The Salt Lake herald. [volume] (Salt Lake City [Utah]) 1870-1909, 1897-03-07
OTHER INSTRUMENTS FOR FINE
MEASUREMENTS.

1t is IN electrical work proper, how
ever, that by far the mosS astonishing
has been obtained At the electrical
exposition, held in New York year
ago, a meter was shown which would
measure current of $4,000 amperes
Lord Kelvin devised an instrument
which, as now perfected, will register a
current of one fifty-four millionths of
an ampere; and such a current as is
formed by dipping the tip of a brass
pin and of a steel needle, connected
with the galvonometer, into a drop of
salt water will cause the needle to
swing clear across the scale.
The radio-micrometer constructed by
Professor Vernon Boys, is so delicate
that it will detect and register the rise
of temperature through one-milliontn
of degree. If the reader does not un-
derstand this let him compute that this
extraordinary device will measure the
radiant heat given off by "a candle
flame two miles away And it is moth
ing more than a loop of wire suspended
by a delicate quartz fibre between the
poles of a magnet, the circuit being
closed by a piece of antimony and u
piece of bismuth soldered to minute
disc of copper foil.
Similar instruments have been con-
structed to measure q microvolt Q-1OOc
of a volt) and the resistance of one
millionth of an ohm. A mile of No. 10
copper wire has a resistance or about
an ohm, and Mr.. Tesla has taken sew
eral million volts through his body.
The figures and comparisons given
are we'll enough in their way, but, at
ter all, they convey no very vivid idea
of the micro-coSmic world into which
they penetrate. One or two further il
Illustrations may help to bring this out.
By means of defraction gradings, that
is, fine lines ruled upon glass-and it
is possible to rule these as high as
possible to draw out the little gold
dollar of our currency into wire one
twenty-five hundred-millionth of an
inch in diameter (one-two- and "a half
billionths), that wire would be long
enough to stretch to the sun and back
again 10000 times.
Reaching to such an extreme degree
of tenuity it would seem as if the CROP
ing fundamental mystery of the conStl-
tuition of atoms and molecules; and yet
that mystery would he still locked in
every infinitesimal portion of this min
ute wire A few months ago great
German chemist made computation
to the effect that a cubic centimeter
of. air must contain not less than
1000, 900, DOC, 900, 900, 100000 molecules
Then, by way of illustration of this
unthinkable number, 1t was further
calculated that if an alright vessel,
containing about quart OF air, were
perforated by an electric spark so as
to release 10000, 600 molecules per sec
end (this would be a, vent hole finer
than could be made with the finest
steel needle), it would then require
4o0, ooO. 900 years for such vessel to be
emptied into a perfect vacuum. This
would mean period about four times
as long as life has been possible on this
earth (by latest calculations) to empty
a quartz
Thus, almost incredible as are the.
powers, of present day Instruments,
they are still far away from anything
which can deal with the unthinkably
minute particles which we believe to
make up matter. And, while we arS
about 1t, it will not be amiss to reflect
further>that even with the Infinite atom
as visible to us as the microbe or the
lines of the diatom, we. might stir ma
that these atoms were to each other as
stars and planets floating in that mys-
FERROUS ether whose existence we sus-
pect, but of which we know nothing al
an CARL SNYDER.