Omaha daily bee., 1910-02-07

and human blood at that IL can take
a ray OF light coming from a star so dis
tant that the ray has been years in
reaching here and divide It up In such a
way as TO discover the kinds Of matter in
the star from whence the beam comes. In
ibis way the spectroscope found helium in
the sun, ninety million miles distant. be-
fore the chemist discovered IL hard by
his own doorstep.
The spectroscope has hundreds of uses,
some OF them very prosaic. In the Bes-
semer process Ct making steel the object
Is to burn a certain percentage Of the
carbon out OF the ore. II usually takes
about twenty minutes to complete the
process, but II 1t is poured out twenty
seconds too soon or twenty seconds too
late the whole is ruined. The spectroscope
tells the exact instant when the proper
amount of carbon has been burned out.
A remarkable instance of precision in
big things is the case Of the great Yerkes
telescope. A star of the seventh magni-
tude appears to be observation-disclosures
dredth of an inch in diameter. There is
a spider web across the object glass which
is one-six-thousandth Of an inch in diam
eter. The problem is to move this twenty
two-ton telescope with such precision that
the star disc Of ACKNOWLEDGEMENTS
OF an inch can be threaded upon the spider
web of one-six-thousandth of an inch at
all times. and to keep. it moving in oppo-
sition 20 the motion of the earth. This is
accomplished by electrical attachments Of
wonderful accuracy.
The strength testing machines now in
use represent a high type of exact mecha-
nism, possessing as they do the strength Of
q hA,,9.-A 49, "
the delichcy of the hair spring OF a watch.
They register at one effort the tensile
strength of a bar OF iron requiring a mill
lion pounds to pull it apart, and at the
next effort tell to the fraction of an
ounce how much pressure 1t required to
crush an egg shell. They will test the
strength Of a horse hair or that of a gigan-
tic cable with equal exactness. This ma
chine operates en- the principle of the
hydraulic press-2W grains Of weight on
one platform lifting 10000 p&inds on the
other.
The microtome Is another remarkable in
strument of the laboratory. The person
who has seen the breakfast bacon slIcer
in a grocery store will understand some
thing of its principles. When the scientist
wants to examine the cross section of a
little corpsule too small to be picked up
with the hand he e~ncloses it in a coating
of hard p~araffin and that in another coat
ing of softer consistency. Then he puts
it into his little slicing machine and is
able to make slices so thin that it would
require 5000 of them piled on top of one
another to make a stack an inch high.
Shen he melts the paraffin away and
places the almost invisible slice on the
object glass of his microscope.
Time measuring Instruments of precision
were the forerunners of all the delicate
machines of %scietce. Ever since man has
navigated the seas beyond the sight of
land he has needed the most accurate
measures of time in order that he might
tell his longitude with reasonable correct
ness. In liza the English government Of
fered R20. 900 to the man who would devise
q chronometer so accurate that longitude
could be told within thirty miles and de-
scending reward down to half as much for
the person who Gould tell 1t within sixty
miles. In 1865 John Harrison, son of a
Yorkshire carpenter claimed and was
given the highest award. Now chronom-
sters are madehwhich are so accurate that
they will vary only a few seconds in weeks.
The usual battleship carries three chro-
nometers, and the mean time Of the three
is taken as actual time.
There are machines in common use today
which make screws so small that they
appear to be but little particles of dust,
1OO, 900 OF them being required to fill an
ordinary thimble.l Yet each of them must
have a perfect head and a perfect thread.
They are used as screws for the fourth
Jewel wheel of a watch. All the operations
with them are done more by the sense of
touch than OF sight and 1t is marvellous
how acute the human sense of touch may
become. Some time ago a bicycle manufac-
turer brought some balls intended for ball
bearings to matchmaker to show what per-
feet specimens he had produced. The
watchmaker said they were not round and
wagered he could point out three depres-
slons on each ball. A micrometer was APP
piled and it showed that on each ball at
the exact spots pointed out there were de-
presslons of less than the thousandth part
of an inch.
BIZ FREDERIC J. HAsKu.
Tomorrow = Governmental rnvestiga-