Aigrettes

Mortars to throw aigrettes are generally made of pasteboard, of the

same thickness as balloon mortars, and two diameters and a half long

in the inside from the top of the foot: the foot must be made of elm

without a chamber, but flat at top, and in the same proportions as

those for balloon mortars; these mortars must also be bound round with

a cord: sometimes eight or nine of these mortars, of about three or

four inche diameter, are bound all together, so as to appear but one;

but when they are made for this purpose, the bottom of the foot must

be of the same diameter as the mortars, and only half a diameter high.

The mortars being bound well together, fix them on a heavy solid block

of wood. To load these mortars, first put on the inside bottom of each

a piece of paper, and on it spread one ounce and a half of meal and

corn-powder mixed; then tie the serpents up in parcels with

quick-match, and put them in the mortar with their mouths downwards;

but take care the parcels do not fit too tight in the mortars, and

that all the serpents have been well primed with powder wetted with

spirit of wine. On the top of the serpents in each mortar lay some

paper or tow; then carry a leader from one mortar to the other all

round, and then from all the outside mortars into that in the middle:

these leaders must be put between the cases and the sides of the

mortar, down to the powder at bottom: in the centre of the middle

mortar fix a fire-pump, or brilliant fountain, which must be open at

bottom, and long enough to project out of the mouth of the mortar;

then paste papers on the tops of all the mortars.



Mortars thus prepared are called a nest of serpents. When these

mortars are to be fired, light the fire-pump, which when consumed will

communicate to all the mortars at once by means of the leaders. For

mortars of 8, 9, or 10 inches diameter, the serpents should be made in

one and two-ounce cases, six or seven inches long, and fired by a

leader brought out of the mouth of the mortar, and turned down on the

outside, and the end of it covered with paper, to prevent the sparks

of the other works from setting it on fire. For a six-inch mortar, let

the quantity of powder for firing be two ounces; for an eight-inch,

two ounces and three-quarters; and for a ten-inch, three ounces and

three-quarters. Care must be taken in these, as well as small mortars,

not to put in the serpents too tight, for fear of bursting the

mortars. These mortars may be loaded with stars, crackers, &c.



If the mortars, when loaded, are sent to any distance, or liable to be

much moved, the firing powder should be secured from getting amongst

the serpents, which would endanger the mortars, as well as hurt their

performance. To prevent this, load the mortars thus: First put in the

firing powder, and spread it equally about; then cut a round piece of

blue touch-paper, equal to the exterior diameter of the mortar, and

draw on it a circle equal to the interior diameter of the mortar, and

notch it all round as far as that circle: then paste that part which

is notched, and put it down the mortar close to the powder, and stick

the pasted edge to the mortar: this will keep the powder always smooth

at bottom, so that it may be moved or carried anywhere without

receiving damage. The large single mortars are called pots des

aigrettes.





FIRE-PUMPS, OR ROMAN CANDLES.



Cases for fire-pumps are made like those for tourbillons; only they

are pasted instead of being rolled dry. Having rolled and dried your

cases fill them: first put in a little meal-powder and then a star, on

which ram, lightly, a ladle or two of composition, then a little

meal-powder, and on that a star; then again composition, and so on

till you have filled the case. Stars for fire-pumps should not be

round, but must be made either square, or flat and circular with a

hole through the middle: the quantity of powder for throwing the stars

must increase as you come near the top of the case; for, if much

powder be put at the bottom, it will burst the case. The stars must

differ in size in this manner: let the star which you put in first be

a little less than the bore of the case; but let the next star be a

little larger, and the third star a little larger than the second, and

so on: let them increase in diameter till within two of the top of the

case, which two must fit in tight. As the loading of fire-pumps is

somewhat difficult, it will be necessary to make two or three trials

before you depend on their performance. When you fill a number of

pumps, take care not to put in each an equal quantity of charge

between the stars, so that when they are fired they may not throw up

too many stars together. Cases for fire-pumps should be made very

strong, and rolled on 4 or 8-ounce formers, 10 or 12 inches long each.



CHARGE.

lb. oz. lb. oz.

Saltpetre 5 0 Saltpetre 5 0

Brimstone 1 0 Brimstone 2 0

Meal-powder 1-1/2 0 Meal-powder 1 8

Glass-dust 1 0 Glass-dust 1 8





AN ARTIFICIAL EARTHQUAKE.



Mix the following ingredients to a paste, with water; bury it in the

ground, and in a few hours the earth will break open in several

places:



lb. oz.

Sulphur 4 0

Steel-dust 4 0