The Sun.
London, England, 1864-12-10 00:00:00

Naval and Military Intelligence.

Her Majesty's screw steamer Cadmus, 21, 1,466
tons, 400 horse power, having undergone extensive
alteration and repair, both to hull and machinery,
was yesterday taken out of Chatham harbour to the
measured mile at the Maplin Sands, near the Nore,
for the purpose of testing her steaming qualities,
her former trials having proved unsatisfactory. The
Cadmus was built at Chatham dockyard, and, after
seeing a lengthened period of service, underwent a
thorough repair at their establishment, where she
was fitted with a topgallant forecastle. Her engines
are of 400 horse power (nominal); and were menu•
factured by Messrs. Penn and Sons, Greenwich.
The cylinders are each sft 4in in diameter, and the
length of stroke is 31t 3in. The foar boilers are fed
by 16 furnaces. Since the Cadmus has been in the
hands of the shipwright and engineer department
at Chatham she has been fitted with a "left-handed"
Griffiths screw, in lieu of her former Admiralty
propeller, in consequence of the unsatisfactory ree
sults obtained from the latter. The screw weighs
rather lees than ten tons, and is 16ft in diameter,
with a length of blade of 3ft bin, the edge of the
blades during the trial yesterday being 3in out of
the water. The screw is set at a pitch of 24ft, but
this can be varied from 20ft to 28ft. The trial was
under the superintendence of Capt. W. K. Hall,
C. 8., commanding the steam reserve in the Med-
way, the other officials on board being Mr T. Baker,
chief inspector of machinery at Chatham dockyard,
and Mr W. Rumble, inspector of machinery afloat.
The master-shipwright's department was repre-
sented by Mr Barley. The Cadmus was navi-
gated from Chatham by Mr Blakey, Queen's
pilot, and on being placed on the trial-ground six
runs were tt..ken over the measured mile, with the
following results First run--Tinie, 4min. 57st c. ;
speed, in knots per hour, 12.121 ; number of revolu
lions, 62. Second run—Time, smin. (aim ; speed,
10.027 knots; number of revolutions, 61. Third
run—Tinat; Cnin. 53sec. ; speed, 12.5 knots;
number of revolutions, 62. Four ran—Time,
sLoin. 12scc. ; speed, 11.533 knots; number of
revolutions, 61. Fifth mi.—Time, 4 min. 34 sec. ;
speed, 13.138 knots; number of revolutions, 62.
Last run.—Time, 5 min.l6 sec. ; 5pecd,11,392 knots ;
and number of revolutions, 61. From the means of
these readings the first averages were 11.074,
11.263, 12'019, 12338, and 12265 knots, and the
second means IPI6B, 11.641, 12.178, and 12'301
knots, giving the truermean, or actual speed of the
ship, as 11.882 knots per hour. The result is cone
sidered very satiefactory. It shows that the changes
made in the Cadmus have increased her speed nearly
21 knots per hour, her average speed on the occa-
sion of her last official trial at her deep-sea draught
being only 9'709 knots per hour. Various causes are
assigned for this improvement, the chief of which
are the new eerewepropeller with which she has
been fitted, and the alterations effected in her engines.
On the former occasion of her trial it was found im-
possible to keep the steam at a greater pressure than
17.251 b, even with the throttleevalve but a quarter
open. The exit area of the stoke-hole, which in
other vessels of the corvette class amounts to 20
square inches per horse power, in the Cadmus was
only 7-10ths of a square inch, and to these great
defects the unsatisfactory results thus obtained were
attributable. Since that occasion the changes made
have been very great, and these now combine to
make the Cadmus one of the fastest of her class
of vessels in the navy. After the full-boiler
runs were completed a couple of runs were taken
at half-speed, with two of the boilers cut off,
when the mean average speed realised was 905
knots. At the termination of the speed trials
the steamer was tested in making the circles and
half-circles. When at full bailer power, with the
helm brought over hard to port, at an angle of 21
dog., the complete circle was made in 3 min. 33
sec. ; at half boiler power the full circle was made
to starboard in 5 min. 50 sec., with the helm at
an angle of 27 deg. The half circle at full power
was made to starboard in 2 min. 11 see., and to port
in 2 min. 5 sec. From the time of telegraphing the
order from the bridge to the engine-room the en-
gines were stopped dead from full speed in 15 sec.,
and started ahead in 10 sec. ; the time occupied in
starting astern after the transmission of the order
was 6 sec. The engines, which were in charge of
Mr Bird, engineer, worked with remarkable steadi-
ness and regularity, and there was a total absence
of hot bearings. The boilers emitted a full supply
of steam, and the indicator cards showed the actual
work of the engines during the trial to be 1,580-
horse power. The Cadmus is ventilated on Mr
Baker's system, which has been found to answer
well on board the Achilles, Royal Oak, and other
vessels where it has been adopted. During the trial
yesterday the temperature, which on deck was 51
deg., averaged 60 deg. in the engine-room, and 111
deg. in the stokeholes. The Cadmus has all her
guns, shot, shell, and other stores on board, and her
bunkers filled with upwards of 200 tons of coal.
At the close of the trials yesterday she brought up at
the entrance to Chatham harbour, and this morning
will steam up alongside the dockyard, where she
will await orders from the Admiralty as to her sub
aequent movements.
The Trident, paddlewheel steam sloop,Commander
C. J. Balfour, arrived at Spithead yesterday morn-
ing from the Mediterranean. After transferring
her naval and marine invalids from various ships on
the station to the flagship Victory, she left for
having been nearly four
Woolwich. to be paid off,
years in commission.
Capt. Harrison, who has been appointed Adjutant
at the Royal Engineer establishment, Chatham, has
joined headquarters and commenced the duties of
the appointment, in succession to Capt. Harvey.
The following appointments were made on Thurs-
day at the Admiralty :—Lieut. James D. Barker to
the Cumberland—Snb..Lieut. Victor E. J. B. Von
Donna the Duncan—Charles Bayfield, second
master, additional, to the Duncan—aad R. H. C.
Hebdon, second master, additional, to the Victory,
RV supernumerary.