to the fly wheel, and the motor starts. The feeding is afterward done
with coke.

The parts that transmit motion operate under conditions analogous to
those under which the same parts of a steam engine do. The air pump
sucks and forces nothing but cold air, and nothing but cold air passes
through the distributing slide valve. The pump and valve are therefore
rendered very durable. The piston and cylinder, at the points where
friction exists, are at a temperature of 60 or 80 degrees. These
surfaces are protected against hot gas charged with dust.

The hot gas, which escapes from the cylinder through a valve, has
previously been cooled by contact with the sides of the cylinder and
by expansion. The eduction valve just mentioned works about like that
of a steam engine, and it is only necessary to polish it now and then
in order to keep it in good condition.--_Annales Industrielles._

* * * * *




YOUR FUTURE PROBLEMS.[1]

[Footnote 1: An address to the graduating class, Stevens
Institute, Hoboken, N.J., 1887.]

By CHARLES E. EMERY.