THE EOYAL AI1TILLEBY INSTITUTION, 
35 
To simplify matters and render the effects clearer, we will, in the first 
instance, suppose the practice to take place over smooth water, and with a 
light wind blowing across the range. 
A certain time, say four seconds after firing, a faint cloud of smoke appears 
over, in front of, or behind the target, indicating the point of rupture of the 
shell, i.e. where the action of case shot commences. Tig. 8. 
These are not hypothetical cases, they have occurred thousands of times, 
and will occur doubtless again when this nature of ammunition is used. 
There are then three points for observation; first, the point of rupture, 
second, the line of foam or spray, third, the target. 
A close observation will shew that the figure of the foam is oval. 
We will select some examples; (1) the smoke above the target, the foam 
just on this side of it, Tig. 4. By reducing elevation and fuze we may 
Fig. 4. 
see the smoke lower down on the target, and the white line of foam 
[vol. v.] 5 
