The 70-pounder Whitworth naval gun was designed by

Joseph Whitworth Sir Joseph Whitworth, 1st Baronet (21 December 1803 – 22 January 1887) was an English engineer, entrepreneur, inventor and philanthropist. In 1841, he devised the British Standard Whitworth system, which created an accepted standard for screw ...

during the 1860s. It was a rifled muzzle loader and used his hexagonal, rifled-bore design.

Principle

The gun used

polygonal rifling Polygonal rifling ( ) is a type of gun barrel rifling where the traditional sharp-edged "lands and grooves" are replaced by less pronounced "hills and valleys", so the barrel bore has a polygonal (usually hexagonal or octagonal) cross-sectional ...

, a principle invented by Whitworth in 1853. The concept was to use the hexagon to impart a very rapid spin to the projectile. The method of manufacturing the rifling was thus described by the Report of the Armstrong & Whitworth Committee of the British War Office (1866):

may be described in general terms as a hexagonal bore with a rapid twist, although, strictly speaking, the bore is not hexagonal, but has 24 surfaces. The gun is, in the first instance, bored out cylindrically; a part of this original bore is left in the centre of each side of the hexagon, making six surfaces, then there are the coming out sides of the hexagon which give six more surfaces, and the going in sides giving also six surfaces, and lastly, the rounding off of the angles, which give six more, making 24 surfaces in all.

The projectile was hexagonal to match. The gun was highly accurate at long ranges, but the very precise manufacturing tolerances required a high standard of maintenance by the artillerymen. Wrote Jeff Kinard: "The odd shape of the projectile produced a weird, unnerving shriek as it traveled through the air."

Service

American civil war

Four guns were captured by the

United States Navy The United States Navy (USN) is the naval warfare, maritime military branch, service branch of the United States Department of Defense. It is the world's most powerful navy with the largest Displacement (ship), displacement, at 4.5 millio ...

on the blockade-runner ''Princess Royal'' on 29 January 1863. Two were sent to

Morris Island Morris Island is an 840-acre (3.4 km2) uninhabited island in Charleston Harbor in South Carolina, accessible only by boat. The island lies in the outer reaches of the harbor and was thus a strategic location in the American Civil War. The i ...

Charleston, South Carolina Charleston is the List of municipalities in South Carolina, most populous city in the U.S. state of South Carolina. The city lies just south of the geographical midpoint of South Carolina's coastline on Charleston Harbor, an inlet of the Atla ...

to bombard

Fort Sumter Fort Sumter is a historical Coastal defense and fortification#Sea forts, sea fort located near Charleston, South Carolina. Constructed on an artificial island at the entrance of Charleston Harbor in 1829, the fort was built in response to the W ...

during the summer of 1863. One gun had a premature detonation that killed four of its crew when trying to ram a projectile home. Another gun was disabled after 111 shots when its inner tube moved back far enough to block the

vent Vent or vents may refer to: Science and technology Biology *Vent, the cloaca region of an animal *Vent DNA polymerase, a thermostable DNA polymerase Geology *Hydrothermal vent, a fissure in a planet's surface from which geothermally heated water ...

Paraguayan war

A number of 70-pounders as well as larger calibers were bought by the

Imperial Brazilian Navy The Imperial Brazilian Navy (Brazilian Portuguese: ''Armada Nacional'', commonly known as ''Armada Imperial'') was the navy created at the time of the independence of the Empire of Brazil from the United Kingdom of Portugal, Brazil and the Algar ...

and used to arm some of its

ironclad An ironclad was a steam engine, steam-propelled warship protected by iron armour, steel or iron armor constructed from 1859 to the early 1890s. The ironclad was developed as a result of the vulnerability of wooden warships to explosive or ince ...

s during the

Paraguayan War The Paraguayan War (, , ), also known as the War of the Triple Alliance (, , ), was a South American war that lasted from 1864 to 1870. It was fought between Paraguay and the Triple Alliance of Argentina, the Empire of Brazil, and Uruguay. It wa ...

in the late 1860s. British lieutenant colonel George Thompson of the Paraguayan army recorded that the Brazilians cut the fuses to the wrong length, so the shells often failed to explode. Thousands of them were collected by the Paraguayans, who made a gun of their own ("a beautiful casting") at their foundry at Asunción – on the Whitworth principle – called the ''Criollo''; this gun shot them back at the Brazilians. Thompson recorded that

For precision and range, Whitworth's guns are splendid weapons, but they require good gunners... Whitworth's balls had such a high velocity, that the report of the gun, and the shot flying by, were both heard at the same moment. The Paraguayans, from the sound these balls made going through the air, called Whitworth's balls 'phews'.Thompson, p. 196

All of the Brazilian river monitors who effected the Passage of Humaitá − described as a nearly impossible feat − were equipped with 70-pounder Whitworth guns; the larger ironclad vessels who accompanied them had Whitworth guns of larger calibre.

Notes

Gallery

PrincessRoyalGunProfile.jpg, On a naval carriage Praia vermelha canhao whitworth 70 lb.JPG, On a coastal carriage in

Rio de Janeiro Rio de Janeiro, or simply Rio, is the capital of the Rio de Janeiro (state), state of Rio de Janeiro. It is the List of cities in Brazil by population, second-most-populous city in Brazil (after São Paulo) and the Largest cities in the America ...

References

* * Alexander Lyman Holley
"A Treatise on Ordnance and Armor" published by D. Van Nostrand, New York, 1865
* * * *

External links

{{USCWWeapons Naval guns of the United Kingdom American Civil War artillery