A, bottom plate; B screw regulating supply to burner from gasholder, k ; c and D, two, out of three, tubes through which the gas if conducted to combustionchamber chamber, E; G, air-cone, regulating delivery of air to outside of flame; H, one of the wires which hold chimney: J, wire supporting globe; K, leathern gas-holder to which is attached valve, L, controlling admission of gas; M, support for shade.

Fig. 651.  Elevation of Wenham Lamp

Fig. 651.- Elevation of Wenham Lamp.

The Wenham gas-lamps are of this kind. The ordinary Wenham lamp, illustrated in Fig. 651, consists of a burner inclosed in a glass cup. The air-supply to the burner is drawn thiough the outer casing, and passes away along with the products of combustion through the inner tube back into the apartment. During the passage of the air to the burner, it receives heat from the inner tube, and is redelivered into the apartment in a highly-heated state. These lamps more nearly approach a gas-stove than any other fitting I know, and are, on this account, unsuitable for household lighting purposes, unless a special outlet flue is provided for the products of combustion, as shown in Fig. 652 The light itself is good and steady when properly regulated and governed, but this is of course the difficulty.

These lamps require to be cleaned occasionally, the inner tube at times being choked with soot, especially when the spreader of the burner is faulty, or the pressure and quality of gas unsuitable. When these lamps explode in lighting, the soot is loosened and the inner tube partially cleared, the soot floating about and settling on the various articles in the room. When by-pass taps are provided, there will be no explosion on lighting, but there is more probability of the inner tube being blocked with soot. They are most suitable for halls, . corridors, and other places where there is a free current of air.

A vertical section through the Wenham burner is given in Fig. 653. a is the actual burner of cylindrical form, held in position by the ring B; if this becomes loose, gas will leak inside and prevent the gas burning white. The button, if bent or made untrue, will also distort the flame. The gas enters at l and is heated in its passage through the spaces ff. The heated air passes through the gratings C C and G G and so impinges on both sides of the ring flame, which is shown by the dotted lines m m. It will be noticed that the flame is the lowest. part of the lamp, and consequently no shadow is cast downwards.

The incandescent gas-light pos-aesses great advantages over the older methods of illumination, and even over the electric light. It is claimed that (1) it saves half the gas required for ordinary burners, whilst giving at least three times the light; (2) the reduced consumption of gas results in a. perforated porcelain cylindrical burner; B, ring holding the burner in position; c, perforated disc; D, perforated button; E. rod supporting the button; r, way for gas; G. perforated dome; H, ring for supporting globe, secured by a bayonet catch; J, reflector. K, external cylinder; L. gas-supply pipe; M, the flame.

Fig. 652   Wenham Ventilating Lamp.

Fig. 652 - Wenham Ventilating Lamp.

A, iron ceiling-box; B outlet for vitiated air, etc. from lamp; C. sheet-Iron outlet shaft to flue; D, gas supply pipe; E., non-conducting material around box and shaft less carbonic acid and less heat being generated than with ordinary burners; (3) the burner being on the bunsen principle, and being so constructed as to ensure perfect combustion, is almost smokeless. There are now several rival incandescent burners, but the Welsbach is still the best.1

Fig. 653.   Vertical Section through the enham Burner.

Fig. 653. - Vertical Section through the enham Burner.

The "C" Welsbach burner gives a light of about 60 candle-powers, with a consumption of 3 cubic feet of gas per hour. The ordinary open-flame gas-burner gives about 15 candle-powers, with 7 cubic feet of gas per hour. The illumination from the incandescent gas-burner is therefore about four times greater, whilst using only one-half the gas.

With the common type of gas-burner there is practically no expense in first cost and maintenance, but from the figures given it will be seen that the payment for the gas passing through them is altogether out of proportion to the quantity of light obtained. It would require four ordinary gas-burners, each consuming 7 cubic feet per hour, a total of 28 cubic feet per hour, to equal the illumination from one "C" incandescent burner, consuming 3 cubic feet per hour. The extra cost of the incandescent gas-burners, together with the renewals of mantles, chimneys, and globes,2 will be saved in from one to two years according to the amount of gas consumed. When compared with the best regenerative systems of gas-lighting, the incandescent light does not show so large a saving. In order to get a light of 280 candle-powers, with gas at three shillings per thousand cubic feet -

With plain burners the cost would be about 4d. per hour.

"

argand

"

"

"

3d.

"

"

regenerative

"

"

"

ld.

"

"

incandescent

"C"

burners

"

9/16

"

1 Experiments by Prof. W. Wedding, of Berlin, on the relative value of five different incandescent burners, were published in the Journal for Gasbeleuchtung for 1895, and the following table contains an abstract of the results. The table is interesting not only for purposes of comparison, but also because it shows the gradual deterioration of even the best mantles.

Table XXXIX A. Comparison Of Incandescent Gas-Burners

Name or Burner.

Consumption of Gas PER HOUR.

ILLUMINATING POWER

When first lighted.

After Of hours' use.

When first lighted

After tax hours use.

cub. ft.

cub ft

candles

candles

Auer (Welsbach)...............

3.81

57.3

38.4

Trendal ...............

3.67

3.85

201

13.2

Benas ...............

874

3.88

23.6

64

Stobwasser ...............

Ml

Ml

31.6

4.0

Kramme .....................

860

Ml

227

M

Further particulars of the experiments will be found in The Proccedings of the Institution of Civil Engineers, VoL CXXI., Part III. - Ed.

2The number of breakages is very largely reduced when the burners are sespended from springs and the gas Admitted by flexible tubes, as in the A.V.I.L. apparatus; this is now Adapted for brackets as well as for pendants. - ED.