lamps in the Alhambra Courts were lit by the current from these accumulators; and the intensity of the light was easily graduated by switching in or out a group of cells. The current from them is quite steady,

and the lamps are found to stand a higher current and give a brighter light than they could if fed by the current from a dynamo direct. This is owing to the fact that the currents from even the best dynamos are vibratory and shake the filaments.

Some 70 or 80 per cent. of the energy of the current from the generator can thus be reclaimed at any future time. No doubt this is a considerable loss, but when we remember that the variable power of winds, waves, and waterfalls—which is now largely wasted-could in this way be utilised, the practical gain is seen to be considerable. Moreover, these accumulators are certain to be improved in course of time, and there is no doubt but they would be very useful at central stations or in houses for yielding a supply of current which would serve for household uses whilst the generators were idle. They also serve to regulate the electric light, as they render the currents from the generator more continuous, and less liable to break the carbon filaments in an incandescent lamp.

Indeed, it is not unlikely that these accumulators will be specially used for rendering the intermittent current absolutely continuous. The arrangement is shown in Fig. 75, where D is the dynamo generating the current, which is led away to the accumulators AAA by conducting wires w w. The lamp circuits L L, instead of being connected in the direct circuit of the wires w w, are joined across the poles of the accumulators, and draw a steady current from it, all the while the dynamo continues to charge them with more or less intermittent currents. Should the dynamo stop working from any cause, the lamps will not go out, because of the charge remaining in the accumulators.

Secondary batteries charged with electricity could of course be delivered to consumers like other goods, and returned empty to be charged again; but this

way of distributing the current does not seem a profitable one, and will only be resorted to in special cases, where a temporary supply is wanted. A surgeon or an electrician may sometimes require a portable charge for medical or for testing purposes, which an accumulator

will enable him to have. In the actual cautery a fine platinum wire heated to incandescence is now employed to sever the flesh, and in examinations of the mouth and other parts of the body difficult of access, a tiny electric light is sometimes used. Such is the polyscope of M. Trouvé, which comprises a case containing either

a voltaic or a secondary battery, supplying current to a small platinum wick or electropyre mounted in the hollow shell of a tiny silvered reflector. The current is leton by a press button and its strength can be graduated at will by help of a current indicator.

The tiny light can be directed upon a particular spot by means of the handle, and as it gives off little heat and no fumes it does not inconvenience the patient. Glass bulbs illuminated in this way have been inserted into the stomach of fishes and other semi-transparent animals to exhibit their internal structure; and an Austrian physiologist has designed an apparatus of the kind whereby the internal coatings of the human stomach can be inspected by inserting a little incandescent bulb and reflecting an image of the coating from a small mirror up a tube and out at the mouth.

The general advantages of the electric light over gas are many and various. In gas we are burning a foul distillation from coal, and consuming as well as polluting the air we breathe. Our supply of coal is exhaustible, but our supply of electricity is inexhaustible. In electricity we have a pure ethereal source of light destined to be the illuminant of the future. The arc lamps, it is true, while they yield a brilliant focus, give off very small traces of deleterious vapours, but arc lights are to be used out of doors, in streets, squares, and as head-lights on ships and locomotives, or as beacon-lights on headlands. The domestic light is the incandescent lamp, and in this we have a brilliant and mellow source which neither burns, nor taints, nor unduly heats the air. So like sunshine is it that it shows the most delicate colours in a very near approach

to their daylight shades; and as wires can be led to places where oil or gas-pipes cannot reach, it is eminently adapted for decorative purposes. The pictures and hangings of a room are seen to advantage by it, and it can neither tarnish gilding nor blacken paint. Moreover, when it can be supplied at large, the cost will be even less than that of gas.