New-York tribune., 1886-04-02
TACTICAL DIAMETER"
NEW AND IMPORTANT NAVAL WORK.

MAXGUvIEs OF TRE BROOKLYN IL NARRA-
GANsy1T BAY.
lYRoM AZ occAsoSAL CORRESPONDENT OF TIE Tribune.
NEWPORT, March 26.-Tbe correspondent of
THE THBUSE having hal his curiosity pqued by witness
ing day by day through December the United States ship
Brooklyn watzing and performing all sorts OF round
dances about the harbor and neshboring regions Of
NGrragansott Bay. falling In with a naval officer.
naturally sought to have his curiosity grathed. and
asked:
What in the name of Nertune the Brooklyn trying
20 cor
Trying to dor echoed the with the gold stnres
on his sicsves Trying to Garry her INSTRUCTIONS
from the Navy Department. suppose"
And what may thoso instructions be, II may be 20
cnrivusi" asked tue correspondent have seen her
leave her berth at the trasing station, up sbove
Gould Island and fuss and foam around there IKE cat
M NJ, hour after hour every fir day, and Days
not 50 far"
We'll. havou't her orders bnt understand she
hss Instructions to ges her tactical diameter by al
known and eoroeivabe methods; ia addition 70 which
she ss been making speed trials forward and backward
over the measured no tu engine power, two thirds
power and half power; md Der officers she really
surprised herself and them by the extraordinary speed
developed. especially in backilS
Tactical disueer," continued the obliging ofleer,
Is The distance Ia right line between the point at
which In turning, steamship puts her helm and
tho pvint OF which her oourec IL exactly reversed Ia
otIer Tords Is Tho diaae OF tho complete circle sho
would make were she 10 continue her circular course,
plus tho distARce In straight limo between the hnish
and The start of that circle, II you understand such
AL apparent Ab.sriiay,'
What diiereneo pray. can there be betwoen the start
aud nisa OF u c!rcio r. queried the scribe.
Meme "f colrse." answered Tho IN blue and gold,
the term circle be used IL its mathematical sense
Considerable however II be used to describe tho oourse
OF shP la sailing cempe.ey around the eoDpass 10 the
fret cruit after her departure from gwen courss-
oSnS her dft angie the ship does not at nrst realize
tao tu oeot of her bel md consequently II cortnu-
Ing her circular with her helm hard over Will
start upon ler second cToe considerably within her rrst
aud vii continue 70 decreaso tho diameter tarcngh
possibly third circle; and It IA thought by
sorao that Ecr minimum or 'Bnsl diameter Is not
attained anti. nye olraos oonpletcd These i've
circles the be colin and free from tide, viii couse-
qnently orI instead OF hve true ani complete crcIe
gradually dirnishiDs spirn though with little any
difference Of diameter after Second third Sh) )uld
he ship geveT he subjected to str0ng tidal Influences
thon Instead OF hsr COURSE being circular II VIII be
cptos. til Lang aud short log ~ bhe spiral.
Tho tide does not however, grotty change the ships
cactea diameter II constant force. though 1t does
materially affect hsr adyruc-' or forward movement
while making the transfer OF Literal movement
the frat 9Os OF circle Winds and Ooai
currents have als0 much influence
rhc tactical diameter Ia, OF course. greatly
affected ny the helm angle and within the Limit OF say
400 glo greater The eln anglo the less the tactical
diameter, though in "a Inverse proportion That
roy th. tactical diameter AT 200 helm anglo WI not
bs twice rs great 4oo but yet VII be very percep
by grOaier. H. for exa@pie, ship 800 eot Ia nstA
With her holm port 400 from the line, has
tactical diameter of 800 teet, then, with her helm
hall oyeT or 20' rOin tho liDs, she Will have
tactical diameter OF. approximately, 100 feet
Again other things Dsas squl obviously the shorter
Tie ship ths loss wiz ba her actie diameter and yoL
rr,chcsly h.s ia not Always tue whbrs there
ara suai ccr apparent why It should Not pa
80 Here, io example. you the Br0oklya aod tic
Dsu,tch eIperipen ting side By siae and although ths
Brooklyn Is pluoh the Larger and lenFer vessel
appears turn In smsler circle tlsn tie Dispatch.
Tue Brooklyn indeel, is exceptionally vbeont her
helm Further in practice 1t IS found that at tile
helm angle all single vessels turn In smaller
circle or with loss tactical diameter, TO Alto
10 tue other That is say vessel with right hand
screw vel Immersed Will answer more quickly and
moro faetprty port heln, while with left hand
.crsy she Viii prove obed!ent TO starboard helm
II tho screw the surface. however. she edeot &,
reversed Still again. 10 any given helm angle the
tactical iisuet,r lfectci By the specd Of tho ship
These diverse conditions and influences render is
a.esaar, la order obtain tho tactical dIneter
Of 4. xesso, an, krowie1gs Of her mahouvrius
Qualities that q series OF nys circos should be msds
.outipuousiy under each OF the fol.oN oondb
tiohsi