[Illustration: Fig. 657.--Interior view of Thompson watt hour meter (type CQ). The capacities of this type range from 50 to 400 amperes inclusive, two wire, and 50 to 200 amperes inclusive, three wire, and for voltages of from 100 to 600 volts. These meters are made with either front or back connections. In front connected meters the positions of the leading-in wires and cables are the same as in the type C-6, fig. 654, so that either type of meter may be installed in the same location.] [Illustration: Fig. 658.--Specimen record from General Electric recording ammeter. The record is made on a band of specially prepared paper four inches wide and sixty feet in length. On this paper are ruled lines corresponding to time, and the instrument calibration. The lines ruled across the paper represent time; those ruled lengthwise represent volts, amperes, or watts, depending upon the instrument construction. This form of paper has the advantage of permitting the use of time divisions of equal length throughout the entire range of the recording pen. The recording pen is attached to the moving element in such a manner that its motion is transmitted in a straight line parallel to the time division on the chart. As the paper is unwound and passed under the recording pen, it is paid into a space at the bottom of the instrument case. To assist in removing paper, the instrument is provided with a stripper, which enables the paper to be torn off evenly and without damage. The paper feeding mechanism is simple. By means of suitable gearing, the clock drives a drum having peg teeth which engage the holes located near the edge of the paper. These teeth not only feed the paper under the recording pen, but also give it a definite and accurate position along the axis of the drum. The feeding drum is driven by a friction clutch.]