14 
FOREST AND STREAM. 
Jan. S, 19S .-j 
Fig J, 
2f»5 A 
ENGINES OE TOBPEDO DESTBOYEB "DABING-." 
be open to all recognized yacht clubs, and a close regatta on 
Labor Day. 
The rebuilt Ihetis, now a schooner with a modern bow, waa 
launched from Lawley's yard on Dec. 22, in the presence ol her 
owner Mr E B. Baugh, o£ Philadelphia, who has renamed her 
"MonReve" Apropos ol Thetis, the Btory of her race with a 
cutter is going the rounds of the papers in a very incorrect 
shape the 45tt. cutter Maggie being natnei as her antagonist. 
It was not Maggie, but Stranger, a mi;ch larger boat, 01 the 
same length as Thetis: alter the race at Newport for the citi- 
zens' cups, in Sept. 1886, the two started around the Cape for 
Boston not racing, but starting at the same time to make the 
passage Some very coarse weather was met with and Stranger 
hove to under ihe tape, from all accounts making bad weather 
of it, while Thetis went on her way and made her port in good 
time. 
Wadena, steam yacht, J. H. Wade, arrived at Bangkok on 
Nov. 25, with owner and family on board, and was to sail Dec. 2. 
The Christmas number of the Yachtsman this year is the reg- 
ular issue of the paper for Dec. 13, ot the usual size page, but 
containing in all "60 pages. Three colored supplements are 
given, one of the bows of Vigilant, and two of Vigilant and Bri- 
tannia. The different pages are printed in various tints which 
serve to bring out well the smaller illustrations, of which there 
are a great many. Two designs are given, one lor a 40 rater of 
67ft. l.w.l. of semi-fin type and with a most peculiar rig, the 
mast well lorward and but one headsail, tacked to the stemhead. 
The other design is lor a 2 rater with two centerplates. The 
reading matter is very good, the biography of Capt. John 
Woods, who sailed Livonia here in 1871, beiug specially inter- 
esting. 
There has been a dearth of news this week, pending the meet- 
ing of ihe Royal Yacht Squadron on Jan. 7. The present status 
of the negotiations is discussed at length on our editorial page. 
While no positive action toward builuing a Cup defender has yet 
been taken, it is certain that an order will be placed with the 
Herreshoffs as soon as a race is decided on. Mr. George Gould, 
whohasbeeu nominated for Commodore of the Atlantic Y. C, 
will bring Vigilant home it she is needed for the trial races. 
High Speed Vessels and Engines. 
A great deal has been heard at times in this country of speeds 
of 30 knots and over by various high speed crait, but so tar as 
thorough, authenticated tests go, all such claims must give way 
to the official records of the latest torpedo boat destroyers turned 
out by Messrs. J. I. Thornycroft <fc Co., of Chiswick, on the 
Thames. We are indebted to Engineering, of Nov. 2-16, lor the 
accompanying descriptions and illustrations: 
"The engines here shown possess especial interest from the 
fact that ihe Daring attained the extraordinary speed oi 29% 
knots during one run on an unofficial trial. An account ol this 
trial appeared in these columns, and it will be remembered that 
the fastest run on the mile was made against a tide whiuh, 
though slack, certainly did nothing to accelerate the speed of the 
boat between the section posts. In order to prevent misconcep- 
tion, it should be added that the vessel was not carrying her full 
load, as required by Admiraltv regulations. Nevertheless, the 
performance was an extraordinary one ; and on her contract 
trial she made a mean speed of 28.213 knots during the six runs 
on the measured mile. It may be as well to state . ere generally 
that in estimating the relative speed of vessels it is important to 
note whether the recorded rate of steaming is that attained on 
the contract or taking-over trial. 
