CAPTAIN NOBLE AND MR. E. A. ABEL ON EIRED GUNPOWDER. 
117 
Table XII. — Giving data obtained with chronoscope for calculating the velocity and 
pressure in the bore of a 10-inch 18-ton gun. Charge 60 lb. (27*2 kilos.) E. L. G. 
Weight of projectile 300 lb. (136*05 kilos.). 
Distance from base of 
shot. 
Time observed 
at plugs. 
Total time from 
seat of shot. 
Time taken by 
shot to traverse 
distance between 
plugs. 
Mean velocity over spaces 
between plugs. 
feet. 
0-00 
0-06 
0-26 
0- 46 
0-66 
0-86 
1- 06 
1-46 
1-86 
metres. 
0-000 
0-018 
0-079 
0-140 
0-201 
0-262 
0-323 
0-445 
0-567 
seconds. 
•000000 
•000596 
•001007 
•001323 
•001601 
•001856 
•002325 
■002755 
seconds. 
•000000 
•000767 
•001363 
•001774 
•002090 
•002368 
•002623 
•003092 
•003522 
seconds. 
•000767 
•000596 
•000411 
•000316 
•000278 
•000255 
•000469 
•000430 
feet per 
second. 
78-2 
336 
488 
633 
719 
781 
855 
935 
metres per 
second. 
23-8 
102-4 
148-7 
192-9 
219-1 
238-0 
260-6 
285-0 
From these data, in the same manner as in the case of pebble powder, are calculated 
the velocities and pressures exhibited in Table XIII. (p. 118). 
The velocity and pressure obtained with the E. L. G. powder are graphically repre- 
sented by the dotted curves in Plate 19 ; and by comparing these with the similar curves 
furnished by pebble powder, the advantages obtained by the use of the slow-burning 
pebble powder are clearly seen. 
Thus it will be observed that the muzzle-velocity obtained with the pebble powder 
is 1530 feet (466*3 metres), while the maximum pressure in the bore is 18 tons per 
square inch (2745 atmospheres). The velocity given by the E. L. G. powder is, on the 
other hand, only 1480 feet (451*1 metres), while the maximum pressure is 22*07 tons 
per square inch (3360 atmospheres). 
If, as in the case of pebble powder, we express for the first instants of motion the 
relation between s and t by an equation of the form of that given in (9), we obtain 
$ 57837f 42802 - ■° 2336< +‘ ooirnof 2 (i4)« 
and the values of s, v, T corresponding to those of t are given in the scheme shown in 
Table XIV. 
* In this equation and Table XIY. the unit of time is, for convenience, the one ten-thousandth part of a 
second. 
