"If the house is an old one, or has been finished, and you have to test for leaks, take off the meter and cap the bottom of the riser; also unhang the gas fixtures and remove the brackets and cap all outlets carefully. Then use ether and locate leaks before tearing up floors or breaking plaster.

"Occasionally, when a gas fitter cannot get a job tight, there is a possibility he may cut off the part or floor of the building he cannot get sufficiently tight to suit the inspector's idea of perfection. The inspector can only prove such practice by removing or slacking off a cap here or there about the house if he suspect such an attempt. If no air escapes, then he has the dead end."

A

Whenever a meter is set the piping should be tested by closing all outlets on the piping, and turning gas into the meter. movement of the test hand indicate a leak.. (Trustees.)

10. Give a description, illustrated with sketches, of a Welsbach gas burner, and state how you would adjust air and gas so as to get the greatest amount of light with the proper consumption.

Ans. The Welsbach burner belongs to that class of lighting devices commonly known as Incandescent Gas Burners, in distinction from the Open Tip or Open Flame Burners, and is a burner in which the source of light is not one of the component parts of the gas itself, heated to incandescence by another part of the gas, but is a foreign body introduced into the flame (which is perfectly non-luminous) and heated till it glows.

"The Welsbach burner consists primarily of a Bunsen burner and a mantle; the gallery, air-shutter, chimney, etc., being added to give it practical value for general lighting purposes.

"The mantle is made by saturating a web of cotton thread in a fluid holding in solution salts of the rare earths, thorium and cerium. It is given the proper shape by stretching over wooden forms and is sewed at the top to the support with platinum wire. The cotton is then burned out, leaving an exact reproduction of the web by the oxides of the earths.

"Referring now to the cut and taking up the parts in order

we find first the Bunsen tube which screws on to the gas fixture. This can be divided into three parts, the base, the check and the tube proper. The check is held in the base by the tube screwing down on it and is made in different forms. One consists of a flat piece of brass in which are three small holes. These holes are of different sizes for different pressures of the gas supply, those for a two-inch pressure being smaller than those for a one-inch pressure, the object being to keep the amount of gas supplied to the burner as near three feet an hour as possible. This form of check can only be adjusted. to one particular pressure and will not give as good results at any other pressure. In case of very high pressures a check with one hole is sometimes used. This check is not flat, but is slightly coned with the hole at the apex.

"The form of check now in general use is that known as the adjustable' check, which has the advantage of being readily adjustable to any pressure within the limits ordinarily met with in practice, thus enabling the same check to be used. under varying pressures. The Bunsen tube with adjustablecheck is fully illustrated in the second cut.

"Figure 1 shows the Bunsen tube complete; Figure 2 shows the upper part of the tube, A, unscrewed from the lower part of the tube, B, and with the adjustable parts removed. The assembled adjustable parts, which can be lifted out of the base of the tube, are shown in Figure 3. Figure 4 is a plan of the complete tube, and Figure 5 is a plan of the adjustable parts.

"In detail, the adjustable parts consist of a thimble, E, perforated on the top with three circumferential slots, K, K, K, Figure 4. On top of this thimble is a plate, F, one side of which is extended to form a handle, C. This plate, F, is perforated with 11 holes, arranged in groups of 4, 4, and 3, as shown in Figure 5 at L, L, and L1. There are three sizes of holes, and one hole is omitted from one of the groups, so that gas will be admitted through but two holes, when necessary, as in cases where high pressure is met with. This plate, F, makes a gas-tight joint with the thimble, E, being held down to the latter by means of a spider, G, and screw, H, Figure 3. A ring, D, is riveted to the lever, as in Figures 1 and 3.

"If the pressure is high, the lever is turned clock-wise to its extreme position. In this case the slots in the thimble are entirely shut off with the exception of but 2 holes in the plate. If the pressure is low, the lever is moved counterclock-wise, so that more holes are uncovered; and the extreme position allows gas to pass through the three sets of holes, as shown in Figure 4.

"The office of the air-shutter is to regulate the supply of air admitted to the tube for mixture with the gas to make the Bunsen flame. If the gas is rich, more oxygen is necessary for complete combustion than if it is poor, and the air-shutter must be opened wider in order that more air will be admitted.

"The gallery carries the mantle, shades and chimney. The mantle is mounted so that the lower part surrounds the cap, and is put in place by carefully lowering the support into the lug (not shown in the print), and tightening up the set screw.

"The central tube which fits over the Bunsen tube is a part of the gallery, and holds it in the proper position. It is enlarged at the top to a mixing chamber on which is placed the gauze held by the cap. This gauze assists in the mixture of the air and gas, and also prevents the flame flashing back.

"The frame of the gallery answers two purposes, it carries the shades and protects the mantle when the chimney is being taken off or put on. The shade-supports slip over the ends of the wires forming the frame and carry certain styles of shades ; when other shades are used they can be taken off.

"The bobesche-supports hold the bobesche or eye-screen, a small bowl-shaped shade which is used with the dome shade when the light is at such a height that the direct rays from the mantle are disagreeable.

"The chimney may be of glass or mica, the latter being preferable in situations exposed to draughts.

"The above is a description of the type of burner in general use. There are modifications of it for special cases, but they differ only in construction and not in principle."

The proper adjustment of air and gas is obtained as follows: Set the air-shutter so that the openings are about half open. Light the gas and see if any flame shows above the top of the mantle. If it does, turn the check lever clock-wise until the