iad._

* * * * *

THE TREATMENT OF GLAUCOMA.

As this disease is so fatal to vision, any remedy that may be
suggested to diminish the frequency of its termination in blindness
cannot fail to be read of with interest. M. Nicati, in the _Revue
generate de clinique et de therapeutique_, has had marked success in
the treatment of glaucoma by drainage of the posterior chamber, either
by sclerotomy or by sclero-iritomy, as the conditions of the
individual case may require.--_N.Y. Med. Jour._

* * * * *

A TWIN SCREW LAUNCH RUN BY A COMPOUND ENGINE.

[Illustration: TWIN SCREW STEAM LAUNCH GEMINI.]

The launch shown in our illustration was built in New Westminster,
British Columbia, Canada. She is 42 ft. keel and 7 ft. beam, and has 4
ft. depth of hold. She has an improved Clarke compound engine, also
shown in an accompanying illustration, with a high pressure piston
four inches in diameter, and a low pressure piston eight inches in
diameter, the stroke being six inches, and the engine driving two
twenty-six inch screws. With 130 pounds of steam, and making 275
revolutions per minute, the launch attains a speed of nine miles per
hour, thus fully demonstrating the adaptability of this engine to the
successful working of twin screws.

[Illustration: THE CLARKE COMPOUND TWIN-SCREW OPERATING ENGINE.]

In the Clarke engine, the exhaust pipe from the high pressure cylinder
leads to the steam chest of the low pressure cylinder, while the
piston in the upper cylinder is secured on a piston rod extending
downward and connected with a piston operating in the lower cylinder,
the exhaust pipe from the latter leading to the outside. On the piston
rod common to both cylinders is secured a crosshead pivotally
connected by two pitmen with opposite crank arms on crank shafts
mounted to turn in suitable bearings on the base, which also supports
a frame carrying the low pressure cylinder, on top of which is a frame
supporting the high pressure cylinder. The valves in the two steam
chests are connected with each other by a valve rod connected at its
lower end in the usual manner with the reversing link, operated from
eccentrics secured on one of the crank shafts.

The crank arms stand at angles to each other, so that the crank shafts
are turned in opposite directions, and the position of the link is
such that it can be readily changed by the reversing lever to
sim