h noisy puff of smoke a
quantity of air is forcibly drawn into the fire-box through the burning
fuel. In the modern oil-lamp the rush of air due to the "pull" of the
chimney is broken and the air is diffused by the wire gauze or holes at
the base of the burner. These metal parts, being hot, also serve to warm
the oil before it reaches the burning end of the wick, thus serving to
aid vaporization and combustion.

The consumption of oil per candle-power per hour varies considerably
with the kind of lamp and with the character of the oil. The average
consumption of oil-lamps burning a mineral oil of about 0.80 specific
gravity and a rather high flashing-point is about 50 to 60 grams of oil
per candle-power per hour for well-designed flame-lamps. Kerosene weighs
about 6.6 pounds per gallon; therefore, about 800 candle-power hours per
gallon are obtained from modern lamps employing wicks. Kerosene lamps
are usually of 10 to 20 candle-power, although they are made up to 100
candle-power. These luminous intensities refer to the maximum horizontal
candle-power. The best practice now deals with the total light output,
which is expressed in lumens, and on this basis a consumption of one
gallon of kerosene per hour would yield about 8000 lumens.

Oil-lamps have been devised in which the oil is burned as a spray
ejected by air-pressure. These burn with a large flame; however, a
serious feature is the escape of considerable oil which is not burned.
These lamps are used in industrial lighting, especially outdoors, and
possess the advantage of consuming low-grade oils. They produce about
700 to 800 candle-power hours per gallon of oil. Lamps of this type of
the larger sizes burn with vertical flames two or three feet high. The
oil is heated as it approaches the nozzle and is fairly well vaporized
on emerging into the air. The names of Lucigen, Wells, Doty, and others
are associated with this type of lamp or torch, which is a step in the
direction of air-gas lighting.

During the latter part of the nineteenth century numerous developments
were made which paralleled the progress in gas-lighting. Experiments
were conducted which bordered closely upon the next epochal event in
light-production--the appearance of the gas mantle. One of these was the
use of platinum gauze by Kitson. He produced an apparatus similar to the
oil-spray lamp, on a small and more delicate scale. The hot blue flame
was not very luminous and he attempted to obtai