THE ROYAL ARTILLERY INSTITUTION. 
345 
APPENDIX, No. II. 
Me NASMYTH’S GUN. 
REPORT OF THE SUPERINTENDENT ROYAL GUN FACTORIES, ON THE 
BURSTING OF 32-pr. No. 4475, AFTER ITS CONYERSION INTO A BREECH¬ 
LOADER ON Mr NASMYTH’S PLAN. 
Royal Gttn Factories, 
27th September, 1859. 
Sir, 
The following is a Report of experimental practice with a 32-pr. service 
gun (converted into a breech-loader agreeably to Mr Nasmyth's plan), 
carried on at the proof butt, Plumstead Marshes, as per requisition of the 
Ordnance Select Committee, 15th September, 1859. 
The gun selected for this experiment was made at the Lowmoor Works, 
and supplied by Mr Hood. 
* Nature, 32-pr. {^^ 8621 
Weight . 58 cwt. 3 qrs. 
Length . 9 feet 6 inches. 
Calibre. 6*375 inches. 
Cast 26th April, 1859. 
Proved 1st June, with the following charges, viz.— 
Powder, 1 cartridge . 21^ lbs. 
Shot solid, weight . 32 „ 
Wads, junk. 2 
After firing two rounds with the above charges, the gun was searched, 
water-proved, and declared serviceable. 
Under the directions of Mr Nasmyth, this gun was fitted in the Royal 
Gun Pactories Department with a screw breech plug, worked by a 5 ft. lever. 
The plug is made of wrought-iron from best selected scrap; it is 12J 
inches in its entire length, 9J inches of which is screwed with a V thread, 
rounded at the top and bottom, w 7 hich fits into a corresponding length 
prepared for it in the gun. 
The angle of the side of the thread =60°. Pitch of the thread=-J inch. 
The point of the plug is cylindrical (diameter 6*8 inches), terminating in 
a frustrum of a cone (slant height -§ inch) which fits into a recess made for 
it in the bore of the gun. 
Diameter of plug at the breech end=8T inches. 
Exterior diameter of thread next the chamber = 8 inches. 
The screw is therefore slightly tapering, which facilitates its insertion and 
removal. 
A tapering hexagonal hole is slotted out of the breech plug, into which is 
inserted a corresponding solid pin of wrought-iron, terminating in a knob. 
Through this knob the lever is passed for working the screw. 
Weight of screw, 133 lbs. 
