The Sun.
London, England, 1863-08-26 00:00:00

TRIAL TRIP OF THE AURORA.

Since 1840-1, when the screw may be considered
to have been definitely adopted in this country for
both the Royal and mercantile navies, there has
been no incident connected with its subsequent his-
tory which has created so great a degree of interest
in the minds of scientific men and the effieers of
both services as the introduction of the double, or
" twin" screw principle, each screw worked by in-
dependent engine power. The reason of this is suffi-
ciently obvious to the initiated, although perhaps
not to the general public. The fact is, we are enor-
mously increasing the tonnage of our ships and
their engine power, and, as a natural sequence to
this course, the draught of water of these large
vessels has to be increased in proportion to
their tonnage, in order to fully develope their
screw's power, for, as the engine power
is increased so also increases the diameter
of the screw, and so also must increase in
the same ratio the ship's draught of water. The
natural result of this general increase in size and
driving power is that the deep-loaded merchant
single-screw steamer can only move in certain direc-
tions in narrow and tortuous rivers, and conse-
quently incurs a considerable degree of extra ex-
pense under such circumstances, exclusive of loss of
time, which in the present day is acknowledged to
be of more real value than Money itself. Our War-
rior and Black Prince are, and our Minotaur and
Northumberland will be, from their great draught
of water and the great space they require to
turn in, perfectly useless to attack such for-
tresses as Cronstad t, New York, or even Cher-
bourg; or to run into such a place as Spithead,
passing the proposed marine forts on the Noman and
Horse, and tackle a ship or two inside the forts.
The use of a single screw is, in fact, attended
with so many dangers and difficulties, which may
possibly be avoided by the use of two screws
both in the Royal and mercantile marine, that it
cart be no matter of wonder that the subject should
have acquired a degree of importance second only
to the universal adoption of the screw itself in pre-
ference to the paddle. The practical introduction
of the " twin" screw principle in this country is
owing to the enterprise of Messrs. J. and W.
Dudgeon, shipbuilders and engineers, of Limehouse,
who, in November last, tried their first vessel fitted
in this way on the Thames, the Flora, of 400 tons
and 130 horse power of engines (collectively), fol-
lowed after wards by two other vessels, the Hebe and
Kate, of about the same dimensions and power, the
trials of which were carried out under the supervision
of Admiralty officials, and were fully reported on each
occasion in The Sun. The success of the trials
were in each instance most unequivocal and satisfac-
tory, and in yesterday's trial of the Aurora, while
the value of the twin screw principle was again de-
monstrated in the most satisfactory manner possible,
it was also on this occasion developed more fully
than in either of the previous trials. The double
screw was adopted by the Admiralty some years
since in the construction of the iron-cased floating
batteries, but they were driven in those vessels by
collective, not independent engine power ; conse-
quently the adoption of the principle in their case
only enable the Admiralty to construct vessels that
float at a moderately light draught of water, and
carry an immense (for their tonnage) weight of
armour and armament, in addition to the weight of
their engines, but it gave the vessels no increased
powers of turning, or man ceuvring rapidly under
steam in any circumscribed space, which they would
have possessed had their screws been driven by in-
dependent engines, as were the Aurora's in yester-
day's trial. It is these increased facilities which
the double independent screws offer to ships
of war for manoeuvring rapidly, whether engaged
with an enemy afloat or with a shore battery, that
has brought the subject so prominently before the
notice of the Admiralty and the general public,
and to these military purposes our report of yester-
day's trial more especially refers.
