Mr. Ivory attained the age of seventy-seven before his death; he was essentially a self-taught mathematician, and spent most of his leisure in retirement. He fathomed in private the profoundest writings of the most learned continental mathematicians, and at a period when few Englishmen were able to understand those difficult works; he even added to their value by many original contributions, and must always be remembered with special interest when the singular destitution of higher mathematical talent, which had reigned in this country for so long a period before his time, is considered.--_English Cyclopædia._ London, 1856.--_Encyclopædia Britannica._ Eighth Edition. JOSEPH PRIESTLY, LL.D. Born March 24, 1773. Died February 26, 1804. Joseph Priestly was the son of a cloth-dresser at Burstal-Fieldhead, near Leeds. His family appear to have been in humble circumstances, and he was taken off their hands after the death of his mother by his paternal aunt, who sent him to a free school at Batley. There he learnt something of Greek, Latin, and a little Hebrew. To this he added some knowledge of other Eastern languages connected with Biblical literature; he made a considerable progress in Syriac and Chaldean, and began to learn Arabic; he also had a little instruction in mathematics, but in this science he did not make much proficiency. Indeed his whole education was exceedingly imperfect, and, excepting in Hebrew and Greek, he never afterwards improved it by any systematic course of study. Even in chemistry, the science which he best knew, and in which he made so important a figure, he was only half-taught, so that he presents one of the memorable examples of knowledge pursued, science cultivated, and even its bounds extended, by those whose circumstances made their exertions a continued struggle against difficulties which only genius like theirs could have overcome. After studying for some years at the Dissenting Academy founded by Mr. Coward at Daventry (afterwards transferred to London), Priestly quitted Daventry and became minister of a congregation at Needham Market, in Suffolk, where his salary never exceeded thirty pounds. He had been brought up in the strictest Calvinistic principles, but he very soon abandoned these, and his tenets continued in after life to be those of the moderate Unitarians, whose leading doctrine is the proper humanity of Christ, and who confine all adoration to one Supreme Being. Priestly's religious opinions proving distasteful to his congregation at Needham Market, caused him to remove in 1758 to Nantwich, in Cheshire, where he obtained a considerable number of pupils, which greatly increased his income and enabled him by strict frugality to purchase a scanty scientific apparatus, and commence a study of natural philosophy. In 1761, Priestly removed to Warrington, where he was chosen to succeed Dr. Aitken as tutor in the _belles lettres_ at that academy. On settling at Warrington he married the daughter of Mr.