[7]This was ascertained from several observations of the depression of the visible horizon, corrections for spheroidal figure of the earth, and northern deviation being made, and ¹⁄₁₁ allowed for terrestrial refraction.

[8]The height of this range is ascertained trigonometrically.

[9]See Wilkins’s Vitruvius.

[10]The following remarks on the ports and vessels of the ancients are drawn from the Archæologia of Potter; and we have thought it not irrelevant to the subject to bring them together on the present occasion.

[11]Diodorus, lib. xii.

[12]The harbour at Ptolemeta presents an example of works of this description.

[13]

——— Gemuit sub pondere cymba

Suctilis, et multam accepit rimosa paludem.—Æneid, vi. 414.

[14]