Part 6 (2/2)

4.5 inches Thickness of cheek 5.8 inches.

50 inches Wheel diameter 58 inches.

6x8x68 inches Axletree 7x9x81 inches.

Heavy siege guns were elevated with quoins, and elevation was restricted to 12 or less, which was about the same as United States siege carriages permitted in 1861. It was considered ample for these flat trajectory pieces.

Both field and siege carriages were pulled over long distances by lifting the trail to a horse-or ox-drawn limber; a hole in the trail transom seated on an iron bolt or pintle on the two-wheeled limber.

Some late eighteenth century field and siege carriages had a second pair of trunnion holes a couple of feet back from the regular holes, and the cannon was s.h.i.+fted to the rear holes where the weight was better distributed for traveling. The United States siege carriage of the 1860's had no extra trunnion holes, but a ”traveling bed” was provided where the gun was cradled in position 2 or 3 feet back of its firing position. A well-drilled gun crew could make the s.h.i.+ft very rapidly, using a lifting jack, a few rollers, blocks, and chocks. When there was danger of straining or breaking the gun carriage, however, ma.s.sive block carriages, sling carts, or wagons were used to carry the guns.

Sling wagons were of necessity used for transport in siege operations when the guns were to be mounted on barbette (traversing platform) carriages (fig. 10). Emplacing the barbette carriage called for construction of a ma.s.sive, level subplatform, but it also eliminated the old need for the gunner to chalk the location of his wheels in order to return his gun to the proper firing position after each shot.

The Federal sieges of Forts Pulaski and Sumter were highly complicated engineering operations that involved landing tremendously heavy ordnance (the 300-pounder Parrott weighed 13 tons) through the surf, moving the big guns over very difficult terrain and, in some cases, building roads over the marshes and driving foundation piles for the gun emplacements.

The heavy caliber Parrotts trained on Fort Sumter were in batteries from 1,750 to 4,290 yards distant from their target. They were very accurate, but their endurance was an uncertain factor. The notorious ”Swamp Angel,” for instance, burst after 36 rounds.

FIELD CANNON

[Ill.u.s.tration: 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 lat.i.tude 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 Sh.e.l.l 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 sh.e.l.l 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!

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