66 ANNUAL OF SCIENTIFIC DISCOVEEY. 



India Rubber Breech Piece for Cannon. Numerous patents have 

 recently been taken, both in this country and Europe, for devices to 

 lessen the strain and liability of explosion in ordnance by the use of 

 vulcanized 'India-rubber or gutta-percha applied in the breech to con- 

 fine the air, against which the exploded powder will act, whereby the 

 sides of the bore are relieved from the immense strain of the ignited 

 charge. The objects of these inventions are to lessen the danger of 

 explosion and enable the gun to give a greatly-increased velocity to the 

 shot by using a larger charge of powder than is allowed or deemed safe 

 in the old kind of guns. A device recently patented by Horace H. 

 Day, of New York, consists essentially in inserting into the bottom of 

 the bore of the gun an India-rubber breech piece, or cushion, having 

 a conical recess at its base. Upon the top of this the charge and pro- 

 jectile are inserted in the usual manner. It was claimed that the effect 

 of this elastic cushion is to impart a gradual movement at the moment of 

 explosion, which starts the bolt gently from its seat ; the gases then follow 

 it up and expel it with as much force as the powder is capable of ex- 

 erting. During the past year, a series of experiments to test this 

 invention have been made under the direction of the U.' S. Ordnance 

 Bureau ; the gun employed, in part, being a 130-pounder, filled with 

 a vulcanized rubber breech-piece, 8 inches in length, .2 of an inch 

 smaller in diameter than the bore of the gun, with its rear shaped to 

 fit the bottom of the bore. Its weight was 22 Ibs. The projectile was 

 a solid shot, weighing 126 Ibs., fired into a bank of earth at 85 feet dis- 

 tance. The following is the official record of three firings :--"!. Rub- 

 ber breech-piece was blown out and struck the bank. 2. Rubber 

 breech-piece started forward 501 inches. While sponging the gun out, 

 several small pieces of rubber w"ere found. On examining the breech, 

 found it badly torn. 3. The rubber breech-piece was blown out, and 

 fell fifty feet to the front of the muzzle of the gun. Finding it so badly 

 damaged, the trial was discontinued." The results with a 32-pounder 

 were nearly as unsatisfactory, no increase in the accuracy of fire being 

 obtained. 



Experiments witli Rifled Small Arms. A series of valuable experi- 

 ments with rifled small arms have lately been conducted by the Ord- 

 nance Committee of the British Government. Rifles of different 

 calibers and systems of rifling were tested. As it regards the effect of 

 the number of grooves in the Enfield rifle, it was found that five were 

 better than three -- the friction in loading and firing being less and the 

 shooting more accurate with the five grooves. To test the effect of 

 the pitch in rifling, two Enfield rifles were tested, the one having a 

 revolution in sixty-three inches and the other m forty-eight inches, but 

 both of uniform twist. In calm weather the slow pitch of sixty-three 

 inches was equal to the other at ranges up to 1,000 yards, but beyond 

 this it was not so accurate; and in windy weather the more rapid 

 twist was uniformly more effective at all ranges, but the barrel fouled 

 more rapidly with the residue of the powder. The caliber of these 

 rifles is 0.577 of an inch, and they were tried against a Lancaster rifle 

 of 0.55 inch caliber, elliptical bore, the twist commencing with one 

 revolution in 36 inches at the breech, increasing to one turn in 33 

 inches at the muzzle. At all ranges beyond 500 yards the Lancaster 

 rifle surpassed the Enfield in accuracy, and it^was not so liable to foul. 



