Front Matter

ADVERTISEMENT. The Committee appointed by the Royal Society to direct the publication of the Philosophical Transactions, 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 declarations 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 recommending 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 them such as they should judge most proper for publication in the future Transactions; which was accordingly done upon the 26th of March 1752. And the grounds of their choice are, and will continue to be, the importance and singularity of the subjects, or the advantageous 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 subject, 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 receive 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 curiosities 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 newspapers, 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 dishonour of the Society. CONTENTS OF VOL. LXXXI. PART I. I. A SECOND Paper on Hygrometry. By J. A. De Luc, Esq. F. R. S. Page 1 II. On the Production of Ambergris. A Communication from the Committee of Council appointed for the Consideration of all Matters relating to Trade and Foreign Plantations; with a prefatory Letter from William Fawkener, Esq. to Sir Joseph Banks, Bart. P. R. S. p. 43 III. Observations on the Affinity between Basaltes and Granite. By Thomas Beddoes, M. D.; communicated by Sir Joseph Banks, Bart. P. R. S. p. 48 IV. On Nebulous Stars, properly so called. By William Herschel, LL.D. F. R. S. p. 71 V. Abstract of a Register of the Barometer, Thermometer, and Rain, at Lyndon in Rutland; by Thomas Barker, Esq.; with the Rain in Hampshire and Surrey; for the Year 1789. Communicated by Thomas White, Esq. F. R. S. p. 89 VI. Observations on certain horny Excrescences of the Human Body. By Everard Home, Esq. F. R. S. p. 95 VII. Con- VII. Considerations on the Convenience of measuring an Arch of the Meridian, and of the Parallel of Longitude, having the Observatory of Geneva for their common Intersection. By Mark Augustus Pictet, Professor of Philosophy in the Academy of Geneva; in a Letter to Sir Joseph Banks, Bart. P. R. S. APPENDIX. Meteorological Journal kept at the Apartments of the Royal Society, by Order of the President and Council. CONTENTS OF VOL. LXXXI. PART II. VIII. On the Rate of Travelling, as performed by Camels; and its Application, as a Scale, to the Purposes of Geography. By James Rennell, Esq. F. R. S. Page 129 IX. On Infinite Series. By Edward Waring, M. D. F. R. S. Lucasian Professor of Mathematics in the University of Cambridge. p. 146 X. An Account of some Appearances attending the Conversion of cast into malleable Iron. In a Letter from Thomas Beddoes, M. D. to Sir Joseph Banks, Bart. P. R. S. p. 173 XI. On the Decomposition of Fixed Air. By Smithson Tennant, Esq. F. R. S. p. 182 XII. A Meteorological Journal, principally relating to Atmospheric Electricity; kept at Knightsbridge, from the 9th of May, 1789, to the 8th of May, 1790. By Mr. John Read; communicated by R. H. A. Bennet, Esq. F. R. S. p. 185 XIII. Farther Experiments relating to the Decomposition of dephlogisticated and inflammable Air. By Joseph Priestley, LL.D. F. R. S. p. 213 XIV. Expe- XIV. Experiments on Human Calculi. In a Letter from Mr. Timothy Lane, F. R. S. to William Pitcairn, M. D. F. R. S. p. 223 XV. Chermes Lacca. By William Roxburgh, M. D. of Samulcotta. Communicated by Patrick Russell, M. D. F. R. S. p. 229 XVI. The Longitudes of Dunkirk and Paris from Greenwich, deduced from the Triangular Measurement in 1787, 1788, supposing the Earth to be an Ellipsoid. By Mr. Isaac Dalby; communicated by Charles Blagden, M. D. Sec. R. S. p. 236 XVII. On the Method of determining, from the real Probabilities of Life, the Values of contingent Reversions in which Three Lives are involved in the Survivorship. By Mr. William Morgan, F. R. S. p. 246 XVIII. Abstract of a Register of the Barometer, Thermometer, and Rain, at Lyndon in Rutland; by Thomas Barker, Esq.; with the Rain in Hampshire and Surrey; for the Year 1790. Communicated by Thomas White, Esq. F. R. S. p. 278 XIX. Description of a simple Micrometer for measuring small Angles with the Telescope. By Mr. Tiberius Cavallo, F. R. S. p. 283 XXI. Experiments and Observations to investigate the Composition of James's Powder. By George Pearson, M. D. F. R. S.; communicated by Sir Joseph Banks, Bart. P. R. S. p. 317 XXII. An Account of some chemical Experiments on Tabasheer. By James Louis Macie, Esq. F. R. S. p. 368 XXIII. A Second Paper on Hygrometry. By J. A. De Luc, Esq. F. R. S. p. 389