ns of which, through the employment of suitable devices, messages may
be stamped in or upon a paper tape, transmitted through automatically
acting instruments, and be received at distant points in visible
characters, upon a similar tape, at a rate twenty or more times
greater--a speed far beyond the possibilities of the human hand to
transmit or the ear to receive.

In Edison's system of automatic telegraphy a paper tape was perforated
with a series of round holes, so arranged and spaced as to represent
Morse characters, forming the words of the message to be transmitted.
This was done in a special machine of Edison's invention, called a
perforator, consisting of a series of punches operated by a bank of
keys--typewriter fashion. The paper tape passed over a cylinder, and
was kept in regular motion so as to receive the perforations in proper
sequence.

The perforated tape was then placed in the transmitting instrument,
the essential parts of which were a metallic drum and a projecting arm
carrying two small wheels, which, by means of a spring, were maintained
in constant pressure on the drum. The wheels and drum were electrically
connected in the line over which the message was to be sent. current
being supplied by batteries in the ordinary manner.

When the transmitting instrument was in operation, the perforated tape
was passed over the drum in continuous, progressive motion. Thus, the
paper passed between the drum and the two small wheels, and, as dry
paper is a non-conductor, current was prevented from passing until a
perforation was reached. As the paper passed along, the wheels dropped
into the perforations, making momentary contacts with the drum beneath
and causing momentary impulses of current to be transmitted over the
line in the same way that they would be produced by the manipulation
of the telegraph key, but with much greater rapidity. The perforations
being so arranged as to regulate the length of the contact, the result
would be the transmission of long and short impulses corresponding with
the dots and dashes of the Morse alphabet.

The receiving instrument at the other end of the line was constructed
upon much the same general lines as the transmitter, consisting of a
metallic drum and reels for the paper tape. Instead of the two small
contact wheels, however, a projecting arm carried an iron pin or stylus,
so arranged that its point would normally impinge upon the periphery of
the drum. The iron p