which I have supposed the “ deflect- ing force” to be referred. If the motion along the curve is retarded (which can be done by imparting a forward horizontal impulse), the motion of the “ deflection”’ point is more rapid in comparison, and the curve described is prolate. On the other hand, if the motion along the curve is sufficiently accelerated, the gyroscope will get in advance of the “‘ deflection”’ point, rise above it, and form a loop round it. The intro- duction of the idea of a “ deflecting force” facilitates the conception of the way in which the curves are modified ; but I think Major Barnard unnecessarily mystifies it. This deflecting force simply corresponds to the radial pressure on the point of support in the case of the ordinary pendulum. What corresponds to the point of support in the common pendulum is in the gyroscope what I have termed the precessional axis, which is continually moving round. In the common pendulum, the bob is at each instant moving in a direction at right angles to the line between it and the point of support ; and similarly the gyroscope is at each instant moving at right angles to the plane between it and the imaginary precessional axis. In my former paper I have endeavoured to explain actions having a much greater influence on the form of the curve than the mere decrease in the rotatory velocity of the fiy-wheel. Mr. Epmounpv Henv on Rotatory Motion. 205 At page 70, Major Barnard says—‘“ This sustaining power being directly proportional to the rotatory velocity of the disc, as well as to the angular velocity of the axis, diminishes with the former; and as it diminishes, the axis must descend, acquiring angular velocity due to the height of fall; hence the rapid gyration and the descending spiral motion which accompanies the loss of rotatory velocity.” This sentence contains several errors: in the first place, theoretically, the sustaining power is absolute for all rotatory velocities—that is, the gyroscope always retains or recovers its original elevation, whatever the rotatory velocity may be; secondly, the descent of the axis is entirely due to the resistance experienced to the precessional motion ; thirdly, the angular or precessional velocity increases as the rotatory velocity de- creases, and there cannot be any increase of it due to the descent; if an undulatory curve is being described, the descent will make it more prolate; but any tendency to increase the precessional motion will immediately check the descent. At page 75, Major Barnard speaking of the top, says—“ This rolling speedily imparts an angular motion to the axis, greater than the hori- zontal gyration due to gravity’’—(there is a tendency to increase the gyratory motion, but it takes effect in lifting up the top; the gyratory or precessional motion cannot be increased, unless the top is in some way prevented from rising). “The deflecting force becomes in excess and the top rises.” Also, page 71,—‘'The addition to this gyratory velocity, caused by friction, when the axis is inclined wpwards, puts the deflecting force in excess, and the axis is raised.”’ Here we have the mystical “deflecting” force figuring in quite a new way. If we do assume that a “deflecting force’? acts in producing the undulatory motion, we cannot consider it as doing more than altering the direction of motion, just as the connection between the pendulum bob and its point of support makes the former move in acurve. If an undulatory curve is being described, any additional forward impulse merely makes the curve more prolate ; if the gyroscope or top is moving horizontally there is no “ deflecting force ” in action, so that it cannot be excess of that which causes a rise. In either case, the rise is derived from the horizontal impulse in precisely the same way as the horizontal gyratory or precessional motion is derived from the downward pressure of gravity. At page 74, Major Barnard says—* But these little undulations speedily disappear, through the retarding influence of friction and resistance of the air.’’ In the case in which the top point is so free from friction that the centre of gravity remains always in the same vertical line, that friction must be quite unable to make the undulations disappear. As to the resistance of the air doing so, the top may be so 206 Mr. James Naprenr’s Analysis of Stone fused by Lightning. proportioned as, ceteris paribus, to increase that resistance, and to make the rotatory velocity decrease more rapidly (namely, by, amongst other alterations, placing the rotating mass at a greater distance from the point), but the curves will be larger and continue longer—instead of the reverse, as Major Barnard would lead one to expect. Specimens of Silicon, Boron, and some other rare elements, were exhibited