ge A SOUTHERN OBSERVATORY. 
out to be physically connected, consequently, at nearly the same dis- 
tance from ourselves with the giant luminary they attend. This doubt 
will shortly be set at rest by Dr. Gill’s measures, now being carried out 
with a different pair of stars. 
Sirius was shown by the observations of 1881-83 to be at a distance 
such that its light occupies nearly nine years in reaching us. Its real 
brightness is that of sixty-three suns, while it attracts the semi-obscure 
body circulating round it in forty-nine years, with no more than thrice 
the solar power. This extraordinary luster relative to mass seems to 
belong to all stars of the Sirian pattern as to spectrum, and is due most 
likely in part to their elevated temperatures, in part to the scantiness 
of their vaporous surroundings. 
The success of the Cape investigations in this difficult branch of as- 
tronomy invited their continuation on a larger scale, and with more 
powerful instrumental means. The Government was accordingly in- 
duced to sanction the construction, by Messrs. Repsold of Hamburg, 
of a new heliometer of above 7 inches aperture, mounted last year in a 
building erected,for its reception on the summit of the sunny slopes of 
Observatory Hill. The first view of this great star-measuring machine 
has, it must be admitted, a somewhat bewildering effect upon the un- 
initiated onlooker. The eye end literally bristles with steel rods, han- 
dles, and screw-heads, almost as numerous as the stops of an organ, 
and requiring no less skill and knowledge for their proper use. The 
revolving ‘ head” is armed with a strange-looking, radiated head-gear, 
like the sails of a windmill, or a nimbus of tin sectors surviving from a 
barbarous age. 
Everything here has however a definite purpose. These surprising 
“flappers” are, in fact, screens of wire gauze of graduated closeness, 
used for equalizing the brightness of the stars in the field of view, and 
so enabling the eye to hold the balance, as it were,even between them. 
The complex apparatus close to the observer’s hand furnishes him with 
the means of easy control over the whole of the sky-gauging mechanism 
provided for him. None more perfect has been devised, yet the study 
of its “errors” is the indispensable preliminary to its use. 
Only the sublime end in view could render tolerable the process of 
arriving at a complete “theory” of such an instrument. The patient 
laboriousness so readily commended in the heroes of science costs more 
than the readers of their biographies are apt toimagine. Interminable 
readings of scale divisions, interminable castings-up of the columns of 
decimals expressing the differences of the successive readings, are not 
in themselves exciting occupations. But they must be pursued during 
some hours a day for a whole year before the “division errors” of the 
new heliometer can be regarded as completely abolished because per- 
fectly known. Nor is this all. Elaborate corrections and interpreta- 
tions of other kinds have to be added, to say nothing of endless and 
anxious “precautions in the observations themselves—precautions 
against personal and physiological, as well as against atmospheric and 
