1870.] Engineering — Civil and Mechanical. 533 



loaders. Steel and chilled iron also appear likely again to give 

 place to bronze as a material for field guns. The arm of the day- 

 is, however, the mitrailleur, or mitrailleuse as it is sometimes called, 

 which has already performed such bloody work in the present war. 

 The mitrailleur belongs to the same class of weapon as the revolver, 

 having, however, this advantage, that its barrels may be fired almost 

 simultaneously. One of the earliest of this class of weapon was 

 the American Gatling gun, which was first seen in Europe at the 

 Exhibition of 1867. This consists of six barrels mounted in two 

 rings of iron, fixed on a central axis ; at the rear of these are two 

 half-cylinders of iron, bolted together, which serve to enclose and 

 protect the mechanism ; within these a cylinder revolves, with 

 grooves into which cartridges fall as it is turned round, and by a 

 self-acting mechanism they are pushed forward into the barrels, 

 fired, and the empty cases subsequently extracted. A continuous 

 and rapid fire can thus be maintained as long as there remains 

 ammunition at hand to continue feeding the breech. The mitrailleur 

 which has recently been subjected to comparative and experimental 

 tests at Shoeburyness, is of Belgian origin ; it was introduced into 

 this country by Major George Fosbery, Y.C., of the Bengal Staff 

 Corps. It was invented in 1867 by M. Montigny, but has received 

 several modifications and improvements since that date. This 

 weapon consists of thirty-seven steel barrels, of an hexagonal form 

 exteriorly, fitted and soldered together, and finally surrounded by a 

 wrought-iron tube. To the tube or barrel thus constituted a breech 

 attachment is screwed, and the two together, with the movable 

 breech-block and its lever, form the gun. In outward appearance 

 the gun looks like a solid steel block about four feet long, pierced 

 with thirty-seven holes. A cartridge holder, consisting of a steel 

 plate with holes corresponding in position with the barrels of the 

 gun, being filled with central-fire cartridges, is inserted in the breech- 

 piece and held in its place by suitable arrangements, whilst by the 

 movement of a handle on the right-hand side of the gun, corre- 

 sponding plungers are released, and striking their respective cart- 

 ridges fire the gun. According to the rapidity with which this handle 

 is moved the barrels may be fired one by one, or in a volley. The 

 weight of each projectile is 600 grains, and the charge 115 grains. 

 It would be premature at present to give any results of the experi- 

 ments now being carried on. It may be here stated that Major 

 Fosbery estimated the speed at which the mitrailleur could be fired 

 at ten rounds per minute, but this rate has not yet been nearly 

 attained in practice. 



Steam and Air Engines. — Although the union of steam and 

 air for the purpose of effecting economy in engine working is by no 

 means a new invention, yet the means adopted for effecting this 

 object which have recently been made public, appear to be so far 



