t the muzzle of the gun, when fully elevated, butt against the sill
over the gun port.

On the eighteenth century Spanish garrison carriage (fig. 28), no
bolts were threaded; all were held either by a key run through a slot
in the foot of the bolt, or by bradding the foot over a decorative
washer. Compared with American mounts of the same type (figs. 30 and
31), the Spanish carriage was considerably more complicated, due
partly to the greater amount of decorative ironwork and partly to the
design of the wooden parts which, with their carefully worked
mortises, required a craftsman's skill. The cheek of the Spanish
carriage was a single great plank. English and American construction
called for a built-up cheek of several planks, cleverly jogged or
mortised together to prevent starting under the strain of firing.

[Illustration: Figure 30--ENGLISH GARRISON CARRIAGE (1756). By
substituting wooden wheels for the cast-iron ones, this carriage
became a standard naval gun carriage.]

Mueller furnished specifications for building truck (four-wheeled)
carriages for 3- to 42-pounders. Aboard ship, of course, the truck
carriage was standard for almost everything except the little swivel
guns and the mortars.

Carriage trucks (wheels), unless they were made of cast iron, had iron
thimbles or bushings driven into the hole of the hub, and to save the
wood of the axletree, the spindle on which the wheel revolved was
partly protected by metal. The British put copper on the _bottom_ of
the spindle; Spanish and French designers put copper on the _top_,
then set iron "axletree bars" into the bottom. These bars strengthened
the axletree and resisted wear at the spindle.

A 24-pounder fore truck was 18 inches in diameter. Rear trucks were 16
inches. The difference in size compensated for the slope in the gun
platform or deck--a slope which helped to check recoil. Aboard ship,
where recoil space was limited, the "kick" of the gun was checked by a
heavy rope called a breeching, shackled to the side of the vessel
(see fig. 11). Ship carriages of the two-or four-wheel type (fig. 31),
were used through the War between the States, and there was no great
change until the advent of automatic recoil mechanisms made a
stationary mount possible.

[Illustration: Figure 31--U. S. NAVAL TRUCK CARRIAGE (1866).]

With garrison carriages, however, changes came much earlier. In 1743,
Fort William on the Georgia coast had a pair of 18-pounders mounted