174 
THE FLORAL WORLD AND GARDEN GUIDE. 
task is to colour it correctly. The real rainbow consists of many 
more shades of colour than have ever been counted, because all the 
colours are in transition, the central band of each being most pure 
and intense, and thence each way it shades by fine degrees into the 
colour that adjoins it. This fine shading could not, it need hardly 
be said, be imitated with bedding-plants, and we must take for the 
basis of operations the popular doctrine that the rainbow consists 
of seven colours only. Having determined this point it follows 
that we must settle the relative proportion of these colours. In 
the real rainbow they are disposed in the following order : — 1, red, 
45 parts; 2, orange, 27 parts; 3, yellow, 48 parts; 4, green, 60 
parts ; 5, blue, 60 parts ; 6, indigo, 40 parts ; 7, violet, 80 parts, in 
all 360, the breadth of the bow. 
Now supposing we have to adopt the same proportions and con- 
sider all the figures as inches, thus then the bow is to be 360 inches 
or 30 feet wide. On this scale the space necessary would be very 
great and the number of plants required simply enormous. It will 
be necessary to have the bow considerably broader in proportion to 
the length of the chord than is the natural bow, for the simple 
reason that as we cannot plant ribbon-lines from horizon to 
horizon we cannot give it breadth enough to be visible and practic- 
able unless we depart from the scale on which the bow is produced 
naturally. 
From calculations carefully made it appears that* the following 
are good proportions ; that is to say, proportions to which the 
planter can adapt his work without difficulty, and proportions 
which are likely to prove satisfactory when view'ed in a garden scene. 
For a quarter-inch scale the bow will be 7| feet wide, and the chord 
will be 105 feet in length, measuring from violet to violet, or 120 
feet from red to red. By drawing a bow with the aid of pencil and 
compasses exactly to these proportions, it will be seen how admirably 
it is adapted for forming a ribbon boundary to a semicircular lawn 
in front of a house, or to give a semicircular outline to a lawn facing 
the drawirg-room windows where there happens to be clear space 
enough for drawing it complete without trees and shrubs interfering. 
A very good scale would be three-eighths, this would give 11 1 feet 
for the breadth of the bow, that is from red to violet, and 180 feet 
for the length of the chord from red to red ; to carry it out the 
inner and outer boundaries should both be struck from the same 
centre, and when the bow is cut the breadths for the several 
colours should be marked off with pegs, and these pegs left in the 
ground, so that at any time they could be referred to to see if any 
one colour was encroaching too much on another. 
Supposing that we have the bow marked out, it is necessary to 
at once consider what we are to plant it with. As it is practically 
impossible to provide the blue ground, for on the lawn there is 
not room for it, we must consider the planting in relation to a 
green ground. Even with the greater abundance of material at the 
present moment it requires a considerable amount of care and 
knowledge of bedding-plants generally to select them without 
incurring a risk of failure. It is of the first importance that for 
