The indicating mechanism he now devised was electrical, controlled at
central by two circuit-closing keys, and was a prototype of all the
later and modern step-by-step printing telegraphs, upon which the
distribution of financial news depends. The "fraction" drum of the
indicator could be driven in either direction, known as the advance and
retrograde movements, and was divided and marked in eighths. It geared
into a "unit" drum, just as do speed-indicators and cyclometers. Four
electrical pulsations were required to move the drum the distance
between the fractions. The general operation was simple, and in
normally active times the mechanism and the registrar were equal to all
emergencies. But it is obvious that the record had to be carried away
to the brokers' offices and other places by messengers; and the delay,
confusion, and mistakes soon suggested to Doctor Laws the desirability
of having a number of indicators at such scattered points, operated by a
master transmitter, and dispensing with the regiments of noisy boys.
He secured this privilege of distribution, and, resigning from the
exchange, devoted his exclusive attention to the "Gold Reporting
Telegraph," which he patented, and for which, at the end of 1866, he had
secured fifty subscribers. His indicators were small oblong boxes, in
the front of which was a long slot, allowing the dials as they travelled
past, inside, to show the numerals constituting the quotation; the dials
or wheels being arranged in a row horizontally, overlapping each other,
as in modern fare registers which are now seen on most trolley cars. It
was not long before there were three hundred subscribers; but the very
success of this device brought competition and improvement. Mr. E. A.
Callahan, an ingenious printing-telegraph operator, saw that there
were unexhausted possibilities in the idea, and his foresight and
inventiveness made him the father of the "ticker," in connection with
which he was thus, like Laws, one of the first to grasp and exploit the
underlying principle of the "central station" as a universal source