236 The American Geologist. October, 1904. 
to find the weight of its mass, we must find its cubic contents 
and then multiply that by the weight of air, which is 815 
times less than that of water. 
We have already stated, that when the planet Xeptune was 
formed, the size of the nebula must have been limited by his 
orbit. Now, since the diameter of Xeptune's orbit is -5528 
million English miles, that must also have been the diameter 
of the nebula at that time. It is difficult to determine ac- 
curately the polar depressions, which arc said to have been 
considerable, as we have already noticed. We have hardly any 
reason to suppose, however, that the depression at both poles 
was greater than one third of the equatorial diameter. But if 
it were possible to suppose these depressions to be larger, let 
us, for safety's sake, square off the curvature on all sides of 
the nebula and assume its mass to be equal to that contained 
by a cube whose sides were only 3,500 million miles. This 
figure must then be multiplied by itself and the product of 
3,500 million in order to find the quantity we seek in cubic 
miles. 
The product which is to be multiplied by 3.500 million we 
find to be 12 quintillions and 250 quadrillions and this sum 
multiplied by 3,500 million gives 40 octillions, and 875 septill- 
ions, which represents the contents of the nebula in cubic 
miles. 
. In order to make this immense number a little more con- 
ceivable, let us remark, that one such cubic mile contains 254,- 
358,061,056,000 cul)ic inches, and that the Earth contains 260,- 
000,000,000 cubic miles, which makes 66 septillion cubic inches. 
The nebula would, consequently, contain 619 times as many 
cubic miles as the Earth contains cubic inches. 
Now, since air is 815 times lighter than water, and a cubic 
mile of water weighs 410 million tons, then a cubic mile of air 
must weigh 815 times less, or 503,067 tons. In order to find 
the weight of the nebular mass, we must then multiply its 
number of cubic miles by 503,067. 
This multiplication brings us to the highest power of nota- 
tion : 21 dccillion and nearly 569 nonillion tons. The com- 
bined weight of the Sun and the planets, according to modern 
astronomy, is 2 octillion and i8 septillion tons. Hence the 
