The Detroit times. [volume] (Detroit, Mich.) 1903-1920, 1910-11-25


sensitiveness to -
heat. Others had perfected various
kinds OF heat-measuring instruments,
but none Of them was sensitive
enough to tell Professor Langley
what he wanted to know. At another
time he was trying to make the birds
tell him their secret OF flight; but
there was no means of communication
between them. SO he fitted up a pair
of shotgun cameras" electrically
connected together. He had two Of
his assistants watch bird and at an
agreed time to point their camera
guns at the bird from different
angles. When one of the operators
got a good view, he pulled the trig-
ger and both cameras snapped stimuli
taneously. The result was that the
birds picture was secured at different
angles at precisely the same moment.
When Professor A. A. Nicholson OF
Chicago, sought an extremely accur-
ate measure Of length, he found that
the most delicate measure In exist
ence was not accurate enough to suit
his purposes. So he determined TO
solve the problem OF accurate linear
measurement. He devised an instru-
ment called the interferometer When
he had perfected 1t, he found he had
produced a machine that would tell the
length OF anything, even down to the
one five-millionth part of an inch.
Professor Nicholson found that light
waves were almost exactly like the
water waves made when two stones
are cast simultaneously into still
! pond. II the two circles interfere,
they quickly wear each other down:
but IL they coincide, the height OF the
little waves is Increased.
Humanity's debt to delicate scienti-
fc instruments Is we'll illustrated by
three things used by the scientist
the microscope, the telescope. and
| the spectroscope, none or which was
invented by an American, but all OF
which have been used by Americans
to make some wonderful discovery in
the realm of science. With the mis-
roscope, man has been able to Invade
the regions OF the infinitisemal
while the telescope has carried him
into the realms of the infinite. The
marvels of modern surgery came
| from knowledge gained with the mic
roscope, and the whole germ tribe
was discovered by it's use. For thou
! sands of years men lived all uncon-
scious that such things as germs
existed. Then a doctor held a misro-
scope to a drop of blood and new
world of living creatures was discov-
cred. Numberless inventions and dis
coveries have been based on this in
strument. In the case OF the telescope,
our time, our modern methods of sur
veying and our mastery OF the laws
of gravity and motion are practical
things which may be traced to 1t.
With the spectroscope the artisan
is able to determine the properties
of such mundane stuff as common
sugar; while the astronomer Is able
to go trillions of miles into space and
catch rays of light which tell him
what kinds of matter are found i'll
the star which he is studying. The
old-fashioned prism, through which n
ray of light looked like a rainbow, is
the simplest form of the spectroscope.
With this instrument, minerals have
been found in the stars before they
were discovered in the earth. In
the arts, the spectroscope is used in
the analysis of sugar: IL Is used TO
show the exact moment when iron is
converted into steel when in the con-
verter; and Is great aid In the de-
lection OF adulterants in foods. 1t is
in these fields that the Americans
have made the best use of the spec
troscope. II will also inform It's own
er whether the thousandth part of
grain of dried blood Is Of human or
, animal origin. When the chemist
goes into court and swears positively
that a certain red splotch in the evil
dence is human blood, he predicates
his oath upon his spectroscopic
analysis.
The accuracy of weighing instru-
ments is no less remarkable than
those which measure length, heat or
other qualities. Scales of such ex-
IRENE sensitiveness have been de-
vised in America that they will reg
lister difference of one-fve-hundredth
of a milligram. We get an idea of
what this means by the following IL
lustration: II two weights of COM
mon shape, each weighing two
pounds, were placed on one side OF
the scales, and two others exactly
like them were placed in identical po-
sitions on the other side, there would
be a perfect balance. But II on one
side. one weight should be put on top
of the other, the bare two inches OF
difference In the distance OF that
weight from the center OF the earth,
would cause the scales to register the
difference in weight. In other words,
SO refined are these balances that
they will tell the difference In weight
OF a two-pound block OF steel when
moved two inches farther from, or
nearer to, the center of the earth.
Even in the machine shop one
comes across instruments of remark
able precision. There are many ma
chimes made in which the difference
OF thousandth part OF an inch would
be the difference between success and
failure. Therefore. micrometers OF
unusual delicacy are required. Some
OF these possess screws OF forty turns
to the inch, and there is a scale like
that on a combination lock. which
registers the twenty-ffth part OF a
turn. Thus the machinist, by the
turning OF a little screw, is able to
tell to the observation-disclosures
part of an inch whether his work Is
accurate or not. The practicability
OF this knowledge is shown by the
fact that the main difficulty Watt OK
perienced In inventing the steam en-
CINE was in getting cylinder aud
.tota toll hold