45. Now, the first form of wheel of which I shall speak is that usually
known by the name of the “_Common Single Triangle Wheel_.” Its
manufacture is very simple. Provide a piece of light beech wood, of
hexagonal form, each of whose sides is two inches in length (fig. 59).
[Illustration:
Fig. 59.
]
[Illustration:
Fig. 60.
]
[Illustration:
Fig. 61.
]
This hexagonal piece of wood may be about half-an-inch thick. Then bore
through its true centre a hole about three-quarters of an inch in
diameter, into which glue firmly a piece of wood turned or cut to the
shape given in the drawing (fig. 60). Through this piece bore, _in its
exact centre_, a hole about a quarter of an inch in diameter, and, when
bored, burn it through with a piece of quarter inch iron rod, red hot.
This is the hole through which the spindle is to pass which is to form
the axle of the wheel. When the operation is finished, the side view of
your framework will be like the accompanying sketch (fig. 61). The
object of this centre is twofold; first, to obtain a greater steadiness
in the motion of the wheel, by increasing the length of the hole through
which the spindle runs; and, secondly, to keep the wheel, during its
revolutions, from touching against the post into which the spindle is
driven—_a precaution never to be forgotten in the case of vertical
wheels of all descriptions_.
I must next suppose you to have three cases of the 1-oz. size ready
filled and primed and papered. Before fastening these on your framework
_take especial care that the one which is to burn last has its end
stopped up with some incombustible material_. The best plan is to ram
some powdered clay upon the composition before removing the case from
the nipple, in the same manner as recommended for the ends of rockets.
If some precaution of this kind be not taken, the fire issuing from the
mouth of the first of your three cases will be communicated to the tail
of the third, and thus bring your wheel to a most inglorious end.
Having, then, taken this precaution, proceed to tie on your cases to the
edge of your wooden framework. This is easily done if you bore two
holes, through which your string can pass, close to each of those sides
of the frame on which the cases are to lie. A reference to the sketch of
the framework (fig. 59) will show you where these holes should be made.
[Illustration:
Fig. 62.
]
In tying on your cases, be quite sure that the mouths or choked ends of
them lie all in the same direction, in such a manner that the tail of
the first case reaches almost to the mouth of the second; the tail of
the second to the mouth of the third; the tail of the third to the mouth
of the first. When you have secured them firmly in their places with
string, you can then proceed to connect them with quick-match—or
_clothe_ them, as it is called—so that when one case is burned out it
will communicate its fire to the mouth of the next, and so on till they
are all consumed.
In cutting your quick-match, bear in mind that about an inch of the
black match itself must project uncovered beyond each end of the paper
tubes in which it burns. This is to insure its taking and communicating
its fire. In the annexed sketch (fig. 63) you will see represented a
piece of quick-match as it should be cut for connecting cases. At fig.
64 is represented a wheel-case, such as is to burn second in your single
triangle, and has a piece of quick-match, like fig. 63, at each of its
ends, to connect it with the first and third case on the wheel. You will
observe that the newspaper which projected beyond the ends of the case
is simply tied in tightly round the quick-match. You will, after a few
trials, be able to get through this “clothing” operation very easily,
and with no unnecessary wasting of quick-match.
[Illustration:
Fig. 63.
]
[Illustration:
Fig. 64.
]
The mouth of your first case may either be finished off with
touch-paper, or may have a short piece of quick-match put into it, to be
lighted with a portfire.
Your wheel is now completed and ready for firing. But I may as well
suggest here that its beauty and effectiveness will be very much
enhanced if the three cases on it be filled with different compositions.
For instance, fill the case _which is to burn first_ with composition
No. 2; that which is to burn second with No. 4; and the third case with
No. 1. This plan of varying the compositions, or any other that suggests
itself, may be adopted in the case of _all_ wheels. It is necessary,
however, that you should be well acquainted with the character of each
composition, in order that you may be able to produce the exact effect
that you require at the right time.
Composition No. 1 gives only brilliant sparks, and must be prepared as
shortly as possible before use.
Composition No. 2 will give a whitish circle of fire fringed with red
sparks.
Composition No. 3 produces less white flame and more sparks than No. 2.
No. 4 is a sparkling composition; by far the best for general use, in my
opinion.
No. 5 gives reddish sparks, which fly off in very straight lines from
the wheel, and form rays, as it were.
No. 6 gives rays, brilliant sparks, and a centre circle of white fire.
No. 7 gives a moderately good centre, with drossy red sparks of a
peculiar shape.
Those compositions which throw out the greatest number of sparks during
combustion are the best for larger wheels, but will be found also very
effective in the common single triangle.
Those which have a tendency to produce a _flame_, rather than a _jet of
sparks_, are very effective as a variety for _small_ wheels, but produce
an effect comparatively poor when employed for those of greater
dimensions.
For _horizontal_ wheels, _sparkling_ compositions alone are effective,
because in them everything depends upon the form that the fire assumes
_in its outline_, and not upon the shape of the wheel itself.
Compositions which produce but few sparks would be entirely out of place
if used to turn horizontal wheels.