Evening star. [volume] (Washington, D.C.) 1854-1972, 1929-04-05
SCIENTISTS STUDY
/ UNUSUAL MAGNET
Powerful Force Is Generated
! by ThermoeIectric Device
4 in New York.
BY H. H. sHELDoN.

BY HI. III. SHELDON.
Much interest has recently been
shown by scientists in New York and
elsewhere in a new thermoelectric mag
net of unusual power. This magnet,
which was first shown in New York at
the American Institute of Science din
ner, is capable of lifting weight OF
more than 200 pounds and has. IN fact,
been shown to be capable, under favor
able conditions, of supporting 400
pound load. 1t can now be seen at the
Museum of Peaceful ARTS on Fortieth
street.
The behavior of this magnet, ac-
tuated as it is by a thermoelectric
current, is so striking that the author
was under the impression that the
whole affair was a hoax. Subsequent
examination and analysis however,
have shown that it accomplishes this
seemingly impossible feat because of
unusually careful design. 1t is the
work of DR.. Paul E. KlopSteg Of the
i Central Scientific Co., who designed it
4 purely for classroom demonstration. No
commercial application is as yet in
sight.
1926 Discovery Applied.
But to appreciate the significance of
the achievement let us see what is the
thermoelectric current which actuateS
this magnet. Seebeck, in 1926, diScov-
cred that if two pieces OF wire OF dlf-
ferent materials, copper and iron, for
example, and at different temperatures,
had their ends joined together cur
rent would flow through them. While
the current so derived from the direct
application of heat has never had any
commercial value because of its feeble
IL ;r ,vo1SN tof
that it points the way to direct gen.
Grafton of electrical power without the
intervention of boilers, dynamos and
all the rest of the paraphernalia ordl-
narily used.
1t has, however, had enormous value
4 as method of measuring temperature.
1t is. the underlying principle OF the
usual commercial pyrometer, which has
Pounds it way into almost every COM
mericial process, especially since the
war Here the metals used are such
that the current produced is pro-
portional to the temperature, and as
a sensitive instrument is used no great
current is necessary.
Stars Temperature Measured.
When many thermocouples are joined
together the instrument is called
thermopile Such an instrument is so
sensitive that if one bundle of juno
tons is turned a star and the other
bundle shaded the stars temperature
can be measured. DR.. E. E. Free re-
Gently demonstrated the sensitivity of
such device by measuring the blush
on young woman'S cheek and its
change under various emotions.
1t has long been the dream of in
ventorS to provide power direct from
sunlight by means of thermopileS. It
has been thought that if one group of
wire functions were exposed to the
direct sunlight and the other group
buried or immersed in water to keep
them at a lower temperature power
could be produced. Such attempts
have always failed, for as more and
more thermocoupleS are added to in
crease the output We are at the same
time adding more and and more electro
cal resistance, with the final result that
all the voltage of additional thermo-
couples is consumed in sending current
through its fellows. This happens before
any current of real value is ever OBJ
tanned.
One inventor working on this prob
lem discovered a useful product, how
ever, in the high resistance wire now
used on electric stoves, coasters and
other electric heating devices. But he
Similar Inventions Recalled.
Up to the present time the most
spectacular results that have been OBJ
tanned were nothing as compared to
this latest feat. Noe, in Germany, con-
Structed a thermocouple which, heated
by a gas film, would ring an electric
bell or charge a battery Wunder con-
Structed one whose current sent through
al Of
support a heavy latchkey. Volkmann
improved this by building one which is
said to have supported 90 Kilograms
(about As pounds. But Klopsteg's sup
ports 400 pounds.
How he does it? Not by many Their
couples with their added resistance.
but with one. Not by an electromag-
net with huge number of turns OF
wire, but by one haying single turn.
The entire apparatus Is SO small that
it can be put into a cigar box. the
effort has been not to produce high
voltage, but to defeat the demon, cleo
trical and resistance, the stubborn indi-
vidual who is not always SO willing to
take orders as we should like to have it
them.
The magnet itself is a disk of soft
iron about inches in diameter and an
inch thick A circular groove is cut
in this and a heavy copper bar bent into
1t. Slots are cut to- allow the ends of
the bar to protrude outward about an
inch or so. These ends are joined by
stout bar of copper-nickel alloy. 1t Is
the junction of this with the copper
that forms the thermocouple.
One End Immersed.
Near each junction there is Gtened
a copper fin of several square inches
in area One of these, in operation. is
heated by a gas flame and serves TO
conduct the heat to the junction, ars1
the other is immersed in a jar of water
for the purpose of keeping the second
junction cool The temperature dlf-
ference between the functions causes
the current to flow through the bar to
actuate the magnet.
A second disk is supplied to which is
attached stout hook and when this
disk is held against the magnet it will
support the weights previously de-
scribed. The faces of the two disks are
carefully machined to afford close mag
retic contact, thing which is essen
tial to the success Of the demonstra-
ton.
It has been computed that with the
temperature difference which exists be-
tween the two functions, probably about
$50 degrees c., there must be voltage
produced Of about fourteen thousandths
of q volt. This would normally produce
little current but under the conditions
of low resistance present, 1t is est