8 Lieut. Col. Miller’s description of a percussion shell , 
Having, as I conceived, conclusively ascertained by experi- 
ment, that the spiral motion may be communicated to a 
grooved cylindrical ball fired from a plain barrel, it occurred 
to me, that by the help of this principle, shells might be so 
constructed as to explode by percussion. The plan I have 
adopted for this purpose will easily be understood by an exa- 
mination of Plate I. fig. 3. A round peg is placed in the apex 
of the cone, working in a cylinder, and a pellet of percussion 
powder is placed under the peg, and over the vent which 
communicates with the cavity of the shell. By this means, 
as soon as the point of the peg strikes against any hard sub- 
stance, it slides in and ignites the percussion powder, which 
instantly communicates with the bursting charge. The cross 
pin is employed merely by way of precaution, and is removed 
as soon as the shell is put into the muzzle of the gun, which 
is then rammed home with a hollow-headed ramrod. 
The first four shells of this construction which were tried, 
were made partly of iron, but principally of wood, and fired 
from a 24 pounder against one of the bastions of Kinsale fort, 
at somewhat more than 100 yards. All of them exploded 
upon coming in contact with the fort, the splinters flying to 
a great height in the air. One exploded against a rock at the 
distance of about 200 yards, and several, fired at a longer 
range, missed the object. Experiments were afterwards made 
with iron shells, fired from a 6 pounder, and the first were 
by no means successful. The shells were cast a great deal 
too thin, so that a considerable proportion of them exploded 
in the gun, and we did not succeed once in hitting a target at 
240 yards. It may here be noticed as a circumstance well 
known, that shells are apt to explode in firing, either from 
