[Sidenote: _It seems these were _Easterly_ winds._]
8. Generally also it falls in great winds; and somewhat it seem'd to sink,
when I open'd a wide door to it, to let in stormy winds; yet I have found
it to continue very high, in a long stormy wind of 3. or 4. daies.
9. Again, generally it is higher in an _East_ and _North_-wind. (_Caeteris
paribus_) than in a _South_ and _West_-wind.
10. I tryed several times, by strong fumes and thick smoaks to alter the
Air in my Closet; but I cannot affirm, that the _Mercury_ yielded any more,
then might be expected from some increase of heat. Such as have exact
_Wheel-Barometers_, may try whether Odors or Fumes do alleviate the Air.
11. In this Closet I have not in all this time found the extreamest changes
of the Quicksilver to amount to more, than to 23/4, or to 2-7/8. inches, at
most.
12. Very often I have found great changes in the Air, without any
perceptible change in the _Barometer_; as in the dewy nights, when the
moisture descends in a great quantity, and the thickness sometimes seems to
hide the Stars from us: In the days foregoing, and following, the Vapors
have been {158} drawn up so _Invisibly_, that the Air and Sky seem'd very
clear all day long. This I account a great change between ascending and
descending Dews and Vapors (which import Levity and Weight,) and between
thick Air and clear Air: which changes do sometimes continue in the
Alternative course of day and night, for a week or fortnight together; and
yet the _Baroscope_ holding the same.
13. Sometimes (I say not often) the _Baroscope_ yields not to other very
great changes of the Air. As lately (_December_ 18.) an extraordinary
bright and clear day; and the next following quite darkened, some Rain and
Snow falling; but the _Mercury_ the same: so in high winds and calms the
same.
14. I do conceive, that such as converse much _Sub dio_, and walk much
abroad, may find many particulars much more exactly, then I, who have no
leisure for it, can undertake. To instance in one of many, _December_ 16.
last, was a clear cold day, very sharp and strong _East_ wind, the
_Mercury_ very near 30. inches high, about three in the afternoon, I saw a
large black cloud, drawing near us from the _East_ and _South-East_, with
the _East-wind_. The _Mercury_ changed not that day nor the day following;
the Stars and most of the sky were very bright and clear till Nine of the
Clock; and then suddenly all the sky was darkned, yet no change of weather
happened; _December_ 17. the frost held, and 'twas a clear day, till about
two of the clock in the afternoon; and then many thick clouds appear'd low
in the _West_; yet no change of the weather here; the Wind, Frost, and
Quick-silver, the same, _December_ 18. the _Mercury_ fell almost 1/4 of an
inch, and the sky and Air so clear and bright and cold with an _East-wind_,
that I wondred what could cause the _Mercury_ to descend. I Expected, it
should have ascended, as usually it does in such clear skys. Casually I
sent my servant abroad, and he discovered the remote Hills, about 20. miles
off, cover'd with {159} snow, This seem'd to manifest, that the Air, being
discharged of the clouds by snow, became lighter.
15. I have seldom seen the change to be very great, at any one time. For,
though I do not now take a deliberate view of my Notes, yet I wonder'd once
to see, that in one day it subsided about 3/4 of an inch.
16. Of late I have altered my Method upon the _Barometer_, observing it, as
it is before my Eyes, all day long, and much of the night, being watchful
for the moments of every particular change, to examine, what cause in the
Air and Heavens may appear for such changes. And now my wonder is, to see,
how slow it is, it holding most between the nine and twentieth and
thirtieth inch of late.
17. I must now (_January_ 13. 1665/6) tell you, that the _Mercury_ stands
at this time (as it did also yesterday) a quarter above 30. inches; yet
both days very dark and cloudy, sometimes very thick and misty Air; which
seldom falls out. For, for the most part, I see it higher in clearest
setled weather, than in such cloudy and misty Foggs. This thick Air and
darkness hath lasted above a week; lately more Cold, and _East_ and
_North-East_ wind.
