Sig′nal-light.
A form of signal-light to be thrown into the water to direct attention of a man overboard, and of rescuing boats, consists of a tin cylinder with conical top, and a float by which it is sustained vertically in the water.
The case is charged with phosphide of calcium, secured air-tight therein.
For use, the top of the cylinder is cut off and the bottom end of the tube opened, so that water can enter, and evolve gas from the compound, which inflames as soon as it comes in contact with the air.
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Signal-light. |
In
Fig. 5083,
A B are side and end elevations of
Cooke's apparatus for displaying the electric light from the clocktower of the
Parliament Houses at
Westminster.
t t′ are two screws which receive the terminals of the battery-wires, from whence the positive and negative currents are conducted respectively to the hinges
h h′ of the stand, and thence to the studs
i i′ which transmit it to the carbon points in the regulators
l l′; these are fixed upon a board
r, which slides upon the table
p, and each carries two copper strips, which make connection with the studs
i i′, when either lamp is in proper position; when the carbon points of one lamp are near consumed, as
l for example, it may be pushed over, so that
l′ occupies its place, the interruption of light being only instantaneous; fresh points are then placed in
l, which in its turn replaces
l′, the light being thus rendered practically continuous for as long a time as necessary.
By means of the elevating-screw
f and hand-wheel
e having a worm gearing with teeth around the periphery of the table
c, the light, transmitted through a Fresnel lens
m, may be thrown in any desired direction, either in altitude or azimuth.
