iffering 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
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 _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 multitude