The Aurora is an iron vessel, 165 ft. in length,
with a beam of 23ft., a depth of 13ft. Gin., an area
of midahip section of 150 square feet, and a dis-
placement of 400 tons. Her engines have a collec-
tive nominal power of 120 horse, and drive two
three-bladed screws, each independently of the
other, 7ft. in diameter, and with a pitch of 14ft. 6in.
The cylinders have a diameter of 26in., and a 21in.
stroke. The Aurora is a smart looking vessel, with
much finer lines forward and aft than were pos-
sessed by either of her predecessors. She carries
two short masts, rigged for fore and aft canvas, and
altogether, although "light as a bladder" on the
water, has the appearance of a thorough steam
" clipper." Her draught of water at starting yes-
terday was 7ft. 3in. aft, and sft. 3in. forward.
A large party of gentlemen left town yesterday
morning by the 10.52 train from Fenchurch-street
tor Tilbury station pier. alongside winch the Aurora
lay with her steam up. Immediately on the party
embarking the screws were set to work in opposite
directions, and the vessel slowed round with her
head down river and started on her trial at
12.20 p.m., under the charge of Mr. Leigh,
Trinity pilot, the wind being strong at S.W., and
the tide at half ebb. In running past the mea-
sured mile, in the Lower Hope, with the engines
not up in the number of their revolutions, she was
timed and found to go over the ground in 4 min.
8 sec., giving the vessel a speed of 14.516 knots.
At 1.30 p.m. the Aurora was approaching the
Nore Light vessel, the engines averaging 120 revo-
lutions, with 271 b. of steam and a vacuum of 25in.,
and every part working with the greatest possible
smoothness. At 137 the Nore was passed, the dis-
tance from Tilbury, 20 nautical miles, having been
done in 1 hour and 17 minutes, an almost unparal-
leled rate of speed, considering the vessel's horse
power of engine and hull displacement. From the
Nore to the Mouse Light the vessel continued her
course, the wind still fresh from the same quarter,
and the movement of the water which necessarily
accompanied it giving the vessel, from her light
draught and hold upon the water, sufficient " roll"
to detract from the efficient acting of her only just
submerged screws. Notwithstanding this disad-
vantage, however, she ran past the " mile" on
the Maplin Sands in 4 minutes 10 seconds, giv-
ing a speed of 14.400 knots, it being now about
sleek water, and the tide of little moment
either way, and accomplished the distance
to the Mouse Light at 2h. sm. 225., hav-
ing been 28 minutes and 23 seconds from the Nore
—eight nautical miles. During the latter part of
the run down a small jib had been set to steady the
vessel, but no other help was given by the vessel's
canvas to her engines in attaining this somewhat
extraordinary rate of speed. From the Mouse the
Aurora was run out between the Maplin and the
Barrow as far as the Swin Light, passing the James
Dixon, a fine screw collier under sail and full steam,
with her head in the same direction as the Aurora's
on the way. On reaching the Swin the vessel's bead
wasbrought round and laid homeward, it having
been
decided not to lengthen the trial by making' circles,
&c, owing to the high state of the wind. the light con-
dition of the vessel, and the very
satisfactory manner
in which she had already turned both to port andstar-
board in answer to her rudder or screws, proving that
Hebe, and Kate, a asawere possessed by the Flora,
hi
ch, must necessarily
she possessed the same facilities in that respec
in
fact,et builtw .or and fitted with
lity of manoeuvring,
he possessed by every vessel
pissed at 411. 15m,, and about two
Soot bend was pa,
double screws driven by indepudent engine,.
mike ahead was been the Sea Swallow, one of the
fastest paddle steamers on the Thames, Plying be-
tween the Arora eventually ass-
London, Southend, and Sheerness, and a hot
as
yr
at 4h.d 40m. in the midst of a heavy
squall of wind and rain, and subsequently during
the run up to Blackwell
ienhgtehneaetq naturally
passing everything under
steam she came across. Gravesend was passed at
5h.15m., the engines making on the average at the
time 1'.27 e. B;A:;kw,-,11 pier, thf:. cloeing

