TO KNOW THE STARRY HEAVENS 
23 
What is the Weight of Our Atmos- 
phere? 
BY CHARLES N EVERS HOLMES, NEWTON, 
MASSACHUSETTS. 
We all know that the atmosphere 
consists of nitrogen and oxygen, mixed 
with several other gases. Of these 
gases, oxygen is somewhat heavier than 
nitrogen but, as we are well aware, air 
is very light ; indeed, water is 773 times 
heavier than air. Nevertheless, air has 
weight, and the total atmosphere has 
an enormous weight. The reason why 
we are not instantly overwhelmed by 
atmospheric pressure is that its inward 
pressure is counteracted and balanced 
by its outward pressure. However, if 
we climb a mountain we are sometimes 
troubled when the air pressure outside 
of our eardrum becomes less than the 
air pressure inside of our eardrum. 
The atmosphere has been estimated 
to extend about 300 miles above our 
earth’s surface. It covers a total terres- 
trial area of 197,000.000 square miles. 
Such being the case, it seems a little 
less remarkable that each square inch 
of our body is receiving a counteracted 
and balanced pressure of almost 15 
pounds. That is to say, since the body 
of an average man possesses about 1,900 
square inches, his body is sustaining a 
total neutralized pressure approximat- 
ing 14 tons! Or, in other words, a sur- 
face as large as a square 20 feet by 20 
feet — 400 square feet — would receive a 
counteracted atmospheric weight of 
about 423 tons. If only one-half of this 
423 tons’ energy could be applied to a 
movable surface 20 feet by 20 feet — if 
only one-fourth of this atmospheric 
pressure could be utilized — what a 
revolution in aeronautic science would 
result ! 
It has been estimated that the total 
volume of our atmosphere weighs ap- 
proximate!}' 1/1,200,000 the weight of 
the terrestrial globe. Now, since the 
weight of the terrestrial globe has been 
satisfactorily approximated at 6,000,- 
000,000.000.000,000,000 tons, it follows, 
from that estimate of 1/1,200,000, that 
the total volume of our atmosphere 
weighs about 5,000,000,000,000,000 tons. 
Let us verify this estimate. The 
barometer has proved that at sea level 
our atmosphere exerts a pressure of 
about 147/10 pounds per square inch. 
It is certain that all of the atmospheric 
weight must press upon the 197,000.000 
square miles of terrestrial surface; that 
is, upon about 790 quadrillion square 
inches. Therefore, if we multiply the 
earth’s surface of about 790 quadrillion 
square inches by 144/10 pounds (the 
average atmospheric pressure), we ob- 
tain the approximate weight of our 
atmosphere — 5,695,000,000,000,000 tons. 
This weight of 5,695 trillion tons is 
greater than the older estimated weight 
of 5,000 trillion tons, and is probably 
nearer correct. That is, the total weight 
of our atmosphere approximates 5 7/10 
quadrillion tons. 
We may verify these figures another 
way. It has been calculated that if the 
whole of our atmosphere were concen- 
trated to sea level density, it would rise 
about 26,000 feet instead of 300 miles. 
Such a concentrated atmosphere would 
contain approximately 141 quintillion 
cubic feet. Now a cubic foot of air 
weighs about 1 293/1000 ozs. Accord- 
ingly by multiplying 14T quintillion 
cubic feet by 1 293/1000 ounces, we ob- 
tain 182 313/1000 quintillion ounces, 
which, divided respectively by 16 
ounces and 2,000 pounds, approximate 
5,695,000,000,000,000 tons, which verify 
the preceding calculation very closely. 
It must be admitted, therefore, that our 
earth’s atmosphere has a tremendous 
weight, although its weight approxi- 
mates only 1/276 that of the terrestrial 
waters. 
The Evergreen Wood. 
In the evergreen wood it is always June, 
Perennial freshness reigns, 
And not a footfall can be heard 
As we saunter through its lanes. 
For carpet moss, both thick and soft, 
Is spread from tree to tree. 
Its emerald freshness a delight, 
As far as eye can see. 
The spruces and the fragrant fir, 
That fill such haunts as these. 
Are overtopped by lofty pine, 
The king of forest trees. 
And at their bases nestle ferns, 
As in the Summertime, 
For Winter ferns, like conifers, 
Are ever in their prime. 
Bright poly-podys cushion rocks, 
Inviting us to rest, 
Which we are never loath to do, 
At their unique behest. 
Yes, Summer dwells in the spicy wood, 
E’en to the end of the year; 
Until it dons its ermine white, 
And gives us Winter cheer. 
— Emma Peirce. 