"The engines illustrated are of the three-stage compound 
type, and have high and intermediate pressure cylinders 19in. 
and 27in. in diameter, while there are two low-pressure cylinders 
each 27in. in diameter. The stroke is 16in. The gene al di sign, 
as will be seen by our illustrations, is quite novel. The i-et of 
engines (there are two sets to each vessel, as the torpedo boat 
destroyers are twin-screw) is structurally divided in two parts, 
of which the high and intermediate cylinders form o.ie, while 
the two low-pressure cylinders form the other. This is well 
shown in Fig. 1. As will' be seen by our illustrations, the cylin- 
ders are inclined from the veriical, and this enables the engines 
to be contained in a shorter fore-and-aft space than if they were 
upright. The crankpin bearings are of the great length usual in 
fast-running engines of this type, and, the cylinders overlapping 
in the way they do, there is no room for main bearings between 
the cylinders of each pair. Each pair of cranks is therefore 
arranged in the following manner: There are two ordinary 
crank webs forged in one with the shaft in the usual manner, 
and Irom these the crankpins project. At the other end of the 
crankpins is a double web common to both crankpins, one pin 
projecting from one end of the web and the other pin from the 
other end. For purposes of description it might be said that 
there are two overhung cranks connected by an intermediate 
web. 
"The framing of the engines is no less unusual than the crank 
arrangement. In place ot the ordinary pillar standards placed 
back and front of the cylinders, there are central p, liars in pairs, 
which extend down to the main bearings, being formed, in lact, 
by a prolongation upward of the keep bolts ol these bearings. 
In this way the standards are almost directly over the crank- 
shaft, and practically in the same fore-and-aft plane as the pis- 
ton rods. They, therefore, take the thrust o£ the pistons directly, 
and it will be evident that the breastplate can ihus be very much 
lightened. There are also diagonal stays, as shown in Fig. 3. 
Between each pair of these central standards, and attached to 
them, is a strong steel casting, plainly shown in Fig. 2 The 
bottom ends of the slipper guides are bolted to this casting. 
When it is necessary to examine or remove the main bearings, 
the nuts on the combined bolt and standard eau be moved up on 
the latter, and the keeps can then be slid up, thus exposing the 
brasses. 
"In these engines a successful attempt has been made to 
arrange the moving parts so that they may counterbalance each 
other, no weights being necessary especially for balancing pur- 
poses ; naturally a point ot advautage in regard to the saving of 
weight. The cr .nks, as already stated, are arranged in pairs, 
each crank of a pair being almost opposite to its fellow. By this 
means two adjacent cynndeis have, at any given time, their 
reciprocating parts moving in opposite directions. With regard 
to fore-and-alt vibration, there is a couple tending to rotate the 
shalt in a vertical longitudinal plane round a center between 
any two adjacent crankpins, but the cranks being so close to- 
gether — having no bearing between as already described — the 
effort is so small as to be inappreciable. We have s .id that the 
cranks are almost opposite to eacu other, anu it will be seen 
that if they were diametrically opposed they would not pass the 
dead centers at the same instant, owing to the different inclina- 
tions of the cylinders. For a portion of the stroke, therefore, 
the pistons would both be moving in the same direction, and the 
engine would be unbalanced to this extent. The cranks ol each 
pair of cylinders are, therefore,set so that the angle between chein 
is 180 deg., less the angle corresponding to the inclination oi the 
cylinders irom each other, ana in this way both pistons reach 
the opposite ends of their respective strokes at the same time. 
Another useiul end attained by this arrangement of cranes is 
that the pressure on the bearings is relieved throughout the 
stroke. Were the cranks opposite, both pistons would press in 
the same direction during a part of the stroke. As a practical 
result this system ol natural balancing works out excellently. 
During the trial of the Daring, when running at full speed, 
vibration oi the boat was haroly felt, as stated fu the account of 
the trial published in our issue oi June 29 last; aaditis said that 
when the boat was steaming 29% knots oue of the Admiralty 
officials wrote his name on a piece of paper which was resting 
on the deck at the stern, and tnough the writing shows slight 
evidence of tremor it is perfectly distinot. 
"Although the idea of placing the engine cylinders at a small 
inclination from the vertical, and the ueviee Oi having the main 
standards over the main bearings (the latter was, we belkve, 
first introduced by the H.-m-shoffs in some vedeite boais built 
for the British iSavy in 1883), are not new, the engines we now 
illustrate show a bold uep.irture from recognized practice, and 
Messrs. Thornycroft are to be congratulated on tne reuiarkaoie 
success that has attended their • xcuision into the often danger- 
ous territory of originality in mechanical design. 
