67. We now come to a very useful and effective feature in pyrotechnic
displays, which, although rather short-lived in its performance,
produces quite as much aërial decoration as any piece that can be
employed. I speak of the mine, whether charged with serpents or
crackers.
It would be difficult to find a better single accompaniment to the
concluding piece of a small exhibition than a really good serpent mine.
But these pieces need not necessarily be used as accompaniments; they
may also be made up as separate pieces. Of these combinations I shall
speak hereafter.
And first, for the information of those who do not know what a mine is,
or what its performance is, I may say that it consists of a cylindrical
box, made either of thick paper or iron; and this box contains a number
of small serpents having reports; these serpents are placed in the box
in such a manner that their mouths may all readily take fire at the same
instant, at which instant they are blown out of the box to the height of
fifty or sixty feet in the air, where they be-have themselves in a most
lively and somewhat eccentric manner, until a smart pop from each brings
their gambols to a close by turning their carcasses inside out.
[Illustration: [Fleuron]]
Now comes the question, “How are we to charm these little serpents into
doing as we please?” The following answer to this question will, I
trust, leave nothing unexplained or difficult of comprehension.
In the first place, with regard to the serpents themselves, I cannot
think that you will find it worth your while to be troubled with the
manufacture of them. The work is dirty, troublesome, and rather
expensive, because you can do nothing without a choking apparatus proper
for this purpose, and when you set in array against these disadvantages
the very low price of the serpents, as you can buy them of Mr. Darby, of
98 Regent Street, Lambeth, which is, I believe, at the rate of three
shillings per gross, primed and ready for use, I think you will agree
with me that the best plan is to wash your hands altogether of their
manufacture, and to buy them where you can depend upon their being
uniformly good and reasonable in price.
These serpents are generally about two inches and three-quarters in
length, and are of a very convenient size for the purpose. I will
suppose that you have provided yourself with some of these, and that you
want to make one of such serpent mines as can be bought at the firework
shops.
The first thing for you to do is to decide upon the size of mine that
you require. In my opinion, very small mines are not worth making. I
should never think of putting less than _two dozen_ serpents into a
mine. If you will take my advice you will determine upon one or two
sizes, and keep to them; you will find this by far the most convenient
plan.
The two sizes which I should recommend are those whose cases are _two
inches and a-half_ and _three inches_ in diameter. The latter will
discharge three dozen serpents, and will, I think, be found large enough
for all purposes.
If you want a former round which to make the case, _or mortar_, as it is
called, of the two and a-half inch size, you can generally find one
ready made at the draper’s. They have them as rollers for silks, &c.,
and the above is one of their sizes. I have found one of these very
convenient.
In the next place you must always keep your eye on the look-out for old
odd pieces of thick brown paper, or sugar paper, or any thick paper used
for parcels, and turn them to account; any old pieces of cardboard may
also be worked in. You will want a case or mortar _seven inches long_,
and so well pasted and closely rolled that you can hardly bend it with
your fingers. Do not spare the paste, nor imagine that you can dispense
with the roller board. Well paste the former and all the paper, and when
you have finished the mortar, set it by, and do not use it till it is
thoroughly dry and hard, but at the same time do not attempt to hurry
the drying over, and so warp it and put it out of shape.
You will now have a round hard cylinder of pasteboard, open at both
ends. Cut a piece of deal or other wood, of a size that will fit tightly
into one of these ends, and _about an inch thick_, and glue it in, to
make a firm bottom to the mortar, so that it has no chance of coming
out.
Now weigh out one-ounce of common gunpowder; such as is sold at the
shops at about 1s. per pound is quite good enough for this purpose. Put
this into a piece of _thin_ paper, and make it up into a neat little
flat circular parcel as shown at fig. 105. It should be as nearly as
possible the same size as the interior of the mortar. You will find that
the mortar of the two and a-half inch size is capable of holding about
twenty-eight serpents. But, whatever sized former you use for the
mortar, ascertain how many serpents will be required to fill it,
remembering that they are by no means required to fit in tightly; that
if they are fitted in tightly your mortar is pretty sure to be blown to
pieces, which catastrophe is by all means to be avoided. Having
ascertained the number of serpents required, tie them into a bundle with
cotton. This will enable you to pass them without any trouble into the
mortar. But before putting them in take out the centre serpent, and tie
to its neck a piece of quick-match in the manner represented in fig.
