Appletons' cyclopaedia of applied mechanics: a dictionary of mechanical engineering and the mechanical arts (1880)
D. Appleton and Company, Benjamin, Park, 1849-1922 · New York, D. Appleton · leaf 806
In this way the disk will take alternately a parallel orperpendicular position to the track. A track instrument,shown in Fig. 3941, which is a circuit-closer, is placedunder a rail, and during the passage of a train closes acircuit, momentarily exciting the electro-magnet of thesignal apparatus. As…
Mechanical engineering -- Dictionaries
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