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is a dissertation on the seed of the male fern, with a very curious cut, repre-
senting the seed-vessels, their mechanism, and the seed, as viewed by a good
microscope.

The author claims to himself the first discovery of fern-seed, in his disserta-
tion, at the beginning: " You rightly judge," says he to his friend, " me to
have been the first," &c. Boerhaave says, that he showed them to the botanic
professor at Leyden Anno 1673, and that he had drawn the figures of them.
But Dr. William Cole sent an account of the seeds of divers of the plants
called dorsiferous, to * Dr. Robert Hook, in a letter dated September 30, l66g,

* Who was the first Englishman that discovered the seed of the fern by the help of a micro-
scope. — Grig. -'.^ '•-
VOL. VIII. 3 T



506 PHILOSOPHICAL TRANSACTIONS. [aNNO 174).

and gives a pretty just description of the seed-vessels, and the manner in which
they grow, and intended a delineation of the figures. Swaminerdam perhaps
spoke what he thought to be true; and possibly he might have made the disco-
very many years before the time when he showed the seeds to the professor.
However, I am humbly confident of this, after numberless trials made with all
kinds of microscopes, and in all positions, and with different lights, that Swam-
merdam's account is just and accurate, in every point. I have viewed the se-
veral kinds of fern, English maidenhair, other sorts of maidenhair, wall- rue,
harts-tongue, and find the seed-vessels of the same form in all, some little dif-
ference being between some of them in the size only; and in the manner of
their being inserted on the back of the leaf, with the numbers in various plants,
there is a more considerable difference. Where there are fewer seeds, there are
more of a sort of fungus, or tubercle, very like what is called Jews-ears, which
seems to me designed to shelter the seed, which grow, as under covert, round
about them.

In the female fern, and English maidenhair, the whole surface of the leaf on
the inside seems covered: so that the seeds guard each other in some measure;
though in these, after the seed-vessels are shook off, small membranes are found
hereand-there on the surface, a little curled, looking as if they had been raised
with the edge of a sharp pen-knife, from the skin of the leaf, not altogether
unlike the pieces of skin we are wont to raise in trying a pen-knife on one's
hand.

The plant here attempted, as exhibited in %, f), pi. 10, with its seed-vessels,
&c. is the filix mas Dodonaei ; on the inside of the leaves of which are usually
seen several spots placed in a regular manner, of a light-brown or russet-colour.
In this plant the principal part of these spots is the fungus beforementioned,
around which the seed-vessels are inserted.

The seed-vessels consist of a stalk, by which they are inserted into the leaf,
as cc, fig. 7, of a springy ribbed chord ee, having a great number of annular
ribs, exactly resembling the annular cartilages in the aspera arteria; and I know
nothing in nature so aptly resembling this chord, as the aspera arteria of a
small bird, as a robin or nightingale, &c. This chord incircles the globular
membraneous pod, where the seed lies, adhering to it, and dividing it into
two hemispheres. The pod ff is, in appearance, composed of a fine whitish
membrane, somewhat like that which lines the inside of a pea-shell. . The seeds,
fig. 8, k, are irregular in shape, and in their surface a little resembling a sort
of net- work.

In viewing this admirable production of divine wisdom in this plant, I use a
single lens, and no deep magnifier, that I may have the advantage of the light



VOL. XLI.J PHILOSOPHICAL TRANSACTIONS. 507

falling on the objects. I throw a quantity of seed-vessels on a circular plate of
ivory; and, if the plant be newly gathered, the proper time being about the
beginning of September, I often have the pleasure of seeing the seed-vessels
burst; the motion of which at that time may be seen by a good eye unassisted.
But, when I happened to light of a pod not thoroughly crisp, I have had the
satisfaction of seeing the gradual procedure of the bursting of the vessel, in order
to the scattering the seed, in the following manner: first, the chord breaks,
and by expanding rends the folliculum or pod in two parts; by going on to ex-
pand itself, as it departs from a curve, and approaches to a right line, it gra-
dually rends itself away from the globular pod, till it be wholly discharged from
it; when, as there can be no further resistance made to the chord in expanding
itself, it naturally gives a sudden jerk, which in this case is very gentle; and
thus the seeds are shed on the surface of the plate, in the same maimer as if
you were to cast some grains of corn out of a bowl on the plane of a table-
board: this I have several times seen with unspeakable pleasure; but where the
vessel is more crisp, its motion in bursting wholly escapes the sight, flying away
with great violence beyond the field which the lens takes in. Sometimes I have
observed the pod to be 10, sometimes 20 minutes in bursting; in which time
you may have a distinct view of the procedure. I have more than once seen
the pod broke in the side by some accident, as at 1 ; and the seed lodged within,
while the chord has been whole, and still embraced it.

