The Baltimore County union. [volume] (Towsontown, Md.) 1865-1909, 1886-06-12
SCIENTIFIC MISCELLANY.
PERCEPTION OF coLoRs.


Sensations of vision require definite time of
exposure of the retina, which time Mr.. J. NJ. Cat
tell, Of the University of Leipsic, finds to be
siderably dependent on the nature of the object
and the intensity of the light. 1t varies with the
several colors. Orange gives the quickest impress
sion the eye, and yellow closely follows it, then
come blue, red and green while the retina is
is least sensitive to violet light the time for which
from two to three times as long as for orange.
By lamp-light the eye works more slowly than
by daylight, and the order perceiving colors is
changed to orange, red, yellow, violet and blue.
AN OVERLOOKED MATERIAL.
A German writer remarks that the compound
known "Zeiodelite," discovered by Simon, has
not been used SO much as its peculiar advantages
would seem to suggest. 1t is prepared by mixing
25 to 80 parts of powdered glass with 20 parts Of
melted sulphur. This may be shaped into any
design; and it cools into stony hardness resist
ing boiling water and the strongest acids. 1t can
be united at heat Of 400 degrees.
RESULTS OF ENGLISH SANITATION.
Improved health laws appear to have produced
remarkable results in England and Wales, de-
cided reduction in the death rate having now been
maintained for ten years and been much greater
during the second half of that period than in the
first So great has been the recent reduction that,
as the registrar general points out, more than
$4,000 persons survived the last five years whose
deaths would have been recorded had the mean
rate of mortality been equal to that prevailing in
the ten years 1S71-S0. The effect on longevity
has been indicated by Mr.. Noel Humphrey, who
states that the reduction in the death-rate from
22.5 in 1s3s-54 to 20.s in 1s76-S0 has added two
years to the life of every male born, and three
years and half to that of every female.
INSECT SMELL.
In an extensive series of experiments by Prof.
GRADER, insects and many other invertebrates
perceived odors much more quickly and acutely
than the vertebrates tested (birds and reptiles.)
The antennae proved to be not the only organs
of smell in insects, although these appear to be
essential to the perception of some fine odors. In
some the palpi of the mouth organs are more
sensitive than the antennae, but perception of
smell through the stigmata or respiratory organs
is not rapid nor important.
AN INTERESTING PET.
The Beaked Chaetodon of the Indian and Poly
nesian seas is fish of eccentric form and beaut-
full tints but its most remarkable feature is its Gu
riously elongated muzzle beak which is en-
ployed as a gun, with drop of water for bullet.
Unlike other fishes, this creature does not wait for
its prey to fall into the water, but shoots it down
like true sportsman. Seeing fly or other in
sect on a twigi over the water, the ChaetodoD
quietly approaches and, with its nose just above
the surface, accurately projects drop of water
from its perch and is quickly snapped up by the
fish. The 6nny archer is highly priced house.
hold pet by the Japanese, who keep it in bowls
and amuse themselves by watching it "shoot"
flies held up before it.
WORK OF oBsERvAToRIEs
Progress in astronomy no longer depends upon
chance observation, but is new effected by di-
vision of labor and concentration at certain
points upon some one particular object ofresearch.
The leading observatores all work at specialties.
At Harvard the relative magnitude of the stars
receives chief attention. at Princeton, spectros-
copy; at Allegheny Observatory, the dark part
of the solar spectrum and the effect of the invsi-
Bile heat rays the earth at the National OBJ
servatory, positions and orbits of satellites at
Cincinnati, double stars; at Chicago, the surface
of Jupiter; and at Albany and Yale, the perfect
ing of maps of the heavens.
MISCELLANEOUS.
workshop OF the stone age has been discover
ed near the gates of Paris. and has yielded nearly
900 hand-worked fints, including pieces of pol
ished hatchets, scrapers, blades, points, and two
or three little polishers.
An electric light dynamo in London is driven
by steam engine which is said to make Il, 900
revolutions per minute, and is claimed to be the
first motor ever made to work at the actual velo-
city of the steam as it escapes from the boiler.
spiny African caterpillar, seven inches long
and of a steel gray color, was exhibited at re-
cent meeting of the Linnean Society of London.
Penkert has determined that in the Swan cleo
trio lamp the proportion of the energy transform
ed solely into lights ISL per cent in the Siemens,
27.9; in the Edison, 25.5 and in the arc lamp,
1873.
Instantaneous photographs of the hearts and
intestines of various animals have enabled DR.. w.
G. Thompson to determine the action of the organs
more clearly and accurately than is possible by
other methods. Such photographs may prove of
great value in showing changes effected by drugs,
as well as in their physiological teachings.
german chemist, Prof. c. Winkler, has dis
covered new element-"Germanium"- min
eral named Argyrodite, which consists chiefly of
sulphur, silver and mercury.
Primrose seeds from height of II, 900 to Is 900
feet in the Himalayas have been received at Cal
cutta, and some are to be planted in England.
Il