576 
Proceedings of the Royal Irish Academy, 
according to the period we assume. Schweizer's parallax of 0''*3743 
combined with Doberck's elements gives a mass of only 0*0366 that of 
the sun. 
Some recent measures are : — 
1882-76 
1882-87 
1886-974 
166°-28 
165 -70 
178 -64 
5"- 13, Doberck. 
5 "155, Engelmann. 
4 -71, Tarrant {A.JSf., 2866). 
4. 0. Struve 20 = 66 Piscium. This binary star has described an 
arc of about 70° of its apparent orbit since its discovery by 0. Struve 
in 1843, the distance diminishing from about 0''-66 to 0"-35. An 
orbit was computed by Prof. Glasenapp in 1889. The observations 
are fairly well represented, considering the difficulty of measuring so 
close a pair. Glasenapp says, " L'etoile 66 Piscium presente un objet 
tres difficile a observer ; il est k desirer que ceux qui possedent des 
instruments puissants I'observent annuellement." 
Some recent measures are : — 
1883- 84 
1884- 850 
1886- 80 
1887- 910 
1887- 93 
1888- 78 
2°-9 
357 -75 
349 -30 
352 -00 
351 -10 
350 -70 
0"'40, Perrotin. 
0 -525, „ 
(0 -45), H. Struve. 
0 -42, Tarrant 2899). 
(0 -40), H. Struve. 
-42), „ 
( 
5. B 36, Andromedse = 2 73. Txiis binary has described about 
60° of its apparent orbit since its discovery by Struve in 1830. The 
distance has slightly increased. Yariation in light was suspected by 
Schmidt. 
Some recent measures are : — 
l"-24, Doberck. 
1882-69 
: 359°-90 
1882-81 
2 
•65 
1882-81 
0 
•75 
1882-82 
3 
•80 
1882-93 
3 
•06 
1885-28 
2 
•0 
1888-05 
7 
•7 
•32, 
•40, 
•35, 
Perrotin. 
1 '18, Schiaparelli. 
A list of measures by Dr. Doberck from 1876 to 1882 will be 
found in the Transactions of the Eoyal Irish Academy, vol. xxix, 
part xm. (1890). 
