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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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cross containing tlie axis, ggg, bj a pricked circle, denotes a narrow ring of
thick blanketing, which (by pressing against the outside case, while it is fixed
to the outside of the flat of the wheel) makes the passage into the wheel tight.
HHH is another circle of blanketing, likewise fixed to the outside of the wheel,
and rubbing against the case ; that the air violently driven against the inner cir-
cumference of the case, may have no exit, but at the blowing-pipe at b.

On the outside of the other flat of the wheel, where the handle is fixed, is
a ring of blanketing, like hhh, opposite to it, but none opposite to ggg; be-
cause the wood there is not open, but comes home close to the axis.

Fig. 3 gives a vertical section of the wheel and case, a little forward of the
flxis, drawn to a scale twice as large as that of the other two figures. Aa the
axis, supported by the irons A, a, cylindrically hollowed, except the upper part,
where a pin keeps in the axis, bd the case with the sucking-pipe sa. ea the
prop for one end of the axis. 1, 2, the opening into the wheel, gg the emi-
nence of the wood, to which is fixed the small ring of blanketing. The four
black marks, one of which is near h, represent the sections of the two other
rings of blanketing.

A Calculation of the Velocity of the Air moved by the new-invented Centrifugal
Bellotvs, of 7 Feet in Diameter, and 1 Foot thick within. By J. T. Desa
guliers, F. R. S. N° 437, P- 44.

When the wheel revolves on its axis, which is performed in this machine
every revolution in about half a second, the air may be considered as divided
into as many concentric circumferences, as there are particles of air contained
between the least and the greatest circle ; consequently the centrifugal forces
will be as the radii, that is, in an arithmetical progression.

Let R = radius of the greatest circle 3.5 feet,

r = radius of the least circle O.75,

m = radius of the middle circle . •• 2. 125 = 4.R -j- ^r,

t; = the velocity, or space described in a second, "S

in the middle circle, on the supposition that .2Q.ll,
the wheel makes two revolutions in a second j
s = space described in a second by the action of



* = the space that a particle of air, receding from the centre, would
describe in a second, by the action of the centrifugal force at the
circumference of the middle circle.
Then 2m'.v::v:s\ therefore ^ = «, by Huygens's rule. Let g and c.


express the force of gravity, and the centrifugal force at the middle circle.
Since the spaces described in the same time, by the action of two forces, are

as those forces, s : 5 :: g : c, and — := c; then substituting in this expression, -—
instead of s, we have - — = c; and putting -^r + t'" instead of its equal m,
-. — ■—: = c. So that the ratio of gravity to the centrifugal force, at the

middle circle, is that of g to '^ , or that of 1 to —^ ; which

(R + r) X s' (a + r) X s '

being multiplied by the number of the revolving circles u — r, gives for the
pressure of the column of air r — r, proceeding from gravity, r — r, and the

pressure proceeding from the centrifical forces ■ ■— , where r — r being

a factor common to both, may be thrown out of the expression; and since the
velocities produced from different pressures, are as the square roots of the
pressures, the velocity gravity would give from the natural weight or pressure
of R — r, will be to the velocity the same column would have from the pres-
sure occasioned by the centrifugal force, as ^Z J , or 1 , to t/- r .

•' ° '(R + r)xs

Lastly, since the velocity proceeding from the action of gravity, on a column
= R — r, is always a known quantity, it may be called = a, equal in this case
to 15,38 feet per second, and consequently the velocity proceeding from the

centrifugal force will be a X /: c , or av X \^ , — :— r , or ,■ , - =^;

^ ' (R + r) X s- (r + r) X s' v(r -|. r) x s

1 5-38 X 26 71

that is, in this machine, . .'. — = 40.67 feet per second. And if we add

to this, the velocity of the outer circle in the tangent of which the air escapes,
which, in the supposition we made of two revolutions in a second, is 44 feet
per second, we shall have = 93.67 feet per second.

