OP THE LATE MB. WILLIAM STUBGEON. 67 



papers published almost simultaneously in the beginning of 

 1835. In 1837 Mr. Sturgeon produced his electro -magnetic 

 coil machine, consisting of a coil of thick wire surrounded by 

 a helix of thin wire. The coil of thick wire was in connection 

 with a pair of galvanic plates : an arrangement being made 

 for rapidly making and breaking the circuit. The ends of 

 the helix of thin wire were employed to communicate the 

 shock, which is further enhanced by the insertion into the 

 axis of the coil of a bundle of iron wires, or a scroll of thin 

 sheet iron. This apparatus is the most efficient ever em- 

 ployed by medical practitioners, and its power is such that 

 "a strong shock and bright spark are produced when the 

 battery employed consists of a copper and zinc wire (No. 1 5) 

 immersed one-tenth of an inch deep in dilute nitrous acid." 

 Mr. Dancer has made a capital improvement on this instru- 

 ment, by supplying a self-acting apparatus, consisting of a 

 piece of iron attached to a spring, by the intermittent attrac- 

 tion of which the use of a toothed wheel is dispensed with. 



A research concerning the fracture of leyden jars by elec- 

 trical explosions conducted Mr. Sturgeon to the discovery of 

 the means of preventing such accidents, by connecting the 

 inner coating of the jar with the rod which supports the ball 

 by means of strips of tinfoil. So effectual did Mr. Sturgeon 

 find this simple contrivance to be, that during twelve years 

 he did not break a single jar, although during that period he 

 discharged a battery of twelve jars some hundreds of times 

 from the most intense electrization. 



In the autumn of 1838, a series of experiments was per- 

 formed at the house of Mr. Gassiott, of Clapham-common, 

 with a voltaic battery which was the joint property of Mr. 

 Gassiott and Mr. Mason. These experiments appear to have 

 been conducted by Messrs. Gassiott, Mason, Sturgeon, and 

 Walker. After various interesting results had been ob- 

 tained, Mr. Sturgeon, who had been previously requested to 

 provide a catalogue of the experiments which it would be 



