﻿18 ON CONSTRUCTING CANNON OF GREAT CALIBER. 



"With them, therefore, this pouuding of the ball, being repeated a few hundred times, 

 shatters the walls of the gun, which at length gives way at once and goes to pieces. 



It must be obvious, that, if the lodgment be attributed to either or both of the 

 causes which I liave recited, it may be prevented by a most simple and easy means. 

 This is nothing more than pronding that the ball shall, at the moment of the ex- 

 plosion of the powder, have no part in contact with the bore of the gun, but that the 

 windage space shall be equally distributed about the whole circumference. This 

 may be entirely secured by enveloping the ball in a bag made of felt, or of hard 

 woollen cloth, having an additional patch upon its under side to compensate for the 

 weight of the ball. It would seem impossible that in tliis condition the ball, receiving 

 the pressure of the powder equally distributed in the direction of the axis of the 

 caliber, should touch the gun more than by a slight graze dm'ing its flight.* 



* My observations upon the lodgment have been made upon wrought-iron cannon. Between the years 

 1841 and 1845, I made upwards of twenty cannon of this material. They were all made up of rings, or 

 short hollow cylinders, welded together endwise. Each ring was made of bars wound upon an arbor 

 spirally, like winding a ribbon upon a block, and, being welded and shaped in dies, were joined endwise, 

 when in the furnace and at a welding heat, and afterwards pressed together in a mould by a hydrostatic 

 press of 1,000 tons' force. Finding in the early stage of the manufacture that the softness of the wrought 

 iron was a serious defect, I formed those made aftenvards with a lining of steel, the wrought-iron bars being 

 wound upon a previously formed steel ring. Eight of these guns were 6-pounders of the common United 

 States bronze pattern, and eleven were 32-pounders of about 80 inches' length of bore, and 1,800 pounds' 

 weight. Six of the 6-pounders, and four of the 32-pounders, were made for the United States. They have 

 all been subjected to the most severe tests. One of the 6-pounders has borne 1,560 discharges, beginning 

 with service charges and ending with 10 charges of 6 pounds of powder and 7 shot, without essential injury. 

 It required to destroy one of the 32-pounders a succession of charges ending with 14 pounds of powder 

 and 5 shot, although the weight of the gun was but 60 times the weight of the proper shot. If any of 

 these guns are ever destroyed by firing them, the destruction will commence in the lodgment. 



It was during a course of experimental firing with the soft wrought-iron gun, that I had an oppor- 

 tunity of observing the formation and increase of the lodgment; and here I was led to the experiment of 

 placing the shot in a bag, as recommended in the text. My experiments were not sufficiently extended 

 and varied to lead me to an assured conviction that the evil may be entirely prevented by this practice ; 

 but they were enough to lead me to a confident expectation of that result, as I could never detect the 

 formation of any lodgment or any increase in one previously formed when the bag was used. 



I cannot leave this subject without observing that I regard the late, and still continued, attempts to make 

 wrought-iron cannon in Europe by the process oi fagoting or piling, as a strange engineering delusion. 

 It may not surprise us that amateur engineers, whose whole knowledge of the character of iron is derived 

 from a printed page, should expect useful results from this attempt. But that men practically acquainted 

 with working iron should expect to forge a serviceable gun of wrought-iron by the same process that is 

 used to produce a shaft of that material, seems to me not very creditable to the iron knowledge of the age. 



