cases may incline
upwards: the wheel being thus prepared, tie in each groove a
four-ounce case filled with a grey charge; then carry a leader from
the tail of one case to the mouth of the other.

Globes for these wheels are made of two in hoops, with their edges
outwards, fixed one within the other, at right angles. The diameter of
these hoops must be rather less than that of the wheel. Having made
the globe, drive in the centre of the wheel an iron spindle which must
stand perpendicular, and its length be four or six inches more than
the diameter of the globe.

The spindle serves for an axis, on which is fixed the globe, which
must stand four or six inches from the wheel; round one side of each
hoop must be soldered little bits of tin, two inches and a half
distance from each other; which pieces must be two inches in length
each, and only fastened at one end, the other ends being left loose,
to turn round the small port-fires, and hold them on: these port-fires
must be made of such a length as will last out the cases on the wheel.
There need not be any port-fires at the bottom of the globe within
four inches of the spindle, as they would have no effect but to burn
the wheel: all the port-fires must be placed perpendicularly from the
centre of the globe, with their mouths outwards, and must be clothed
with leaders, so as all to take fire with the second case of the
wheel; and the cases must burn two at a time, one opposite the other.
When two cases of a wheel begin together, two will end together;
therefore the two opposite end cases must have their ends pinched and
secured from fire. The method of firing such wheels is, by carrying a
leader from the mouth of one of the first cases to that of the other;
and the leader being burnt through the middle, will give fire to both
at the same time.

_Odoriferous Water-Balloons._

They are made in the same manner as air-balloons, but very thin of
paper, and in diameter one inch and three-fourths, with a vent of half
an inch diameter. The shells being made, and quite dry, fill them with
any of the following compositions, which must be rammed in tight:
these balloons must be fired at the vent, and put into a bowl of
water. Odoriferous works are generally fired in rooms.

_Composition I._ Saltpetre two ounces, flour of sulphur one ounce,
camphor half an ounce, yellow amber half an ounce, charcoal-dust
three-fourths of an ounce, salt of Benzoin half an ounce, all powdered
ve