GREGORY, OLINTHUS GILBERT, was born at Yaxley, a small village in lInntingdolu3bire, January 29th 1774, of humble but respectable parents. At an early age he was placed under the care of the celebrated mathematician, Mr. Richard Weston, who was a contributor to the 'Ladies Diary,' and other mathematical publica tions of his day. Under his superintendence Mr. Gregory made much progress in his studies, for at the early ago of nineteen, and not long after leaving school, he published his ' Lessons, Astronomical and Philosophical.' Shortly afterwards he prepared an excellent treatise on the 'Use of the Sliding Rule,' which he submitted to Dr. Hutton, Professor of Mathematics, at the Royal Military Academy, Woolwich. This treatlee however was never published, though it con tained many valuable and original applications of the instrument, useful for practical purposes. This work was the means of opening a corre spondence between Mr. Gregory and Dr. Hutton, which ripened into mutual friendship, and was terminated only by death. In 1798, Mr. Gregory removed to Cambridge to assist the editor of a provincial news paper: he soon however relinquished the sub-editorship, and resolved to open a bookseller's shop, at the same time announcing his intention to give iostrnetion in the mathematical sciences, and resolving to follow that profession alone which should prove the more lucrative. The encouragement he met with as a preceptor speedily induced him to dispose of his books, and to devote his whole attention to the occupation of a mathematical instructor. His correspondence with the Ladies' Diary' commenced whilst he resided at Yaxley, In the year 1794, and he continued to write for that useful periodical during his stay at Cambridge. In 1800 he published his Treatiso on Astronomy,' which he dedicated to his friend and patron Dr. Hutton. This work brought him into much notice, and in the year 1302, the Stationers' Company appointed him editor of the ' Gentleman's Diary,' and another of their annual publications. About the same period be was appointed editor of the Pantalogia: and soon after, through the influence of Dr. Hnttoo, he was a mathematical master in the Royal Military Academy. In this situation he rose through the various gradations of office, and on the resignation of Dr. Hutton be filled the professor's chair with the highest reputation, until obliged,through indisposition brought on by intense application to study, to resign it in June 1833. The following is a list of hie published works :-1793, 'Lessons, Astronomical and l'hilosophical, 1 voL ; 1801, Treatise on Astronomy,' 1 vol.; 1802, appointed editor of the Gentleman's Diary ; 1806, Treatise on Mechanics,' 3 vols.; 1807, Translation of Haiiy's 'Natural Philosophy,' 2 vole.; 1803, Pante 'ogle,' of which he was the general editor, and the contributor of about one-half, 12 vols.; 1810, Third volume of Dr. Hutton'a 'Course of Mathematics,' of which he composed about one-half ; he afterwards edited an edition of the whole three volumes of the Course ; also Letters on the Evidence of Christianity,' 2 vole.; 1815, Tracts on
the Trigonometrical Survey ;' 1816, 'Plane and Spherical Trigono metry,' 1 vol.; also Dissertation on Weights and Measures ; ' 1817, Account of his 'Pendulum Experiments and Astronomical Observa tions made at Shetland this appeared in the Philosophical Maga zine;' 1818, appointed editor of the Ladies Diary,' and general superintendent of the Stationers' Company's Almanacs ; 1825, Mathe matics for Practical Men,' 1 vol.; 1839, 'Address to the Gentlemen Cadets of the Royal Military Academy,' on resigning the chair of Mathematics ; 1840, 'Hints to Mathematical Teachers, 1 voL ; and Tables to be used with the Nautical Almanac.' Soon after the publication of his excellent treatise on Mechanics, the University of Aberdeen conferred on him the title of LL.D., but the work by which Dr. Gregory is best known is his 'Evidences of Christianity; which has had an extensive sale, and has been reprinted in Bohn's Standard Library. He also wrote a 'Memoir of the Rev. Robert Hall,' which was originally published in the collected edition of Hall's Works, but was in 1813 republished, with additions as a distinct work, and again with Hall's Mi,cellaneous Works ' in Bohn'e Library. A memoir of Dr. Mason Good, and various easaye, also appeared from Dr. Gregory's pen. Dr. Gregory was a member of almost all the learned societies in Great Britain and the Continent, and was one of the twelve gentlemen who founded the Royal Astronomical Society, of which he was for some time the secretary. His connection with the Ladies' and Gentlemen's Diaries brought him into communi cation with young students who were desirous of distinguishing themselves in the exact sciences, and the period of his superintcndeuce of those valuable works will be long remembered as that in which every meritorious contributor found a friend in the editor.
In 1823 Dr. Gregory was employed at Woolwich in making experi ments to determine the velocity of sound. For this purpose he caused mortars, gun!, and muskets to be fired at various distances from the observer ; and his conclusion was that the velocity of sound, when not affected by the wind, is 1100 feet per second, when the temperature of the air is expressed by 33° (Fakir.); a result which agrees nearly with the result of experiments made at tho same time on the Continent.
Dr. Gregory's pleasing manners were completely in accordance with what might have been expected from the preceding remarks; all he did and said was dictated by benevolence of feeling, and he was a man of unbounded charity. As a Christian, he was moral and devout, and as a scholar he merited and obtained the of the first mathematicians of the day ; his great zeal in his vocatiou, his parental kindness, his earnest and impressive his enter taining, improving, and philosophical conversation, and his ever readiness to assist, will be gratefully remembered by many. He took a -warm interest in the cultivation of mathematics, to which he may be said to have devoted, with indefatigable perseverance, nearly the whole of his valuable life. He died February 2, 1841.