will alone effect a very great saving, as we are informed that on the Lyons Railway, which is 800 kilometers long, the cost of oil and grease exceeds L400,000 per annum.  As Sir Edward Watkin recently explained, all the great railway companies have long tried to find a substitute for wheels, and this railway appears to offer a solution of that problem.  Mons. Barre thinks that a speed of 200 kilometers (or 120 miles) per hour may be easily and safely attained.

[Illustration:  FIG. 7.]

[Illustration:  FIG. 8.]

Of course, as there is no heavy locomotive, and as the traction does not depend upon pressure on the rail, the road may be made comparatively light.  The force required to move a wagon along the road is very small, Mons. Barre stating, as the result of his experiments, that an effort amounting to less than half a kilogramme is sufficient to move one ton when suspended on a film of water with his improved shoes.  It is recommended that the stations be placed at the summit of a double incline, so that on going up one side of the incline the motion of the train may be arrested, and on starting it may be assisted.  No brakes are required, as the friction of the shoe against the rail, when the water under pressure is not being forced through, is found to be quite sufficient to bring the train to a standstill in a very short distance.  The same water is run into troughs by the side of the line, and can be used over and over again indefinitely, and in the case of long journeys, the water required for the tender could be taken up while the train is running.  The principal advantages claimed for the railway are:  The absence of vibration and of side rolling motion; the pleasure of traveling is comparable to that of sleighing over a surface of ice, there is no noise, and what is important in town railways, no smoke; no dust is caused by the motion of the train during the journey.  It is not easy for the carriages to be thrown from the rails, since any body getting on the rail is easily thrown off by the shoe, and will not be liable to get underneath, as is the case with wheels; the train can be stopped almost instantly, very smoothly, and without shock.  Very high speed can be attained; with water at a pressure of 10 kilogrammes, a speed of 140 kilometers per hour can be attained; great facility in climbing up inclines and turning round the curves; as fixed engines are employed to obtain the pressure, there is great economy in the use of coal and construction of boilers, and there is a total absence of the expense of lubrication.  It is, however, difficult to see how the railway is to work during a long and severe frost.  We hope to give further illustrations at an early date of this remarkable invention.—­Industries.

* * * * *

QUARTZ FIBERS.[1]

    [Footnote 1:  Lecture delivered at the Royal Institution, on
    Friday, June 14, by Mr. C. V. Boys, F.R.S.—­Nature.]