G2 ANNUAL OF SCIENTIFIC DISCOVERT. 



what is believed to be the excessive pitch in the mode of ribbed rifling 

 adopted by Mr. Thomas. 



Sir William Armstrong then fired his 300-pounder with an ordinary 

 cast-iron round shot, weighing 144 Ibs., with a charge of 45 Ibs. of pow- 

 der. The terminal velocity with which this struck the 7l-inch plate 

 on the unbacked portion was the highest attained no less than 1,636 

 feet a second - - and almost in exact proportion to its velocity was the 

 damage it inflicted. Not only was it indented larger and deeper than 

 any shot that had gone before, but on the inner side it broke the plate 

 both vertically and horizontally, leaving a cruciform tear nearly two 

 inches wide at the openings, besides shaking the target to its very 

 foundations. 



The massive target was now so much damaged, both in plates and 

 fastenings, that further experiments became almost useless. The iron, 

 even where most torn, held together in a manner that was really won- 

 derful ; but Mr. Thomas had knocked off several of the massive screw 

 bolt heads, and the effect of the entire day's work had been so to bend 

 the plates and destroy the backing that there was really no part left 

 that afforded the means of a fair test of resistance. 



The practical results elicited by the day's experiments seem to be 

 these first, that iron plates of 71 inches, or greater thickness, can be 

 produced with as much perfection, as to quality and strength, as those 

 of 4 inches ; secondly, that there are guns the fire of which the strong- 

 est armor-clads could not face and float for ten minutes. 



Perhaps the most remarkable fact connected with these experiments 

 was the smashing of the target with a cast-iron shell. From previous 

 experiments it had been concluded that all cast-iron shot would break 

 in pieces in striking thick wrought-iron plates. 



The Armstrong Gun.-- Confidence in the Armstrong gun in Great 

 Britain has been greatly diminished during the past year, both from 

 the public discussion of its merits in the public prints, and through the 

 publication of the report of a government committee appointed to in- 

 quire into the whole subject. 



According to the Western Morning Mail, Mr. Armstrong has, since 

 the commencement of his appointment of government gun-founder, 

 " constructed not less than ten different kinds of guns ; that of each 

 kind he made and put into the government's hands a considerable num- 

 ber, and was paid for them, and that not one of all these cannon has 

 proved serviceable without great and expensive alterations. He made, 

 1 1 0-pounders, 120-pounders, both muzzle and breech loading ; 150- 

 pounders, 300-pounders, 200-pounders, 12-pounders, 40-pounders, 100- 

 pouuders ; and the only guns of all these which are even claimed to be 

 successful arc the 12-pounders. But of these we read that they have 

 been returned and are now having twelve inches cut off the muzzle to 

 make them safe. They will, consequently, when 'fixed,' be only 

 9-pounders, with a diminished range." 



There are a number of Armstrong guns now in use in the British 

 navy, 1 1 0-pounders for the most part, but the committee report that 

 '^although useful as chase guns, they ought not to be introduced as broad- 

 side guns." The report adds that they are " not sufficiently powerful 

 to penetrate iron-plated ships, and are imperfect for general naval ser- 

 vice, owing to the diiliculty of managing and manuiacturing the vent 