We might have the opportunity of seeing this curious piece of divine mecha-
nism to greater advantage, if we could find a way to get the seed-vessels from

the leaves in a less rude manner than by rubbing them ; for they will not easily \

be discharged from the leaves, for I believe they continue a month after the
seeds are dispersed, so as to collect any number of them together, and this me-
thod bursts them. When I have been attempting this, they fly about like ex-
ceedingly fine vapour or smoke, and are very troublesome to the hands, &c. by
getting into the pores like cowidge. , ^

In fig. 10 is a representation of a small piece of the leaf of harts-tongue
magnified, taken from Dr. Grew's Anatomy, or History of Plants, pi. 72, re-
ferred to book 4, p. 200. I was surprised to see that cut so little resembling
the true figure; indeed the Doctor says it was a cloudy day when he viewed the
object; and I am sure he had no just notion at all of the spring which em-
braces the pod, as to its texture: for it is by no means spiral, or like a screw,
nor do the seeds grow in that regular manner, as represented in the figure.

Whatever use may otherwise be made of this discovery, a moral one naturally
presents itself to us; viz. to admire the infinite wisdom and skill of the won-
derful Creator; for what thinking mind can help being struck with astonish-

3t2 ^



508 PHILOSOPHICAL TRANSACTIONS. [anNO 174}.

mentj when he considers the seed vessels of a coarse plant so minute as to fly
about in the air like vapour, but a little remove from being invisible to a naked
eye, framed with such curious mechanism, containing a great number of seeds,
too fine to be seen by the acutest sight without the help of glasses.

In pi. JO, fig. 9 represents a branch of the plant; fig. 7 the seed-vessels;
fig. 8 the seeds; <xa a branch of the male fern; j3|3 refer to the leaves, on the
backside of which, the excrescencies, like Jews-ears, grow, around which
grow the seed-vessels; cc the stalks of the seed-vessels; da shoot from the
stalk, producing sometimes another seed-vessel on the same stalk; ee the
springy chord, embracing the pod, which contains the seed; ff the pod; g the
pod with a crack or chink in it, to represent its being about to be divided into
two hemispheres; hh the chord expanded, approaching to a right line; ii the
two hemispheres, when the pod is divided in two ; k the seeds ; 1 seeds in the
pod, the membrane being broken and turned up.

uln extraordinary Case of the Heart of a Child turned upside down. By Jos.
Ignat. de Torres, M.D. of Gandia in Valentia. N°46l, p. n^.

The following is a new and surprising prodigy, concerning the heart, the
Uke of which was never hitherto observed, till Dr. T. saw it on the 29th of
December J 736, in a new-born female infant, of the town of Almoyna. Innu-
merable phenomena have been observed in the human heart, some few of which
he here mentions.

Balloni saw a heart so large, that its monstrous size alone, without any defect
y in the lungs, occasioned an asthma. Bartholin found caruncles in the ven-

tricles. Spilemberger observed a small bone in one, which occasioned a phthisis.

Zacutus Lusitanus relates, from the report of another person, that a * worm
was found in the left ventricle, which brought on dreadful symptoms. Its head
was yellow, its body white, and its tail split. Riolan opened the body of a man,
whose heart was cartilaginous. According to Rayger, the aorta with the valves
was found ossified; which was the cause of sudden death, Genesius of Va-
lentia, a very able physician, has apprised me in one of his letters, that on
opening his young son, he found the heart inverted; that is, the left ventricle
on the right, and the right on the left side. Amorosius saw a heart with 2
points, which on the outside showed the 2 ventricles. Sirenarius found a heart
with its cone in the right side, and there the pulsation was constantly felt,
Martinezius, first physician to the king of Spain, observed in a new-born male
infant, the heart pushed out of the breast, with its cone and basis lying hori-

* Rather a polypus. C. M.— Orig.



VOL. XLI.J PHILOSOPHICAL TRANSACTIONS, SOQ

zontal, and without a pericardium ; a new and remarkable phenomenon ; as if
the heart, not bearing so close a confinement, burst through the breast, and,
having broke the sternum, appeared on the outside.

