Philosophical Transactions of the Royal Society Part 23

Mr. _Oughtred_ in the VI. _Chap._ of his _Navigation_, annexed to the Book, ent.i.tuled, _The Circles of Proportion, and the Horizontal Instrument_ &c.

mentions an Artifice, by himself discover'd, by which it may be effected, that the small Parts of the _Meridian_ be not _one_ minute (which on the face of the _Earth_ answers to above an _English_ Mile) but the hundred-thousanth, or, if need be, the millioneth part of a minute, scarce exceeding one fifteenth part of an Inch: Which thing, _he saith_, he is able to perform in _Tables_ unto the _Radius_ 10000000; yet nothing at all differing either in their form or manner of working from those that are now commonly in use.

But which way this is to be done, this _Author_ hath not made known to the Publick. And, though such _Tables_ unto the _Radius_ 10000000, had been brought to light, yet would they not be sufficient to prove the ident.i.ty or sameness of the said two Lines, as to continue the comparison between them as far, as the one of them, _videl._ the _Logarithmicall Tangent-line_, is already calculated, that is; to Ten places, besides the _Charactoristick_.

Now therefore, if a certain Rule could be produced, by which the Agreement or Disagreement of the said two Lines might be shew'd, not only to that Extent of places, to which that _Tangent Line_ is already calculated, but also to as many more, as the same may be yet further extended unto, in _infinitum usque_; surely that rule would not only save us the labour of making _Tables_ unto the _Radius_ 10000000; but also the _Helix_ or Spiral Line of the Ships Course would be reduced to a more precise exactness, than ever was pretended by Him: and this most n.o.ble and Useful Science (as He justly calls it) which is the Bond of most disjunct Countries, and the Consociation of Nations farthest remote, would attain its full l.u.s.tre and perfection.

Besides, that the same Rule would also discover a far easier way of making _Logarithmes_, than ever was practised or known; and therefore might serve, when ever there should be occasion, to extend the _Logarithmes_ beyond that number of places, that is already extant.

Moreover such a rule would enable men to draw the _Meridian_ line _geometrically_, that is, without _Tables_ or _Scales_: which indeed {217} might also be done, by setting of the _Secants_ of every whole or half degree, if there were not this Inconveniency in it (which is not in my Rule:) That a Line composed of so many small parts, would be subject to many errours, especially in a small compa.s.s.

The same Rule also will serve, to find the Course and Distance between two Places a.s.signed, as far, as practice shall require it; and that, without any Table of _Meridional_ parts, and yet with as much ease and exactness.

And seeing all these things do depend on the solution of this Question, _Whether the Artificial Tangent-line be the true Meridian-line?_ It is therefore, that I undertake, by G.o.d's a.s.sistance, to resolve the said Question. And to let the world know the readiness and confidence, I have to make good this undertaking, I am willing to lay a _Wager_ against any one or more persons that have a mind to engage, for so much as _another Invention_ of mine (which is of less subtlety, but of far greater benefit to the publick) may be worth to the Inventor.

For, the great advantage, that all Merchants, Mariners, and consequently the Common-wealth, may receive from this _other Invention_, is, in my judgment, highly valuable; seeing it will oftentimes make a ship sail, though, according to the common way of sailing, the wind be quite contrary, and yet as near to the place intended, as if the wind had been favourable: Or, if you will, it will enable one to gain something in the intended way, whether the wind be good or no (except only when you go directly South or North) but the advantage will be most, where there is most need of it, that is, when the Wind is contrary: So that one may very often gain a fifth, fourth, third part, or more of the intended voyage; according as it is longer or shorter, _viz._ always more in a longer Voyage, where the gain is more considerable, and more welcome; not only by saving Time, but also Victuals, Water, Fuel, Mens health, and so much Room in the ship.

All this, which is here pretended, the Proposer is to make good by the Verdict of some able Men, who also may give a guess, what this latter Invention may be worth to the owner: And for so much, and no more, he will stand engaged against {218} any one or more Persons, that he will and shall resolve the _Question_ above-mention'd, _viz. Whether the Artificial Tangent-line be the true Meridian-line, yea or no?_ And if he do not, that then he will loose, and transport to the other Party the whole benefit of the last mentioned invention. But if, on the contrary, he do prove or disprove the Ident.i.ty of the said two lines, to the Judgment of some able _Mathematicians_, That then so much money be paid him by the other Party, as the said Invention was valued.

