recently announced theory for over thirty years. During all this time he has been making continuous experiments. The working model which he designed was completed more than two years ago. Now, with full confidence in his discovery, he at last proclaims it to the world. Financially, he has been assisted to some extent by the British and Indian governments. It was in compliance with their request that for some two years he has kept silent. Now that the government of In

dia purposes to make an early experiment with his invention in the rougher sections of that country, the secret is out.

When the members of the Royal Society of London were invited to the private grounds of the inventor, to examine into his work, they saw things that made

A GYROSCOPIC TOP, THE SIMPLEST FORM OF GYROSCOPE.

them marvel. First, they were shown a model of the new locomotive, for which its inventor had hinted incredible possibilities. The oddity of its construction was at once apparent. It consists of a long, shallow body upon a pair of twowheeled motor trucks. These wheels,

THE MONO-RAIL ROUNDING A CURVE.

however, were not placed in double row, but one behind the other, like those of a bicycle. Two electric motors were provided to turn the four wheels, all of which acted as drivers. They further saw a closed compartment in the forward end of the car, and in the rear of this the strange mechanical device that made this unusual build possible-the gyroscope. What is a gyroscope? It consists essentially of a disk revolving on pivots within a ring, having on the line of prolongation of its axis, on one side, a bar or spur with a smooth notch beneath to receive the hard, smooth point of an upright support. Thus placed, when the disk is not turning, the whole falls, of course, like any heavy body unsupported. If rotated rapidly by unwinding a string, set on the support, while the opposite side of the ring is upheld no peculiar movement then occurs; but if while the disk is rapidly turning, the bar being on the support, the opposite side be set free, the whole, instead of falling, as would be expected, commences a steady revolution in a horizontal circuit. about the point of support, moving more rapidly as the primary rotation is expended, and sinking, at first imperceptibly, then more rapidly, until in from one to three minutes it comes to rest. Such is the ordinary gyroscope.

From a gyroscopic top, which can be bought at almost any toy shop, the prin

vacuum is to cause the gyroscopic wheels to revolve for some time after the current is cut off. He also told them that the gyroscopes rotate in opposite directions at the speed of 7,500 revolutions a minute. The weight of these gyroscopes is five per cent that of the weight of the whole machine. When the locomotive was set in operation another surprise developed for the investigators. Away flew the car on its single rail. It shot up steep grades, took sharp curves, and ran along a suspended wire cable.

Gaso

scopic, or mono-rail, locomotive. line will be the motive power. The gyroscope planned will make from 2,000 to 3,000 revolutions per minute, which the inventor claims is sufficient.

The railway coaches of the present are limited in size by the necessity of having a double rail track system. The mono-rail is not thus handicapped. If it is shown that the device is practical on as large a scale as that of the ordinary coach, there is nothing to prevent one's traveling in a vehicle as well-equipped as a

first-class hotel. The carriages may be fitted with rooms for every purpose, such as for smoking, dining, reading, writing. Even promenade and music rooms to relieve the tedium of travel are not too much to expect. And all this on a train that will travel without a jar at a speed of over one hundred miles an hour. For the peculiar balancing qualities of the gyroscope tend to obviate side oscillation, and the absence of a parallel track, which of necessity can never be quite parallel, does away completely with the bumps and jars produced by one rail being a trifle higher than its fellow, or a fraction of an inch out of alignment. It is owing to this lack of lateral oscillation and the remarkable reduction of friction due to the use of the single rail and absence of flange-pressure on curves that such high speed can be, attained.

The tremendous economy of a single rail and a wide car are easily apparent. In the first place the cost of steel is cut in two. The sleepers also only require to be one-half their present length, or less. Moreover, the present massive bridge may be dispensed with. For temporary work, a single wire hawser

stretched across a ravine or river is all that is necessary. It is claimed that the swaying of this hawser cannot disturb the balance of the cars, and that the strongest winds will fail to blow them off. For permanent work a single row of piles with a rail on top will suffice, or a single girder carrying the rail may be conveniently used. With reduced friction in the mono-rail system, the cost for fuel will be less. Another advantage in this respect is that either steam, petrol, oil, gas, or electricity may be used, as best suits local conditions. The danger of derailment at high speeds is also obviated. When these various things are considered, the wonderful advantages of the mono-rail system become evident.

There is another side to all this, however. Mechanical effects that work perfectly on a small scale may fail utterly when put to practical use. The inventor states that the weight of the gyroscope is but five per cent of the total weight of the car. Five per cent of sixty tons, the weight of an average coach at the present time, would be three tons. A fly-wheel of that weight, going at so great a speed, would be subjected to a

NE of the embarrassing problems that have been successfully solved by the ingenious Western miner, is that of taking care of the mountains of débris, boulders and gravel that are washed down in the course of surface digging in the quest for gold. After a half-century of constant work, the diggings of many of the placer mines have narrowed down, and now confine themselves to the more remote slopes and gulches, which, a few years ago could not have been worked by the methods. then known. In former days every hydraulic placer mine had to have good "dumping grounds;" which meant that there must be a sheer fall or drop of from twenty-five to two hundred feet from the end of the sluices. Unless there was such fall, the sluices would soon be choked up by the accumulation of boulders and débris. But now diggings are being profitably worked that have practically no natural dump, an artificial dumping ground being created through the assistance of the hydraulic elevator.

The tubular type of tailings elevator is now being used and introduced on all Western

placer mines that are confronted with the "dump problem." This elevator is easily constructed by any mine foreman or superintendent. Primarily it consists of a section or more of standard hydraulic steel piping, set at an incline of sixty or seventy degrees, over the end of the bedrock race of the diggings. At the base of the pipe a monitor is set, with