coal trade bulletin - Clpdigital.org

44 THE COAL TRADE BULLETIN.
protected so that it is almost impossible to break
it.
The electrolyte of the battery must not leak out.
That constructions of this character are possible,
and in actual use, will be shown later on.
During the year 1912 prizes were offered by the
British government for the best portable electric
mine lamp and not less than 197 applicants entered
into competition and submitted samples.
After careful tests extending over several months,
the first prize of $3,000 was awarded to the makers
of the "Ceag" lamp described in this paper.
Since this lamp has also been accepted by practically
all otlier European governments and was the
first lamp approved by the Bureau of Mines, answering
all requirements, and still remains today
the only approved hand lamp, it might be well to
study its construction carefully.
The incandescent lamp is covered by a heavyglass
dome, which is protected by four heavy steel
l ods held together by a sheet steel roof. A substantial
hook is attached to this roof, so that the
miner ean either stand the lamp on the ground or
hang it to a post in the
IM .MEDIATE NEIGHBORHOOD
of his working place. The bottom part, made of
heavy corrugated galvanized sheet steel, contains
the storage battery. By turning the upper part
on the lower, the miner can turn the light on and
off.
The incandescent lamp rests in a socket, which
is pressed upward by a spiral spring against another
spring between the bulb and glass dome,
providing a complete spring support and preventing
breakage even with the most severe shocks.
Electric connection is established for one pole
through the socket spring, and for the other pole
by another smaller spring inside the socket
spring, and insulated from it. In case the bulb
breaks, the socket spring pushes the socket upwards,
and as the inner spring does not expand as
much as the socket spring, the circuit is interrupted.
Lately, another safety device has been added.
It consists of a fuse, which blows the moment the
bulb of the incandescent lamp is broken. This
eliminates the possibility of obtaining sparks or
getting the filament to glow in case the miner
should attempt to push the bulb back into its
normal position; it also protects the battery from
being short-circuited for any length of time, in
case the leads to the bulb have become short-circuited
during the accident.
As stated before, the upper part of the lamp
turns on the lower part, opening and closing the
switch. This rotating movement is limited by a
soft iron pin, which acts as a magnetic lock.
This pin can be withdrawn in the charging room
by a strong electromagnet, and when this is done,
the upper and lower parts of the housing separate,
and the battery can be removed for charging.
The storage battery consists of a single round
lead cell with concentric electrodes inside of a
celluloid vessel covered with a waterproof lid of
the same material. Cylindrical electrodes were
given the preference over flat ones, as they are
stronger and therefore
STAND ROUGHER HAXDLIXG.
They also warp less, so that in charging, the current
density can be increased and the length of
time correspondingly decreased. The holes in
the terminal sockets contain bushings made of
acid-proof metal, into which removable terminals,
are fitted. These terminals are pressed upward
by the terminal springs and against the contact
segments of the switch, carrying in this manner
the current to the incandescent lamp. Terminals
and springs can easily be taken out and cleaned
by washing in warm water, a very important
point. The use of non-removable springs has
been found impractical, as they are very difficult
to clean, consequently are liable to corrode and
break easily. First-class contact springs, however,
are imperative for an uninterrupted light
service.
In charging storage batteries gases develop,
which must have an opportunity to escape. It is
therefore impossible to make the cells airtight.
An ordinary opening, on the other hand, would
have the disadvantage that the acid would run
out, in case a cell were upset, and this would destroy
the housing of the lamp. In order to overcome
this difficulty, the center of the cell is equipped
with a celluloid tubing which is in communication
with the upper part of the cell, where all
gases collect, by means of a small side tubing.
The gases therefore can pass from the cell through
the side tubing and finally through center tubing
into the open, whereas any particles of acid carried
along by the gases, will deposit in cylinder
Even if the cell is turned upside down, no acid
which may be in cylinder or any other acid, can
escape. In other words, the lamp will burn in
any position, without the acid being able to leak
out.
The principal dimensions of this lamp are as
follows: The weight of the lamp complete is
about 5 pounds (2.4 kg.); its height, not including
hanger, is 10% inches (26 cm.); its largest
diameter is Z r -:L inches (9.5 cm.) The incandescent
lamp consumes 0.85 amperes at 2 volts. The
battery has a capacity of 16 ampere-hours, and
the maximum charging current should not exceed
2 amperes.
To meet various requirements this standard design
is not only made in