The Complete Works in Philosophy, Politics and Morals of the late Dr. Benjamin Franklin, Vol. 2 [of 3]

By Benjamin Franklin

Page 167

contained was immediately tried by the thermometer, and found to be
70, which was six degrees colder than at the surface: the lead and
bottle were visible, but not very distinctly so, at the depth of
12 fathoms, but when only 7 fathoms deep, they were perfectly seen
from the ship. This experiment was thus repeated Sept. 11, when we
were in soundings of 18 fathoms. A keg was previously prepared with
a valve at each end, one opening inward, the other outward; this
was sent to the bottom in expectation that by the valves being both
open when going down, and both shut when coming up, it would keep
within it the water received at bottom. The upper valve performed
its office well, but the under one did not shut quite close, so
that much of the water was lost in hauling it up the ship's side.
As the water in the keg's passage upwards could not enter at the
top, it was concluded that what water remained in it was of that
near the ground, and on trying this by the thermometer, it was
found to be at 58, which was 12 degrees colder than at the surface.


_This last Journal was obligingly kept for me by Mr. J. Williams,
my fellow-passenger in the London Packet, who made all the
experiments with great exactness._




TO MR. O. N[36].

_On the Art of Swimming._


[No date.]

DEAR SIR,

I cannot be of opinion with you that it is too late in life for you
to learn to swim. The river near the bottom of your garden affords
a most convenient place for the purpose. And as your new employment
requires your being often on the water, of which you have such a
dread, I think you would do well to make the trial; nothing being
so likely to remove those apprehensions as the consciousness of
an ability to swim to the shore, in case of an accident, or of
supporting yourself in the water till a boat could come to take you
up.

I do not know how far corks or bladders may be useful in learning to
swim, having never seen much trial of them. Possibly they may be of
service in supporting the body while you are learning what is called
the stroke, or that manner of drawing in

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Text Comparison with Benjamin Franklin and the First Balloons

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Drafts of three of the letters are deposited in the University of Pennsylvania, but the existence of one letter and the whereabouts of another were unknown to the late Mr.
Page 1
Charles, Professor of experimental Philosophy at Paris.
Page 2
With great Respect, I am, Sir, Your most obedient and most humble Servant B.
Page 3
It contains 50,000 cubic Feet, and is supposed to have Force of Levity equal to 1500 pounds weight.
Page 4
B.
Page 5
) PASSY, Nov^r 21st, 1783 Dear Sir, I received your friendly Letter of the 7th Inst.
Page 6
As the Flame slackens, the rarified Air cools and condenses, the Bulk of the Balloon diminishes and it begins to descend.
Page 7
I was happy to see him safe.
Page 8
Thus the great Bulk of one of these Machines, with the short duration of its Power, & the great Expence of filling the other will prevent the Inventions being of so much Use, as some may expect, till Chemistry can invent a cheaper light Air producible with more Expedition.
Page 9
30, 1783 Dear Sir, I did myself the honour of writing to you the Beginning of last Week, and I sent you by the Courier, M.
Page 10
I hope they descended by Day-light, so as to see & avoid falling among Trees or on Houses, and that the Experiment was completed without any mischievous Accident which the Novelty of it & the want of Experience might well occasion.
Page 11
Les Voyageurs ont assure n'avoir eprouve que des Sensations agreables dans leur traversee.
Page 12
Il avoit perdu son air inflammable par le Robinet qu'on avoit laisse ouvert expres pour empecher l'explosion a trop grande hauteur.
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_Letter of November 30.
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16, "Bart.