The Baltimore County union. [volume] (Towsontown, Md.) 1865-1909, 1885-07-18
Correspondence Baltimore County Union.
SCIENTIFIC MISCELLANY.
A PROBLEM SOLVED.

Preliminary trials with apparatus specially
constructed for photographing the stars have been
made at the Paris Observatory during the past
year. The results have been SO satisfactory that
Admiral Mouchez now declares the problem of
making charts of the heavens, including all stars
down to the fifteenth magnitude, to be solved
Photographic impressions of stars visible to the
naked eye are taken with minimum exposure of
one-hundredth to one-half of a second, while for
the faintest stars-those of the fifteenth and six
teenth magnitudes-an hour and half or more
is necessary.
GROWING WORLD.
Drs. Kleiber and Keller, of st. Petersburg, have
been studying the increase of the earth's mass
from the addition of meteors drawn from space
They have calculated that about 900 meteors
fall on the surface of the earth each hour andthat
the weight of the foreign material thus added must
be as much as 1890 pounds hourly, or nearly six
ty tons daily.
sENsE-PoINTs OF THE SKIN.
Blk, of Upsala and Gutenberg, of Berlin, have
observed that there are definite points on the skin
at which sensations of cold only are aroused;
others, distinct from the first and equally definite,
for the sensation of heat while between the two
sets of spots sensations of pressure only are
aroused. Donaldson, an American experimenter,
has tried to make accurate maps of the spots of
temperature sensation, and has found that their
distribution differs on different individuals, that
the spots for cold are more numerous than those
for heat while the latter are the more sensitive,
IL. L.. 80 nasty lass than tWel-
ty-fifth of an inch in diameter.
ACCUMULATION IN AFRICA.
Stanley, the American explorer, believes equa-
torial Africa to be habitable for Europeans, and
that with due attention to diet and an occasional
holiday change, they may long retain their full
vigor in the Congo country. On the other hand,
Fischer, German traveller, regards Central Africa
as entirely unsafe for Europeans at lower levels
than 5000 feet and even at that altitude malaria
must be expected on rich land.
DIMENSIONS OF WAVES.
The extreme height reached by ocean waves
according to careful measurements by the hydro
graphical Bureau is from A to As feet, the aver
age height of great waves bong about ~ Rect
During storms in the orth Atlantic, waves some
times extend to a length of 500 and 6OO feet' ana
last ten or eleven seconds while the largest wave
observed is said to have had length of half a
mile, and to have taken % seconds to spend itself.
THE ELECTRICITY OF RAIN.
The suggestion having been made that the lgni-
ton of petroleum tanks may sometimes be caused
nv sharks from the rain of thunder clouds, some
interesting results obtained with an old piece OF
apparatus have been called to mind. In these
experiments on electrometer showed that the drops
of occasional showers are almost always more or
less charged with electricity, and that it is only
totally absent during foggy, moist days, ana long
storms. The strongest charges were obtained
during thunder storms but the air even has
given indications occasionally OF an electrical
charge without any fall of rain.
cARBoNs CHANGES.
Atameeting ofthe Berlin Electrical Society, DR..
Aaron has exhibited specimens of vegetable car
bon which had been transformed into electric con-
ductors and made almost incombustible by ener-
getic and prolonged heating in vacuum or IN
neutral atmosphere. These properties are SO like
those of graphite-the mineral carbon used IN
pencils-that the product may we'll be called arti-
fetal graphite, although it is not crystalline.
ARE OUR LAT1TUDEs CHANGING?
Eleven stars have been selected for observation
at Lisbon and at Washington, to determine
whether those places are changing in latitude
Each star will be observed fifteen or twenty times
yearly with the greatest possible accuracy in re-
cording its position. Observations at Pulkowa
have indicated diminution of about twenty-three
feet in latitude between 1843 and 1872 and greater
changes have been shown AT other observatories
but it is by no means certain that these results
are not due to errors of observation.
MISCELLANEOUS.
Exneriments BY. Baker and Dixon, English
chemists. have shown that highly explosive
mixture of carbonic oxide and oxygen is not explo
siye when dry, and have indicated that molsturels
necessary to ordinary combustion. Paradoxlcal
it must seem, but it is probably true that without
water there could be no fire.
DR.. Andree, of Leipzig, concludes that the
American Indians in columbian times were
unacuuanted with the art of forging iron although
thew knew how to obtain and employ gold, silver,
tin. copper, quicksilver, etc. He thinks that the
great masonry work of Peru may have been built
with bronze tools.
On Russian plains where grass is now unknown
and five out of every six years are generally ram
less, the grass grew thick to the nelgnI Oh a man
sixty years ago. The change is supposed to be
an effect of the destruction OF the vast forests
which once covered the country to the northward.
The velocity of sound in ice has been deter
mined by Trowbridge and McRae to be about
$500 feet per second, about nine times the
velocity of sound in the air.
The former prevalence of sub tropical climate
in England is indicated by the recent discovery
in Cornwall of certain fossils of the tertiary period
of geology. ..--.s-..
new species of ape-worm-mature speci-
mans measnrino from three To eight inehaS in
length-has been found in a trout.
Two French experimenters make the remark
able report that silicon, though unaffected by
temperature of 1870 degrees F., volatilzes at
S24 degrees.