required in the development of the full force of the
explosive. Gen. Abbot's results for intensity of action per unit of
weight of the most important substances is as follows:

Blasting gelatine........................... 142
Forcite " ........................... 133
Dynamite No. 1.............................. 100
Gun-cotton, wet............................. 87
Nitro-glycerine............................. 81
Gunpowder.............................. 20 to 50

Col. Bucknill, of the Royal Engineers, in his publication of 1888,
gives the following:

Blasting gelatine........................... 142
Forcite " ........................... 133
Dynamite No. 1.............................. 100
Gun-cotton, dry............................. 100
" " ............................. 80
Gunpowder................................... 25

In both tables dynamite No. 1 is assumed as the standard of
comparison. Col. Bucknill states that his gun-cotton results differ
from Gen. Abbot's, because he experimented with much larger
quantities, viz., 500-pound charges. Gen. Abbot's experiments led him
to believe that an instantaneous mean pressure of 6,500 pounds per
square inch would give a fatal blow to the double bottom of a modern
armorclad, and he developed a formula which gives this blow with
blasting gelatine at the following distances under water, viz.:

Pounds.
At 5 feet.................................. 4
" 10 " .................................. 17
" 20 " .................................. 67
" 30 " .................................. 160
" 40 " .................................. 311

Col. Bucknill's experiments caused him to believe that a pressure of
12,000 pounds per square inch is required, and his formula, which is
somewhat different from Abbot's, gives widely different results at
close quarters, but they approach each other as the distance
increases.

His results are as follows:
Pounds.
At 5 feet................................ 231/2
" 10 " ................................ 75
" 20 " ................................ 177
" 30 " ................................ 274
" 40 " ................................ 369

Regarding the comparative effects of gunpowder and the high
explosives, I think Gen. Abbot's estimate of a varying value for
powd