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foot candles. The Joint Committee on School Lighting recommended
a minimum of two foot candles. My reason for specifying
3.5 was partly due to the number of eye defects in the
school, and partly due to the class of children attending that
school, in addition to which due allowance must be made for
depreciation owing to the wear in the mantles.
In order to find the best position for the lights which
would give a left lateral light with even distribution in the
room, the Gas Company put in several experimental installations
and the final position of the lights are shown on the
accompanying diagrams.
Room 5 in the Girls' Department is a large room, 29ft.
6in. by 20ft., containing two classes. The lamps were placed
at slightly different heights, and with the positions shown on
the diagram one was able to obtain a minimum of four foot
candles in the furthest corner of the room. The light in this
case is extremely satisfactory, free from shadow, and on the
whole rather higher than is necessary. In this room the old
burners consumed 40 cu. ft. of gas per hour the new installation
gives nine or ten times the light with a consumption of
48 cu. ft. per hour.
In room 5 in the Infants' Department which is 23ft. 9in.
by 20ft. more use was made of the reflecting surface of the
walls and the lights placed only one foot from the left-hand
wall so that again there is in this case left lateral lighting
with freedom from shadow. The figures in this case show the
lighting with the old and new installations as measured by the
lumeter. It will be seen that in this case with the old burners
the maximum light was .2G foot candles with a consumption
of 40 cu. ft. per hour, whereas the new installation gives a
minimum of 3.5 foot candles with a consumption of 24 cu. ft.
per hour. In Room 6, eight lamps were installed of approximately
50 candle power each and consuming 2'5 cu. ft. per
hour, but this installation was unsatisfactory, as owing to
the smaller candle power it was necessary to bring the lights
nearer to the desks, and, although the distribution of the lights
was even, awkward shadows were produced. The various
positions and characters of the lights were only arrived at
after numerous experiments with different globes and burners
and alterations in their positions, and numerous measurements
with the lumeter. In Room 5 in the Infants' Department it
was estimated that to produce the same illumination by electric
light, that is, a minimum of 3.5 foot candles at the necessary
distance, would have cost almost threepence per hour,
whereas the cost of gas worked out at just over three-farthings
per hour.
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