Guns & Tunnels
There is a lot to see of the changes made to Fort Siloso over the years. Some things have vanished such as the 64 Pounder and 9.2 Inch Gun emplacements . There are remains traceable to 9.2 Inch Gun in the 6 Inch BL a Magazine. The two 7 Inch RML Guns which overlooked Keppel harbour have also gone.
Right: Gunners at work in a gun emplacement. Photograph courtesy of the Sentosa Leisure Group. Not to be reproduced without permission.
The mixture of names of guns in the fort, such as 7 Inch, 9.2 Inch, 25 Pounder and 64 Pounder, can cause some confusion and requires explanation.
In the early days of artillery, guns were classified by the weight of the solid shot (cannon balls) they fired. This identified the gun's calibre fairly accurately as the size of a cast-iron cannon ball of a given weight did not vary very much. Cannon were themselves built in different sizes and weights, but may still have used the same size of shot, 6 Pounder for example. Some had longer barrels and used a greater propellant charge and became known as ‘Long 6 Pounders’. The size of the cannon was immaterial, 6 pounders fired the same weight of shot.
As the size of cannon increased so did the weight of shot. There were 32 pounders, 64 pounders etc. Other weapons such as mortars and howitzers firing shells rather than solid shot were introduced and muzzle sizes grew. It soon became common for these weapons to be known by their muzzle size, such as 13 Inch Mortar. There were now two methods of identifying guns and in Britain, this was the case until after the Second World War. The move to using the muzzle's diameter may well have been influenced by the weight of shot of the larger weapons as well. A 15 Inch naval shell would weigh 1,920Lbs (872Kg), which would be a bit longwinded as the name for a gun.