"The boilers oi the Daring are of the new Thornycroit water- 
tube type, three in number, and have a total heating surface of 
close upon 8,000sq. ft., the grate sunace being 180sq. ft. The 
propellers are three-bladed, the blades being of phosphor 
bronze. 
"On the preliminary trial above referred to, when a speed of 
29.268 knots was reached oa on) ran, the boiler pressure was 
215ibs. to the square inch, and the revolutions 395 per minute. 
The power given off by the main engines was ±,842 indicated 
horse-power. 
"With regard to other novel points oi th i design. Fig. 4 shows 
the details of the cross-bearers of the engine. Striotiy speak- 
ing, there is no bedplate to these engines, the oross-uearers 
being attached to the floors and longitudinals of the hull by a 
single boit at each end as shown, rue bearers however, are 
conuected together longitudinally in the front by a stout steel 
angle-bar, which is plainly shown in Fie:. 2, and m section iu 
Fig. 3. it should be noted that our engravings, Figs. 1 and 2, 
have been prepare 1 from photographs taken when the engines 
were standing in the erecting shop. Our readers will distinguish 
between the four erecting-blocks shown on the timbers and the 
engines themselves. The latter end with the angle-bar shown. 
At the back the cross-bearers are connected by a steel plate 
plainly illustrated in Fig. 1, where three timber erecting-blocks 
are also shown. It should be stated that when complete the 
cylinders nave coverings ol sheet steel, which give tneui a more 
sightly appear nee than they have m our illustrations, although 
as uepicted a better idea is gained of the general design. lug. 5 
il ustrates a device which has been introduced tor facilitating 
the removal of the main bearing keeps. In place ol the columns 
passing through holes, as was the case in the Daring's engines, 
a notch is provided, as shown, and by tilting the keeps they can 
be removed bodily. In order that the useful effect ot the keep 
in tying together the two sides of the cross-gitder may not be 
lost, the part where the uuts bed is recessed as shown. Fig. 6 
illustrates the method followed of preventing end shake in the 
columns. There is a wedge which can be set up by the nut, 
thus pressing the column upward and jamming the thread of 
the screw. Fig. 7 shows in section a steam-reducing valve 
placed on the connections between the high and intermediate 
pressure cylinders, ihe chiei object of this is to equalize the 
load on the two cranks at starting,. St-am passes into the annu- 
lar apace bhown and lifts the c lindric il valve in the center with 
turned-over lip as shown. This a.lows steam to escape through 
the branch at tne back. As will be seen, the valve is of the 
differential type. Its action may be expressed as lollows: If 
tne area of the upp^-r side of the valve is n times the area of the 
annular lower side, the valve will close when the steam pressure 
above the valve is more than — th of that below the valve, and 
n 
will again open if the pressure falls beljw that limit. Thus the 
valve will taue steam from the engine side of the main stop 
1 
valve, and deliver it reduced to — th of its initial pressure to the 
/ « 
intermediate steam chest (by means of the pipe shown in Figs. 
1 and 2) as soon .is steam is a imitted to the high preasur cylin- 
der, and will automatically close as so >n as the pressure from 
the exhaust steam from the high-p.essure cylinder is greater 
1 
than — th that of the initial steam pressure. A similar valve 
n 
was also fitted in the Daring's engines between the intermediate 
and the Jovv-pres ure cylinders, as show.i in Fig. 1, This 
enabled the low-pressure pistons to start the en ;ine if the high 
and intermediate cranks were on fclw'Jr dead centers. 
We append a copy of the details of the runs on the mile made 
during the official contract trial; the displacement ^being about 
240 tons on a draft of 5ft. 7%in. forward and 6ft. ll^in. alt. 
a 
0 
o 
53 
32 
o 
Mean of 
means . . 
Do lor both 
engines. . 
Revolutions per 
Minute. 
Starboard. 
379.8 
395.1 
330.0 
389 2 
386.4 
389.0 
389 38 
Port. 
380.8 
392.9 
389.5 
389.2 
386.9 
391.4 
389.15 
Speed in 
Knots. 
29.032 
27.190 
29.364 
27.314 
28.800 
27.692 
First 
Mean. 
28.111 
28.277 
28.339 
28.057 
28.246 
Second 
Mean. 
