[156] Ibid: 409-410.

[157] The Tychonic system has supporters to this day. See [chap. v].

[158] Dreyer: 181.

[159] The authoritative biography is the Vita by Frisch in vol. VIII, pp. 668-1028 of Op. Om. Kep.

[160] Frisch: VIII, 718.

[161] Delambre: Astr. Mod. 314-315.

[162] Frisch: VIII, 999.

[163] Ibid: VIII, 696.

[164] Ibid: VIII, 699-715.

[165] Dreyer: 290-309.