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The Philosophical transactions of the Royal society of London, from their commencement in 1665, in the year 1800 (Volume 8) online

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the axis of the great tube ab ; but it would conduct no electricity to the ball c;
though it carried it down very readily when full of water, though quite dry on
the outside.

Another small tube, open at both ends, which conducted no virtue to c
when dry, being only moistened a little by the breath in blowing through
it, carried down the virtue from a to c very strongly.

All this while the cat-gut strings e, e, received no electrical virtue.

Definition 1 . — A body electrical per se, is such a body in which one may
excite electricity by rubbing, patting, hammering, melting, warming, or any
other action on the body itself, as amber, sealing-wax, glass, resin, sulphur, &c.
besides many, if not all, animal substances.

Defin. 1. — A non-electrical, is such a body as cannot be made electrical by
any action on the body itself immediately ; though it is capable of receiving
that virtue from an electrical per se.

Observations. — 1 . When the air is full of moist vapours, electrics per se are
excited to electricity with very great difficulty, requiring to be often warmed,
and much rubbed ; as appears in exciting that virtue in glass, amber, wax, &c.



VOL. XLI.] PHILOSOPHICAL TRANSACTIONS. 355

2. In dry weather, especially in frosty weather, the electricals per se will
have their virtue excited with very little action on them; as appears by warming
a glass receiver, which, without any rubbing, will cause the threads of a down
feather, tied to an upright skewer, to extend themselves as soon as it is put
over the feather. Sometimes resin and wax exert their electricity by only being
exposed to the open air.

3. Electricals per se retain the virtue longest when kept near to, or inclosed
by, other electricals per se. Thus the rubbed tube will retain its virtue pretty
long in dry air, as appears by chasing a feather about the room very long with-
out new rubbing ; as also by lumps of resin and sulphur, &c. which have been
melted and poured into dry drinking glasses, keeping their virtue long, if kept
in those glasses, and wrapped in dry silk, or such sort of paper as will become
electrical by rubbing ; for as often as they are exposed to the air, they will
attract.

4. Electrics per se communicate their virtue to any of the non-electrical,
when brought near them ; in which case the non- electric attract and repel like
the electrics per se. Thus an iron bar suspended by a silken thread, a hair rope,
or a dry cat-gut, when an excited electric per se is brought near it, will both
attack and send out its effluvia to a non-electric held near it ; as appears in the
dark by the light coming out at the end of the bar.

5. An electric per se loses its excited virtue on communicating to the non-
electric ; and the sooner, the more of those bodies are near it. Thus in moist
weather the rubbed tube holds its virtue but a little while, because it acts on
the moist vapours that float in the air ; and if the rubbed tube be applied to
leaf-gold or brass, laid on a stand, it will act on it much longer, and more
strongly, than if the same quantity of leaf-gold be laid on a table, which has
more non-electric surface than the stand.

6. When a non-electric is suspended by, or only touches an electric per se,
it receives the properties of an electric per se from a rubbed tube or wax, &c.
This appears by the fire that flashes from the fingers of a man suspended by
hair-ropes, or who stands on a cake of resin, when he has received virtue from
the rubbed tube.

7. The virtue which a non-electric receives from a rubbed tube, runs on to
the most distant part of the suspended body, from the place where the tube is
applied, and seems to be collected there, from whence it flashes in the dark,
snaps, and exerts its attraction on the thread of trial ; though as the virtue
runs along, it sometimes shows itself in other parts of the suspended non-
electric.

zz2



356 PHILOSOPHICAL TRANSACTIONS. [aNNO 1739-

8. If a non-electric, while receiving the virtue from the rubbed tube, be made
to communicate with the floor of the room, or any other great non-electric
body, by a non-electric string, how small soever, though but a thread, the
virtue will not show itself, as it did before, at the extremities, where the flash
of light was seen.

g. If a non-electric be ever so large, when suspended, it will receive electri-
city from the rubbed tube. And if 5 or 6oo feet long, when the rubbed tube
is applied at one end, the bodies hanging at the other end will become electrical.
This has been tried by several people, as well as myself.

10. If a long non-electric string be fastened to an electric per se, and ex-
tended to a great distance, being supported by electric per se, to keep it from
touching the ground, all bodies fastened at the end of it will become electrical,
when the rubbed tube is applied at the other end, though the tube does not
touch it, but is only brought within 2 or 3 inches of it.

Note, This string we have before called the conductor of electricity, and the
cat-gut or silken strings, glass tubes, or whatever kept the long string from
touching the ground, supporters.