And, whereas there are often Wagers laid about things that concern the Engagers little or nothing; 'tis thought, that it would concern all Merchants, Mariners, and all Lovers of the common good, rather to lay wagers against one another about Things of this nature, where the Gainer doth gain as well, as if he had laid his wager about something else, and the Looser hath so far the benefit as well as the Gaine, That he seeth thereby promoted the thing, that concerns them both alike.

Now therefore, to the end, that the Looser may have his benefit by it, as well as the Gainer, it would not be amiss, that the condition were made thus, that the latter should grant the moity of his gain to the Proposer; that thereby he might be enabled to bring to light both those, and some other useful inventions, for the Service of Mankind. And to manifest, that it is not for his own interest only, that the _Proposer_ mentions this; he is willing to impart from that moity, so received, the full moity again to any other person within his Majesty's Dominions, who shall first of all give notice of his Undertaking to prove or disprove the said Ident.i.ty, and perform it accordingly within the s.p.a.ce of two Months, to be computed from the present Date. Those that have a mind to engage, may repair to the Printers of these _Tracts_, where they may know further.

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_A new Contrivance of _Wheel-Barometer_, much more easy to be prepared, than that, which is described in the _Micrography_; imparted by the Author of that Book._

This is only an easy way of applying an _Index_ to any _Common Barascope_, whether the Gla.s.s be only a Single Cane, or have a round Bolthead at the top. And by the means thereof, the {219} Variation of the Alt.i.tude of the _Mercurial_ Cylinder, which at most is hardly three Inches, may be made as distinguishable, as if it were three Foot, or three Yards, or as much more, as is desired.

The manner hereof is visible enough by _Figure_ I: where A B C represents the Tube, which may be either Blunt, or with a Head, as A B C (by which latter shape, more room is allow'd for any remainder of Air, to expand the better.) This is to be filled with Quick-silver, and inverted as commonly; but into a Vessel of Stagnant Mercury, made after the fashion of I K, that is, having its sides about 3 or 4 inches high, and the Cavity of it equally big both above and below; and if it can be (besides that part, which is fill'd by the end of the _Mercurial_ Tube, that stands in it) of equal capacity with the hollow of the Cane about B: For then the Quicksilver rising as much in the hollow of I, as it descends at B, the difference of the height in the Receiver I, will be just half the usual difference, And if the receiving Vessel I K have a bigger Cavity, the difference will be less, but if less, the difference will be greater: But, whether the difference be hereby made bigger or less, 'tis no great matter, since by the contrivance of the _Wheel_ and _Index_ (which is more fully described in the _Preface_ to the _Micrography_) the least variation may be made as sensible as is desired, by diminishing the bigness of the Cylinder E, and lengthening the _Index_ F G, according to the Proportion requisite.

_An Account of _Four Suns_, which very lately appear'd in _France_, and of two _Raine-bows_, unusually posited, seen in the same Kingdom, somewhat longer agoe._

These _Phaenomena_ are thought worthy to be inserted here, for the Speculation of the Curious in those Kingdoms; as they were publisht in the French _Journal des Scavans_, of May 10, 1666. _viz._

The 9th of _April_ of this present year, about half an hour past nine, there appear'd three Circles in the Sky. _One_ of them was very great, a little interrupted, and white every where, without {220} the mixture of any other colour. It pa.s.sed through the midst of the Sun's _Disk_, and was parallel to the _Horizon_. Its _Diameter_ was above a hundred degrees, and its _Center_ not far from the _Zenith_.

The _Second_ was much less and defective in some places, having the Colours of a Rainbow, especially in that part, which was within the great Circle.

It had the true Sun for its Center.

The _Third_ was less, than the first, but greater than the second; it was not entire, but only an Arch or Portion of a Circle, whose Center was far distant from that of the Sun, and whose circ.u.mference did, by its middle, join to that of the least Circle, intersecting the greatest Circle by its two extreams. In this Circle were discerned also the Colours of a Rainbow, but they were not so strong, as those of the _Second_.