world.
The principle of the adaptation of double screws
to ships of war has been so far acknowledged in its
importance by the Admiralty that their lordships
have given Messrs. Dudgeon an order to construct
a small vessel which shall combine in their most
efficient form the double-screw principle which they
have so spiritedly and successfully brought into
public notice.

Naval and Military Intelligence.

THE NAVY.

The iron troopship Tamar, 2,812 tons, 500 horse
power, since her removal from Chatham harbour to
the steam basin, has been inspected by Capt. W. R.
Mends, C. 8., director of the transport department
of the navy, who was accompanied by Capt. C. Wise,
superintendent of the dockyard, and Mr. W. Moody,
master shipwright. The result of the inspreion
was in the highest degree satisfactory, and the
manner in which the Tamar has been constructed
and fitted, reflects great credit on her builders,
Messrs. Samuda Brothers. All the available hands
belonging to the dockyard are at present engaged
in preparing the vessel for sea, and already her
lower masts have been put in, and a commencement
has been made in fitting her wire standing rigging•
In consequence of the great length of the Tamar,
some difficulty was experienced in turning her when
placed in the great basin, the size of which is 520 ft.
by 300 ft., and it was found necessary to open the
gates of No. 1 dock to allow the ship's head to get
clear. As soon, however, as the large basins now
in progress at Chatham Dockyard are completed,
not the slightest difficulty will be experienced in
turning vessels of double the size of the Tamar.
During the time the vessel was in dock at Chatham
she was fitted with a couple of steam cranes in the
forecastle for hoisting in and out stores, baggage,
&c. In addition to the poop and topgallant fore-
castle, with which she has been fitted since her
launch, she is to have cabinserected for her warrant
officers, she will also be supplied with an improved
oven for baking fresh bread for the use of the troops
and ship's company on a plan invented by Mr.
Blake, of Portsmouth dockyard. The cabin for the
officers of the ship under a lofty poop, and the quar-
ters for the ship's company are placed beneath the
topgallant forecastle, by which arrangement all
communication is cut elf between the troops and the
ship's company.
The Clio, 22, 1,472 tons, 400 horse power, Capt.
T. Milles, is being rapidly dismantled at the Nore,
previously to her being paid off into the Chatham
steam reserve. She has been in commission up-
wards of four years, during which time she has been
attached to the Pacific station. The Clio has been
lan exceedingly healthy ship, and only a compara-
tively small portion of her crew who left England
in her in 1859 have been sent home es invalids,
while desertions have been very few. Most of her
stores have been returned to the dockyard, and her
guns and shot forwarded to the Ordnance stores,
Chatham ; her powder:and shell have been deposited
in the magazines at Upnor Castle.
The ships on the Australian station at the date of
the last advices were the Harrier, 17, Capt. Sulli.
van, at New Zealand; the Miranda, 14, Capt. Jere
kins, at Sydney ; the Eclipse, 4, Commander Mayne,
at New Zealand. The Miranda has been under-
going repair in the Government dry dock at Syd-
ney, dry rot having penetrated the hull in so many
places that it was found necessary to lay both sides
open. Several portions of the frame have been taken
out and replaced by colonial timber of excellent
quality.
Her Majesty's steam storeship Supply, Master-
Commander Bawden, from the Mediterranean, has
been docked at WoolWich for survey and repair.
Her masts have been taken out and tested in the
usual manner by scraping, straining, and baring, to
ascertain their efficiency for farther service, and
have been found defective. The mainmast has been
in place since 1849, in constant use, and the fore-
mast was heel-pieced in Malta dockyard two years
ago. The yards and topmasts are still serviceable
and good. The lower masts will now be replaced
by spars of more substantial dimensions, suitable to
the burden of the ship, with new rigging, &c. The
tunnel to the screw alley, hitherto dangerous, on ac-
count of its confined size, will be enlarged, and the
ship will be entirely refitted throughout. Peacock's
composition, which has been found to answer the
purpose of preserving the ship's bottom, is in
course of being removed, and the ship will be paid
down anew with the same process.
Mr. Reed's experimental iron-cased sloop Enter-
prise, built at Deptford, is now receiving her armour
casing, which is bent in Woolwich dockyard and
forwarded to the ship, ready to be applied. Two
of the plates, am. by 4ft. 9in. each, have been
fitted to the sides in an admirable and most success-
ful manner, and two
others are ready to be for-
warded. The whole of the plates will be supplied
of Sheffield, who made
by Mr. Brown, a large pro-
portion of those used in the Caledonia.
The paddlewheel steam storeship Dee, with vic-
tualling and other stores, left Plymouth Sound on
for Ilawlbowline.
Monday evening
The screw steam gunboat Goshawk (tender to the
Majestic), having been repaired at Davenport, was
placed yesterday alongside the gunwharf to receive
artillery.
A naval court-martial assembled yesterday on
board the Formidable, 84, Captain J.
R
Pafford, flag-
ship of Vice-Admiral of the Red, Sir G. R. Lam-
bert, K.C.8., Commander-in-Chief at the Nore, for
the trial of Private James Hennessey, Royal Ma-
tines, serving on board her gejesty's gunboat Mag.
net, tender to the Pembroke, 60, on a charge of
having absented himself from his post when on
sentry on board the said vessel, on the Gth August
last, and remaining absent from the said ship until.and also for making away with
the following day'
certain of his
divisional necessaries. Capt. J. Fut-
and Lieut.-Commander C. G. Fegan,
ford presided,
of the Magnet, prosecuted. Mr. Knight, solicitor,
Rochester, officiated as Deputy Judge-Advocate, and
conducted the case. The prisoner, who pleaded
guilty, and threw himself on the mercy of the court,
was sentenced to nine months' imprisonment with
hard labour in the prison a of Lewes, and to forfeit two
days' pay. The court afterwards proceeded with
the trial of Private Thomas Pratt, Royal Marines,
serving gunboat, on a charge
on board the Magnet
of having absented himself from the said ship, and
also with making away with his divisional neces-
saries. The prisoner, who made no defence, was
sentenced to three months' imprisonment with hard
labour, and 21 days' solitary confinement, and also
to forfeit two days' pay.
Capt. the Hon. G. D. Keane, who has recently
returned fram the command of the Charybdis, 21,
400-horse power, in the Pacific, has been appointed
to the command of the naval barracks at Sheerness,
and has taken up
his appointment, which, it is ru-
moured, he will retain for a short time.
Ono of the old anchors, of which a cargo was
brought home a few days ago from Antigua in the
Betsy Hall, was yesterday tested by the hydraulic
machinery at Woolwich, with a view of appropriat-
ing these in the best state of preservation to the
purposes of harbour moorings. Many of the an-
chors are supposed to have been forged upwards of
2jo Mars lip, awl t.re much corroded. The one