The Princeton union. [volume] (Princeton, Minn.) 1876-1976, 1891-07-09
SCIENCE AND PROGRESS
WHAT THE INVENTIVE MIND IS
DOING FOR HUMANITY.
A Novel Burglar Alarm system.

ANovel Burglar Alarm System.
Electricity is SO mercilessly pressing
the burglar thatit looks as if he would
soon be driven out of business. Doors
and windows are now rendered as SEN
sltlve as electric batterie can make
them, and two methods have been de-
vlsed to prevent a pane of glass being
cut out and an entrance made without
moving the window sash. One is to
sink door spring into the floor I'M
der the carpet directly in front Of the
window, and at night to place a.
chair SO that one leg stands on the
projecting brass rod, forcing it down
and keeping the alarm circuit open un-
TIL some one moves the chair, which
1T would be impossible not to do in
climbing through the windows. An
other, and a very effective way. is to
lay piece of burglar-alarm mating
under the carpet in front of any win
dow to be protected. Burglar-alarm
mating consists OF thin strips
OF wool and springs, so arranged that
any pressure on them closes the
circuit. These mats can be placed on
the stairs or scattered about the
house, and as the carpet covers them
and there is not means of detecting
|, their presence it is nearly an impossi-
bllity for anyone to move about the
house without ringing the alarm, even
II ne could manage to effect an en-
trance. The latest alarm system
makes these various devices active or
imperative by the simple pressure of
button. This operates a drop that
closes the necessary circuits for put
ting the whole system of alarms in
working order for the night. After
this has been done no one can enter
the building, even if the wires leading
to the door and window springs are
in full sight. There is also a Silent
alarm connected to the police station,
but should this circuit become broken
or cut an audible alarm on the out
side of the building still insures pro-
lection. This alarm is so arranged
that it will ring if tampered with from
the outside. Verify, the cracksman
hath fallen on evil days.
The Portelectric System of Trans
portation.
Much significance attaches to the
recent trials OF the portelectric
mode OF rapid freight transmission.
This is an electric automatic sys-
tenn specially designed for carry
ing on and maintaining communi-
cation between cities for the trans
mission OF mail and express matter at
high rate of speed, probably at about
100 miles an hour. Prof. Dolbear's in
designations show that the system is
thoroughly practicable and reliable,
both as regards speed and steady work.
The actual cost OF the electric power
required to propel the carrier at this
rate is not more than 5 cents per
horse.po an hour, includingcost of
attendance at stations. The mere
cost of power for lropelling a carrier
from Boston to New York would,
therefore, not exceed IS cents per trip.
Excessive estimates of the cost
OF a double-track line, making
liberal allowance for all contingencies,
do not exceed $4,000 per mile, or
about 100000 for line between
Boston and New York. The track
consists OF an upper and lower rail
fastened by countersunk screws to
stringers. The carrier is q hollow
cylindrical projectile of wrought iron
with pointed ends. 1t is ten feet in
diameter and has an extreme length
OF twelve feet. 1t weighs obout 500
pounds and contains, say, 10000
letters, weighing about It's pounds.
1t is provided with too Hanged wheels
above and two underneath, all OF
which, being fitted with ball bearings,
revolve with very slight friction. The
propelllng power is derived from series
OF hollow coils Of wire Of great
strength, each of which encircles the
track and carrier. A contact wheel
mounted on the carrier and running
in contact with the upper track rail
(which is divided into sections and
utilized as an electric conductor) con-
meets the several coils in succession
with the source of electricity as the
carrier moves forward on the track,
Moist and Dry Heat and Cold.
Aseries ofexperiments has been lately
made by Herr Rubner Archiv fur Hy-
giene, with regard to the familiar fact
that not only dry high temperatures
are more easily borne than moist, but
dry cold causes much less discom-
fort than moist cold. Dogs, fasting
or fed, being observed in an air-calori-
meter, it appeared that, in all cases.
moist air increased the loss of heat
by conduction and radiation. For
every variation Of air-moisture per
cent heat was parted with to the ex-
tent OF O.32 per cent. In a previous
investigation Herr Rubner demonstra-
ed the lessened yield OF water by evap-
GRAFTON from animals whore the air
moisture is increased, involving les
sened lose of heat. Here, then, are
two antagonistic influences. He is
disposed to regard the increased radia-
ton and conduction in moist air as
the primary action, and the diminish
ed evaporation as secondary. The
colder feeling of moist cold than dry
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