[Sidenote: _This seems to be wished, because the motion of the _Mercury_
may be more free in a wider Cane._]
_Thus far_ the Notes of this Observing _Divine_; of which Mr. _Boyle_, to
whom they were also communicated, entertains these thoughts, that they seem
to him very faithfully made, and do for the main, agree well enough with
his observations, as far as he remembers, not having them, it seems, at
that time, when he wrote this, at hand; and though it be wished by him,
that the Observer's Glass-Cane had been somewhat bigger; yet his diligence
in fitting it so carefully, or rather so skilfully, as is above-mentioned,
is much by him commended. {160}
* * * * *
_Some Observations of _Vipers_._
A curious _Italian_, called _Francesco Redi_, having lately had an
opportunity, by the great number of Vipers, brought to the _Grand Duke_ of
_Toscany_ for the composing of _Theriac_ or _Treacle_, to examine what is
vulgarly delivered and believed concerning the Poyson of those Creatures,
hath, (according to the account, given of it in the French _Journal des
Scavans_, printed _January_ 4. 1665/6) performed his undertaking with much
exactness, and published in an Italian tract, not yet come into _England_,
these Observations.
1. He hath observed, that the poyson of Vipers is neither in their _Teeth_,
nor in their _Tayle_, nor in their _Gall_: but in the two _Vesicles_ or
_Bladders_, which cover their teeth, and which coming to be compressed,
when the Vipers bite, do emit a certain yellowish Liquor, that runs along
the teeth and poysons the wound. Whereof he gives this proof, that he hath
rub'd the wounds of many Animals with the _Gall_ of Vipers, and pricked
them with their _Teeth_, and yet no considerable ill accident follow'd upon
it, but that as often as he rubbed the wounds with the said yellow Liquor,
not one of them escaped.
2. Whereas commonly it hath hitherto been believed, that the poyson of
Vipers being swallowed, was present death; this _Author_, after many
reiterated Experiments, is said to have observed, that in Vipers there is
neither Humour, nor Excrement, nor any part, not the _Gall_ it self, that,
being taken into the Body, kills. And he assures, that he hath seen men
eat, and hath often made Bruit Animals swallow all that is esteem'd most
poysonous in a Viper, yet without the least mischief to them. Whence he
shews, that it needs not so much to be wondred at, that certain _Empiricks_
swallow the juyce of the {161} most venomous Animals without receiving any
harm thereby; adding, that, which is ascribed to the vertue of their
_Antidote_, ought to be attributed to the nature of those kinds of Poysons,
which are no poysons, when they are swallow'd, (for which Doctrine he also
alledges _Celsus_) but onely when they are put into wounds. Which also has
been noted by _Lucan_, who introduces _Cato_ thus speaking;
_Noxia serpentum est admisto sanguine pestis,_
__Morsu_ virus habent, & fatum _dente_ minantur;_
__Pocula_ morte carent._
And what also some Authors have affirm'd, _videl._ That it is mortal, to
eat of the Flesh of creatures killed by Vipers; or to drink of the Wine
wherein Vipers have been drowned; or to suck the wounds that have been made
by them, is by this Authour observed to be wide of truth. For he assures,
that many persons have eaten Pullets and Pigeons, bitten by Vipers, without
finding any alteration from it in their health. On the contrary, he
declares, That it is a soveraign Remedy against the biting of Vipers, to
suck the wound; alledging an Experiment, made upon a Dog, which he caused
to be bitten by a Viper at the nose, who by licking his own wound saved his
life. Which he confirms by the example of those people, celebrated in
_History_ by the name of _Marsi_ and _Psilli_, whose Employment it was, to
heal those, that had been bitten by Serpents, by sucking their wounds.
3. He adds, that although _Galen_ and many modern _Physitians_ do affirm,
that there is nothing, which causeth so much thirst, as Vipers-flesh, yet
he hath experimented the contrary and knows divers persons, who did eat the
flesh of Vipers at all their meals, and yet did assure him, they never were
less dry, then when they observed that kind of Diet.
4. As for the Salt of Vipers, whereof some _Chymists_ have {162} so great
esteem, he saith, that it hath no _Purging_ vertue at all in it; adding
that even of _All Salts_, none hath more vertue than another, as he
pretends to have shew'd in an other _Book_ of his, _De natura salium_;
which also hath not been yet transmitted into these parts.
5. He denies, what _Aristotle_ assures, and what _Galen_ saith to have
often tryed, that the _Spittle_ of a _Fasting_ person kills Vipers; and he
laughs at many other particulars, that have been delivered concerning the
_Antipathy_ of Vipers unto certain things; and their manner of Conception
and Generation, and several other properties, commonly ascribed to them;
which the alledged French Author affirms to be refuted by so many
experiments made by this _Italian_ Philosopher, that it seems to him, there
is no place left for doubting, after so authentick a testimony.
