El Paso herald. (El Paso, Tex.) 1901-1931, 1910-11-24

which he is studying. The Old-fashion-
ed prism, through which ray of light
looked like a rainbow, is the simplest
form of the spectroscOpe- With this in
strument minerals have been found in
the stars before they were discovered
in the earth. In the arts, the spectre
scope is used in the analysis of sugar;
it is used to show the exact moment
when iron is converted into steel when
in the converter; and is a great aid In
the detection of authorizations in foods
1t is in these fields that the Americans
have made the best use of the spctrO-
scope 1t will also inform its owner
whether the thOusandth part of grain
of dried blood is of human or animal
origin. When the chemist goes into
court ard swears positively that a GER
tain red spIotch in the evidence is hui
man blood, he predicates his oath upon
his spectrOscopic analysis.
Accuracy in Weighing.
The accuracy Of weighing instru-
ments is no less remarkable than those
which measure length, heat or other
qualities Scales of such extreme SEN
sitivenesS have been devised in America
that they will register a difference of
one-five- hundredth of milligram. We
get an idea of what this means by the
following Illustration: If two weights
of common shape, each weighing two
pounds, were placed on one side of the
scales, and two others exactly like
them were placed in identical positions
on the other side, there would be d
perfect balance. But if 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 viii tell the
difference in weight of "a wo-pOund
block of steel when moved ,wo inches
farther from, or nearer to, the center
of the Earth.
Even in the machine shop one comes
across instruments Of remarkable pre-
cisiOn- There are many machines made
in which the difference Of a thouSandth
part Of an inch would be the difference
between success and failure There
fore, 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 combi-
nation lock, which registers the TWEEN
ty-fifth part of q turn Thus the ma
chinist, by the turning of little screw,
is able TO tell to the One-hundred-thou-
sandth part of an inch whether his
work is accurate or not. The practical
bility of this knowledge is shown by
the fact that the main difficulty Watt
experienced in inventing the steam en-
CINE was in getting a cylinder and
pistonrod tight enough to hold steam
and yet permit the back and forth mo-
ton of the piston
Power With DeIicacy.
Science. however, does not require
only delicate instruments. Some of the
apparatus must be as powerful as the
| other instruments are delicate For in
| stance. the huge equilatoral telescope
must be operated by hydraulic meth
/ DDS, and must condense the light gath
| cred on a 20 inch glass into a little
/ thread of light which will pass through
/ a pinhOle. There must be measuring
4. machines which will register a pres
| sure of a million pounds on the one
hand, or the effort required to crack