Perforator.
An apparatus used in automatic high speed telegraphy for perforating
strips of paper. These are then used by drawing between a roller and
contact spring for making and breaking the telegraphic circuit for the
production of a record, such as the Morse record, at the distant
receiving station.
The perforated strip has different classes of holes punched in it to
represent dots or dashes. It is fed by machinery very rapidly, so that
the message is transmitted with the highest speed. Several operators may
simultaneously prepare the paper strips, and thus in conjunction with
its rapid feeding in the transmitter, far surpass the time of ordinary
direct transmission.
Fig. 257. PERFORATOR FOR WHEATSTONE'S AUTOMATIC TELEGRAPH.
Perforators may be entirely mechanical but are sometimes pneumatic,
compressed air being used to operate them. The holes they make are on
different levels of the paper strip, as shown in the cut.
Period.
The time required for the completion of one complete element of periodic
motion. This may be a complete alternation (See Alternation, Complete)
of an alternating current, or of an oscillatory discharge.
Periodicity.
The rate of succession of alternations or of other fixed phases; the
rate of recurrence of phenomena.