Now by this means may be formed of every kind of rays, besides the principal arch, which goes to the formation of the rainbow, other arches within every one of the principal of the same colour, though much more faint; and this for divers successions, as long as these weak lights, which in every arch grow more and more obscure, shall continue visible. Now as the arches produced by each colour will be variously mixed together, the diversity of colours observ’d in these secondary arches may very possibly arise from them.
11. IN the darker colours these arches may reach below the bow, and be seen distinct. In the brighter colours these arches are lost in the inferior part of the principal light of the rainbow; but in all probability they contribute to the red tincture, which the purple of the rainbow usually has, and is most remarkable when these secondary colours appear strongest. However these secondary arches in the brightest colours may possibly extend with a very faint light below the bow, and tinge the purple of these secondary arches with a reddish hue.
12. THE precise distances between the principal arch and these fainter arches depend on the magnitude of the drops, wherein they are formed. To make them any degree separate it is necessary the drop be exceeding small. It is most likely, that they are formed in the vapour of the cloud, which the air being put in motion by the fall of the rain may carry down along with the larger drops; and this may be the reason, why these colours appear under the upper part of the bow only, this vapour not descending very low. As a farther confirmation of this, these colours are seen strongest, when the rain falls from very black clouds, which cause the fiercest rains, by the fall whereof the air will be most agitated.
13. TO the like alternate return of the fits of easy transmission and reflection in the passage of light through the globules of water, which compose the clouds, Sir ISAAC NEWTON ascribes some of those coloured circles, which at times appear about the sun and moon[337].
SIR ~ISAAC NEWTON~ having concluded each of his philosophical treatises with some general reflections, I shall now take leave of my readers with a short account of what he has there delivered. At the end of his mathematical principles of natural philosophy he has given us his thoughts concerning the Deity. Wherein he first observes, that the similitude found in all parts of the universe makes it undoubted, that the whole is governed by one supreme being, to whom the original is owing of the frame of nature, which evidently is the effect of choice and design. He then proceeds briefly to state the best metaphysical notions concerning God. In short, we cannot conceive either of space or time otherwise than as necessarily existing; this Being therefore, on whom all others depend, must certainly exist by the same necessity of nature. Consequently wherever space and time is found, there God must also be. And as it appears impossible to us, that space should be limited, or that time should have had a beginning, the Deity must be both immense and eternal.