The central Presbyterian. [volume] (Richmond, Va.) 1856-1908, 1881-11-23

90P"i oVoiy W TWO electric lamps, each
capable OF emitting light of about 1000
ctndle-power. One OF these lamps was
placed inside glass-house Of 2,3l8 cubic
feet capacity, and the other was sus-
pended at height of II to IA feet over
some sunk greenhouses. The waste steam
OF the engine was condensed in heater
whence the greenhouses take their cir
culatlon supply of hot water, thus saving
the fuel that would otherwise be re.
CURED to heat the stoves The expert
ments were commenced on October %.
1880, and were continued till May 7,
1881.
THE PLAN OF OPERATION.
" The general plan of operation con-
sists in lighting the electric lights at
first at o'clock, and during the short
days at 5 o'clock, every evening except
Sunday, and continuing their action until
dawn. The outside light was protected
by clear glass lantern while the light
inside the house was left naked. In the
earlier experiments, one of my objects
being to ascertain the relative effect of
the light under those two conditions. the
inside light was placed at one side over
the entrance into the house, in front of
metallic reflector, to save the rays that
would otherwise be lost to the plants
within the house. The house was planted
IN the first place with peas, French
beans, wheat, barley, oats, as we'll as with
caulltiowers strawberries, raspberries.
peaches, tomatoes, vines, and a variety
of Towering plants, including roses,
rhododendrons, and azaleas-aIl these
plants being of comparatively hardy
character. The temperature in this
house was maintained as nearly as pos
slble at 60 Fahrenheit The early effects
observed were anything but satisfactory;
while under the influence of the light
suspended in the open air over the sunk
houses the beneficial effects due to the
electric light observed during the pre-
Vlous winter repeated themselves. The
plants IN the house with the nakel
electric light soon manifested withered
appearance. Was this result the effect
OF the naked light, or was it the effect of
the chemical products, heterogeneous com
pounds, and carbolic acid which are pro
duced IN the electric arc? PROCEEDING
on the frst-named assumption, and with
a view of softening the ray of the electric
arc, small Jets OF steam were introduced
INTO the house through tubes drawing
atmospheric air with the steam and pro
duclng the effect of clouds interposing
themselves in an irregular fashion be-
tween the light and the plants. This
treatment was decidedly beneficial to the
plants, although care had to be taken not
to increase the amount of moisture thus
introduced beyond certain limits.
FURTHER EXPERIMENTS.
Being DESTROYS of following up this
inquiry little further, I sowed a por
ton OF ground in the Experimental Con
servatory with mustard and other quick
growing seeds, and divided the field
INTO equal radial portions by means of
framework excluding difused light, but
admitting light at equal distances from
the electric arc. The first section was
under the action of the naked light. the
second was covered with pane Of clear
glass, the third with yellow glass. the
fourth with red, and the fifth with blue
glass. The relative progress of the plants
was noted from day to day, and the diff
terences of effect upon the development
OF the plants was sufficiently striking to
Justify the following conclusions, VIZ.
Under the clear glass the largest amount
OF and most vigorous growth was in
duced; the yellow glass came next in
order, but the plants, though nearly
equal IN size, were greatly inferior in
color and thickness of stem to those
under the clear glass. The red glass
gives rise to lanky growth and yellowish
leaf, while the blue glass produces still
more lanky growth and sickly leaf. The
uncovered compartment showed stunted
growth, with a very dark and partly
shrivelled leaf 1t should be observed
that the electric light was kept on from
5 P. M. till 6 A. M. every night except
Sunday during the experiment which
took place in January, 1881, but that
diffused daylight was not excluded. At
intervals also the circulation of air
through the dividing framework was
provided for. The results are confrma-
tory of those obtained by DIR. J. w.
Draper in his valuable researc hes on
plant life in the solar spectrum in 1843,
which led him to the conclusion, in op-
position to the then prevailing opinion.
that the yellow ray, and not the violet
ray, was most efficacious in promoting
the decomposition of carbonic acid in the
vegetable cell. Having in consequence
Of these preliminary inquiries, determined
to surround the electric arc with q oIeo,