by Dr. Anderson. Mr. Keddie read the following analysis by Mr. James Napier, chemist, of a small portion of the stone fused by lightning, in May, 1854, exhi- bited at the meeting of the 27th January. The stone, which was a fragment of one of the turrets of the tower of Glencairn Parish Church, was given to Mr. Keddie by Robert M‘Turk, Esq. of Hastings Hall, Glencairn, and is now deposited in the Museum of the Andersonian University :— “JT took a small sample of the fused stone, and also a piece of the stone not fused, apd submitting them to analysi,s obtained the following results :— Original Stone. ‘¢ Silica, ‘ : 5 F F Z 88°5 Peroxide of iron, . A F 4 2:5 Alumina, . : 5 ‘ : 4°5 Carbonate of lime, . : 3 : 2°5 Magnesia, - ; : : : 1:0 Moisture, : 5 : : . 1:0 100:0 “The fused stone was a fair glass, opaque and brittle, indicative of rapid cooling. “The analysis gave— “ Silica, ; . : 4 : : 84°3 Protoxide ofiron, - : d ‘ 2°9 Alumina, ; ; ; : : 4:8 Lime, , 4 : F 0 : 3:2 Magnesia, c 3 3 : : 1:6 1000 “The only change is the reduction of the peroxide of iron to the state of protoxide. There is also more lime, iron, and magnesia; but this may be accounted for by the sample of the stone that I took, being from the outside, having lost these ingredients from being exposed to moisture or rain,—these being the matters that would be dissolved out of stone by the access of water. The analysis is interesting as showing how rapidly chemical action must have taken place.” Report on the Progress and State of Applied Mechanics. 207 April 7, 1858.—Mr. Bryon, Vice-President, in the Chair. A Report was read from the Committee ‘“‘On Applied Mechanies,”’ consisting of Mr. James Robert Napier, Mr. Walter Neilson, and Professor W. J. Macquorn Rankine. Report on the Progress and State of Applied Mechanics. By Jamus Rosrerr Naprer, Jron Shipbuilder; Waren Neiison, Mechanical Engineer ; and W. J. Macquorn Ranxinz, LL.D., Civil Engineer. 1. Tux subject of Applied Mechanics, including, as it does, every application of the laws of force and motion to works of human art, is so extensive and multiform, that a mere enumeration of all its branches and subdivisions, and of the various objects to which they relate, would, if complete and fully detailed in every respect, occupy more time than ean be devoted to a Report like the present, All that your Reporters ean pretend to accomplish, is to give to the best of their ability a general view of the recent progress and present state of this vast division of human knowledge and practice, with such illustrations and examples as their own experience and study may most readily suggest to their minds. 2. The objects to which Applied Mechanics relate may, in the first place, be divided into two great classes: SrRucTURES and MacuinEs;— Structures, whose parts are intended to remain fixed relatively to each other, and whose requisites are—Stability, which preserves the relative positions of the parts of a structure, and Strength, which preserves their figures, connection, and continuity; and Machines, whose parts are intended to move, and to perform work, and whose requisites are, not only strength in each separate moving piece, and stability in the frame (which is itself a structure); but Lficiency, which consists in the adaptation of the moving power to the work to be performed. 8. Certain objects, such as carriages and ships, may be considered to belong to both classes—being regarded as structures with respect to the connection of their parts, and as machines with respect to their means of propulsion. 4. Each separate part of a machine, being required to preserve its figure and continuity under the forces to which it is exposed, is itself a structure, and subject to the principles which regulate strength and stability. 5. Thus, Applied Mechanics, regarded as a science, may be divided into Trcrontcs and Exrraurics, corresponding respectively to the two 208 Report on the Progress and State of Applied Mechanics. divisions of Construction and MrcuantsM, of which it consists when regarded as an art. ‘ 6. In the perfecting of Applied Mechanics, whether as a science or as an art, the end aimed at, and the criterion by which true is to be dis- tinguished from false progress, may be expressed by the word Economy ; that is, the production of every desired effect by those means which are exactly adequate to produce it, and no more. Whether in structures or in machines, the proportion borne by the means exactly adequate to produce an effect, and the means actually employed, can be expressed by numerical ratio. For pEeRFEcT Economy, that ratio is Uniry; but perfect economy never is, nor can be attained in human works ; and in them the economy realized is expressed by some fraction, falling short of unity by a quantity which expresses the waste of means. Theory strives to ascertain, by experiment and by reasoning, the exact amount and causes of waste, and how it is to be reduced; and practice strives, by continually improving skill, to effect that reduction ; and both tend to bring the fraction that denotes actual economy, continually nearer and nearer to that UNIT, which expresses the unattainable, though not unapproachable, limit of the result of human efforts. 