52 
THE FLORIST’S JOURNAL. 
by any of them. The effect of this may be seen by a very simple 
experiment : — let there be two red roses upon the same thickly- 
leaved and healthy tree, both equally expanded and equally beau¬ 
tiful. Pull one without leaves, lay it on the gravel walk, stand 
equally distant from the two, and half the beauty of that on the 
walk will be gone. Remove it to the grass-plat, and its beauty 
will return, though not to the same extent as it had when on the 
tree, clearly showing that the beauty of a rose is best set off by its 
own leaves ; and the same holds true in the case of every other 
flower. This gives us a useful hint for our arrangement; — we 
must study not merely the contrasts of flowers, but the contrasts 
of entire plants, both flower and leaf, in order that the resulting 
beauty may be the greatest possible. 
Such are the colours into which light is resolved by one simple 
decomposition, and such the extents which they severally occupy 
in the spectrum ; but before we can fully understand the principle 
of their most advantageous contrasts, we have two considerations 
to take into account,—the absolute or mathematical contrast of 
the colours, and the sensal contrast as they affect the eye. The 
first of these is a matter of experiment; and the second is a matter 
of observation, — and though the same in kind in all human eyes, 
it is probably not the same in degree in any two persons. 
With regard to the composition, it will be seen that the sum of 
the above numerical portions of the spectrum occupied by the 
seven colours, answers exactly to the 360 degrees into which 
mathematicians divide the circumference of a circle. Therefore, if 
a circular board, fixed to an axis, is taken, and painted, or covered 
with paper, in the order, proportion, and tint, of the seven colours, 
each colour occupying a sector, extending from the centre, and 
extending as many degrees on the circumference as its number of 
parts in a spectrum, this circular board, upon being turned rapidly 
round, will appear altogether of a pure white colour; proving 
that it contains the coloured elements of white light in their due 
proportions. If one colour is omitted, and pure black substi¬ 
tuted in its place, the colour of the revolving board will not be 
white, but the complement of the colour which is omitted. As, 
for instance, if the red is omitted, the colour of the revolving 
board will be green ; if the yellow, it will be blue ; if the green, 
it will be purple ; and if the blue, it will be red. There is 
another and an easier method of finding out the complemental 
