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patience and resignation, in hopes nature might point out some method for her
relief; and gave her no more medicines, but a soluble electuary to procure her
stools, which she took every night.

After some time, the fetid purulent matter ceased from its discharge in the
urine, but came away through the vagina, after the manner of the whites.
She was quite emaciated by continual pain, and those discharges.

In April 1735, that purulent fetid matter, discharged at the vagina, now
came through the anus ; she complained of a prodigious weight there, and
about the middle of June 1735, she had frequently very bloody stools, and
once a discharge of more than ilb. of fresh blood. On the 2d of July, having
occasion to go to the close-stool, as she sat there hard straining, but to no
purpose, she thought she felt a hard substance ready for expulsion, and sent
to her neighbours, who found a large substance hard and rugged, so much,
that it tore one of the women's fingers, and made it bleed, in the lower part of
the gut rectum, close to the sphincter ani. Mr, Wisdom, the surgeon, was
immediately called, who endeavoured to extract this substance, and broke
some part of it off ; but he was forced to dilate the rectum, and so extract it
that way. It was a hard unequal ragged flinty stone, was 10-^ inches round,
and weighed 8-l oz, after it was extracted. The woman was easy from that



VOL. XLI.] PHILOSOPHICAL TRANSACTIONS. 443

moment ; the wounds, by the care and skill of her surgeons, healed ; and she
recovered perfectly, except a numbness and contraction she had in some of the
fingers of both hands, and both feet and toes.

An Account of M. Leuwenhoek's Microscopes. By Mr. Henry Baker, F. R. S.

N° 458, p. 503.

Martin Folkes, Esq. in N° 380 of these Transactions, gave such an exact
and full description of the structure and uses of these glasses, as left little more
for Mr. B. to offer, than a calculation of their magnifying powers, some re-
flections arising from such calculations, and a brief account of what improve-
ments in microscopes had lately been made.

In order to this, he first viewed attentively the objects applied to these mi-
croscopes by M. Leuwenhoek himself, which Mr. Folkes has given a list of in
his account ; but the greatest part of them were destroyed by time, or struck
off by accident ; which indeed is no wonder, as they were only glued on a pin's
point, and left quite unguarded. Nine or ten of them, however, are still re-
maining ; which, after cleaning the glasses, appeared extremely plain and dis-
tinct, and proved the great skill of M. Leuwenhoek, in adapting his objects
to such magnifiers as would show them best, as well as in the contrivance of
the apertures to his glasses, which, when the object was transparent, he made
exceedingly small, since much light in that case would be prejudicial ; but,
when the object itself was dark, he enlarged the aperture, to give it all possible
advantage of the light. The lens being set so as to be brought close to the eye,
is also of great use, since thereby a larger part of the object may be seen at
one view.

All these microscopes are of one and the same structure, and that the most
simple possible, being only a single lens, with a moveable pin before it, on
which to fix the object, and bring it to the eye at pleasure.

Though it must cost much trouble to measure the focal distances of these lQ
microscopes, and thence ascertain their powers of magnifying, yet without that
it would be impossible to form a right judgment of them, or make any reason-
able comparison between them and others. This task therefore Mr. B. per-
formed, with as much care and exactness as he was able ; and has shown, in the
following table, how many of them have the same focus, and consequently
magnify in the same degree ; how many times they magnify the diameter, and
how many times the superficies of any objects applied to them. The calcula-
tions are given in round numbers, the fractions making but an inconsiderable
difference.

3 l2



444 PHILOSOPHICAL TRANSACTIONS, [aNNO 1740.

A Table of the Focal Distances of M. Leuwenhoek's 26 Microscopes, calculated
by an hich Scale divided into 100 Parts ; with a Computation of their magni-
fying Powers, to an Eye that sees small Objects at 8 Inches, which is the
common Standard.

Microscopes Distance of the Power of magnifying Power of magnifying
with the Focus. the Diameter of an the Superficies,

same focus. Object.

Parts of an Inch, Times, Timet,

1 Vs <"■ TTW 160 25600

1 t4, 133 nearly 17689

1 T^ • • • 11* nearly 12996

3 -^ 100 10000

3 -^ 89 almost 7921 almost.

8 Vis ^^ ^-^^

2 -^ 72 something more. 5184 something more.

3 -^ 66 nearly 4356 nearly.

2 ^ 57 3249

1 -J^ 53 nearly 2809 nearly.