7. In a Structure three things are to be considered ; its materials,— the mode of putting them together,—and the purposes for which the structure is to be used. 8. The materials of structures are inorganic and organic. Inorganic materials are for the most part either stony or metallic. Organic ma- terials are of vegetable or animal origin. 9. With regard to natwral stone, the chief improvements which have of late years been made, have been in the art of separating it from its native rock by blasting. Much skill is employed in the placing of mines so as to detach large masses of it with the least possible waste of powder and of stone; and the heat generated by currents of electri- city in metallic wires, has for many years been advantageously employed to fire the charges at one instant. Some of the most remarkable operations of this kind, of recent date, are described in a paper read by Mr. Sim (manager of the granite quarries at Furnace) to the British Association at Glasgow, in 1855. 10. The transport of good building stone from a distance is a matter of importance to those places where it is deficient. Thus, in those parts of the south of England where the formation is chalk, and the only stones fit for building that are found on the spot are the flints imbedded in the chalk, a valuable article of commerce is the oolite which is imported from quarries in Normandy, and which though soft when first quarried, and capable of taking the most delicate carving Report on the Progress and State of Applied Mechanics. 209 from carpenters’ tools, hardens by exposure to the air, so as to become strong and durable. The beautiful parish churches of Kent and Sussex, in whose walls a concrete of flints fills the intervals between the carved stone quoins and arches, show that at an early date the Normans imported the stone of their province into the south of England; but that impor- tation ceased for a long time, and has only been of late years revived. 11. Of Artificial Stones, the most useful, though not the most costly, are BRICKS. The art of making bricks, of regular figure and great strength and durability, was brought to great perfection by the Romans, and subsequently to their time it appears to have been much neglected and forgotten, until of late years skill has been devoted to it with much success. Bricks have been moulded by hand or by mechanism, of various, convenient, and ornamental shapes; they have been made of great strength and accuracy of figure, by compressing dry clay; but the most useful improvements are those which have been made in the strength and durability of common bricks, by good materials and careful work- manship; and of this some of the most remarkable examples are 'to be found in Glasgow and its neighbourhood, where the frequent occurrence of large and lofty structures of brick, and especially of furnace chimneys, (one of which, that of St. Rollox, is, with three exceptions, the highest building in the world), renders strength and durability absolutely ne- cessary in bricks. 12. Connected with the manufacture of bricks, is that of clay and earthenware pipes, for drainage and water-supply; an art of recent origin, and very beneficial, by its enabling small channels for the con- veyance of water, to be executed at a cost proportionate to their size. 13. Amongst artificial stones may be classed mortars and cements ; and of these the most important are such as harden readily in a moist atmosphere, and under water. Hydraulic Limes and Cements, as they are called, though much used by the ancients, especially the Romans, were in former times comparatively rare and costly, because the quantity in which they could be produced depended on the finding of certain natural stones; but now the researches of Pasley and Vicat have fur- nished us with the means of producing artificially, by the combination of lime with silica and alumina, or with oxide of iron, in proper pro- portions, hydraulic mortar and cement in any quantity that may be required. 14. One of the most useful artificial stones is concrete: a mixture of lime with gravel, and with fragments of stone. Though much employed by the Romans, and by Medieval builders, its proper composition and use appear to have fallen for a time into neglect, until of late years it again received the attention of engineers, The great sea-wall at Vou. IV.