Chapter M: A Hook, on which the end of the Chain is fastned by a Ring, the (4)

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 27½ Inches. Which I find thus circumstanced with the weather in my notes.

_Oct._ 25. Morning; _Mercury_ at 28½ Inch. Great storms and much rain.

_Oct._ 26. Morning; _Merc._ at 28. winds quiet, thick dark clouds.

_Oct._ 26. Evening; _Merc._ at 27½. 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 _Phænomenon_, and in _General_._

This Relation was communicated by the excellently learned Dr. _Wallis_, as follows:

On the 19. of _January_ 1665. _Stylo Angliæ_ (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._ 15¼ 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 29¾;) 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 29¾, 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 29½; at 4. in the afternoon, to 29¼. But at 9. in the evening (when the Earth quake had intervened) it was risen half an inch, _vid._ to 29¾. And, by the next morning, fallen again a whole inch, _vid._ to 28¾; 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 Prædictions 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 Prædictions 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 Æquilibrium 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 _Æquilibrium 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.

2. That a lighter Fluid may gravitate or weigh upon a heavier.

3. That, if a Body, contiguous to the Water, be altogether, or in part, lower than the highest level of the said Water, the lower part of the Body will be pressed upward by the Water, that touches it beneath.

4. That in the Ascension of Water in Pumps, &c. there needs nothing to raise the Water, but a Competent weight of an External Fluid.

5. That the pressure of an External Fluid is able to keep an Heterogeneous Liquor suspended at the same height in several Pipes, though these Pipes be of very different Diameters.

{175}

6. If a Body be placed under Water, with its uppermost Surface parallel to the Horizon; how much Water soever there may be on this or that side above the Body, the direct pressure susteined by the Body (for we now consider not the Lateral nor the Recoyling pressure, to which the Body may be exposed, if quite environed with Water) is no more, than that of a Column of water, having Horizontal Superficies of the Body for its Basis, and the Perpendicular depth of the Water for its height.

And so likewise,

If the Water, that leans upon the Body, be contained in Pipes open at both ends, the pressure of the Water is to be estimated by the weight of a pillar of Water, whose Basis is equal to the lower Orifice of the Pipe (which we suppose to be parallel to the Horizon) and its height equal to a perpendicular, reaching thence to the top of the Water; though the Pipe be much inclined towards the Horizon, or though it be irregularly shap'd, and much broader in some parts, than the said Orifice.

7. That a Body, immersed in a Fluid, sustains a Lateral pressure from the Fluid; and that increased, as the depth of the immersed Body, beneath the Surface of the Fluid, increaseth.

8. That Water may be made as well to depress a Body lighter than it self, as to buoy it up.

9. That, whatever is said of Positive Levity, a parcel of Oyl lighter than Water, may be kept in Water without ascending in it.

10. That the cause of the Ascension of Water in Syphons, and of its flowing through them, may be explicated without having a recourse to Nature's abhorrency of a _Vacuum_.

11. That a Solid Body, as ponderous as any yet known, though near the Top of the water it will sink by its own weight; yet if it be placed at a greater depth, than that of twenty times its own thickness; it will not sink, if its descent be not assisted by the weight of the incumbent Water.

These are the _Paradoxes_, evinced by our Authour with much evidence and exactness, and very likely to invite Ingenious men to cultivate and to make further disquisitions in so excellent a part of Philosophy, as are the _Hydrostaticks_; and Art deserving great _Elogiums_, not only, upon the account of the _Theorems_ and _Problems_, which are most of them pure and handsome productions of Reason, very delightful and divers of them surprising, and besides, much conducing to the clear explication and {176} thorow-understanding of many both familiar and abstruse _Phænomena_ of Nature; but also, upon the score of its _Practical_ use, since the Propositions, it teaches, may be of great importance to Navigation, and to those that inquire into the Magnitudes and Gravities of Bodies, as also to them, that deal in Salt-works: Besides, that the _Hydrostaticks_ may be made divers waies serviceable to _Chymists_, as the Author intimates, and intends to make manifest, upon several occasions, in his yet unpublisht part of the _Usefulness of Natural and Experimental Philosophy_.

These Propositions are shut up by two important _Appendixes_, whereof the _one_ contains an Answer to seven Objections by a late learned Writer, to evince, that the upper parts of water press not upon the lower; the _other_, solves that difficult _problem_, why _Urinators_ or _Divers_, and others, who descend to the bottom of the Sea, are not oppressed with the weight of the incumbent water? where, among other solutions, _that_ is examined, which occurs in a printed Letter of Monsieur _des Cartes_, but is found unsatisfactory.