1 ^ 40 1600

IT

This cabinet is only the second in Mr. Leuwenhoek's collection, and is very
far from containing all the microscopes he had, as many wrongly have imagined.
We find here indeed, 26 microscopes in 13 little boxes. Each box contains a
couple of them, and is marked in two places with a number, to distinguish it
from the rest. But as the first of these boxes is marked 1 5, and the rest with
following numbers on to 27 ; it necessarily implies there were 14 preceding
boxes. Mr. Leuwenhoek, then, had another cabinet, that held 14 boxes
before ours in numerical order, and probably each box contained a couple of
microscopes, as our boxes do. But, besides these two cabinets, he had se-
veral other microscopes of different sorts, as appears by his own writings.

Many of Mr. L.'s microscopes must certainly have been much greater mag-
nifiers than any in our possession. And we are assured by himself, in many
places, that such he had.

While looking over these microscopes of M. Leuwenhoek, an opportunity
presented of examining and comparing with them a curious apparatus of silver,
with 6 different magnifiers, belonging to Mr. Folkes, and then newly made for
him by Mr. Cuff, in Fleet-street. The body of this instrument, into which
the glasses are occasionally to be fastened, is after the fashion of Wilson's
pocket microscope, and contrived to screw into the side of a scroll fixed on a



TOL. XLr.] PHILOSOPHICAL TRANSACTIONS. 445

pedestal, from which a turning specuhim reflects the light upwards upon the
object : it is likewise contrived to be used with the apparatus of the solar mi-
croscope. Descriptions and figures of both of which are given in Mr. B's book
intitled, The Microscope made easy. Edit. 2d. Lond. 1743, 8vo.

Mr. B. measured the focal distances, and magnifying powers, of the 6 glasses,
and found them to be as follows :

A Table of the Six Magnifiers belonging to Mr, Folke/s Microscope, calculated
by an Inch Scale divided into a hundred Parts, with a Computation of their
Powers, to an Eye that sees Objects at 8 Inches.

Glasses. Distance of Magnifies the Magnifies the

the Focus. Diameter. Superficies.

1st -^ of an Inch 400 l60,000

2d ^ 160 25,600

3d ^ 100 10,000

4th ^ 44 1,936

5th ^ 26 676

6th i 16 256

The above calculation shows, that Mr. Folkes's first glass magnifies the su -
perficies of an object 6 times as much as the greatest magnifier of M. Leuwen-
hoek. And that the animalcula, a million of which, he says, scarcely equalled
a grain of sand, would, if viewed with this magnifier, appear as large as l6
grains of sand do to the naked eye. And M. Leuwenhoek must have had
glasses to magnify even more than this, though they are not come to us. For
we cannot otherwise conceive, how he could observe the animalcules in the
semen masculinum of a flea, and of a gnat, as we find he did, or assert, as he
does in the strongest terms, that he could see the minutest sort of animalcules
in pepper-water, with his glasses, as plainly as he could swarms of flies or gnats
hovering in the air with his naked eye, though they were more than ten mil-
lions of times less than a gr^in of sand. And lest this should be imagined only
a random guess, he gives immediately a regular arithmetical calculation to
prove his computation right. But we may all be sensible, that no glasses
in this cabinet are able to render such minute objects distinguishable.

One thing alone (which, when slightly considered, may appear but trifling)
has conduced greatly to the modern improvements ; viz. the making use of fine
transparent Muscovy talc or isinglass, placed in sliders, to inclose objects in.
Had M. Leuwenhoek known this way, it would have saved him a vast deal of
expence and trouble. For then, we may reasonably suppose, instead of mak-
ing an entire and separate microscope for every object, he would probably have



446 fHILOSOPHICAL TRANSACTIONS. [aNNO 1740.

secured his objects in sliders, as we at present do, and have contrived some
such means as ours, of screwing his several glasses of different magnifying
powers, occasionally, to one and the same instrument, and of applying his
sliders to which of them he judged best. A few good glasses, gradually mag-
nifying one more than another, would, by such a method, have answered all
the purposes of his great number, and his objects would have been preserved in
a much better manner.

Passing over the different microscopes invented by Wilson, Marshal, Cul-
pepper, Scarlet, and others, though all deserving praise, Mr. B. notices two
extraordinary improvements lately made ; viz. the solar or camera obscura
microscope, and the microscope for opaque objects. But these inventions are
by the ingenious Dr. Liberklmn. Mr. Cuff, in Fleet-street, has taken great
pains to improve and bring these to perfection ; and therefore the apparatus
prepared by him is wiiat are described below.

