New-York tribune., 1918-06-24

and authorized by Josephus Daniels,
Secretary of the Navy, was made pub
lie yesterday by the Naval Consulting
Board, which compiled the pamphlet
with the War Committee Of Technical
Societies.
SO far us security permits, the de-
vices submitted for use against sub
marines are described, and it is made
plain that although new methods are
still being studied the chief reliance
Of merchant vessel to-day is in its
guns, its speed, its low visibility and
vices are used also and apparently are
approaching considerable degree Of
effectiveness. They are almost the only
defence measure mentioned concerning
which the Naval Consulting Board
frankly declines to go into details,
saying:
'Ways and means to tune out ex-
traneous noises, such as the falling
OF rain on the surface Of the water,
the noise of the pumps and other ma
chinery on the boat carrying the
listening device and arrangements to
determine the direction of the source
of, sound, have been given great deal
of study and been developed to a con-
siderable degree of effectiveness. Sound
waves tend to emanate from the
source radially, which is availed Of
However, the details of these devices
are more or less confidential and only
the general principles can be made
available to the public
Transports Use Microphones
1t is added, however, that "many
merchantmen and transports are
equipped with microphones, so that
they may detect the presence of SUBJ
marines"
Elimination of smoke, production Of
a smoke screen and camoufagc paint
ing are the principal methods Of re-
ducing the visibility of vessels and
arc measures still in the process of
perfection, although used with con-
siderable success. Under the most
favorable conditions the submarines
range Of vision does not exceed about
six miles and it's angle of vision by
means Of the tallest periscope, which
alone gives the six-mle range, is
about 45 degrees. In reducing visi
bility, therefore, the navy is operat-
ing against weak point of the sub
marine.
"The point of lookout On a sub
marine being close to the water" says
the Naval Consulting Board, "the po-
sition Of vessel at distance can be
determined only by observing its
smoke, which floats hign IN the air.
Improved smokeless combustion is
therefore desirable.
''In some cases." adds the board, "a
quantity of heavy, black petroleum or
similar substance which will float on
the surface Of the water has been
used to cloud the optical glass in the
periscope's exposed end. However.
in view of the case with which most
of these substances may be washed
off and the vast areas to be covered
tne use mas Deen abaNdOneQ.
Suggestions Are Invited
Painting ships to initiate the appear
ance Of the sea or to break up the
lines of vision is mentioned as af-
fording "relative invisibility," and it
is added that much study has been
given to the value Of a low freeboard
and elimination of masts, stacks and
supcrstructure as a method Of reduc-
ing visibility.
'Suggestions as to any other
method of reducing visibility will be
of interest" says the Naval Consulting
Board. 1t then proceeds to the value
of speed, saying:
"The undeniable evidence Of sub
marine activity which has been ac-
cumulated during the last few months
has demonstrated that the immunity
of a vessel to submarine attack is de-
pendent very largely on its speed and
also its manGuvring ability. The per-
ccntage of vessels having speeds Of
fifteen knots OR more and which have
suffered from submarine attack is very
small, while the loss of slow vessels
having speeds less than that Of sub
merged submarine is practically 100
per cent of those attacked"
The advantage of the convoy system
IS described as very great" Nu-
merous unarmed ships can be protected,
it is said, "by one or two destroyers." !"
In most cases, though, the naval au-
thorities found that experienced skip
pers of swift vessels preferred to put
their trust in their heels rather than
regulate their gait to that of cumber-
some convoy fleet.
"The question as to why submarines
are not destroyed before they reach
the open sea is most natural one," it
is admitted in the pamphlet, which
adds: 1.-THE best answer which it is
possible to give, according to the Of
tlcers OF our navy and those of the
foreign commissions who have visited
this country, is as follows:
"The submarine bases are very
strongly protected by land batteries
aeroplane observers and large areas
of thickly mined waters extending to
such distances that the largest naval
gun cannot get within range of the
bases. Metz, when laid, are promptly
removed by the enemy whose trawlers
are, in turn, attacked by our destroyers
Despite all these projections there is
new going or continuous attempt or
! the part Of the Allied navies to entrar
or otherwise defeat the submarines as
they emerge from the protected areas