II. _Nicolai Stenonis de Musculis & Glandulis Observationum Specimen; cum duabus Epistolis Anatomicis_. In the _Specimen_ it self, the Author, having described in _general_, both the _Structure_ and the _Function_ of the _Muscles_, applies that description to the _Heart_, to demonstrate that _that_ is also a _true Muscle_: Observing _first_, that in the substance of the _Heart_ there appears nothing but _Arteries, Veins, Nerves, Fibres, Membrans_; and that that, & nothing else is found in a _Muscle_; affirming withall, that which is commonly taught of the _Muscles_, and particularly of the _Heart's Parenchyma_, as distinct from _Fibres_, is due, not to the _Senses_, but the _Wit_ of _Anatomists_: so that he will not have the _Heart_ made up of a substance peculiar to it self, nor considered as the principle of _Innate heat_, or of _Sanguification_, or of _vital spirits_. He observes _next_, that the _Heart_ performs the like _operation_ with the _Muscles_, to wit, to contract the Flesh; which action how it can have a different cause from that of the Contraction made in the _Muscles_, where there is so great a parity and agreement in the _Vessels_, he sees not. And as for the _Phænomena_, that occur, of the _Motion_ of the Heart, he undertakes to explicate them all, from the _Ductus_ or _Position_ of the _Fibres_; but refers for the performance of this undertaking to another _Treatise_, he intends to publish.

[Sidenote: __Conglobate_ Glanduls are called those, that do consist, as it were, of one continued substance, having an _even_ superficies; whereof there are many in the _Mesentery_, and in other places: contra distinguisht to those, that bear the name of _Conglomerate_ Glanduls, which are made up of several small Kernels, such as the _Pancreas_, the _Salivating Glanduls_, &c._]

As to his Observations about _Glanduls_, he affirms, that he has been the First, that has discover'd that Vessel, which by him is call'd {177} _Salivare Exterius_, passing from the _Parotides_ (or the two chief Arteries that are on the right and left side neer the Throat) into the Mouth, and conveying the _Spittle_: Where he also gives an account of several other Vessels and Glanduls, some about the _Lips_; others under the _Tongue_; others in the _Pallate_ &c. To which he adds the Vessels of the _Eye-lids_, which have their root in the _Glanduls_ that are about the Eyes, and serve for the _shedding of Tears_. He mentions also several things about the _Lymphatick vessels_, and is of opinion, that the knowledge thereof may be much illustrated by that kind of _Glanduls_ that are called _Conglobatæ_, and by their _true_ insertion into the veins; the mistake of the latter whereof, he conceives to have very much misled the Noble _Ludovicus de Bills_, notwithstanding his excellent method of _dissection_. And here he observes _first_, that all the _Lymphatick vessels_ have such a commerce with the _Glanduls_, that none of them is found in the body, which either has not its origine _from_, or is inserted _into_ a _Glandule_: And _then_, that _Glanduls_ are a kind of _Strainers_, so form'd, that whilst the Blood passes out of the Arteries into the Veins through the small _Capillary_ vessels, the _Serous_ parts thereof, being freed from the _Sanguineous_, are by vertue of the beat expell'd through fit pores into the _Capilaries_ of the _Lymphaticks_, the direction of the _Nerves_ concurring.

Of the two annex'd _Epistles_, the _First_ gives an account of the dissection of two _Raja's_ or _Skates_, and relates that the Author found in the bellies of these Fishes a _Haddock_ of 1½ span long, and a _Sole_, a _Plaise_, and nine middle-sized _Sea crafishes_; whereof not only the three former had their flesh, in the fishes stomack, turn'd into a _fluid_, and the Gristles or Bones into a _soft_ substance, but the _Crafishes_ had their shels comminuted into very small particles, tinging here and there the _Chyle_ near the _Pylorus_; which he judges to be done not so much by the heat of the Fishes stomack, as by the help of some digesting juyce. Coming to the _Uterus_ of these Fishes, he takes occasion to examine, with what ground several famous _Naturalists_ and _Anatomists_ have affirm'd, that Eggs are the _uterus_ exposed or ejected out of the body of the Animal. Taking a view of their _Heart_, he there finds but _one_ ventricle, and discourses of the difficulty arising from thence. As for the _Lungs_, he saw no clearer footsteps of them in these, than he had done in other Fishes: but within the mouth he trac'd several _gaping fissures_, and found the recesses of the _Gills_ so form'd, that the water taken in at the mouth, being let out by these dores, cannot by them re-enter, by reason of a skin outwardly passing over every hole, and covering it. Where he intimates, that though Fishes have not _true_ Lungs, yet they want not a _Succedaneum_ thereto, to wit, the _Gills_; and if _water_ may be to Fishes, what _Air_ is to terrestrial Animals, for Respiration: affecting, that whereas nothing is so necessary for the conservation of Animal life as a reciprocal Access and Recess of the _Ambient_ to the sanguineous vessels, tis all one, whether that be done by receiving the Ambient _within_ the body, or by its gentle passing _by_ the _Prominent_ vessels of the _Gills_.

