ROY, WILLIAM, Maj.gen. in the British army, was horn May 4, 1700, at Milton Head, in the parish of Carlake, Lanarkshire. His early history is quite unknown, and the incidents of his professional career comparatively unimportant, but his name will always be remembered by succeeding generations as that of the first of British geodesists. After the great rebellion in 1745. be was employed its preparing for government a map of the Highlands, and finally of the whole mainland, which, however, owing to imper fect instruments, and the hurried nature of the survey, was only, to use Roy's own words, " a magnificent military sketch." Roy's next important operation was the meas uring a base line (see ORDNANCE SURVEY) on Hounslow Heath, of 27,404t ft., or about Gila., which, though the first measurement of the kind in Britain which pretended to accuracy, was executed with such care, that, on being remeasured after Roy's death, the difference between the two results was found to be only 21- inches. For this splen did labor, Roy received time royal society's Copley medal. Roy's labors connected with
the survey extended from July, 1787, till Sept., 1783. when he returned to London in ill health, which necessitated his removal to the warmer latitude of Lisbon in the winter of 1739; but he returned to London in the following April, and died there July 1, 1700. In 1707 Roy was elected a fellow of the Royal society, to whose Transactions he con tributed, in 1777, a paper entitled "Experiments and Observations mhde in Britain, in order to obtain a Rule for Measuring Heights with the Barometer." He had also, during his survey of Scotland, paid particular attention to the camps and other Roman remains in that country, and had completed an elaborate work on this subject, illustrated by drawings and plans, and by a copy of his map of the country. This work was pub lished (1703) by the society of antiquaries (of which Roy had been a member), to whom it had been presented by Roy's executors. Roy was also surveyor-general of the coasts of Great Britain.