“In Egypt there was a field whose ditches were full of pitch and liquid bitumen. Philosophers, who understood the forces of nature, constructed canals which connected places like these with lamps hidden at the bottom of subterranean crypts. These lamps had wicks made of threads that could not burn. By this means the lamp, once lighted, burned eternally, because of the continuous influx of bitumen and the incombustibility of the wick.”
It is possible that it was to an artifice of this same nature that were due some of the numerous perpetual lamps that history has preserved a reminiscence of, such as that which Plutarch saw in the temple of Jupiter Ammon, in Egypt, and that in the temple of Venus, which Saint Augustine could only explain as due to the intervention of demons. But the majority of them owed their peculiarity only to the precautions taken by the priests to feed them without being seen. It was only necessary, in fact, that the wick, which was made of asbestos threads or gold wire, should be kept intact, and that the body of the lamp should communicate with a reservoir placed in a neighboring apartment in such a way that the level of the oil should remain constant. Heron and Philo have left us descriptions of a certain number of arrangements that permitted of accomplishing such an object.
The same authors likewise point out different processes for manufacturing portable lamps in which the oil rises automatically. The most ingenious one is that which is at the present day known under the name of “Heron’s Fountain.”[12]
[12] In 1801, Carcel and Carreau applied Heron’s system to lamps without, perhaps, knowing that they were thus returning to the primitive apparatus.
The following is the Alexandrine engineer’s text:
“Construction of a candelabrum such that upon placing a lamp thereon, there comes up through the handle, when the oil is consumed, any quantity that may be wished, and that, too, without there being any need of placing above it any vessel serving as a reservoir for the oil.
“A hollow candelabra must be made, with a base in the shape of a pyramid. Let Α Β Γ Δ be such pyramidal base, and in this let there be a partition, Ε Ζ. Again, let Η Θ be the stem of the candelabrum, which should also be hollow. Above, let there be placed a vessel, Κ Λ, capable of containing a large quantity of oil. From the partition, Ε Ζ, there starts a tube, Μ Ν, which traverses it and reaches almost to the cover of the vessel, Κ Λ, upon which latter is placed the lamp in such a way as to allow only a passage for the air. Another tube, Ξ Ο, passes through the cover and runs down, on the one hand, to the bottom of the vessel, Κ Λ, in such a way that the liquid may be capable of flowing, and on the other, forms a slight projection on the cover. To this projection there is carefully adjusted another tube, Π, which is provided with a stopper at its upper part, and, traversing the bottom of the lamp and united with it, is wholly inclosed within the interior of the lamp. To the tube, Π, there is soldered another and very fine one which communicates with it and reaches the extremity of the lamp handle. This tube debouches in the latter in such a way that its contents may empty into the lamp, the orifice of which is of the usual size. Under the partition, Ε Ζ, there is soldered a cock that enters the compartment, Γ Δ Ε Ζ, in such a way that when it is open the water from the chamber, Α Β Ε Ζ, may pass into the compartment, Γ Δ Ε Ζ. Through the upper plate, Α Β, there is pierced a small hole, through which the compartment, Α Β Ε Ζ, may be filled with water, the air within escaping through the same aperture.
PLATO’S LAMP