This section is from the book "Cyclopedia Of Architecture, Carpentry, And Building", by James C. et al. Also available from Amazon: Cyclopedia Of Architecture, Carpentry And Building.
The meter should be placed in such a position that it is easily accessible and may be read without the use of an artificial light. It is connected into the system between the service pipe and main riser to the building, the connections being made as shown in Fig. 67.
Different meters vary but little in the arrangement of the dials. In large meters there are often as many as five dials, but those used for dwelling houses usually have but three. Fig. 68 shows the common form of index of a dry meter. The small index hand, D, on the upper dial is not taken into consideration when reading the meter, but is used merely for testing. The three dials, which record the consumption of gas, are marked A, B and C, and each complete revolution of the index hand denotes 1,000, 10,000 and 100,000 cubic feet respectively. It should be noted that the index hands on the three dials do not move in the same direction;
A and C move with the hands of a watch, and B in the opposite direction. The index shown in Fig. 68 should be read 48,700. Suppose after being used for a time, the hands should have the position shown in Fig. 69. This would read 64,900, and the amount of gas used during this time would equal the difference in the readings: 64,900 - 48,700 = 16,200 cubic feet.