diment runs into the
pulp-reservoir, o. The pump, l, forces the milky liquid from the
reservoir, m, to the settling back, while the pulp is forced by a pump,
u, from the receptacle, o, into a large pulp-reservoir.

The water necessary for the manufacture is forced by the pump, a, into
the reservoir, W, from whence it flows, through the pipes, r, into the
different machines. All the apparatus are set in motion by two
shaftings, q. The principal shaft makes two hundred revolutions per
minute, but the velocity of that of the pumps is but fifty
revolutions.--_Polytech. Journ., and Bull. Musee de l'Indust_.

* * * * *

A SIMPLE APPARATUS FOR DESCRIBING ELLIPSES.

By Prof. E.J. HALLOCK.

A very simple apparatus for describing an oval or ellipse may be
constructed by any apprentice or school boy as follows: Procure a
straight piece of wood about 1/4 inch wide by 1/8 inch thick and 13 inches
long. Beginning 1/2 inch from the end, bore a row of small holes only
large enough for a darning needle to pass through and half an inch
apart. Mark the first one (at A) 0, the third 1, the fifth 2, and so on
to 12, so that the numbers represent the distance from O in inches. A
small slit may be made in the end of the ruler or strip of wood near A,
but a better plan is to attach a small clip on one side.

[Illustration: ELLIPSE INSTRUMENT.]

Next procure a strong piece of linen thread about four feet long; pass
it through the eye of a coarse needle, wax and twist it until it forms a
single cord. Pass the needle _upward_ through the hole marked 0, and tie
a knot in the end of the thread to prevent its slipping through. The
apparatus is now ready for immediate use. It only remains to set it to
the size of the oval desired.

Suppose it is required to describe an ellipse the longer diameter of
which is 8 inches, and the distance between the foci 5 inches. Insert a
pin or small tack loosely in the hole between 6 and 7, which is distant
6-1/2 inches from O. Pass the needle through hole 5, allowing the thread
to pass around the tack or pin; draw it tightly and fasten it in the
slit or clip at the end. Lay the apparatus on a smooth sheet of paper,
place the point of a pencil at E, and keeping the string tight pass it
around and describe the curve, just in the same manner as when the two
ends of the string are fastened to the paper at the foci. The chief
advantage claimed over the usual method is that