* * * * *
_Advertisement._
The _Reader_ of these _Transactions_ is desired to correct these _Errata_
in _Number_ 8. _viz._ page. 132. line penult. read _Wine_ for _Lime_; and
page 133. line 10. read _Thresher_ for _Trepher_, as some _Copies_ have it;
and page 136. line ult. read _purifie_ for _putrifie_.
* * * * *
_LONDON,_
Printed for _John Martyn_ and _James Allestree_, Printers to the Royal
Society. 1666.
{163}
* * * * *
_Num._ 10.
PHILOSOPHICAL
_TRANSACTIONS._
* * * * *
_Munday_, _March_ 12. 1665/6.
* * * * *
The Contents.
_Observations continued upon the _Barometer_, or _Ballance of the Air_.
A Relation concerning the _Earth-quake_ neer _Oxford_; together with
some Observations of the sealed _Weatherglass_ and _Barometer_
thereupon by _Dr. Wallis_. A more full and particular Account of those
Observations about _Jupiter_, that were mention'd in Numb. 8. An
Account of some Books, lately publisht, _videl._ Mr. _Boyles_
Hydrostatical Paradoxes; _Steno_ de Musculis & Gladulis; _De Graeff_ de
Natura & Usu Succi Pancreatici._
* * * * *
_Observations continued upon the _Barometer_, or rather _Ballance of the
Air_._
These _Transactions_ being intended, _not only_ to be (by parcels) brief
Records of the Emergent Works and Productions in the Universe; Of the
Mysteries of Nature of later discoveries; And, of the growth of Useful
Inventions and Arts; _but_ also, and chiefly, to sollicite in all parts
mutuall Ayds and Collegiate endeavours for the farther advancement thereof:
We shall begin this _Second_ year of our Publications in this kind (in
which, for 3-moneths the Printing-presses were interrrupted by the publick
Calamity) with a few more particular Observations upon the _Ballance of the
Air_, as they are most happily invented and directed by Mr. _Boyle_; and
deserve to be prosecuted with care and diligence in all places.
But it is to be premised, that the Worthy person, who was alledged as the
Author of the Observations, delivered of this kind in the last of these
_Tracts_ (Dr. _Beale_) gives notice, That {164} he did not pretend to
exactness, but only to excite the carefulness of others in the several
distant places, and chiefly such, as can have the assistance of a
_Wheel-ballance_ perfectly filled: without both which aids he hopes not to
obtain all the benefits and mysteries of this Invention.
This being thus briefly intimated, the Account of the Observations
themselves, as they were extracted out of a late Letter of the same Person,
are, as followes:
[Sidenote: __Hygroscopes_ are Instruments, to discover the degrees of
Moisture and Drought of the Air._]
1. As I have fitted and filled the _Single Cane_, I can say in the general,
That I have not yet found any such infallible Prognostick of these changes
of weather, which do follow a long serenity, or setled weather. And
perchance in brighter Climats it may be constantly infallible. In these
_Northern Islands_, the Clouds are so short, and narrow, and by fickle
changes are sometimes emptied upon us, sometimes so neer, as may make so
little variation in the weight of the whole Atmosphere of Air, as may
sometimes deceive us, or smother and hide from us the causes of fixedness,
or of changes. I wish I could see a good _Calendar_ or _Journal_ taken in
taken in _Tangier_, and in some of our _Northern_ and most _Southern_ parts
of _America_. I have store of _Hygroscopes_ of divers kinds; and I do
remark them, and the sweatings of Marble, and as many other famed
Prognosticks, as I can hear off; but can find nothing so neerly indicative
of the change of weather, as this _Ballance_. Those others are often
changed by Dews, which do not at all alter the _Ballance_, nor alter the
state of the weather: And the open Weather-glass is known to signifie
nothing at certainty, having a double obedience to two Masters, sometimes
to the _Weight of the Air_, sometimes to _Heat_, as the service is
commanded.
2. And in further confirmation of this Note, I may adde to the former, That
in _January_ last 1665/6, from the _fourth_, and more especially from the
_seventh_ day, for many daies it continued very dark, so that all men
expected daily great rain; yet the _Mercury_ held very high, neer to the
greatest height; And though in those daies sometimes thick mists arose, and
some small rain fell, yet the _Quick-silver_ held at a great height: which
did indicate to me, there could _then_ be no great change of weather. As
the small rain fell, it yeilded somewhat, not much; and that does more
{165} confirm the indication. And more lately, in very dark daies, I had
the same confidence upon the same ground, and I was not disappointed.
