348 SEC. 10. ELECTRICITY. 



1682. Double-Needle Instrument. As used by the Electric 

 Telegraph Company in 1846. Held Brothers, London. 



Used for all public business, and for the principal railway circuits, with 

 6-inch coils and astatic needles. The coils were afterwards reduced to one 

 inch. The double needle was superseded for public purposes by the Bain 

 recording instrument from about 1850. It is still used by some railway 

 companies. 



1683. Cooke and Wheatstone's Single-Needle Instru- 

 ment. (Early form.) J. A. Warwick. 



Used by the Electric Telegraph Company in 1846 on unimportant railway 

 circuits. 



The specimen exhibited has a " crutch " handle commutator, which was the 

 earliest form used ; later the " drop " handle was introduced. 



1508d. Two Photographs of the Telegraph Apparatus 

 used by Gauss and Weber. 



Physical Institute of the University of Oottingen (Prof. 

 Dr. Riecke). 



One or the photographs represents the magnetic inductor which serves 

 for giving the signals, the other the unifilar magnetic rod with multiplier 

 serving for receiving the signals. 



15O8. Two Original Drawings of plans, sections, and ele- 

 vations of machinery of Sir C. Wheatstone's proposed scheme for 

 a sub-marine telegraph cable, 1840. Robert Sabine. 



15O8a. Portion of the First Submarine Telegraphic 

 Cable. This cable was laid by Mr. T. R. Crampton, C.E., in 

 1851, and established the practicability of submarine telegraphy. 



Thomas Russell Crampton. 



Submarine telegraphy in 1851 was deemed by most engineers aud the 

 public to be visionary if not impracticable. 



Its extension over the whole world since its first practical introduction in 

 1851, has been immense, and its advantages incalculable. It was esta- 

 blished in the following manner : Various propositions were from time to 

 time put forth to effect the object, but few people were prepared to take 

 the risk until a company was formed having most influential men on the 

 direction, who advertised in the usual manner for subscriptions. Such, 

 however, was the want of confidence felt in the scheme, that only about two 

 per cent, of the necessary capital was subscribed, and this money was con- 

 sequently returned to the applicants. Notwithstanding this apathy of the 

 public some of the directors and their friends did not cease to entertain a full 

 conviction of its possibility, and they subsequently consulted Mr. T. R. 

 Crampton, C.E., on the subject, and offered to assist towards providing the 

 funds if he felt sufficiently confident of ultimate success. Mr. Crampton 

 undertook the entire charge and responsibility of the form, construction, and 

 laying of the cable, aud also took upon himself rather more than one half the 

 pecuniary risk, the other half of the money being found by Lord de Mauley, 

 Sir James Carmichael, Bart., Messrs. Davies Son and Campbell (the solicitors 

 of the Company), the Hon. F. W. Cadogan, and Mr. Haddon. 



The cable was in the same year (1851) successfully laid between Dover 

 and Calais by Mr. Crampton. 



