76 KATER. 



hitherto exclusive devotion to abstract science. Mr. Kater con- 

 tinued for two years to remain in a pleader's office, during which 

 time he acquired a considerable portion of legal knowledge, on 

 which he valued himself through life ; but the death of his father, 

 in 1794, permitted him to resume his favourite studies ; and bidding 

 adieu to the law, he obtained a commission in^the 12th Regiment of 

 Foot, at that time stationed in India. 



During the following year, Mr. Kater was engaged in the trigo- 

 nometrical survey of India under Colonel Lambton, contributing 

 greatly, by his untiring labours, to the success of that vast under- 

 taking. About the same period, he was also occupied in construct- 

 ing a peculiarly sensible hygrometer, of which he published a 

 description in the ' Asiatic Researches.' Mr. Kater remained in 

 India seven years, during which time his unremitting study in a 

 hot climate greatly injured his constitution, and was the cause of 

 his falling into a state of ill health, from which he suffered more or 

 less until the end of his life. 



On his return to England, he qualified himself to serve on the 

 general staff, and later in life retired on half-pay, from which period 

 he devoted himself entirely to science. When Parliament, in the 

 years 1818-19, determined on establishing an uniform system of 

 weights and measures, Captain Kater, in conjunction with Sir 

 Joseph Banks, Sir George Clerk, Davies Gilbert, and Drs. Wollaston 

 and Young, was appointed to investigate this most important sub- 

 ject; and he instituted a series of experiments with a pendulum 

 made of a bar of brass, 1 inches wide and | of an inch thick, to 

 which two knife-edges of a kind of steel prepared in India, and 

 known by the name of wootz, were attached, playing upon agate 

 plates. The knife-edges were placed in a parallel direction on the 

 brass bar, facing opposite ways upon either of which it might be 

 swung. They were so arranged, that when either was used as the 

 point of suspension the other nearly represented the centre of oscil- 

 lation, and by means of a small adjustable weight, this condition 

 might be accurately fulfilled. These experiments were made in the 

 house of Mr. H. Browne, F.R.S., which was situated in a part of 

 Portland Place not likely to be disturbed by carriages. They occu- 

 pied Captain Kater's close attention for several years ; and he has 

 permanently attached his name to the beautiful theorem of Huygens 

 respecting the reciprocity of the centres of oscillation and suspen- 

 sion, and their consequent quality of convertibility. Although this 

 was a property already known to belong to the centre of oscillation, 

 it had never hitherto been practically applied to determine the 

 exact length of a pendulum vibrating seconds; it was, therefore, 

 highly creditable to his ingenuity, and claims the same order of 

 merit as an original invention. In this, as well as in Kater's 

 laborious inquiries respecting a standard of weights and measures, 

 even where his conclusions have not escaped all the chances of 