1 1 . If any of the supporters, mentioned in the last observation, be changed for
a non-electric supporter, the virtue will there be stopped, and taken away by that
supporter : but if that supporter be again supported by electrics per se, it will
only receive so much electricity as will impregnate it, and then the virtue will
go on to the end of the string, and impregnate the bodies fastened to it.

12. The non-electric receive the greatest virtue at the end of the string, and
most of all, if they are wet. But the electrics per se, if long bodies, as long
sticks of wax, and glass tubes, only become electric at the end next to the

string.

13. Electrics per se will become non-electrics, if they be wet, or only
moistened. Thus supporters that transmit the electricity immediately, stop it
when wet with a sponge, or when blown through, if open tubes. And if the
long electrics per se, hanging at the end of the conductor, be made wet, they
will become non-electrics, and strongly receptive of the virtue given by the
robbed tube at the other end of the string. All the 6 experiments mentioned
in the beginning of this paper, confirm this observation.

14. A non-electric having been impregnated with electricity, by the rubbed
tube, is repelled by it, till it has lost its electricity by communicating it to an-
other non-electric. Then being in its first state, it is again attracted by the
tube, which holds it till it has fully impregnated it; then it repels it again.
This is evident, by attracting a down feather by the tube in the air, and then
repelling it : so as to make it dance backwards and forwards to and from a finger



rOL. XL!.] PHILOSOPHICAL TRANSACTIONS. 357

held up at a foot or two from the tube. But the thing appears more plainly
from the following

Exper, 7. — Having rubbed the tube Tt, fig. 2, pi. 8, and with it attracted a
feather, the feather at t was repelled from the tube, whenever it was brought
near it ; but suddenly dipping the end t of the tube in water, the feather float-
ing in the air came to it again, and stuck to the end of the tube at t, or
near f.

In fair weather this experiment will not succeed, unless the tube be thrust
pretty deep into water, a foot at least ; but in moist weather an inch or two
will do.

Though animal substances be generally thought to be electric per se, yet it is
only when they are very dry : this is the reason why a living man suspended by
a hair-rope, or standing on a cake of resin, to receive electricity from the tube,
must be considered as a non-electric, by reason of the fluids of his body.

Of some Electrical Experiments, made at his Royal Highness the Prince of
fVales's Home at Cliefden, on Tuesday the 15th of April, 1738; where
the Electricity was conveyed 420 feet in a direct Line. By the Same.
N° 454, p. 209.

Having heard that electricity had been carried along a hempen string 5 or
600 feet, but having only seen it when the string was carried backwards and
forwards in a room by silk supporters. Dr. D. wished to dry it with a pack-
thread string stretched out at full length; for which purpose having joined a
cat-gut string of 6 feet long, he fastened it to the inside of a door in the suite
of rooms at Cliefden ; and having also tied another cat-gut, like the first, to
the other end of the string, he tied it up to the inside of the door at the other
end of the house ; but at the place where the packthread was joined to the cat-
gut, he left a foot and a half of packthread hanging down, and fastened to it a
lignum vitae handle of a burning-glass. Then applying a rubbed tube at the other
end of the string, he made the electricity run to the lignum vitae, but with some
difficulty, which he attributed to the size, being an animal substance, that still
stuck to the packthread as it was new ; therefore he caused the packthread to
be wet with a sponge from one end to the other, to wash off the size : then was
the electricity from the tube communicated very soon and very strongly ; for
the thread of trial was drawn by the lignum vitae at the distance of a foot.

Afterwards having joined more packthread together, he mnde a string of 420
feet long, one end of which was fastened, by the interposition of cat-gut as be-
fore, to the iron gates in the garden, before the house, and the end which had



358 PHILOSOPHICAL TRANSACTIONS. [aNNO 1739-

the lignum vitae handle, to the upper part of the door next to the back-side of
the house in a large drawing-room, taking care that the string came through
the middle of the opened doors through which it passed ; and to prevent this
string dragging on the ground, three pieces of cat-gut held across by two men,
at equal distances from the ends, and from each other, supported it. The
string was altogether dipped in a pail of water, before the experiment ; but
great care was taken, that the cat-gut should not be wet.
. Then he applied the rubbed tube at the end in the garden, while an assistant
held the thread of trial near the handle abovementioned, which thread was
strongly attracted, though the wind was very high, and blowed in the contrary
direction to that in which the electricity ran along.

He first tried the experiment with the packthread dry, but then it would not
dp at that distance. The weather was moist when he made the experiment.

