PHILOSOPHICAL

TRANSACTIONS,

OF THE

ROYAL SOCIETY

OF

LONDON.

FOR THE YEAR MDCCXIX.

PART I.

LONDON1

PRINTED BY W. BULMER AND CO. CLEVELAND-ROW, ST, JAMES'S; AND SOLD BY G. AND W. NICOL, PALL-MALL, BOOKSELLERS TO HIS MAJESTY, AND PRINTERS TO THE ROYAL SOCIETY.

MDCCCXIX. C iii 3

ADVERTISEMENT.

1 HE Committee appointed by the Royal Society to direct the publication of the PhilosophicalTransactions, take this opportunity to acquaint the Public, that it fully appears, as well from the council-books and journals of the Society, as from repeated de- clarations which have been made in several former Transactions, that the printing of them was always, from time to time, the single act of the respective Secretaries, till the Forty-seventh Volume: the Society, as a Body, never interesting themselves any further in their publication, than by occasionally recom- mending the revival of them to some of their Secretaries, when, from the particular circumstances of their affairs, the Transactions had happened for any length of time to be intermitted. And this seems principally to have been done with a view to satisfy the Public, that their usual meetings were then continued, for the improvement of knowledge, and benefit of mankind, the great ends of their first institution by the Royal Charters, and which they have ever since steadily pursued. But the Society being of late years greatly enlarged, and their communications more numerous, it was thought advisable that a Committee of their members should be appointed, to reconsider the papers read before them, and select out of themnsuch as they should judge most proper for publication in the future Transac- tions; which was accordingly done upon the 96th of March, 1752. And the grounds of their choice are, and will continue to r iv 3 be, the importance and singularity of the subjects, or the advan- tageous manner of treating them; without pretending to answer for the certainty of the facts, or propriety of the reasonings, contained in the several papers so published, which must still rest on the credit or judgment of their respective authors. It is likewise necessary on this occasion to remark, that it is an established rule of the Society, to which they will always adhere, never to give their opinion, as a Body, upon any sub- ject, either of Nature or Art, that comes before them. And therefore the thanks, which are frequently proposed from the Chair, to be given to the authors of such papers as are read at their accustomed meetings, or to the persons through whose hands they received them, are to be considered in no other light than as a matter of civility, in return for the respect shewn to the Society by those communications. The like also is to be said with regard to the several projects, inventions, and curiosi- ties of various kinds, which are often exhibited to the Society; the authors whereof, or those who exhibit them, frequently take the liberty to report, and even to certify in the public news-papers, that they have met with the highest applause and approbation. And therefore it is hoped, that no regard will hereafter be paid to such reports and public notices; which in some instances have been too lightly credited, to the disho- nour of the Society. CONTENTS.

I. The CroonianLecture, On the conversionof Pus into gra- nulations or new Flesh. By Sir , Bart. V.P.R. S. p. 1 II. On the Laws whichregulate the Absoiptionof polarisedlight by Doubly RefractingCrystals. By , LL.D. F. R. S. Lond. and Edin. In a Letter addressedto the Rzght Hon. Sir Joseph Banks, Bart. G. C. B. P. R. S. p. i1 III. Observationssur la decompositionde l'amidona la tempera- tureatmospherique par l'action de l'air et de l'eau. Par Theo- dore de Saussure, Professeurde Mineralogiedans I'Academie de Geneve, Correspondantde l'Institut Royal de France, &c. Communicatedby Alexander Marcet, M. D. F. R. S. p. 29 IV. On CorporaLutea. By Sir Everard Home, Bart. V. P. R. S, P. 59 V. Remarkson the probabilitiesof errorin physicalobservations, and on the density of the earth, considered,especially with regardto the reductionof experimentson the pendulum. In a letter to Capt. , F. R. S. By Thomas Young, M. D. For. Sec. R. S. p. 70 VI. On theanomaly in the variationof the magneticneedle as ob- servedon ship-board.By William Scoresby, jun. Esq. Com- municatedby the Right Hon. Sir Joseph Banks, Bart. G. C. B. P.R. S. p. 96 VII. On the genus Ocythoe; being an extract of a letter from Thomas Say, Esq. of Philadelphia, to Win. Elford Leach, M.D. F. R, S. p. 107 vi