At the place, where the circ.u.mference of this _Third_ Circle did close with that of the _Second_, there was a great brightness of Rainbow-Colours, mixt together: And at the two extremities, where this _Second_ Circle intersected the _First_, appear'd two _Parhelia's_ or Mock-suns; which shone very bright, but not so bright, nor were so well defined, as the true Sun. The False Sun, that was towards the _South_, was bigger, and far more luminous, than that towards the _East_. Besides those two _Parhelia's_, which were on the two sides of the true Sun, in the intersection of the _First_ and _Third_ Circle, there was also upon the _First_ great Circle, a _third_ Mock-sun, situated to the _North_, which was less and less bright, than the two others. So that at the same time there were seen _Four_ Suns in the Heavens.

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_Figure_ II. will ill.u.s.trate the Position of this _Phaenomenon_.

A. _The Zenith or the Point Vertical to the place of Observation._

B. _The true Sun._

S C H N. _The great Circle, altogether White, almost parallel to the Horizon, which pa.s.s'd through the true Sun's Diske, and upon which were the false Suns._

D E B O. _A Rain-bow about the Sun, forming an entire Circle, but interrupted in some places._

H D N. _A portion of a Circle, that was Excentrick to the Sun, and greater than the Circle_ D E B O, _which touch'd_ D E B O, _and was confounded with it in the point_ D. {221} H N. _The two Mock-Suns, in the intersection of the Semicircle_ H D N, _and the Circle_ S C H N: _The midst of which two False-Suns was white and very luminous; and their Extremities towards_ D I _were tinged with the Colours of a Rainbow. The False Sun, mark'd_ N, _ was fainter than that, which is mark'd_ H.

C. _The Mock-Sun, all white, and far less shining, than the two others._

I. _A s.p.a.ce very dark betwixt_ R. _and_ D.

[Sidenote: * _Those _Five_ Suns, that appear'd the 29 _March_, A. 1629. at _Rome_, between 2 or 3 of the Clock, in the afternoon, were thus posited; that the two of them, which were in the intersection of two Circles, appear'd in that of a Circle, which pa.s.sed through the Sun's Diske, with another, that was _Concentrick_ to the Sun: as may be seen in _Figure III_.

borrow'd (for the easier comparing them together) out of _Des-Cartes_ his _Meteors_, cap. X._]

This Appearance is look't upon as one of the notablest, that can be seen, by reason of the _Excentricity_ of the Circle H D N, and because that the _Parhelia_ * were not in the Intersection of the Circle D E B O with the great Circle S C H N, but in that of the Semi-circle H D N.

As for the two odd _Rainbows_; they appear'd at _Chartres_ the 10. of _August_, 1665. about half an hour past six in the Evening; and did cross one another almost at right Angles, as may be seen by _Fig._ IV.

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The Rainbow, which was opposite to the Sun, in the usual manner, was more deeply colour'd, than that, which cross'd it; though even the Colours of the first _Iris_ were not so strong, as they are now and then seen at other times.

The greatest height of the stronger Rainbow, was about 45. degrees; the feebler Rainbow lost one of its Legs, by growing fainter, about 20 degrees above the stronger; and the Leg below appear'd continued to the _Horizon_.

These Rainbows did not _Just_ decussate one another at right Angles; there was some 6 or 7 degrees difference. The fainter, seem'd to be a Portion of a great Circle; and the stronger was but a Portion of a small Circle, as usually.

The Sun, at their appearance, was about 6 degrees high above the _Horizon_, and towards the 17 _Azimuth_ of the West, Northward.

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The Observer, M. _Estienne_, notes, that, when he made this Observation, the River of _Chartres_, which runs very near from _South_ to _North_, was betwixt him and the Rainbow; and that he stood Level with this River, whence he was distant not above 150 paces: which he adds, that the Curious may the better judge of this Observation.

