108 ANNUAL OF SCIENTIFIC DISCOVERY. 



were composed of 2 2-inch layers of wrought iron enclosing a 

 3-inch layer of steel. 



CHILLED SHOT. 



The English are now making shot and shell of Bessemer steel 

 for rifled cannon of 9-inch bore. The shot are solid, cylindrical, 

 flat-fronted projectiles, and are slightly tapered at the fore end. 

 They are 14 inches long, and are fitted at the back with a disc of 

 soft brass (containing a preponderance of copper), which is in- 

 tended for filling the rifling of the gun by expansion. The brass 

 disc has at its back a projecting rim of about three-sixteenths 

 of an inch thickness, and an equal depth, which forms an expand- 

 ing cap, the sides of this cap being driven out laterally and forced 

 into the grooves of the gun by the explosion of the powder. The 

 pressure of the gases in the chamber of the gun is also made use 

 of to secure the disc to the shot. The base of the latter is pro- 

 vided with 12 radial grooves, the segments between these forming 

 inclined planes. The brass is forced into these grooves by the ex- 

 plosion, and is firmly combined with the shot itself. The shells 

 are of similar shape to the shot, but are bored out of solid 

 Bessemer steel cylinders, and fitted with cast-iron hemispherical 

 fronts. The workmanship of these projectiles is very fine ; and 

 each of them is carefulty packed in a separate wooden case for 

 transport. A considerable number of chills for casting Palliser shot 

 are also in course of manufacture at the abo\e works, to the 

 orders of the British government. They are made of soft gray 

 cast iron, and have a pair of trunnions cast on them, so that they 

 have the appearance of small mortars. The trunnions are care- 

 fully turned, and then made use of for fixing the chill to the face- 

 plate of the lathe in temporary bearings for boring. The pointed 

 bottom of the bore, corresponding to the nose of the Palliser shot, 

 is finished with a tool carefully ground to a template from a flat 

 piece of steel, this tool being inserted in the front of the boring bar, 

 and held fast in its position by a pair of screws. Great numbers 

 of such chills are in request, as they are rapidly destroyed in the 

 casting of chilled shot. 



AMERICAN GUNS IN ENGLAND. 



The American 15-inch smooth-bore cannon has been amply 

 tested in actual warfare, and is doubtless the most effective 

 weapon known in modern warfare. 



The English government have been experimenting with a 15- 

 inch Rodman, cast by Cyrus Alger, at South Boston, and its 

 performances have awakened considerable interest. The gun 

 weighs 19 tons ; with it was sent a quantity of our mammoth 

 cannon powder and a number of the spherical shells. The Lon- 

 don "Standard" has a report of the trials as follows: "The pro- 

 gramme of Thursday's trials was with the object of testing the 

 range, accuracy, and general working of the piece, and the 

 velocity of the missiles when propelled by 35 pounds, 50 pounds, 

 and 60 pounds of the American powder, and corresponding 



