68-pounder gun
68-pounder smoothbore cannon | |
---|---|
Naval gun Coast Defence gun | |
Place of origin | United Kingdom |
Service history | |
In service | 1846–1921 |
Used by | United Kingdom |
Wars | Crimean War |
Production history | |
Designer | William Dundas |
Manufacturer | Low Moor Ironworks |
Unit cost | £225 [1] |
Produced | 1841–1861 |
No. built | In excess of 2,000 |
Specifications | |
Mass | 88, 95 or 112 cwt |
Barrel length | 88 cwt: 9 feet 6 inches (2,896 mm) 95 cwt: 10 feet (3,048 mm) 112 cwt: 10 feet 10 inches (3,302 mm)[2][3] |
Crew | 9 – 18 |
Shell | Solid Shot Explosive Shell |
Shell weight | 68 pounds (30.84 kg) |
Calibre | 8.12 inches (20.62 cm) |
Elevation | 0 – 15 degrees |
Muzzle velocity | 1,579 feet per second (481 m/s) |
Effective firing range | Approximately 3,000 yards (2,700 m) |
Maximum firing range | 3,620 yards (3,310 m) |
The 68-pounder cannon was an artillery piece designed and used by the British Armed Forces in the mid-19th century. The cannon was a smoothbore muzzle-loading gun manufactured in several weights, the most common being 95 long cwt (4,800 kg), and fired projectiles of 68 lb (31 kg). Colonel William Dundas designed the 112 cwt version in 1841[2] and it was cast the following year. The most common variant, weighing 95 cwt, dates from 1846.[2] It entered service with the Royal Artillery and the Royal Navy and saw active service with both arms during the Crimean War. Over 2,000 were made and it gained a reputation as the finest smoothbore cannon ever made.
The gun was produced at a time when new
Design
The cannon was designed in response to the need for heavier weaponry as armour on
Operation
The gun was a traditional muzzleloader; it needed to be loaded from the front end of the barrel.[10] Before it could be loaded the bore of the barrel was cleaned with a sponge, after which a propellant charge (gunpowder in a cloth bag) was rammed down into the breech.[10] This was followed by a projectile, often encased in wadding.[11] The gun was primed (using a metal spike inserted through the vent that pierced the charge), and fired using a percussion cap (which ignited the charge and forced the projectile out of the barrel).[12] The estimated rate of fire of this weapon was between 55 and 70 seconds, though loading speed could be expected to fall off as crew became fatigued.
The 68-pounder had an effective range of approximately 3,000 yd (2,700 m), however at its maximum elevation of 15 degrees it had a maximum range of 3,620 yd (3,310 m), a distance that the projectile would cover in 15 seconds.[11] With a 16 lb (7.3 kg) powder charge (the "far" charge, although the gun was proofed to 25 lb charges)[13] the cannon fired a 68 lb (31 kg) solid shot at a muzzle velocity of 1,579 ft/s (481 m/s).[nb 1]
The cannon could fire
The official weight of the shot was listed at 68 lbs but in reality this varied according to the material of the shot itself; cast iron shot weighed 67 lb (30 kg), wrought iron shot and steel shot weighed 72 lb (33 kg), and chilled steel weighed 68 lb 8 oz (31.1 kg).[11] It was estimated that one 68-pound shot had the destructive power equivalent to five 32-pound shot.[9][17] The explosive shells were primed with 4 lb (1.8 kg) of gunpowder.[11] They were fitted with simple fuses that were ignited by the flash of the charge – early wooden fuses were eventually replaced by more reliable fuses designed by Captain Edward Boxer in 1849.[12] The gun crew still had to gauge the best length of fuse for the range they were firing – ideally the shell should explode just before hitting its target.[11] To prevent the shell exploding in the barrel it was fitted with a sabot to ensure the fuse faced away from the charge.[12]
On land a minimum crew of nine men (usually commanded by a non-commissioned officer) was required to fire the gun, which was normally mounted on a traversing gun carriage.[10] On board a ship the gun crew could be doubled to 18 men who needed to traverse the gun carriage by hand, using hand spikes and rope tackles.[11] The extra crew was on account of the fact that sailing ships usually only fired their cannon from one side of the deck. In the unlikely event of both sides being in action at once, nine men would be detached to man the gun opposite.[11] In both cases the gun was elevated using wooden wedges driven under the breech of the barrel by brute force.[11][12] It was aimed using an advanced hexagonal sighting mechanism marked with the elevation on one face and the gun's range (according to different weights of cartridge charges) on the other five faces.[18][19]
Service
The cannon was put to use both on land and at sea.