_A Relation of an Accident by Thunder and Lightning, at _Oxford_._

This was imparted by Dr. _Wallis_ in a Letter, written at _Oxford_, May 12, 1666. to the _Publisher_, as follows:

I should scarce have given you so soon the trouble of another Letter, were it not for an Accident which hapn'd here _May_ 10. I had that afternoon, about 4 of the clock heard it thunder at some distance. About 5 of the clock the Thunder coming nearer to us; it began to rain, and soon after (the rain withal increasing) the Thunder grew very loud, and frequent, and with long ratling Claps (though not altogether so great, as I have some other times heard:) and the Lightning with flashes very bright (notwithstanding the clear day-light) and very frequent, (when at the fastest, scarce a full minute between one flash and another; many times not so much, but a second flash before the Thunder of the former was heard:) The Thunder for the most part began to be heard about 8 or 10 second minutes after the flash; as I observ'd for a great part of the time by my Minute-Watch: but once or twice I observ'd it to follow (in a manner) immediately upon it, as it were in the same moment; and the lightning extream red and fiery. I do not use to be much apprehensive of Thunder and Lightning, but I was at this time (I know not well, why?) very apprehensive, more than ordinary, of mischief to be done by it, for it seem'd to me to be very low and near us (which made me so particular, as to observe the distance of the flash by the noise) and very frequent, and bright, so that, had it been by night as it was by day, it would have been very terrible. And, though I kept within doors, yet I sensibly discover'd a stinking sulphureous smell in the Air. About 7 of the clock it ended, before which time I had news brought me of a Sad Accident upon the {223} water at _Medley_ about a Mile or somewhat more distant from hence. Two Schollars of _Wadham_-Colledge, being alone in a Boat (without a Water-man) having newly thrust off from sh.o.r.e, at _Medley_, to come homewards, standing near the Head of the Boat, were presently with a stroke of Thunder or Lightning, both struck off out of the Boat into the Water, the one of them stark dead, in whom, though presently taken out of the Water (having been by relation, scarce a minute in it) there was not discerned any appearance of life, sense, or motion: the other was stuck fast in the Mud (with his Feet downwards, and his upper parts above water) like a post not able to help himself out; but, besides a present stonying or numness, had no other hurt; but was for the present so disturb'd in his senses, as that he knew not, how he came there out of the Boat, nor could remember either Thunder or Lightning, that did effect it: and was very feeble and faint upon it; which (though presently put into a warm Bed) he had not thoroughly recover'd by the next Night; and whether since he have or no, I know not.

Others in another Boat, about 10 or 20 yards from these (as by their description I estimate) felt a disturbance and shaking in their Boat, and one of them had his Chair struck from under him, and thrown upon him; but had no hurt. Those immediately made up to the others, and (some leaping into the Water to them) presently drew them either into the Boat or on Sh.o.r.e; yet none of them saw these two fall into the Water (not looking that way) but heard one of them cry out for help presently upon the stroke, and smelt a strange stinking smell in the Air; which, when I asked him, that told it me, what kind of stink? he said, like such a smell, as is perceived upon the stricking of Flints together.

He that was dead (when by putting into a warm Bed, and rubbing, and putting strong waters into his Mouth, &c. no life could be brought into him) was the next morning brought to town; where, among the mult.i.tudes of others, who came to see, Dr. _Willis_, Dr. _Mellington_, Dr. _Lower_, and my self, with some others, went to view the Corps: where we found no wound at all in the skin, the face and neck swart and black, but not more, than might be ordinary, by the settling of the blood: On the right side of the neck was a little blackish spot about an inch long, and {224} about a quarter of an inch broad at the broadest, and was, as if it had been sear'd with a hot iron; and, as I remember, one somewhat bigger on the left side of the neck, below the Ear. Streight down the breast, but towards the left side of it, was a large place about three quarters of a Foot in length, and about two inches in breadth, in some places more, in some less, which was burnt and hard, like Leather burnt with the fire, of a deep blackish red Colour, not much unlike the scorch'd skin of a rosted Pig. And on the fore-part of the left Shoulder such another spot about as big as a Shilling; but that in the neck was blacker and seem'd more sear'd. From the top of the right shoulder, sloping downwards towards that place in his Breast, was a narrow Line of the like scorched skin; as if somewhat had come in there at the neck, and had run down to the breast, and there spread broader.