Note. — This calculation supposes the bore of the sucking-pipe sufficient to
furnish as much air as would escape, according to this velocity ; but in this
machine the sucking-pipe being no larger than the ajutage or blowing pipe,
the velocity proceeding from the pressure occasioned by the centrifugal force,
and from the velocity in the tangent, which may be represented by a column
of air of sufficient height to give the velocity of 93.67 feet, which is 145. 882
feet, must be divided into two equal parts, one half employed in sucking, and
the other in blowing; therefore the half of 145.882 feet, which is 72-941 feet,
will represent the height of a column of air, that would occasion the same
pressure with which the centrifugal force and the circular motion act in this
machine; and a column of this height producing a velocity of 68.53 feet per
second. This number will express the velocity with which the air is sucked
into the wheel; and the same number will also express the velocity of the air


out of the blower, proceeding from the centrifugal force, and the circular velo-
city of the outer circle, which is the real velocity of the stream of air out of
the blower of this machine, viz. 68.53 feet per second, which is at the rate of
a mile in about 77 seconds, or about 7 miles in Q minutes.

The Uses of the foregoing Machine. By the same. N° 437, P- 47.

Besides the uses of this machine for sick rooms, for prisons, or large assem-
blies, for warming, cooling, or perfuming any chambers at a distance, it may
also serve in a man of war, to takeaway the foul air between decks, occasioned
by the number of men in the ship, and to give them fresh air in a few minutes.
In every part of the vessel, every foul hole may be rendered wholesome, and
even the stench and foul air from the surface of the bulge water may be carried
oft". Also for mines the machine must prove of excellent use; for as the
damps, either fulminating, which taking fire, destroy the men and ruin the
works, or arsenical, which kill by their poisonous nature, are some specifically
lighter, and some specifically heavier than common air, this centrifugal wheel
can in a little time drive down air through wooden trunks, or launders, of 7
inches bore, in such quantities into the deepest mines, as to cause all the light
damp to come out at the top of the pit; or, by only altering two sliders, suck
away all the heavy poisonous damp, while wholesome air goes down from above
ground into the pit, so as to fill all the subterraneous caverns with fresh and
wholesome air.

Likewise a great many of the difiiculties which attend the carrying on sub-
terraneous passages, for the conveyance of water from mines, called soughs,
adits, or drifts, may be removed by the help of this wheel ; for the fresh air
may be driven in a very little time to the place where the men are at work,
though at the distance of 2, 3, or 4 miles, and therefore also to any interme-
diate space; whereas the practice now is, either to make a double drift, with
communications between the two for the circulation of the air, or to sink per-
pendicular shafts or pits, from the top of the hill over the adit: both which
methods are very expensive, and inferior to the application of this machine.

The Case of a Cataleptic Woman. By Richard Reynell, Jpolhecary, London.

N" 437, p. 49.

Ann Billiard, a servant, about 21 years of age, had been for some time irre-
gular in her menses, and very much afflicted for the loss of a friend. July
10, 1730, she complained of a pain in her head, sickness in her stomach, with
a general disorder ; and took Gascoign's powder for a sweat; next morning.


