The citizen. (Frederick City, Md.) 1895-1923, 1896-02-28
written for the C1r1zrN.l

corona, though differing from Ront-
gems rays, may affect Photographic
plates through metallic sheets, which
screen out the less refrangible radia-
tons of the solar disc. This is report
ed by David E. Packer, of the Astro-
Physical Station, at South Birming-
ham, England, as result of many ex-
periments since last July. Advantage
has been taken of the discovery in pho
tographing the corona of the uneclips-
ed sun, screens of lead and tin foil and
copper sheet being successfully employ
ed over camera lenses of 4-inch and
1-inch aperture, and the Photographic
plates being affected in proportion to
the thinness and electrical conductive
ity of the screen. Prominent equator
ial extensions over the region of active
sun-spOt groups are the chief features
of the pictures. But much more re-
markable coronal photographs were
obtained without any camera lens,
through a neat pin hole aperture,
which transmits rays of every degree
of refrangibility entirely Unaffected.
In these, interesting and surprising
features of sun-spot development are
shown.
The Carbonic acid in the atmosphere
of Edinburgh has been determined
daily for three years by Dr. G. Hunter
Stewart, of the Public Health Labor
atory. In 1898, the proportion was
1856 parts in 10000; in 1894, S.72; in
1895, 3.45. The amount of carbonic
acid in the air depends largely upon
the character of the ground, and COM
paratively little is yielded by clay
soil. like that OF Edinburgh. Another
influence of soil is noted in cases of
summer diarrhea; the mortality being
much less on clay than on sandy soil.
II is calculated that a modern gun,
throwing a projectile with an initial
velocity of ,979 feet per second, devel-
ops "a, 900, 900 horse power. This how
ever, is for less than 1-100 second at
each discharge, and as the gun is ru-
ined by 100 shots, the total period of
active work of this terrible engine of
destruction is one second.
These estimates of the work obtained
from pound OF coal at different ep-
Ochs of steamship evolution are suppli-
ed 10y an address of Mr.. A. }. McGin-
mis-, as President of the Liverpool En-
gineering Society. III 1910, this con-
sumption of fuel on an ocean steamer
propelled displacement weight of
LOIS ton Knots, or an actual earning
weight of 0057 ton, the hull represent
ing 40 per cent. and the machinery
and fuel 80 per cent. of the displace-
ment. In 1850, with iron vessels and
the screw propeller, a displacement
weight of O.6 ton was propelled knots,
but the earning weight was increased
TO p per ceLt. or Ole. In 1860, with
higher boiler pressure and the surface
condenser, displacement weight of
0.S2 ton was propelled 10 knots and the
earning weight was 80 per cent. or
27 ton. Iu 1870 the compound en-
CINE SO reduced the fuel carried that a
displacement weight of Is tons was
propelled 10 knots, the earning weight
being so per cent. or 90 ton. In 1850,
when passenger and cargo steamers
had separated, the record of tie purely
cargo steamer was 81 displacement
weight of 1.8 tons was propelled 10 |
kuots, the net earning weight being so
per cent, or Los tons. In 1890, when |
steel hulls and triple expansion en-
gines had become universal, the work |
on the cargo boat was 8 SO displace-
ment tons, propelled 10 knots, ana
the earning weight had risen to
5S per cent. or 1913 tons. In 1895 |
there were two classes of cargo |
boats. The work on the ocean |
tramp" was 3.4 displacement tons, |
propelled 81 kuots, with an earning
weight of 80 per cent, or tons; on
the huge cargo vessels of the North |
Atlantic, 3.14 tons propelled IL knots,
earning weight 90 per cent, or L. tons
The express passenger steamers show
more clearly the penalty of speed. On !
these the earning weight propelled for |
each pound of coal per hour was re-
duced from OILS ton in 1881 TO 009 ton |
in 1895; while the increase of speed |
from 10 to Oh knots was obtained ouly
by raising the daily coal consumption !
from 300 to 500 tons.
Twenty years ago the famous Tillery |
seam of coal in South Wales suddenly |
came to an end against great fault or |
dislocaiiOn of the strata. All efforts of |
miners and experts failed to follow it |
lost end of the seam-consisting of Al |
feet of coal in three layers-was dis |
covered, and the mine will again be |
lucrative.
Less than a score of specimens of fos-
sill buiterflies-Of yearly az many gen.
era-have been found. They occur |
only in tertiary deposits, which have |
ielded vast numbers of other objects |
Scudder records that in over $4,000 in !
sects from the small ancient lake of |
Florissant, in Colorado, he found but |
eight butterflies. OF the genera repre- |
scented two exist TO-DAY in both Europe |
aud America, but the species are all |
extinct.
By the apparatus of French chem !
list, E. Hardy, it Is made easy to deter |
mine whether the acetylene in the air |
of room or the fire-damp in a mine is !
approaching a dangerous proportion. i
The apparatus is an accOustical one,
giving to the ear very accurate guam |
titative analysis of mixtures of two /
gases having different densities. A |
micrOphOne is attached to each of two |
sonOrous tubes. which an electric cur