American telegraphy and encyclopedia of the telegraph; systems, apparatus, operation (1909)
Maver, William, jr. [from old catalog] · New York, Maver publishing company · leaf 612
HALL RAILWAY HLOCK SYSTEM—THEORY. ff the wires w,W become crossed, that will, by diverting current from km, place tnesignal at danger also. 502 AMERICAN TELEGRAPHY The relay r and the magnets are placed in any suitable place.One of the track instruments is shown in cross section in Fig. 377. In…
Telegraph
Internet Archive · Library of Congress · Public Domain Mark 1.0. Free to use for anything.
![An illustration from [Graphophone patents] (1878)](https://img.insideoutlibrary.com/img/200/ia-graphophonepaten10unit-125-106.webp)