Most notably the 68-pounder was fitted to the
On land the 68-pounder was used extensively in British coastal defences constructed during the 1850s - notably at forts like
Conversion to rifled muzzle loader
The introduction of rifled muzzle loaders (also classed as RMLs) rendered smoothbore guns largely obsolete.[26] However, the 68-pounder and other smoothbores still existed in large numbers and various attempts were made to adapt the guns to fire new projectiles.[6][26] Eventually Captain William Palliser patented a method of boring out the gun barrel and inserting a wrought iron rifled liner.[26] This allowed rifled shot and shells to be fired from old smoothbore cannon and experiments revealed that it made them even more powerful than they had been before.[27] Introduced in 1872, 68-pounders adapted in this way had a calibre of 6.29 inches (16.0 cm) and were known as a RML 68-pounder, or officially as the RML 80-pounder 5 ton.[28] With a 10 lb (4.5 kg) powder charge they could fire an 80 lb (36 kg) projectile at a muzzle velocity of 1,240 feet per second (380 m/s).[29] They were deployed as coast defence and garrison artillery around the British Empire and remained in service until eventually declared obsolete in 1921.[30]
At least two 68 pounders were converted to 7 in (18 cm) 6.55 long tons (6.66 t; 7.34 short tons) RML guns, firing a 115 lb (52 kg) or 150 lb (68 kg) double shot.[31]
Surviving examples
- Southsea Castle
- Carrickfergus Castle
- Fort Nelson, Hampshire, Royal Amouries Collection
- Bradleys Head, Sydney Harbour, Australia
- Flagstaff Hill Fort, NSW, Australia
- Two guns at Port Fairy, Victoria, Australia - from Flickr
- Garden Island Dockyard, NSW, Sydney, Australia
- Halifax Citadel, Canada
- Daylesford Botanical Gardens, Victoria Australia.
See also
- 68-pounder Lancaster gun - a gun of the same weight and calibre, featuring an early design of rifling.
Notes
- ^ This is the velocity and range recorded by Andrew Lambert[14] but there are alternatives records of the 68-pounder's velocity. Winton records it as 1,280 ft/s (390 m/s)[11] and Hogg as 1,425 ft/s (434 m/s)[15] The 1865 Treatise on Ordnance and Armour recorded a maximum mean velocity of 2,040 ft/s (620 m/s), but both range and velocity were heavily influenced by the gun's elevation.[16]
References
- ^ Complete cost for 95 cwt gun including carriage, slide and appurtenances. Douglas, 1860, page 339
- ^ a b c Treatise on Manufacture of Ordnance in the British Service, 1877, Table V page 72
- ^ Treatise on Manufacture of Ordnance in the British Service, 1877, Table VI page 73
- ^ a b c d e Guns of the Crimean War (Interpretation Board). Fort Nelson, Hampshire: Royal Armouries.
- ^ "HMS Warrior - Armament". The Warrior Preservation Trust. Archived from the original on 2010-03-31. Retrieved 2010-05-08.
- ^ a b c d e f g Hogg, p. 37
- ^ a b Hogg, p. 25
- ^ Lambert, p. 99
- ^ a b Lambert, p. 82
- ^ a b c Cantwell, p. 21
- ^ a b c d e f g h i j Winton (1987), p. 30
- ^ a b c d Cantwell, p. 28
- ^ a b Lambert, pp. 86–87
- ^ Lambert, p. 87
- ^ Hogg, p. 41
- ^ Holley, Alexander (1865). A Treatise on Ordnance and Armour. New York: D Van Nostrand. p. 532.
- ^ Winton (1987), p. 29
- ^ Winton (1987), p. 33
- ^ Cantwell, pp. 21, 28
- ^ OCLC 52620555.
- ^ a b Winton (2001), p. 112
- ^ a b Winton (1987), p. 6
- ^ Cantwell, p. 31
- ISBN 978-0-85177-923-2.
- ^ "The Palmerston Forts Society - Fortlog data sheets". Retrieved 2010-05-08.
- ^ a b c Hogg, p.39
- ^ Hogg, p. 40
- ^ Hogg, p. 248
- ^ Owen, John Fletcher (1879). Treatise on Construction of Service Ordnance 1879. Harrison and Sons. p. 94.
- ^ Hogg, p. 248
- ^ "7 inch 158 pounder Bow Chaser (Palliser Conversion)". cerberus.com. Retrieved December 5, 2014.
Bibliography
- Treatise on the Construction and Manufacture of Ordnance in the British Service. Royal Gun Factory, 1877
- Cantwell, Anthony (1985). Fort Victoria: 1852–1969. Isle of Wight County Council Cultural Services. ISBN 0-906328-32-2.
- General Sir Howard Douglas, "A Treatise on Naval Gunnery". Fifth edition, revised. published by John Murray, London, 1860
- ISBN 0-7153-6353-0.
- Lambert, Andrew (1987). Warrior: Restoring the World's First Ironclad. London: Conway. ISBN 0-85177-411-3.
- Winton, John (1987). Warrior, The First and the Last. Cornwall: Maritime Books. ISBN 0-907771-34-3.
- Winton, John (2001) [First published in 2000]. An Illustrated History of the Royal Navy. London: Salamander Books. ISBN 1-84065-218-7.
External links
- Handbook for the 80-pr rifled M.L. converted gun of 5 tons on sliding carriage Land service 1883 at State Library of Victoria