The weekly pioneer and Democrat. [volume] (Saint Paul, Minn. Territory) 1855-1865, 1862-02-28

strength of the vessed, so as to bear the re.
coil of the mortar. The design is apparen-
tly perfect"
| THE MORTARs
The twenty heavy mortars which form
the principal armament of the fleet were
cast at Pittsburgh, and are of immense size
and strength. Their average weight is
over seventeen thousand pounds, or eight
and half tons-almost equal to the
weight of the ten inch columbiads, which
are nearly three times the length of the
mortars. The diameter of the bore is
thirteen inches. The total depth of the
bore is thirty-fve inches-a little more than
two and half times it's diameter. But
the most remarkable feature in their con-
struction is the thickness OF the metal
around the bore, which is at every point no
less than fifteen inches. The trunions
measure fifteen inches 10 diameter. The
entire length of the mortar is fifty-inches,
and the aggregate diameter forty. three
inches, or more than three and half feet.
Commodore Porter's mortars are eleva-
ted or depressed by means of cog like pro-
Jections on the breech, into which a lever
hts, supported by the framework of the
carriage. BY means of the accura te work
Ing OF the revolving platform and carriage
ranges can easily be obtained. 1t is believ.
ed that accurate firing may be made at the
distance of two and quarter miles.
The force of the recoll of these mortars,
when the fall charge of powder is allowed
fourteen pounds), is stated to be seventy.
five tons.
THE BOMBS AND POWDER.
The bombshels to be thrown from the
mortars are OF the ordinary description, re-
sembng round shot, but hollow, and weigh.
ing untitled over two hundred pounds each,
the most formidable ordnance missiles
known III modern warfare, with the single
exception OF those used in the Rodman co
lumoiad OF fifteen inch bore. Between
seven and eight thousand of these bombs
have been furnished Tor the fotia, and it is
understood that the amount of eXplos i've
material contained in each shell exceeds
twelve pounds the powder having been
Carefully granulated expressly for this
purpose.
The tusos by which the moment of ex-
piosion is regulated are Of several kinds
var!ou3ly denominated conclusive. percus.
sive. and time fuses. The object of the
two former is TO cause the shslI to burst
Immediately on striking the object at which
1t is aimed; OF the last to cause it to burst
after q certain time, determined by the
length OF the burning composition with
which the fuse is filed. The conclusive
fuse is furnished with al internal mechan
ism SO adjusted that, though it resist the
shock of firing, or even that of slight
Craze, it will yield to the shock ofimpact--
the conclusion shaking the burning compo-
sition into the loaded cavity of the shell
and producing the explosion The percus-
sion fuse, like the cap used for firing pis-
tolls or muskets, is instantly gnited by the
mere force OF contact with any object
against which the shell may happen to
strike. Besides shell, missiles called car
casses are sometimes fired from mortars.
They differ from shells only that, instead of
powder, they are filed with an infamable
composition, which speedily produces an
almost inextinguishable coDhagration when
thrown amongst combustible materials.
The effect of the firing cannot at present
&c accurately estimated. The extraordina
ry weight and strength of the mortar the
charge OF powder (unprecedentediy large in
practice) the long raDge and high velocity
OF the projectiles, and their terribly destruc,
tive character, combine to render the expes
dition one of the most important that has
been undertaken during the war
DIMENSIONS AND WEIGHT OF HEAVY MoRTARs.
A 13-lnch sea mortar weighs lin round
numoers) 1000 pounds ; Its bed over
5000 pounds more. 1t is about four feet
two inches in length, and will Qoaded with
twenty pounds OF powder) throw a shell of
1877 pounds nearly 4,500 yards i21a mies)
or carcass OF 2l2 pounds about as far.
4 l0-inch mortar OF the same class weighs
close upon 600 pounds, and its bed 5000
pounds. 1t will throw a shell of eighty
seven pounds 1000 yards In Captain
Porter's fleet there are twenty of these Is
inch mOftars, besides others of inferior
calibre, the first serious experiments with
which the rebels will soon have an opportu-
nifty OF witnessing. There are these advan~
tages il very big shells: With only enough
powder to explode them, they burst into a
larger number of fragments than smaller
shells, whilst, with full charge of powder
their superior weight sinks them deeply
enough in the earth, Or through the arched
ways OF Notifications, to make them act in
the most devastating manner as mine.