This solar microscope is composed of a tube, a looking-glass, a convex lens,
and a n)icroscope. The tube is of brass, near 2 inches in diameter, fixed in a
circular collar of mahogany, which, turning round at pleasure, in a square
frame, may be adjusted easily to a hole in the shutter of a window, in such a
manner, that no light can pass into the room but through the tube. Fastened
to the frame by hinges, on the side that goes without the window, is a looking-
glass, which, by means of a jointed brass wire coming through the frame, may
be moved either vertically or horizontally, to throw the sun's rays through the
brass tube into the darkened room. The end of the brass tube without the
shutter has a convex lens, to collect the rays, and bring them to a focus ; and
on the end within the room, Wilson's pocket microscope is screwed, with the
object to be examined applied to it in a slider. The sun's rays being directed by
the looking-glass through the tube upon the object, the image or picture of the
object is thrown distinctly and beautifully on a screen of white paper, and may
be magnified beyond the imagination of those who have not seen it. Mr. B.
assisted lately in making some experiments by means of this instrument, and a
particular apparatus contrived by Dr. Alex, Stuart, for viewing the circulation of
the blood in frogs, mice, &c. and had the pleasure of beholding the veins and
arteries in the mesentery of a frog magnified to near 2 inches diameter, with
the globules of the blood rolling through them as large almost as peppercorns.
They examined also the structure of the muscles of the abdomen, which were
prodigiously magnified, and exhibited a most delightful picture.

The microscope for opaque objects remedies the inconvenience of having the
dark side of an object next the eye ; for by means of a concave speculum of
silver, highly polished, in whose centre a magnifying lens is placed, the object



VOL. XLI.] PHILOSOPHICAL TRANSACTIONS. 44/

is SO strongly illunnnated, that it may be examined with all imaginable ease and
pleasure. A convenient apparatus of this kind, with 4 different specula, and
magnifiers of different powers, has lately been brought to perfection by
Mr. Cuff.

M. Leuwenhoek. says, (in his 2d vol. part ii. p. 93,) that sometimes, to
throw a greater light on his objects, he used a small convex metal speculum ;
and it is highly probable, that our double reflecting microscope may be owing
to this hint. Also, in the 4th volume of his works, p. 182, after describing
his apparatus for viewing eels in glass tubes, M. Leuwenhoek adds, that he
had another instrument, to which he screwed a microscope set in brass ; on
which microscope, he says, he fastened a little dish, that his eye might be
assisted to see objects better ; for he says, he had filed the brass which was
round his microscope, as bright as he could, that the light, while he was view-
ing objects, might be reflected from it as much as possible. This microscope,
with its dish, seems so like our opaque microscope with its silver speculum, that,
after considering his own words, it is probable he may properly be esteemed
the inventor of it.

An Inquiry into the Causes of a dry and wet Summer. Anonymous.

N°458, p. 519,

This writer concludes, that a frosty winter produces a dry summer ; and a
mild winter a wet summer. And he finds, from these and some other observa-
tions, casually made, that the weather depends very much on the wind. He
therefore begins with inquiring what is the cause of winds, and then proceeds
to guess why the wind influences the weather.

Wind is a stream of air ; air an unmixed fluid encompassing our globe, with
a shell of at least 60 miles thick. Every particle of air gravitates equally to-
wards the centre of the earth. Air is capable of being compressed and ex-
panded. The more air is compressed, the heavier it is; the more it is expanded,
the lighter. Cold and heat, whatever they be, or however they act, produce
these contrary effects in the air : that is, cold compresses the air, and heat
expands it ; therefore cold and heat, in different parts of the air, will make it
flow : for cold making the air heavy, and heat making it light, the lighter must
give way to the heavier ; as, in a balance, a greater weight makes a smaller rise.
We daily see a proof of this in a stove.

The sea and land-breezes, and the trade-wind, owe their origin to these
causes. The sea-breeze, when regular, begins at 9 o'clock in the morning,
approaches the shore gently at first ; increases till 12; retains its full strengtii
till 3 ; then gradually decreases till 5, when it dies away. At 6 in the evening



448 PHILOSOPHICAL TRANSACTIONS. [anNO 1740.

the land-breeze begins, and continues till 8 next morning. The interval be-
tween these two breezes, at morning and evening, are the hottest parts of
the day.

