of 1 April 1764, showing its time and phases at Greenwich (Phil. Trans. liii. 240). He observed the event at Liverpool (ib. liv. 108). In 1767 he revisited Scotland, and at Edinburgh associated intimately with William Buchan [q. v.], author of ‘Domestic Medicine,’ and Dr. Lind, the electrician. He soon afterwards introduced a lecture on electricity into his course. One of his most popular works, ‘The Young Gentleman's and Lady's Astronomy, familiarly explained in Ten Dialogues between Neander and Eudosia,’ was published in 1768. It is written with such clearness that, as Madame de Genlis remarked, ‘a child of ten years old may understand it perfectly from one end to the other.’ The interlocutors represent Ferguson himself and his gifted pupil Anne Emblin, afterwards the wife of Mr. Capel Lofft, who hence entitled his poem on the universe (1781) ‘Eudosia.’
From 1768 George III often invited Ferguson to interviews with him to discuss mechanics. Early in 1769 he reprinted a paper communicated six years earlier to the Royal Society under the title ‘A Delineation of the Transit of Venus expected in the Year 1769’ (ib. liii. 30). His lectures at Newcastle-on-Tyne in 1770 were patronised by Dr. Hutton, who was surprised to learn from him that he was not only ignorant of geometry, but incapable of apprehending a geometrical demonstration (Hutton, Tracts, iii. 379). Conviction of the truth of a proposition was attainable by him only through measurement of the construction for proving it. On the conclusion of his course at Derby in the autumn of 1772, he visited the Peak district, and read before the Royal Society on 16 Nov. an account of the Devil's Cave, subsequently published as a tract. His scattered papers were collected in 1773 into a volume entitled ‘Select Mechanical Exercises’ (4th ed. 1823), the partial autobiography prefixed to which is the chief source of information regarding his early life. He was interrupted in its composition by the death of his wife, of consumption, on 3 Sept. 1773, at the age of 52. His domestic affairs were thenceforward cared for by his sister Janet, who had come to London to attend on Mrs. Ferguson. His own health, never robust, soon after began to decline; yet he lectured in London, Bath, and Bristol in 1774, and wrote, in 1775, ‘The Art of Drawing in Perspective made easy to those who have no previous knowledge of the Mathematics,’ of which five editions appeared previous to Brewster's in 1823. He died at 4 Bolt Court, Fleet Street, on 16 Nov. 1776, aged 66, and was buried in the churchyard of St. Marylebone. His intellect remained unclouded, and his lips moved in prayer to the last.
In spite of his apparent poverty he died worth about 6,000l. The plea of a recent legacy from a distant relative (Gent. Mag. 1777, p. 108) has little to support it. Dr. Houlston of Liverpool, who knew him intimately, testifies to his amiability, simplicity, and absence of pedantry (Ann. Register, xix. 53). He adds that he was ‘unhappy in his family connections.’ ‘Somewhere about the year 1770,’ it is elsewhere related, ‘while Ferguson was delivering a lecture on astronomy to a London audience, his wife entered and maliciously overturned several pieces of his apparatus. Ferguson, observing the catastrophe, only remarked the event by saying, “Ladies and gentlemen, I have the misfortune to be married to this woman”’ (The Mirror, 25 Nov. 1837).
His only daughter, Agnes, described as elegant, vivacious, and learned, suddenly deserted her father in 1763, when in her eighteenth year, and was never again heard of by him. The doctor who attended her in her last illness left the miserable story of her life scribbled on the fly-leaf of a tract in the British Museum. After a disreputable career she died of consumption in a garret near Charing Cross, 27 Jan. 1792.
Ferguson's eldest son, James, a young man of some promise, died, likewise of consumption, on 20 Nov. 1772, at the age of twenty-four. Two younger sons were trained as surgeons at Aberdeen, but one never practised, and the other failed in his profession; neither left issue.
Four original portraits of Ferguson are extant; the best, a mezzotint by Townsend, an engraving from which by Stewart was published in December 1776, and was prefixed in 1778 to the second edition of his ‘Select Mechanical Exercises.’ It corresponds well with Andrew Reid's description of his aspect about 1774. ‘Mr. Ferguson had a very sedate appearance, face and brow a little wrinkled; he wore a large full stuff wig, which gave him a venerable look, and made him to appear older than he really was’ (Henderson, Life of Ferguson, p. 463).
Ferguson's great merit as a scientific teacher lay in clearness, both of thought and style, and in the extreme ingenuity with which by means of machines and diagrams he brought the eye to help the mind of the learner. Hutton recognised his ‘very uncommon genius, especially in mechanical contrivances and executions.’ Brewster considered him as ‘in some degree the first elementary writer on natural philosophy’ (Preface to Ferguson's Essays, 1823).
