Daily inter mountain. [volume] (Butte, Mont.) 1881-1901, 1899-04-01
SCIENCE.

SCIENCE.
The new current intorrupter of DR.. A.
Wehnelt of Charlottenburg, is pointed
out by MI. y. A. c. SWinton as much the
most notable Improvement of many years
in connection with The induction coil. and
as likely to find many important applica-
tons in X-ray work, wireless biography,
etc. Without moving parts it converts a
continuous current into a high-freuuency
alternating one. The apparatus is SIM
ply q glass vessel filled With dilute sui
phuric acid. into which dip two cleo
trodes, one being a plate of lead of con-
siderable area, and the other q glass tube
containing mercury and having a pro-
truding bit of platinum wire sealed into
it's bottom. One of the wires from a,
source of continuous current dips into
the mercury. The wire of the tube is i'm
mersed considerably below the surface
and about half an inch from the lead. and
when the current is turned on, a rapidly
intermittent arc, with a probable fire.
Quency of some hundreds per second,
seems to pass between this wire and the
dilute acid. while a torrent of sparks APP
pears between the terminals of the sec
ondary of the evil. The current is passed
directly through the primary of the coil
from the platinum wire and lead plate,
no condenser being used.
An interesting rule for determining the
probability of life is stated by NJ. School
ing of Brussels to have been worked out
by De Moivre, a French mathematician
who removed to England in 1865. 1t is
simply necessary to subtract ones age
from Sc, and to divide the remainder by
2, the result being the number of years
one is likely to live. The chance of living
one year beyond ones present age is
found by NJ. Schooling to be S to 1 at
birth, 119 to 1 at 5 years. 512 to 1 at 10
years, 347 to l at Is years, POI to l at 20
years, 100 to l at so years, and IS to l at
40. OF 1000 persons of 60 years, 500 Will
live to 70 years, 100 to so, and II to 80.
The idea is gaining ground in France
that alcohol from beetroot, etc. can be
made to compete with petroleum for
lighting purposes and that this use of
alcohol would give great encouragement
to French agriculture.
Late repairs on the roof beams of VIM
chester Cathedral. tWO-thirds of which
were so badly WOrm-eaten as to require
replacing with new oak, have made con-
spicuous the work of a remarkable IN
sect. The decay has been due to the ST.
rex Gigas, sometimes known as the horn
tailed saw fly. The fully developed insect
is somewhat less than two inches long,
resembling a large wasp, and the fe-
male is armed With a long and powerful
ovipositor with which it bores holes into
wood for depositing its ggs 1t is the
| grubs Matched from these eggs that
honeycomb the wood, especially fir, Great
ing sad havoc. The actual borer of the
| parent insect, according to Rev. j.. u.
| Wood, is a marvellous instrument beng
straight, stiff and as elastic as a Toledo
rapier: and the microscope shows that It's
head is provided with long, sharp teeth,
sli ghtly curving inward, and serving like
a carpenters center bit, while the shaft is
| armed on each side with sha~rp-edged
| ridges acting exactly as do the sharp
ridges Of a cOffee-mill. No more effective
implement could be devised, and t he bor-
ing tools of modern mechanics are based
on the same principle, though perhaps
| less perfect.
The principal supply Of mica comes
from mines in Bengal. These, says Mr.. A.
Meryin Smith, have been operated from
| a very ancient period, the mica being
still-as for centuries-Only taken out
| from open cuts in the decOmpOsed gram
| lite, new places being sought when the
| solid rock is reached. Large fires are
| built to aid in the work. The consump-
ton of mica is now increasing, but seems
to have been greater at an earlier time,
as the OUTPUT of these mines was eStlmat-
! ed at about $500 tons in 1S49 and only
| about 1000 tons in 1898. The prices OF the
mica range from $500 to 3 or 4 cents per
pound. =
! Comraring the records for fifty one years
! 1S11 -1S91), Mr.. A. r.. Macdonald finds
that the temperature of both Greenwich
and Chicago was above the average dur
ing sixteen winters, and below during
fourteen. There We're nine seasons in
which Greenwich was warmer and Chlca-
go colder thar the average; and twelve
in which Greenwich was colder and Chi
cagO warmer.
European meteorologists have reached
the conclusion, contrary to current pelef,
| that there is no connection between VIM
ter temperature and the height Of the
arometer. as it is quite as often cold
when the barometer is below the average
as when above.
The aluminium furnace having made it
p0ssible to produce very pure chromium
at q. small cost. DIR. Goldschmidt makes
the interesting suggestion that this metal
would be much superior to nickel Tor
plating if it could be used for that pur-
nose. 1t is more stable than nickel, being
as little liable to civilization as gold. NO
method of plating with chromium is yet
known, but, as it could be used as a
soluble anode, it is believed that a prac-
teal process may be devised ere long.
1t aupears that the metallic chromium
| can be reduced in considerable quantities
| for a fraction of a dollar per pound.
A new industry for Australia is prom
Used by the valuable eucalyptus, or blue
! gum tree. An explosive, which has been
named kallenite, is made from the leaves,
and this is said to have five or six times