8 Aqueous and Atmospheric Pressure. 
‘ mouth), acquire their ultimate contra- 
; distinctness from the. precise positions 
of. thes ates. In -the «guttural, if not 
nearly; passive to the action of the 
“pvuLAand velum palati,. it has, at least 
(where. those organs are perfectly form- 
_ed) only a common share in the action. 
Its liquid, semi-liquid, and consonant 
impulses are produced by contact with 
‘The Passive Organs—the Gums and 
‘the Teeth. 
( To be continued. ) 
‘To the Editor of the Monthly Magazine. 
Sir: 
._A& LLOW me to submit to the con- 
sideration of your readers some 
brief observations, relative to your criti- 
cal remarks on certain passages ‘con- 
tained in a letter signed “ James Leigh, 
Chelsea.” ¢ 
"When, I ask, have “ men that have 
ascended the highest mountains expe- 
tienced the gratification of having a 
part of the load they endured in the 
valley, removed ?”—it is replied :— 
* Certainly they have: it is a notorious 
fact, that the atmosphere is there less 
dense, the respiration more free, and 
animal circulation more accelerated,” 
&c.—Now, I am well aware that. these 
exhilarating sensations have been expe- 
rienced by persons that have. ascended 
mountains, both great and small; but 
am not conscious that they have been 
attributable to a perceptible diminution 
perpendicular pressure. Unless the 
een made demonstrates that these 
effects are equivalent, or similar in their 
operation, to a diminution of superin- 
cumbent weight, it is no objection to 
my question whatever. 
. It is next observed, that “this, how- 
ever, makes nothing to the question at 
issue. The water is not, in this respect, 
like the air. At least, it has not yet 
been shewn. that it is more dense fifty 
fathoms deep than near the surface; or, 
if it be (for that may be a disputed 
pomt), the exhaustion or sense of op- 
pression may be attributable to that 
density, and not necessarily to super- 
imcumbent weight or perpendicular 
pressure.”—I am quite at a loss to 
imagine how the increased density of 
the fluid (assuming this as a fact, which, 
by the way, is surely quite incontro- 
vertible) in which the whale at the 
bottom of the ocean is immersed, can 
possibly be considered as the cause of 
oppression or distress, unless the water 
were respited by the whale,* which it 
.* Does our correspondent mean ‘to be 
[Alug. 1, 
is not, at least, by fish of the cetaceous 
genus, the, circulation! of’ thei» blood 
being very similar,,to that. of. other 
mammalia, and, eaiseriacdthy, hi are 
soon suffocated,’ When attempt = 
respire under the water. ' ‘he eae. 
ment from the harpoon quickly produces: 
an expenditure of that’ prtibi Obllait, 
which the whale carries’ down with it. 
On my allusion to the ¢ylindrical. 
vacuum in support of my argument,’ it 
is objected, “ But the) glass top of the 
cylinder is here supposed to be a/flat 
surface—it is, therefore, not equally 
surrounded, but has to sustain a super- 
incumbent pressure only. The experi- 
ment of the vacuum, therefore, to refiite 
or support the argument of out corre-: 
spondent, should be made with a sphére 
or hemisphere, and the glass: should be: 
every where of equal thickness.”—Yet, 
if 1 have been unlucky in the choice of 
my simile, surely it must be acknow- 
ledged that you have been equally so z 
for if a whale be not of a cylindrical, ib 
is certainly not of a spherical form, and: 
it is only necessary to refer to @ simile. 
The fact is, that a parallelogramical 
vacuum. ought to have been alluded to, 
and then it could not have-been dénied; 
that the one is “as equally surrounded 
by the same element” as the other— 
both having a superincumbent and (if 
I may be allowed the liberty of coining 
a word particularly appropriate, for the 
occasion) a subterincumbent pressure to 
resist, that is, supposing for a fair trial 
that the vitreous parallelogram be ‘sus- 
pended above the earth’s surface. ~~ 
When I maintain that “ the whale, at 
the surface of the water, is ‘as much 
pressed. (i.e. distressingly) as the Whale 
at the bottom,” I do so on this ground, 
that if fluids press in every direction, 
then whatever comes into contact with 
them must evidently be pressed, ‘al- 
though not in an equal degree) for, at 
the bottom, the natural pressure is act- 
ing in conjunction with, and, at the top, 
the natural pressure is acting in oppo- 
sition to, the specific gravity of thé fluid. 
But whether the incumbent weight be 
great or small, it is alike unproduétive 
of any exhaustion to the first, so“ long 
as the vis ponderis. is not spent in its 
body, but is transmitted through it to 
the ground. James LEYGH. — 
May 10, 1825. _ on eee 
understood, that there is no mare vesistanee 
in a dense than in a rarefied medium?=-that. 
motion or exhaustion would be just.as easy 
3 te eT Re Ss 
in the one as in ay Other? Se gica vee 
