The citizen. (Frederick City, Md.) 1895-1923, 1899-07-14
TRIPLE PROPGLLSRS
Chief Engineer Melville shows the Many
Advantages of the 1rip!e over the
Double screw.

Double screw,
Chief Engineer Melville, of our navy,
read paper to the British Institution
of Naval Architects upon the motive
power or warShipS, in which he called
special attention to the triple screw
engines Of the Columbia and the Min
neapOliS. This was missionary work
on the part of our distinguished en-
gineer, for while all first class navies
except Great Britain have adopted the
triple propeller system for some classes
of warships England does not have it
at ali
The French whose Dupuy de Lone,
though not the pioneer of the triple
screw system, took the lead in excit-
ing public interest in it, surpass all
other nations In the number of vessels
and aggregate tonnage to which it is
applied. OF their newer war vessels
there are eight triple screw battle
ships, the Bouvet. 1920 tons; the
Charlemagne, GauloiS aud st. Louis,
1920 each; the MIssena, 1924; the
lena, l2,052; the Magenta and Mar
Ccau. l0,SI0. France evidently consid-
erS the system applicable to the larger
vessels. Then there is the armored
cruiser Jeanne dare, displacing II go
tons with the enormous horse power
of 2S50O tons. Six armored cruisers
Of til" Montcalm class, displacing D.
5l7 tons, with l66OO or more horse
power, also have triple screws. SO do
three new armorpd cruisers of the
nrsaiS class. dispaCing 100 tons.
The lleur ~, diSplaCing S,94S tons,
must he added To the list of big
French vessels with three propellers,
ami so must the % knot cruisers
/ Chateauicuault and Guichen, with 3D.
600 aud - 1000 horse power.
I; is very noticeable. therefore, that
Great Britain does not adopt the syS-
tenn: but it should hc remembered that
il does not give IA higher maximum of
speed than twin screws, if, indeed, as
high rs they In England, too, there
has n"N"r hcru any such question
ahoIt the construction of machinery
/ aS that which recently caused Il resort
/ to triple screws here when we adopt
ed them for the Columbia. it was a
cas- almost of necessity certainly Of
I prud,ucr. No ShattinS has ever been
maGr here heavy enough to transmit
! the - eco horse power designed for
/ III" Columbia to two ScreWH, or lO,5UO
! on each Doubtless that would not
/ have been lasting and fntal objec-
| ton hut there would have been diff
! Guilty and delay in overcoming it,
whereas 1000 horse power on each
| shaft was an easy problem. At that
! tine the little Tripoli. an italian tor
! pcdo cruiser. diSplncing $40 tons, the
| pioneer In the three screw system, was
in service. She had been built at Cas-
trllamarP. near Naples, and her en-
StncS had been made in NewcaStle-On-
| Tyne Besides. France, in the nupuy
de Lomc, OF 6,4OG tons. not far short
OF the Culumbia'S 1850. had shown
that the new system could he applied
10 Shps of large size. Moreover, she
had aSCertained, after experiments
with the steam launch Carpe, how
best To place the screws, that is, not
three abreast, but with the third be-
tween and below the other two and
/ aft OF them.
Chief Engineer Melville, therefore,
was perfectly justified in adopting this
, device. aud, apart from its solving the
! problem OF the Shaftiug. there was
seen to he the economy in the option
OF using one. two or three screws, and
! especially in working one engine at
/ full power iuStcad of two ~ low pow
I or. This consideration Chief Engineer
Melville urged IN Loud0u. pointing out
4 that. III using three smaller screws
4 aud engines, there WAS Il gain Of ; per
] cent in economy in II knot ships and
J ~ per cent in others There is also
/ M 0hvions decrease OF liability to Il
/ total disabling Of the machinery. Each
Shaft has disengaging coupling. 20
/ that when not IN uSe the propeller may
I rcvolvc freely. and the COlumbia's ar
rangemeui OF the screws IS said to
have improved on the Dupuy de
/ Iome's by allowing less interference
from the centre one from water flow
Ing from the other two. Finally with
] three prQppllers. their diancterS are
/ greatly reduced, and both the sides
I aud tie position of the side screws So
cure them better immersion when the
vessel is rolling and pitching than in
the use of twin screws. while the cen
tire one is immersed under nearly all
conditions That means less loss Of
speed from the racing OF the screws
and less protitless wear The careful
records kept of the Columbia and Min
nrapuls during the WAR with Spain
confirms these points. while in Chief
lbn"lHcer MtINHW > "HhHhI itpoit VIC
also find this among his lessons from
the war
''1lat il more than two main engines
are tn he fitted. there should he three
engines driving three screws. and not
two main engines on each shaft The
New York and Brooklyn had their
forward engines disconnected ut the
time Of tbs Santiago fight and could
not stop to couple them. An accident
to any part Of either Of the two en-
ginps on SHAFT dlSableS half the pow
or: in the three screw ship this frac-
ton would be Oily third"
Three miles from the village of Kris.
uvik. in the great volcanic district of
Iceland, there is whole mountain
composed Of eruptve clays and pure