Crossword-Solution: RARIFY 6 letters, 1 clue 🏆 scrabble score: 12

And if the eggs of the larger description of swans, or leather balls stitched with fine thongs, be filled with nitre, the purest sulphur quicksilver, or kindred materials which rarify by their caloric energy, and if they externally resemble pigeons, they will easily be mistaken for flying animals." Thus it would seem that, hunting back in history, there were three main ideas on which would-be aeronauts of old exercised their ingenuity.

This we find experimentally verify’d in the Air, which though a _medium_ a thousand times more rarify’d then the water, the resistance of it to motions made through it, is yet so sensible to very minute bodies, that a Down-feather (the least of whose parts seem yet bigger then these Eels, and many of them almost incomparably bigger, such as the quill and stalk) is suspended by it, and carried to and fro as if it had no weight.

And further, if there chance to blow any wind, or that the air between you and the Object be in a motion or current, whereby the parts of it, both rarify’d and condens’d, are swiftly remov’d towards the right or left, if then you observe the Horizontal ridge of a Hill far distant, through a very good _Telescope_, you shall find it to wave much like the Sea, and those waves will appear to pass the same way with the wind.

That there is an Air abroad sufficient to divide and resolve them, or the Heat of the Sun has been strong enough to exhale them, that is, to rarify them, so as to render them lighter than the Air through which they were to pass.

For, though one would think, that it were {235} advantagious to rarify and drive out the Air as much as is possible, because in such seal'd Bubles the Air it self (as I have elsewhere shewn) has a weight; yet this advantage countervails not the inconvenience of being obliged to increase the weight of the Glass, which when it includes highly rarified Air, if it be not somewhat strong, will be broken by the pressure of the External Air, as I have sufficiently tryed.