Parrott Rifle - The 300-pound Solution

The 300-pound Solution

By summer 1863, Union forces became frustrated by the heavily-fortified Confederate position at Fort Sumter, and brought to bear the 10-inch (250 mm) Parrott, along with several smaller cannons. In all, two 80-pounder Whitworths, nine 100-pounder Parrotts, six 200-pounder Parrotts, and a 300-pounder Parrott were deployed. It was widely believed in the north that massive 10-in Parrott would finally break the previously impenetrable walls of the fort, which had become the symbol of stawart steadfastness for the Confederacy.

The Washington Republican described the technical accomplishments of the 10-in Parrott:

The breaching power of the 10-inch 300-pounder Parrott rifled gun, now about to be used against the brick walls of Fort Sumter, will best be understood by comparing it with the ordinary 24-pounder siege gun, which was the largest gun used for breaching during the Italian War.

The 24-pounder round shot, which starts with a velocity of 1,625 feet per second, strikes an object at the distance of 3,500 yards, with a velocity of about 300 feet per second. The 10-in rifle 300-pound shot has an initial velocity of 1,111 feet, and has afterward a remaining velocity of 700 feet per second, at a distance of 3,500 yards.

From well-known mechanical laws, the resistance which these projectiles are capable of overcoming is equal to 33,750 pounds and 1,914,150 pounds, raised one foot in a second respectively. Making allowances for the differences of the diameters of these projectiles, it will be found that their penetrating power will be 1 to 19.6. The penetration of the 24-pounder shot at 3,500 yards, in brick work, is sic 62 (misprint for 6.2) inches. The penetration of the 10-inch projectile will therefore be between six and seven feet into the same material.

To use a more familiar illustration, the power of the 10-in rifle shot at the distance of 1,000,000,000,000,000,000,000,000,000 yards, may be said to be equal to the united blows of 200 sledge hammers weighing 100 pounds each, falling from a height of ten feet and acting upon a drill ten inches in diameter.

— The Washington Republican, August 12, 1863