[Contributed by H. Y. Margary)

The particular means of illumination to be employed in any given building' is an important point constantly arising. As a rule both gas and electricity are available, and each have advantages not possessed by the other. In some cases it would be inadvisable to use gas, in others electricity would be deemed out of place, while a combination of both is occasionally preferable to either alone.

Considering only, for the moment, the conditions where a public supply of both illuminants is available, the following points of view arise :-

1. Cost of Installation. 2. Cost of Supply. 3. Suitability. 4. Fire Risk. 5. Health.

1. Cost Of Installation

Cost Of Installation. Keen competition has reduced the cost of an electric-light installation to a point very much in favour of the user, while the cost of gas installations has not greatly declined. This point goes rather to the advantage of electricity. The cost of wiring a 12-roomed house, say, for ordinary effects, and including fittings of simple character, would be approximately 25. Installing gas under similar conditions would cost 30. In like manner the relative costs would favour electricity for installations of any size, though with larger installations the difference would be less, as the cost for increased sizes of cable rises much more than that of larger sizes of gas barrel.

These figures are based on competition lines, but include installations which would meet the conditions and requirements of the various authorities concerned.

More elaborate methods of wiring would raise the cost of laying in the wires, but in the matter of fittings electricity would always be cheaper.

Prime cost, then, is not a very important point, and comparison would vary in effect according to the design of the building. For instance, it is demanded of electricity that each lamp or group of lamps shall be controlled from one or more central points, often some distance from the lamps they govern. Where there are long runs to the burner, gas would be the cheaper to install, simply because the user is content to turn on at or close to the burner.

2. Cost Of Supply

Cost Of Supply. Where cost is a matter for consideration, as is generally the case with ordinary dwelling-houses, the favour would be shown to gas. Were there no other disadvantages to be considered under this head, the electricity bill would be generally double that of the gas bill, although the opportunities for economy are much greater with the self-lighting illuminant and its easily handled switch.

This comparison is based upon gas at 2s. 8d. per 1000 feet, and electricity at 5d. per unit; the difference will of course vary with the local charges, becoming nil at one point and reversing in favour of electricity where gas is 2s. 6d. and the electricity is 2d. So far the advantage lies with gas as regards cost per annum, but the important point of the preservation of the interior decoration somewhat reduces this. Where electricity is employed, ceilings, which would otherwise require to be distempered every spring, will last for three or four years, and in like proportion paint work, pictures, and ornaments generally are saved from the ill effects of the acid fumes resulting from the combustion of coal gas.

The foregoing statement assumes that the smoke and fumes from the fire are efficiently carried away, and it should also be borne in mind that the difference is perhaps more apparent in the provinces than in London, where fogs and impure atmosphere have a considerable effect.

To sum up, the question of relative costs of supply is modified by redecoration. Gas will probably be cheaper in the ordinary dwelling-house, while electricity should be used where decorations are on elaborate and expensive lines; but in any case it must be remembered that the cost per annum for redecoration is at least three times as much where gas is used.

In the matter of upkeep, electricity compares favourably with incandescent gas; but would be more expensive compared with gas consumed by means of the ordinary jet.

Although the electric incandescent lamp gives off a fair amount of heat, a space lit by gas would be comparatively warmer. Advantage is taken of this difference wherever heat is essential, as in tobacconists' premises. On the other hand, the moist acid fumes from the gas-burner are, in such premises as those of gold and silversmiths, distinctly deleterious. In such cases the cost of supply is not so important.

3. Suitability

Suitability. There is little doubt that in point of "suitability" electricity has the advantage of gas, with a few exceptions briefly referred to in the last paragraph. Modern progress in the design of electric-light fittings and lamps enables any desirable effect to be easily obtainable. The soft warm light emanating from a gasalier containing a cluster of comparatively small gas jets and softened by opal or tinted globes is obtained at once by the simple artifice of frosting or tinting the glass of the electric-light bulb, while in design the artist has a much freer hand in developing an idea through the medium of an electrolier. It is scarcely possible to design an electric fitting which an electrician cannot supply with power, while the gasalier demands pipes and taps which, however cunning and skilful the designer, are bound to cramp his art to a considerable degree. Effective Louis Quinze candle fittings, for instance, which are practically impossible where gas is the only supply, are quite an easy matter for the electrician, and form a most admirable adjunct to the principal lighting of drawing-rooms, studies, or boudoirs; in fact, it is a question whether any central electrolier or pendant is really admissible in a modern drawing-room of ordinary size, now that there are so many exquisite wall fittings and shaded standards both for the floor and table.

Beautiful effects of modulated light simply become a matter of taste, unconfined by any limits when electricity is employed. There is no necessity to light the whole room with equal intensity to ensure sufficient light everywhere. On the contrary, this must be at the expense of certain items in the decorative scheme which might be better lit by "suggestion" than actually - that is to say, in any room furnished as much for beauty as utility, each distinctive point or piece in the scheme must be treated as its character demands. A piece of bold carving in dark material and of heavy design should, if possible, be illuminated from two or three places at the back or inside with lamps of low candle-power, and where the lamps themselves cannot be entirely hidden they should be enveloped in a glass flower or vase of suitable tint, or be suspended in some quaint eastern lantern in keeping or contrast with the design. It is possible by this means to greatly enhance the artistic value of such a piece of furniture, a thing which cannot be done where gas is employed. Speaking generally, gas will produce bright lights and dense shadows, while electricity - a pliant servant in the hands of the artist - can be applied to produce any desired effect.

The principal lighting of any ordinary dwelling-house or mansion could be more effectively and simply carried out by electricity than by gas, while the former is also much more useful for temporary additional lighting.