Evening star., 1921-08-21


EY SHIP SURVEYOR. MODERN YES
of these showed an indication of the
existence of this danger
There are certain areas along our
coasts which have plenty of water
for deep draft vessels, but which can
not be pronounced absolutely safe for
navigation owing to the fact that
pinnacle rocks, coral rocks. or lodges
as characteristic feature. Such
areas are to be found along our At
lantic coast from Maine to Long Island
sound. along the Florida reefs. in
Porto Rico, and particularly in the
areas of Alaska. These hidden dan
gers have been the source Of many
wrecks: numerous rocks and Lodges
on our charts deriving their names from
the vessels wrecked upon them These
distractions being below the surface
OF the water and beyond the range Of
vision from a boat, it is only by
survey with lead and line. This can
be readily understood by considering,
as an analogy. balloon drifting
slowly over a town. The unlikelihood
OF hitting a tower. spire or chimney
stack with q weighted line lowered
vious. It should, theref2re. be, under
stood tha4 ho -matt1rA h1ae flosely
rocky arSas may have been surveyed
with lead and line. there rs still a
possibility of uncharted dangers.
The problem of finding and locating
been changed by the development
OF the submarine. the safe navigation
or which, when submerged, depends
upon the location of dangers at far
greater depths than was ever antici-
pated.
ine case of the Brooklyn in New Bed
ford harbor showed the necessity of
some improved method, other than
soundings. for determining the exist
ence Of dangers. The first step was
pipe carried under the vessel. This
method was used for number of
years along the New England coast
also in. the, waters in the vicinity of
Key West and Porto Rico. The
length of the drag depended. of ne
cessity, upon the breadth of the sur
vsying g.vessel and seldom exceeded
sixty feet. To cover any area was
both laborious and expensive. .
THE French photographic service
has used a long rope sweep sup
ported at intervals by buoys. but a
more promising form. in which wire
replaced the. rope, was used by the
Army engineers in 1902. Starting
with the latter as a basis. drag was
designed in 1904. and successfully
used in Frenchman's bay. Me-. the
party being in charge of photographic
and Geodetic Engineer ID. B. Vain
wright.
Stated briefly. the wire consists of
a horizontal wire maintained at any
desired distance below the surface
of the water by an arrangement Of
weights and adjustable Upright
cables extending up to surface buoys.
This apparatus is towed by two
launches, one at each end. AS the
drag passes through the water it
will catch and show the location
of any obstruction extending above
the plane of the horizontal wire.
knowing the location Of the obstruc-
tion, the least depth can be found on
itsand can be easily found by sound
boat. This method has been used since
that date, and many improvements and
changes have, been made. Hydro
graphic and Geodetfc Engineer n. II.
Heck. with the assistance Of officers
attached to his parties. has been re-
sponsible for the great advance made
in the method Of doing this class Of
work. New equipment Is being used
and the water to be dragged is di-
vided- into two. areas, that In which
it is necessary to drag close to the
bottom. the other in deep water. For
the former. the improved wire drag
is being used. in the latter the So
called wire sweep, which offers much
less water resistance and, therefore,
much greater speed and greater
lengths can be used. Formerly the
communication between the. towing
launches was carried on by signaling;
today the radio-telephone devised
and installed by Capt. Heck is used.
That. the improved wire. drag full
fills it's purpose is shown by the fact
that in the 1000 square miles, Of
water area dragged. $500 unchartei
of which were close to, it, not
actually on the lines Of ocean travel.
A faSt-moving liner striking
pinnacle rock in just the right way
would suffer the fate Of the Titanic,
no matter what precauti6ns were
taken. s..>e SS%. .
The duties Of the members of, the
survey are numerous and complex.
Not only must the men of the survey
secure the Information that is needed.
but they must also record 1t in such
manner that it can be turned over
to. the home office, either by mail or
in person when they return to
There are no ifs and ands about the
business; it must ;be" ex&ct. One must
not imagine. however, that the
activities OF this bureau are. confined
merely to work of the ocean, the
river or the bay. The survey, per-
forms functions OF a fundamental
nature, functions that are of the
utmost Importance, for the maps, that
are made Of various parts Of our
country. whether they ke sfor the
engineer or the automobilishs must
be based on the framework erected