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.