upon Gun-powder , &c. 305 
jriven fpace than of government powder, which is formed more 
loofely, and of various and of very irregular figures. 
Now the common price of double proof battle powder, as 
it is fold by the wholefide dealers in that commodity, is at the 
rate of £■ per cwt. net, which is juft two ftiillings by the 
pound ; while government powder is fold at^ft. 5 5 s * hun- 
dred, or one fliilling and _%-th of a penny per pound ; but bat- 
tle powder is better than government powder only in the pro- 
portion of 1,2036 to 1, or of one ftiilling and two pence to 
one ftiilling and T %fii of a penny ; battle powder is therefore 
fold at the rate of ten pence by the pound, or 4 i f per cent . 
dearer than it ought to be ; or thofe, who make ufe of it in pre- 
ference to government powder, do it at a certain lofs of 41 1- 
per cent .. of the money that the powder cofts them.. 
Qf the relation of the- velocities' of bullets to their weights. 
According to Mr. robins’s theory, when bullets of the fame 
diameter, but different weights, are difcharged from the fame 
piece by the fame quantity of powder, their velocities fhould be 
in the reciprocal fub-duplicate ratio of their weights ; but as 
this theory is founded upon a fuppofttion that the action of the 
elaftic fluid, generated from the powder, is always the fame in 
any and every given part of the bore when the charge is the 
fame, whatever may be the weight of the bullet ; and as no 
allowance is made for the expenditure of force required to put' 
the fluid itfelf in motion, or for the lofs of it by the vent ; it is 
plain that the theory is defective. - It 1 is true, Dr. hutton in his 
experiments found this law to obtain without any great error, , 
and poftibly it may hold good with fufficient accuracy in many 
cafes ; for it fometimes happens that a number of errors or 
actions* 