106. This match is to convey the fire to the mouths of the serpents, and
so on to the packet of powder. When the piece of match has been attached
as directed above, replace the serpent in the midst of the bundle. Take
notice that that part of the match which projects beyond the mouth of
the serpent _is to be uncovered_—that is, is to have its case cut away
from it.
Now in order to insure the proper lighting of all the serpents, I
have adopted a plan which I have always found successful. The usual
plan is to smear the flat side of the packet of gunpowder with
meal-powder-paste, and to let the serpents stand mouth downwards
upon this. I am well aware that many good mines are made in this
way, but I must think that their success is the result rather of
chance than of anything else. I have experimented a great deal in
this direction. I have fired mines so prepared in a place where I
have been able to pick up the remains of the serpents after the
explosion of the mines, and I have frequently found serpents that
had never taken fire at all. And this fact set me to work upon
discovering some new plan. I at once hit upon the cause of former
failures, imagining them to be due to the too rapid ignition of the
powder, which had not allowed time enough for the fire to be
conveyed to the mouths of _all_ the serpents. In attempting to
rectify this, I naturally enough ran to the other extreme, and gave
them rather too long a time, so that they actually found their way
out of the mortar by their own force, and the powder expended itself
in a mighty puff just when they were out of the reach of its
influence. Of course the serpents only found their way just out of
the mortar, and did not produce that lively effect in the air which
was intended. So then I had recourse to the plan which I now adopt,
and which has never failed me. I take some circles of thin blue
paper—such paper as the pyrotechnists use for making into
touch-paper, which is called _thin blue double crown_; these circles
I cut of such a size that they will just pass into my mortar, and I
smear them well over with meal-powder-paste made with meal-powder
moistened with thin starch or gum-water. One of these circles I
place between the packet of powder and the mouths of the serpents.
And I find that this arrangement just allows time enough for the
fire to be conveyed to all the serpents before the packet of powder
is exploded.
You will now have the three principal parts of the mine ready to put
into the pasteboard mortar. In order to do this, take your bundle of
serpents and hold them _mouths upwards_, as represented at fig. 107, and
on their mouths lay the primed circle of thin paper, _meal-powder side
downwards_. On this lay the packet of gunpowder, with its _smooth side
downwards_, and its tied side upwards. Then taking the mortar, _bottom
upwards_, pass it over the whole in the way in which an extinguisher is
used. The mine, thus far completed, is now to be turned the proper way
upwards, and a knife or pair of scissors passed into it to divide the
cotton which bound the serpents together. Care must be taken that this
little piece of after-work is not forgotten and left undone, otherwise
your serpents will come out in a lump, and will not be able to spread.
But now we come to the case which is to play before the mine is fired.
This may be a short case of the one-ounce or two-ounce size, and may be
filled with the beautiful old composition called spur-fire. The
composition for this is—
Nitre 18 parts.
Sulphur 8 „
Lampblack 6 „
But there is a great deal of art in preparing this composition. The
ingredients require to be well-sifted together, and then rubbed together
in a large mortar with a wooden pestle. You must have two or three short
choked cases ready while this pestle and mortar operation is going on,
in which to try the composition at different stages of its progress. If
the ingredients have not been sufficiently rubbed with the pestle, very
few of the beautiful spur-shaped sparks will be thrown out. But if, on
the other hand, too much rubbing has taken place, the composition will
burn too fiercely, and will throw out only drossy sparks. There is
certainly a good deal of patience necessary in the preparation of this
spur-fire composition, but when properly made it will repay you for all
the trouble it has given. It is better to make a good large batch of it
at a time. It is said to improve after being rammed into cases a long
time.
