circle. Now the aperture of the eye, through which the light passes,
does not exceed one-tenth of an inch diameter, and the portion of
the lesser circle, which corresponds to this small portion of the
greater circle, must be proportionably, that is, 1027709337600 times
less than one-tenth of an inch; and yet this infinitely small point
(if you will allow the expression) affords light enough to make it
visible four miles; or, rather, affords light sufficient to affect
the sight at that distance.
The smallness of the animalcula is no objection then to this
conjecture; for supposing them to be ten thousand times less than the
_minimum visibile_, they may, notwithstanding, emit light enough to
affect the eyes, and so to cause the luminous appearance aforesaid.
This conjecture I send you for want of something better ****.
 I. Badoin. _Editor._
TO MR. P. F. IN NEWPORT.
_On the Saltness of Sea-Water._
_London, May 7, 1760._
**** It has, indeed, as you observe, been the opinion of some very
great naturalists, that the sea is salt only from the dissolution
of mineral or rock-salt, which its waters happened to meet with.
But this opinion takes it for granted that all water was originally
fresh, of which we can have no proof. I own I am inclined to a
different opinion, and rather think all the water on this globe was
originally salt, and that the fresh water we find in springs and
rivers, is the produce of distillation. The sun raises the vapours
from the sea, which form clouds, and fall in rain upon the land, and
springs and rivers are formed of that rain. As to the rock-salt found
in mines, I conceive, that instead of communicating its saltness to
the sea, it is itself drawn from the sea, and that of course the sea
is now fresher than it was originally. This is only another effect of
nature's distillery, and might be performed various ways.
It is evident from the quantities of sea-shells, and the bones and
teeth of fishes found in high lands, that the sea has formerly
covered them. Then, either the sea has been higher than it now is,
and has fallen away from those high lands, or they have been lower
than they are, and were lifted up out of the water to their present
height, by some internal mighty force, such as we still feel some
remains of, when whole continents are moved by earthquakes. In
either case it may be supposed that large hollows or valleys among
hills, might be left filled with sea-water,
Farther reflection confirmed me in the design of leaving Boston, where I had already rendered myself an object of suspicion to the governing party.Page 67
He became a very respectable merchant, and one of our provincial judges.Page 68
My hopes of success, which I imparted to him, were founded on the circumstance, that the only paper we had in Philadelphia at that time, and which Bradford printed, was a paltry thing, miserably conducted, in no respect amusing, and which yet was profitable.Page 77
Stuber, of Philadelphia.Page 144
--The detached particles of water then repelled from the electrified surface, continually carry off the fire as it is collected; they rise and form clouds, and those clouds are highly electrified, and retain the fire till they have an opportunity of communicating it.Page 156
But the force with which the electrified body retains its atmosphere by attracting it, is proportioned to the surface over which the particles are placed; _i.Page 179
--Supposition of a Region of electric Fire above our Atmosphere.Page 180
Frequently, in a variety of experiments, though we miss what we expected to find, yet something valuable turns out, something surprising, and instructing, though unthought of.Page 192
If _more_ squeezed and condensed, some of the water will come out of its inner parts, and flow on the surface.Page 198
Too great charge might, indeed, kill a man, but I have not yet seen any hurt done by it.Page 220
Now light (as astronomers have demonstrated) is about six minutes passing from the sun to the earth; a distance, they say, of more than eighty millions of miles.Page 227
Suppose a tube of any length open at both ends, and containing a moveable wire of just the same length, that fills its bore.Page 253
that of _conducting_ the lightning.Page 281
The reason is, that while the bar was hot, the magnetic fluid which it naturally contained was easily forced from one extremity to the other by the magnetic virtue of the earth; and that the hardness and condensation, produced by the sudden cooling of the bar, retained it in this state without permitting it to resume its original situation.Page 297
These persons placed themselves one on each side of me, while I stood on a cake of wax, and took hold of the hook of that phial which was held by its coating (upon which a spark issued, but the phial was not discharged, as I stood on wax) keeping hold of the hook, I touched the coating of the phial that was held by its hook with my other hand, upon which there was a large spark to be seen between my finger and the coating, and both phials were instantly discharged.Page 309
_Coal_, sea, letter on the nature of, ii.Page 329
instance of one set up by Franklin at Philadelphia, 86.