glass oil cup of the inverted pattern, and is readily obtained from dealers in steam fittings. As these cups are furnished with pipe threads, the ease with which such a device is rigged up is evident. The connection between the cross and the glass tube is made by means of a rubber stopper, and to obtain a tight joint, the threads of that branch of the cross are bored out. The opening of the oil cup must be made at least " larger than the external diameter of the glass tube. The

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upright nipples shown in the sketch are furnished with the standard male threads of a meter; a set of these nipples corresponding to different sizes of meters should be provided. In making the test, all that is necessary is to substitute the tester for the meter.

90. Inside Piping. Almost all architects' specifications. now call for the piping in a building to be done according to the rules of the Gas Company, and the Gas Company usually adopts such rules as will insure that the size of the pipe used will be of ample capacity to carry the amount of gas it is expected will be needed with a differential pressure not exceeding 1⁄2" of water. They also specify that the work shall be done in such a manner as to insure, as far as possible, the safety of the occupants of the building. The following rules for the size of pipe for inside piping were adopted by the American Gas Light Association in 1898:

No greater length of pipe should be used than is given in the table, e. g., the maximum length of 1-inch pipe allowable under any circumstances is 70 feet, and it should not be expected to carry over 127 cubic feet of gas per hour.

One of the Natural Gas Companies where gas is largely used for fuel has adopted the following rules governing the size of the pipe and the method of installation:

All new piping must be tested with a mercury gauge and shall be made tight at a pressure of not less than 4 lbs. or 8 inches of mercury. No Spring gauges will be allowed. The Gas Co. must be notified of the completion of any job so that they may inspect the same should they deem it necessary.

The Riser pipe in any building shall not be less than 3/4-inch, and must go up in an inside partition wall and out of reach of frost, and must not project more than 2 inches below the cellar joist. No traps in the riser will be allowed.

Drop or bracket outlets must be securely fastened. Split pipes must not be cemented, but the pipe must be taken out and a perfect piece substituted. No cast iron fittings will be allowed, only the best malleable iron fittings galvanized.

In case more than one consumer wishes to use gas in a building a separate riser must be run for each consumer. In no case will a meter be set where the gas passing through that meter must be deducted from another meter through which it has previously passed.

Piping shall be so arranged that the meter can be placed in a position easy of access and exposed to neither dampness nor extreme heat or cold. The meter should be placed as near where the service enters the building as possible.

Suspended pipe must be securely fastened. No strings, rope or wire should be used.

In addition to the above, the following notes may be of interest.

For this work it is advisable to use the best quality of wrought iron pipe obtainable as this insures that the threads will be cut without stripping and there will be less liability of split pipe. The fittings used are preferably malleable iron, beaded, and the best practice is to use galvanized fittings since the galvanizing has a tendency to fill up whatever sand holes or porous places there might have been in the original casting. For the dope on the threads any one of the various compositions given under "Wrought Iron Main Laying" may be used on male thread only.

Care should be especially taken that all openings are securely fastened. There is now on the market a malleable iron drop fitting having lugs or ears projecting from the side

for the purpose of fastening. The use of this fitting makes it easier to fasten the drop and would also prevent the liability of the drop being unscrewed when the fixtures are taken off. No unions should be allowed to be used as it is almost impossible to make the work come so exact that the two faces of union will press against each other, making a tight joint without the use of a washer, and unions with which the joint is made by a washer are much more liable to become leaky than long screws. The long screws are cheap and make a joint that is tight or as permanently tight as any other joint.

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91. Testing Inside Piping. After the piping has been completed, it should be tested to see that it is perfectly tight. It is customary for the plumber to first ascertain if his job is tight, and after making sure that this is the case, to ask the Gas Company's inspector to make the final examination. The plumber should see that all openings are carefully closed with caps, and that the foot of the riser line is stopped. at any convenient side light attach an ordinary gas fitter's pump and mercury gauge. This mercury gauge should have a column of 15 to 20 inches in length. Air is forced into the piping by means of the pump until the mercury column has been forced up about 10 inches high in the gauge, the pump is shut off. If the mercury falls, there is a leak in the pipe; if it remains stationary, the pipe is tight. It is customary to require that the mercury remain stationary for from 15 minutes to half an hour. If the mercury falls rapidly, it will indicate that there is quite a leak, and this leak will be heard blow. If the leak is caused by a piece of split pipe or split fitting, the pipe or fitting should be removed and a new piece substituted. Gas fitter's cement should not be used for repairing leaks. If the leak can not be heard blowing, ether may be put into the hose of the air pump, and the pumping of the air into the pipes will carry the ether into the pipe. The odor of the ether escaping will indicate where the leak may be found in the pipe, and it may be definitely located by means of a strong soap water applied with a brush or sponge. The liquid is rubbed over suspected joints or fittings, and air bubbles are

blown by the escaping air. In very large work it is advisable to prove one floor or one section at a time and, when all are done, connect them with the riser and prove as a whole. If the pipe to be tested has been previously used for gas, and you have to test for leaks, it will be necessary to take off the meter and cap the bottom of the riser, also to take off the gas fixtures and cap the outlets carefully, as it is impossible to test pipe with the fixtures on and find it tight. The ground joints in the stop cocks of the fixtures almost always leak when the pressure is put on them. Sometimes plumbers, when they have a small leak and are unable to find it or if it is concealed in a partition where it is impossible to get at it to repair, will fill up the house piping with water containing salt or ammonia solution, hoping by this means to rust the leak tight. They are almost always successful in doing this, but the practice should be condemned, as, after the water has been drawn out of the pipe, the ammonia and salt still continue to rust the pipe, and in time this rust will collect in some one place and stop up the system.

Some gas companies require that the gas fitter file at the gas office a sketch or plan showing the size pipes run and the length of each piece. This plan is filed previous to inspection. The gas company's inspector checks up the sizes to see that they comply with the rule. He afterwards examines the piping in the house before it is concealed, and if the piping is according to the rules of the gas company, he gives a certificate to the effect that he has inspected and found it to be tight and to comply with the gas company's specifications. It is stated, however, in the certificate, that the issuing of this certificate does not insure its future soundness. At the time of the setting of the meter or at the time when the gas is turned on, a second inspection is made, this time of both the pipe and the fixtures, and in case these are found tight, the gas is turned on.

F. W. STONE, Chairman of Section.

MASTIN SIMPSON.

J. D. SHATTUCK.

GEO. C. HICKS, JR.

HENRY L. DOHERTY.

H. G. STILLSON.