arm of the
artillery has been clearly recognized. Up until the 1800's the weapon
was usually made of bronze, and many mortars had a fixed elevation of
45 deg., which in the sixteenth century was thought to be the proper
elevation for maximum range of any cannon. In the 1750's Mueller
complained of the stupidity of English artillerists in continuing to
use fixed-elevation mortars, and the Spanish made a _mortero de
plancha_, or "plate" mortar (fig. 37), as late as 1788. Range for such
a fixed-elevation weapon was varied by using more or less powder, as
the case required. But the most useful mortar, of course, had
trunnions and adjustable elevation by means of quoins.

[Illustration: Figure 37--SPANISH 5-INCH BRONZE MORTAR (1788).]

The mortar was mounted on a "bed"--a pair of wooden cheeks held
together by transoms. Since a bed had no wheels, the piece was
transported on a mortar wagon or sling cart. In the battery, the
mortar was generally bedded upon a level wooden platform; aboard ship,
it was a revolving platform, so that the piece could be quickly aimed
right or left. The mortar's weight, plus the high angle of elevation,
kept it pretty well in place when it was fired, although English
artillerists took the additional precaution of lashing it down.

The mortar did not use a wad, because a wad prevented the fuze of the
shell from igniting. To the layman, it may seem strange that the shell
was never loaded with the fuze toward the powder charge of the gun.
But the fuze was always toward the muzzle and away from the blast, a
practice which dated from the early days when mortars were discharged
by "double firing": the gunner lit the fuze of the shell with one hand
and the priming of the mortar with the other. Not until the late
1600's did the method of letting the powder blast ignite the fuze
become general. It was a change that greatly simplified the use of the
arm and, no doubt, caused the mortarman to heave a sigh of relief.

[Illustration: Figure 38--SPANISH 10-INCH BRONZE MORTAR (1759-88).
a--Dolphin, or handle, b--Bore, c--Powder chamber.]

Most mortars were equipped with dolphins, either singly or in pairs,
which were used for lifting the weapon onto its bed. Often there was a
little bracketed cup--a priming pan--under the vent, a handy gadget
that saved spilling a lot of powder at the almost vertical breech. As
with other bronze cannon, mortars were embellished with shields,
scrolls, names, and other decor