TO KNOW THE STARRY H EAVENS 
In Figure 3 we have a diagram of 
the system. It shows the dark body 
moving about the bright one. The 
earth lies in the direction of the arrow. 
We would receive the full light from 
both bodies except when the dark body 
lies in front or back of the bright one. 
\\ hen the dark one is in front, as at A, 
we have a partial eclipse which causes 
the big decrease in brightness. When 
the dark body is behind, a part of its 
light is cut off, but the loss of light is 
slight. The eclipse is not total as the 
dark body does not come exactly be- 
tween the bright star and the earth. 
\\ e are thus able to tell much about a 
body which we have never seen. Both 
bodies have very slight density com- 
pared with that of the sun. 
High Points Above Our Earth’s 
Surface. 
BY CHARLES NEVERS HOLMES, NEWTON, 
MASS. 
We all know that we are surrounded 
by an atmosphere and that this atmos- 
phere extends upwards for many miles. 
Some of us know that it has been esti- 
mated that, were all this atmosphere 
109 
1 he answer is, at least three hundred 
miles, and these three hundred miles 
are divided into several strata. The 
stratum closest to the terrestrial sur- 
face, which surrounds 11s, is called the 
“Troposphere,” seven miles in height, 
and above the “Troposphere,” there 
follow respectively the “Stratosphere” 
(about forty miles high), the “Hydro- 
gen-sphere” (about eighty miles high), 
and, finally, the so-called “Geocoron- 
iutn-sphere” (which extends from the 
“Hydrogen-sphere” to the top of the 
atmosphere). With the “Hydrogen” 
and the “Geocoronium” spheres we are 
not concerned, since the “high points” 
in this short article lie wholly within 
the “ 1 ropo” or the “Strato” sphere. 
1 he top of the “Stratosphere” is about 
forty-seven miles above sea level, and 
clouds and storms are found forty 
miles below, in the “Troposphere.” As 
is very evident, the “Troposphere” is 
the home sphere of the human race. 
Most of us live near the bottom of 
this “Troposphere,” and even the lofty 
summit of mighty Mount Everest does 
not reach as high as the top of the 
“ 1 roposphere.” However, it is believed 
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equally dense, it would not extend more 
than five miles above our earth’s sur- 
face, not quite as high as Mount Ever- 
est, the highest mountain on our globe. 
But our atmosphere becomes rarer and 
rarer as we ascend, the density of air 
being at an altitude of 36/10 miles 
one-half that which it is at sea level. 
The question is, how high above the 
terrestrial surface does our atmosphere 
extend ? 
that a balloon or balloons, containing 
human beings, have ascended as high 
as the bottom of the “Stratosphere” 
and, it may be, one of these balloons 
has even invaded the “Stratosphere.” 
It is certain that “sounding balloons,” 
that is, not containing human beings, 
have penetrated this “Stratosphere” for 
quite a distance, one of these “un- 
manned” balloons attaining a height of 
about twenty miles. It will be exceed- 
