Speculum mundi· Or A glasse representing the face of the world shewing both that it did begin, and must also end: the manner how, and time when, being largely examined. Whereunto is joyned an hexameron, or a serious discourse of the causes, continuance, and qualities of things in nature; occasioned as matter pertinent to the work done in the six dayes of the worlds creation.

Artic. I. Of Clouds.

I Begin therefore with clouds. And a cloud is a vapour or Exhalation cold and moist, drawn from the earth out of wet or watery places, by heat of the Sunne, into the middle Region of the aire; where by cold it is so thickened and knit together, that it hangeth, untill either a 1.1 the own weight, or some resolution, causeth it to fall. If it be a great cloud, it is Nubes; if it be but a little one, it is called Nubecula. The name comes ab obnubendo, id est, operiendo coelum, from hiding or covering the heavens: be∣cause a cloud (through the thicknesse that the vapour is condensed into) hindereth, that a lesse portion of the hea∣vens is conspicuous, then otherwise would be.

It is also two-fold; either fertill, or barren.

A fertill or fruitfull cloud affordeth rain: but a barren cloud doth not; because it is at length by the blasts of winde, and vertue of the heavenly bodies, turned into thin aire.

And to either of these clouds belong motion & colour.

Their motion is caused by the winde most commonly, through whose force they are driven to and fro: But if the windes blow not, then they are drawn along by the Sun, and made a companion with him in his travels, alwayes moving that way which the Sunne goeth.

Concerning their colours I spake before in Para∣graph 5. Article 2. And therefore here you may expect the lesse: yet let me say that they are either simple or mixt.

Black or white are simple; because they consist of no other colours. But red, green, and the rest, are mixt.

They appeare white when the vapour is thin; for then it is easily pierced by the light, which disperseth it self into it.

But when they appeare of a b 1.2 black colour, then the vapour is thick, and more closely condensed: in∣somuch that the beams of light cannot be admitted▪

As for their rednesse, it may be caused two wayes, according to Goclenius: either through the adustion of the aire, magno aestu incensum, as he saith: Or propter retusum radium Solis, by reason of the beams of the Sunne beat back again; which, falling upon a watery cloud that is thickly condensed, pierceth not; but being doubled cau∣seth rednesse, as in the morning: and this is a signe of rain: but the other is not. For the other rednesse is in such a cloud as sheweth the drinesse and adustion of the aire; the cloud it self consisting of a smokie humid substance, unto which is joyned a kinde of drie and adust matter. This therefore is a signe of c 1.3 fair weather, being seen in the evening towards the place of Sun-setting; according as it hath been said of old, Serò rubens coelum, mané indicat esse serenum.

Concerning green clouds they are altogether watery, and as it were already resolved into water; which recei∣ving into them the light appeare green, like unto water in a great vessel, or in the sea and deep rivers.

Blew clouds come something neare to the nature of black, excepting that the black are thicker.

And note, If when the Sunne sets, there appeare or arise black dark clouds, it portendeth rain. Also observe the place opposite to the Sunne at his setting, viz. the East, and see if that be cleare: for if it be pestered with black clouds, there is but small hope of fair weather that night, or the next day.

The common opinion is, that the height of the clouds* 1.4 is not above nine miles. But it is agreeable to no reason

at all why any certain height should be determined: for they are of unequall heights, differing both according to the matter of their composure, and also according to the time of the yeare; being lower in winter then in summer: for when the sunne hath the greatest force they then ascend the higher; and in his smaller force they hang the lower. By which it appeareth that the sunne helpeth to uphold them, and keepeth them (al∣though heavier then the aire) even in the aire: for they▪ sometimes also follow his motion.

But note that it is not the sunne alone which upholds* 1.5 them; for the aire it self is also a cause of their not fall∣ing; and that both within the clouds, and also without them: within the clouds; for the clouds are of a spungie nature, and full of pores, which are filled with aire le•…•…t there should be vacuum; and this aire heaveth them up, causing them to aspire: without the clouds also, because they do as it were float up and down in the aire, as some heavie things do in the water, and yet not sink, unlesse their substance be too earthie and heavie.

Notes

• a 1.1

  It is said that clouds have sometimes fallen down to the earth with great noise, to the te•…•…rour & damage of such as had them in their Zenith, which clouds came but from the highest part of the lowest region: yet never∣thelesse they were generated in the middle Region, but waxing very heavie have sunk down by little and little, till at last they seem to fall no further then the lowest Region: But this is seldome. They may also fall by drops through their own weight.
• b 1.2

  Nigredo in nubi∣bus ob vaporum densitatem oritur, qu•…•… lumen collu∣strans non admittit. Et sic é contrá •…•…it Albor; viz. è va∣pore subtiliore & parùm conspissato, quem radius facil∣limé pe•…•…etrat, & •…•…quabiliter in illum spa•…•…gitur. Goclen. Dis•…•…us. Phys.
• c 1.3

  〈◊〉〈◊〉 rubedo 〈◊〉〈◊〉 signifi∣cat, quia▪ rubedo nu∣bem rara•…•…t est•…•… so∣lis 〈◊〉〈◊〉, ejús∣que 〈◊〉〈◊〉 ab∣•…•… esse •…•…∣tat. Sed 〈◊〉〈◊〉 rubedo plu•…•…ias 〈◊〉〈◊〉 ventos promi•…•…tit, quia vapores humi∣darum & sub densa∣rum 〈◊〉〈◊〉 absu∣mi non 〈◊〉〈◊〉. Ibid.
• * 1.4

  The height of the clouds.
• * 1.5

  How the clouds naturally hang in the aire.