370 



SEC. 10. ELECTRICITY. 



I667a. Arm of Insulators, for land wires. 



Warden, Mtiirhead, and Clark. 



No. 1. Andrews white porcelain, j 



ordinary, No. 8. 

 No. 2. Andrews white slot and 



hole at top. 



No. 3. Andrews white slot. 

 No. 4. Do. brown, No. 8. 

 No. 5. Do. do. No. 11. 

 No. 6. Do. stoneware, No. 8. 

 No. 7. Brown porcelain, Post 



Office pattern. 



No. 8. Clark's invert insulator. 

 No. 9. Spanish. 

 No. 10. New South Wales. 



No. 1 1. Spanish larger hook. 



No. 12. Varley's, No. 8. 



No. 13. Indian Pattern. 



No. 14. Warden's. 



No. 15. Relays, No. 11. 



No. 1G. U shackle. 



No. 17. Wardens perforated iron 



hook for iron poles. 

 No. 18. 2 insulator. 

 No. 19. Bell hood (small). 

 No. 20. Do. (large). 

 No. 21. Bright's shackle. 



1667b. Arm, with eleven Insulators. 



Warden, Muirhead, and Clark. 



1667c. Arm, with fourteen Insulators. 



Warden, Muirhead, and Clark. 



1669. Submarine Telegraphic Cables. Geminiano Zanni. 



In the above specimens the conductor (consisting of one or more copper 

 wires) is enclosed within a series of soft iron wires, which unite to form a 

 strand or core by passing the combined series of wires through a bath of 

 molten tin, or any other comparatively soft metal. The core thus combined 

 into a solid body is protected from corrosion. It is then coated with gutta 

 percha, or any insulating material, over which tin foil is wrapped to exclude 

 moisture. A band of hemp (immersed in tar) is wound round the core to 

 protect the metal foil from injury or corrosion. 



1670. Ward's Dead Beat Telegraph. 



William Sykes Ward. 



Two delicate coils of fine wire are suspended on points around the poles of 

 powerful permanent magnets ; the motions are limited so as to give distinct 

 indications without tremulous vibrations. Patented in 1847. 



1671. Signalling Key for Telegraphy, to send into a line 

 positive or negative currents. Elliott Brothers. 



167 la. Small registering Electro-Magnet, capable of 

 supplying 500 signals per second. 



Marcel Deprcz, 16, Rue Cassine, Paris. 



1675. Apparatus for sending simultaneously in opposite 

 directions Telegraphic Despatches, between two stations with 

 one single wire in the line. 



Elic Warimann, Professor of Natural Philosophy at the 



University of Geneva. 



A full description is to be found in the number for March 1856 of the 

 " Bibliotheque universelle de Geneve." The keys, when worked, close two 

 different circuits, which are to be of such directions and intensities that they 