28.194 
28.308 
28.198 
28.151 
True mean speed, 28.213 
389.26 
Mean indicated horse 
power=4044. 
"On Nov. 9 there was made a preliminary trial ol the torpedo 
boat destroyer Ardent, the first of three sister vessels which 
have been built by Messrs. J. I. Thornycroit & Co., of Cniswiok, 
to the order of the Admiralty. The torpedo-boat destroyer 
class, like all otuer types in the Royal Navy, is still growing ; the 
new vessels, of which the Ardent is the first, are lint, longer 
than the destroyers Daring and Decoy, lately completed for the 
Government by this llrrn. The engines are similar to those of 
the Daring, which we recently illustrated and described. The 
Ardent is, therefore, 2U0it. long, ldft. wide and 14it. deep, the 
latter dimensions being l:t. greater than in the Daring and 
Decoy. The description ot the latter vessels in our issue of 
June 29 last, will apply generally to the Arnent, so we need not 
go again into details. The vessel ib twin-screw, and the engines 
are ot the three-stage compound type, having cylinders 19iu. in 
diameter and 27iu. in diameter for tho high and intermediate 
pressure cylinders respectively, while there are two low-pres- 
sure cylinders to each set of engines, each oi which is also 27in. 
in diameter. Ihe boilers are uf the 1'hornycroft type, similar in 
general design to those of the xlaring. In the Paring's boilers 
there were two close walls of tubes forming the exterior of the 
furnace space or combustion chamber; tne products of combus- 
tiou passing to a space, or uptake, iu the cent r of the boiler 
between the two furnace*. In the Ardours boilers the same 
outer rows of adjacent tubes are retained, out bent inward 
toward the furnace space is a row ol other tubes, which, how- 
ever, are not touching each other, so that the heating gases can 
pass between them to the wa Is of tubes at the back, in this 
way an add tion has been made to heaiing surlace, and, tuough 
the back tubes are somewhat masked, the arrangement has re- 
sulted in more steam being generated, with a corresponding 
increase in power developed by the engines. 
H.M.S. AEDENT, AT THE MAPLIN, NOV. 9, 1894. 
WITH NATURAL DBAFT. 
Number of Run. 
a 
Receiver 
Pressure. 
£_ 
Revolu- 
tions. 
Time. 
Speed. 
Mean Speed. 
►4 
M 
CM 
hj 
Port. 
Star- 
board. 
Lbs. 
Lbs. 
Lbs. 
In. 
M.S. 
Knots. 
Knots. 
1 
110 
42 
10 
27 
280 
277 
2 48 
21.429 
2 
85 
40 
9 
27 
269 
269 
3 22 
17 322 
19.275 
3 
90 
39 
8 
27 
272 
269 
2 51.2 
21.028 
WITH %IN. AIE PBESST/EE. 
1 
160 
80 
24 
26 
355 
351 
2 11.8 
27.314 
26.787 
2 
167 
84 
27 
2b 
370 
368 
2 19 6 
25.7S9 
3 
160 
78 
26 
2'5 
368 
1 
b66 
t 7.4 
28.258 
WITH 2lN. AIE J?BESS QBE. 
200 
100 
43 
24 
411 
408 
2 7.6 
28.214 
195 
95 
41 
407 
405 
1 59.4 
30.151 
29.182 
"The trial of Friday last, as stated, was of a preliminary 
nature, the official trial witn all weights on board b ing yet to 
be made. Occasion was taken, wluu making the preliminary 
trials ot the Daring, to get runs at progressive speeds, and tne 
same course was followed with the Ardent in order to «et 
lurther evide .ce bearing U|>on the performance of these vessels. 
Daring ma e 7.86 knots at 91 revolutions, 14.2 knots at 175 revo- 
lutions, 18.3 knots at 238 revolutions, 23.4 knots at 322 revolu- 
tions, and finally 28.656 kuots at 3i4.3 revolutions, the steam 
pressure being 2)0ibs., an t the power 4-142 in heated horse 
power on the latter run. The table gives the results obtained 
last Friday. 
"It will be seen, therefore, that the Daring's speed has been 
exceeded by the later and longer vessel, but it has required »a 
