The river press., 1911-10-18
ICEBERG DETECTION.
Rew Mari,e Thern on,eter Records Sea
Temperatures Accurs@e,x

eew Marine Thermometer Records Sea
Temperatures Accurately,
| During the summer of 1910 pxperi.
me!lts were made in the Northern nor.
ton of the gulf Of St. Lawrence with
a new type Of marine thermometer.
the results of which promise to aid in
the detection OF icebergs in fog and
at night.
BY means Of this new type Of ma.
rine thermometer it is possible to re
cord sea temperatures to one oue.thou
sandth Of degree c. The microther-
mometer is of the electrical resistance
type. in which variations of the re-
sistance of the metal wire serve to
give measure of the changes of tenn
perature Of the medium in which the
instrument is immersed. The resist.
ance Of the wire is made so high that
small variations in temperature pro.
duce comparatively great changes in
the resistance.
The coil is made with a resistance Of
1875 ohms and consists OF 25O feet Of
pure iron wire wilk covered and wound
on a copper cylinder about four inches
in diameter and six inches wide. The
cylinder is fitted accurately inside a
second copper cylinder. The euds Of
the cylinders are carefully soldered
and rendered water tight, while the
connecting wires pass out through the
middle Of the outer cylinder. A stout
copper tube is riveted on to the outer
cylinder. to which other copper tubes
can be fastened. The wires pass
through a lead cable to the chart room.
where they are connected to the bridge
for obtaining a measure of the tenn
perature resistance. Thus the absolute
temperature as we'll as the small varia
tions can be accurately measured By
means Of a suitable modification and
combination of Calendar recorder
with the wire bridge it is possible to
record automatically the temperature
to one one-hundredth Of degree.
Readings can be taken every half min
ute. and curves are plotted showing
the variations Of water temperatures.
The instrument is supported over the
side Of the ship about five feet under
the surface Of the water 1t has been
found that the exposure of the bulb of
the thermometer by the waves pro-
duces no irregularities. as the tempera.
ture Of air in direct contact with the
sea does not differ from that of the
water.
Heretofore the proximity of icebergs
6nfn ,ofA1 hr,v q -,
bridge thermometer and by immersing
mercury or alcohol ship thermometer
into buckets of water drawn up from
varying depths. These instruments
are not. as rule. graduated to less
than single degree, which represents
an interval on the stem of only one
eighth Of an inch. Temperatures TAX
en- in this manner. even as often as
four times in an hour in ship going
eight knots. give temperatures only ev-
cry two miles. The temperatures Of
the sea change rapidly in the imme-
date vicinity of an iceberg: hence
comparisons made between observa-
tions taken at intervals of even one
mile are of no value in determining
the presence of icebergs. The oscilla-
tions can be observed only on a con-
tinuous record. On the scale of the
new electrical thermometer single
degree Of temperature is represented
by an interval Of two feet. so that
variations which would be impercepti-
BILE on an ordinary thermometer have a
great effect on this sensitive instru-
ment.