THE ROYAL ARTILLERY INSTITUTION. 
221 
the muzzle of the piece. The soil was so soft that most of the shells pene¬ 
trated to great depths. 
No. 1 was found entire at 6 ft. 6 ins. 
No. 2 was not found on digging down 12 ft., and could not be felt with a 
9 ft. probe. 
No. 3 was not found on digging down 18 ft., and could not then be felt 
with the 9 ft. probe. 
No. 4 was found broken into 44 pieces, one of them only 5 ft. 9 ins. from 
the surface, but the great bulk of it at a depth of 14 ft. 6 ins. 
No. 14 was not found on digging 20 ft. Sin., but was thought to be felt 
with a 9 ft. probe. 
No. 15 was found at a perpendicular depth of 19 ft. 4 ins., giving a 
penetration of 28 ft. No others were found, and the Commanding Engineer, 
Colonel Walpole, estimated that they had buried themselves fully 30 ft. It 
would have cost about £21 each to recover them, and there they remain, to 
astonish, perhaps, geologists hereafter. The angles 6 entered in the table 
were determined approximately by the apparent inclination of the passage 
made by the shell. 
25. I do not attempt to base any conclusion on the lateral deviations of 
the shells recorded, as the mortar was imperfectly sighted, and the means of 
preserving uniformity of direction were also imperfect. If we refer the 
seventeen observed ranges—rejecting the first and last (vide Plate)—to a 
mean curve drawn through them on a large scale, their mean difference of 
range is ± 36 yds., for a mean range of 1808 yds. This is a considerable 
degree of regularity for single shells. 
26. An attempt was made by Professor, now Sir Charles Wheatstone—* 
at that time a member of the Ordnance Select Committee—to determine the 
initial velocity of some of the shells fired on the 18th December, 1857, with 
an electro-magnetic chronoscope of his own invention; and although the 
results were not entirely satisfactory, they deserve the fullest record, as the 
first application of electric agency to this purpose on any practice ground 
in England. The apparatus consisted of a delicate clock motion of BreguePs 
carrying two hands, which were started and stopped by the breaking in suc¬ 
cession of two circuits produced by induction coils. The start was given by 
the shell displacing an iron rod placed across the mouth of the mortar. This 
was effected when the shell had travelled about 4 ft. The second was effected 
by a key acted upon by the tension of a cord of 100 ft., attached to the shell. 
The arrangement failed in rounds 8 to 10 (Table I.), in consequence of the 
cord snapping; it succeeded in rounds 12 and 13, which gave respectively 
Round. Seconds. 
12 . 0-266 
13 . 0-277 
for the time occupied by the shell in travelling 100 ft., and gave as the 
mean velocity at a point about 50 ft. from the muzzle— 
Round. 
12 .. 
13 .. 
Feet. 
376 
410 
