omething;
whereas, person No. 1 and person No. 5 in the row might read the time
respectively 29 and 31 minutes past something. Operators far to the
right or to the left of a clock will get different readings, and an
operator below a clock will get different kinds of readings at different
times and correct readings at few times.

Timing Machines:--Machines which record time directly on long-distance
tickets are of value and machines which automatically compute the time
elapsing during a conversation are of much greater value. The
calculagraph is a machine of the latter class. The use of some such
machine uniformly reduces controversy as to time which really elapsed.
Parallax errors are avoided. The record possesses a dignity which
carries conviction.

[Illustration: Fig. 453. Calculagraph Records]

Calculagraph records are shown in Fig. 453. In the one shown in the
upper portion of this figure, the conversation began at 10.44 P.M. This
is shown by the right-hand dial of the three which constitute the
record. The minutes past 10 o'clock are shown by the hand within the
dial and the hour 10 is shown by the triangular mark just outside the
dial between X and XI.

The duration of the conversation is shown by the middle and the
left-hand dials. The figures on both these dials indicate minutes. The
middle dial indicates roughly that the conversation lasted for a time
between 0 and 5 minutes. The left-hand dial indicates with greater
exactness that the conversation lasted one and one-quarter minutes.

The hand of the left-hand dial makes one revolution in five minutes; of
the middle dial, one revolution in an hour. The middle dial tells how
many full periods of five minutes have elapsed and the left-hand dial
shows the excess over the five-minute interval.

The lower portion of Fig. 453 is a similar record beginning at the same
time of day, but lasting about five and one-half minutes. As before, the
readings of the two dials are added to get the elapsed time.

[Illustration: Fig. 454. Relative Position of Hands and Dials]

The right-hand dial, showing merely time of day, stands still while its
hands revolve. The dies which print the dials and hands of the middle
and the left-hand records rotate together. Examining the machine, one
finds that the hands of these dials always point to zero. The middle
dial and hand make one complete revolution in an hour; the left-hand
dial and hand, one in five minutes. In making the rec