1st. That every motion of the machine should do some useful work.
Hitherto box or barrel mixers have gone on the principle of
throwing the material about indiscriminately, expecting that
somehow or other it would get mixed.

2d. That the sticking of the material anywhere within the mixer
should be obviated.

3d. That an easy discharge should be obtained.

4th. That the water should be introduced while the mixer
revolves.

With these desiderata in view, a box was designed which in half a turn
gathers the material, then spreads it, and throws it from one side to
the other at the same time that water is being introduced through a
hollow trunnion.

It is also so constructed that all the sides slope steeply toward the
discharge, and there is not a rectangular or acute angle within the
box. A machine has now been worked steadily for several weeks, putting
in the concrete in the foundations of the new Jackson Street bridge in
this city, by General Fitz-Simons. The result exceeds expectations.
The concrete is perfectly mixed, the discharge is simple, complete and
effective, and at the same time the cost of labor in mixing and
placing in position is lessened by 50 per cent. as compared with any
known to have been put in under similar circumstances.--_Jour.
Association of Engineering Societies._

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