# Philosophical Transactions of the Royal Society (1665-1886)/Volume 1/Number 10

Contents
* 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.
Num. 10.
PHILOSOPHICAL
TRANSACTIONS.
Munday, March 12. 166⁠5/6⁠.
The Contents.
Hese 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 interrupted 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 that 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 ​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:
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 Calender or Journal taken in Tangier, and in some of our Northern and most Southern parts of America, I have store of Hygroscopes Hygroscopes are Instruments, to discover the degrees of Moisture and Drought of the Air. 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 at 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 ​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.
Inch.
Oct. 25. Morning; Mercury at 28⁠1/2⁠. Great storms and much rain. Oct. 26. Morning; Merc. at 28. winds quiet, thick dark clouds. Oct. 26. Evening; Merc. at 27⁠1/4⁠. 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 ​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.
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 along 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, ​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 along 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 Torricelian 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 | January | Thermosocope | Baroscope | 166$\scriptstyle {\frac {5}{6}}$ | 166$\scriptstyle {\frac {5}{6}}$ |
| Day. | Hour | Inches. | Inches. | | |
| 19. | 8. Morn. | 14$\scriptstyle {\frac {1}{16}}$ | 29$\scriptstyle {\frac {1}{2}}$ | Hard frost. | Close |
| | 4. Even. | 14$\scriptstyle {\frac {3}{8}}$ | 29$\scriptstyle {\frac {1}{4}}$ | Hard frost. | Cloudy. |
| | 9. Even. | 14$\scriptstyle {\frac {3}{4}}$ | 29$\scriptstyle {\frac {3}{4}}$ | Rain. | Wind. |
| 20. | 8. Morn. | 15$\scriptstyle {\frac {1}{4}}$ | 28$\scriptstyle {\frac {3}{4}}$ | 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 ​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 ⁠4/16⁠ 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 ⁠3/8⁠ 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, 12, 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, 29⁠15/16⁠, 29⁠7/8⁠, 29⁠13/16⁠, 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 29⁠11/16⁠. about the time the frost began: And Jan. 19. it was, at 8. in the morning, come down to 29⁠1/2⁠ is 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 ​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 Eastwards 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.
​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.
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 ​which we see in swimming, &c.) And I have never found it lower than in high Winds.*
I have divers times, upon discerning *The Author of these Observations intends hereafter more particularly to observe from what points those Winds blow, that make the Quicksilver thus subside. my Quicksilver to fall without any visible cause at home, looked abroads 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 itself on that lighter.
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 de 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 ​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 discovered 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. dayes, 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.
After this excellent Discovery, he hath calculated many Tables, whereof he gives the Explication and Use in the Letters by him These Tables are not yet sent over, but, 'tis hoped, will be, ere long.addressed to the Abbot Falconieri. By the means of them, one may know, when this Spot may be seen by us: For, having first ​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 substracted, 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.
1. 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 ​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 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 by 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.
​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 the 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 abhorrence 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 assusted 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; an Art deserving great Elogiums, not only, upon the account of its 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 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. Nicolas 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; 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 Sanguifcation, 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.
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 ​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 Conglobate,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 ether 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 Ganduls, &c. 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 Glanduls: And then, that Glanduls are a kind of Strainer; 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 heat 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’ or Skates, and relates that the Author found in the bellies of these Fishes a Haddock of 1⁠1/2⁠ 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: asserting, 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 ​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 fœtus; 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. Regenri 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 conflax 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 Mebius 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 experiment, either to confirm what this Author has started, if true, or to rectifie it, if he be mistaken.
In Fig. 1. of Num. 9 of these Tracts, the Graver hath placed the bended end of the sprinting Wire, CF, 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.