Plate 4. fig. 2.

See Newton's Optics, book iii.

The observations here alluded to never appeared.

See par. 478.

As these terms are afterwards referred to (par. 525), it was necessary to preserve them.

Steigerung, literally gradual ascent. See the note to par. 523.

Curcuma, Bixa Orellana, Carthamus Tinctorius.