creature are of bulging glass, each one as large as a saucer. His body is an oblong mahogany box, which contains an electric motor, a storage battery, two selenium cells, two relays, and two solenoid magnets. He has no tail to speak of, but in its place is an electric switch. He is controlled by three brass wheels, two in front and one in the rear.

When the motor inside the dog is started, he will do some extraordinary things. If you walk before him carrying a lighted lantern, he will follow you, turning to the right or left as you turn, although you neither touch nor control him in any way that is visible to the spectator. He steers himself briskly after his leader in a way that is positively uncanny. The mystery is solved, however, when it is explained that what guides him is the light from the lantern, which operates upon the strangely sensitive element called selenium. If this light is moved to the left, the left selenium cell receives more of it and thus more stimulation than the right cell, and so allows more current to flow from the storage battery into the left-hand magnet, which then deflects the hind wheel to the left and the dog turns in that direction. For the same reason when one turns to the right, the dog follows. If one wants the dog to go backwards, all that is necessary is to reverse the tail switch. Then, when his master advances on him with the light, he will seemingly become timid and back away in a most surprising manner.

But how can this animal be made useful? Well, so far, of course, the field has not been thoroughly explored; but there are certain household utilitarian purposes to which we might imagine he may be adapted.

Sweeping rugs and carpets constitutes one of the numerous duties of the housewife. This form of drudgery may be done away with by utilizing the electric dog. While vacuum cleaners and patent carpet sweepers have to a certain extent supplanted the old-fashioned but still efficient broom, there is yet a necessary

ate either of them. By a very simple. arrangement, a rotary brush, similar to that used by street railways to sweep the tracks, could be attached to the rear of the dog, together with a pan to catch the refuse from the floor. Then, with a pocket electric light or a small dark lantern in her hand, used as a guiding star, the lady could take her ease in a chair and direct across the carpet the course of this faithful and tireless servant.

In flats or houses not wired for electric lights, the dog may be used to help out the housewife with her sewing. In order to attain this result it would be necessary to have a grooved wheel, a simple accessory that could easily be attached to the mechanism of the apparatus. The latter could then be clamped to a box of convenient height, the sewing machine strap removed from the large wheel and adjusted to the grooved wheel of the dog. A pocket flashlight is installed where the operator could reach it with her foot. it with her foot. By pressing a button, the light could be turned on or off at will, thus starting or stopping the machine as desired.

One of the tables on wheels used for carrying dishes from the dining table into the kitchen might easily be mounted on the back of the dog. He could be made to follow the maid or mistress about as she piled the plates, cups, saucers, etc., on the top and then follow her into the kitchen.

Also, there could be arranged on the top of this table a receptacle for the baby, in which it could be placed for its afternoon nap. Directed by the rays, the whole apparatus would traverse the room and a mechanism could automatically reverse an electric switch after the vehicle had gone a certain distance, and compel it to retrace its path. In the course of time, and with proper development, this selenium dog with his accessories might be utilized in the moving of heavy furniture, such as pianos, tables, refrigerators, and trunks, and thus assist materially during the trying days of

bell proper, connected with dry batteries, wherever it may be deemed advisable to place the alarm bell-if in the home, in the bedroom of the head of the house; if in the office, the wire may lead to the nearest police station. When the gentlemanly burglar enters the room and flashes his electric pocket light, its rays will strike the selenium cell and the gong will ring. But this is not all that may be accomplished, if a little mechanical ingenuity is brought into play. A revolver and a camera might be added to the equipment to complete the discomfiture of the burglar. The revolver, aimed in his direction, would either cripple him or give him a good fright, while at the same time a flashlight would enable the camera to take a photograph of him.

By mounting a revolving drum or capstan on the dog, and equipping the head of each flight of stairs with a hook, the dog could be made to pull himself from floor to floor, in order to fulfill his household duties anywhere in the structure. Inasmuch as he would be a heavy dog, this might be necessary; but of course, he could be made to carry loads on his

THE LUXURY OF SWEEPING FLOORS The housewife can make the electric dog do the work.

By mounting a row of three auxiliary eyes, each with a different colored glass in front of it, even greater results would be secured. Turning on a red light would actuate only the red cell, inasmuch as the light would not pierce the blue and yellow filters. If some place is expected to burst forth into flame-as, for instance, a rubbish heap-the dog might be put on watch, ready to send an alarm if red and yellow light from an incipient fire fall upon his eyes. For ordinary household use, a lantern equipped with white, red, yellow, and blue eyes could give a variety of signals that would cause the dog to perform a multitude of tasks.

A refinement that would immensely increase his usefulness would result if his eyes could be kept turned toward the light, no matter where he should be in the room. With such a device, and a mirror opposite the door, the dog could even be sent out of the room on errands. Truly, the possibilities for the electric dog are endless.