Note 20 — MORE OBSERVATIONS MADE IN EGYPT, BY Guilandinus, Alpinus, and others.
Nicolaus Staphorst translation
The air of Egypt is confessed by the ancients to be often full of vapours; which appears both by the great dews that happened after the deluge of Nilus for several months; as also in that I have discovered at Alexandria, in the winter time, several obscure stars in the constellation of Ursa major, not visible in England; the which could not be discerned there, were there not a greater refraction at that time than with us, and consequently a greater condensation of the medium or air, as the optics demonstrate.