The Sun.
London, England, 1869-12-07 00:00:00

NAVAL AND MILI7ARY IN2ELLIGENCE.

Telegrams received from Alexandria state that
her Majesty's Indian troopship Serapis left that port
for Portsmouth on the 4th inst., all well ; and that
the Crocodile arrived there from Portsmouth on the
sth inst., all well.
By the courtesy of Capt. the Hon. A. A. Coch-
rane, C. 8., superintendent, and other chief officials
of Sheerness dockyard, our correspondent is enabled
to send us the results of the competitive trials on
board her Majesty's corvette Druid, 1,322 tons, to
ascertain the relative merits of the Griffiths'
(Maudslay and Co.) propeller, as against those of
Vansittart, or Lowe's blades. As the ultimat deci-
sion is a matter of the highest importance, we give
the comparative results, as to speed, wear and tear,
mean revolution, and consumption of coal, &c., is
detail. The trial of the Griffiths-Maudslay propel-
ler was made on the 2ith Nov. last, and iu that re-
port some of the trials were given, but in order that
our nautical anl scientific readers may clearly
understand the difference between the working of
the two propellers we give the details concerning
each. The mean revolutions of the shaft per mile,
at full-bciler power, was, with the Griffiths-
Maudslay, on the day just named, 452, the figures
for six runs ranging from 307 to 515 ; the mean of
revolutions per minute was 96.80 ; the range of
the figures for the same number of
.runs being from
98.51 to 95.80 ; the time of the mile run ranged
from 4tnin. 3sec. to smin. 20sec. ; the mean of speed
being 12.986 ; ranging, as worked out, from
11.250 knots to 13.075. These results were ob-
tained, as we have before reported, at an expen-
diture of coal, and with such an amount of oscilla-
tion and vibration—from 7 to 8 by index--as
would lead to a cost in money utterly incommen-
surate, and which would therefore lead to a loss of
very serious amount in the course of each twelve-
month's steaming. These defects were removed
in the Vansittart trial, which, at full-boiler power,
on Thursday last, showed the following re-
sults :—The mean of revolutions of shaft per mile,
for six runs, was from 382 to 535, averag-
ing 453.6 ; the mean of revolutions per mi-
nute was, for six runs, 96.61, ranging from
95.53 to 96.98 ; the time of each mile ranged from
3 min. 57 sec. to 5 min. 36 sec. ; the mean of speed
being 12 861, ranging, as worked out, from 10.714
knots to 15.190 knots. These results were obtained
at a much less expenditure of coal, and with the
most satisfactory diminution of vibration and oscil-
lation, this ranging from 4 to 5 by index, as against
7to 8 with the Griffiths-Maudslay. The half-
boiler traffic of Vansittart's propeller were equally
satisfactory, and these results were commented on
with some astonishment by the officials on board,
among whom were the Hon. Captain Cochrane,
C. 8., Mr. J. Steele, Admiralty inspector of steam
machinery afloat (who was sent from Whitehall ex-
pressly for this trial), Mr. Warrener, of the firm of
Maudslay, Sons, and Field (who supplied the boilers
and machinery), &c. As regards the Vansittart
blades this may be regarded as being only a pre-
liminary trial, the Admiralty having issued a
peremptory order that, if necessary, the Vansit-
tart may have two more runs with the screw
at a different angle of pitch : the Griffiths
Maudslay pitch having been 15ft. 2in., against
13ft. 3iin. of the Vansittart. The Vansittart blades
were fitted to the Maudslay " boss," although' by
preference the boss for the blades should be of a
spherical form, which gives greater scope to the
curves, which are carried from the point of the front
edges of the blades close into the boss on the oppo-
site face of each blade. A curved line can also be
seen on the front edges of the blade, the curves
playing an important part by preventing that in-
jurious vibration of the ship to which we have before
alluded. They also have the long-sought-for effect
of keeping the ship steady at the highest rate of
speed. Still speaking of the Vansittart, it may be
added, that in consepuence of the duration of a fog
which obscured the Maplin-mile beacons, the ad-
vantage of making the runs at full-boiler power at
high tide, when the surface of the water was
smooth, was lost, and the runs had to be taken on
a strong ebb tile, which is not favourable for
realizing a high rate of speed. The wind, too, which
had lifted the fog, also began to rise, and it was the
opinion of many on board that had two extra runs
been taken in lieu of the two first ones a much
higher result would have been obtained, as the
fires were drawing well and there was a plentiful
supply of steam, which, in consequence of wait-
ing for the fog to lift, had gone down a little. Time,
however, did not allow of this being done. Thera
can be no doubt that the problem as regards the
iteration of the ship, and its consequent discom-
fort to the crew and loss of money in repairs to the
country, has at length been solved by Mrs. Van-
sittart's improvements upon her father's, the late
Mr. Lowe's, inventions ; and as our ships are now
engined with an amount of power which renders
them susceptible of vibration and oscillation, care
should be taken to provide them with screw pro-
pellers free from this defect. That this has now
been accomplished by the " Lowe-Vausittart" pro-
peller is proved beyond all doubt, for the indicated
horse-power with the last-named screw was 2,141,
while with the Griffiths-Maudslay it was not less
than 2,374 horses, giving a difference of 233 horses
in favour of the Vansittart, while as high, if not
higher, average of speed was obtained. Another
great advantage gained by the Vansittart propeller
over its competitors is the extraordinary backing
power which it gives. The vessel having been
brought to a standstill, steam was put on to one-
third only, when the ship went astern in a manner
that was never before witnessed. The circles,
too, at full and half boiler power, were made
with the utmost facility ; in fact, with the
Vansittart propeller the ship gave twice the
helm she did with the Griffiths. The pendulum at
half-boiler power with the Vansittart showed an
oscillation of only 0 to 1, while with the Griffiths it
reached 5 to 6, as much as with the first named at
full boiler power. All these results prove that
greater economy, as well as comfort of the crew,
combined with as high a rate of speed, is obtained
with the Vansittart as compared with the Griffiths,
and this is a truth that cannot be too strongly im-
pressed OR those members of the Government to
whom the management of our naval affairs has been
intrusted.

