84 THE HAMILTON ASSOCIATION. 
stars even 93 millions of miles as a unit is by far too small and 
would make our mathematics stagger with the abundance of figures. 
Light, we know, travels 186,330 miles per second. In a year 
there are 31,558,000 seconds ; thus light would travel 45 millions of 
miles. Thus a light year is 45 millions of miles, or in other words, 
a light year is 63 thousand times the distance the earth from the sun. 
_* Now let us take a light year as our measuring rule and let us go out 
to measure the distance of the nearest fixed star, which is A Centauri, 
which is more than 4 light years distance or nearly 4% light years 
distance, which were we to use the mile unit would be 202 billions 
of miles. Leaving A Centauri we go out to 6 light years, and were 
we to describe a circle at that distance round the sun not likely more 
than A Centauri and the sun would be included in it, omitting our 
planets of course. Now let us double the radius and go out 12 light 
years, not likely in all this circle with a diameter of 24 light years 
would there be more than 8 stars. Add another 6 light years to this 
radius and describe another circle of 36 light years in diameter, and 
probably not more than 27 stars would be enclosed. But let us go 
another 6 light years and describe our circle this time 48 light years 
in diameter, and not more than 64 stars would be reached. Now, if 
we call a radius of 6 light years a unit, the first sphere having one 
star beside our sun, the second sphere with twice the radius contains 
8 stars, the cube of the two; the third circle, the cube of 3 or 27 
stars ; the fourth circle, the cube of 4 or 64 stars. Now, speed on 
in flight until we have reached the eighth sphere, or a distance of 48 
light years, and we will have reached our old familiar pole star. 
After we have thus done we then will have left behind us perhaps 
only 600 stars of the millions that we must consider in describing 
the size of the universe.” 
But with all this the astronomer has yet another step in consid- 
ering what is called the proper motion of stars. We speak of some 
stars as ‘‘fixed stars”; perhaps we should not do this, as the term is 
very misleading. We believe that probably every star in the sky is 
in motion, moving from one mile to one hundred miles per second, 
and some perhaps with greater velocity than this. 
There are two stars in the sky moving with such velocity that 
they move round the whole circle of the sky in the brief period of 
160 thousand and 180 thousand years respectively. The proper 