July Jl, about p o'clock, she was found in bed, senseless, stiff, and void of
feeling, with her eyes shut, and seemed to be dead. When Mr. R. came, he
found her in a true cataleptic fit, senseless, without motion, her limbs very
stiff, but warm, and not easy to be bent; but in whatever posture any limb was
put, it continued in the same, whether erect or reclined; her respiration was
good, but her pulse low and irregular; she had no calchings, or convulsive
motions, but could not, by any means used, be brought to herself. A vein
was opened in the arm, and 12 oz. of blood were taken away; she bled freely,
and came a little to herself, but could not speak. Mr. R. then gave her some
volatile and anti-spasmodic medicines. In a few hours she came to herself.
She complained of a dizziness in her head, with a violent pain in the fore part
of it, and sickness in her stomach, and was a little feverish. H«/ gave her a
vomit at 4 o'clock in the afternoon, which worked kindly, and she seemed
relieved by it. About 6 in the evening another tit returned, much in the same
manner as before; but she soon came out of it, and then took the medicines
with the volatile salt of hartshorn, as before. Mr. R. moreover applied a large
blister to her back, and two more to her arms; about Q the same evening she
had a strong convulsion fit, with catchings, grinding of the teeth, and a great
tremour; neither of which she had had before: she had a stool the preceding
night, but none that day. He gave her a draught with tinct. hier. at night
going to rest; she continued taking the volatile medicines, &c. every 4 hours.
July 12, she had been light-headed all night, with little or no rest; the blisters
were dressed, which discharged plentifully, and the tincture had given her 3
stools in the night, which had made her a little faint; her pulse was low, and
her water pale. Mr. R. saw her in the evening, when she had slept pretty
well, with which she was refreshed; the pain in her head but little, her stomach
easy, and he found her in every respect better. The medicines were continued.
July 13, in the morning, Mr. R. found her head easy, her water higher co-
loured; she was allowed broth, and food of easy digestion, which agreed very
well with her. She sat up in the afternoon, but was faint, and her head giddy;
but when in bed she was better. She had no stool that day. The volatile me-
dicines, &c. were continued with a purge the next morning. July 14, the
purge worked 5 times; she eat a light dinner, and was easy; but on walking
about the room, her head was giddy, and she trembled very much ; but when
in bed, she was better. Mr. R. gave her a draught with sp. c. c. and tinct.
castor. July 15, she complained, when up, of a numbness in her legs, and a
pricking in them, like what happens when the legs are what we commonly call
asleep: her appetite was better, and she was in every respect mended. Mr. R,
then gave her some medicines composed of valer. castor, asafoetida, &c. The


blisters were kept running as long as could be; and when they were dried up,
Julv 19, he gave her the same purge as before. July 22, she had continued
very well, without any return of a fit; but on cutting an issue in her arm, she
fell into a third fit, in which she continued near 1 hours; but then came to
herself, and was well that evening. July 29 the purge was repeated. August
6 she complained of ,a pain in her head, sickness in her stomach, and some
days before she had the menses, and had vomited near 1 lb. of blood, and was
costive; Mr. R. then advised her to take 2 spoonfuls of tinct. sacra every, or
every other night, going to bed, as she found it necessary, and 40 of the fol-
lowing drops: R spt. c. c. opt. jiij. tinct. helleb. nigr, 3V. to be taken twice a
day in camomile tea. She took these medicines about 3 weeks, which an-
swered expectation, and he left her well. He saw her about 12 months after,
and she told him she had continued very well ever since.

Sennertus, Med. Pract. lib. 1. c. 30, says, that a catalepsy is so rare a case,
that it is supposed hardly one physician in a hundred has seen a cataleptic
patient; so that when this disease occurs, its history is carefully to be noted.

Thoughts on the Operation of the Fistula Lacrymalis. By Francis Joseph
Hunauld,* M. D. F. R. S. and Member of the Royal Academy of Sciences at
Paris; in a Letter to Tho. Slack, M. D. N° 437, p. 54.

Mr. H. omits giving the history of the fistula lacrymalis, of the different
species of the distemper, or the various methods of treating it, as things suffi-
ciently known; and only remarks that the intention in destroying theos unguis,
and saccus lacrymalis, through which the tears naturally distil into the nose, is
to procure them a new passage thither, by the hole thus artificially made. In
order to keep the sides of this hole asunder, to prevent its filling up, and render
the flesh, which forms its circumference, hard, and as it were callous, a tent
made of prepared sponge, &c. is put into this new passage, where it is con-
tinued a month or two. Notwithstanding this precaution, it happens but too
often, that the tears, instead of keeping the road prepared for them with such
care, flow over the lower eye-lid, as before the operation, and occasion a weep-
ing, which is now become past remedy.

It is easy to prove, that those very means, which are used after the operation
to make the tears distil into the nose, are generally the cause of the subsequent

• M. Hunauld succeeded M. du Verney in the anatomical professorship at Paris. He wrote a
treatise on the bones of the cranium, besides various papers inserted in. the Memoirs of the French
Academy of Sciences. He was possessed of a good collection of anatomical preparations, which was
purchased by the academy after his death. This happened in 1742, when he was in his 41st year.
His fort lay in osteology and the diseases of the bones.



