Or thus; It is a bow of many colours, appearing in a dewie, dark, droppie, and hollow cloud, by reflection of the Sunne-beams opposite to it. For this is certain, that lightsome or luminous bodies do cause images, colours, or appearances upon slender, clean, and thin objects: Now of all bodies the Sunne is most lightsome; but the aire and water are clean, thin, and slender.
Here then it appeareth that the Efficient cause of the Rain-bow is the light or beams of the Sunne; which fall∣ing into fit, apt, or convenient matter, opposite to them, are refracted and reflected to our sight.
The Materiall cause is not water in act, nor yet thick aire, but a dewie vapour; which is not conti∣nuus, sed potiùs corpusculis guttularum discretus; not abso∣lutely of one bodie, but rather severed into many bodies, or little drops.
The Form of it is to be gathered out of the Figure and Colours.
And for the Figure, we see it is circular: But yet it never representeth to us any more then a Semicircle; and not alwayes so great an arch: The reason of which is, be∣cause the centre or middle point of the Rain-bow, which is diametrally opposite to the centre of the Sunne, is alwayes either in the Horizon, or under it: So that seeing our sight of the heavens is cut off by the earth in such a manner as that we can never see above half of them, it must needs be, that the appearance of this circle be either more or lesse to us, according to the Sunnes great or little distance from the Horizon.
And as for the colours, they are commonly accounted three, viz. Ruddie, Green, and Azure. To which some adde a fourth. The first is in the thickest and darkest part of the cloud: For where a bright shining falleth upon a darkish place, there it representeth a ruddie colour, being somewhat like a Flame. The second is caused by a more