3. Again, if the _Mercury_ ascends to a good height after the fall of rain
(as sometimes, but less often it does) then I look for a setled serenity;
but if it proceeds after rain in a descending motion, then I expect a
continuance of broken and showry weather. But in all, as I only say, _For
the most part_, so I dare not positively declare it an affirmative result,
but do refer it to the remarks of others. And this may explicate the Notes
6. and 14 of _Num._ 9. into more clearness.
4. That we find the Weather and our Bodies more chill, cold, and drooping,
when the _Mercury_ is lowest, and the Air lightest, besides other causes, I
guess, That as Air is to us the breath of life, as water is to Fishes; so,
when we are deprived of the usual measure of this our food, 'tis the same
to us, as when the water is drawn ebb from Fishes. But I would much rather
be instructed by others, then offer much in this kind.
5. The lowest descent of the _Mercury_ in all the time, since I have
observed it, was _Octob._ 26. 1665. in the Evening, when it was very near
at 271/2 Inches. Which I find thus circumstanced with the weather in my
notes.
_Oct._ 25. Morning; _Mercury_ at 281/2 Inch. Great storms and much rain.
_Oct._ 26. Morning; _Merc._ at 28. winds quiet, thick dark clouds.
_Oct._ 26. Evening; _Merc._ at 271/2. That day, and some daies following,
the weather was variable, frequent rain, and as you see, the _Mercury_
lower, than usual.
6. Over the place, where this _Mercurial Cane_ stands, I have set a _Wind
vane_, with purpose of exactness, of a Streamer in Brass so large, and
pointing to a Board indented in the Margin, that I can at a sure Level upon
the _Vane_, take every of the 32. points of the Wind, half points, and
quarter points, at good distance. Otherwise we may find our guesses much
deceived, as the best guessers, upon trial, do acknowledge. And this
exactness may become the _Wheel-ballance_, which shews the minutest
variations almost beyond imagination. And thus any servant, at the approach
of a thick Cloud, or other _Meteor_, higher or lower, or at the rising of a
storm or fresh wind in the night, or day, may bring a report of the Weight
of the Air, as certainly and almost as {166} easily, as of the Sun from the
_Dial_ in a Sunshine. It were good to have an _Index_ of Winds, that
discover'd as well their Ascent and Descent, as their Side-coastings.
* * * * *
_A Relation concerning the late _Earthquake_ neer _Oxford_; together with
some Observations of the sealed Weatherglass, and the Barometer both upon
that _Phaenomenon_, and in _General_._
This Relation was communicated by the excellently learned Dr. _Wallis_, as
follows:
On the 19. of _January_ 1665. _Stylo Angliae_ (or _Jan._ 29. 1666. _stylo
novo_) at divers places neer _Oxford_, was observed a small _Earthquake_
(as at _Blechington, Stanton-St. Johns, Bril_, &c.) towards evening. In
_Oxford_ it self, I doe not hear, that it was observ'd to be an Earthquake;
yet I remember about that time (whether precisely then or not; I cannot
say) I took notice of some kind of odde shaking or heaving I observed in my
study, but did impute it to the going of Carts or Coaches, supposed to be
not far off; though yet I did take notice of it, as a little differing from
what is usual on such occasions; (and wondered the more, that I did not
hear any:) But not knowing, what else to refer it to, I thought no more of
it. And the like account I have had from some others in _Oxford_, who yet
did not think of an Earth-quake; it being a rare thing with us. Hearing
afterwards of an Earthquake observed by others; I looked on my Notes
concerning my _Thermoscope_ and _Baroscope_, to see if any alteration
considerable had then happened.
My _Thermoscope_ consists of a round large Glass, containing about half a
pint or more; from whence issues a long Cylindrical neck of Glass, about
two foot and a half in length, and less than a quarter of an inch diameter;
which neck was _hermetically_ sealed at the top, to exclude communication
with the External Air; but before the sealing of it, the whole Glass was
filled with _Spirit of Wine_ (tinged with _Cochineel_, to make it the more
discernable to the Eye) so warmed, that it filled the whole content of the
Glass; but afterwards, as it cooled, did so subside, as to leave a void
space in the upper part of the Neck. Which Instrument, so prepared, doth by
the rising or falling of the tinged liquor in the neck (consequent upon the
expanding or contracting of the whole liquor contained in it and the Ball
below) give a very nice account of the Temperature of the Air, {167} as to
_Heat_ or _Cold_: Even so nice, as that my being or not being in my Study I
find to vary its hight sometimes almost a quarter of an inch.
