The Sun.
London, England, 1861-11-21 00:00:00

£28,518,29D1
BANKING DEPARTMENT.

Proprietors' Capi-
tal £14,553,000
Rest
Public Deposits (in-
cluding Exche-
quer, Savings'
Banks, Commis-
missioners of Na-
tional Debt, and
Dividend Ac-

Government Secu-
rities ((including
DeadWeightAn-
nuity) £10,701,646
Other Securities 16,294,532
Notes
Gold and Silver
Coin

845,297

counts) 4,104.001
Other Deposita 13,270,27
Seven Day and
other Bills

775,390

£35,881,615

£35,881,615
,RSHALL, Chief Cashier.

M.
Dated November 21, 1861.

THE OCTAVIA. STEAMSHIP.

One of the most important screw trials which have
taken place for some time in her Majesty's navy
took place at Portsmouth yesterday, being the offi-
cial trial of the Octavia, 51, screw. The ship was
built some years since at Pembroke, from the de-
signs of Sir William Symonds, the then Surveyor
of the Navy, as a sailing frigate, but has never yet
been placed in commission. In 1860 she was placed
in dock at Portsmouth for conversion to a screw
frigate, and was taken out of dock on completion of
her conversion in the early part of this year. Her
alterations of form consequent on conversion were
cutting in two parts and lengthening amidships,
and an alteration to her stern to adapt it for the
propeller. The bow was untouched, and it there-
fore retains its original bluff form, which was one
of the most marked characteristics of the ships de-
signed by Sir William. The importance attiched
to her official trial yesterday was owing to the fact
of her being the first completed of three vessels the
machinery of which had been made with a view to
special results, in accordance with orders from the
Admiralty to that effect. The machinery of these
vessels—the Constance, Arethusa, and Octavia—was
contracted for by the firms of Messrs. Penn and Son,
Randolph and Elder, and Maudslay, Sons, and
Field, who competed to produce each a pair of en-
gines, without limit to cost of manufacture or of
design, that should be, as far as they could produce
them, economical in their working, each to be of
500-horse power, nominal. The Octavia's engines
have been designed, and their principle patented,
by Mr. Sells, chief draughtsman to Messrs. Mends-
lay, Sons, and Field, and consist of three cylinders
with surface condensers, the latter having upwards
of 11 miles length of pipes, and two air-pumps. The
cylinders are 66in. in diameter, with a 3ft. Gin.
stroke. The three cranks, in lieu of the usual two,
impart a more equable motion to the shaft by di-
viding the circle of its revolutions into three equal
parts instead of two, as heretofore. Tho cylinders
are surrounded by " water-jackets," and are thus
completely encased in steam, being the first screw
engines that have been so fitted in her Majesty's
navy, although the same principle was applied sus-
cessfully to a paddle-steamer many years ago. The
boilers are tubular, and as nearly as possible two-
thirds the size of others of the same power of engine
in other ships. From trials already made it. has
been satisfactorily proved that the consumption of
coal in working the Octavia's engines will not ex-
ceed one-half that consumed in ordinary instances.
The boilers are fitted with Mr. Field's patent super-
heating apparatus, which yesterday worked exceed-
ingly well, giving a temperature at the engine of
320 deg. It is eased on one side with a water space
into which the feed water is pumped before passing
into the boiler for the purpose of raising its tem-
perature. The steam, after passing through the
engines, is thrown by the air-pumps into a tank in
the form of distilled water, in which state it re-enters
the boilers by a pipe from the tank. The length of
the engine-room is 27ft. Gin., and that of the stock-
hole only 26 feet, one boiler only being on
each side. This great economy of boiler space
enables the ship to carry a greater quantity of
fuel, and yet it must be remembered that the
ship yesterday was doing work with these two
boilers equal to what she would have done with
double her present boiler power had she been
fitted in the ordinary way. The ship's steam
and vacuum gauges were the patent of S. Smith,
of Nottingham. The performance of the machinery
throughout the trial was most satisfactory, and was
really surprising even to those accustomed to the
working of marine engines, from its extraordinary
equability and smoothness of movement. The ship
left Portsmouth harbour soon after 10 a.m. in charge
of Mr. Jones, Government pilot, and commanded
by Cant U. Broadhead, the noting of the perform-
ance of machinery, &c., being under the supervision
of Mr. G. Murdoch, inspector of machinery afloat,
and Mr. Miller, second chief of the Steam Factory
Department. The morning was bright and fine,
but with a breeze of wind of quite the force of 4
from west. The following are the results of the six
runs made at the mile with full power :
First Run—Time, 4 min. 29 sec.; speed in knots,
13.383 ; pressure of steam, 201 b. ; revolution of engines, 68.
Second Run—Time, 5 min. 30 sec. ; speed in knots,
10.909 ; 1 ressure of steam, 201 lb.; revolution of engines, 70.
Third Run—Time, 4 min. 24 sec. ; speed in knots,
13'636 ; pressure of steam, 201 b. ; revolutions of engines, 70.
Fourth Run—Time, 6 min. 32 sec. ; speed in knots,
10.843 ; pi ensure of steam, 2010. ; revolutions of engines, 70.
Fifth Run—Time, 4 min. 23 sec. ; speed in knots,
13.688 ; pressure of steam, 201 b. ; revolutions of engines, 70.
Sixt%. Run—Time, 5 min. 29 sec. ; speed in knots,
10.942 ; pressure of steam, 201 b. ; revolutions of engines, 71.
The vacuum was the same in ail the runs-2811b.
Foar runs were next made at half power (ono boiler), with
the following results :
First Run—Time, 6 min. 11 sec. ; speed in knots,
11.576; revolutions of engines, 56.
Second Run—Time, 6 min. 29 sec. ; speed in knots,
9'254; revolutions of engines, 56.
Third Run—Time, 5 min. 31 sec. ; speed in knots,
10.256 ; revolutions of engines, 54.
Fourth Run—Time, 6 min. 37 sec. ; speed in knots,
9.068 ; revolutions of engines, 50.
The mean of the six runs (full power) was 12.255 knots,
and the mean of the four (half power) was as nearly as
possible 10 knots. The temperature of both engine-room
and stokehole was of an unusually cool character, as the
following figures will prove :

At 11.30 a.m.—Engines working up to full power. Engine
room platform, 61 deg. ; stokehole—centre, 68 ; forward,
55; aft, 58i,

At 1 p.m.—Engine room, 58 deg. ; stokehole—centro, 80
forward, 65 ; aft, 68.

At 2 p.m.—Engine room, 54 deg. ; stokehole—centre, 80
forward, 65; aft, 69.

At 2.c0 p.m., at half power.—engine room, 51 deg.;
stokehole—centre, 75; forward, 62; aft, 61.
The trial may be looked upon as most satisfactory.
To ascertain, however, the full value of the improve-
ments, the Octavia, as soon as ready for a cruise,