Scarce circa 1860s lineman's pocket telegraph set, as used by spies during the Civil War. Measuring just 5″ x 2.25″ x 1.25″ in its hard rubber case, this is a complete ultra-portable telegraph sending and receiving system. During the Civil War, telegraph operator spies used these to tap into the enemy's communications systems: a bare wire tossed over uninsulated telegraph lines—and grounded with a bayonet—allowed them to intercept messages or send along false intelligence. This diminutive unit features horizontally mounted sounder coils, a 1.5″ strap telegraph key, and a tiny shorting switch; both the key and the switch have ivory knobs. The device is not marked by its maker.