The other _Epistle_, contains some Ingenious Observations, touching the way, by which the Chicken, yet in the shell, is nourish't, _videl._ not by the conveyance of the _Yolk_ into the _Liver_ by the _Umbilical_ vessels, nor into the _Stomack_ by the {178} _Mouth_, but by a Peculiar _ductus_, by him described, into the _Intestins_, where, according to his alledged experience, it is turn'd into _Chyle_: which he affirms, he hath discover'd, by taking an Egge from under a brooding Hen, when the Chicken was ready to break forth, and when he was looking for the passage of the _Yolk_, out of its integument into the _Liver_, by finding it pass thence into the _Intestins_, as he found the _White_ to do by the _mouth_ into the _belly_. Whence he inclines to infer, that, since every _fætus_ takes in at the mouth the liquor it swims in, and since the Chicken receives the _white_ of the Egge into the _mouth_, and the _yolk_ by the new discover'd _ductus_ into the _Intestins_, it cannot be certainly made out, that a _part_ of the _Chyle_ is conveyed into the _Liver_, before it passes into the _Heart_; Exhorting in the mean time the _Patrons_ of the _Liver_, that they would produce Experiments to evince their Ratiocinations.

III. _Regneri de Graeff, de Succi Pancreatici Natura & usu, Exercitatio Anatomico-medica._ In this Tract, the Industrious Author, after he has enumerated the various opinions of _Anatomists_ concerning the use of that kernelly substance; call'd _Pancreas_ (in _English_, the _Sweetbred_) endeavours to prove experimentally that this _Glandule_ was not form'd by Nature, to separate any _Excrementitious_ humor, and to convey it into the _Intestins_, but to prepare an _useful_ juyce out of the Blood and Animal Spirits, of a somewhat _Acid_ taste, and to carry the same into the Gut, call'd _Duodenum_, to be there mixt with the Aliment, that has been in some degree already fermented in the Stomack, for a further fermentation, to be produced by the conflux of the said acid _Pancreatick_ juyce and some _Bilious_ matter, abounding with volatile Salt, causing an Effervescence; which done, that juyce is, together with the purer part of the nourishment, carried into the _Milkie_ veins, thence into the _common receptacle_ of the _Chyle_ and _Lymphatick liquor_, and so through the _ductus Thoracicus_ into the right Ventricle of the Heart.

This Assertion, first advanced (saith the _Author_) partly by _Gothofredus Mobius_, partly by _Franciscus de le Boe Sylvius_, he undertakes to prove by experiments; which, indeed, he has with much industry, tried upon several Animals, to the end that he might collect some of this juyce of the _Pancreas_ for a taste: which having at last obtained, and found it somewhat _acid_, he thereupon proceeds to deliver his opinion both of the _constitution_ and quantity of this _Succus_ in _healthy_ Animals, and the vices thereof, in the _unhealthy_: deriving most diseases _partly_ from its too great Acidity, or from its saltness, or harshness; _partly_ from its paucity or redundancy: but especially, endeavouring to reduce from thence, as all _intermittent Feavers_ (of all the _Phænomena_ whereof he ventures to assign the causes from this _Hypothesis_) so also the _Gout, Syncope's, Stranguries, Oppilations, Diarrhæas, Dysenteries, Hysterical_ and _Colick passions_, &c. All which he concludes with mentioning the waies and remedies to cure the manifold peccancy of this juyce by Evacuations and Alterations.

This seeming to be a _new_ as well as a _considerable_ discovery, it is hop'd, that others will by this intimation be invited to prosecute the same by further experiments, either to confirm what this Author has started, if true, or to rectifie it, if he be mistaken.

* * * * *

_NOTE._

In _Fig._ 1. of _Num._ 9 of these Tracts the Graver hath placed the bended _end_ of the _Springing Wire_ C F, above the _Wire-staple_ B, between it and the _Ring_ E, of the _Weight_ D; whereas _that_ end should have been so expressed, as to pass _under_ the _Wire-staple_, betwixt its two Wires, into the said _Ring_.

* * * * *

_London_, Printed for _John Martyn_, and _James Allestry_, Printers to the Royal Society. 1666.

