SHOUT NOTES ON PROFESSIONAL SUBJECTS. 
137 
another position of the plumb line. In this manner the table may be completely 
filled up for the whole extent of the range of the ordnance in position. 
The advantages gained by enabling any gunner who can read to ascertain by 
simple inspection exactly how to lay his gun at any particular moment are self- 
evident ; and even in the case of the plumb-line happening to fall between two 
rows of figures it will not require much intelligence to enable him to obtain a 
correct result, by striking, as it were, a mean between the two adjacent figures, 
84. Piling of Shot and Shell. Elongated Projectiles. Com¬ 
municated by Captain R. O’Hara, It,A. 
Eormula recommended :— 
Let B = number in breadth of pile; 
L = number in length u 
s = ^GB + 1). 
85. Picric Powder. —The Chemist, War Department, 18. 7. 70, after pro¬ 
secuting experiments with a view to providing an explosive agent as a material for 
charging shells, in continuation of those carried on by the late Ordnance Select 
Committee (see Minute 26,361, Extracts from Keportsand Proceedings of Ordnance 
Select Committee, Vol. VI. p. 488), has succeeded in producing an explosive agent 
(or mixture) which, though not so violent in its action as gun-cotton, nitro-glycerine, 
or picrate of potash powders, is a much more powerful explosive agent than gun¬ 
powder, and has other properties which appear to render it peculiarly adapted for 
employment in shells. 
This explosive agent, to which he gives the name of “picric” powder, is readily 
and expeditiously prepared, and it may be pressed and granulated without diffi¬ 
culty. It is particularly remarkable for its safety, as compared with all other 
explosive agents; it is, in fact, somewhat less sensitive to ignition by percussion 
than gunpowder. 
He suggests that the Committee on Explosives be instructed to report upon the 
merits of this explosive agent, and its fitness for service purposes. 
Director of Artillery, 19. 7. 70, forwards to President of Committee on Explo¬ 
sives for early consideration and report. 
President, 22. 7. 70, thinks the “ picric” powder well worthy of further experi¬ 
ments, and will demand some of this material (100 lbs.) for preliminary trial in 
twenty 40-pr. shells issued on Demand No. 5913, for a similar purpose, to ascer¬ 
tain, in the first instance, whether the loaded shell will sustain the explosion of the 
firing charge, 
