318 George Carey Foster. 



By senior and painstaking students he was much appre- 

 ciated ; and, though he made no claim to encyclopaedic 

 knowledge, his acquaintance with German treatises enabled 

 him to direct enquirers to original sources, and to stimulate 

 a certain type o£ research ; while his natural bent led him 

 to encourage exact measurement. He gave constant and 

 conscientious attendance in the physical laboratory where 

 the students worked ; indeed in early days he allowed the 

 more advanced ones to work in what should have been 

 his private room, which he had fitted up with benches and 

 glass cases, since no other place was available ; and here he 

 practically initiated a students' physical laboratory which, 

 must have been a pioneer institution in this Country — at 

 any rate south of the Tweed. 



He was very modest about his own work, and sometimes 

 seemed rather surprised at the importance attached by 

 physicists to his Paper before what was then the Society of 

 Telegraph Engineers (now the Institution of Electrical 

 Engineers) on the Wheatstone Bridge. But, at the time 

 it was written, it was a most ingenious and instructive piece 

 of work, and displayed a number of special features which 

 anyone less critically thorough than himself would have 

 overlooked. Undoubtedly he therein devised the method — 

 not at all an obvious method — tor extremely uccnrate 

 comparison of standards of resistance, turning the bridge 

 into an instrument for the measurement of differences instead 

 as previously only of ratios, and thus importantly supple- 

 menting Wheatstone's or Christie's original design. 



The principle of the Carey Foster Bridge was also used 

 by him for a very accurate and convenient method of 

 plotting the equipotential lines of a current flowing 

 between electrodes situated anywhere in a plane conducting 

 sheet. [See Phil. Mag. December 1875, a sequel to papers 

 in May and June of the same year. A further paper in the 



