The Portland daily press., 1895-07-13

economy, and in the other case tbe en-.
glhe is working at only 1-5 its actual
power. AS the power required to drive
! a fessei varies as the cube of the speed
sn', siie coal burned per knot will vary as the
square of the speed, or in other words,
With two engines of equal economy, one
OF Which would drive the boat I'd knots
and the other s knots per hour. the first
Would burn 100 tons of coal in going the
same distance as the other one Would run
| in burning "a tons. This illustrates the
advantage OF having engines which are
economical at slow speed. This was the
principal reason why low-poWered ma
chinery was put in these ships
These boats will require at 10 knots
their maximum speed, 800 indicated
horsepower, at 10 knots 45O indicated
! horsepower, and at s knots 25O indi-
Gated horse-pow The capacity of the
bunkers will be about 25O tons. The coal
consumption for all purposes at full pow
er will be about % tons per day, giving a
steaming radius in smooth water of 8, $50
knots. At 10 knots the coal consumption
will be about IL tons per day and the
steaIning radius will be about 5, 600 knots.
AT 6 knots speed the coal consumption
would be about 81 tons per day, and the
steaming radius will be about 5, $50 miles,
making it possible to run them at that
speed from San Francisco to New Zea-
land
The steaming radius of small ships is
greatly affected by the wind and weather
The large Atlantic liners plough through
all kinds of weather and only the hardest
storms affect their speed, and then only
to a limited extent These boats when
steaming against moderate hard wind
and sea will have their speed decreased
two or three knots. The single screw
boat will be affected much more in this
respect than the other fone since her
spars and rigging will catch more wind.
She will also be troubled more by her en-
g1nes racing, since her screw will not be
SO deeply immersed as that of her rival.
The great gain in the twin-screw ship
Will be the ease with which she can steam
IN and out of harbors and up narrow,
crooked rivers, owing to the greater ease
and safety with which twin-screw ships
can be steered. But the sailing type can
reel off or knots an hour Indefinitely
on long cruises at no cost for fuel, and
for months at a time in active service can
be totally independent of coaling STA
tions.
The single-screw boat will be lighted
by electricity, and provided with steam
steerer and steam windlass; space and
weight are allowed for these features in
the twin-screw boats, but their installa-
tion will depend entirely upon their pos
slb1l1ty within the price limit of $3.50, 000
The armaments, being identical in both
types. will consist of six 4-inch, four
6-pounders, and two 1-pounders guns, all
rapid fire, and will be disposed in this
order: Four 4-inch guns in two batteries,
port and starboard, on the gun-deck mid
ships, the two other 4-inch guns being
carried on the main deck, one at the bow
and one at the stern, each having wide
arc of fire The 6-pounder guns will be
carried on the gun deck, two well for
ward, one at either bow, and two mid
ships between the 4-inch guns, respec-
lively in the port and starboard batteries.
The 1.pounder gun will be disposed
where most advantageous on the ham
mock larthing.
For the finch guns there will be 800
rounds of ammunition; for the 6-pound-
ers there will be 1000 rounds of ammuni-
tion; and for 1-pounder 1883 rounds of
ammunition. The character of their ser
vice for which these gunboats are partic-
ularly designed requires that they be ex-
of the major parts of the battery by an
unbroken dock, besides adding materially
to the stiffness and strength of the vessels
gives admirable protection to the guns
crew in action. This necessarily expos ed
position of the bow and the stern guns
is justified only by their arc of fire and
possible usefulness in running action;
WIll6 lOI ElNoE SorNlCe, lOf WHICH UQeSG
boats are particularly fitted, the disposi-
tion of the gun-deck battery is all that
could be desired.
Each of the vessels will carry about ten
officers, 1875 enlisted men, and small
guard of marines, numbering perhaps 10
men The vessels are SO commodious,
however, that for special duty very
much larger complement could be accom-
modated, or large number of refugees
could be taken aboard
Secretary Herbert, who is compelled by
law to have two of these vessels built on
the Pacific coast. two on the Atlantic and
two on the Gulf if possible, has invited
bids under two heads: Those based upon
the plans and specifications Of the Navy
Department, and those based upon the de-
signs and plans of the contractors; and
not more than two of the gunboats to be
built by one contracting party.
The framing of each of the boats accord
ing to the specifications will be of steel
from the keel up to and above the water
line; the upper edge of the wood plank
will lap the top side plating about 8 feet
Planks of Georgia pine will be worked
on the frames, secured thereto by by COM
vent galvanic action. The outside sur
face of the plank will be coppered
No plating will be worked on the under
water body of the vessel, except the keel
plates, strip of plating on each side of
keel plates under the boilers to form the
lower portion of a water tank and narrow
strips for the plates under the longitude
nails and bilge keels. The entire top sides
will be plated as on steel vessels.
Throughout the machinery space an in
ner bottom of plating will be worked, |
giving added strength to this part of the
vessel, enabling the bilges to be kept clean
and affording additional means of safety |
should sthe outer bottom be ruptured