To satisfy one's self that the gas company does not make a mistake in reading the meter, it is well for the consumer, occasionally at least, to read his meter at as nearly as possible the same time that the gas company reads it. Usually the gas company's bill will state the meter readings on the dates between which the bill applies, so that checking meter readings will be easy. If the meter readings are not given on the bill, the consumer can determine what the amount of his bill should be if he knows the meter readings and the price of gas per thousand cubic feet. Should the consumer take one meter reading at the proper time and then miss the next one or two, it is obvious that he can still check up the gas bills by taking a reading at the next convenient time when the company's reader calls, calculating the cost of gas used between the dates of his readings and comparing this cost with the sum of the amounts of the bills rendered for gas between the same dates. If a consumer's gas bill for a certain period greatly exceeds that of the previous period, it is due to one or more of the following

causes:

(a) An increased consumption of gas.-A careful consideration of the use made of gas during the period covered by the bill will very often reveal the fact that an unusual amount of gas has been consumed. Baking, canning of fruit, entertaining, the coming of long winter evenings, etc., are a common cause of increased gas consumption resulting in larger bills than usual. Leaks in the gas pipes of the house may produce the same results.

(b) An error of the gas company in reading the meter or in office work. If the consumer reads his own meter and checks the bill, the question as to whether this cause is operative can be quickly ascertained.

(c) A fast meter.—If causes (a) and (b) apparently do not exist, the consumer will naturally consider that his meter is fast.

The best procedure for the consumer who thinks that his meter is incorrect varies with the locality. Many of the larger cities are provided with meter-inspection departments, under the supervision of the city or State, and the consumer can have his meter tested by this department. If his meter is found to be fast in excess of the established tolerance, the company usually pays the fee for the test and refunds to the consumer a certain amount, depending

upon the magnitude of the error of the meter and the probable length of time that the consumer has been thereby overcharged. If the meter is found to be within the tolerance, or "slow," the consumer usually pays the fee (about $1), and may have to pay the gas company for the probable amount he has been undercharged. The fact that it is so difficult for a consumer to know when his meter registers correctly, since he can not check up the amount of gas delivered to him as he can check up the amount of groceries bought, makes it especially evident that every community of gas consumers should have a meter-inspection service available, where meters may be tested by or under the supervision of a public official.

VII. WATER

1. Measurement of Household Water Supply

Water, when not sold at a flat rate without direct measurement, is usually sold at so many cents per thousand gallons, and the

quantity used by each consumer is measured by meter. The water meter is located in the supply line from the water main to the consumer's premises and is either placed indoors where the service enters the house or outside underground in front of the consumer's house in a box or manhole provided with a cover at the ground level for easy access.

No

water can reach the

consumer except by

passing through the

meter, and all water passing through the meter is recorded whether it be used or wasted through leaks or otherwise.

2. Water Meters

The principle is very similar to that of gas meters, described above. An example of the commonest type of meter for measuring water for domestic use, the disk type, is illustrated in Fig. 42. Fig. 43 shows a water meter cut in two so as to show the working parts, and Fig. 44 shows the part of the meter which actually does

the measuring, called the measuring chamber, separately, with the cover removed so as to show the disk in position and the circular chamber in which it moves.

The interior of the meter case (see Fig. 43) is divided into three compartments, one at the top, which the water can not reach, containing the register or mechanical counter, provided with a dial (see Figs. 45 and 46) facing upward, which is read from the top by lifting back the little cover at the top; one at the bottom, containing the moving piston; and one between the two containing some small gear wheels, whose only use is to reduce the motion

of the piston in the lower chamber and communicate it to the counter above. The left-hand threaded end is the inlet, and to it is screwed the pipe from the water main; the righthand end is the outlet and leads to the consumer's service pipe. The course of the water through the meter is indicated by the arrow,

FIG. 43.-Interior view of a water meter, showing working parts

entering at the left, passing upward through a screen intended to keep dirt and scale from the working parts, to the middle compartment, then downward around the measuring chamber and out at the right.

The way the meter operates is more clearly seen from Fig. 44. The disk of rubber composition is mounted on a ball working in sockets at the top and bottom of the chamber and just touches the sides of the chamber all the way round, dividing it into an upper and lower compartment. On one side is a thin partition extending halfway across and passing through a slot in the disk.

The disk does not rotate, but has a motion similar to that of a coin which has been spun on edge and is coming to rest, tilting around its edge.

In the position shown in Fig. 43 the water will enter from above, as shown by arrow at one side of the partition (shown at the right in Fig. 43), flow under the disk, tilting the back edge of the disk upward as it moves around and the opposite edge

FIG. 44. Measuring chamber of a water meter

downward, forcing water out through the lower opening at the rear side of the partition, as shown by the arrow. Water enters above the disk in a similar manner; while one compartment is filling another is emptying, making the flow continuous. The end of the spindle projecting upward from the disk is given a circular motion. In revolving it pushes around a little lever (Fig. 43) attached to the spindle of the gears in the middle com