of calico, and divide its circumference into ten or twelve equal parts. At
each point of division we attach a piece of fine hempen cord about three
feet in length, and connect these cords with each other, as well as with
the suspension chain, by ligatures that are protected against the fire by
means of balls of sized paper.

In rockets designed to receive these parachutes, a small cavity is reserved
at the extremity of the cartridge for the reception of 225 grains of
powder. To fill the pot, the chain, _d_, is rolled spirally around the box,
_c_, and the latter is covered with the parachute, _e_, which has been
folded in plaits, and then folded lengthwise alternately in one direction
and the other.

The _parachute port-fire_ consists of a cardboard tube of from quarter to
half an inch in diameter, and from four to five inches in length, closed at
one extremity and filled with star paste. This is connected by a brass wire
with a cotton parachute eight inches in diameter. A rocket pot is capable
of holding twenty of these port-fires.

Parachute fires and port-fires are used to advantage in the operation of
signaling.--_La Nature_.

* * * * *




IMPROVEMENT IN LAYING OUT FRAMES OF VESSELS--THE FRAME TRACER.

By GUSTAVE SONNENBURG.