Micrographia Part 26

_The exceeding smalness of some Mites, and their Eggs. A description of the Mites of Cheese: and an intimation of the variety of forms in other Mites, with a Conjecture at the reason._

Ob. 56. Of small Vine-Mites.

_A description of them; a ghess at their original; their exceeding smalness compar'd with that of a Wood-louse, from which they may be suppos'd to come._

Observ. 57. Of Vinegar-worms.

_A description of them, with some considerations on their motions._

Obs. 58. Of the Inflexion of the Rays of Light in the Air.

_A short rehearsal of several _Phaenomena_. An attempt to explicate them: the supposition founded on two Propositions, both which are indeavoured to be made out by several Experiments, What density and rarity is in respect of refraction: the refraction of Spirit of Wine compared with that of common Water: the refraction of Ice. An Experiment of making an Undulation of the Rays by the mixing of Liquors of differing density. The explication of _inflection_, mechanically and hypothetically: what Bodies have such an inflection. Several Experiments to shew that the Air has this propriety; that it proceeds from the differing density of the Air: that the upper and under part of the Air are of differing density: some Experiments to prove this. A Table of the strength of the spring of the Air, answering to each degree of extension; when first made, and when repeated. Another Experiment of compressing the Air. A Table of the strength of the Air, answering to each compression and expansion; from which the height of the Air may be suppos'd indefinite; to what degree the Air is rarifi'd at any distance above the Surface of the Earth: how, from this, Inflection is inferr'd; and several _Phaenomena_ explain'd. That the Air near the Earth is compos'd of parts of differing density; made probable by several Experiments and Observations; how this propriety produces the effects of the waving and dancing of Bodies; and of the twinkling of the Stars. Several _Phaenomena_ explicated. Some Quaeries added._

1. _Whether this Principle may not be made use of, for perfecting Optick Gla.s.ses? What might be hoped from it if it were to be done?_

2. _Whether from this Principle the apparition of some new Stars may not be explicated?_

3. _Whether the height of the Air may be defin'd by it?_

4. _Whether there may not sometimes be so great a disparity of density between the upper and under parts of the Air, as to make a reflecting Surface?_

5. _Whether, if so, this will not explicate the _Phaenomena_ of the Clouds.

An Experiment to this purpose?_

7. _Whether the Rayes from the top of Mountains are not bended into Curve-lines by inflection? An Argument for it, taken from an Experiment made on St. _Paul_'s Steeple._

8. _Whether the distance of the Planets will not be more difficult to be found? What wayes are most likely to rectifie the distance of the Moon: the way of fitting _Telescopes_ for such Observations. How to make the Observations, and how from them to find the true distance of the Moon at any time. How the distance of the Sun may be found by two Observators. The way by the Dicotomy of the Moon uncertain. That the distance of the Moon may be less then it has been hitherto suppos'd. _Kepler_'s Supposition not so probable: the explication of the _Phaenomena_ by another _Hypothesis_._

Observ. 59. Of the fixt Stars.

_Of the mult.i.tudes of Stars discoverable by the _Telescope_, and the variety of their magnitudes: 78. Stars distinguisht in the _Pleiades_: that there are degrees of bigness even in the Stars accounted of the same magnitude: the longer the Gla.s.ses are, and the bigger apertures they will indure, the more fit they are for these discoveries: that 'tis probable, longer Gla.s.ses would yet make greater discoveries. 5. Stars discover'd in the _Galaxie_ of _Orion_'s Sword._

Observ. 60. Of the Moon.

_A description of a Vale in the Moon; what call'd by _Hevelius_ and _Ricciolus_, and how describ'd by them: with what substances the hills of the Moon may be cover'd. A description of the pits of the Moon, and a conjecture at their cause: two Experiments that make it probable, that of the surface of boyl'd Alabaster dust seeming the most likely to be resembled by eruptions of vapours out of the body of the Moon: that Earthquakes seem to be generated much the same way, and their effects seem very similar. An Argument that there may be such variations in the Moon, because greater have been observ'd in the Sun: because substance of the Moon and Earth seem much alike: and because 'tis probable the Moon has a gravitating principle: this is argued from several particulars. The reason why several pits are one within another. The use that may be made of this Instance of a gravity in the Moon._

[1] _Schem._ 2. _Fig._ 1.

[2] Diop. ch. 10. -- 9.

[3] _Schem._ 2. _Fig._ 2.

[4] _Schem._ 1.* _Fig._ 3.

[5] _Schem._ 3. _Fig._ 1.

[6] _Schem._ 3. _Fig._ 2.

[7] _Schem._ 4.

[8] _Schem._ 4. _Fig._ 1.

[9] _Schem._ 6. _Fig._ 3.

[10] _Schem._ 6. _Fig._ 3.

[11] _Schem._ 8. _Fig._ 1.

[12] _Schem._ 8. _Fig._ 2.

[13] _Schem._ 9. _Fig._ 1.

[14] See _Schem._ 11. _Fig._ 2.

[15] _Fig._ 1. _Schem._ 36.

[16] _Fig._ 3.