The hen, when permitted to follow her natural course, rises with the sun and goes to roost at sunset.  During the winter months she puts in short days off the roost.  It has been shown that an artificial day, made by piecing out daylight by means of artificial light, might keep the hen scratching and feeding longer, with an increased production of eggs as a result.  Many experiments of this character have been carried out, and there appears to be a general conclusion that the use of artificial light for this purpose is profitable.

Experiments conducted recently by the agricultural department of a large university indicate that in poultry husbandry, when artificial light is applied to the right kind of stock with correct methods of feeding, the distribution of egg-production throughout the whole year can be radically changed.  The supply of eggs may be increased in autumn and winter and decreased in spring and summer.  Data on the amount of illumination have not been published, but it is said that the most satisfactory results have been obtained when the artificial illumination is used from sunset until about 9 P. M. throughout the year.

An increase of 30 to 40 per cent. in the number of eggs laid on a poultry-farm in England as the result of installing electric lamps in the hen-houses was reported in 1913.  On this farm there were nearly 200 yards of hen-houses containing about 6000 hens, and the runs were lighted on dark mornings and early nights of the year preceding the report.  About 300 small lamps varying from 8 to 32 candle-power were used in the houses.  It was found that an imitation of sunset was necessary by switching off the 32 candle-power lamps at 6 P. M. and the 16 candle-power lamps at 9:30.  This left only the 8 candle-power lamps burning, and in the faint illumination the hens sought the roosting-places.  At 10 P. M. the remaining lights were extinguished.  It was found that if all the lights were extinguished suddenly the fowls went to sleep on the ground and thus became a prey to parasites.  The increase in production of eggs is brought about merely by keeping the fowls awake longer.  On the same farm the growth of chicks incubated during the winter months increased by one third through the use of electric light which kept them feeding longer.

Many fishermen will testify that artificial light seems to attract fish, and various reports have been circulated regarding the efficacy of using artificial light for this purpose on a commercial scale.  One report which bears the earmarks of authenticity is from Italy, where it is said that electric lights were successfully used as “bait” to augment the supply of fish during the war.  The lamps were submerged to a considerable depth and the fish were attracted in such large numbers that the use of artificial light was profitable.  The claims made were that the supply of fish was not only increased by night fishing but that a number of fishermen were thereby released for national service during the war.  An interesting incident pertaining to fish, but perhaps not an important factor in production, is the use of electric lights in the summer over the reservoirs of a fish hatchery.  These lights, which hang low, attract myriads of bugs, many of which fall in the water and furnish natural and inexpensive food for the fish.