Page:Micrographia - or some physiological descriptions of minute bodies made by magnifying glasses with observations and inquiries thereupon.djvu/373

Rh 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 Phænomena 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 Phænomena explicated. Some Quæries added. 1. Whether this Principle may not be made use of, for perfecting Optick ''Glasses? 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 Phænomena 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 Phænomena by another Hypothesis.

Observ. 59.Of the fixt Stars.

Of the multitudes 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 Glasses are, and the bigger apertures they will indure, the more fit they are for these discoveries: that 'tis probable, longer Glasses 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 the 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. Rh