The Sun.
London, England, 1861-05-21 00:00:00

THE _MONSTER AMERICAN 15-INCH CANXO2V:

The new principle of casting large guns—hollow instead
of solid—by means of a current of water introduced into the
core which forms the mould of the bore, thus cooling from
interior, has been successfully applied to the manufacture
of a monster cannon at the Fort Fitt Foundry, Pittsburg,
in the United States. A new era in the casting of iron
cannon has commenced; and we now proceed to describe
the last great practical result of this new and highly inge-
nious process. The monster gun, better perhaps known by
the name of the 1.5-inch gun, has the following dimensions
Its total length is 15 feet 10 inches; greater exterior dia-
meter 4 feet across the breech, fining down to 25 inches at
the muzzle, The thickness of metal behind the ellip-
soidal chamber is 25 inches, and 161 inches at the junction.
of the bore with the chamber, fining down to 5 inches at,
the muzzle. The weight of this piece of ordnance is nearly
22 tons. The solid 68 pounder, the heaviest cast-iron gun of'
our own service, weighs about 4 tons 15 cwt. The 15-inch
gun is mounted at Fort Monroe upon an iron centre-pintle
carriage; running up and recoiling in the usual manner;
and fires shells of two classes. The first, to be used where
the greatest possible explosive effect is wanted, of the mini-
mum thickness (`2l inches) admissible to endure the shock
of the charge, is about 3051 b weight, containing about 181 b. of
powder. The second, for battering purposes, has El wall of
5 inches thickness, .and weighs 4101 b. There is also a solid
shot of the enormous weight of 4251 b, but for the reasons
already mentioned connected with solid castings of large
masses, it is very doubtful if it is practicable to cast a satis-
factory solid shot of this diameter. The windage allowed is
one-tenth of an inch. Major Barnard, of the American En-
gineers, who has published an account of this cannon, gives
us the following summary of the practice carried on with it
in the experimental trials. In five trials, at 2,000 yards, with
351 b of powder, the lateral deviations were confined within
five yards on either side of the target. The vertical devia-
tions, probably due to varying initial velocities, or perhaps
to some difference in the weight of the shells, ranged 17
yards each way short and over. With 401 b. of large
grained powder, the initial velocity was found to be 1,328
feet per second. The greatest range attained, with maxi-
mum elevation of 28 deg. 35 min., was 5,730 yards, with a
time of flight of 27 :eeconds. Such immense charges, how-
ever, produce far less strain on the gun than might be sup-
posed, owing to the :nature of the powder used, and described
in the official reports as "large grained," and as " Rodman's
perforated cake powder." It will be interesting at this
point to notice the performance of the English monster
gun, better known as. the Horsfall gun, mounted near South-
sea Castle, Portsmouth; this being the largest piece of
ordnance hitherto made in this country. The weight of
this gun is about 2 tons, and it throws a solid shot of
about 3601b5. weight ; 130 rounds have been fired, with
charges of 401 b. and 501 b. of powder; and with 18 deg. of
elevation a range of little over 5,000 yards was obtained.
But that the cann on was unable to stand these proof
charges, eomparativ cly moderate for its calibre, was known
to Le strongly suspeeted by the Director-General of Artil-
lery, and this °pink) n_ was confirmed by the discovery of a
crack of over three inches in length in the chamber, when
searched and examined lately by Captain Freeth, assistant
inspector of artillery. It is probable that it will be again
subjected to proof at an early date. The American 15-inch
cannon had, up to the, date of the latest reports, fired 350
rounds with full charges; and at the 330th round, when
the last search was made, the most delicate tests applied to
the bOre failed to indicate the slightest enlargement or de-
terioration of any kincl,.—Army end Navy Gazette.

COUNTRY MARKETS.

COLCHESTER,. MAy 18.

A good supply of wlwat, for which the trade was rather
slow, at prices the turn lower. Barley saleable at prices
much the same as of late. Beans were rather dearer.
Peas scarcely a sample.
Wheat, white 6os to 66s Beans, Mazagan..36; to 425
red 44s to 60s I Middle & small 42s to 48s
Barley —s to —s I White peas 44.. to 48s
Oats ..--s to —s Grey.. 385 to 44s