W. Harkness—The Solar Parallax. 391 
1792, Delambre, from more than a thousand eclipses of the 
first satellite (Astronomie par Jerome le Frangais 
(la Lande), 3"° edition. Paris, 1792, t. i, Tables 
astronomiques, p. 238. Also, Tables Keliptiques 
ag ney et es af Jupiter, ‘par M. Delam 
1874, Sugscat ce of the eclipses of fae pone 8 
atelli A dissertation for the degree of mas- 
ter of astronomy, by 8. Glasenapp. ablis hed in 
the Russian language, at St. Peeninee 1874, 
P 
= 
Lee) 
- 
Seen considered the probable error of his determination 
to be +1*02. 
Mein. —The following a are the principal determinations 
of the coefficient of aberration 
1728, Bradley (PTr, 1728, p. 5), adel. <tr ee ha 20°25 
1821, Brinkley (PTr, 1821, P- 350), a4 s5ssewies a sees 20°37 
1840. Henderson (MAS, 1840, xi, pind i Seat diws euliy eae 20°41 
1843. W. Struve (ANn, 3, bd. Xxi, 8. 66), 2. en e -e 20°445 
1844, C. A. F. Peters (ANn, 1844, bd. a Be LIB is fue ce 20°503 
1850. Maclear (MAS, 1851, vol. Xx, p. 9 én- 20 °6o 
1861. Main (MAS, 1861, my XXix, p. van’ yin ae a ei 20°335 
Solar Parallax.—The table below exhibits the various values 
of the solar parallax deducible from the foregoing values of V, 
@ and a by means of equations (29) and (80). I have rejected 
Fizeau and Foucault’s values of the velocity of light on the 
ground that they are merely first approximations, the details of 
which have never been published; and I have made no use of 
Helmert’s rediscussion of Cornu’s vitae The last column of 
the table gives the values of a and @ computed by means of 
equation (31) from the values of # and a in the first column, 
Velocity of 
Light_.__| 299,940 300,400 301,382 
Light equa’n Aberration 
493°-20 8”-894 8”°880 8”°B51 20”°26 
500°84 8°758 8°745 8°716 20°57 
Aberration Light equa’n 
20’-25 8897 8-883 87-854 493°*02 
"335 “860 "846 817 495°09 
37 "844 “831 “802 495°94 
“41 "827 814 "785 496°91 
"445 "B12 “799 “770 497°76 
“503 “787 “7173 Jao .¢ 499°19 
een ro 8-775 8-762 8°734 499°84 
