JOURNAL AND PROCEEDINGS. 85 
motion of a star is the angular motion which the star seems to make 
from the point of observation measured not in miles, but in seconds 
of arcs ; sometimes this motion is called “the right line motion or 
the star speed.” Astronomers have studied the speed of stars for 
years, and their work agrees well in making the average speed of 
stars about 21 miles per second. ‘The study of the proper motion 
of the stars has been prosecuted even longer and more generally 
than that of their speed, and the conclusion reached by this means 
that stars which have an apparent proper motion of 10 seconds of 
arc in 100 years must not be far from a distance of 180 light years, 
or describe the whole circle of the sky in 12,960 years. Now, then, 
if we apply the law of the cube of the number of stars related to 
distance, then we shall have reached the 30th sphere of light year 
distance and would have included in the list only about 27,000 
stars. We know that there are about 10,000 stars whose proper 
motion is as large as to seconds of arc which have been made the 
basis of calculation. Astronomers have made careful study of this 
part of our argument, and have said: ‘‘On the whole it seems likely 
that out of a distance of 300 or 4oo light years, or 18 trillions of 
miles, there is no marked inequality in star distribution.” If we go 
on and on and on, until we have reached a distance of 3000 light 
years, or 135 trillions of miles, possibly there would be a beginning 
of the thinning of the stars ahead of us; but let us make the journey 
10,000 light years, or 450 trillions of miles, then we might find our- 
selves nearly through that great ring of stars which we call the 
Milky Way, and the stars before us might probably have been 
thinned out so much that the great mass of them which we see from 
our terrestrial home would be left behind us. 
Suppose we set a celestial mark ro thousand light years from 
our sun and describe a great circle, the sun being the centre thereof, 
this circle would be 20 thousand light years across, or goo trillions 
of miles in diameter. 
I do not say, and astronomers do not assume, that such a 
circle would enclose the universe, but I do say that this is approxim- 
ately the size of the universe as conceived by the astronomer of 
to-day. But don’t misunderstand me. I do not say that this is the 
size or form of the universe, but this is the astronomers’ conception, 
