Discoveries and inventions of the nineteenth century (1905)
Routledge, Robert · London : G. Routledge and Sons · leaf 620
a shape that contact is alternately made and brokenas the projections and spaces pass it. It is obvious that the needle of theindicator will therefore advance over the same letters as the index of thecommunicator. A very elegant dial instrument has been invented by Sir Charles Wheat-stone, in which… … Fig. 291.— Wheatstone^s Universal Dial Telegraph. into thirty equal spaces, in which are the twenty-six letters of the alphabet,three punctuation marks, and a +. In an inner circle are two series ofnumerals and other signs. About the circumference of the dial are thirtysmall buttons or projecting…
Inventions
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