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which the arrow pointed shows the direction of the star’s ap- 
parent motion. This being done, it was possible to study the 
proper motions much more agreeably and satisfactorily than 
when they were simply presented in catalogues. And certain 
features, hitherto unrecognised, at once became apparent. 
Amongst these was the peculiarity which I have denominated 
66 Star drift the fact, namely, that certain groups of stars are 
travelling in a common direction.* This was indicated, in 
certain cases, in too significant a manner to be regarded as due 
merely to chance distribution in these stellar motions ; and I 
was able to select certain instances in which I asserted that the 
drift was unmistakable and real. 
Amongst these instances was one of a very remarkable kind. 
The “ seven stars ” of Ursa Major — the Septentriones of the 
Ancients — are known to all. For convenience of reference, let 
us suppose these seven divided as when the group is compared 
to a waggon and horses. Thus, there are four waggon- wheels 
and three horses. Now, if we take the waggon-wheels in se- 
quence round their quadrilateral (beginning with one of the 
pair farthest from the horses), so as to finish with the one which 
lies nearest to the horses — these are named by astronomers in 
that order Alpha, Beta, Gramma, and Delta of the Grreat Bear. 
Thus, Alpha and Beta are the well-known pointers (Alpha 
nearest the pole), and Delta is the faintest star of the Septen- 
trion set. The three horses are called in order Epsilon, Zeta, 
and Eta; Epsilon being nearest to Delta. Now when the proper 
motions of these seven stars had been mapped, I found that 
whereas Alpha and Eta are moving much as they would if the 
sun’s motion were alone in question, the other five are all moving 
at one and the same rate (on the star-sphere, that is) in almost 
the exactly opposite direction. Moreover, a small star close by 
Zeta (the middle horse), a star known to the Arabian astrono- 
mers as the “ Test,” because to see this star was held a proof of 
good eyesight, is moving in the same direction and at the same 
rate as Zeta and the rest of this set. And besides this star 
(which has also been called Jack by the Middle Horse), Zeta 
has a telescopic companion which also accompanies him in his 
motion on the celestial sphere. 
After a careful consideration of these circumstances, and an 
* I include this among “ features hitherto unrecognised, though Michell 
had already noted the fact that the stars are arranged into systems. “ We 
may conclude/’ he said, “that the stars are really collected together in 
clusters in some places, where they form a kind of systems; whilst in 
others there are few or none of them, to whatever cause this may he owing, 
whether to their mutual gravitation or to some other law or appointment of 
the Creator.” 