VIII. On Irregularitiesobserved in the directionof the Compass Needles of H. M. S. Isabella and Alexander, in their late Voyage of Discovery,and caused by the attractionof the iron containedin the Ships. By CaptainEdward Sabine, of the Royal Regiment of Artillery, F. R. S. &c.. 1 12 IX. Some observationson the formation of Mists in particular situations. By SirH. Davy, Bart. F. R. S. V. P. R . L p. 1i3 X. Observationson the Dip and Variationof the MagneticNeedle, and on the Intensityof the Magnetic Force; madeduring the late voyage in searchof a North West Passage. By Captain , of the Royal Regimentof Artillery, F. R. S. and F. L. S. 1 XI. On the action of crystallizedsurfaces upon light. By David Brewster, LL. J.. R. S. Lond. and Edin. In a letter addressedto theRight Hon. Sir Joseph Banks, Bart. G. C. B. P.R.S. p. 145 MeteorologicalJournal for 8188,kept at the Apartmentsof thei Royal Society. The PRESIDENTand COUNCILof the ROYALSOCIETY ad- judged the Medal on Sir GODFREY COPLEY'SDonation, for the year 1818, to ROBERT SEPPINGS, Esq. for his Papers on the Con- struction of Ships of War, printed in the Philosophical Transac- tions; and the Gold and Silver Medals on the Donation of BENJAMIN COUNT of RUMFORD, to DAVID BIEWSTEIB, LL.D. F. R.S. for his Discoveries relating to the Polarisation of Light. PHILOSOPHICAL

TRANSACTIONS,

OF THE

ROYAL SOCIETY

OF

LONDON.

FOR THE YEAR MDCCCXIX.

PART II.

LONDON,

PRINTED BY W, BULMER AND CO. CLEVELAND ROW, ST. JAMES'S;

AND SOLD BY G. AND W. NICOL, PALL-MALL, BOOKSELLERS TO IIIS MAJESTY, AND PRINTERS TO THE ROYAL SOCIETY.

MDCCCXIX. C NT E N TS.

XII. On the specfic gravity, and temperatureof Sea Waters, in differentparts of the Ocean,and in particularseas; with some accountof theirsaline contents. By Alexander Marcet, M.D. F. R. S. &c. p. :16 XIII. An account of the fossil skeletonof the Proteo-saurus. By Sir EVERARDHOME, Bart. V. P. R. S. p. 209 XIV. Reasonsfor giving the nameProteo-saurus to the fossil skeleton which has been described. By Sir EVERARD HOME, Bart. V.P.R.S. 212 XV. Some Observationson the peculiarityof the Tides between Fairleigh and the North Foreland; with an explanation of the supposedmeeting of the Tides near Dungeness. By James Anderson, Captainin the Royal Navy. Commnunicatedby the Right Hon. Sir Joseph Banks, Bart. G. C. B. P. R. S. p. 217 XVI. On the Ova of the differenttribes of Opossumand Orni- thorhynchus.By Sir Everard Home, Bart. V. P. R. S. p. 234 XVII. The resultsof Observationsmade at the Observatoryof Trinity College,Dublin, for determiningthe Obliquityof the Ecliptic,and the Maxinum of the Aberrationof Light. By the Rev. J. Brinkley, D. D. F.R. S. and M. R. L A. and An- drew's Professorof Astronomyin the Universityof Dublin. p. 241 XVIII. On some new Methodsof investigating the Sums of severalClasses of infiniteSeries. By Charles Babbage, Esq. A. M F. R. S2 Po 249 C vi

XIX. On the optical and physical propertiesof Tabasheer. By David Brewster, LL.D.D. R. S. Lond. and Edin. In a Letter to the Right Hon. Sir Joseph Banks, Bart. G. C. B. P. R. S. &c &. &C. p. 283 XX. An Accountof a Membranein the Eye, nowfirst described. By Arthur Jacob, M. D. Memberof the Royal College of Surgeons,Ireland; Demonstratorof Anatomy,and Lectureron the Diseases of the Eye in the Universityof Dublin. Commu- nicatedby James Macartney, M. D. F. R. S. p. Soo XXI. A new methodof solving numericalequations of all orders, by continuousapproximation. By W. G. Horner, Esq. Com- municatedby Davies Gilbert, Esq. F. R. S. p. 3o8 PHILOSOPHICAL

T RAN SAC T I ON S,

OQFTHE ROYAL SOCIETY

OF

LONDON.

FOR THE YEAR MDCCCXIX.

PART III.

LONDON,

PRINTED BY W. BULMER AND CO. CLEVELAND BOW, ST. JAMES'S;

AND SOLD BY G. AND W. NICOL, PALL-MALL, BOOKSELLERS TO HIS MAJESTY, AND PRINTERS TO THE ROYAL SOCIETY,

MDCCCXIX. CO N T E NT S.

XXII. An accountof experimentsfor determiningthe variation in the length of the pendulumvibrating seconds, at theprinci- pal stations of the TrigonometricalSurvey of Great Britain. By Capt. HENRY KATER, F. R. S. - p. 337 List of Presents, p. 509 Index.