cle

[Illustration: Pattern for Cutting the Segments]

into 10 equal parts and also divide one-half of the line AB in 10
equal parts. Perpendicular lines are drawn parallel with the line
CD intersecting the division points made on the one-half line AB.
Horizontal and parallel lines with AB are drawn intersecting the
division points made on the one-quarter circle and intersecting
the perpendicular line drawn parallel with CD. A line is now drawn
from B to E and from E to F, and so on, until all the intersecting
lines are touched and the point C is reached. This will form the
proper curve to cut the pattern. The paper is now folded on the
line AB and then on the line CD, keeping the marked part on the
outside. The pattern is now cut, cutting all four quarters at the
same time, on the curved line from B to C. When the paper is
unfolded you will have a pattern as shown in Fig. 2. This pattern
is used to mark the cloth, and after marked is cut the same shape
and size.

The cloth segments are sewed together, using a fine needle and No.
70 thread, making a double seam as shown in Fig. 3. When all seams
are completed you will have a bag the shape shown in Fig. 4. A
small portion of one end or a seam must be left open for
inflating. A small tube made from the cloth and sewed into one end
will make a better place for inflating and to tie up tightly.

It is now necessary to varnish the bag in order to make it retain
the gas. Procure 1 gal. of the very best heavy body, boiled
linseed oil and immerse the bag in it. The surplus oil is squeezed
out by running the bag through an ordinary clothes wringer several
times. The bag is now placed in the sun for a thorough drying. Put
the remaining oil in a kettle with 1/8 lb. of beeswax and boil
well together. This solution is afterward diluted with turpentine
so it will work well. When the bag is dry apply this mixture by
rubbing it on the bag with a piece of flannel. Repeat this
operation four times,

[Illustration: Sewing Segments Together]

being sure of a thorough drying in the sun each time. For indoor
coating and drying use a small amount of plumbic oxide. This will
dry rapidly in the shade and will not make the oil hard.

Fill the bag with air by using a pair of bellows and leave it over
night. This test will show if the bag is airtight. If it is not
tight then the bag needs another rubbing. The next operation is to
fill the bag with gas.

Hydrogen gas is made from iron an