Gnats are fascinated by a powerful electric lamp, and dance about it as they do in a beam of evening sunshine. Light has an attraction for many animals besides insects. Flying-fish spring out of the sea when sailors hang a lantern by the ship’s side; and in California now it is the custom to submerge a cluster of Edison lamps from the bows of a boat with a net expanded below. When the fish gather round the light the net is closed on them, and after being hauled out of the water they are put into water-tanks, and sent alive on special cars by overland rail to New York and the Eastern States. The French chasseur also makes a bag sometimes by employing an electric light to attract his feathered game; pigeons especially being lured by it.
Owing to its power, the arc-light is very well suited for signalling purposes; and hence it is now used with the heliograph to signal the approach of cyclones between the British island of Mauritius and Reunion in the Indian Ocean. It has also been proposed to signal by transparent balloons lit by incandescence lamps. The balloon is raised to a good height by a rope which also carries the wires conveying the current to the lamps; and flashes according to an understood code of signals are made by working a key to interrupt the current, as in the act of telegraphing.
Diving operations under the sea are greatly facilitated by the electric light; and a trial was recently made of a powerful lamp at Marseilles in lighting up the hull of a sunken ship. The amber hunters of the Baltic are also using the light for seeking the fossil gum on the sea-bed, instead of waiting until the waves cast it on the shore. Sea-water is remarkably clear, and the rocks of the seashore are often beautifully covered with weeds and shells. It is no wonder, then, that a submarine balloon has been devised by one Signor Toselli at Nice, for going under water to examine them. This observatory holds eight people, and has a glass bottom and an electric light for illuminating the sea-caves.
The electric light is not free from danger; but, from not being explosive, it is far from being as fatal in its effects as gas. There have been several deaths from electric shock caused by the very powerful currents of the Brush and Jablochkoff machines. For instance, a man was killed instantly on board the late Czar’s yacht Livadia when crossing the Bay of Biscay. He had accidentally grasped the bare connections of one of the electric lamps and received the current through his breast. Others have been killed by touching bare wires conveying the current; a man in Kansas City, United States, met his death quite recently in repairing some electric light wires without knowing that the current flowed in them. Carelessness of some kind was the source of these misfortunes; but the use of such very deadly currents is to be deprecated. When the electromotive force of an electric current exceeds five hundred volts it becomes dangerous, and hence it is that the Board of Trade prohibits the use of more powerful currents for general lighting. The use of overhead wires, sometimes uninsulated and never wholly insulated, such as obtains in some parts of the United States, ought also to be eschewed, and underground cables, safe out of harm’s way, employed instead. With cables buried in the earth, we should not have a repetition of the curious incident which recently happened at the Luray Cavern in Virginia, where lightning ran into the cave along the electric light conductors and destroyed some of the finest stalactites.
The plan of having tall masts with a cluster of very powerful lights reflected from the height by mirrors is a very good one, since it obviates the distribution of wires and lamps. By imitating the sun, in this way a Californian town is entirely lighted from one or two masts; and it is satisfactory to know that the system is being tried at South Kensington.
The dynamos of electric machines have been known to explode, or rather burst from the centrifugal force due to the rapid revolution of the armature. An accident of this kind recently caused great alarm in a New York theatre. Sparks from the red-hot carbons of arc-lamps, or between wire and wire of the conductors, have also led to many small fires; but none of any great consequence. A spark is so feeble a source of heat that, unlike the spilling of an oil-lamp, it does not produce a powerful fire, provided the materials it falls among are not highly inflammable. On the whole, the danger of fire with electric lighting, especially incandescence lighting, has probably been exaggerated. The incandescence lamp itself is very safe, since if one be enveloped in light dry muslin and broken, the muslin is not burnt. In fact, the rush of air caused by the broken vacuum entirely dissipates the red-hot filament.
From its injurious aspects we turn now to its beneficial qualities. The arc-light by its brilliance is not good for the eyesight when looked at direct, but there is probably nothing harmful in the light itself, unless it should be the excess of violet rays. It is a cool light; and hot lights, by drying the natural humours of the eye, are the most prejudicial to the sight. The incandescence light which is free from excess of violet rays is also a cool light; and as it neither pollutes nor burns the air of a chamber, it is the best light for a student. Small reading-lamps, fitted with movable arms carrying incandescent bulbs, are now manufactured for this purpose. Even with the incandescence lamp, however, it is advisable not to look at the brilliant filament.
Surgeons and dentists find these little incandescence lamps of great service in examining the teeth and mouth. Some are made no larger than a pea. Others are fitted into silver probes (cooled by circulating water) for insertion into the stomach to illuminate its coats, or enable a physician to diagnose other internal organs. Dr Payne, of Newcastle-on-Tyne, recently made an examination of the liver by inserting one of these endoscopes into it through an incision made in the abdomen. M. Trouvé has also fitted a small lamp to a belt which goes round the physician’s forehead, thereby enabling him to direct the light to where he is looking. Another experimenter has so applied the light that he has been able to photograph the vocal chords while in the act of singing; and a third has illuminated the whole interior of a living fish, so that all the main physiological operations could be witnessed by a class of students. Such services as these could not be rendered by any other known illuminator.
HUSH-MONEY.
Out of the countless variety of evil-doers who thrive upon the misfortunes of their fellow-creatures, and are enabled to gain a means of livelihood by the folly and timidity of their dupes, one class above all others seem to conduct their depredations with much success, on account of the defenceless position of the unhappy individuals upon whom they prey. We allude to those who make it their business to levy what is termed ‘hush-money.’