XI. APPLICATIONS. 377 



benzoliu lamp with sponge ; when once filled it is put in its place. By pressing 

 on the central button the lamp is made by the mechanism of the apparatus to 

 approach the platinum lighter (inflamateur), which is in the centre. On letting 

 the button go, the lamp is lighted. The cover of the lamp should be replaced 

 by the hand in order to prevent evaporation. 

 The box contains eight spare platinum plates. 



1709b. Detector of Disorder in Pneumatic Telegraph 

 Tubes. M. Bontemps, Telegraph Inspector, Paris. 



a. With bell. 



b. With differential manometer. 



17O3. Magnetic Ship Signal. Gcminiano Zanni. 



The above signal is composed of two parts, the sender and the receiver. 

 For actuating the sender, merely turn the handle over to the order required 

 to be sent, the dial of the receiver will indicate this order, and also repeat it 

 back to the sender. 



The magnetic current is caused by the motion of turning the handle or 

 crank to the order ; the use of the voltaic battery is dispensed witb. 



17O9c. Elisha Gray's Telephone, an instrument for trans- 

 mitting musical notes by means of electricity. 



Warden, Mmrhead, and Clark. 



A. Board for transmitting the four notes of the common chord, and two 

 receiving instruments, B, C. 



A reed vibrating the note to be transmitted is caused to interrupt the cur- 

 rent entering the line. At each vibration the interrupted current reproduces 

 the note at the distant* station by there setting a similar reed in vibration as 

 in the electro-magnetic receiver B, or by the friction of the finger (through 

 which the current is made to pass) on the zinc face of the revolving sounding 

 board. By means of the telephone several messages may be sent along a wire 

 at once, a different note being employed for each. 



APPLICATION TO NAVAL AND MILITARY PURPOSES. 



1711a. Military Telegraph. 



M. Trouve, 6, Rue Therese, Paris. 



This apparatus is characterised by the junction into one single object of the 

 three parts which constitute a telegraphic post, viz., the monitor, the manipu- 

 lator, and the reflector ; and also by the smallness of its size, which enables 

 a man to carry it on his back, with its cable, like a soldier's knapsack. To 

 this apparatus are joined four time-pieces ; the first two are tellers trans- 

 mitting the despatch by sound. The two others have dials, movable and 

 printed on both sides ; the one has letters and figures, the other letters only, 

 with blanks for tracing words, which allows of orders being sent as rapidly as 

 by word of mouth. 



FUZES. 

 (a.) WIRE OR Low TENSION ELECTRICITY FUZES. 



1712. Earliest form of Fuze used by the Royal Engineers 

 for the explosion of mines by electricity (first used in removing the 

 wreck of the " Royal George," Spithead, 1839). 



F. A. Abel, F.R.S. 



