The morning news. [volume] (Savannah, Ga.) 1887-1900, 1897-08-24
THE SPEED or STEAMSHIPS.
4 Suggestion That the Limit Has
Nearly Been Reached.
From the New York Tribune.

From the New York Tribune.
A slow. but steady Increase in the speed
of steamships has been effected ever since
that class Of vessels firt came into ex-
istence. Greater length, finer models
higher boiler pressures and engines that
were lighter In proportion to the horse
power developed are among the causes
which have contributed to such a result.
At present the limit for ocean liners and
frst-class cruisers Is about twenty-five
knots A few private yachts do better
than this But the best time at sea is
made by torpedo-boat destroyers. Two or
three years ago n and % knots was the
maximum speed of such craft. France
now has two, and England FIVE or six
deslroyers able TO make between 30 and
81 knots and several more have been
projected which must attain a speed OF
81 in order TO be accepted. That marvel
Of marine architecture and engineering,
the Turbinia, has already exceeded this
figure, however having spurted at tho
rate OF "a knots record not likely to be
beaten for some months at least; perhaps
not for years.
A possible obstacle to great advances
in speed I'm the future, dimly limited at In
1895, was discussed at length few weeks
ago, at a scientific congress In England,
by Sydney w. Barnaby. When the tor
pedo-bO destroyer Daring made her first
Velop the speed which had been expected
by her designers and builders. There
seemed to be an unaccountable waste OF
power somewhere. Mr. Barnaby dag
nosed the case, reached certain conclu-
sion as TO the nature Of the trouble, and
prescribed "A remedy. He recommended
some changes In the screws, and his adj
vice was followed. The diameters re-
NAMED the same and the slant Cor pitch)
OF the blades was unaltered. But the
blades were broadened, so that the whole
area OF each screw was increased from a
trihe under nine square feet to trifie
under thirteen Tho speed OF the boat
was thus increased from "A knots to B.4,
with the same expenditure of power. and
the slip OF the screws was diminished
from 30 to 1874 per cent.
Mr., Barnaby's theory was that the high
sped at which the screws rotated formed
cavities IN the water on their front sur
faces. and that this "cavitation' Gas he
calls the phenomenon produced the in
creased slip" and waste OF power. Since
that time he has made some experiments
OF his own that strengthen his convictions,
and he also finds something in the obser-
vations Of other men 10 confirm his Views
as to the genuineness Of the evil referred
TO. In his recent address, therefore, no
remarks:
THAT cavitatlon viii be the cause OF
trouble In the future rs. think, certain.
Already Il Is becoming difficult 10 obtain
the requisite area len screws Of destrOyers
without either resOrting TO an abnormal
width OF blade or 20 larger diameter and
pitch ratio than would otherwise have
been preferable. The one expedlcnt gives
undue surface friction. and the other ne
cessitates reduction In the rate Of revO-
luton, and therefore a heavier engine" Ia
other words. the line OF procedure which
he advised In regard 10 the Daring has al
ready been followed a. far as Is practica-
BILE
That there remains az least one other
means 20 prevent cavtation a. evident
from the success OF the Turhlnia. The re-
markabe speed OF that boat rs, 20 be sure
due in .arge measure TO the new type OF
engines, the steam turbines. which propel
her. But another innovation WIS made Ia
her case In the number and Arrangement
OF her screws. or these she has no less
than nine three being mounted on each
shaft. and her rudder being displaced to
one side OF a vertical plane running fore
and AFT through the center OF the boat
Mr. Barnaby says that the Turbinia's a..
slgner was forced, doubtless against hla
Will 10 employ nine screws" Implying
that there are serious objections 20 such a
plan The obvious success of H.. however.
and the possibility that Htili other romediol
for cdvltntion will b. discovered fusflfv a
hope that Mr.. Barnaby's predictions may
not be- verified. Besides. doairnsrs can
gfeaty improve on che present speed ~
The finest merchant steamship Without
reaching tho limit which boz fears VIII
Htfoyefa