[Illustration: Figure 33--SPANISH 4-POUNDER FIELD CARRIAGE (c. 1788).
This carriage, designed on the "new method," employed a handscrew
instead of a wedge for elevating the piece, a--The handspike was
inserted through eyebolts in the trail, b--The ammunition locker held
the cartridges.]
The field guns were the mobile pieces that could travel with the army
and be brought quickly into firing position. They were lighter in
weight than any other type of flat trajectory weapon. To achieve this
lightness the designers had not only shortened the guns, but thinned
down the bore walls. In the eighteenth century, calibers ran from the
3- to the 24-pounder, mounted on comparatively light, two-wheeled
carriages. In addition, there was the 1-1/2-pounder (and sometimes the
light 3- or 6-pounder) on a "galloper" carriage--a vehicle with its
trail shaped into shafts for the horse. The elevating-screw mechanism
was early developed for field guns, although the heavier pieces like
the 18- and 24-pounders were still elevated by quoins as late as the
early 1800's.
In the Castillo collection are parts of early United States field
carriages little different from Spanish carriages that held a score of
4-pounders in the long, continuous earthwork parapet surrounding St.
Augustine in the eighteenth century. The Spanish mounts were a little
more complicated in construction than English or American carriages,
but not much. Spanish pyramid-headed nails for securing ironwork were
not far different from the diamond-and rose-headed nails of the
English artificer.
Each piece of hardware on the carriage had its purpose. Gunner's tools
were laid in hooks on the cheeks. There were bolts and rings for the
lines when the gun had to be moved by manpower in the field. On the
trail transom, pintle plates rimmed the hole that went over the pintle
on the limber. Iron reinforced the carriage at weak points or where
the wood was subject to wear. Iron axletrees were common by the late
1700's.
For training the field gun, the crew used a special handspike quite
different from the garrison handspike. It was a long, round staff,
with an iron handle bolted to its head (fig. 33a). The trail transom
of the carriage held two eyebolts, into which the foot of the spike
was inserted. A lug fitted into an offset in the larger eyebolt so
that the spike could not twist. With the handspike socketed in the
eyebolts, lifting the trail and laying the gun was easy.
The single-trail carriage (fig. 13) used so much during the middle
1800's was a remarkable simplification of carriage design. It was also
essential for guns like the Parrott rifles, since the thick reinforce
on the breech of an otherwise slender barrel would not fit the older
twin-trail carriage. The single, solid "stock" or trail eliminated
transoms, for to the sides of the stock itself were bolted short, high
cheeks, humped like a camel to cradle the gun so high that great
latitude in elevation was possible. The elevating screw was threaded
through a nut in the stock, right under the big reinforce of the gun.
While the larger bore siege Parrotts were not noted for long
serviceability, Parrott field rifles had very high endurance. As for
performance, see the following table:
_Ranges of Parrott field rifles (1863)_
Caliber Weight Type of Projectile Elevation Range Smoothbore
of gun projectile weight of same
(pounds) (pounds) caliber
10-pounder 890 Shell 9.75 5° 2,000 3-pounder.
do 9.75 20° 5,000
20-pounder 1,750 do 18.75 5° 2,100 6-pounder.
do 18.75 15° 4,400
30-pounder 4,200 do 29.00 15° 4,800 9-pounder.
do 29.00 25° 6,700
Long shell 101.00 15° 4,790
do 101.00 25° 6,820
Hollow shot 80.00 25° 7,180
do 80.00 35° 8,453
Amazingly enough, these ranges were obtained with about the same
amount of powder used for the smoothbores of similar caliber: the
10-pounder Parrott used only a pound of powder; the 20-pounder used a
two-pound charge; and the 30-pounder, 3-1/4 pounds!