X X. 
The Sun a small Star. 
Bx ALVAN CLARK. 
(Communicated January 28, 1863.) 
Or all the efforts to determine the parallax of stars, both by direct and differential 
methods, only ten or twelve cases can be cited with any show whatever of success. In 
a Centauri it amounts to 1”, which is more than double the quantity imputed to 
either of the others. The conclusion follows, among astronomers, that the stars gen- 
erally are immensely distant bodies, shining like the Sun with light of their own, and 
forming a great family of which he is an individual member. 
The sum total of light given off by any luminous body can be computed where its 
distance is known; and it is supposed, from such computation, that several of these 
stars must considerably exceed the Sun in intrinsic lustre, while 61 Cygni falls below . 
him. Therefore, though classed in one family, inequalities are admitted, and to what 
extent they may reach among the millions, visible and invisible, we cannot know; 
but, from all the analogies of nature, we may safely conjecture that the extremes are 
very great. 
If we admit this, and suppose for all the stars in existence a mean equal to our Sun, 
or even less, those visible must possess a mean in brightness much in excess of his; 
for, by the laws of perspective, the smaller would be lost to our view, at distances from 
which the brighter might glow, even as first magnitude. This reasoning would apply 
to telescopic magnitudes as well as to those visible with the naked eye. 
Believing this to be true, I have felt a desire to possess some method of making 
photometrical comparisons between the light received from the Sun and that from a 
star more reliable than these in common use. If you were to go within the tropics, 
and sink a well to the depth of several hundred feet, and place yourself at the bottom 
while an assistant should close the top to produce total obscuration, except one small 
VOL. VIII. riri 
