a sealed tube to the top of the mountain, where, filling it with quicksilver, and inverting it in a basin, he marked the elevation of the suspended column, and repeated the same experiment below; a very rude method, certainly,—but no better was practised in England for more than thirty years afterwards. To the instrument fitted up in a frame, Sinclair first gave the name baroscope, or indicator of weight; a term afterwards changed for barometer, or measurer of weight. In these rude attempts at measuring weights by the mercurial column, the atmosphere was regarded simply as an homogeneous fluid, and possessing the same density throughout its whole mass; a supposition, which, it is needless to point out, must hare led the observer wide of the truth, where the elevation was considerable.
The work by which Sinclair is now best remembered is his "Satan's Invisible Works Discovered," which was published about the year 1685, and has since been frequently reprinted. This is a treatise on witches, ghosts, and diablerie, full of instances ancient and modern, and altogether forming a curious record of the popular notions on those subjects at the period when it appeared: it was for a long time a constituent part of every cottage library in Scotland In Lee's Memorials for Bible Societies in Scotland, is given the following decree of the Privy Council, in favour of Mr Sinclair's copyright in this precious production: "Apud Edinburgh, 26 Feb., 1685. The lords of his majesties privy councill considered ane address made to them by Mr George Sinclair, late-professor of philosophic at the colledge of Glasgow, and author of the book entitled 'Satan's Invisible Works Discovered,' &c., doe hereby prohibite and discharge all persons whatsomever from printing, reprinting, or importing into the kingdome any copy or copies of the said book during the space of eleven zearis after the date hereof without licence of the author or his order, under the pain of confiscation thereof to the said author, besydes what further punishment we shall think fitt to inflict upon the contraveeners." The first edition contains a very curious dedication to the earl of Winton, not to be found in the rest, but which has been lately republished in the "Historic of the Hous and Name of Setoun," printed by the Maitland Club.
It is curious to find science and superstition so intimately mingled in the life of this extraordinary person. In 1688, he published at Edinburgh, in 12mo, the "Principles of Astronomy and Navigation." The only other publication attributed to him is a translation of David Dickson's "Truth's Victory over Error." It is hardly possible to censure delusions which seem to have been entertained with so much sincerity, and in company with such a zeal for the propagation of real knowledge.
Mr Sinclair was recalled at the Revolution to the charge from which he was expelled twenty-six years before. On the 3rd of March, 1691, the faculty of the college revived the professorship of mathematics, which had been suppressed for want of funds; and at the same time appointed Mr Sinclair to that chair. Me died in 1696.
SIMSON, (Dr) Robert, a mathematician, was the eldest son of Mr John Simson of Kirton-hall, in Ayrshire, and was born on the 14th October, 1687. He was educated at the university of Glasgow, which he first entered as a student in 1701. Being intended for the church, his studies were at first directed chiefly to theological learning, in which, as well as in the classics, he made great progress. He distinguished himself also by his historical know- ledge, and was accounted one of the best botanists of his years. At this time no mathematical lectures were given in the college; but, having amused himself in his leisure hours by a few exercises in Euclid, a copy of which he found in the hands of a companion, he quickly found that the bent of his taste and
