422 SIR JOHN LESLIE.
asserted, by the term ' conditional,' by which he means to restrict it, and he expects that we are to take his explanation without a murmur ; although, when Mr Leslie would confine the assertion in his note to * objects of physical exam- ination,' he obstinately fixes him down to his original expressions, and rejects the limitation as utterly inadmissible. Unfortunately, sir, the doctrine of the ministers of Edinburgh, with regard to such a necessary connexion between cause and effect as implies an operating principle in the cause, stands in its ori- ginal state in the protest which they gave to the town-council. It is recorded in the council books ; and there it must remain in all future times, without any explanation whatever, be its tendency or its heresy ever so mischievous.
" The use," he continued with exquisite sarcasm, " which may be made of incautious expressions, may be as forcibly illustrated from the protest of the ministers of Edinburgh, as from the note of Mr Leslie. But there is this ma- terial distinction between the two cases : Mr Leslie, at least, understood the precise meaning of his assertions, as far as they related to the subject of which he was writing ; but my reverend brethren enunciated their dogma in perfect innocence and simplicity, completely unconscious of its true import and ten- dency ! "
Near midnight, on the second day of the debate, it was determined by 96 against 84 to dismiss this vexatious case without further notice. On the vote being announced, a shout of applause an unwonted sound in the general as- sembly burst from the crowd assembled in the galleries.
Mr Leslie entered without further opposition upon the duties of his chair, and upon a course of experimental discovery by which he was to confer lustre upon the university. Through the assistance of one of his ingenious contrivances his hygrometer he arrived in 1810 at the discovery of that singularly beautiful process of artificial congelation, which enabled him to convert water and mer- cury into ice. " We happened," says a brother professor, " to witness the con- summation of the discovery at least, of the performance of one of the first suc- cessful repetitions of the process by which it was effected ; and we shall never forget the joy and elation which beamed on the face of the discoverer, as, with his characteristic good nature, he patiently explained the steps by which he had been led to it."
In 1809 Mr Leslie published his Elements of Geometry, which immediately became a class-book, and has since gone through four editions. He also pub- lished, in 1813, an " Account of Experiments and Instruments depending on the relation of Air to Heat and Moisture." In 1817 he produced his " Philo- sophy of Arithmetic, exhibiting a Progressive view of the Theory and Progress of Calculation," a small octavo; and, in 1821, his " Geometrical Analysis, and Geometry of Curve Lines, being volume second of a Course of Mathematics, and designed as an Introduction to the study of Natural Philosophy." 2 In 1822 he published " Elements of-Natural Philosophy," for the use of his class reprinted in 1829 and of which only one volume appeared. " Kudiments of Geome- try," a small octavo, published, 1828, and designed for popular use, was his last separate work. Besides these separate works, he wrote many admirable articles in the Edinburgh Review, three profound treatises in Nicholson's Philosophical Journal, a few in the Transactions of the Royal Society of Edinburgh, and several very valuable articles on different branches of physics in the Supple-
- The Elements of Geometry included Trigonometry and Geometrical Analysis in one
volume, for the three first editions ; and the curve lines of the second order was a small separ- ate work. In the fourth edition of the Geometry, 1820, one volume included Geometry and Trigonometry, and the second, published some time after, consisted of Geometrical Analjsis, including the curves of the second order, formerly published with the addition of the higher curves.