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of a grooved ball may be sustained during its flight, or even pro- 

 duced originally by the resistance of the air acting on the inclined 

 planes formed by the grooves, on the same principle as the rotation 

 of the sails of a windmill. These considerations led the author to 

 conceive the possibility of giving the spiral motion to grooved shot 

 fired from a plain barrel ; an idea which, he remarks, seems to have 

 also occurred to Mr. Robins, who left, however, no clue to enable us 

 to discover the nature of his plan. He accordingly commenced a 

 series of experiments for the purpose, and, abandoning all idea of 

 success with spherical shot, adopted the cylindrical form. His first 

 trials were made in the summer of 1821. Hemispherical ends were 

 adapted to cylindrical shot, but abandoned, it being found desirable 

 so to dispose the weight as to give the greatest possible length to 

 the shot; grooves of various dimensions were tried, and were found 

 not to answer when narrow, but required to be wide enough to allow 

 their sides to be exposed, from one end to the other, to a current of 

 air blowing straight between them. 



In 1822, some further experiments were made at Woolwich, with 

 grooved leaden shot fired from musket barrels, and with wooden shot 

 from a 5^-inch howitzer, in which the shot, being received on tar- 

 gets, or in banks of earth, were in numerous instances found to have 

 flown in the manner expected, i. e. point foremost. Similar trials 

 with grooved leaden bullets from a plain barrel, were made in 1823, 

 to the extent of several hundreds ; and the balls, when well made, 

 were always found to fly end foremost. Large wooden grooved shot 

 were also fired from a 24-pounder, at Kinsale Fort, and on some oc- 

 casions by night with lighted fusees in their sides, by which con- 

 trivance it was distinctly seen that the spiral motion was acquired 

 and maintained steadily throughout their flight. 



Having thus proved the possibility of communicating the spiral 

 motion to a grooved shot from a plain barrel, it next occurred to the 

 author, that a shell so constructed, and flying always with one end 

 foremost, might be made to explode by percussion. This he accom- 

 plished by forming his shell into a cylinder terminated by a conical 

 apex, in which is formed a vent communicating with the cavity of 

 the shell. This vent is plugged with an iron peg, under which is 

 placed a pellet of percussion powder, and which, on the point of the 

 cone striking a hard substance, is driven in and ignites the percussion 

 powder, which immediately communicates with the bursting charge. 



Several shells of this construction were fired against Kinsale Fort 

 from a 24-pounder, and exploded on striking it ; and the author goes 

 on to describe a great variety of trials with iron shells of different 

 sizes, and fired under different circumstances, both at Kinsale Castle 

 and Leith Fort, in all of which a considerable amount of success was 

 obtained, and in some cases the explosions of the shells took place 

 on striking at 800, 850, and even 1200 yards. 



Further experiments were tried at Woolwich in 1826, on the hull 

 of a 28-gun ship, during three successive days. Out of thirty-one 

 shells fired at her, at various ranges from 330 to 450 yards, eleven 

 exploded on striking ; one of which took effect on the mainmast and 



