142 THE SUN’S MOTION IN SPACE. 
279 left available into two sets,—one of 135 stars brighter, the other of — 
144 stars fainter, than the eighth magnitude. The first collection gave 
for the goal of solar translation a point about 4° north of a Lyre, in R. 
A. 280°, Decl. + 43°; the second, one some thirty-seven minutes of 
time to the west of 5 Cygni, in R. A. 286°, Decl. + 45°. For a third 
and final solution, twenty-six stars moving 40/’-100” were rejected, and 
the remaining 253 classed in a single series. The upshot of their dis- 
cussion was to shift the apex of movement to R. A. 289°, Decl. + 51°. 
So far as the difference from the previous pair of results is capable of 
interpretation, it would seem to imply a predominant set towards the 
northeast of the twenty-six swifter motions subsequently dismissed as 
prejudicial, but in truth the data employed were not accurate enough 
to warrant so definite an inference. The Albany proper motions, as 
Prof. Boss was careful to explain, depend for the most part upon the 
right ascensions of Bessel’s and Lalande’s zones, and are hence subject 
to large errors. Their study must be regarded as suggestive rather 
than decisive. 
A better quality and a larger quantity of material was disposed of 
by the latest and perhaps the most laborious investigator of this intri- 
cate problem. M. Oscar Stumpe, of Bonn (Astr Nach., Nos. 2999, 3000), 
took his stars, to the number of 1,054, from various quarters, if chiefly 
from Auwers’s and Argelander’s lists, critically testing, however, the 
movement attributed to each of not less than 16” a century. This he 
fixed as the limit of secure determination, unless for stars observed with 
exceptional constancy and care. His discussion of them is instructive 
in more ways than one. Adopting Schoénfeld’s modification of Airy’s 
formule, (the additional computative burden imposed by it notwith- 
standing,) he introduced into his equations a fifth unknown quantity 
expressive of a possible stellar drift in galactic longitude. A negative 
result was obtained. No symptom came to light of “rotation” in the 
plane of the Milky Way. 
M. Stumpe’s intrepid industry was further shown in his disregard 
of customary “‘scamping” subterfuges. Expedients for abbreviation 
vainly spread their allurements; everyone of his 2,108 equations was 
separately and resolutely solved. A more important innovation was 
his substitution of proper motion for magnitude as a criterion of re- 
moteness. Dividing his stars on this principle into feur groups, he 
obtained an apex for the sun’s translation corresponding to each as 
follows: 
Apex 
be No. of ies 
aTOUp, included | Proper motion. Right | peti 
| ecli- 
stars. asceD- | J ation 
sion 5 
I 1 fo) oO 
7 DOS SOS SO IOC aS ae IIOG COM na Sea ee eee ee more 551 0.16 to 0,32 287.4 | + 42 
a Store mas cctaccnb tone Bases ate epee ne oe eh. 340 0.32 to 0.64 | 279.7 40.5 
TVi see ee 105 0.64 to 1.28 | 287.9 32.1 
fe lafolnl eta jeiafatwleihalwintehelaeielefare = sleaiviar=/oisie ecco s Semen meee 58 | 1.28 and upward | 285.2 30. 4 