There is only one disadvantage that I have ever found in this spur-fire,
and that is, that much of its beautiful effect is lost unless the
spectators are very close to it when it is fired. The scintillating
sparks may be caught in the hand without danger.
But there are many other compositions which will answer very well for
the beginning case for a mine. For instance, you may use—
Meal-powder 2 parts.
Steel filings 1 part.
Or,
Meal-powder 2 parts.
Iron borings 1 part.
Or,
Meal-powder 4 parts.
Charcoal 1 part.
These compositions may be rammed into either one-ounce or two-ounce
cases, and primed in the ordinary way. The tail end of the case must be
left open, in order to insert the end of the match which comes out of
the bundle of serpents.
You will next require a circular piece of millboard, of a size that will
answer as a lid to your pasteboard mortar. Through the centre of this
lid bore a hole with a centre-bit just the size of the case that you
mean to insert; and when you have decided how far this case shall
project out of the lid, make a mark, and glue the case into the central
hole: and when you have made the necessary connection between the tail
of the fountain-case and the quick-match from the bundle, the lid is
ready to be pasted on. If, however, there is any chance of the mine
being knocked about before it is fired, fill in the space above the
serpents with waste paper, or, still better, with common wadding, _which
does not burn_.
It only remains now to paste a strip of thin paper neatly round the top
of your mortar, so as to secure the lid, and then to put some
touch-paper to your fountain-case, and the piece is ready for firing.
There is another way of making these mines which you can adopt if you
please. Instead of using a short fountain-case, a long one is employed
which will reach down to the smeared meal-powder pad. This case has, of
course, to pass through the bundle of serpents, and so takes up a good
deal of room among them. If you employ a long case of this kind, you
will find it best to use one of the sparkling compositions given above,
_and not the spur-fire_; or, at all events, if the spur-fire is used,
only half fill the case with it. It is a slow-burning composition, and
answers much better in _short_ cases of large calibre than in long cases
of small bore.
For a mine two inches in diameter the charge of powder should be
three-quarters of an ounce. The mortar should be about six inches high.
For a mine two and a-half inches in diameter, and seven inches high, the
charge of powder should be one-ounce.
For a mine three inches in diameter, and eight inches high, the charge
should be an ounce and a-half.
But I must now proceed to tell you of another way of making mines for
exhibition purposes which can be fired at any given moment. These are
fired from iron mortars. One of these mortars will last a lifetime. The
size that I use is that which has a diameter of three inches. The mortar
is made of thick sheet-iron, rivetted firmly into the form of a
cylinder, with an iron ring round its mouth, and a wood block screwed
into its other end for a foot. This mortar has a clear depth of eight
inches inside, and is capable of throwing three dozen serpents. The
exterior of the iron cylinder is bound round with cord, which is
supposed to give it great additional strength. So much for the mortar
from which these exhibition mines are fired. The serpents, powder, &c.,
are contained in paper bags, and have a projecting piece of match by
which they are fired. I have a solid cylinder of wood, six inches long,
and two and three-quarter inches in diameter, upon which I make my paper
bags for these mines. A former of this size makes a bag that will
contain the three dozen serpents, and will at the same time pass easily
into the mortar. The powder, meal-pad, serpents and quick-match are to
be put in precisely in the same manner as that directed above: the
powder packet at the bottom, of course, then the meal-pad, then the
serpents. After all are inclosed, feel with the fingers for the string
that ties the serpents together, and cut through the paper of the bag
and this string to liberate them. Your mine will then be ready for
firing. Any number of these bags can be fired one after another from the
same iron mortar.
You will find a sketch of a pasteboard mortar at fig. 108, showing its
contents and the fountain-case. You will find also a sketch of an iron
mortar, fig. 109, and bag and serpents, fig. 110; such as I use, which
is by far the most convenient way of exhibiting serpent mines.