102 
stars, as they are called, are never per- 
mitted to shine together?—to kindle 
each other’s emulation, and correct 
each other’s mannerisms, by the colli- 
sion of a generous rivalry. A 
ee 
To the Editor of the Monthly Magazine. 
Sir: 
LLOW wme to make a few remarks 
on your correspondent A. B.C.’s 
critical observations on Capt. Scoresby’s . 
Voyage sto the Arctic Regions [see 
Monthly Magazine, Vol. LIX. p. 21]; 
a work I have not had an opportunity 
of perusing: and, therefore, I shall only 
say, that it appears probable, that while 
the principal aim of Capt. Scoresby was 
to entertain, he was anxious not to mis- 
lead his readers; as, indeed, the quo- 
tation evinces. 
But whatever may be thought of 
Capt. S.’s philosophy (and I am quite 
ready to join A. B.C. in disputing it, as 
far as appears in the quotations in ques- 
tion), surely it will be granted, that A. 
B.C. has not been very successful in the 
illustration of his position. A.B.C. has 
commenced by observing, “ The calcu- 
lations I shall not follow, because I 
deny the principles altogether: —I 
would address A.B.C. in language nearly 
similar. 
It would, however, be very unjust, 
were I not to acknowledge, that A.B.C. 
has. done much to disarm criticism, in 
his. concluding paragraph ;—and, if he 
thinks the term “nonsense” may be 
applicable to his “remarks,” J, for my 
part, will not gainsay it. 
But the subject is curious ; and it isa 
fact, notwithstanding A. B.C.’s apparent 
doubt, tliat every middle-sized man sus- 
tains.a pressure of several thousand 
pounds: for as every square inch of 
surface sustains a pressure of 15 lbs., 
every square foot will sustain 144 times 
as much, or 2,160 lbs. weight ;—then, if 
the whole surface of a man’s body con- 
tain fifteen square feet, he must sustain 
32,400 lbs., nearly fourteen tons and a 
half; or, supposing a small man, con- 
taining thirteen or fourteen superficial 
feet, he will then, even, sustain upwards 
of thirteen tons weight. 
The difficulty then occurs, “ How 
comes it that we are insensible to a 
pressure seemingly sufficient to crush us 
at once ?”—~an objection which obtains 
the more powerfully, from the general 
admission (though A.B.C. “ justly” 
disallows it), that “when a man is 
plunged, only a few feet, under water, 
Atmospheric and Aqueous Pressure. 
[Mar. 1, 
he is sensible of the pressure;” and a 
glass, open at both ends, being placed 
over the hole in an air-pump plate, and 
while the hand is pressed over the other 
end, the air being exhausted, this 
pressure will not only be perceived, but 
painfully felt. 
The reason is :—such pressures, only, 
are acknowledged by us, as move our 
fibres, and put them into unusual situa- 
tions; and the pressure of the air, being 
equal on all parts, cannot displace, but, 
on the contrary, braces the fibres. If, 
however, the pressure be removed from 
any part, that on the neighbouring parts 
becomes even painful; and if the top of 
the glass, above described, be covered by 
a piece of flat glass, such flat glass, upon 
exhaustion of the receiver, would: be 
broken to atoms by the incumbent 
weight of air; which would, also, be the 
case with the other glass, or receiver, 
too, but for the arched top. 
“ As light as air,’ is a common say- 
ing; but that air has weight, was well 
known to Aristotle. Did A.B.C. never 
hear of the experiments of Galileo and 
Torricelli, on this subject? But, take 
an hollow copper ball, holding exactly 
a wine-quart, and having weighed it, 
carefully, when full of air, exhaust it, 
and then weigh it: it will be found, on 
comparison with the former weight, to 
have lost sixteen grains ; and this result, 
compared. with the weight of the same 
vessel filled with water, shews water to 
be 914 times as heavy as air, near the 
earth’s surface. This, by the bye, pro- 
bably explains, in part, A.B.C.’s obser- 
vation, that “it is only guessed at, but 
not known, what the weight of the at- 
mosphere is:” for the temperature and 
density of the air vary at, and, much 
more, high above the earth’s surface; 
which, in round numbers, contains 
200,000,000 square miles, every square 
mile containing 27,876,400 square feet + 
therefore, the earth’s surface contains 
5,575,280,000,000,000 square feet;— 
which number, multiplied by the pres- 
sure on a square foot (2,160), gives 
12,042,604,800,000,000,000, for the 
whole weight of our atmosphere. 
Of this, however, and its conse- 
quences, I believe that A.B.C. is aware ; 
and his after-quotation of Dr. Blair’s 
celebrated, and really just axiom, shews 
that the attentive perusal of some good 
works on pneumatics and hydrostatics 
is rather desirable to A.B.C., than the 
explication of any particular fact. 
Thus we see, that when it is said, the 
whale “has not the weight of a single 
ounce” 