The way of accounting for this vicissitude of sea and land-wind, is thus :
the sun, as it ascends, sheds its heat equally on the land and sea ; but the
earth receives the heat sooner than the water, or else reflects it stronger. For
one or both of these reasons, the air that hangs over the land, is heated more
than the sea air, it becomes thereby more rarefied, and consequently lighter :
and therefore the sea air, with its superior weight, flows in upon it every way.
The intervals between are owing to the air of both places being in an equal de-
gree of heat, and consequently of equal weight.

The trade-wind never varies, which is thus accounted for: the air just
under the sun is the hottest : the cold air presses upon the hot, as the
hot air follows the sun ; and therefore it makes a perpetual flow of wind be-
tween the tropics from Africa to America, and from thence to the East-
Indies.

With regard to the wind influencing the weather ; though air be an un-
mixed fluid, yet it is capable of receiving many vapours, which float in it, as
we see other bodies float in water. Sometimes the vapour ascends, and some-
times it falls to the ground. All which is probably effected by heat and cold
in this manner : heat separates water into small particles, and the incorporated
air, rarefied by the same heat, blows up those particles into bubbles ; by which
means the swoln vapour, becoming specifically lighter than a like space of
ambient air, ascends, swift at first, affording a pleasant sight in a warm sum-
mer's day, and then gradually slower, till it gets up to that part of the air
which is of equal lightness with itself; and there it remains, as long as the air
continues in the same state. But whenever the air cools, in which these
watery bladders float, the cold contracts the bladder, which becoming thereby
specifically heavier than the air, down it falls in dew, or rain. A common
alembic sufficiently shows the operation of heat and cold on the ascending and
descending vapour.

Thus in a calm evening, when there is no wind to waft the air, as the heat
of the sun declines, the cold arrests some few of the last ascending vapours,
and, by its own force, without any other change in the state of the air, com-
pels them to return, in dew, to the very spot from whence they arose; whilst
their brethren escape, who go out of the reach of the cold a little before the
approach of night.

Since therefore the same air, in different states of heat and cold, affects
vapour in this manner, it thence follows, that vapour, wafted from air of one



VOL. XLI.j PHILOSOPHICAL TRANSACTIONS. 449

temperament to another, must be affected in the same manner also : so that
vapour, carried from a colder to a warmer air, will ascend ; and, on the con-
trary, vapour carried from a warmer to a colder air, will descend.

Now if cold condenses the air, and thereby makes it press on the warmer ;
and if vapour, carried by a stream of air from a colder to a warmer region,
ascends; we have the reason why the north-east blows, and why it blows dry. '

Let us fix upon some spot in the continent of North-Europe, whence this
wind comes to us : suppose Archangel, which lies on our north-east point, and
is in 65 degrees northern latitude: when the frost is intense, the incumbent
air there must needs be very heavy ; that air will press every way : qua data
porta, ruit. Let us consider which way this condensed air can burst out from
thence : it cannot go to the north, where the cold is greater ; nor to the east,
for the air over the large continent of Tartary is at least of equal coldness with
itself. To the west, the air might find a free passage over the ocean, were not
the colds of North-America too near. The main outlet is between both, to-
wards the Atlantic-Ocean : the warm air over which being able, of itself, to
make but a feeble resistance, yields to the superior force; the conqueror eagerly
pursues his victory, and we, happening to lie directly in the way, feel then a
cold dry north-east wind : this is the wind that brings us frost in the winter.
When the winter is severe, it continues to blow all the spring, and its influence
reaches to the end of the summer.

This it seems sufficiently proves, that air, flowing from a cold to a warmer
quarter, will blow dry : but, like a willing witness, it proves too much ; for, if
wind proceeds only from cold air pressing on hot, and if heat makes the vapour
ascend, it follows from thence, that wind can never bring rain ; whereas we
find the contrary by sad experience.

