involved in the Construction of Artillery. 281 



from designs by Capt. Pottinger, E.I.C.S., and which were probably the very 

 earliest British successful attempts in producing forged cannon in one piece, fired 

 by a lock. The chambered breeches of these guns were of soft steel, screwed 

 into the chase ; they were fired by a lock, united with a prolongation of the 

 breech, which ended in a sort of pistol-formed directing handle, and being 

 beautifully balanced on trunnions and a vertical spindle, were directed and 

 fired, from the bow of a boat, by one hand and finger on the trigger, with the 

 facility and accuracy of a shoulder rifle, so that an object in rapid motion could 

 be followed and struck, almost as a sportsman follows a bird upon the wing. 

 Some of these guns were rifled, and the range of all, from the small windage and 

 the density of the lead shot, was surprising, and their practice extremely accu- 

 rate. With the adoption of the Minie form of shot in hardened lead, it can 

 scarcely be doubted that the use of wrought-iron guns of this form, for light 

 horse artillery, would confer a celerity of movement and of practice, combined 

 with range and power, that would be of the highest value in many instances, 

 and more particularly against a mobile and numerous cavalry. 



269. To return from this digression, — the capabilities of the rolling process 

 for producing tubes of wrought-iron, of enormous strength in relation to thick- 

 ness, are well known now to mechanical engineers, since the introduction, some 

 years ago, of the patent process of welding wrought-iron tubes, by rolling at a 

 welding heat, upon a maundrell, either a single, or two flat and equal strips of 

 boiler-plate, which thus become united at the edges by one or by two longitu- 

 dinal welds. This constitutes the process of the Birmingham Patent Tube 

 Company, whose tubes are extensively used for steam-boilers and many other 

 purposes all over the world. 



270. No series of accurate or comprehensive experiments has yet been made 

 as to the relations between diameter, thickness, and strength of these, or indeed 

 any other, tubes, though much to be desired. The author has, however, been 

 obligingly furnished with some results of experiments made specially for him, 

 by the proprietors of these works, of which a few are subjoined, and which 

 prove the enormous resisting powers of these tubes to internal pressure, applied 

 by water, in a very striking manner. (Note U.) 



