American telegraphy and encyclopedia of the telegraph; systems, apparatus, operation (1909)
Maver, William, jr. [from old catalog] · New York, Maver publishing company · leaf 435
ree or 3. The ear and not the watch is tobe relied upon for the intervals. For signaUng with flash lantern, heliograph or search-light shutter, same as infog signals; substitute short flash for toot, and long steady flash forblast. The elements of a letter should be slightly longer, TO SIGNAL WITH…
Telegraph
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