The standard electrical dictionary : a popular encyclopaedia of words and terms used in the practice of electrical engineering (1898)
Sloane, T. O'Conor (Thomas O'Conor), 1851-1940 · London : Crosby Lockwood and Son · leaf 412
Fig. 257. Perforator for Wheatstones Automatic Telegraph, Perforators may be entirely mechanical but are sometimespneumatic, compressed air being used to operate them. The holesthey make are on different levels of the paper strip, as shown inthe cut. Period. The time required for the completion of…
Electricity
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