The telegraph manual: a complete history and description of the semaphoric, electric and magnetic telegraphs of Europe, Asia, Africa, and America, ancient and modern.

THE SECOND MECHANICAL TELEGRAPH. 191
netism required for moving the detent of the mechanism. His
experiments were not, to him, satisfactory, and he sought the
advice of Prof. Faraday, and then Dr. Roget. This latter gentleman referred him to Professor Wheatstone, of King's College. Mr. Cooke lost no time in making the acquaintance of
Prof. Wheatstone, which took place on the 27th day of February, 1837. The two gentlemen discussed the subject of telegraphing, freely, and Prof. Wheatstone exhibited to Mr. Cooke
Fig. 14. Fig 15..4%
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n a w h bn uig in his e i s
an apparatus which he had been using in his experiments on
the effects of electric currents in deflecting magnetic needles.
To open and close a circuit, Prof. Wheatstone had arranged
two very ingenious contrivances, which he called " permutating
key boards."