Botanical Observations, exhibiting accurate Descriptions of some Plants. By
Paul Henry Gerard Moehring, M. D. N° 454, p. 211.

This paper contains a description of 6 plants; viz. 1. Salicornia ramis clavatis,
squamis articulorum adpressis. — 2. Verbascum foliis cordatis crenatis acutis
glabris : floralibus ternis. — 3. Senecio foliis pinnatifidis lacinulatis : laciniis
omnibus laxis patentissimis linearibus acutis. — 4. lUecebrum Linn. Corollar.
gen. 947. Rupp. .Ten. 79- Corrigiola Dillen. Giss. Supplem. adpend. 167. —
5. Ruppia foliis linearibus obtusis. — 6. Hippuris. Linn. gen. 1. —

Observations on an jinthelium, seen at fVtrtemberg, Jan. 18, n. s. 1738. By

J. F. JVeidler. N° 454, p. 221.

An Occultation of Aldebaran by the Moon, Dec. 23, 1738, n. s. Observed by
Christfried Kirch, Astronomer Royal at Berlin. N° 454, p. 223.

Immersion at 6^ 31*" 54' correct time.

Emersion 7 33 33

The same Occultation, observed at Wittemberg. By J. F. Weidler, F. R. S.

N° 454, p. 225.

Immersion &" 27™ 35*

Emersion 7 29 20

Duration 1 l 45



I



VOL. XLI.] PHILOSOPHICAL TRANSACTIONS. " 369

A Solar Eclipse observed at fVtrtemberg, July 24, o. s. 1 739. By J. F. fVeidler,







F. R. S. N° 454, p. 226.


4"

4

5

5

6


15"
53
24
50

27


' 30* P. M. Beiginning of the eclipse.
40 .... 6 digits eclipsed.
40 .... 9 digits, the greatest obscuration
30 .... 6 digits when decreasing.
20 . . .,. End of the eclipse.



Of a terrible Whirlwind, which happened at Come- Abbas in Dorsetshire, Oct. 30,
1731. By Mr. J. Dorby. N° 454, p. 229.

On Saturday Oct. 30, about a quarter before one in the night, there hap-
pened at Corne-Abbas, Dorsetshire, a very sudden and terrible wind whirl-pufF,
as Mr. D, calls it : some say it was a water-spout, and others a vapour or ex-
halation from the earth. It began on the south-west side of the town, passing
directly to the north-east, crossing the middle of the town in breadth 200 yards.
It stripped and uncovered tiled and thatched houses, rooted trees out of the
ground, broke others in the midst, of at least a foot square, and carried the
tops a considerable way. The sign of the new inn, a sign of 5 feet by 4, was
broken off 6 feet in the pole, and carried cross a street of 40 feet breadth, and
over an opposite house. It took off and threw down the pinacles and battle-
ments of one side of the tower ; by the fall of which, the leads and timber of
great part of the north aile of the church were broken in. The houses of all the
town were so shocked, as to raise the inhabitants. No hurt was done but only
across the middle of the town in a line. Nor no life lost. No other parts of
the neighbourhood or country so much as felt or heard it. It is supposed by
the most judicious, that it began and ended within the space of two minutes.
It was so remarkably calm a quarter after 12, that the exciseman walked through
two streets, and turned a corner, with a naked lighted candle in his hand, un-
molested and undisturbed by the air ; and as soon as over, a perfect calm, but
was soon followed by a surprising violent rain.

Of Letters found in the Middle of a Beech. By J. Theod. Klein, Secretary of
Dantzick, F. R. S. N" 454, p. 231.

In the year 1727, a beech-tree was felled near Elbing, for the domestic use
of John Maurice Moeller, then post-master of Elbing, now secretary of his
native city. The trunk being sawed into pieces, one of these, 3 Dantzic feet



3jSb PHILOSOPHICAL TRAKSACTIONS. [aNNO \73Q.

6 inches long, cleft in the house, discovered several letters in the wood, about
1 inch and a half from the bark, and near the same distance from the centre of
the trunk. Two of these, db, show their old bark smooth and sound. The
wood lying between the letters and the bark of the trunk, as well as that be-
tween the letters and the heart of the tree, is likewise solid and sound, bearing
not the least trace of letters. The characters bd, being somewhat hollow, re-
ceive the bark of the letters db.

The same letters are seen in the bark of the tree, only that they are partly
ill shaped, partly almost effaced ; whereas those within bear a due proportion,
as if done with a pencil.