—No. 1. 25 210 Report on the Progress and State of Applied Mechanics. Brighton, built wholly of a concrete of lime and flints, has for many years stood exposed to the full force of the waves of the English Chan- nel. Blocks of concrete, hardened in boxes, have been used for the building of piers and breakwaters. Many bridges have had their piers founded in difficult positions, on platforms of concrete, which possess in some respects the properties of large flat blocks of solid stone; and, in particular the new bridge of Westminster, designed by Mr. Page, and now approaching completion, has the foundation and lower portion of each of its piers formed of a mass of concrete, contained in a cast iron casing. 15. Amongst various artificial stones, too numerous to specify in detail, mention may be made of the artificial sandstone of Mr. Ransome, composed of grains of sand cemented together by a sort of glass, and very useful in places at a distance from good natural sandstone, and also of a method invented by Mr. Kuhlmann, of hardening soft stones by infiltration with a solution of silica. 15 (a). Guass itself is a kind of artificial stone. Its employment as the principal part of the covering of a building, originated with the great Exhibition of 1851. Its use for such purposes has been much facilitated by the invention of processes for easily manufacturing it in large flat sheets. 16. Bituminous or Asphaltic Cements, which, though of organic origin, are not organized, appear to have been used in Western and Central Asia, in ages beyond the range of history. The most remarkable use which has been found for them in modern times, is the binding together of the broken stone, gravel, sand, or other hard materials, with which roadways are covered. ‘This art has hitherto been brought to greater perfection in France than in Britain; but it is to be hoped that by perseverance, we shall in time be enabled to equal or to excel our neigh- bours. 17. Amongst the Merats, the first place for abundance, for utility, and for strength, belongs to Iron. The progress which has in recent times been made in its production, has been in quantity rather than in quality. In times, and by nations, that we consider barbarous, iron and steel have been produced of a strength, toughness, and elasticity, which we should find it difficult to equal. Our present superiority consists mainly in the power of producing iron in abundance, sufficient to meet any demand which its rapidly increasing use in every kind of structure and machine may cause ; and the great improvements which, in the course of the present century have taken place in the manufacture of iron, have tended chiefly to increase the rapidity and diminish the cost of its production. Report on the Progress and State of Applied Mechanics. 211 18. Nevertheless some inventions have been carried into effect, whose tendency is to improve the quality of iron by increasing its strength, such as the smelting of iron by coke deprived of sulphur by the process of Mr. Calvert, whereby one of the most weakening impurities is re- moved,—and the mixing of wrought iron with cast iron, to produce a metal tougher than ordinary cast iron, invented by Mr. Morries Stirling. The effect of repeated meltings on the strength of cast iron, has been tested by Mr. Fairbairn, who found the iron increased both in tenacity and in hardness, by each melting up to the twelfth ; while, for meltings beyond the twelfth, the iron, though its hardness is increased, becomes brittle. 19. The process of Mr. Bessemer, for puddling iron by a blast of air, although it has been found to answer perfectly with the iron of Nova Scotia, has not hitherto succeeded with that of Scotland and of Stafford- shire ; and until further experiments have been made, it is impossible to state what its results in most cases may be. 20. One of the greatest improvements ever made in the manufacture of STEEL, was that effected by the use of carburet of manganese, or of carbon and manganese separately added: a source of immense benefit to all manufacturers and users of steel,—but of ruin to its inventor, the late Mr. Heath. 21. Various improvements, too numerous to mention in detail, have of late years been made in converting iron into steel, case-hardening, moulding, casting, shingling, rolling, forging, welding, rivetting, and other processes applicable to cast and wrought iron, and to steel. An important instrument in those improvements which relate to the manu- facture and forging of wrought iron, has been the steam hammer: whether the original steam hammer of Nasmyth, in which the hammer is attached to the piston, or the later steam hammer of Condie, in which the piston is fixed and the cylinder carries the hammer. It is by such an implement alone that such forgings can be executed as the engine, paddle, and screw-shafts of the Great Eastern. 