weeping; for by filling the wound with small pledgets, and putting a tent into
the hole, the orifice of the little common canal, that serves to convey the tears
into the lacrymal duct, sufl^ers a compressure, and is rendered hard, thick
and callous; by which, as its diameter is very small, it is easily stopped up.
The contusion made on this small orifice, and round about it, brings on a
suppuration ; after which the parts coalesce, and the orifice of this small canal
closes up. The pus or sanies, which in the course of the distemper flowed
back, both through the common canal, and the small canals, which are a con-
tinuation of the puncta lacrymalia, has sometimes occasioned excoriations; in
consequence of which there happens a regeneration of flesh during the dress-
ings, a small matter of which is sufficient to stop up such slender ducts. Indeed
those small canals, through which nothing passes for a month or two, that the
dressings last, either close by their own elasticity, or their diameters are lessened
by their small vessels becoming varicose. It is true, that injections are some-
times made through the puncta lacrymalia; but the propelling force of these
injections overcomes those resistances, which the cause that naturally drives the
tears into the puncta lacrymalia, is not in a condition to overcome.

Thus it appears, from the detail of the accidents here enumerated, and which
generally happen more or less, that while the artist is endeavouring to preserve
a clear passage for the tears into the nose, he labours, without designing it, to
stop the entry of the upper part of their canal. Mr. H. hopes to make appear,
that the best way to avoid part of these accidents, and keep open the new canal
from the eye to the nose, is precisely to do nothing. This is what experience
has confirmed, and what theory too, well understood, will give us a clear con-
ception of.

It is not very easy to determine, how the tears, and the liquid that is conti-
nually found on the surface of the eye, to preserve the cleanness and transpa-
rency of the cornea, can pass through the puncta lacrymalia. It is also ob-
served, that when we lie in bed, this liquid enters into those puncta lacrymalia,
which in that position are higher than the eye, as well as into the puncta lacry-
malia of the opposite eye. The ascent of liquors in capillary tubes above the
level, might be proposed to explain this last fact. We might also in certain
circumstances conceive the road which the tears keep, to pass from the eye into
the nose, to be a syphon, the short leg of which is divided into two. It is
strange that these two ideas, which strike by their simplicity, have never been
oflTered by any one. It must be allowed however that they are not entirely
sufficient to account for the phenomenon under consideration. The following
rationale seems quite as simple, and more accurate.

The air present at the orifices of all the ducts, which have any communica-


tion with the trachea, is by its proper weight deteraiined to enter them, when
the resistance happens to be diminished. Thus as, during inspiration, it passes
through the mouth and nostrils, so it Hkewise enters the puncta lacrymalia;
and must necessarily carry with il, towards these puncta and their small canals,
the moisture that lubricates the surface of the ball of the eye, as it mixes with
it. Therefore it is easy to perceive already, that to preserve to the tears their
new and artificial road into the nose, we need only commit the whole care to
the continual passage of the air and tears. It is well known in good surgery,
that it is very difficult, not to say impossible, to effect a reunion in a part, that
serves as an emunctory to a liquor constantly flowing to it.

Now let us exan)ine, if nature alone can stop the hole made by the operation.
It will not be imagined, that from the remains of a bony lamina, so thin as the
OS unguis, a sufficient quantity of ossifying juice can work out to stop it up.
The periosteum and saccus lacrymalis are too much lacerated, to think it possible
for them to repair of themselves what they had lost. Nor will it be believed,
that the membrana pituitaria can easily fill up the hole made in it. Those are
the parts concerned in the operation : but even if they are granted to be more
disposed to a re-production than they really are, still the air and tears will
always be able to preserve themselves a passage into the nose.

Therefore, after having destroyed the saccus lacrymalis and os unguis, in-
stead of introducing an extraneous body capable of making the orifice of the
small common canal into the ductus lacrymalis become callous, and of drawing
on a suppuration, the communication between the nose and eye must be left
entirely disengaged, and liberty by this means be given to respiration, to make
both the air alone, and the air mixed with the tears, to pass continually
through it.

Also, the action of these fluids may be assisted by the application of col-
lyriums, and by making frequent injections into the puncta lacrymalia ; which
besides the common effects that may be naturally expected from them, will con-
tribute to prevent the juice, that re-unites the wound made in the skin, from
over-straitening the canal.