It is an ancient custom to cut nan)es, and various characters, on the rinds
of trees, especially on such as are smooth. That this has happened to our
beech, the mere inspection of the bark sufficiently shows. An incision made,
the tubuli conveying the nutritious juice, and the utriculi in which it is pre-
pared, are divided and lacerated, and more of them, as the incision was made
deeper and wider : and consequently the sap is not carried on in the circula
tion, but extravasated and stopped at the wounds. Hence the origin of the
characters in the bark and wood.

Now as a new circle of fibres grows yearly on the tree, between the wood
and bark, a number of these may, in a process of years, more and more sur-
round the engraved characters, and at length cover them. And this number
was the greater in our beech, on account of better than half a century elapsed
since the incision, which was made in the year 1672, as appears on the outside
of the bark. But while new circles of fibres are successively added, the tunicle
or skin of the bark is broken each time, and the utriculi extended and dilated.

M. Klein also mentions several other instances of the same kind, and ac-
counted for in the same manner, as treated of by different authors ; viz. Solo-
mon Reisel, John Meyer, Luke Schroeck, John Chrit. Gottwald, John James
Scheuchzer, and John Melch. Verdries.

On the Ejects of Thunder on Trees, and on a large Deer's Horn found in the
Heart of an Oak. By Sir John Clark, one of the Barons of his Majesty's Ex-
chequer in Scotland, and F. R. S. N" 454, p. 235.

Being lately in Cumberland, Sir J. C. there observed three curiosities in
Winfield-Park, belonging to the Earl of Thanet. The first was a huge oak,
at least 60 feet high, and 4 in diameter, on which the last great thunder had
made a very odd impression; for a piece was cut out of the tree, about 3 inches
broad, and 2 inches thick, in a straight line from top to bottom. The second



VOL. XLI.] PHILOSOPHICAL TRANSACTIONS. il(i|

was, that in another tree of the same height, the thunder had cut out a piece
of the same breadth and thickness, from top to bottom, in a spiral line, making
3 turns about the tree, and entering into the ground above 6 feet deep. The
third was the horn of a large deer found in the heart of an oak, which was dis-
covered on cutting down the tree. It was found fixed in the timber with
large iron cramps ; it seems therefore, that it had at first been fastened on the
outside of the tree, which in growing afterwards had inclosed the horn. In
the same park Sir John saw a tree 13 feet diameter.

Remarks on the foregoing. By the Editor, Dr. Mortimer. N° 454, p. 236.

This horn of a deer, found in the heart of an oak, and fastened with iron
cramps, is one of the most remarkable instances of this kind, it being the largest
extraneous body we have any where recorded, thus buried, as it were, in the
wood of a tree. If J. Meyer, and J, Pet. Albrech had seen this, they could
not have imagined the figures seen by them in Beech-trees to have been the
sport of nature, but must have confessed them to have been the sport of an
idle hand. To the same cause are to be ascribed those figures of crucifixes.
Virgin Marys, &c. found in the heart of trees ; as, for example, the figure of
a crucifix, which I saw at Maestricht, in the church of the White Nuns of
the order of St. Augustin, said to be found in the heart of a walnut-tree, on
its being split with lightning. And it being usual in some countries to nail
small images of our Saviour on the cross, of Virgin Marys, &c. to trees by the
road-side, in forests, and on commons ; it would be no greater a miracle to
find any of these buried in the wood of the tree, than it was to find the deer's
horn so lodged.

Sir Hans Sloane, in his noble museum, has a log of wood brought by Mr.
Cunningham from an island in the East-Indies, which, on being split, exhibited
these words in Portuguese, da boa ora. i. e. Det [Deus] bonam horam.

On the Eruption of Vesuvius, in May 1737- By N. M. d!Aragona, Prince of
Cassano, and F. R. S. N° 455, p. 237,

Mount Vesuvius is about 7 miles distant from Naples, and 4 miles from the
sea. It rises in the middle of a large plain ; and the foot of it begins from the
sea-coast, which growing gradually higher, reaches the first plain, to which
one can easily ride on horseback. The figure of the plain is nearly circular,
being about 5 miles in diameter, and half a mile perpendicular height above
the level of the sea. This is the basis of the mountain, out of which arises
another, called Monte Vecchio, whose perpendicular height is about 4O0

VOL. VIII. 3 A



362 PHILOSOPHICAL TRANSACTIONS. [aNNO 1739.

paces, and its top little less than 2 miles in circumference, of an irregular figure.
The top, before the year 1 631, was of the form of a basin, but all surrounded
with aged oaks, and vastly large chestnut- trees, the fruit of which afforded
food sufficient for a number of cattle. In the bottom, a cavern was observed,
into which people descended above 200 paces, by difficult and interrupted paths :
this was the ancient mouth, which for a long time had constantly cast up great
quantities of bituminous matter, and had at the same time burnt a considerable
part of the neighbouring country, cultivated by the inhabitants round the hill.

