LESLIE. 77 



error, he has led the way to the still more delicate researches which 

 have followed. 



Captain Kater also instituted a series of experiments as to the 

 best kind of steel and shape for compass needles ; it resulted in the 

 adoption of the shear clock-spring steel, and the pierced rhombus 

 form, in the proportion of five inches in length to two in width. In 

 the year 1831 he received the gold medal of the Royal Astronomical 

 Society, for the construction of his floating collimator, an instru- 

 ment for ascertaining the accurate zero or level points of divided 

 astronomical instruments. The optical principle upon which it 

 depends is a very beautiful one, and the invention of Kater, with 

 several improvements in point of form, has become the auxiliary of 

 nearly every observatory in the world, being one of those small but 

 happy improvements which affect materially the progress of science. 

 Most of the learned societies in Great Britain and on the Continent 

 testified at different times their sense of the value of his services, 

 by enrolling him among their members. The Emperor of Russia 

 employed him to construct standards for the weights and measures 

 of his dominions, and was so pleased with the execution of them, 

 that he presented Kater with the Order of St. Anne and a diamond 

 snuff-box. The greater part of his publications appeared in the 

 1 Philosophical Transactions ' of the Royal Society, chiefly between 

 the years 1813 and 1828. 



Captain Kater died from a severe affection of the lungs, at his 

 residence, York Gate, in the fifty-third year of his age. Athenaeum, 

 May, 1835. Weld's History of the Royal Society. London, 1848. 

 Monthly Notices of the Royal Astronomical Society, vol. 3, February, 

 1836. Sixth Dissertation Encyclopaedia Britannica, Eighth Edition. 



SIR JOHN LESLIE, F.R.S.E., &c. 



Bora April 16, 1766. Died November 3, 1832. 



Sir John Leslie, Professor of Natural Philosophy in the University 

 of Edinburgh, the son of a poor joiner or cabinetmaker, was born at 

 the village of Largo, in the county of Fife. Although both weak 

 and sickly as a child, he soon acquired considerable knowledge of 

 mathematical and physical science, and at the age of eleven at- 

 tracted the notice of Mr. Oliphant, the minister of the parish, by his 

 precocious attainments. This gentleman kindly lent young Leslie 

 some scientific books, and strongly advised him to continue the 

 study of Latin, for which he had a great aversion, although in after 

 life he attained considerable proficiency hi that language. 



