The sun., 1919-01-19
Periscope of a U-boat, with
direction of sight dial.

fire will he actually a. longer rance
than the submarine captain anticipates.
If. on the other hand. the ship is made
to appear more distant than she really
10, then the torpedo may be aimed TO
pass actually ahead Of the vessel.
A choice cannot be arbitrarily made
between the alternatives cited, but that
there should be deception in relation 10
the three factors is clear. The extent ot
the deception desired cannot he precisely
prescribed. 1t would be we'll not TO seek
too much. An error of Is degrees In
course OF two knots IN speed or OF two
TO three hundred yards in range is sut
icient to add materially 10 the safety Of
a vessel against torpedo attack. Any
Illusion. even a slight one. alorg these
lines will be an advantage, since dC-
cuTacy in gun and especially in torpe 10
fire as we'll thr mon6uver OF APP
proach depends intimately upon exact
ness in the estimates Of the targets
range. course and speed
The hearings OF vessels are first taken
by a U-hoat from observation OF smoke
or superstructure. While for ships IN
convoy the smoke. noise and breadth Of
area covered lessen the utility Of super
structure reduction TO lower visibility it
remains ~ value ne an aid TO the defense
OF the solitary ship.
The safety OF ship sur,ject 70 attack
may be said TO vary inversely as the
area over which she is visible to the
submarine.
on sailing ships all superstructurc is
usually needed, but on steamers cons;d-
/ cradle reduction is possible. Masts on
modern vessels serve little purpose save
for the wireless artennaa, the crows nest
and the lights. One mast, In many
cases, will suffice. The Marcon Com
pany Informed the International Mer-
cantle Marine Company thai the aerial
Of the wireless on their vessels could he
run from one mast TO the funnel and
still meet the requirements of service.
scenic Artists Effort.
/ Homer r. Emens. In. veil known
scenic expert. devoted considerable at
/ tention TO the problem OF distortinG the
I apparent perspective Of the upper works
~ a vessel. He prepared a model in
which a large triangular screen " as
placed below the bridge. extending from
side to side. the point Of the triauEle
: facing the bow Of the vessel on each
side of this triangular screen he painted
perspective view of the normal struc.
ture which actually faced the base of
the triangle. The effect Of this was
to make the ship when seen from the
side appear nearly bow on, provided the
error was not corrected by a normal
view Of other portions Of tho ship.
The new ships for the Emergency
Fleet Cooperation have been designed
with low superstructure. \ notable OK,
ample Of vessel with superstruc' are
reduced Is the steamship Naleria. The
vessel was a Cunarder supplied &c
Thomas A. Edison by the Submarine
Defence Association for this expert
mental purpose. The tunnels and maht'
were cut short and character deception
Was sought by Mr.. Edison by means
Of canvas screens strung between tn,
tunnels and certain other parts ~ Nv
superstructure. They were blown off
however. a short time after the vosse
left New York. AS the vessel there
after travelled in convoy no concluSiv,
data have become available. Owing Il
the inherent difficulty OF screening i
seems hardly practical TO RADICAL.
change the character OF vessel.
The field of protective Coloration il
an important one, but one which Il
limited. Vessels in CONVOY or Wit
escort can hardly hope TO be invisible