"Holophotal Fixed Light varied by Flashes.—Fresnel's double agents are here also dispensed with by the single agency of panels of fixed light apparatus p', p' and cylindrical refractors L', L', alternating with panels of holophotal apparatus p, p, L, L, both of which revolve together round the central burner." —The Encyclopedia Britannica, 1910

Holophotal Light

"Holophotal Fixed Light varied by Flashes.—Fresnel's double agents are here also dispensed with…

The incandescent light bulb is a source of electric light that works by heat driven light emissions. An electric current passes through a thin filament, heating it until it produces light.

The Light Emitting Incandescent Lamp

The incandescent light bulb is a source of electric light that works by heat driven light emissions.…

An illustration of a flash of lightning.

Lightning Strike

An illustration of a flash of lightning.

"Plane mirrors M revolve on an endless chain placed outside of the apparatus and alter the direction of the flashes after they pass into the dark arc on the landward side so as to cause the lenses L, L to repeat their flashes over the seaward are which requires strengthening. The condensing spherical mirror and mirror of unequal areas will also be found applicable in cases where the flashes do not require to sweep over the whole horizon." —The Encyclopedia Britannica, 1910

Repeating Light

"Plane mirrors M revolve on an endless chain placed outside of the apparatus and alter the direction…