Dr. T. omits Benivenus, Muretus, Scultetus, and Giersdorf, who observed
the heart hairy, and found stones, polypuses and abscesses in its ventricles.*

He then states that he had observed, in a new-born female infant, the heart
without a pericardium, and turned upside down, so that its basis, with all the
vessels, had fallen down as low as the navel; and its apex, still on the left side,
lay hid between the 2 lungs. It is amazing how the circulation could be car-
ried on, the heart being thus inverted; and yet the child lived several days after
birth. He observed the heart from its basis, whence the aorta and pulmonary
artery spring, and where the cava and pulmonary vein enter it, to its cone,
surround loosely with several windings of these vessels, through which the
blood's circulation must necessarily be performed.

Of the Curve called, from its Form, a Cardioide. By M. John Castillion, of
Montagny, Prof. Philos. in the Acad, of Lausanne, and F. R. S. N" 461,
p. 778. From the Latin.

The diameter ab of the semicircle amb, fig. J, pi. 11, touching the circum-
ference in the point b, so as always to pass through the point a, will generate
this curve.

From this genesis of the curve, it appears, 1. That DAa, perpendicular to
ab, is equal to double the diameter.

1. That the periphery of this curve ADNnaNA terminates in a.

Now through a and a draw ge and Aa perpendicular to ca, and en any where
perpendicular to an. Then, from the genesis, it follows that an = ba + am;
and, by the similar triangles uan and mba, Aa ^ bm + mp, and nq =.

ma + AP.

This is the chief property of the curve. There is also another pretty pro-
perty, that the line nn is always equal to double the diameter, and is always
bisected by the circle in m.

Now put BA = a, aE = X, en =: y; then will qn = "^ y + 2a, and an =:
'Z x^ -\- y^ — 4ay + Aa^, and ma = + a + Var'^ -\- y^ — Aay -\- 4a^; which 4
lines being compared by analogy give this equation of the curve,
4 « 3 + "i^y — 6ax-y + x* ? „

Hence the subtangent of the curve is easily found by the common fluxionary
method. But an easier way of drawing the tangent may be deduced from the
generation of the curve. Let man come into the nearest place to the first



510 PHILOSOPHICAL TRANSACTIONS, [aNNO ]741.

rnxn; then take ar = am, and xr = an, and joining mr, Nr, draw at parallel
to them, and m, m, and n, n, being joined, draw mt, nt. Now nx : At :: nr or
tiiR : rN :: mR X ma : tn X am :: otr X ma : mr X an :: ma X Am : an x at; but
in the ultimate ratio uiA = ma, and ta is perpendicular to mn, therefore «a : At
:: MA*: AN X at; now if, through the centre of the circle f, there be drawn
the line mf, produced to meet ta, also produced in g, that is to the circum-
ference of the circle, then will ma^ = ta X ag; therefore tia : At :: 4g : an ;
therefore describe a semicircle through g and n, which will cut the line at in t,
from which /n being drawn, it will be a tangent to the curve, to which also no
is perpendicular; hence mo being joined, a parallel to it, drawn through n, will
be the tangent to the curve.

And here it may be observed, that this method of drawing tangents agrees
with most curves. Thus let ab, fig. 2, be the conchoid of Nicomedes ; then,
supposing the former preparation, bp : Ft :: br or cr : e.b :: cr X cp : r^ X cp or
re X PH :: cp* : tp X PR ; hence the former construction is derived.

Again, let a line cpb, fig. 3, of a given length, have its extremity c moved
along the line cdt, perpendicular to da, and always pass through the point p
in the same given line da, and so generate a curve ab. Now applying the
former preparation and reasoning to this, then we shall have bp : Ptiiba or
re : eb : cr X CP : rb X cp or bp X re :: cp* : bp X pt, as before.

Also the method de maximis and minimis gives the greatest ordinate = \a,
and its absciss = ^av'3. In like manner the greatest absciss might be investi-
gated, but by a tedious process ; therefore find it thus : because en, fig. 1 , is
a tangent to the curve, the line mg, drawn from the point m through the centre
F, determines the point g, from which gn being drawn perpendicular to en,
therefore also to Aa by the hypothesis. But ng = av = ma + ap ; therefore
vp = MA ; but ba : am :: ma : ap ; therefore ba : pv :: vp : pa ; but pp = fv :=
a — 2z ; therefore a : a — 2z :: a — 2z : z. Hence is easily deduced z = -^a ;
EN=:4a; Aa = ^\/3. Where it is to be noted, that the same point m,
which gives, in the line namn, the point of the greater ordinate, gives also
the point of the greater absciss.

^ Machine to represent Eclipses of the Sun. By J. u4nd. Segner, Med. Physic,
et Mathem. Prof. Goetting, R.S.S. N" 46 1, p. 781. From the Latin.

