CXV1 NOTES. 



pare Zach, Corr. Astron. Vol. vii. p. 105 ; Rigaud, Account of Harriot's 

 Astron. Papers, Oxford, 1833, p. 37 ; Biewster, Martyrs of Science, 1846, 

 p. 32. The earliest observations of Jupiter's satellites by Galileo and his 

 pupil Renieri, were only discovered two years ago. 



C 185 ) p. 317. It ought to be 73 years ; for the prohibition of the Coperni- 

 can system by the Congregation of the Index was given on the 5th of 

 March, 1616. 



C 86 ) p. 317. Freiherr von Breitschwert, Keppler's Leben, S. 36. 



(*) p. 317. Sir John Herschel, Astron. S. 465. 



f 488 ) p. 318. Galilei. Opere, T. ii. (Longitudine per via de' Pianeti 

 Medicei), p. 435506; NeUi, Vita, Vol. 2, p. 656688 ; Venturi, Memorie 

 e Lettere di G. Galilei, P. i. p. 177. As early as 1612, or scarcely two yean* 

 after the discovery of Jupiter's satellites, Galileo boasted, somewhat prema- 

 turely, of having completed tables of those satellites to such a degree of 

 exactness, that the phenomena could be computed by them to 1' of time. A 

 long diplomatic correspondence, which did not lead to the desired object, was 

 commenced with the Spanish ambassador in 1616, and with the Dutch ambas- 

 sador in 1636. The telescopes were to magnify 40 to 50 times. In order 

 to find the satellites more easily when the ship is in motion, and (as he 

 imagined) to keep them in the field, he invented, in 1617 (Nelli, Vol. ii. 

 p. 663), the binocular telescope, which has usually been attributed to the 

 Capucine monk, Schyrleus de Rheita, who had much experience in optical 

 matters, and was seeking to find the means of constructing telescopes magni- 

 fying 4000 'times. Galileo made experiments with his binocular (to which he 

 also gave the name of celatone or testiera) in the harbour of Leghorn, during 

 a strong wind and much motion of the ship. He also had a contrivance pre- 

 pared in the arsenal at Pisa, for protecting the observer of the satellites from, 

 the motion of the ship, by seating him in a kind of boat, which was to float 

 in another boat filled with water or with oil (Lettera al Picchena de 22 Marzo, 

 1617 ; Nelli, Vita, Vol. i. p. 184 ; Galilei, Opere, T. ii. p. 473 ; Lettera a 

 Lorenzo Realio del 5 Giugno, 1637). The proofs which Galileo assigns of the 

 advantages for the naval service of his method over Morin's method of lunar 

 distances, are very remarkable. (Opere, T. ii. p. 454) 



O p. 319. Arago, in the Annuaire for 1842, pp. 460476 (Decouvertes 

 des taches Solaires et de la Rotation du Soleil), and Brewster (Martyrs of 

 Science, pp. 36 and 39) place the first observation of Galileo in October or 

 November 1610. Compare Nelli, Vita, Vol. i. pp. 324384 ; Galilei, Opere, 

 -T' i. p. lix. T. ii. pp. 85200, T. iv. p. 53. On Harriot's observations, see 



