The Salt Lake herald. [volume] (Salt Lake City [Utah]) 1870-1909, 1898-10-16

a heated penny held 20 feet away. NOW,
when these are compared to the gen.
eral heat developed in the galley, or, TO
go further, in the boilers of an ocean
vessel the matter of transmitting that
heat through the atmosphere seems not
so wonderful after all. Herman Her
berts of Newark, n. J., has constructed
an instrument built on the principle OF
the thermopile, which is intended for
use on shipboard. 1t is so sensitive that
it will detect differences in temperature
as slight as one-millionth of a degree
centigrade.
1t may be we'll to state at first how a
thermopile acts. Suppose we take two
pieces of copper wire and secure each
piece to the binding posts of an electric
measuring instrument or galvanome-
ter. We will have naturally two free
ends of copper wire dangling from the
galvanometer. If now we hold one OF
the wire ends to a candle flame and
when it is hot press it hard against the
remaining wire which has not been
heated we will find that an electric
current will be generated which Will
be recorded on the galvanometer. If
one of the wires used is German silver
and the other is copper we Will find the
effect to be very much increased. That
is, a stronger current will flow, or the
same current as before can be gener-
ated with less heat than was used when
both wires were of copper. Yet there
are metals or substances which will be
powerfully affected by much less heat
than is necessary with the combination
of German silver and copper. BiSmuth
and anthony are very sensitive. Sc
lenium is so extremely sensitive that its
conductivity is seriously affected even
by varying degrees of light. There are
other substances quite as easily inf1u
~, 80 -. e.~.1
in the HerbertS thermopile. Not only
will it record the approach of a mass
of heat, but it will also herald the ap-
proach of a mass of cold. Therefore it
will be as useful in denotinS the prox-
unity of an iceberg as in telling of the
approach of a ship. 1t will also indi-
cate the direction from which either
heat or cold is approaching.
Two thermopiles are placed within
case on each side of the vessel. These
cases entirely enclose the thermopilS
except on the side extending away from
the vessel. This formation is designed
to prevent heat radiations from the
ship itself interfering with the accuracy
of the instruments. Surrounding each
casing is an outer chamber containing
an alum solution designed to intercept
direct or reflected heat radiations from
the sun. Above each thermOpile is a
turns in every direction of the compass.
Two thermopiles are contained in each
case simply to increase the accuracy of
the observations. From the thermopileS
wires extend to the pilot house of the
vessel where they connect with a sensi-
tive galvanometer. At each side Of the
galvanOmeter is a bell, one to announce
the heat of approaching vessels; one to
announce the cold of approaching ice
bergs. On foggy days or at night when
the thermopileS are in operation the
tunnels reVolve slowly. If another YES
sci approaches within a mile of the ship
carrying the instruments the delicate
substances of the thermOpiles at once
become affected and an electric current
is generated. This current flows
through the galvanometer in the pilot
house and the needle of the gaIvano-
meter is DETECTED. The DETECTION of the
needle throws one of the bells into cir
cult and the pilot can tell at once
whether he is near another vessel or an
iceberg. The direction of the newcomer
can be determined by noting the pO-
sition of the revolving tunnels every
time the bell rings. 1t may be aScer-
tanned also whether the vessel or ice
berg is approaching or leaving by OBJ
serving whether the power of the Their
mOpileS increases of decreases.
i Somewhat similar to the above in
strument is the bolometer. This appa-
ratus is also affected by the approach
of heat or cold, but in a different way
from its action on the thermOpile. The
thermopile, as stated, creates a current
of electricity when heated. The bolom-
eter, on the other hand. is operated by
a current from a battery, but this cur
rent will regulate it's intensity accord
ing to the degree of heat or cold in
which the bolometer is placed. In its