American telegraphy and encyclopedia of the telegraph; systems, apparatus, operation (1909)
Maver, William, jr. [from old catalog] · New York, Maver publishing company · leaf 107
ose whichwill be stated presently. A series of peculiarly shaped flat m^tal springs, termed spring-jacks are placedat the foot of the board, one spring-jack under each strap. In some cases two seriesof such spring-jacks are placed under the board, two jacks under each verticalstrap. A board thus… … ^ i^ l^ i®) ^ > A series of such spring-jacks arranged on a separate board is shown in Fig. 60.In that figure a spring-jack wedge is shown in position. The wedge is usuallyformed of two flat, metal strips, insulated by a hard rubber strip from each other.The upper strip is shown at b; the under…
Telegraph
Internet Archive · Library of Congress · Public Domain Mark 1.0. Free to use for anything.
![An illustration from [Electric engineering.] (1902)](https://img.insideoutlibrary.com/img/200/ia-electricengineer03inte-264-153.webp)
