The Baltimore County union. [volume] (Towsontown, Md.) 1865-1909, 1886-03-13
Correspondence Baltimore County Union.
SCIENTIFIC MISCELLANY.
A SAFE LIGHT FOR MINERS.


An electrict safety lamp exhibited by Mr..
j. w. Swan at late meeting of mining and
mechanical engineers at Newcastle, Eng. The
lamp is portable, being fed by secondary bat
terry and the whole weighing about six pounds,
and is said to be capable of giving two or three
times as much light as the ordinary safety lamp
during ten or twelve hours. The supply of cleo
trio energy is readily renewed, and the batteries
of several hundred lamps may be recharged in
few hours by connection with suitable electric
main. Mr.. Swan hopes to give miners still furth-
er security by the addition of foul air detector
to the lamp.
INDUSTRIOUS PROGENY.
Perhaps no more striking illustration Of the
wonderful reproductive powers of certain insects
could be given than that contained ina new work
by Mr.. Theodore Wood, an English entomologist.
1t is assumed, first, that 1000 aphides weigh no
more collectively than single grain; and, Sec
ondly, that only a very stout man can weigh as
much as 100000 grains. Then it is found that
if multiplication were entirely unchecked, the
tenth brood alone of the descendants of single
aphis would be equivalent in point of actual mat
ter to more than 5OO,OOO,OOO of very stout men
or one-thrd of the human population of the globe,
supposing each person to weigh $50 pounds
SOIL FILTERING.
Recent experiments confirm the opinion of sani-
tary authorities that, though natural soil is an
excellent filter for impure air that may pass
Mr.. Raphael Pumpelly, of the national Board of
Health, finds that sand interposes absolutely no
barrier between wells and infection with germs
from cesspools cemeteries etc., lying at great
distances in the lower wet stratum of sand and
that it is probable that dry gravel or possibly
dry sand is obstacle to the free entrance
into houses above of these organisms, which swarm
in the ground air around leaky drains
DETERMINING TREE AGES.
After n careful Studv of the guhiact Prof. p. ID.
Penhallow concludes that the formation of the So
called "annual rings" of growth in trees is chiefly
determined by whatever operates to produce alter
mating periods ofphysiological rest and activity.
In cold climates the rings approximately
correct, but not always certain, index of age. In
warm climates, however, the rings are of no value
in this respect, as the growth is moro likely to
mark period of rainfall than the yearly hot sea-
son of summer.
LIVING MUSCLES IN DEAD BODIES.
Dr. Brown Sequard, the French Psychologist,
has demonstrated that for several weeks after
death, or during the persistence of the rigid
dition which Immediately follows the cessation of
life, the muscles of an animal undergo slow alter
nate contractions and elongations and he reaches
the startling conclusion that the muscles in rigor
morris are not dead, but are still endowed with
vital powers, being, however, in certain chem-
cal condition which is antecedent and prepare
tory to final death.
ARIZ0NAS WONDER.
The silicifed forest of Arizona known as Chal-
cedeny Park, is undoubtedly one of the greatest
of American wonders, remarks Mr.. Geo. F. KuLz.
This marvellous deposit, eight miles south of Cor
RIA, covers thousand acres, and consists of fall
len trees which have become buried and silicifed
into probably million tons of agate and jasper.
Some of the trunks $50 feet long and ten
feet in diameter and others are broken into every
conceivable shape. Slicifed weed is obtained
m re of hnt vhara ole Is
it so beautifully colored as here, every imaginable
shade of red, brown and green being presented
The most remarkable feature of the park, and a
phenomenon perhaps unparalleled, is the natural
bridge, of agatized wood, spanning a canon fifty
five feet WIDE The tree is from three to four feet
in diameter and more than hundred feet of its
length are in sight, both ends being Embedded in
the sandstone at the sides of the canon.
MISCELLANEOUS
Some remarkable and very successful expert
ments have been made at Portsmouth, Eng, on
the use of creosote as steam generator in ships
of war. The creosote is contained in tank, and
kept at uniform temperature and consistency
By steam coils running through it, and steam in
jectors force the vapor into the furnace
Recent surveys show that Russian forests gen.
orally reach their northern limit at II degrees of
latitude, but nearer the Lena they extend nearly
to y degrees.
1t is suggested that the Patagonians may have
lost as much as two inches in stature since the
adoption of constant Notwithstanding, a little
over two centuries ago. They were formerly re-
puted giants, and their bodies are still huge,
while their legs are disproportionately short and
slender.
Extensive experiments are to be made by the
government of Tasmania in naturalizing European
fshes-such as lobsters crabs, turbet and brill
in the waters of that country Similar trials have
been very successful in New Zealand and Aus
trala.
The weather service of Great Britain appears
to be in a somewhat unsatisfactory condition.
Statistics obtained by the House of Lords show
that during period of ten years 100 unprotected
storms visited the British coast, or an average Of
one storm month.
Glass plates have been substituted for copper
in the sheathing of an Italian ship, the advantages
claimed being exemption from oxidation and in
1o 81 AZ The glass was cast. like iron. in
In the latest list the beetles of the American
continent alone number 9,49O species. =