My _Baroscope_, I call another Instrument for estimating the _Weight_ or
_Pressure_ of the Incumbent Air, consisting of a long _Glass-tube_ of about
4. foot in length, and about a quarter of an inch Bore: which tube
(_hermetically_ sealed at the one end) being filled with Quicksilver
(according to the _Torricellian_ Experiment) is inverted, so as to have the
open end of it immersed in Stagnant Quicksilver, contained in a larger
Glass under it, exposed to the pressure of the outward Air: Out of which
open end (after such immersion) the Quicksilver in the Tube being suffered
to run out, as much as it will, into the Stagnant Quicksilver, in which
that mouth or open end is immersed, there is wont to remain (as is commonly
known to those acquainted with this Experiment) a Cylinder of Quicksilver
suspended in the Tube, about 28, 29, or 30. inches high; measuring from the
surface of the Stagnant Quicksilver perpendicularly; (but more or less,
within such limits, according as the Weight or Pressure of the Air
incumbent on the External Stagnant Quicksilver exposed to it, is greater or
less:) leaving the upper part of the Tube void. (Both which Instruments
being the contrivance of the Honourable _Robert Boyle_, they are by him
more particularly described in his _Physico-Mechanical Experiments touching
the Air, Exper._ 17. and 18. and in his _Thermometrical Discourses_,
premised to his _History of Cold_.)
Now, according to both these Instruments, having kept a daily _Register_ of
Observations for more than a whole year (saving when I have been for some
short time absent from home) I find my Notes for that day to be these.
_January._ |_Thermoscope._|_Baroscope._ 1665/6.
Day. Hour. | inches. | inches.
19. 8. Morn. | 14-1/16. | 29-1/2. Hard frost. Close.
4. Even. | 14-3/8. | 29-1/4. Hard frost. Cloudy.
9. Even. | 14-3/4. | 29-3/4. Rain. Wind
20. 8. Morn. | 15-1/4. | 28-3/4. Sunshine. Wind.
So that, there being in the morning (_January_ 19.) a hard frost (which
began the day before about 4. of the Clock in the {168} afternoon (_Jan._
18.) and continued (with us) till about 5. of the Clock in the afternoon of
that day, _Jan_ 19. with some fierceness) and the weather, _Jan._ 19. being
in the morning, close; and cloudy all the day, with little of Sun-shine;
the Liquor in the _Thermoscope_ was very little raised, by 4. of the Clock
afternoon, that is, but 5/16 of an inch (which, had the Sun shone, would,
it's likely, have been near an Inch:) and after that time (or somewhat
before) had there been no considerable change of weather, it would upon the
Sun's setting have fallen (and probably so it did, till about 5. of the
Clock, though I took no Observation in the interim.) But, contrary to what
would have been expected, it was at 9. of the Clock at night, higher by 1/8
of an inch, than it had been at 4. occasioned by the change of weather, the
Frost suddenly breaking, with us, between 5. and 6. of the Clock; about
which time also it began to rain, and continued raining that Evening and
good part of the Night. And the next morning I found the Liquor yet higher
by half an inch, _vid._ 151/4 inches: (by reason of the Air that night being
so much warmer, than it had been the day before;) whereas commonly it is
considerably lower in the morning, than over night.
As to the _Baroscope_, for the Weight or Pressure of the Air; I find, that
for the 11, l2, 13, 14, 15, 16, and 17. dayes, the _Mercury_ in the Tube,
was (by the ballancing Pressure of the incumbent Air on the stagnant
Quicksilver, exposed to it) kept up to the height of near 30. Inches above
the surface of the External Quicksilver, (though with some little
variation, as 30, 29-15/16, 29-7/8, 29-13/16 but never so low, all that
time, as 293/4;) which is the greatest height I have know it at, (for I do
not find that I have ever, till then, observed it to be, in my Glasses,
full 30. Inches, though it have been very near it:) the Weather having been
almost continually Foggy, or very thick Mists, all that time. _January_ 18.
it came down to 293/4, in the forenoon; and afternoon, to 29-11/16. about the
time the frost began: And _Jan._ 19. it was, at 8. in the morning, come
down to 291/2; at 4. in the afternoon, to 291/4. But at 9. in the evening (when
the Earth quake had intervened) it was risen half an inch, _vid._ to 293/4.
And, by the next morning, fallen again a whole inch, _vid._ to 283/4; which
fall I attribute (at least in part) to the rain that fell in the night.
