nozzle.
When the nozzle is in its highest position the needle tip is withdrawn;
as the nozzle sinks the needle protrudes, gradually decreasing the
discharge area of the nozzle.

Pelton wheels are designed to run at all speeds and to use water of any
pressure. At Manitou, Colorado, is an installation of three wheels
operated by water which leaves the nozzle at the enormous pressure of
935 lbs. per square inch. It is interesting to note that jets of very
high-pressure water offer astonishing resistance to any attempt to
deflect their course. A three-inch jet of 500-lb. water cannot be cut
through by a blow from a crowbar.

In order to get sufficient pressure for working hydraulic machinery in
mines, factories, etc., water is often led for many miles in flumes, or
artificial channels, along the sides of valleys from the source of
supply to the point at which it is to be used. By the time that point is
reached the difference between the gradients of the flume and of the
valley bottom has produced a difference in height of some hundreds of
feet.

[Illustration: FIG. 190.--The Laxey water-wheel, Isle of Man. In the
top right-hand corner is a Pelton wheel of proportionate size required
to do the same amount of work with the same consumption of water at the
same pressure.]

The full-page illustration on p. 380 affords a striking testimony to
the wonderful progress made in engineering practice during the last
fifty years. The huge water-wheel which forms the bulk of the picture is
that at Laxey, in the Isle of Man. It is 72-1/2 feet in diameter, and is
supposed to develop 150 horse-power, which is transmitted several
hundreds of feet by means of wooden rods supported at regular intervals.
The power thus transmitted operates a system of pumps in a lead mine,
raising 250 gallons of water per minute, to an elevation of 1,200 feet.
The driving water is brought some distance to the wheel in an
underground conduit, and is carried up the masonry tower by pressure,
flowing over the top into the buckets on the circumference of the wheel.

The little cut in the upper corner represents a Pelton wheel drawn on
the same scale, which, given an equal supply of water at the same
pressure, would develop the same power as the Laxey monster. By the side
of the giant the other appears a mere toy.

THE CREAM SEPARATOR.

In 1864 Denmark went to war with Germany, and emerged from the short
struggle shorn of the provinces of Lauenburg, Holst