The Baltimore County union. [volume] (Towsontown, Md.) 1865-1909, 1885-12-05
Correspondence Baltimore County Union.
SCIENTIFIC MISCELLANY.
ANTIQUITY OF BRIDGES.


The first bridges were of wood, and the earliest
of which we have any account was built in Rome
500 years B. C. The next was erected by Julius
Caesar for the passage of his army across the
Rhine. Trajan's great bridge over the Danube,
4,77O feet long, was made of timber, with stone
piers. The Romans also built the first stone
bridge, which crossed the Tiber. Suspension
bridges are of remote origin. A Chinese one
mentioned by Kirchen was made of chains sup
porting roadway $50 feet in length, was built
A. d. IS, and is still to be seen. The first large
Iron bridge was erected over the Severn in 1777.
Tue age of railways has brought remarkable
development in this branch of engineering, espe-
cially in the construction of bridges of iron and
steel.
ANOTHER ALUMINIUM PROCESS.
In a new French process an electric current acts
upon a saturated solution of sulphate of aluminium
in the presence of solution of common salt, the
two solutions being separated by porous vessel.
A double chloride of aluminium and sodium is
formed, which is decomposed and the aluminium
set free is deposited on the negative electrode.-
1t is claimed that the important result fcheapen-
ing the manufacture of aluminium may be accom-
plished by this method.
BRAINS TERTIARY TIMES.
In paper on the size of the brain in extinct
animals, Prof. Marsh, of Yale College, has brought
forward the remarkable fact that in the race for
life during past ages the survival of any partcu-
brain as compared with that of their contempt
raries of the same class Brains won then, as
now, and the brain of animals crushed out of ex-
istence was always found to be relatively smaller
than that Of those OUTLYING them.
ARTIFICIAL PETROLEUM.
The action of superheated steam on molten cast
iron, rich in carbon, has yielded product denti-
cal with the Hydrocarbons forming crude petrole-
um. Berthelot thinks this discovery offers pos
sible explanation of the origin of petroleum, viz.
Sea-water penetrates assures to depths where the
earth is very hot, forming superheated steam,
which, coming in contact with melted iron rich in
carbon, is decomposed into hydrogen and oxygen.
The oxygen unites with the iron to form oxide of
iron, and the hydrogen combines with the carbon,
the resulting hydrocarbons passing in gaseous
state to rockstrata suitable for their condensation
as oil.
THE SOUND OF THE AURORA.
In response to some thousands of circulars, DR..
Sophus Tromholt has received the testimony of
IA persons in Norway concerning the emission
Of sound by the northern lights. Of these per-
sons 92 believe in the aurora-sound and 90 assert
that they have heard it themselves. The sound
is variously described as sizzling, kissing, whiz-
zing, cracking, rushing, ripping, rolling, flap
ping, creaking, roaring, etc.
MISCELLANEOUS.
In recent experiments the average crushing
force resisted by red bricks was $3.50 pounds per
square inch. They were slightly cracked. Bricks
supporting about seventh of this load-or GO
tons per square foot, have been accepted as safe
for high towers if still uncracked. At the base
of the tallest brick structure in existence-the
famous chimney of 420 feet in height at st. Roll
lox, Gasgow-the pressure is calculated at 6,67O
pounds per square foot.
fine skeleton of the sea-cow (Rhytina gigas)
has just been procured from Behring's Island for
the British Museum. As recently 174l this
1.,kL L.,
five feet in length and weighing from three to four
tons, was quite abundant off the shores of Alaska
and Kamschatka, but has now become totally ex-
tinct.
An account of the "Anemogene," an apparatus
for initiating the great movements of the earths
atmosphere, has been given to the French Acade-
my of Sciences. By means of this instrument,
which takes the form of a miniature revolving
globe, the trade winds, ascending and descending
currents, and other normal atmospheric phenom-
ena, are reproduced.
The thirty inch object glass of the new tele-
scope at Pulkowa, the greatest refractor in
the world, has been carefully tested, and so
excellent have been its performances that the
rarely bestowed tribute of the honorary gold
madal of the Russian Empire has been conferred
upon its makers-the Messrs Clark, of Cambridge,
Mass.
Cases of lead-poisoning in Paris have been
traced to bread and -four, a miller having filled
up certain holes in his mill stones with lead.
A favorite prehistoric unit of measurement, ac-
cording to Mr.. R. P. Gray, was eleven inches,
and may have been derived from the length of
the human foot.
The best fltering agent, according to the recent
experiments of DR.. Percy FARMLAND, is spongy
iron. Powdered coke ranks next, and is very
good but animal charcoal soon becomes worse
than useless, although excellent at first.
The water in the Gulf of Bothnia is reported to
be falling quite rapidly. One proof of this is the
fact that large stone on the Swedish coast now
rises three feet above water at mean tide while
fifty years ago it was barely visible at lowest tide.
An English astronomer considers that his fox
terrier has the intellectual development of child
two years old.