22. Next to iron in abundance and utility, and also in strength, is COPPER ; along with which may be considered its alloy with zinc, the ordinary brass, and with tin, also known as brass, but more properly called bronze, and classed, according to the proportion of its constitu- ents, into gun-metal, bell-metal, and speculum-metal ; the first, which contains most copper, being the softest and toughest ; and the last, which contains most tin, being as brittle as glass. Modern chemistry has shown the necessity of combining the constituents of each of those alloys in atomic proportions, in order that the compound metal pro- duced may be uniform in structure, and free from flaws, and that according to its purposes, it may be strong, sonorous, or brilliant. 212 Report on the Progress and State of Applied Mechanics. 23. Organic materials of construction are of vegetable or of animal origin, and are generally fibrous, like wood and leather; but exceptions to this are found in caoutchouc and gutta-percha. 24. The available sources of TIMBER have of late been much increased by the discovery of the useful properties of the trees of various distant and lately settled countries,—such as the various Eucalypti of Australia, some of which are remarkable for size and strength. Central and South America also,—Africa, Ceylon, and other tropical regions, possess many timber trees remarkable for strength, durability, and beauty, whose properties have only recently become known to Europeans. On these points, interesting information may be obtained from the report of Captain Fowke, R.E., on the specimens of timber at the Paris Exhibi- tion of 1855. 25. In the treatment of timber, the points of principal importance are seasoning and preservation. SrasonrnG, which consists in the evaporation or extraction of the moisture contained in the timber, to such an extent as to prevent warping or decay from the presence of that moisture, used formerly to be effected by spontaneous drying in the open air, and occupied from two to four years: and when attempts were made to hasten the process, or to render it more effective by artificial means, these consisted in steeping, boiling, or steaming, which saved but little time, and weakened the timber. But within the last few years it has been discovered, that by exposing timber to hot air in an oven, it can be as completely dried in a few days as formerly in two, three, or four years. An example of this process may be seen at the yard of Messrs. R. Napier & Sons, at Govan. It is unnecessary to enlarge upon the economy which it effects in time and money. 26. The PRESERVATION OF TIMBER, by filling its pores with antisep- tic fluids, has occupied the attention of various inquirers for nearly half a century. Amongst the earliest substances employed with success, was a solution of sulphate of iron ; more recently, a solution of bichlo- ride of mercury was employed, as well as various other metallic salts. The saturation was at first effected by simple steeping, then by pro- ducing a partial vacuum by the condensation of steam in a receiver at one end of the log, while the pressure of the atmosphere forced the solution into the vessels at the other end; and lately, a method has been invented of forcing the solution by hydrostatic pressure into the vessels at one end of the log, so as to expel the sap at the other end, and saturate the log with the solution. Good success has attended the use, as a fluid for preserving timber, of a kind of pitch-oil, called in commerce “ creosote,” (although differing from the creosote of chemists), which not only prevents decay, but repels the various animals commonly Report on the Progress and State of Applied Mechanics. 213 called “sea-worms,”’ whose burrowing would otherwise reduce most immersed pieces of timber to the condition of a honeycomb. 27. The discovery of new FIBROUS VEGETABLE SUBSTANCES, in addi- tion to those already known, occupies the attention of many naturalists. 28. Few materials have contributed more, by their discovery, to the advancement of practical mechanics than IypIA-RUBBER and GuTTa- PERCHA ; and especially the compound of the former substance with sulphur, called Vutcantzzp INDIA-RUBBER, which, by the perfection of its elasticity, the great variations of form that it is capable of undergo- ing, and its preservation of those properties throughout a great range of temperature, is equally well adapted to act as an extensible spring, and as a compressible cushion, to prevent shocks between hard surfaces. GurtTa-PERCHA, though softened by a moderate degree of heat, possesses - a strength and an elasticity, at ordinary temperatures, which enable it to be employed as a substitute for leather belts in machinery. Its recent application to the coating and insulating of telegraph-wires, is well known. 