eer) bic 
Astronomy. 77 
length of 512 mm.; but great uncertainty attaches to this deter- 
mination as a slight derangement of the spectroscope prevented 
the introduction of a comparison spectrum. On September 3, 
very reliable result was ‘6 mm. single measure of min 
gave 4961. It will be at once seen that the light of this remnants 
nd 
found 500°8 mm, and 493°5 as limiting wave-lengths between which 
the whole width of the line must be enclosed. Bearing in min 
the history of this star from the time of its discovery by Schmidt 
it would seem certain that we have an instance before us in 
which a star has changed into a owenets —— of small angu- 
lar diameter. At least it may ely affirmed that no astrono- 
mer discovering the object in its iochnat atene would, after view- 
ing it through a prism, hesitate to pronounce as to its present neb- 
ulous character. Judging from the brightness of the star in the 
finders of 33 inch aperture it is probable that a refractor of 5 
inches aperture a sufficient to show the monochromatic 
aoe of its light when viewed through a small direct-vision 
e "The Report of Professor Pickering, Director of the Harvard 
College Observatory, to the Visitors, Nov. 26, 1877, has been pub- 
lished. It has been decided to devote the large refractor to 
photometric work and some results of general interest have been 
r d g 
¥ 
giving the cians to which the primary must be reduced to 
render it no brighter than the satellite, or the diameter of the lat- 
ter, if it reflected light in the same proportion as the planet. This 
is, in fact, probably the only estimate we can ever make of the 
true diameter of these bodies, An approximate reduction of the 
. . co 
from the holes, gives its equivalent diameter at about 5-9 =e 
: his 
ay 
inner satellite give its diameter as 65 miles. The direct compari- 
son of the two gives their relative diameters as in the ratio of 
10 to 9. These figures will be somewhat altered in the final re- 
duction. As the darker color of the outer satellite somewhat 
diminishes its light, it is probably safe to call it about six miles 
in diameter, and the inner satellite seven miles 
This photometer has since been used upon various other objects. 
A large number of measurements of seven of the rage ee of 
object 
Saturn have been obtained, including the very faint 