{179}

* * * * *

_Num._ 11.

PHILOSOPHICAL _TRANSACTIONS._

* * * * *

_Munday_, _April._ 2. 1666.

* * * * *

The Contents.

_A Confirmation of the former Account, touching the late _Earth-quake_
near _Oxford_, and the Concomitants thereof, by Mr. _Boyle_. Some
Observations and Directions about the _Barometer_, communicated by the
same Hand. General Heads for a _Natural History_ of a Country, small or
great, proposed by the same. An Extract of a Letter, written from
_Holland_, about _Preserving Ships from being Worm-eaten_. An Account
of Mr. _Boyle's_ lately publish't Tract, entituled, _The Origine of
Forms and Qualities_, illustrated by Considerations and Experiments._

* * * * *

_A Confirmation of the former Account touching the late _Earth-quake_ near _Oxford_, and the Concomitants thereof._

This Confirmation came from the Noble Mr. _Boyle_ in a Letter, to the _Publisher_, as followeth:

[Sidenote: * _See_ Num. 10. Phil. Transactions p. 166-171; _at the time of the printing whereof, this Relation of Mr._ Boyle _was not yet come to hand._]

As to the _Earth-quake_, your curiosity about it makes me sorry, that, though I think, I was the first, that gave notice of it to several of the _Virtuosi_ at _Oxford_; yet the Account, that I can send you about it, is not so much of the _Thing_ it self, {180} as of the _Changes of the Air_, that accompanied it. To inform you of which, I must relate to you, that riding one Evening somewhat late betwixt _Oxford_ & a Lodging, I have at a place, 4 miles distant from it, the weather having been for a pretty while Frosty, I found the Wind so very cold, that it reduced me to put on some defensives against it, which I never since, nor, if I forget not, all the foregoing part of the Winter was obliged to make use off. My unwillingness to stay long in so troublesome a Cold, which continued very piercing, till I had got half way home-ward, did put me upon galloping at no very lasy rate; and yet, before I could get to my Lodgings, I found the Wind turned, and felt the Rain falling; which, considering the shortness of the time, and that this Accident was preceded by a setled Frost, was surprising to me, and induced me to mention it at my return, as one of the greatest and suddainest Alterations of Air, I have ever observ'd: And what changes I found, have been taken notice of in the _Gravity_ of the _Atmosphere_ at the same time by that Accurate Observer * Dr. _Wallis_, who then suspected nothing of what follow'd; as I suppose, he has ere this told you himself. Soon after, by my guess about an hour, there was a manifest _Trembling_ in the House where I was (which stands high in comparison of _Oxford_.) But it was not there so great, but that I, who chanced to have my thoughts busied enough on other matters, than the weather, should not have taken notice of it as an _Earth-quake_, but have imputed it to some other cause, if one, that you know, whose hand is employed in this Paper, and begins to be a diligent observer of Natural things, had not advertis'd me of it; as being taken notice of by him and the rest of the people of the House. And soon after there hapned a brisk Storm: whereupon I sent to make inquiry at a place call'd _Brill_, which standing upon a much higher ground, I supposed might be more obnoxious to the effects of the _Earth-quake_ (of which, had I had any suspition of it, my having formerly been in one neer the _Lacus Lemanus_, would have made me the more observant:) But the person I sent to, being {181} disabled by sickness to come over to me (which he promis'd to do, as soon as he could) writ me only a _Ticket_, whose substance was, That the _Earth-quake_ was there much more considerable, than where I lodged, and that at a Gentlemans house, whom he names (the most noted Person, it seems, of the neighbourhood) the House trembled very much, so as to make the Stones manifestly to move to and fro in the Parlour, to the great amazement and fright of all the Family. The Hill, whereon this _Brill_ stands, I have observ'd to be very well stor'd with Mineral substances of several kinds; and from thence I have been inform'd by others, that this Earth-quake reach'd a good many miles; but I have neither leasure, nor inclination to entertain you with uncertain reports of the Extent and other Circumstances, especially since a little further time an inquiry may enable me to give you a better warranted account.

* * * * *

_Some Observations and Directions about the _Barometer_, communicated by the same Hand, to the _Author_ of this _Tract_._

These shall be set down, as they came to hand in another Letter; _videl._

[Sidenote: * _See _Num. 9_. of the _Phil. Transact_. p. 159 the last _paragraph_._]

As to the _Barometrical_ Observations (as for brevities sake I use to call them) though you * guessed aright, that, when I saw those of the Learned and Inquisitive Dr. _Beale_, I had not Mine by me, (for I left them, some years since, in the hands of a _Virtuoso_, nor have I now the leasure to look after those Papers;) yet since by the Communication, you have made publick, 'tis probable, that divers Ingenious men will be invited to attempt the like Observations, I shall (notwithstanding my present haste) mention to you some particulars, which perhaps will not appear unseasonable, that came into my mind upon the reading of what you have presented the Curious.

