162 G. H. KNIBBS. 



mined upon the assumption that the 7 1 fundamental stars, whose 

 proper motions were discussed, belonged to the one dynamic system, 

 whose centre of inertia was supposed to be at rest. Bravais 

 recognised the great disadvantage of insufficient information as to 

 proper motions of stars in the southern hemisphere, and discussed 

 the effect of taking into account the distances of the stars and 

 their distribution in the celestial sphere. 



In the second note he found that, basing fresh calculations on 

 the proper motions of 62 stars of the first and second magnitudes 

 in the 1755 and 1830 catalogues, the sun's trajectory was directed 

 to a point nearly coincident with tj Herculis, and that its path 

 annually was 0*"28 at the mean distance of stars of the first 

 magnitude. The position of rj Herculis for 1843 would give 



R. A. = 249-°4, D. = + 39-°2 R. = CK28 

 as the coordinates of the direction of the sun's motion at that 

 date : R denotes mean distance of stars of first magnitude. 



(36) Bolzano, 18J/.3. 1 — Doppler had conceived and published the 

 idea that when a source of light, as a star, has a velocity as high 

 as thirty-three miles a second, to or from the observer, a sensible 

 consequent variation should exist, as he believed, in its colour. 2 

 Bolzano imagined that the changes of the light of the stars, taking 

 place through such movement, could be made to afford some 

 indication of its velocity, the distances between the stars and so 

 on. It will be necessary to refer to this matter later ; when the 

 nature of Doppler's misconception will be further adverted to. 



(37) Otto Struve and Peters, 1844? — Faye in 1859 quotes 

 Struve and Peters as having assigned the coordinates 



R.A. = 259-°75, D. = +34-°55 

 as specifying the direction of the path of our system in space for 

 the epoch 1859. 3 



1 Eine Paar Bemerkungen uber die neue Theorie in Herrn Doppler's 

 Schrift " Ueber das farbige Licht der Doppelsterne." — Pogg. Annal., 

 Bd. lx., 1843, pp. 83-88. 



2 Abhandl. der k. bohm. Gesell., Fol. v., Bd. n., 1841-2, pp. 465-482. 



3 Comptes rendus, 5 Dec. 1859, p. 873. 