A projection of the arches and circles of the earth's illuminated surface, on
a plane, may serve well enough to show any solar eclipse ; and if the places on
the earth's surface, as cities, islands, &c. be inserted in the projection, and a
circle be added, to express the position and magnitude of the lunar penumbra.



VOL. XLI.J PHILOSOPHICAL TRANSACTIONS, 511

and some smaller circles concentric with it ; we have then in one view those
places where the sun is hid by the moon, or any part of it concealed from our
sight.

But such an image is momentary ; and though it shows well enough what
happens at any precise moment of time, as for instance when the centre of the
lunar penumbra first enters the earth's disk, yet it cannot exhibit the other
phenomena, which depend partly on the earth's rotation, and partly on the
moon's motion.

While the earth turns round, the circles of latitude indeed, and consequently
their projection, remain the same ; but the meridians, or circles of longitude,
are continually changed, and consequently their projection, and the situation
of places on the earth, as far as depends on them.

But the artificial globe of the earth shows the illuminated hemisphere at any
point of time, with very little trouble. For the pole being elevated above the
horizon, or depressed below it, so that the elevation or depression may be equal
to the sun's declination at that given time ; or, which comes to the same thing,
the sun's place in the ecliptic of the globe being brought to the zenith, the
artificial -horizon becomes the boundary of light and shade ; and nothing re-
mains, to exhibit plainly the illuminated hemisphere, but to turn the globe on
its axis, till it obtains the position adapted to the hour of the day.

Thus, what is very difficult in projections, is easily performed by the globe,
and also more conformably to nature. Considering this, it occurred that we
still wanted, for representing all the phenomena of a solar eclipse, to project
the lunar penumbra on the globe, and to make an instrument to represent its
situation at any time, and to refer it to those places on the earth which are
marked on the globe. Hence Mr. Segner devised such an instrument, which
is as follows.

Fig. 4, pi. 11, represents a common terrestrial globe, furnished with its
horizon, meridian, and hour circle. To the horizon are connected 2 wooden
arms, ab, ab, of a length a little exceeding the semidiameter of the globe ; and
one end of each arm is made to clasp the horizon, to any part of which it may
be fastened by screws, a§ shown at d.

On the opposite extremities, b, b, are wooden columns, be, be, erected per-
pendicular to the horizon, of the height of the semidiameter of the globe, and
of the breadth of the brazen meridian ; so that a right line being drawn through
the tops of the columns, cannot touch the meridian.

On the top of each column is a small brazen ball, each perforated by an iron
axis, projecting on both sides, and firmly joined to the ball, the lower parts of



512 PHILOSOPHICAL TRANSACTIONS. [aNNO 1741,

the axes being fixed into the columns, so that the balls are held fast in a posi-
tion parallel to the horizon of the globe.

The upper parts of the axes are round and polished, as well as the upper sur-
faces of the balls ; and they receive round plates of brass, efg, efg, resting on
the balls in such a manner, that, being turned on the axes, they always remain
parallel to the plane of the horizon. The plates are about 3 inches diameter,
and have each a notch in the circumference, to receive a thread, but the plate
efg a little less than the other plate efg ; and this latter has a circle inscribed
on it, divided into degrees, with an index h, to point to any part.

There are 3 brazen rays, ik, il, im, connected at i, containmg equal angles,
kil, lim, mik ; the place i being perforated with a very small hole. The rays
are elastic, and very thin, and in length nearly equal to a 4th part of the dia-
meter of the globe. They have also small perforations at 1 and m, through
which a thread being drawn, is brought round the plates in the direction
mEFGgfel, the ends being fastened together between 1 and m : therefore the
skeleton of the penumbra is also rendered immoveable at the part of the thread
elmE. Hence the skeleton is turned either way, in a right line, by turning the
plate EFG or efg.

The following circumstances must be changed according to each particular
eclipse. The chief of these is the disk of the penumbra With regard to this,
having found, by the tables of the eclipse to be represented, the semidiameter
of the lunar penumbra on the earth's disk, as also the moon's horizontal paral-
lax, it is, as the moon's horizontal parallax, is to the radius of the disk of the
penumbra, so is the semidiameter of the terrestrial globe used, to the quadrant,
which expressed the radius of the penumbra by the magnitude of the globe.
' To set every thing in order for any moment of a given eclipse, we must pro-
ceed in the following manner. Having found by calculation the points of the
bounds of light and shade, by which the moon's centre first enters the earth's
disk, and departs from it again, they are to be marked on the horizon of the
globe, and the arms ab, ab, are to be placed so, that the plate efg being turned
round, the centre i of the disk of the penumbra klm, may pass over them ;
which when done, will be shown by the pendulum in. Then find the time
when the centre of the penumbra is in any remarkable place, as when it first
enters the earth's disk, and place the globe, by means of the meridian and
equator, in such a manner, that the part above the horizon may show the
earth's hemisphere, at that time illuminated by the sun. Then turn the plate
EFG till the centre of the penumbra, i, is over that particular place. This
done, move the index h of the plate to the beginning of the division. Thus



VOL. XLI.] PHILOSOPHICAL TRANSACTIONS. 513

every thing is rectified for that time, and its phenomena may be col-
lected.

