Bunnell Army Field Telegraph Set & Balanced Double Relay

15A       This is a gem, a compact beauty. Where most combination sets are 7 to 7.5 inches wide, this one is only six. The sounder has a resonator sub-base like that of 9B, but here the main base of the sounder is extended to carry the key.

      Unlike the sounders shown on pages 8 and 9, this one is a main line sounder. That is, it is of high resistence and may be cut directly into a main telegraph line. (In the railroad trade it would be referred to as a calling sounder.)

      The spring tension adjustment is old fashioned. Turning the knob at the stop standard wraps the string around the horizontal shaft.

15B       The polished brass case raises two points. First, the case is lacquered. One of the highly touted factors among makers of brass instruments around the turn of the century was the "gold lacquer" they used to prevent tarnishing and add a golden glow. Their formulations and sources of supply for the ingredients were highly guarded trade secrets.

      Second, the company name appears on the case in the illustration. It appears, in fact, on almost every illustration in one form or another. You won't find it on the instruments shown in the drawings. It will, however, be stamped into a key lever (6A), on a metal name tag (10), or pressed into the wood of some wood-based instruments.

15C       An important use for telegraph-type circuits was for fire alarm systems. This is one of the two items in this catalog (the other is 12B) which have non-communication applications.