1 6 Lieut. Col. Miller’s description of a percussion shell , 
Length 
6,24 inches. 
Diameter 
4,16 
Length of sides 
- 4,16 
Height of cone 
2,08 
Depth of grooves 
0,2 
Width of ditto round 
the circumference 0,8 
Length of peg 
1,4 
Diameter of ditto 
0,4 
Diameter of vent 
0,15 
Thickness of sides 
0,85 
Thickness of bottom 
- 0,74 
Diameter of chamber 
2,46 
Height of ditto 
3,42 
Windage 
0,04 
In all the experiments already made, it has been observed 
that the line of fire is generally good, but that the shells 
which have missed the object, went almost invariably either 
too high or too low, which is exactly the result we might 
from theory expect, when their ends are not perfectly 
balanced. The method of proving whether their ends be 
exactly balanced, is by floating them in mercury, their spe- 
cific gravity when filled being something less than half that 
of mercury. When properly balanced, they float horizon- 
tally, and the balance is not perfect until that is effected. 
It is conceived that shells of this description might be used 
against towns and stockades, for battering in breach, and also 
in the field ; but it is evidently in naval warfare that they 
would be most efficient, for the burning of shipping. That 
for a 24 pounder will weigh 3olbs. and contain 2 fibs, of 
powder, or what is reckoned better, powder and combustible 
