wer part of the rod upon which the bouquet is mounted, there is
a collar with three branches, by means of which a rotary motion is given
to the flowers through the aid of the hand. The twine used for tying is
thus wound around the stems. When the apparatus is in motion, the twine
unwinds from the spool, and winds around the rod that carries the
flowers, and twists about and holds every stem.

An experienced operator can work very rapidly with this little apparatus,
which has been constructed with much care and ingenuity, and which enters
into a series of special mechanisms that is always of interest to know
about.

The manufacturer was advised to construct his apparatus so that it could
be run by foot power, but, after some trials, it was found that the
addition of a pedal and the mechanism that it necessitates was absolutely
superfluous, the apparatus working very well such as it is.--_La Nature_.

* * * * *

[Continued from SUPPLEMENT, No. 567, page 9057.]

RADII OF CURVATURE GEOMETRICALLY DETERMINED.

By Prof. C.W. MACCORD, Sc.D.

NO. VII.--PATH OF A POINT ON A CONNECTING ROD.

The motion of the connecting rod of a reciprocating steam engine is very
clearly understood from the simple statement that one end travels in a
circle and the other in a right line. From this statement it is also
readily inferred that the path of any point between the centers of the
crank and crosshead pins will be neither circular nor straight, but an
elongated curve. This inference is so far correct, but the very common
impression that the middle point of the rod always describes an ellipse
is quite erroneous. The variation from that curve, while not conspicuous
in all cases, is nevertheless quite sufficient to prevent the use of this
movement for an elliptograph. To this there is, abstractly, one
exception. Referring to Fig. 22 in the preceding article, it will be seen
that if the crank OH and the connecting HE are of equal length, any point
on the latter or on its prolongation, except E, H, and F, will describe
an exact ellipse. But the proportions are here so different from anything
used in steam engines (the stroke being four times the length of the
crank), that this particular arrangement can hardly be considered as what
is ordinarily understood by a "crank and connecting rod movement," such
as is shown in Fig. 23.

The length DE of the curve traced by the point P will evidently be equal