MECHANICS AND USEFUL ARTS. 95 



The following are some of the most noticeable improvements which have 

 been made public : A patent has been obtained by Captain Blakely, of the 

 Royal Artillery, England, for making cannon as follows: He takes a tube 

 of cast steel, and then surrounds tin's with external rings of wrought iron 

 shrunk on. He also employs a buffer or spring of air at the butt of mortars to 

 moderate their recoil. He also claims the method of strengthening old guns, 

 by shrinking wrought iron bands on them. 



New War Projectile. The London Times describes a new war projectile, the 

 invention of Captain Disney, which has been tried with success. It consists in 

 fitting shells with a bursting charge of powder contained in a metal cylin- 

 der, and filling the rest of then- space with a highly combustible fluid, which 

 upon exposure to the air ignites every tiling with which it is brought hi con- 

 tact. This fluid does not act upon the substance of the shell, is not in itself 

 explosive, and being prevented from leaking by a nicely fitted brass mouth 

 plug, enables the missile to be carried about without much risk. 



Aiming with Cannon. Captain Davison of England has patented the appli- 

 cation to cannon of a telescopic sight and cross-wires, or micrometer so that 

 by means of them and a coUimator, the piece of ordnance may be brought into 

 its proper position by day or night, after every discharge, without the necessity 

 of observing the object aimed at, after the proper range and aim have been 

 first obtained. 



The attention of scientific men in France and England has been called of 

 late to a valuable improvement in artillery, said to have been introduced by 

 Colonel Cavalli, of the Sardinian army. This gun is double-grooved, giving 

 about a three-quarter turn to the projectile, which is of an oblong form, of 

 cast-iron, pointed at the top, convex toward the powder, and having two ribs 

 running lengthwise, to correspond with the grooves in the gun. The London 

 Times' correspondent remarks with regard to it : 



" As regards the principle of grooved barrels and ribbed projectiles, there 

 seems no objection to apply the system to guns now in use; for the difficulties 

 once made as to the wearing out of these grooves are practically disproved by 

 guns and projectiles now in the arsenal of Turin, which have been used scores 

 of times, and without any obvious deterioration. But this principle Colonel 

 Cavalli had combined with that of loading at the breach, and when he tried a 

 gun of this kind in England, hi 1850, before some distinguished officers of 

 artillery (and which gun had been cast at Stockholm), it unfortunately burst, 

 and there was consequently an unjust prejudice, perhaps, created again-st it. 

 Even then the fault of the bursting was acknowledged to be hi the material 

 and not in the principle, and the official returns of the practice with guns of 

 smooth bore on that occasion are highly confirmatory of the merits of grooves. 

 Since then he has made some further improvements hi the method of securing 

 the breech after loading, and, with a gun weighing 66 cwt, loaded with 6 Ib. 

 10 oz. of powder and a projectile of 66 Ibs., the folio whig results have been 

 arrived at : 



"With ten degrees of elevation, at a distance of 3,068 yards English, there 

 was a lateral deviation of 3 yards and a longitudinal one of 40 ; with an 

 elevation of fifteen degrees, and at 4,142 yards' distance, the lateral deviation 



