Daily globe. [volume] (St. Paul, Minn.) 1878-1884, 1883-02-01
!. POPULAR SCIENCE.


method of producing artificial iu.lig
has at length been found to be COM
mercially practicable. The indigo
is obtained from isatine chloride,
which in turn is made from benzol.
Natural cayerns of larre SIZE one at
least being six hundred feet long,
have been discovered at West Harp
tree, near Wells, Somersetshire, Eng
land. It is limited that the invesliga-
tions have revealed matters Of great
interest to antiquaries and archie olo-
gists.
j. Mace and w. Nicati, in q paper
on the distribution of light in the
spectrum, say that they consider two
quantities of light rs respectively
equal when they, illuminating one
and the same colorless object, placed
at the same distance from the obserY-
Ell, enable him to see its details with
the same distinction.
While the pendulum is considera-
bly, affected by the near presence OF
dense rocky hills, and by that Of such
small artificial masses as the great
pyramid of Gizeh, huge mountains
like the Himalayas and great elevated
plateaus and tablet lands do not in
fuence the pendulum indications iii
an appreciable degree. III. Faye Of
fers for these and other like facts the
following broad solution: Under the
oceans the globe cools more rapidly
and to a greater depth than beneath
the surface of the continents. At the
depth Of 1000 metres the ocean will
still have a temperature not far from
0 degrees Centigrade, while at SIM
liar depth beneath the earth's crust
the temperature would not be far
from $50 degrees. If the earth had
but one uniform rate of cooling all
over. it, it would be reasonable to as
sumo that the solidifed crust would
have the same thickness and the same
average, density ali over it. Below
the primitive oceans, therefore, the
carth's crust assumed q definite solid
thickness before the continents, and,
III contracting, these thicker portions
exercised q pressure upon the fluid
nucleus tending to elevate the CONT
: hts still higher. In this way the
unequal distribution Of land and sea
at the poles is also explained.
In note to the Paris Academy Prof.
Marangoni gives the results he has ar
rived at III q study of the swimming
bladder. He states, first, that it is
the organ which regulates the migra-
ton of fishes, those fishes that are
made without it not migrating from
the little depth, where they find tep-
id water; while fishes which have
bladder are such as live i'll deep, cold
water, and migrate to deposit their
ova in warmer water near the surface.
Next, fishes do not rise like the Car
tesian diver Gin the well-knoWn ex-
periment), and they have to counter
act the influence Of their swimming
bladder with their fins. If some
small dead and living fishes be put in
a vessel three-Quarters full of water
and the air be compressed or rarefed,
one finds in the former case the dead
fish descend while the living ones
rise, head in advance, to the surface.
3arefying has the opposite effect
Fishes have reason to fear the passive
influences due to hydrostatic pressure;
when fished from great depth, their
bladder seems to be ruptured. Third
ly, the swimming bladder produces
i'll fishes twofold instability-one of
level, the other of position. A fish,
having once adapted its bladder to
live at a certain depth, MAJ, through
the slightest variation Of pressure, be
either forced downward or upward,
aud thus they are i'll unstable equi-
hbrium as to level. AS to position,
Tic bladder being in the ventral re-
:s:,nl, Tie centre OF gravity is above
,ne cen,Ec vi pressure, SO that the
llsIes arc always threatened with in
version; ana, indeed, they take the
inverted position when dead or dying.
This double Instability forces fishes
TO continual gymnastic movement,
ana doubtless helps to render them
strong and agile. The most agile of
terrestrial animals are also those
which have least stability