29. A new process of dressing leather was introduced a few years ago, by which its strength is rendered much greater than it formerly was ; and it is better fitted for supporting heavy loads, and transmitting intense forces in machinery. 30. As an artificial substitute for natural fibrous material, may be noted the WrreE-ropes of Smith and of Newall; and the wire-cables, applied to suspension-bridges, by Roebling and other engineers, in which the flexibility of a fibrous material is combined with strength greater than is possessed by any animal or vegetable fibre. In most suspension-bridge cables, the wires are parallel ; but in wire-ropes, they are spun into a spiral form, by an apparatus which makes them revolve round each other without turning about their own axes,—so that each wire, although it is bent into a screw, is not twisted,—a condition essential to the preservation of the strength of the wires unimpaired. 31. The arr or PUTTING TOGETHER the materials of structures, requires for its accomplishment the observance of two kinds of princi- ples,—those of stanrirry and those of streneru. Stability insures that the pieces, of which the structure is made up, shall preserve their proper positions, without being upset or dislocated ;—strength, that each piece shall preserve its figure, and remain whole under the utmost load that is to be laid on it. The theory of stability forms a branch of the science of statics, depending for its advancement on the application of mathematics to questions whose experimental data are few and simple, such as the weights of bodies, and the friction between their surfaces ; the theory of strength, depending on mathematical investigation also, 214 Report on the Progress and State of Applied Mechanics. is based on experimental data, in some cases of great intricacy and obscurity, of which our knowledge is in many respects imperfect, and which are in the course of being augmented every day. 32. The principles of stability, especially as regards masonry, were well understood by the Romans and by the Medizval architects. The beauty of architecture depends, to a great extent, upon their observance. Amongst the contributions that have of late been made to our know- ‘ledge of them, may be mentioned the researches of Mr. Moseley, on the Stability of Structures; and those of Mr. Yvon-Villarceaux, on the Stability of the Arch (published in the Memoires des Savants Etrangers, vol. xii). The latter paper contains the first complete mathematical investigation of the conditions of equilibrium of an arch, under fluid pressure, which are also those of many arches, under a solid pressure ; and the manner in which the solution is obtained by means of elliptic functions, is such as must inspire every mathematician with admiration. The results, when applied to practice, are likely to conduce materially to the stability, economy, and beauty of large stone bridges. The theory of the stability and pressure of earth has recently been reduced to a system based on the sole law of the proportionality of the friction to the pressure, without any of the “ mathematical artifices’’ hitherto employed ; and a principle, called that “ of the transformation of struc- twres,” by means of which, when a structure possessing stability has been designed, the figures of an indefinite number of other structures, also possessing stability, can be deduced from it by projection, may be expected to prove of some utility. 33. A mere catalogue of the names of those who have contributed, by their labours, to our knowledge either of the mathematical theory of the STRENGTH OF MATERIALS, or of its experimental data, would occupy a considerable time in being read. Your Reporters, mentioning only those who at present occur to their remembrance, have to name Galileo, Leibnitz, Huyghens, Hooke, Boyle, Newton, the Bernouillis, Euler, Boscovich, Coulomb, Belidor, Vince, Dupin, Marriotte, Smeaton, Robison, Musschenbroek, Young, Rennie, Bevan, Tredgold, Rondelet, Telford, Brewster, Fresnel, Gauss, Savart, Chladni, Navier, Poisson, Oersted, Colladon, Sturm, Mossotti, Cauchy, Lamé, Clapeyron, Grassi, Regnault, Wertheim, Chevandier, Carillion, Kirwan, St. Venant, Ponce- let, Yvon-Villarceaus, Morin, Green, Stokes, M‘Cullagh, Haughton, Kelland, Dunlop, Fincham, Mushet, Pasley, Brown, Brunel, Hodgkin- son, Fairbairn, Stephenson, Clark, P. Barlow, P. W. Barlow, W. H. Barlow, Couch, Smith, Dobson, Galton, James, Daniell, Wheatstone, Watson, Kupfer, Forbes, Gordon, William Thomson, James Thomson, Jellett, Maxwell, Mallet, Russell, Fowke, Mendis. Report on ihe Progress and State of Applied Mechanics. 