Nile's Inundations, the cause attributed to Niter, by Dela Chambre; opposed by Vossius. See both in the List of Books, 14. [251]. and 17. [304].

The North-Countries of Poland, Sweden, Denmark, &c. are warm'd by the influence of the Royal Society, 19. [344].

O.

Ocean, what Seas may be joined with it, 3. [41].

Opticks, Campani's Glasses do excell Divini's; 'tis easie by them to distinguish people at four Leagues distance, 2. [131]. and 12. [209].

What they discover in Jupiter and Saturn, 1. [1]. and [2].

The proportions of Apertures in Perspectives reduced to a Table by M. Auzout, 4. [55].

Animadverted upon by M. Hook, 4. [69].

How to illuminate Objects to whatsoever proportion, proposed by M. Auzout, 4. [75].

Hevelius, Hugenius, and some in England, endeavour to improve Optick Glasses, 6. [98].