[97] Aristarchi Samii de Mundi Systemate. Parisiis 1644.

[98] See page [12].

[99] De Cœlo, lib. iv. cap. 3.

[100] Reflexiones Physico-Mathematicæ, Parisiis, 1647.

[101] Venturi.

[102] Riccioli.

[103] The notions commonly entertained of 'up' and 'down,' as connected with the observer's own situation, had long been a stumbling-block in the way of the new doctrines. When Columbus held out the certainty of arriving in India by sailing to the westward on account of the earth's roundness, it was gravely objected, that it might be well enough to sail down to India, but that the chief difficulty would consist in climbing up back again.

[104] See page [50].

[105] Riccioli Almag. Nov.

[106] Plutarch, De placit. Philos. lib. iii. c. 17.