Vermont telegraph. [volume] (Brandon [Vt.]) 1828-1843, 1838-07-25
MISCELLANEOUS.
THE GREAT WESTERN.

We find in the Frederick Herald the
interesting detailed desert ption
Of the machinery of the Great Western,
by one of the gentlemen who went out
and returned in her. As the residence of
Lieutenant William F. Lynch, Of the
United States navy, is in the neighbour
hood of Frederick, we presume we are
safe in assuming that he is the author of !
and prosperous article which |
we subjoin.-N. YSpec.
The Great Western steam ship" is
worked by a pair Of low-pressure engines,
constructed similarly to most engines used
in British steam navigation. The great
distinguishing feature of such engines is,
that the whole of tina machinery is under
deck, although the cylinders are worked
vertically.
The beam of the engine is not placed
above the cylinder, as in our boats, but a
pail of beams are placed below the cyin
der, and answers the same purpose, at the
same time that they bring great portion
of the machinery below the water line,
and do not hamper the d, ok. The stroke
OF such engines is shortened, though not
necessarily, by this arrangement, and in
the "Great Western" it is onIy seven feet.
The two engines are connected to the
main shaft on which the paddles are fixed,
and in case Of an accident TO one engine,
the other continues to work both paddles
or wheels, by disconnecting the connect
ing rod Of the deranged engine This
was the case in the outward voyage, when
one engine propelled the Great Western
during thIrty-four hours, at the rate of 81
knots per hour.
These engines are 200 horse power;
they are worked by steam not exceeding
81 lbs per square inch, An apparatus
for reducing the steam by expansion is
attached, but rare y used.
There are four boilers, each lOd feet
long, 81 feet wide, and Is high. There
are three fire places to each floor, which
terminate in fue that runs through the
boiler, an extent of about rs feet, before
it passes into the smoke funnel.
These four boilers are connected by
valves to one general steam pipe, which
supplies the two engines. Any one boil
er can be shut off at pleasure, and as three
boilers with little extra fuel can raise
sufficient steam, the fourth can be cleansed
out whenever required The four boilers
are more than sufficient for the work, and
consume very little more coal than three
at the same time the fiemen are not hur-
ried, and the doors of the furnaces are
repeatedly thrown upon to keep down the
steam.
The consumption Of coal, both on the
outward and homeward passage to the
United States, did not exceed 81 lbs. per
} horse power per hour. In the roug hest
part of the homeward trip, when the ship
was week out Of port, and in better trim
from having consumed a considerable o.
coal, the consumption was As per hour
The Inconvenience TO which steam boilers
have been heretofore subjected, by the
deposition of salt and other earthly mat
tiers, was obviated on board of this ship
by peculiar arrangement, the invention
) of Messrs. Maudsley, Sons & Field.
, In marine steam boilers, it is usual &c
blow off portion Of the densest salt water
from the bottom Of the boiler, by means
f Of a pipe or blow off cock. In this man
ner, a portion Of the strongest brine is
forced out-but the quantity is limited and
, much fuel wasted by the loss of heat.
On board Of the Great Western brass
, plunger pump is attacked to the bottom O
, each boiler and draws off constant stream
: of brine, the loss Of which is supplied by
pipe conveying hot water from the res
ervoir--which, pouring into the boiler
| keeps up a constant current, thereby pre-
= venting deposition and subsequent con
: cretion.
Supposing the density of the water O
5 the ocean to be 100, and that deposition
S cannot take place, in other words, that the
water would hold the salt and other earthly
r matters in solution, until its density is
reduced to 663, the density Of the watal
|, in the boilers of the G. W. was rarel,
less than go. AT the expiration of eact
: trip, the boilers were as clean as if frest
= water had been used. To ascertain the
r proper quantity to be drawn off, and t.
f regulate the pumps accordingly, the den
l., sity Of the brine is ascertained by letting
S portion of it cool and 1ryin g it with !;
b hydrometer. This simple substitute fo
> the old plan of blowing off has proved *
: efficient that it will no doubt be generally
e adopted. ...
: The boilers of the G. Western are o
e wrought iron, square. with ! wagon tops
s The maximum pressure is % lbs. to tn,
l. square inch. The moment that the pres
e sure of steam exceeds that amount, tn,
e; safety valve rises and the surplus steam
/ passes through the. safety pipe, to tb,
!, upper air. From their shape and size
D those boilers could withstand a pressur,
t of lbs. to the square inch-and if the,
$ were to burst with that pressure, only
E those in the engine and Ere rooms woult
o j snffsr-tha nassannnrs al tsh;a : L