[Sidenote: * _Some whereof have been since invited by the _Publisher_, to give their concurrence herein_.]

When I did, as you may remember, some years agoe, publickly express and desire that some Inquisitive men would {182} make _Baroscopical_ Observations in several parts of _England_ (if not in forrain Countries * also;) and to assist them, to do so, presented some of my Friends with the necessary Instruments: The declared reason of my desiring this Correspondence was (among other things) that by comparing Notes, _the Extent of the Atmospherical Changes, in point of Weight, might be the better estimated_. But not having hitherto received some account, that I hoped for, I shall now, without staying for them, intimate thus much to you: That it will be very convenient, that the Observers take notice not only of the _day_, but as near as they can, of the _Houre_ wherein the height of the _Mercurial Cylinder_ is observ'd: For I have often found, that within less than the compass of one day, or perhaps half a day, the Altitude of it has so considerably vary'd, as to make it in many cases difficult, to conclude any thing certainly from Observations, that agree but in the day.

It will be requisite also, that the Observers give notice of the _Scituation of the place_, where their _Barometers_ stand, not only, because it will assist men to Judge, whether the Instruments were duely perfected, but principally, because, that though the _Baroscope_ be good (nay, because it is so) the Observations will much disagree, even when the _Atmosphere_ is in the same state, as to Weight, if one of the Instruments stand in a considerably higher part of the Countrey, than the other.

To confirm _both_ the foregoing admonitions, I must now inform you, that, having in these parts two Lodgings, the one at _Oxford_, which you know stands in a bottom by the _Thames_ side, and the other at a place four miles thence, seated upon a moderate _Hill_, I found, by comparing two _Baroscopes_, that I made, the one at _Oxford_, the other at _Stanton St. Johns_, that, though the former be very good, and have been noted for such, during some years, and the latter was very carefully fill'd; yet by reason, that in the _Higher_ place, the incumbent part of the _Atmosphere_ must be lighter, than in the _Lower_, there is almost {183} always between 2 and 3 Eights of an Inch difference betwixt them: And having sometimes order'd my servants to take notice of the Disparity, and divers times carefully observ'd it my self, when I pass'd to and fro between _Oxford_ and _Stanton_, I generally found, that the _Oxford Barometer_ and the _other_, did, as it were by common consent, rise and fall together so, as that in the former the _Mercury_ was usually 3/8 higher, than in the latter.

Which Observations may teach us, that the Subterraneous steams, which ascend into the Air, or the other Causes of the varying Weight of the _Atmosphere_, do, many times, and at least in some places, uniformly enough affect the Air to a greater height, than, till I had made this tryall, I durst conclude.

But, as most of the _Barometricall_ observations are subject to exception, so I found the formerly mentioned to be. For (to omit lesser variations) riding one evening from _Oxford_ to _Stanton_, and having, before I took horse, look't on the _Baroscope_ in the former of these 2. places, I was somewhat surprised, to find at my comming to the latter, that in places no farther distant, and notwithstanding the shortness of the time (which was but an hour and a half, if so much) the _Barometer_ at _Stanton_ was short of its usual distance from the _other_, near a quarter of an _Inch_, though, the weather being fair and calm, there appear'd nothing of manifest change in the Air, to which I could adscribe so great a Variation; and though also, since that time, the _Mercury_ in the two Instruments hath, for the most part, proceeded to rise and fall as before.

And these being the only Observations, I have yet met with, wherein _Baroscopes_, at some _Distance of Place_, and _Difference of Height_, have been compar'd (though I cannot now send you the Reflexions, I have else where made upon them;) as the opportunity I had to make them my self, rendred them not unpleasant to me, so perhaps the Novelty will keep them from being unwelcome to you. And I confess, I have had some flying suspicions, that the odd _Phænomena_ of the _Baroscope_, which have hitherto more pos'd, than instructed us, may in time, if a {184} competent number of Correspondents do diligently prosecute the Inquiries (especially with _Baroscopes_, accommodated with Mr. _Hooks_ ingenious additions) make men some _Luciferous_ discoveries, that possibly we do not yet dream off.

[Sidenote: * _This hath been inquired into, and is found, that several Accurate and Curious persons (as the Most Noble _President of the Royal Society_, the Lord Viscount _Brounker_, _Doctor Beale_, _Mr. Hook_ _&c._) have observed the same._]