EXPEEIMENTS ON SOLID AND GASEOUS EXPLOSIVES. 



369 



small modifications introduced in the construction of the latter instrument, though 

 they added to its reliability, are not of sufficient importance to warrant a more 

 detailed description. 



Three gauges of this pattern were in use, the first reading from 3 to 12 atmospheres, 

 the second from 12 to 50, the third from 50 to 200. 



EXPLOSION ENCLOSURE 



Fig. 7. Firing plug. 



The insulation of the central conductor is cone-shaped, to prevent its being forced out by the pressure of 

 the explosion. A small cartridge of fine gunpowder can, when required, be placed round the fine 

 wire W. The gas-tight cone joint D is protected, in the usual manner, from direct contact with the 

 flame by a projecting piece, which closely fits the aperture in the explosion chamber. 



Valves and Connections. 



The various valves by which the flow of the gas is regulated are of the type shown 

 in fig. 8. 



The gas inlet is at A, whereas B is connected to a gauge which indicates the 

 pressures behind the valve. A fine screw-thread is cut on the spindle S. By turning 

 the wheel W the conical end F of the spindle is lifted slightly from its seat and the gas 

 flows to the part of the apparatus connected to C. To avoid any sudden rush of gas 

 the spindle bears a slightly tapered prolongation, which nearly fits the outlet, and, 

 therefore, several turns of the screw are necessary to give the full opening. 



The many connections required throughout the apparatus are all cone joints of the 

 type shown at C. 



The female connection ends in a hollow cone, the angle being about 100 degrees. 

 The male D is a cylinder of brass, an inch or two long, ending in a hemisphere, which 

 is pressed into the cone by the nut N, the inner surface of which bears upon a ring K. 



VOL. ccv. A. 3 B 



