Mineral Point tribune. (Mineral Point, Wis.) 1869-1938, 1875-10-21
MECHANICAL AND SCIENTIFIC.

A very interesting exhibition has
been made before the British Association
of Science, consisting of series of four
teen carefully. constructed thermometers
differing either in the size or shape of the
bulbs or in the material with which they
were filled, some being mercurial and
others containing alcohol, and all being
made in the most perfect manner in re-
spect both to the scientific principle and
the mechanism involved. AS the result of
experiments made with these various in
strlments, under the same circumstances
of temperature and position, it was ascer-
tanned that very large mercurial bulbs are
hut little better than those OF the same
size filled with alcohol, but that with
small bulbs the mercury is much more
sensitive.
The peculiar phenomenon of the
variability of the spectra of glowing gases
has been Investigated by German chem
ist, who finds that this is affected by the
following circumstances, namely: The
density of the gas; the strength of the
galyanic current that heats it, as we'll as
the method of electric discharge, and the
changes of temperature that are produced
thereby; the thickness Of the glowing
stratum of gas; and, finally, the chemical
purity of the gas. With regard to the
density of the gas, it is found that the
diminution of density causes the spectrum
to become fainter and fainter, and leads to
change in the relative position of GER
tain of the bright lines, which sometimes
will become broad bands When the
highest possible degree of rarefaction is
realized, it is found that the bands respect
l,, pf off
that are occasionally merged into each
other, Chicago Tribune.
The atmosphere of Venus is now
subject that is receiving universal atten.
ton from astronomers 1t is known that
many of the observers Of the transit sta
tons, last December, described a beauti-
full phenomenon that occurred as the
planet slowly made its way over the suns
disc A pale circle of white light was
distinctly visible around a portion Of the
planets edge, differing entirely from the
brilliant sunlight, but closely resembling
the soft light of the moon. This ring of
alelight is supposed to be the atmosphere
surrounding the planet and, in the opin-
ion Of many astronomers, it is much deep
er than the atmosphere of the earth. 9th
er observers, however, reject this theory,
and regard the phenomenon as in some
mysterious way connected with the suns
corona. The transit to occur seven years
hence may possibly throw light upon this
problem as well as upon some other re-
lated astronomical questions. -Broo6lW
Eagle.
The combination signal and fash
light is coming into extensive use, its value
consisting in its convenient adaptation as
danger or Geographic signal, always
ready and at hand in case of accidents,
alarms, fogs, or threatened collisions, it
being also a powerful illumination in dark
nights, rendering the smallest objects Wis
ible for many yards distant in all direc-
tons. 1t is an ordinary lantern, in which
lard or sperm-oii is used, with separate
reservoir containing naphtha or volatile
oil held in suspension by cotton batting,
packed in wire gauze sack. By means
of cylinder, or air-tube, passing through
the reservoir common air is injected,
forming, with the volatile oil, hydrogen
bon gas, that escapes through a tube adj
joining the fixed light, thus creating
brilliant flame a foot or more in length.
The apparatus is an improvement on sig
nal-lanterns for railroads, its effect as
signal tlash,light being perfect.-N. Y.
Sun.