Source : Webster's Revised Unabridged Dictionary (1913)

Telharmony \Tel*har"mo*ny\ [?]), at a distant point or points by
   means of alternating currents of electricity controlled by an
   operator who plays on a keyboard. The music is produced by a
   receiving instrument similar or analogous to the telephone,
   but not held to the ear. The pitch corresponds with frequency
   of alternation of current. Telltale \Tell"tale`\, n.
   1. A thing that serves to disclose something or give
      information; a hint or indication.

            It supplies many useful links and telltales.
                                                  --Saintsbury.

   2. (Railroads) An arrangement consisting of long strips, as
      of rope, wire, or leather, hanging from a bar over
      railroad tracks, in such a position as to warn freight
      brakemen of their approach to a low overhead bridge.