9 
GARDENING AS A SCIENCE. 
No. I.— LIGHT. 
We are not disposed to enter upon this mysterious agent as in any degree 
connected with the science of optics : or at least we shall merely observe that, as 
the sun's rays — the fountain of light — in passing through the glazed roofs of stoves 
or greenhouses, must be opposed, or refracted, that is, bent in proportion to the 
varying slopes of the sashes, it will be apparent to an acute, reflecting observer, 
that the angle of a glazed roof must influence, in a very considerable degree, the 
power of light within the erection. Thus, if any one hold a pane of glass erect in 
his hand, and view through it a luminous object on a right line, exactly opposite to 
the eye, he will perceive that object clear and well-defined. On the other hand, 
if he incline the pane to angles of different degrees, the object will be distorted or 
lost, till at length it will be evident, that as the edges of the pane are brought into the 
direction of the eye and the object, no ray of light, however intense, can pass at all. 
Thus, to arrive at a practical elucidation of the theory of passing light : that 
slope of a roof, which coincides with, and is perpendicular to the sun, at any period 
of the year, admits the greatest volume of direct (unrefracted) light, at that period ; 
therefore, as a medium, an angle of 45 degrees, i. e. amounting to the eighth part of 
a circle, may be considered as the most applicable to the general purposes of plant 
culture. If fruit be the object, the principle admits of much modification. 
Hereupon it will be relevant to cite the opinion of the late Mr. Knight, one of 
the staunchest advocates of the agency of the solar ray upon vegetable organization. 
Viewing the perfect maturation of the fruit, and intensity of flavour, as points of 
the greatest consequence, he endeavoured to give a slope to the different forcing- 
houses, which should be at a right angle with the sun's rays, at the season when the 
fruit was expected to ripen. Thus, in a private letter on the cultivation of tlie 
Persian melons, he observed that " the quantity of fruit must be regulated by the 
extent of foliage presented to the light. One fruit, of 4 lbs. in weight, may be 
allowed to every four square feet of glass."" The slope of Mr. Knight's Persian 
melon house was very trifling, or about 23 degrees, calculating from the ground 
horizontal line, as the base; an angle which corresponds pretty nearly with the 
altitude of the sun at midsummer. Now, tlie melon plant is trained upon a 
trellis under the sashes, a few inches below the glass, thus exposing the upper 
surface of the leaves to the full glare of the sun. 
Geraniums prosper in a blaze of light, provided they be freely supplied with 
fresh air and water during the growing season ; but that season occurs early in the 
spring ; therefore a slope, of 40 degrees from the ground line, (which is equivalent to 
50 degrees, assuming the perpendicular back wall, as a base,) is very suitable 
to them, and to other plants with juicy, semi-succulent stems. 
VOL. X. NO. cix. c 
