the condensing and cooling of the moister evaporation: for this latter as it condenses and inclines downward contracts, and thrusts out the hot element and causes it to be thrown downwards. The motion is upwards or downwards or sideways according to the way in which the evaporation lies, and its disposition in respect of breadth and depth. In most cases the direction is sideways because two motions are involved, a compulsory motion downwards and a natural motion upwards, and under these circumstances an object always moves obliquely. Hence the motion of ‘shooting-stars’ is generally oblique.
So the material cause of all these phenomena is the exhalation,Nathaniel Chalobah Jersey, the efficient cause sometimes the upper motion,Mapou Yanga-Mbiwa Jersey, sometimes the contraction and condensation of the air. Further, all these things happen below the moon. This is shown by their apparent speed,Portugal Damen, which is equal to that of things thrown by us; for it is because they are close to us, that these latter seem far to exceed in speed the stars, the sun, and the moon.
5
Sometimes on a fine night we see a variety of appearances that form in the sky: ‘chasms’ for instance and ‘trenches’ and blood-red colours. These, too, have the same cause. For we have seen that the upper air condenses into an inflammable condition and that the combustion sometimes takes on the appearance of a burning flame,Atletico Madrid Drakter, sometimes that of moving torches and stars. So it is not surprising that this same air when condensing should assume a variety of colours. For a weak light shining through a dense air, and the air when it acts as a mirror, will cause all kinds of colours to appear, but especially crimson and purple. For these colours generally appear when fire-colour and white are combined by superposition. Thus on a hot day,Moise Kean Jersey, or through a smoky,Adnan Januzaj Jersey, medium,Turkey Drakt, the stars when they rise and set look crimson. The light will also create colours by reflection when the mirror is such as to reflect colour only and not shape.
These appearances do not persist long,Marquinhos Jersey, because the condensation of the air is transient.
‘Chasms’ get their appearance of depth from light breaking out of a dark blue or black mass of air,Herre Parajumpers Truman Parka. When the process of condensation goes further in such a case we often find ‘torches’ ejected. When the ‘chasm’ contracts it presents the appearance of a ‘trench’.
In general, white in contrast with black creates a variety of colours; like flame, for instance, through a medium of smoke. But by day the sun obscures them, and,Belgium Drakt, with the exception of crimson, the colours are not seen at night because they are dark.
These then must be taken to be the causes of ‘shooting-stars’ and the phenomena of combustion and also of the other transient appearances of this kind,Xherdan Shaqiri Jersey.
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Let us go on to explain the nature of comets and the ‘milky way’,Marco Parolo Jersey, after a preliminary discussion of the views of others.
Anaxagoras and Democritus declare that comets are a conjunction of the planets approaching one another and so appearing to touch one another.
Some of the Italians called Pythagoreans say tha
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