72 
Inches, 
Outer diameter of the fhell 12.8 
Inner, or diameter of the 
cavity - - SPE 
Thicknefs of metal at the 
fuze-hole - - = 45 
Ditto at the bottom or op- 
pofitepart - - - 2.2 
Diameter of the fuze-hole ‘1.7 
‘And the dimenfions: are fimilar in 
the other fhells. The fuze-hole is 
conical, the oppofite fides of which, 
when produced, meet at the extre- 
mity of the diameter, which pafles 
through the middle of the hole. 
He found, that the iron plug could 
hardly ever be driven fo firmly into 
the firze-hole as to refift the force 
of the expanfion of the ice, which 
ANNUAL REGISTER, 1790, 
pufhed it out with great velocity, — 
and a bolt or cylinder of ice, of a- 
confiderable length, immediately - 
fhot up from the hole. But when 
the plug was fixed in with fprings, 
which laid hold of the infide of the 
cavity, fo that the plug could not 
poflibly be pufhed out, the force of 
expantion then fplit the fhell, and a 
fin or plate of ice fhot out quite 
around, © atig 3 
Extrad from Major Williams’s Letter, 
Thefe experiments were made on 
iron-fhells, from the 13 inch thel] 
to the cochorn, of 4.4 inches dia- 
meter, by filling the fhell nearly 
with water, and driving in am iron 
plug with a fledge hammer, 
nate Therm Be the iad Diftance. 
Degt er. | oe 00 "go 35 ' Unknown. 
PAS — 43 go 37-25 22 feet. 
23. | — 16 go 34.5 Unknown. 
24. — 6 80 39.25 62 
LT mcd tT 9 45 39-25 387 
1785. 
Jan. 2. | — 19 45 4L.75 41S 
4. — 12 45 42 Burft. 
9 mao tare 45 40.5 325 
REMARKS, 
Dec, 21.—The fuze-axis of the 
fhell lay nearly perpendicular to the 
horizon. On examining the effect, 
about 9 o’clock the following day, I 
obferved the plug gone, and a cy- 
linder of ice, of 4% inches high, 
rifing perpendicularly from the fuze- 
hole, and of equal diameter. © I 
tearched carefully for the plug, but 
could not find it, as there was about 
3% feet of {now on the ground. 
Dec. 22.—I watched this fhell 
about an hour, when, being called 
out on bufinefs, I found, on my re- 
turn, three hours after, the plug 
gone, and the icy cylinder 22 inches 
high. Plug loft. 
23-—I had a plug made, and 
jagged or notched along the fides, 
to prévent its being forced out 0 
: eafily 5 
