Micrographia eBook

This eBook from the Gutenberg Project consists of approximately 539 pages of information about Micrographia.

Micrographia eBook

This eBook from the Gutenberg Project consists of approximately 539 pages of information about Micrographia.
35-105/997 the fourth 35-140/996 and so onward, each equal quantity of Air having its dimensions measured by 35. and some additional number exprest alwayes in the manner of a fraction, whose numerator is alway the number of the place multipli’d by 35. and whose denominator is alwayes the pressure of the Atmosphere sustain’d by that part, so that by this means we may easily calculate the height of 999. divisions of those 1000. divisions, I suppos’d; whereas the uppermost may extend it self more then as high again, nay, perhaps indefinitely, or beyond the Moon; for the Elaters and Expansions being in reciprocal proportions, since we cannot yet find the plus ultra, beyond which the Air will not expand it self, we cannot determine the height of the Air:  for since, as we have shewn, the proportion will be alway as the pressure sustain’d by any part is to 35. so 1000. to the expansion of that part; the multiplication or product therefore of the pressure, and expansion, that is, of the two extream proportionals, being alwayes equal to the product of the means, or 35000. it follows, since that Rectangle or Product may be made up of the multiplication of infinite diversities of numbers, that the height of the Air is also indefinite; for since (as far as I have yet been able to try) the Air seems capable of an indefinite Expansion, the pressure may be decreased in infinitum, and consequently its expansion upwards indefinite also.

There being therefore such a difference of density, and no Experiment yet known to prove a Saltus, or skipping from one degree of rarity to another much differing from it, that is, that an upper part of the Air should so much differ from that immediately subjacent to it, as to make a distinct superficies, such as we observe between the Air and Water, &c.  But it being more likely, that there is a continual increase of rarity in the parts of the Air, the further they are removed from the surface of the Earth:  It will hence necessarily follow, that (as in the Experiment of the salt and fresh Water) the ray of Light passing obliquely through the Air also, which is of very different density, will be continually, and infinitely inflected, or bended, from a streight, or direct motion.

This granted, the reason of all the above recited Phaenomena, concerning the appearance of the Celestial Bodies, will very easily be deduced.  As,

First, The redness of the Sun, Moon, and Stars, will be found to be caused by the inflection of the rays within the Atmosphere.  That it is not really in or near the luminous bodies, will, I suppose, be very easily granted, seeing that this redness is observable in several places differing in Longitude, to be at the same time different, the setting and rising Sun of all parts being for the most part red: 

And secondly, That it is not meerly the colour of the Air interpos’d, will, I suppose, without much more difficulty be yielded, seeing that we may observe a very great interstitium of Air betwixt the Object, and the Eye, makes it appear of a dead blew, far enough differing from a red, or yellow.

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Micrographia from Project Gutenberg. Public domain.