Gunnenj : — Expenments at Woolwich. 235 



being 6 feet. The timber rests upon an iron plate of an inch and 

 a quarter thick, and the whole is held together by strong vertical 

 cheeks of gun- metal and the requisite screws and bolts. The 

 materials of the pendulum are so disposed as to bring the centre 

 oi gravilji about 11 feet, and the centre of oscillation about 12 

 feet, below the axis of rotation ; and to allow the point of im- 

 pact of the ball upon the face of the pendulum to occupy any as- 

 signed place between those two centres. This pendulum, which 

 was constructed under the direction of Colonel Millar of the royal 

 artillery, has its frame-work mortised into a permanent edifice ; 

 and is so admirablv framed and so exquisitely suspended, as to 

 produce an extraordinary union of freedom and steadiness of 

 motion with stability of structure. Such is the firmness of the 

 construction, that the shock not merely of 6-pound balls, but 

 even of 24-pouud balls, moving with a velocity of 1300 feet per 

 second, caused no prejudicial strain in the framing, nor even pro- 

 duced the slightest perceptible sinuosity in the groove described 

 by the stylette on the broad indicatory arch below the pendulum. 

 And at the same time, such was the freedom of suspension, that 

 the slightest breeze moved this imoiense mass; and that in every 

 case when the experiment was tried, it required more than 60 

 oscillations to reduce the semi-arc vi vibration from 7'^ to 6". 



By the construction of a ballistic pendulum of sufficient magni- 

 tude to sustain without derangement the shock of large balls mov- 

 ing with great rapidity, an important point is gained ; since the 

 velocities with which balls move when propelled from the heavier 

 artillery will no longer remain a matter of mere induction, but a 

 fair result of actual experiment. The velocities of balls fired 

 from 12-, 18-, and even 24-pounders can now be readily and Sa- 

 tisfactorily deduced from the motion communicated to the oscil- 

 lating block by the several balls. In the experiments already 

 made by means of this new pendulum, only 6-pounder3 and 24- 

 pounders have been employed ; the intermediate sizes being left 

 for subsequent experience. What has been done, however, fully 

 confirms the experiments of Dr. Hutton as to the law between the 

 charges and the velocities, and as to the increased initial velocity 

 occasioned by an additional length of bore. In a variety of 

 rounds, both with different charges and with guns of different 

 lengths, there was not a single deviation from either of these laws ; 

 nor was there a single case in which stronger powder, as indicated 

 by an accurate cjirouvette, did not furnish the predicted result. 



Other ai)paratus, we are told, is constructing for the purpose 

 of confirming or modifying the old results, and of extending the 

 inquiry to many points hitherto untouched. 



STEAM 