This being what I observed out of my _Register_ of these Instruments,
(which, if I had then thought of an Earthquake, I {169} should have more
nicely watched) what I have further gathered from Reports, is to this
purpose.
I hear, it was observed at _Blechington_, above 5. miles to the _North_ of
_Oxford_, and so along by _Bostol_, _Horton_, _Stanton-St. Johns_, and so
towards _Whately_, which is about 4. miles _Eastward_ from _Oxford_. Not at
all these places at the same time, but moving forward from _Blechington_
towards _Whately_. For it was at _Stanton_ about 6. of the Clock or later
(as I understand from Mr. _Boyle_, who was there at that time;) but had
been at _Blechington_ a good while sooner. And I am told, that it was taken
notice of by Doctor _Holder_ (a Member of our _Society_) who was then at
_Blechington_, to be observed by those in the further part of the Garden,
some very discernable time before it was observed by those in the House;
creeping forward from the one place to the other. What other places in the
Country it was observed at, I have not been informed: but at _Oxford_
(which, it seems, was about the skirts of it) it was so small, as would
have been hardly noted at all, had not the notice, taken of it abroad,
informed us of it.
Upon this Occasion, it will not be unseasonable to give some General
accounts of what I have in my _Thermoscope_ and _Baroscope_ observed.
My _Thermoscope_, being fitted somewhat at adventures, I have found at the
lowest to be somewhat more than 12. inches high, in the fiercest time of
the long Frost in the beginning of the last year 1665. and about 27. Inches
high, at the highest, in the hottest time of the last Summer: (which I
mention, that it may appear at what temperature in proportion, the Air was
at the time above-mentioned.) But I must add withall, that this standing
so, as never to be exposed to the Sun, but in a room, that has a window
only to the North, it would have been raised much higher than 27. inches,
if it were put in the hot Sun-shine in Summer; this, as it is placed,
giving therefore an account onely of the Temperature of the Air in
_general_, not of the immediate heat of the Sun-shine.
This Instrument, thus situated, when it is about 15. inches, or lower, is
for the most part hard frost; but seldom a frost, if higher than 16. Yet
this I have often observed, that the Air by the _Thermoscope_ has appeared
considerably colder (and the liquor lower) at sometimes when there is no
Frost, than at some other times, when the Frost hath been considerably
hard. {170}
In my _Baroscope_, I have never found the Quicksilver higher than 30.
inches, nor lower than 28. (at least, scarce discernably, not 1/16 of an
inch higher than _that_, or lower than _this_;) which I mention, not only
to shew the limits, within which I have observed mine to keep, _vid._ full
2 inches, but likewise as an Estimate of the Clearness of the Quicksilver
from Air. For, though my Quicksilver were with good care cleansed from the
Air; yet I find that which Mr. _Boyle_ useth, much better: for, comparing
his with mine at the same times, and both in _Oxford_, at no great
distance; I find his Quicksilver to stand alwaies somewhat higher than mine
(sometimes neer a quarter of an Inch;) which I know now how to give a more
probable account off, than that my Quicksilver is either heavier than his;
or else, that his is better cleansed from Air, (unless, possibly, the
difference of the Bore, or other circumstances of the Tube, may cause the
alteration; mine being a taller Tube, and a bigger Bore, than his.) And
upon like reason, as his stands higher than mine; so another less cleansed
from Air, may at the same time be considerably lower, and consequently
under 28. Inches at the lowest.
In _thick foggy_ weather, I find my Quicksilver to rise; which I adscribe
to the heaviness of the Vapours in the Air. And I have never found it
higher, than in the foggy weather above-mentioned.
In _Sunshiny_ weather it riseth also (and commonly the clearer, the more;)
which, I think, may be imputed _partly_ to the Vapors raised by the Sun,
and making the Air heavier; and _partly_ to the Heat, increasing the
Elastick or Springy power of the Air. Which latter I the rather add,
because I have sometimes observed in Sunshiny weather, when there have come
Clouds for some considerable time (suppose an hour or two) the Quicksilver
has fallen; and then, upon the Suns breaking out again, it has risen as
before.
In _Rainy_ weather, it useth to fall (of which the reason is obvious,
because the Air is lightned, by so much as falls:) In _Snowy_ weather,
likewise, but not so much as in _Rain_. And sometimes I have observed it,
upon a _Hoar-frost_, falling in the night.
