MECHANICS AND USEFUL ARTS. 89 



the extent of ordering the construction of six hundred 60-pounders, 

 is in the following words : 



" The path we must follow is clearly indicated : cast-iron cylinders, 

 hooped, a most simple manufacture, which, once established, only re- 

 quires great care in securing the proper diameter to the bore of the 

 hoops." 



The reports from which we derive our information contain detailed 

 accounts of experiments with breech-loading cannon, but of none 

 which gave satisfaction to the artillery committee. The lead-coated 

 shot they declare to be uncertain in aim, in consequence of the diffi- 

 culty of always securing exactly the same difference between its di- 

 ameter and that of the bore of the gun. 



An exceedingly interesting experiment is reported to test the pow- 

 ers of the new rifled field and siege guns. The fortress of Molina de 

 Aragon was breached in three places by an old smooth-bored 24- 

 pounder, by a 4^-inch rifled gun, and by a 3^-inch rifled gun. 

 The former opened a breach eleven yards wide, in the ten feet thick 

 wall, in one hundred and seven rounds, requiring ten. hours. The 

 second made a similar breach in two hundred and twenty-two rounds, 

 in fifteen hours ; and the third in eight hundred rounds, in forty 

 hours. 



Taking into consideration the much greater facility of moving the 

 lighter rifled guns than the heavy smooth-bore 24-pounder, the com- 

 mission unanimously recommend the use of the medium rifled gun for 

 siege purposes. 



On the Elongated Cannon Projectiles used by the U. S. Govern- 

 ment. In the present war, five varieties of elongated projectiles 

 have been used by the artillery of the United States army, viz., the 

 "James," " Hotchkiss," "Sawyer," " Parrott," and " Shinkl" shot. 

 The two first have been already noticed in previous volumes of the 

 Annual of Scientific Discovery (see vols. 1859, 1860) ; the others may 

 be briefly described as follows : 



The Sawyer Shot is of cast-iron, finished in a lathe, then coated 

 with tin to secure the adherence of a covering of lead or pewter. It 

 is then placed in a very accurate mould, and lead or pewter is cast 

 round it, forming wings, which fit and fill the grooves very nearly. 

 This shot will, of course, fit only the gun having the same number of 

 grooves, and cannot avoid windage ; while in loading it care must be 

 taken to enter the wings into the grooves of the gun. 



The Parrott Shot is cast on a shallow wrought-iron, which forms 

 the base of the missile, the action of the powder driving the edges of 

 the cup into the grooves. It may be fired from any gun except a 

 bronze one, which would not resist the wear of the wrought-iron 

 against the corners of the grooves, and even cast-iron or steel could 

 not long endure the enormous friction. 



The Shinkl Shot is a plain iron shot with oval front and conical 

 rear, on which a wad of papier mache, or similar substance, is forced 

 by the powder explosion spreading into the grooves. 



Filling Shells with Molten Iron. Further experiments have re- 

 cently been made at Woolwich, England, on the use of shells filled 

 with molten iron. A number of gun-carriages, platforms, and men 

 formed of wood, representing artillery-men, were arranged about a 



