XI. APPLICATIONS. 329 



10. Abel's electric detonator (land service) and section. No. 5. 



11. Abel's electric detonator (submarine) and section. No. 7. 



12. Naval electric gun tube and section. 



13. Low tension detonator and section. No. 9. 



. Glass case and printed labels. War Office. 



1728a. Electrical Communicator. Garnham $ Co. 



This invention enables a perfect communication to be maintained between 

 guards and drivers, and passengers and guards, by means of electricity. The 

 want of a thorough system of communication between guards and drivers on 

 long trains has long been felt, as it is well known that the guard in the after 

 part of a train cannot at all times hear the driver's whistle. By means of this 

 electrical communication a perfect code of signals can be maintained. In the 

 case of danger passengers can readily give an alarm to the guard, and this 

 passenger signal continues ringing until the guard replaces it, and it therefore 

 indicates the compartment of a train in which the alarm bell was sounded. 

 The apparatus consists of a simple battery with the necessary communicators ; 

 it is simple, inexpensive, and not liable to get out of order, and is also readily 

 applied to all existing trains. 



1729. Glass Globes for producing Electricity by rubbing 

 with the hand. 



Museum of King George III., King's College, London. 



The globes are caused to revolve by means of multiplying wheels and a 

 band of rope. The globes may be exhausted when they become luminous ; 

 the greatest amount of electricity or " fire " was obtained from them when 

 they were exhausted. In the one with a large brass cap, a small wooden disc 

 could be inserted with threads distributed round its edge ; when the globe 

 was excited the threads stood out from the edge of the disc. Constructed 

 about A.D. 1720. 



c. ELECTRO-CHEMICAL APPLICATIONS. 



1730. Illustration of the Electrotype Process to the 

 Reproduction of Works of Art. 



Messrs. Elkington and Co. 



Reproduction of a medal. This is an object composed of two parts only, 

 viz., the obverse and the reverse. 



a and 6. Moulds in gutta percha, &c. of the obverse and the reverse. 



c and d. Moulds with the copper deposited in them. 



e and/. Copper deposits removed from the moulds. 



g. The two sides or portions of the medal as deposited, soldered together 



ready for finishing. 



h. Electro-deposited copy or reproduction of the medal, gilt or silvered. 

 Reproduction of a small candlestick : 



a. The moulds of the base and two sides of the nozzle in gutta percha, 



&c. 



b. Moulds with the copper deposited in them. 