How can this be accounted for, on the principles commonly received ? That
vapour, wafted from a warmer to a colder region of air, should precipitate, is
what we have already shown. But the question is, why does the south-west
blow ? What is the cause why a stream of air should be carried, for so long a
time, and with so great violence, as we have often felt, from a warmer to a
colder, from a rarer to a denser, from a lighter to a heavier quarter ? To the
north-east of us lies the continent of North-Europe, great part of which is, in
the winter, deprived of the sun's heat, and consequently very cold ; on the
other side, to the south-west, lies the vast Atlantic ocean. We find by ex-
perience, that the sea-shore is warmer than the inland ; that the sea is warmer
than the shore; and that the ocean is still warmer than the sea. Besides, the
more you go from hence towards the south, the nearer you go to the sun ; and
the more north, the farther from it : this must make the south-western ocean

VOL. VIII. 3 M



450 PHILOSOPHICAL TRANSACTIONS. [aNNO 1740.

much warmer than the continent, that hes at an equal distance, on the opposite
point : from this very warm place, the wind blows to a place much colder ; and
yet there must be a natural cause of all this apparent contradiction to the laws
of nature.

It will be in vain to seek for the cause of the wind in this ocean itself, or in
the air over it, influenced only by the sun, and the surface of the sea. But
there may be tornados in those seas : our seamen often meet them between the
tropics, seldom in the ocean to the north of the northern tropic. But were
they more frequent and violent than they really are, yet they are not last-
ing, and therefore cannot produce a long steady course of south-west winds
with us.

Probably our south-west wind is no other than an eddy of the trade-wind, re-
flected from America to us. There are also some other facts which strongly
support this hypothesis ; viz. currents of the sea, and the wind in the Atlantic
ocean, to the northward of the trade-wind.

With regard to the currents, Dampier tells us, it is generally observed by
seamen, that, in all places where the trade-wind blows, the current moves the
same way with the wind ; and that though it be perceived most near the shore,
yet it makes no sensible rising in the water, as the tides do. He says, there is
always a strong current setting from Cape St. Augustin westward, occasioned,
as he remarks, by the south-east trade-wind driving the surface slanting on the
coast of Brasil ; which, being there stopped by the land, bends its course
northerly, towards Cape St. Augustin ; and, after it has doubled that promon-
tory, it falls away towards the West-Indies, down along the coast westward, till
it comes to Cape Gratia de Dios ; from thence north-west towards Cape Catoch
in Jucatan, thence to the northward between Jucatan and Cuba. He says, that
in the channel, between Jucatan and Cuba, he has found the currents extraor-
dinarily strong ; that it is probable, that the current which sets to leeward, on
all the coast from Cape St. Augustin to Cape Catoch, never enters the bay of
Mexico, but bends still to the northward, till it is checked by the Florida shore;
and then it wheels about to the east, till it comes near the gulph's mouth, and
passes with great strength through the gulph of Florida, which is the most re-
markable gulph in the world for its currents, because it always sets very strong
to the north.

Let us then suppose the wind, which drives this water before it, to follow it
much in the same course ; and that, instead of striking against one plain sur-
face, with such an inclination as would dn-ect it to us, it strikes against a mil-
lion, yet still bending this way : let this natural supposition be admitted, and
we have the very thing sought for, viz. a proper direction.



VOL. XLI.] PHILOSOPHICAL TRANSACTIONS. 451

The other fact is this : that when our ships return from the West Indies
through the gulph of Florida, and are got into the wide ocean, they have a re-
gular wind at south-west, or near that point, which sometimes attends them to
their very port. This wind cannot have its rise in that ocean, nor cm it come
from any continent that lies to the north, or even west of it ; therefore pro-
bably it must be an eddy of the trade-wind.

From America to the west of England this wind glides over the ocean, a
plain field, that gives no opposition, and which, with its natural warmth,
encourages the waft, by making the air over it more ready to yield to the im-
pelled force. Having thus opened a passage for the trade-wind to flow even to
us, with a back stream; and admitting this conjecture to be right, we have the
cause why the south-west wind blows with us ; and then there can be no great
difficulty in finding out the reason why it brings so much rain. For this wind
blowing over a warm ocean, which sends up many vapours, by the time it
reaches us, it comes charged with an infinite mass of watery bladders, which
the cold of this climate condenses, and then they descend in showers of rain.

Notahilia qucedam in Itinere Alpino-Tyrolensi observata per Baltkasarem
Ehrhartum,* M. D. Memingensem in Epistola ad C. Mortimerum, R. S.
Seer, missa. N° 458, p. 547-

This paper contains some observations (not interesting in the present ad-
vanced state of geology) relative to the structure and formation of the Tyrolese
Alps, together with an enumeration of the plants found growing on that chain
of mountains.



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 52 of 85)