214 34. Toe MATHEMATICAL THEORY OF STRENGTH is a branch of the general theory of elasticity; and when that general theory is strictly applied to such problems as occur in practice, the mathematical expres- sions arrived at are so complex, that they have been exactly solved in but a few cases, and are in general too elaborate for practical use. It therefore becomes one of the functions of mathematicians who study this branch of mechanics, to seek for approximate solutions of the problems that it presents, which shall be sufficiently simple to be used as practical rules, without incurring too great a sacrifice of exactness. A remarkable example of success in this, is furnished by M. de St. Venant’s investigations upon the torsion of bars, other than circular in section. 35. Amongst recent experiments on the strength of stone which have been made generally public, are those of Messrs. Wheatstone and Daniell, on specimens of stone prepared for the building of the Palace of Westminster. It is the practice of many architects and engineers— and it ought to be the practice of all—to test, by experiments, the stone proposed to be used in every building of importance. Mr. Alex- ander J. Adie’s experiments on the expansion of stone and brick by heat, published some years ago in the 7’ransactions of the Royal Society of Edinburgh, furnished data which are indirectly of importance as regards the strength of structures. 36. The principal sources of information respecting the strength of tamber, and especially of those kinds which are most commonly employed in Europe, continue to be the experiments of Professor Barlow, as re- corded in his work on the Strength of Materials, and (with the addition of some experiments by Tredgold and others), in Z'redgold’s Principles of Carpentry. The most important additions recently made to the information afforded by these works, have been the experiments of Mr. Hodgkinson on the resistance of timber to crushing,—those of Captain Fowke, on the specimens of timber at the Paris Exhibition of 1855,— and those of Mr. Adrian Mendis, on the Timber Trees of Ceylon. 37. The information collected in the standard work of Tredgold, on the Srrenetn oF Inon, received, a few years ago, most valuable additions from the experiments of Mr. Hodgkinson, who ascertained the great: difference which exists between the strength of cast iron to resist direct crushing and direct tearing—the former being about six times the latter—a fact of the highest practical importance. Mr. Hodgkinson also ascertained the mode of variation of the resistance of east and wrought iron pillars to a vertical load, and represented its law by a formula. Mr. Lewis Gordon has since shown, in a paper read to the Philosophical Society of Glasgow, that the results of Mr. Hodgkin- 216 Report on the Progress and State of Applied Mechanics. son’s experiments are capable of being accurately represented by suitably modifying the constant multipliers in a formula originally proposed by Tredgold ; and this formula indicates the fact, that for a pillar whose length is less than twenty-seven or twenty-eight times its diameter, cast iron is the stronger material,—while, for a pillar whose length is greater in proportion to its diameter, wrought-iron is the stronger. To Mr. Hodgkinson is due the experimental investigation of the resistance of wrought iron tubes to a direct longitudinal thrust, and of the manner in which all granular substances give way to a direct crushing force, by splitting into wedges, cones, and pyramids, of a certain inclination for each material. 38. The resistance of wrought iron rivets to shearing, has been determined by Mr. Doyne (who commanded the Army Works Corps in the Crimea), and found to be nearly equal to the tenacity of boiler- plate. 39. The experiments which have recently contributed most to the advancement of our knowledge of the strength of iron, are those of Mr. Fairbairn. By him was invented that cellular construction, which enables wrought iron plates to withstand a thrust, and is essential to the practicability of those tubular girders large enough to transmit a train, the original idea of which was the invention of Mr. Stephenson. Mr. Fairbairn has determined the strength of iron at different tempe- ratures (showing it not to be impaired at 600° F.), the strength of cast iron, after repeated meltings,—the strength of various kinds of plate iron, ‘along and across the grain,—of various forms of plate and bar iron beams,—of different forms of boilers,-—and of the different parts upon which the strength of a boiler depends, so that the giving them their proper proportions is now a matter of calculation. Many of Mr. Fair- bairn’s experiments have been made at the instance of the British Association ; and, amongst others, those which have just been com- pleted upon the resistance of thin tubes, such as the flues of boilers, to a pressure from without, tending to make them collapse. 