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

By Benjamin Franklin

Page 31

great weight to a
considerable height in the air, &c."

[Illustration: (cross-section of a whirlwind)]

These accounts, the one of water-spouts, the other of a whirlwind,
seem, in this particular, to agree; what one gentleman describes as
a tube, black in the borders, and white in the middle, the other
calls a black cloud, with a pillar of light in it; the latter
expression has only a little more of the _marvellous_, but the thing
is the same; and it seems not very difficult to understand. When
Dr. Stuart's spouts were full charged, that is, when the whirling
pipe of air was filled between _a a a a_ and _b b b b_, Fig. I.,
with quantities of drops, and vapour torn off from the column W W,
Fig. II., the whole was rendered so dark, as that it could not be
seen thro', nor the spiral ascending motion discovered; but when
the quantity ascending lessened, the pipe became more transparent,
and the ascending motion visible. For, by inspection of the figure
in the opposite page, representing a section of our spout, with the
vacuum in the middle, it is plain that if we look at such a hollow
pipe in the direction of the arrows, and suppose opaque particles
to be equally mixed in the space between the two circular lines,
both the part between the arrows _a_ and _b_, and that between the
arrows _c_ and _d_, will appear much darker than that between _b_
and _c_, as there must be many more of those opaque particles in
the line of vision across the sides, than across the middle. It is
thus that a hair in a microscope evidently appears to be a pipe, the
sides shewing darker than the middle. Dr. Mather's whirl was probably
filled with dust, the sides were very dark, but the vacuum within
rendering the middle more transparent, he calls it a pillar of light.

It was in this more transparent part, between _b_ and _c_, that
Stuart could see the spiral motion of the vapours, whose lines on
the nearest and farthest side of the transparent part crossing each
other, represented smoak ascending in a chimney; for the quantity
being still too great in the line of sight through the sides of
the tube, the motion could not be discovered there, and so they
represented the solid sides of the chimney.

When the vapours reach in the pipe from the clouds near to the earth,
it is no wonder now to those who understand electricity, that flashes
of lightning should descend by the spout, as in that of Rome.


Last Page Next Page

Text Comparison with The Complete Works in Philosophy, Politics and Morals of the late Dr. Benjamin Franklin, Vol. 1 [of 3]

Page 5
267 Hypothesis, of the sea being the grand source of lightning, retracted.
Page 6
electrician and traveller.
Page 85
In September, 1752, Franklin entered upon a course of experiments, to determine the state of electricity in the clouds.
Page 86
clouds that strike into the earth.
Page 90
They were written by him to a gentleman, who had at that time published the idea of a college, suited to the circumstances of a young country (meaning New-York) a copy of which having been sent to Dr.
Page 107
Instead of endeavouring to allay this by a more lenient conduct, the ministry seemed resolutely bent upon reducing the colonies to the most slavish obedience to their decrees.
Page 108
The single legislature, and the.
Page 123
If they touch one another after exciting the tube, and drawing the fire as aforesaid, there will be a stronger spark between them than was between either of them and the person on the floor.
Page 126
[21] These experiments with the wheels, were made and communicated to me by my worthy and ingenious friend Mr.
Page 141
--Gilding on a new book, though at first it conducts the shock extremely well, yet fails after ten or a dozen experiments, though it appears otherwise in all respects the same, which we cannot account for[40].
Page 161
The circumstances of the breaking of the glass differ much in making the experiment, and sometimes it does not break at all: but this is constant, that the stains in the upper and under pieces are exact counterparts of each other.
Page 166
By the word _surface_, in this case, I do not mean mere length and breadth without thickness; but when I speak of the upper or under surface of a piece of glass, the outer or inner surface of the phial, I mean length, breadth, and half the thickness, and beg the favour of being so understood.
Page 186
_Electrical Kite.
Page 196
If it be asked, what thickness of a metalline rod may be supposed sufficient? In answer, I would remark, that five large glass jars, such as I have described in my former papers, discharge a very great quantity of electricity, which nevertheless will be all conducted round the corner of a book, by the fine filleting of gold on the cover, it following the gold the farthest way about, rather than take the shorter course through the cover, that not being so good a conductor.
Page 205
Withdraw it, and they will close.
Page 223
By this post I send to ****, who is curious in that way, some meteorological observations and conjectures, and desire him to communicate them to you, as they may afford you some amusement, and I know you will look over them with a candid eye.
Page 260
Page 296
_ 69, "that he can electrise a hundred men, standing on wax, if they hold hands, and if one of them touch one of these surfaces (the exterior) with the end of his finger:" this I know he can, while the phial is charging, but after the phial is charged I am as certain he cannot: that is, hang a phial, prepared for the Leyden experiment, to the conductor, and let a man, standing on the floor, touch the coating with his finger, while the globe is turned, till the electric matter spews out of the hook of the phial, or some part of the conductor, which I take to be the certainest sign that the phial has received all the electric matter it can: after this appears, let the man, who before stood on the floor, step on a cake of wax, where he may stand for hours, and the globe all that time turned; and yet have no appearance of being electrised.
Page 313
_Disputes_ between Franklin and his brother, to whom he was apprenticed, i.
Page 337