[Sidenote: * _The Author of these Observations intends hereafter more
particularly to observe, _from what points_ those Winds blow, that make the
Quicksilver thus subside._]
For _Windy_ weather, I find it _generally_ to fall; and that more
universally, and more discernably, than upon Rain: (which I attribute to
the Winds moving the Air _collaterally_, and thereby not suffering it to
press so much _directly_ downwards: the like of {171} which we see in
swimming, &c.) And I have never found it lower than in high Winds.*
I have divers times, upon discerning my Quicksilver to fall without any
visible cause at home, looked abroad; and found (by the appearance of
broken Clouds, or otherwise) that it had rained not far off, though not
with us: Whereupon, the Air being then lightened, our heavier Air (where it
rained not) may have, in part, discharged it self on that lighter.
* * * * *
_A more particular Account of those Observations about _Jupiter_, that were
mentioned in _Numb. 8_._
Since the publishing of _Numb._ 8. of these _Transactions_, where, among
other particulars, some short Observations were set down touching both the
_shadow_ of one of _Jupiter's Satellits_, passing over his Body, and that
_Permanent Spot_, which manifests the Conversion of that Planet about his
own _Axis_; there is come to hand an _Extract_ of that Letter, which was
written from _Rome_, about those Discoveries, containing an ample and
particular Relation of them, as they were made by the Learned _Cassini_,
Professor of _Astronomy_ in the University of _Bononia_. That _Extract_, as
it is found in the _French Journal des Scavans_ of _Febr._ 22. 1666. we
thus _English_.
Monsieur _Cassini_, after he had discovered (by the means of those
Excellent Glasses of 50. _palmes_, or 35. _feet_, made by M. _Campani_) the
_Shadows_, cast by the 4 Moons or _Satellits_ of _Jupiter_ upon his Diske,
when they happen to be between the Sun and Him; after he had also
distinguished their Bodies _upon_ the Diske of _Jupiter_; made the last
year some Praedictions for the Months of _August_ and _September_, noting
the dayes and hours, when the Bodies of the said _satellits_ and their
_Shadows_ should appear upon _Jupiter_, to the end that the Curious might
be convinced of this matter by their own Observations.
Some of these Praedictions have been verified not only at _Rome_, and in
other places of _Italy_, but also at _Paris_ by M. _Auzout_, the most
Celebrated and the most Exact of our _Astronomers_; and in _Holland_, by M.
_Hugens_. And we can now doubt no longer, of the rotation of the
_Satellits_ about _Jupiter_, as the Moon turns about the Earth; nor
believe, that _Jupiter_ or his _Attendants_ have any other Light, than
that, which they receive from the Sun; as some did {172} assure before
these Observations. There remained to find by Experience, whether _Jupiter_
did turn about his _Axis_, as many believe, that the _Earth_ turns about
her's. And although most _Astronomers_ had conjectur'd, it did so, either
by this Analogy, or by other Congruities, yet it was much wish'd, that we
might be assured thereof by Observations. And this it is, for which we are
obliged to M. _Cassini_, who, having by the advantage of the same Glasses
discover'd several changes, as well in the three obscure _Belts_, commonly
seen in _Jupiter_, as in the rest of his _Diske_, and having also observed
Spots in the midst of that _Planet_, and sometimes _Brightnesses_, such as
have bin formerly seen in the _Sun_, hath at length discover'd a _Permanent
Spot_ in the _Northern_ part of the most _Southern_ Belt; by the means
whereof, he hath concluded, that _Jupiter_ turns about his _Axis_ in 9.
hours, 56. minutes, and makes 29. whole circumvolutions in 12 dayes 4.
minutes of ours, and 360 in 149. dayes. For he has found, that this _Spot_
was not caused by the Shadow of any _Satellit_, as well by reason of its
Situation, as because it appeared, when there could be no Shadow. Besides,
that its motion differed from that of the Shadows, which is almost equal,
as well towards the Edges as towards the Middle of _Jupiter_: Whereas, on
the contrary, this _Spot_ hath all the accidents, that must happen to a
thing, which is upon the surface of a round Body moving; for example, to
move much more slowly towards the Edges, than towards the Middle, and to
pass over that part, which is in the middle of the Diske, equal to the half
of the _Diameter_, in the sixth part of the time, it takes to make the
whole revolution: he having seen this half pass'd over, in 99 or 100
minutes just, as it must happen, supposing the whole circumrotation is made
in 9. hours 56. minutes.
He hath not yet been able to determine the Situation of the _Axis_, upon
which this motion is made, because the _Belts_, according to which it is
made, have for some years appeared streight, though in the precedent years,
other _Astronomers_ have seen them a little crooked: Which sheweth, that
the _Axis_ of the diurnal motion of _Jupiter_ is a little inclined to the
plain of the _Ecliptick_. But in time we may discover, what certainty there
is in this matter.
