East Guilford, March. 6. Anno Domi 1753
I number it among the fortunate Occurrences of
my Life that I have been indulged an Interest in your Friendship. I
wish I could better deserve it. Amongst many other agreable
Pleasures this Way deriv’d, I esteem it a considerable One, to
enjoy the Benefit of Seeing now and then Some entertaining Pieces
communicated to your Self by Some of your ingenious Correspondents,
Amongst all of which I have not been better pleased with any, than
those ingenious Pieces of Mr. Franklin you have favour’d me with
the Reading of.
I have Sometimes almost come to a Determination
to endeavour by your Assistance to get into an Acquaintance with
that Gentleman, a chief one in the Republick of Letters, whose
Parts, Industry and Learning are known in both Englands; and
devoted to the Welfare of Mankind.
But considering the Barreness of my Genius,
cramp’d by my low Circumstances and many other Disadvantages, I
have been discourag’d from pursuing the Same. It is doubtless fit
that I be contented with the Privilege of enjoying in Some Measure
the Benefit of the Correspondence between Him and yourself. I
remember the Satyrical Lines of Persius:
However, Dear Sir, I venture to trouble you
with two or three Thoughts that came into my Mind, in reading that
curious Manuscript, which you last favour’d me with the Sight of,
intitl’d, Physical and Meteorological Conjectures &c. which, if
you please you may communicate to that learned Gentleman, not so
much as real Objections to his Conjectures and Suppositions, but,
as imaginary Ones to be entirely removed by Him, when he revises
the Same.
“Air and Water mutually attract each other,”
saith that Gentleman: “Hence Water will dissolve in Air, as Salt in
Water.” I think, that he hath demonstrated, that the Supporting of
Salt in Water, is not owing to its Superficies being increas’d,
because the Specifick Gravity of Salt is not alter’d by dividing of
it, any more than that of Lead; Sixteen Bullets of which, of an
ounce each, weigh as much in Water as One, of a Pound. But yet,
when this came to be applied to the Supporting of Water in Air, I
found an Objection rising in my Mind.
In the first Place, I have always been loth to
Seek for any new Hypothesis, or particular Law of Nature to account
for any Thing that may be accounted for, from the known general and
universal Laws of Nature: It being an Argument of the infinite
Wisdom of the Author of the World to effect so many Things by one
general Law. Now I had thought that the rising and Support of Water
in Air might be accounted for from the general Law of Gravitation,
by only Supposing the Spaces occupied by the Same Quantity of Water
increas’d.
And with Respect to the Lead, I queried thus in
my own Mind, whether if the Superficies of a Bullet of Lead should
be increas’d four or five fold by an internal Vacuity, it would
weigh the Same in Water as before. I mean if a Pound of Lead Should
be formed into a hollow Globe empty within, whose Superficies
Should be four or five Times as big as that of the Same Lead, when
a Solid Lump, it would weigh as much in Water as before. I suppos’d
it would not. If this Concavity was filled with Water, perhaps it
might: If with Air, it would weigh, at lest, as much less as the
Difference between the Weight of the included Air and that of
Water.
Now altho’ this would do nothing to account for
the Dissolution of Salt in Water, the Smallest Lumps of Salt being
no more hollow Spheres, or anything of the like Nature than the
greatest, yet perhaps it may account for Water’s rising and being
Supported in Air. For we know that Such hollow Globles or Bubbles
abound upon the Surface of the Waters; which even by the Breath of
our Mouths we can cause to quit the Water, and rise in the Air.
These Bubbles, I us’d to suppose to be Coats of
Water containing within them Air rarified and expanded with Fire;
and that therefore the more Friction and Dashing there is upon the
Surface of the Waters, and the more Heat and Fire, the more they
abound.
And I us’d to think that altho’ Water be
specifically heavier than Air, yet such a Bubble filled only with
Fire and very rarify’d Air may be lighter than a Quantity of common
Air of the Same cubical Dimensions; and therefore ascend. For the
rarifi’d Air inclosd may more fall short of the Same Bulk of common
Air in Weight, than the watery Coat exceeds a like Bulk of common
Air in Gravity.
This was the Objection in my Mind, tho’, I must
confess I know not how to account for the watry Coat’s encompassing
the Air as above mention’d; without allowing the Attraction between
Air and Water, which the Gentleman Supposes. So that I don’t know
but that this Objection examin’d by that Sagacious Genius will be
an additional Confirmation of the Hypothesis.
The Gentleman observes, that “A certain
Quantity of Moisture should be every Moment discharg’d and taken
away from the Lungs,” and hence accounts for the Suffocating Nature
of Snuffs of Candles, as impregnating the Air with Grease, between
which and Water there is a natural Repellency, and of Air that hath
been frequently breathed in, which is overloaded with Water; and
for that Reason can take no more Air. Perhaps the same Observation
will account for the Suffocating Nature of Damps in Wells.
But then, if the Air can Support and take off
but Such a Proportion of Water, and it is necessary that Water be
so taken off from the Lungs, I queried with myself, how it is we
can breath in an Air full of Vapours, so full as that they
continually precipitate. Dont we see the Air overloaded, and
casting forth Water plentifully, when there is no Suffocation?
The Gentleman again observes, that “The Air
under the Equator and between the Tropicks being constantly heated
and rarified by the Sun, rises; it’s Place is Supplied by Air from
Northern and Southern Latitudes, which coming from Parts where the
Air and Earth had less Motion, and not Suddenly acquiring the
quicker Motion of the Equatorial Earth, appears an East Wind
blowing westward. The Earth moving from West to East and Slipping
under the Air.”
In reading this two Objections occur’d to my
mind.
First, that it is Said the Trade Wind doth not
blow in the Forenoon but only in the Afternoon.
Secondly, that either the Motion of the
Northern and Southern Air towards the Equator is so Slow as to
acquire almost the same Motion as the Equatorial Air, when it
arrives there, So that there will be no Sensible Difference, or
else the Motion of the Northern and Southern Air towards the
Equator is quicker and must be Sensible, and then the Trade Wind
must appear either as a South East or Northeast Wind: South of the
Equator a South East Wind; North of the Equator, a Northeast. For
the apparent Wind must be compounded of the Motion from North to
South or Vice versa, and of the Difference between it’s Motion from
West to East, and that of the Equatorial Air.
Sir. Notwithstanding these Objections I am
greatly pleas’d with that Manuscript: It is the most Satisfying
Solution of many Pheenomena of Nature I have seen. And ’tis not
because I am not charmed with the Piece, that I desire you to
present these Objections to that ingenious Gentleman; tis only to
give him an Opportunity to remove them. If you think it will be too
much Trouble to the Gentleman, to be so lengthy in them as I have
been, you may represent them as Short as you please. I am
&c.