the under region of the air, and make the upper descend,
whence sudden and wonderful condensations may take place, and make
It seems to me, that the manner of their appearance and procedure,
favour the notion of a descent.
More or less of a cloud, as I am informed, always appears over the
place first; then a spattering on the surface of the water below; and
when this is advanced to a considerable degree, the spout emerges
from the cloud, and descends, and that, if the causes are sufficient,
down to the places of spattering, with a roaring in proportion to the
quantity of the discharge; then it abates, or stops, sometimes more
gradually, sometimes more suddenly.
I must observe a few things on these particulars, to shew how I think
they agree with my hypothesis.
The preceding cloud over the place shews condensation, and,
consequently, tendency downwards, which therefore must naturally
prevent any ascent. Besides that, so far as I can learn, a whirlwind
never comes under a cloud, but in a clear sky.
The spattering may be easily conceived to be caused by a stream of
drops, falling with great force on the place, imagining the spout
to begin so, when a sudden and great condensation happens in a
contracted space, as the Ox-Eye on the coast of Guinea.
The spout appearing to descend from the cloud seems to be, by the
stream of nearly contiguous drops bringing the air into consent,
so as to carry down a quantity of the vapour of the cloud; and the
pointed appearance it makes may be from the descending course being
swiftest in the middle, or centre of the spout: this naturally
drawing the outer parts inward, and the centre to a point; and
that will appear foremost that moves swiftest. The phenomenon of
retiring and advancing, I think may be accounted for, by supposing
the progressive motion to exceed or not equal the consumption of
the vapour by condensation. Or more plainly thus: the descending
vapour which forms the apparent spout, if it be slow in its progress
downwards, is condensed as fast as it advances, and so appears at a
stand; when it is condensed faster than it advances, it appears to
retire; and _vice versa_.
Its duration, and manner of ending, are as the causes, and may vary
by several accidents.
The cloud itself may be so circumstanced as to stop it; as when,
extending wide, it weighs down at a distance round about, while a
small circle at the spout being exonerated by the discharge ascends
and shuts up the passage. A new determination of wind
At the same time that the wire and top of the bottle, &c.Page 3
Touch the wire of the phial repeatedly with your finger, and at every touch you will see the.Page 6
If you would have the whole filletting round the cover appear in fire at once, let the bottle and wire touch the gold in the diagonally opposite corners.Page 7
--Or fix a needle to the end of a suspended gun-barrel, or iron rod, so as to point beyond it like a little bayonet; and while it remains there, the gun-barrel, or rod, cannot by applying the tube to the other end be electrised so as to give a spark, the fire continually running out silently at the point.Page 10
_ _SIR_, s 1.Page 12
Since we are of opinion, that there is really no more electrical fire in the phial after what is called its _charging_, than before, nor less after its _discharging_; excepting only the small spark that might be given to, and taken from, the non-electric matter, if separated from the bottle, which spark may not be equal to a five hundredth part of what is called the explosion.Page 14
About thirty _radii_ of equal length, made of sash glass cut in narrow strips, issue horizontally from the circumference of the board, the ends most distant from the center being about four inches apart.Page 19
And this form it takes, because it is attracted by all parts of the surface of the body, tho' it cannot enter the substance already replete.Page 33
But there is a small portion between I, B, K, that has less of the surface to rest on, and to be attracted by, than the neighbouring portions, while at the same time there is a mutual repulsion between its particles and the particles of those portions, therefore here you can get it with more ease or at a greater distance.Page 35
Thus in the present case, to know this power of points, may possibly be of some use to mankind, though we should never be able to explain it.Page 36
The horizontal motion of the scales over the floor, may represent the motion of the clouds over the earth; and the erect iron punch, a hill or high building; and then we see how electrified clouds passing over hills or high buildings at too great a height to strike, may be attracted lower till within their striking distance.Page 38
Reading in the ingenious Dr.Page 44
When the glass has received and, by its attraction, forced closer together so much of this electrified fluid, as that the power of attracting and condensing in the one, is equal to the power of expansion in the other, it can imbibe no more, and that remains its constant whole quantity; but each surface would receive more, if the repellency of what is in the opposite surface did not resist its entrance.Page 45
The surface that has been thus emptied by having its electrical fluid driven out, resumes again an equal quantity with violence, as soon as the glass has an opportunity to discharge that over-quantity more than it could retain by attraction in its other surface, by the additional repellency of which the vacuum had been occasioned.Page 46
But thus it may: after every stroke, before you pass your hand up to make another, let the second person apply his finger to the wire, take the spark, and then withdraw his finger; and so on till he has drawn a number of sparks; thus will the inner surface be exhausted, and the outer surface charged; then wrap a sheet of gilt paper close round the outer surface, and grasping it in your hand you may receive a shock by applying the finger of the other hand to the wire: for now the vacant pores in the inner surface resume their quantity, and the overcharg'd pores in the outer surface discharge that overplus; the equilibrium being restored through your body, which could not be restored through the glass.Page 47
Hence we see the.Page 51
Page 25, line 10.