od as a perfection by Edison of many antecedent devices going back,
perhaps, much further than the legendary funnels through which Alexander
the Great is said to have sent commands to his outlying forces. The
improved Edison megaphone for long-distance work comprised two horns of
wood or metal about six feet long, tapering from a diameter of two feet
six inches at the mouth to a small aperture provided with ear-tubes.
These converging horns or funnels, with a large speaking-trumpet in
between them, are mounted on a tripod, and the megaphone is complete.
Conversation can be carried on with this megaphone at a distance of
over two miles, as with a ship or the balloon. The modern megaphone
now employs the receiver form thus introduced as its very effective
transmitter, with which the old-fashioned speaking-trumpet cannot
possibly compete; and the word "megaphone" is universally applied to the
single, side-flaring horn.

A further step in this line brought Edison to the "aerophone," around
which the Figaro weaved its fanciful description. In the construction
of the aerophone the same kind of tympanum is used as in the phonograph,
but the imitation of the human voice, or the transmission of sound,
is effected by the quick opening and closing of valves placed within
a steam-whistle or an organ-pipe. The vibrations of the diaphragm
communicated to the valves cause them to operate in synchronism, so that
the vibrations are thrown upon the escaping air or steam; and the result
is an instrument with a capacity of magnifying the sounds two hundred
times, and of hurling them to great distances intelligibly, like a huge
fog-siren, but with immense clearness and penetration. All this study
of sound transmission over long distances without wires led up to
the consideration and invention of pioneer apparatus for wireless
telegraphy--but that also is another chapter.

Yet one more ingenious device of this period must be noted--Edison's
vocal engine, the patent application for which was executed in August,
1878, the patent being granted the following December. Reference to
this by Edison himself has already been quoted. The "voice-engine," or
"phonomotor," converts the vibrations of the voice or of music, acting
on the diaphragm, into motion which is utilized to drive some secondary
appliance, whether as a toy or for some useful purpose. Thus a man can
actually talk a hole through a board.

Somewhat weary of all this work and excitemen