Now the horary motion of the moon from the sun being taken from the
tables, it will be, as the moon's horizontal parallax, is to her horary motion,
so is the number of the parts of the plate efg, which answer to the semidi-
ameter of the globe, above found, to the quadrant which shows how many
parts, on turning the plate round, are to be drawn through the place of the
index, to have the situation of the disk of the penumbra, an hour before or
after the time which answers to the primary situation. The disk therefore
being brought to this place, and the globe turned on the axis, the phenomena
of this time may be had in like manner.

The places marked on the surface of the globe, lying perpendicularly under
the disk of the penumbra, in any situation of it, may be found by the pendu-
lum. But they are seen at one view, when the whole apparatus is exposed to
the sun's rays reflected from a plain speculum, in such a manner, that the rays
may fall perpendicularly on the horizon of the globe. For then such shadows
will be projected from the disk of the penumbra, on the globe, as are like the
penumbrae cast on the earth by the moon, by which may be seen the phases of
the eclipse for any place.

But this motion of the sun is inconvenient. Perhaps those who have a large
burning-glass will make use of a lamp, the rays of which may be thrown on the
globe from the glass, in a position perpendicular to its horizon. Otherwise,
by viewing the globe from a distance through a perspective glass, then the
disk klm, being brought on the surface of the globe, exhibits the penumbra.
Various other contrivances may also be devised, for exhibiting the several phases
of the eclipses.

Samuelis Christiani Hollmanni, Logic, et Metaph. in nova Gottingensi Academia
P. P.O. Observatio de Sceletorum, ex Foliis virentibus paratorum, quorum-
cunque Duplicatura. N°46l, p. 789.

Samuelis Christiani Hollmanni, Logic, et Metaph. in nova Gottingensi Academia
P. P. 0. de Duplicaturee Fibrarum, in Foliis quibuscunque conspicuce Usu,
aliisque hue pertinentibus. Conjectures. N°46l, p. 79^.

The observations of Mr. Hollman add nothing of importance to the disco-
veries in vegetable anatomy and physiology made by Grew, Malpighi, and
others, detailed in the preceding vols, of these Transactions.

VOL. VIII. 3 U



5)4 PHILOSOPHICAL TKANSACTIONS. [aNNO I 74 1 .

An Earthquake at Scarborough, Dec. 1Q, 1737, communicated by Maurice
Johnson, Esq. N° 46l, p, 804.

The ends of several inclosures or fields behind the clifF, on the back of the
spa, sunk down very low into the ground, making a large valley of a vast
length, and considerable breadth, with 5 cows then grazing on it, the weight
of which shook and opened the hill behind the house, after a frightful manner,
and forced up the sands 1 00 yards in length on each side the space, and 27
broad, to the height of 6 yards, and in some places 10 yards high.

The pier, entire as it was, moved sideways out of its place, and rose up
about 5 yards in the air ; the house fell down, and at the same time took fire.
The flag-house, and wooden rails, which were about the mouth of the well,
were forced up in the air above 10 yards high, so that it is thought the spa-
water is entirely lost for ever.*

No persons were hurt, the people of the house getting away in time.

An Examination oj" Sea-water frozen and melted again, to try what Quantity of
Salt is contained in such Ice, made in Hudson s Straits by Capt. Christopher
Middleton, F. R. S. N° 4dl, p. 806.

Dr. Hales, in his learned paper lately read at the Royal Society, where he
proposes a method of rendering sea-water fresh, and wholesome to drink, men-
tions a diversity of saltness of the water at the Nore in the mouth of the
Thames, and the water taken up in the Mediterranean Sea, this containing
-JL- of salt, the former ^. Mr. Boyle, in his Observations on the Saltness of
the Sea, says, that about Holland the salt in the sea-water has been found to
be -^. In the English Channel, he found sea-water Vt heavier than conduit-
water, and, by immersing a lump of sulphur in it, he found the difi^erence W ;
but bv distillation ad siccitatem, he found the salt to be -^, and in another



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 59 of 85)