884 W. Harkness—The Solar Parallax. 
the most trustworthy result is that by Mr. Wm. Ferrel of the 
United States Coast Survey, who found the moon’s mass 
from the tides at Brest ae and from the tides at Boston 
1 : 
EY the most probable mean being _ . (Jour. Frank. Inst., 
1871, vol. 1xi, p. 366.) 
In 1755, D’Alembert determined the moon’s mass from the 
attemptis by Mr. H. J. Stone (MNt, 1868, vol. xxviii, p. 43), who 
considers that his equations are accurate to terms of the third 
order in the lunar theory. With some changes of notation, 
they are 
Ma ) 
e= 
Sa,* | 
mek (15) 
W — Anu+Bue | 
< : O = Cue J 
in which 
Be, } 
B=1+ ~—6y" r (16) 
_ 97 (83 _ 5° 
a (49 2 ) Jen | 
Elimiting x and ¢ from the equations (15), and introducing 
the sines of the parallaxes instead of the mean distances, we 
get 
ca sin’ p.AOS (17) 
= sin’ P (CW — BO) 
which becomes 
_ [2411505] AQ as) 
~ sin’ P (CY — BO) 
by substituting the value of S sin’p from (9). The number 
within the square brackets is the logarithm of the quantity 
which it represents. Ten must be subtracted from its charac- 
teristic. 
We will take 
y = 0°04488663 
é = 0°0548993 
e, = 0°0167711 
p= —19° 21’ 20” = —0°337818 of radius. 
P= 34g 7 
