SCIENTIFIC SUMMARY. 
307 
auroral light gives the characteristic green line spectrum ; or, in other words, 
that spectroscopically dealt with, the slit being fine, the zodiacal light gives 
a background on which the faint auroral line (if aurora is present) may 
show itself as perfectly as though there were no zodiacal light at all. 
Hence Prof. Smyth’s observation not only demonstrate the real nature of 
the zodiacal spectrum, but shows how the mistake of those arose who have 
supposed the zodiacal spectrum to be identical with that of the aurora. 
Proper Motions of the Stars. — Dr. Huggins has been able to continue his 
researches into the proper motions of the stars in the direction of the line 
of sight. It will be remembered that the telescope he formerly used did 
not possess sufficient light-gathering power to deal with any star except Sirius. 
The instrument Dr. Huggins is now using has a light-gathering power four 
times as great. The first fruits of its employment in this line of research 
confirm in a very interesting manner the anticipations as well as the theories 
of Mr. Proctor. Dr. Huggins finds that certain stars are moving as if in 
systems or families, since they possess a common motion either of recess or 
approach. Among such instances may be mentioned one of a very remarkable 
kind. It may be remembered that Mr. Proctor, nearly three years ago, 
announced that the five stars (3, y, 7, ?, and £ Ursx Majoris, as well as Alcor 
close by £, and the telescopic companion of £, are moving in a common 
direction ; and at a lecture delivered in May, 1870, at the Royal Institution, 
Mr. Proctor expressed his conviction that whenever Dr. Huggins applied 
the spectroscopic method to these stars, he would find that they are either 
all receding or all approaching. Many, unaware of the evidence on which 
this conviction was based, considered so definite a prediction altogether 
unwise. It has, however, been amply confirmed by the event, since Dr. 
Huggins finds these five stars to be all receding at the rate of about thirty 
miles per second. On the other hand the star £, which Mr. Proctor had 
indicated as not belonging to the set, is found to have a spectrum differing 
in character from that common to the five stars, and though receding, has 
a different rate. The star a , also as marked by Mr. Proctor distinct from 
the rest, is found to have a totally different spectrum, and to be approaching. 
Thus the prediction referred to has been more than fulfilled ; it has been 
found not merely that all the stars of the set are receding at the same rate, 
but that other stars excluded from the set are not moving in the same way, 
and are furthermore distinguished by spectral differences from the members 
of the drifting-star family. 
Planets for the Quarter . — Saturn is the planet best placed for observation 
during the approaching quarter. He comes to apposition on July 9, at 
11 h. 13 m. Jupiter will be in conjunction with the Sun on August 3, 
4 h. 5 m. p.m., and is unfavourably situated for observation throughout the 
quarter. None of the other planets, (except Mercury) will be well placed 
during the quarter. Mercury will be at his greatest eastern elongation on 
August 3rd, and at his greatest westerly elongation September 15. 
August Meteors . — "We remind our readers to look out for the famous 
August meteors on the nights of August 9, 10, and 11. 