On the Cause of the General Trade- Winds. By Geo. Hudley, Esq. F. R. S.

N° 437, p. 38.

Probably the causes of the general trade-winds have not been fully explained
by any who have written on that subject, for want of more particularly and
distinctly considering the share the diurnal motion of the earth has in their pro-
duction. For though this has been mentioned by some among the causes of
those winds, yet they have not showed how it contributes to their production ;

D2 ''■•■^'"' ' '■ ■■'■


or else have applied it to the explication of these phaenomena, on insufBcient

That the action of the sun is the original cause of these winds, it seems all
are agreed ; and that it does it by causing a greater rarefactio-i of the air in
those parts on which its rays, falling nearly perpendicular, produce a greater
degree of heat there, than in other places ; by which means the air becoming
specifically lighter than the rest round about, the cooler air will, by its greater
density and gravity, remove it out of its place, and make it rise upwards. But
it seems that this rarefaction will have no other effect, than to cause the air to
rush in from all parts, into the place where it is most rarefied, especially from
the north and south, where the air is coolest, and not more from the east than
the west, as is commonly supposed. So that, setting aside the diurnal motion
of the earth, the tendency of the air would be from every side towards that
part where the sun's action is most intense at the time, and so a n. w. wind be
produced in the morning, and a n. e. in the afternoon, by turns, on this side
of the parallel of the sun's declination, and a s. w. and s. e. on the other side.

That the perpetual motion of the air towards the west, cannot be derived
merely from the action of the sun upon it, appears more evidently from this :
if the earth be supposed at rest, that motion of the air will be communicated to
the superficial parts, and by little and little produce a revolution of the whole
the same way, except there be the same quantity of motion given the air in a
contrary direction in other parts at the same time ; which is hard to suppose.
But if the globe of the earth had before a rotation towards the east, this by the
same means must be continually retarded: and if this motion of the air be sup-
posed to arise from any action of its parts on each other, the consequence will
be the same. For this reason it seems necessary to show how these phaenomena
of the trade-winds may be caused, without producing any real general mo-
tion of the air westwards. This will readily be done by taking in the considera-
tion of the diurnal motion of the earth: for, let us suppose the air in every part
to keep an equal pace with the earth in its diurnal motion ; in which case there
will be no relative motion of the surface of the earth and air, and consequently
no wind : then by the action of the sun on the parts about the equator, and the
rarefaction of the air thence proceeding, let the air be drawn down thither from
the N. and s. parts. The parallels continually enlarge, as they approach to the
equator, and the equator exceeds the tropics, nearly in the ratio of 1000 to
gi7 ; consequently their difference in circuit is about 2083 miles, and the sur-
face of the earth at the equator moves so much faster than the surfiice of the
earth with its air at the tropics. From which it follows, that the air, as it
moves from the tropics towards the equator, having a less velocity than the
parts of the earth it arrives at, will have a relative motion contrary to that of


the diurnal motion of the earth in those parts; which being combined with the
motion towards the equator, a n. e. wind will be produced on this side of the
equator, and a s. e. on the other side. These, as the air comes nearer the
equator, will become stronger, and more and more easterly, and be due east at
the equator itself, according to experience, by reason of the concourse of both
currents from the n. and s. where its velocity will be at the rate of 2083 miles
in the space of one rotation of the earth or natural day, and above 1 mile and -^
in a minute of time ; which is greater than the velocity of the wind is sup-
posed to be in the greatest storm, which according to Dr. Derham's observa-
tions, is not above 1 mile in a minute. But it is to be considered, that before
the air from the tropics can arrive at the equator, it must have gained some
motion eastward from the surface of the earth or sea ; by which its relative mo-
tion will be diminished ; and in several successive circulations, may be supposed
to be reduced to the strength it is found to be of.

Thus it appears the n. e. winds on this side of the equator, and the s. e. on
the other side, are fully accounted for. The same principle as necessarily ex
tends to the production of the west trade-winds without the tropics ; the air
rarefied by the heat of the sun, about the equatorial parts, being removed, to
make room for the air from the cooler parts, must rise upwards from the earth ;
and as it is a fluid, it will then spread itself abroad over the other air, and so its

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 4 of 85)