form of fine spray to a distance of 20 ft. at each side. The drops are
received in the tank or pond, and in their rapid passage through the
air are sufficiently cooled to be again injected into the condenser.

The illustration shows a cooler having a basket three feet in
diameter, revolving at 300 revolutions per minute, and discharging
into a tank 40 ft. square. It requires 3 to 4 indicated horse-power to
drive it, and will cool 300 gallons per minute. The following decrease
of temperature has been observed in actual practice: Water entering at
95 deg. fell 20 deg. in temperature; water entering at 100 deg. to 110
deg. fell 25 deg.; and water entering at 110 deg. to 120 deg. fell 30
deg. The machine with which these trials were made was so placed that
the top of the basket was four ft. from the surface of the water in
the pond. With a greater elevation, as shown in the engraving, better
results can be obtained.

[Illustration: IMPROVED WATER COOLING APPARATUS.]

The advantages claimed for the cooler are that by its means the
temperature of the injection water can be reduced, the cost and size
of cooling ponds can be diminished, and condensing engines can be
employed where hitherto they have not been possible. The apparatus has
been for two years in operation at several large factories, and there
is every reason to believe that its use will extend, as it supplies a
real want in a very simple and ingenious manner. Messrs. Duncan
Brothers, of Dundee and 32 Queen Victoria Street, E.C., are the
manufacturers.

* * * * *

CORRUGATED DISK PULLEYS.

This is a pulley recently introduced by Messrs. J. and E. Hall, of
Dartford Eng. With the exception of the boss, which is cast, it is
composed entirely of steel or sheet iron. In place of the usual arms a
continuous web of corrugated sheet metal connects the boss to the rim;
this web is attached to the boss by means of Spence's metal. Inside
the rim, which is flanged inward, a double hoop iron ring is fixed for
strengthening purposes. The advantageous disposition of metal obtained
by means of the corrugated web enables the pulley to be made of a
given strength with less weight of material, and from this cause and
also on account of being accurately balanced these pulleys are well
adapted for high speeds.

[Illustration]

* * * * *

[KANSAS CITY REVIEW.]

EARLY HISTORY OF THE TELEGRAPH.

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