Concerning the eruptions that have happened heretofore, they are very
numerous, as well ancient as modern. Of the first, several are mentioned by
Berosus Chaldaeus, Pobybius, Strabo, in the time of Augustus, Diodorus
and Vitruvius; and in Trajan's reign the name of the mountain became
more famous by the death of Pliny. From that time it is thought the
eruptions were less frequent, down to the year IISQ; when, after a con-
siderable eruption, it continued quiet somewhat less than 5 centuries ; so
that the horrid remembrance of the past ruins was pretty well obliterated
out of the minds of the neighbouring inhabitants ; who, vainly flattering them-
selves with hopes, that the infiammable matter was spent, planted the whole
district round the mountain, which, by its fertility, became the delight of these
parts. But they found themselves deceived and frustrated in their expectations:
for in the year 1 631, during 6 months space, continual rumblings were heard,
and shocks of earthquakes felt : and afterwards, in the month of December,
a dreadful fiery eruption happened, which first blew up part of the mountain
into the air, in a terrible manner, and then vomited out water, ashes, stones
and fire; inundating almost the whole country around to the sea, and for above
7 miles in breadth, with the dreadful loss of more than 4000 people. After
which the mountain became silent, and remained considerably diminished in
its height, from what it had been before.

It continued quiet for 2Q years ; but having rekindled in l66o, its fire filled
the whole capacity of the immense hollow, which remained since the year l63l ;
whence, after several less eruptions, a new inountan appeared in l685.

In 1707, not only the inhabitants of the neighbourhood, but also the whole
city of Naples, were put into great terror, on account of the frequent noise
and shocks, the fire seen on the top of the mountain, with a vast quantity
of ashes, which issuing out with impetuosity, were dispersed all over our he-
misphere, and darkened the light of the sun during one whole day. These were
all manifest signs of the impending desolation : and yet this dreadful day,
which had portended so much mischief, was beyond expectation, and to our
great astonishment, followed by another as pleasant as could be desired : for



VOL. XLI.J PHILOSOPHICAL TKAN8ACTIONS. 363

the air was quite serene, and clear of ashes; and on the mountain there wap
no other appearance besides that of a little smoke.

In the year 1724, the quantity of ashes and stones, thrown from the top of
the mountain, was so heaped from the bottom up to the edge of the ol
mountain, that the whole space from the old hill to the new, appeared but one
continued mountain.

In 1730, there was another eruption of Vesuvius, though very inconsiderable
in respect of the last.

This present year 1737, to the month of May, the mountain was never
quiet : sometimes emitting great quantities of smoke, at other times red-hot
stones ; which, for want of a sufficient impelling force, fell on the same
mountain. In the beginning of May, a smoke only was seen to issue from
the open mouth at the top; and from the 10th to the IQth, subterraneous
rumbling noises were heard.

On the 19th, fire was seen to burst out in thick black clouds ; and the same
day there were several loud reports, returning quicker towards the evening :
And still more on Sunday night, when there constantly appeared a very great
smoke mixed with ashes and stones : and the neighbourhood felt some shocks,
like those of a weak earthquake.

On Monday the 20th, at the 13th hour, the mountain made so loud an ex-
plosion, that the shock was strongly felt even in the cities 12 miles round.
Black smoke, intermixed with ashes, was seen suddenly to rise in vast curling
globes ; which spread wider, as it moved farther from the basin. The explo-
sions continued very loud and frequent all this day, shooting up very large
stones through the thick smoke and ashes, about a mile high, to the horror of
the beholders, and the danger of all the neighbouring buildings.

At the 24th hour of the same Monday, May 20, amidst the noise and
dreadful shocks, the mountain burst on the first plain, a mile distant ob-
liquely from the summit, and there issued from the new opening a vastly
large torrent of fire; whence, by the quantity of fire incessantly thrown
up into the air, at a distance all the south side of the mountain seemed
in a fiaine. The liquid torrent flowed out of the new vent, rolling along
the plain underneath, which is above a mile long, and near 4 miles broad ; and
in its way it spread very speedily near a mile wide ; and by the 4th hour of the



Online LibraryRoyal Society (Great Britain)The Philosophical transactions of the Royal society of London, from their commencement in 1665, in the year 1800 (Volume 8) → online text (page 42 of 85)