about 20 per cent. more light than that given by the standard spermaceti
candle, whose luminosity is the unit by which the intensity of other
lights is reckoned in Great Britain; and also that the light so emitted
by domestic candles is practically unaffected by the sizes--"sixes,"
"eights," or "twelves"--burnt. In the sizes examined the light evolved
has varied between 1.145 and 1.298 "candles," perhaps tending to increase
slightly with the diameter of the candle tested. Hence, to obtain
illumination in a room equal on the average to that afforded by 100
standard candles, or some other light or lights aggregating 100 candle-
power, would require the use of only 80 to 85 ordinary paraffin,
ozokerite, or wax candles. But actually the essential objects in a room
could be equally well illuminated by, say, 30 candles well distributed,
as by two or three incandescent gas-burners, or four or five large oil-
lamps. Lights of high intensity, such as powerful gas-burners or oil-
lamps, must give a higher degree of illumination in their immediate
vicinity than is really necessary, if they are to illuminate adequately
the more distant objects. The dissemination and diffusion of their light
can be greatly aided by suitable colouring of ceilings, walls and
drapings; but unless the illumination by means of lights of relatively
high intensity is made almost wholly indirect, candles or other lights of
low intensity, such as small electric glow-lamps, can, by proper
distribution, be made to give more uniform or more suitably apportioned
illumination. In this respect candles have an economical and, in some
measure, a material advantage over acetylene also. (But when the method
of lighting is by flames--candle or other--the multiplication of the
number of units which is involved when they are of low intensity,
seriously increases the risk of fire through accidental contact of
inflammable material with any one of the flames. This risk is much
greater with naked flames, such as candles, than with, say, inverted
incandescent gas flames, which are to all intents and purposes fully