40. Mr. W. H. Barlow, experimenting on the resistance of CAsT AND WROUGHT IRON BEAMS to a TRANSVERSE LOAD, has recently found that resistance to be greater than that which corresponds to the direct tenacity of the material, in a proportion depending on the figure of the cross-section of the beam,—being greater as that figure becomes more compact, and approaches a solid rectangular shape. When a solid rectangular cast iron beam is broken under a transverse load, Mr. Barlow finds that the tension upon those particles which are most strained, viz.,—those at the middle of the lower side of the beam, is about two-and-a-half times as intense as the tension which tears a bar Report on the Progress and State of Applied Mechanics. 217 of the same cast iron asunder directly. Mr. Barlow calls the additional resistance which he has discovered, resistance of flexwre, and has framed an ingenious theory of the manner in which it is produced. It is possible, however, that it may arise altogether from the superior strength of the skin of the iron, as compared with that of the interior of the mass ; for experiments on direct tension show the tenacity of the interior, in the very centre of the mass, where it is weakest, while experiments on the cross-breaking of beams show the tenacity of parts of the mass, either at or near the skin. But be the cause of the addi- tional resistance what it may, its discovery is one of the highest impor- tance. It is described in two papers, published in the Philosophical Transactions for 1856 and 1857. 41. Dr. William Thomson, in the course of the present year, with the assistance of two students of his class, discovered a kind of resis- tance in elastic solids, analogous to friction, inasmuch as it retards, without finally preventing, both the strain produced by the application of a load, and the recovery from that strain when the load is removed. 42. The processps oF ConstRucTIoN, employed in the making of structures, depend on the nature of the material, and may be classed into Larthwork, Masonry, Carpentry, and Metal-work. 43. The unparalleled magnitude of the Hartuworks, including excavations, embankments, shafts, and tunnels, required for the Rail- ways, which for more than a quarter of a century have been extending over the world, have naturally led to an increase of skill in the practical details of the operations by which they are executed ; but it would be difficult to point out many specific inventions by which those operations have been improved, except some ingenious machines for digging earth and tunnelling in rock, which have been introduced to a limited extent. It may be mentioned as an interesting fact, that the cost of the ordinary earthwork of Railways, per cubic yard, is nearly the same all over the world, the differences in the wages of the excavators being compensated by the differences in their efficiency. For example, it is stated, that on the East Indian Railway, where the excavators’ wages are about one- twelfth of the wages in Britain, twelve times as many excavators are required to do the same quantity of work, and the result is, that the cost of the earthwork is nearly equal in both regions. 44. Connected with the subject of earthwork, is that of rounDA- gions. ‘The gradual extension of the use of concrete, in foundations on soft ground and under water, has already been referred to. A useful method of making foundations for heavy structures, such as viaducts, on soft ground, of great depth, is to sink cylindrical wells, lined with brickwork or ashlar masonry, resting on a drum-curb, which is lowered Vou, 1V.—No, 1. 25 218 Report on the Progress and State of Applied Mechanics. by undermining it from within, while the building of the lining is con- tinued at the top, until a firm stratum is reached, when the well is filled with concrete, or arched over; so that each well forms a pillar, resting on solid ground ; and on a sufficient number of such pillars, suitably placed, the superstructure can be erected. This method has been fol- lowed with success on the Indian railways. 45. A method of making FOUNDATIONS IN WATER AND MUD, first introduced at the new bridge over the Medway at Rochester, is now coming into extensive use. A vertical cast ironpipe, extending from the bottom to about nine feet above the surface of the water, and large enough for men to work in, is bolted together in lengths, with internal flanges; and on the top is bolted a cast iron bell, having within it a box with double doors for entrance and exit, and a windlass and platform.