Front Matter

PHILOSOPHICAL TRANSACTIONS, OF THE ROYAL SOCIETY OF LONDON. VOL. LXXV. For the Year 178 PART I. LONDON, SOLD BY LOCKYER DAVIS, AND PETER ELMSLY, PRINTERS TO THE ROYAL SOCIETY. MDCCCLXXXV. 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. LXXV. PART I. I. An Account of an artificial Spring of Water. By Erasmus Darwin, M.D. F.R.S. page 1 II. An Account of an English Bird of the Genus Motacilla, supposed to be hitherto unnoticed by British Ornithologists; observed by the Rev. John Lightfoot, M.A. F.R.S. In a Letter to Sir Joseph Banks, Bart. P.R.S. p. 8 III. An Account of Morne Garou, a Mountain in the Island of St. Vincent, with a Description of the Volcano on its Summit. In a Letter from Mr. James Anderson, Surgeon, to Mr. Forsyth, His Majesty's Gardener at Kensington; communicated by the Right Honourable Sir George Yonge, Bart. F.R.S. p. 16 IV. A Supplement to the Third Part of the Paper on the Summation of infinite Series, in the Philosophical Transactions for the Year 1782. By the Rev. S. Vince, M. A.; communicated by Nevil Maskelyne, D. D. F. R. S. and Astronomer Royal. V. Description of a Plant yielding Asa foetida. In a Letter from John Hope, M. D. F. R. S. to Sir Joseph Banks, Bart. P. R. S. VI. Catalogue of Double Stars. By William Herschel, Esq. F. R. S. VII. Observations of a new Variable Star. In a Letter from Edward Pigott, Esq. to Sir H. C. Englefield, Bart. F. R. S. and A. S. VIII. Astronomical Observations. In two Letters from M. Francis de Zach, Professor of Mathematics, and Member of the Royal Academies of Sciences at Marseilles, Dijon, and Lyons, to Mr. Tiberius Cavallo, F. R. S. IX. Observations of a new Variable Star. By John Goodricke, Esq.; communicated by Sir H. C. Englefield, Bart. F. R. S. and A. S. X. On the Motion of Bodies affected by Friction. By the Rev. Samuel Vince, A. M. communicated by Anthony Shepherd, D. D. F. R. S. Plumian Professor of Astronomy and experimental Philosophy at Cambridge. XI. Observations and Experiments on the Light of Bodies in a State of Combustion. By the Rev. Mr. Morgan; communicated by the Rev. Richard Price, LL.D. F.R.S. XII. On the Construction of the Heavens. By William Herschel, Esq. F.R.S. XIII. Remarks on specific Gravities taken at different Degrees of Heat, and an easy Method of reducing them to a common Standard. By Richard Kirwan, Esq. F.R.S. p. 32 p. 36 p. 40 p. 127 p. 137 p. 153 p. 165 p. 190 p. 213 p. 267 XIV. Electrical Experiments made in order to ascertain the non-conducting Power of a perfect Vacuum, &c. By Mr. William Morgan; communicated by the Rev. Richard Price, LL.D. F.R.S. p. 272 XV. Experiments and Observations relating to Air and Water. By the Rev. Joseph Priestley, LL.D. F.R.S. p. 279 THE President and Council of the Royal Society adjudged, for the Year 1784, the Medal on Sir Godfrey Copley's Donation, to Edward Waring, M.D. Lucasian Professor of the Mathematics at Cambridge, for his Mathematical Communications to the Society. PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY OF LONDON. VOL. LXXV. For the Year 1785. PART II. LONDON, SOLD BY LOCKYER DAVIS, AND PETER ELMSLY, PRINTERS TO THE ROYAL SOCIETY. MDCCCLXXXV. CONTENTS OF VOL. LXXV. PART II. XVI. Of the Rotatory Motion of a Body of any Form whatever, revolving, without Restraint, about any Axis passing through its center of Gravity. By Mr. John Landen, F.R.S. page 311 XVII. Description of a new Marine Animal. In a Letter from Mr. Everard Home, Surgeon, to John Hunter, Esq. F.R.S. With a Postscript by Mr. Hunter, containing anatomical Remarks upon the same. p. 333 XVIII. A Description of a new System of Wires in the Focus of a Telescope, for observing the comparative Right Ascensions and Declinations of celestial Objects; together with a Method of investigating the same when observed by the Rhombus, though it happen not to be truly in an equatorial Position. By the Rev. Francis Wollaston, LL.B. F.R.S. p. 346 XIX. An Account of a Stag's Head and Horns, found at Alport, in the Parish of Youlgreave, in the County of Derby. In a Letter Contents. Letter from the Rev. Robert Barker, B.D. to John Jebb, M.D. F.R.S. p. 353 XX. An Account of the sensitive Quality of the Tree Averrhoa Carambola. In a Letter from Robert Bruce, M.D. to Sir Joseph Banks, Bart. P.R.S. p. 356 XXI. An Account of some Experiments on the Loss of Weight in Bodies on being melted or heated. In a Letter from George Fordyce, M.D. F.R.S. to Sir Joseph Banks, Bart. P.R.S. p. 361 XXII. Sketches and Descriptions of three simple Instruments for drawing Architecture and Machinery in Perspective. By Mr. James Peacock; communicated by Robert Mylne, Esq. F.R.S. p. 366 XXIII. Experiments on Air. By Henry Cavendish, Esq. F.R.S. and A.S. p. 372 XXIV. An Account of the Measurement of a Base on Hounslow-Heath. By Major-General William Roy, F.R.S. and A.S. p. 385 XXV. Abstract of a Register of the Barometer, Thermometer, and Rain, at Lyndon, in Rutland, 1784. By Thomas Barker, Esq. Also of the Rain at South Lambeth, Surrey; and at Seibourn and Fyfield, Hampshire. Communicated by Thomas White, Esq. F.R.S. p. 481