be reddest, the vapours are most dense.
On instruments for observing the moon (909. 910).
909.
If you want to prove why the moon appears larger than it is, when it reaches the horizon; take a lens which is highly convex on one surface and concave on the opposite, and place the concave side next the eye, and look at the object beyond the convex surface; by this means you will have produced an exact imitation of the atmosphere included beneath the sphere of fire and outside that of water; for this atmosphere is concave on the side next the earth, and convex towards the fire.
910.
Construct glasses to see the moon magnified.
[Footnote: See the Introduction, p. 136, Fracastoro says in his work Homocentres: "*Per dua specilla ocularla si quis perspiciat, alteri altero superposito, majora multo et