With reference to the paragraph which appeared
on Friday last as to the gunvessel Teazer, appointed
to take the place of the unfortunate Thistle, our
correspondent at Sheerness assures that no repairs
of importance were effected on board the Teazer at
that dockyard. The facts are these :—The Teazer
was ordered from Portsmouth to Sheerness to take
on board the officers and crew of the Thistle, and
that was all. Any defect, either of hull or machiney,
should have been detected at Portsmouth for why
the officials at that dockyard should have sent a de-
fective ship to Sheerness, to receive on board a crew
intended for a foreign station, it is hard to imagine,
although the explanation would be welcomed by the
nation at large.
A circular has been issued by direction of the
Field-Marshal Commanding-in-Chief relative to
the custom of certain tradesmen, especially tailors,
to give credit for goods supplied and even to lend
money to gentlemen cadets at the Royal Military
Academy at Woolwich, and the Royal Military
College at Sandhurst. The order points out the
evil =sequences of these practices, and requests
the parents and guardians of gentlemen cadets at
Woolwich not to pay any debt contracted by a cadet
without their sanction, or any running account
beyond a stated limit of amount fixed by them.
It became known at Chatham yesterday that the
finding and sentence of the general court-martial
that assembled at that garrison a short time back,
for the trial of Lieut. George Frederick Henry Rule,
of the Chatham Voilgon of Royal Marines, and
formerly of the Woolwich Division, had been n 1);,
proved by the Queen. The charge upon which
Lieutenant Rule was brought to trial was for st-Z-
-dalous conduct in having appropriated to his own
use the sum of £75 that had been intrusted to him
by Private Francis Rowsell, of the Plymouth Divi-
sion, to be deposited in the Post-office Savings-
bank, Lieut. Rule having been in command of the
detachment of Royal Marines that was doing duty
on board the Octavia, 35, and to which the man
Rowsell was attached. The Court found the pri-
§oner guilty, and acatence4 him to be cashiered.