[Sidenote: _These _Tables_ are not yet sent over, but, 'tis hoped, will be,
ere long._]
After this excellent Discovery, he hath calculated many _Tables_, whereof
he gives the Explication and Use in the Letters by him addressed to the
Abbot _Falconieri_. By the means of them, one may know, _when_ this _Spot_
may be seen by us. For, having first {173} considered it in relation to the
_Sun_, in respect whereof, its motion is regular, he considers the same in
relation to the _Earth_, where _We_ observe it; and shews by the means of
his _Tables_, what is to be added or subtracted, to know, at what time the
said _Spot_ is to come into the middle of _Jupiter_'s Diske, according as
he is Oriental or Occidental. He hath also considered it in relation to an
unmovable point, which he has supposed to be the first point of _Aries_,
because we thither refer here upon Earth the beginning of all the Celestial
motions, and _there_ is the _Primum mobile_, that one would imagine, if we
were in _Jupiter_, as we do here imagine Ours of 24. hours.
The Discovery is one of the best, that have been yet made in the Heavens;
and those, that hold the Motion of the earth, find in it a full Analogy.
For, _Jupiter_ turning about the Sun, does nevertheless turn about his
_Axis_; and although he be much bigger than the Earth, he does nevertheless
turn much more swiftly than it, since he makes more than two Turns, and a
third part, for its one; and carries with him 4. Moons, as the Earth does
one.
This Observation ought to excite all Curious persons to endeavour the
perfecting of _Optick Glasses_, to the end that it may be discovered,
whether the other _Planets_, as _Mars_, _Venus_ and _Mercury_, about whom
no Moon hath as yet been discovered, do yet turn about their _Axes_, and in
how much time they do so; especially _Mars_, in whom some _Spot_ is
discover'd, and _Venus_, wherein M._Burattini_ hath signified from
_Poland_, he has observ'd Inequalities, as in the Moon.
It will be worth while, to watch for the seeing of _Jupiter_ again this
Spring, that this happy Observation may be confirmed in divers places, and
endeavours used to make new ones.
* * * * *
_An Account of some Books, lately published._
I. _Hydrostatical Paradoxes, made out by New Experiments (for the most part
Physical, and Easie) by the Honourable Robert Boyle._ This Treatise,
promised in _Numb._ 8. of these Papers, is now come forth: And was
occasioned by the perusal of the Learned Monsieur _Paschalls_ Tract, _Of
the AEquilibrium of Liquors_, and of the _Weight of the Air_: Of which two
Subjects, the _latter_ having been more clearly made out in _England_ by
Experiments, which could not be made by Monsieur _Paschal_ and others, that
wanted the advantage of such Engines and Instruments, as have here been
frequently made use {174} off; Our Noble Author insists most upon giving us
his thoughts of the former, _videl._ the _AEquilibrium of Liquors_: Which
Discourse consisting partly of _Conclusions_, and partly of _Experiments_,
the _former_ seem to Him to be almost all of them consonant to the
Principles and Laws of the _Hydrostaticks_; but as for the _latter_, the
Experimental proofs, offered by M. _Paschall_ for his Opinions, are by our
Author esteemed such, that he confesses, he hath no mind to make use of
them: for which he alledges more reasons than one; which, doubtless, will
appear very satisfactory to Intelligent _Readers_.
Wherefore, instead of the those _Paschalian_ Experiments, there is in this
_Treatise_ deliver'd a far more Expeditious way, to make out, _not only_
most of the _Conclusions_, agreed on these two Authors, _but_ others also,
that M _Paschall_ mentions not: and that with so much more ease and
clearness, that persons, but ordinarily versed in the common principles of
_Hydrostaticks_, may readily apprehend, what is deliver'd, if they will but
bring with them a due Attention, and Minds disposed to prefer Reason and
Experience to Vulgar opinions and Authors.
It not being our _Authors_ present Task, to deliver a Body of
_Hydrostaticks_, but only some _Paradoxes_, which he conceives to be
proveable by his New way of making them out, he delivers them in as many
distinct Propositions; after each of which, he endeavours, in a Proof, or
an Explication, to show, both that it is true, and why it ought to be so.
The _Paradoxes_ themselves (after a premised _Postulatum_) are these:
1. That in Water, and other Fluids, the Lower parts are pressed by the
Upper.