Royal Astronomical Society. 557 



was translated into German ; it is not improbable that some here 

 present may have learned their first ideas of that science from it. 

 His edition of Dr. Hutton's Course of Mathematics was considerably 

 augmented by himself, and is the best of them all. As an accurate 

 observer, he is known by his experiments on the velocity of sound, 

 which agree almost exactly with those of the first French and three 

 Dutch observers, who were almost simultaneously employed on the 

 same subject*. 



" We have frequently to record losses which bear more directly 

 on practical astronomy, but it is not often that we have to regret the 

 termination of a more energetically useful career, and never of a 

 more zealous one. The principal works known to have been written 

 or edited by him are as follow : — 

 1793. Lessons, Astronomical and Philosophical, 1 vol. 



1801. Treatise on Astronomy, 1 vol. 



1802. The Gentleman's Diary, under his editorship. 



1806. Treatise on Mechanics, 3 vols. 



1807. Translation of Hauy's Natural Philosophy, 2 vols. 



1808. Pantalogia, of which he was the general editor, and the con- 



tributor of about one half, 12 vols. 

 1810. Third volume of Dr. Hutton's Course of Mathematics, of 

 which he wrote about one half; and he afterwards edited 

 an edition of the whole course. 



Letters on the Evidences, &c. of Christianity, 2 vols. 



1815. Tracts on the Trigonometrical Survey. 



1816. Plain and Spherical Trigonometry, 1 vol. 



Dissertation on Weights and Measures. 



1817. An account of his Pendulum Experiments and Astronomical 



Observations made at Shetland, in the Philosophical Ma- 

 gazine [First Series, vol. liii. p. 426.]. 



1818. Appointed editor of the Ladies' Diary and general super- 



intendent of the Stationers' Company's Almanacs. 

 1825. Mathematics for practical Men, 1 vol. 



1839. Address to the Cadets of the Royal Military Academy on 



resigning the Professor's Chair. 



1840. Hints to Mathematical Teachers, 1 vol. 



— — Tables to be used with the Nautical Almanac. 



" He was also, at one period of his life, a large contributor to the 

 leading reviews. 



" Thomas Leybourn, Esq. Fellow of the Royal Society, late senior 

 Professor of Mathematics in the Royal Military College, was one 

 of the original members of this Society, having been admitted by 

 the founders in 1820. Mr. Leybourn was born in 1769, at Bishop- 

 Middleham, in the county of Durham. Although he had not the 

 advantages of a regular education, he appears to have devoted him- 

 self to mathematical studies from an early period of life ; for, soon 

 after 1790, he was a correspondent of Dr. Hutton in the Ladies' 

 Diary; and, in 1795, he became known to the public as the editor 



[* Dr. Gregory's paper on this subject will be found in Phil. Mag., 

 vol. lxiii. p. 401.— Ed.]. 



