d sulphuric acid. The amounts
necessary for a 10-ft. balloon are 125 lb. of iron borings and 125
lb. of sulphuric acid. 1 lb. of iron, 1 lb. of sulphuric acid and
4 lb. of water will make 4 cu. ft. of gas in one hour. Secure two
empty barrels of about 52 gal. capacity and connect them, as shown
in Fig. 5, with 3/4-in. pipe. In the barrel, A, place the iron
borings and fill one-half full of clear water. Fill the other
barrel, B, with water 2 in. above the level of the water in barrel
A. This is to give a water pressure head against foaming when the
generator is in action. About 15 lb. of lime should be well mixed
with the water in the barrel B. All

[Illustration: FIG. 5; The Hydrogen Generator]

joints must be sealed with plaster of Paris. Pour in one-half of
the acid into the barrel, A, with the iron borings. The barrels
are kept tight while the generation is going on with the exception
of the outlet, C, to the bag. When the action is stopped in the
generator barrel, A, let the solution run out and fill again as
before with water and acid on the iron borings. The outlet, C,
should be always connected with the bag while the generator is in
action. The 3/4-in. pipe extending down into the cooling tank, B,
should not enter into the water over 8 in. When filled with gas
the balloon is ready for a flight at the will of the operator.

** How to Clean a Clock [119]

It is very simple to clean a clock, which may sound rather absurd.
For an amateur it is not always necessary to take the clock to
pieces. With a little care and patience and using some benzine, a
clean white rag, a sable brush and some oil a clock can be cleaned
and put into first-class running order. The benzine should be
clean and free from oil. You can test benzine by putting a little
on the back of the hand; if it is good it will dry off, leaving
the hand quite clean, but if any grease remains on the hand, it is
not fit to use.

The oil should be of the very best that can be procured. Vegetable
oils should never be used. Clock oil can be procured from your
druggist or jeweler.

All loose dirt should be removed from the works by blowing with
bellows, or a fan, or dusting with a dry brush; in the latter case
great care should be exercised not to injure any of the parts. Dip
the brush in the benzine and clean the spindles and spindle holes,
and the teeth of the escapement wheel. After washing a part, wipe
the brush on the rag and rinse in the benzine