Blackfoot news. (Blackfoot, Idaho) 1891-1902, 1893-12-30

with a platinum point This needle
is connected by wire with a pedal,
p, situated upon the track. On
another hand, the axis, E, of the
cylinder is in communication with the
negative pole of the battery, 2, of
which the positive pole is connected
with the lower part of the pedal.
When the train passes, its weight de-
presses the pedal, the circuit is closed,
the iodide of potassium is decomposed
at the point where the needle touches
the paper. and the iodide set at liberty
is shown by black dot.
Upon the length of a section, a
pedal may be arranged about every
mile. Each is connected by special
wire with a needle of the watch tower.
and all these needles are arranged
along a generatriX of the registering
cylinder. When train passes over a
pedal, the corresponding needle, which
carries number reproduced upon the
pedal, marks a black dot upon the
paper. At every instant the employe
knows, then, over what pedal the
train has Just passed. He sees whether
an express train Is upon the point of
telescoping an excursion one, whether
two trains running in different direc-
tions upon the same track are about to
meet. etc, and he prevents such catas-
throphes, since he can forewarn the
engineers of the trains In fact. in
the center of the interval compr sed
between two pedals there is what is
called contact apparatus. This con
sists of a metallic drum about eighty
centimeters in diameter ana twenty in
height. The locomotive carries a
metallic brush, which, at the moment
r 4.
drum to revolve. This drum is pro-
teeted against rain, snow and frcst by
q galvanized iron box, but at the two
eXtremities of the same diameter. IA
Zig. 81, it projects from the box.
These are the parts that the brush
tou hes. AS this latter is very long
as metersl il is capable of establish
ing metallic communication with the
drum, even If the unprotected parts of
the latter are covered with frost, since
it makes them revolye.
In the watchtower there are ar
ranged in a row, like the keys of pi-
ano, q series of eommutators, each of
which carries two numbers, those of
the pedals between which is situated
the drum with which the commut tor
enters into relation. When the em-
ploye puts his finger upon commuta-
tor, battery actual relav, which
serves to put the rail in communica-
tion with the drum. The brush of the
locomotive, electrically insulated from
the general metallic mass of the en-
CINE, communicates with one of the
wire of Hughes electro magnet. the
other extr nifty OF which is connected,
through the inlermedium of a battery
carried by the locomotive, with the
latter and the rail. Consequently,
there is a closed circuit when drum
Is in contact with the brush. AT this
moment the electro-magnet is freed,
and this sets in action steam whistle,
the sound of which warns the eng,-
neer.
1t will be seen that the engineer
does not have to oh erve at a distance
optical signals which fog, for example,
may render difficult e. see. Heis fore
warned by shrill sound that makes
itself heard upon his engine and he
is so much the better warned in that
the noise of the whistle continues so
long as he has not himself closed the
armature OF the electromagnetic by
hand. II viii be seen that il is very
difficult fot him not to take notice OF
this sirnal