NEWS FROM THE STARS. 
389 
Now, Secchi announced that the stars of the Great Bear, with 
the exception of Alpha, have spectra belonging to the same type 
as the spectrum of the bright stars Sirius, Vega, Altair, Re- 
gulus, and Rigel. This result was in very pleasing accordance 
with the anticipations I had formed, except that I should rather 
have expected to find that the star Eta had a spectrum unlike 
that of the remaining five stars of the Septentriones. More- 
over, as the stars belonging to this particular type are cer- 
tainly in many cases, and probably in all, very large orbs* 
(referring here to real magnitude, not to apparent brilliancy), 
the inference seemed fairly deducible that the drifting five stars 
are not nearer than Alpha, and therefore (since we have seen 
that it is unlikely that all the Septentriones lie at nearly the 
same distance) the inference would be that the drifting stars 
lie much farther away than the rest. 
It remained, however, that the crucial test of motion-measure- 
ment should be applied. 
In the middle of May last I received a letter from Dr. Hug- 
gins announcing that the five are all receding from the earth. 
In all the hydrogen line called F, is “ strong and broad.” In the 
spectrum of Alpha the line F is “ not very strong ” (so faint, 
indeed, Dr. Huggins afterwards informed me, that he preferred 
to determine the star’s motion by one of the lines due to mag- 
nesium in the star’s atmosphere. He found that Alpha is ap- 
proaching. As to Eta, Dr. Huggins remarked that the line at 
F is “ not so strong or so broad ” as in the spectrum of “ the 
five.” He was uncertain as to the direction of motion, and 
mentioned that <c the star was to be observed again.” He subse- 
quently found that this star is receding. But whereas all the 
five are receding at the enormous rate of 30 miles per second, 
Eta’s recession was so much smaller that, as we have seen, Dr. 
Huggins was unable to satisfy himself at a single observation 
that the star was receding at all. 
It will be seen that my anticipations were more than fulfilled. 
The community of recessional motion was accompanied by evi- 
dence which might very well have been wanting — viz., by the 
discovery that neither Eta nor Alpha shared in the motion. 
Moreover, the physical association between the five stars was 
yet further evidenced by the close resemblance found to exist 
between the spectra of the five stars. Dr. Huggins remarked 
in his letter, “ My expectation had nothing to do with the above 
results. At the moment, I thought Alpha was included in the 
* Sirius 4 demonstrably gives out much more light than our sun, and 
according to the best determinations of his distance he must (if his surface 
is of equal intrinsic lustre) be from 2,000 to 8,000 times larger than the sun. 
Vega, Altair, and Rigel are also certainly larger and may be very much 
larger than our sun. 
