MECHANICS AND USEFUL ARTS. 107 



"The improvement in fire-avms, both great and small, is in 

 their increased range and precision, Wlien the efiective range of 

 a mnsket-ball was extended from two hundred yards to fourteen 

 hundred or more, it became imperatively necessary that ordnance 

 should be improved in the same ratio, or it would be useless, as 

 gunners and horses would be picked off by small arms long Iiefore 

 they could effectively reach the enemy. This improvement in 

 guns of great calibre has been made, with consequences the 

 imjjortance of which, present and prospective, cannot be over-esti- 

 mated. 



" But the point which we have to consider is, that this increased 

 range and precision are entirely dependent on the augmented 

 strength of the gun. The weakness of the gun is the only thing 

 that imj^oses a limit to the range short of the absolute strength of 

 the explosive material used. It is the strength of the gun which 

 not only gives the range, but makes rifling possible, with preci- 

 sion and all the advantages of the elongated shot. All inventions re- 

 lating to the different modes of rifling, the form of the projectile, 

 and the devices for breech-loading, are necessarily subordinate to 

 the question of strength : with this sufficient, those become simj^le 

 problems, to be rapidly determined by the ingenuity of many 

 inventors. 



" Now the limit of strength of cast-iron and of bronze cannon 

 had long ago been reached. Excepting Captain Rodman's im- 

 provement, and certain modern advantages in working and cast- 

 ing metals, no material advantages had been gained over guns 

 cast in the reign of Queen Elizabeth. 



" But the most effective guns of the present day embody new 

 principles of strength. They ai-e all built-up guns. With them 

 are associated the names of Armstrong, Blakely,.Whitworth,Par- 

 rott, and others. Whatever may be the relative merits of these 

 several varieties, our interest is confined to the question of their 

 strength, that is, to the principles of construction which have made 

 them stronger than common guns, and rendered their respective 

 subordinate imi^rovements possible. 



"These principles are two, and their introduction at different 

 times into the manufacture of cannon constitute two successive 

 steps, and the only steps, which give distinctive character to the 

 guns under consideration. Both originated with Mr. Treadwell. 



"These two inventions are often confounded, although moi-e 

 than ten years elapsed between them. The confusion is doubtless 

 owing in some degree to the fact that the two are found combined 

 in nearly all the modern built-up guns. The first initiated a sys- 

 tem of construction which may be designated as the coil system ; 

 the second, what may be named the hoop system. 



" The first was successfully applied to the making of cannon by 

 Mr. Treadwell in the year 1842, and a full account of it was pub- 

 lished in 1845 : the gist of the invention being' in so constructing 

 the gun that the fibres of the material shall be directed around the 

 axis of the calibre. 



"This method of construction is descriljed in Professor Tread- 

 weirs own language as follows : ' Between the years 1841 and 



