MAJOR-GENERAL WILLIAM, a famous geodesist, was employed in some of the great national trigonometrical measurements which were made during last century. In 1746 and 1747, while colonel of artillery, he surveyed and mapped out the whole mainland of Scotland. In 1784 he measured a base on Hounslow Heath, designed to be the germ of all subsequent scientific surveys of the United Kingdom. His aid was also employed in 1787 and 1788 in ascertaining, by observations from the above-mentioned base, the relative positions of the French and English royal observatories. He had completed this undertaking, and was just finishing an account of it for the Philosophical Transactions when he died in 1790. Besides several papers on his own operations in the Philosophical Transactions, General Roy is the author of a book entitled The Military Antiquities of the Romans in North Britain, &c., London, 1793.