OBSERVATIONS

Made this 27th.[35]

of _October_ 1663. about

Mr. _Clayton's_

Diamond.[36]

Being look'd on in the Day time, though in a Bed, whose Curtains were

carefully drawn, I could not discern it to Shine at all, though well

Rubb'd, but about a little after Sun-set, whilst the Twilight yet lasted,

Nay, this Morning[37] a pretty while after Sun-rising, (but before I had

been abroad in the more freely inlightned Air of the Chamber) I could upon

a light Affriction easily perceive the Stone to Shine.

[35] These were brought in and Read before the Royal Society, (the Day

following) _Oct._ 28. 1663.

[36] _The Stone it self being to be shown to the Royal Society, when the

Observations were deliver'd, I was willing (being in haste) to omit the

Description of it, which is in short, That it was a Flat or Table

Diamond, of about a third part of an Inch in length, and somewhat less in

breadth, that it was a Dull Stone, and of a very bad Water, having in the

Day time very little of the Vividness of ev'n ordinary Diamonds, and

being Blemished with a whitish Cloud about the middle of it, which

covered near a third part of the Stone._

[37] _Hast made me forget to take notice that I went abroad the same

Morning, the Sun shining forth clear enough, to look upon the Diamond

though a_ Microscope, _that I might try whether by that Magnifying Glass

any thing of peculiar could be discern'd in the Texture of the Stone, and

especially of the whitish Cloud that possest a good part of it. But for

all my attention I could not discover any peculiarity worth mentioning._

Secondly, The Candles being removed, I could not in a Dark place discern

the Stone to have any Light, when I looked on it, without having Rubb'd or

otherwise prepar'd it.

Thirdly, By two white Pibbles though hard Rubb'd one against another, nor

by the long and vehement Affriction of Rock Crystal against a piece of Red

cloath, nor yet by Rubbing two Diamonds set in Ring, as I had Rubb'd this

Stone, I could produce any sensible degree of Light.

Fourthly, I found this Diamond hard enough, not only to enable me to write

readily with it upon Glass, but to Grave on Rock Crystal it self.

Fifthly, I found this to have like other Diamonds, an Electrical

faculty.[38]

[38] V. _For it drew light Bodies like Amber, Jet, and other Concretes

that are noted to do so; But its attractive power seem'd inferiour to

theirs._

Sixthly, Being rubb'd upon my Cloaths, as is usual for the exciting of

Amber, Wax, and other Electrical Bodies, it did in the Dark manifestly

shine like Rotten Wood, or the Scales of Whitings, or other putrified Fish.

Seventhly, But this Conspicuousness was Fainter than that of the Scales,

and Slabber (if I may so call it) of Whitings, and much Fainter than the

Light of a Glow-worm, by which I have been sometimes able to Read a short

Word, whereas after an ordinary Affriction of this Diamond I was not able

to discern distinctly by the Light of it any of the nearest Bodies: And

this Glimmering also did very manifestly and considerably Decay presently

upon the ceasing of the Affriction, though the Stone continued Visible some

while after.

Eighthly, But if it were Rubb'd upon a convenient Body for a pretty while,

and Briskly enough, I found the Light would be for some moments much more

considerable, almost like the Light of a Glow-worm, insomuch after I ceased

Rubbing, I could with the Chaf'd stone exhibit a little Luminous Circle,

like that, but not so bright as that which Children make by moving a stick

Fir'd at the end, and in this case it would continue Visible about seven or

eight times as long as I had been in Rubbing it.

Ninthly, I found that holding it a while near[39] the Flame of a Candle,

(from which yet I was carefull to avert my Eyes) and being immediately

remov'd into the Dark, it disclosed some faint Glimmering, but inferiour to

that, it was wont to acquire by Rubbing. And afterward holding it near a

Fire that had but little Flame, I found the Stone to be rather less than

more excited, than it had been by the Candle.

[39] IX. _We durst not hold it in the Flame of a Candle, no more than put

it into a naked Fire; For fear too Violent a Heat (which has been

observ'd to spoil many other precious Stones) should vitiate and impair a

Jewel, that was but borrow'd, and was suppos'd to be the only one of its

Kind._

Tenthly, I likewise indeavour'd to make it Shine, by holding it a pretty

while in a very Dark place, over a thick piece of Iron, that was well

Heated, but not to that Degree as to be Visibly so. And though at length I

found, that by this way also, the Stone acquired some Glimmering, yet it

was less than by either of the other ways above mention'd.

Eleventhly, I also brought it to some kind of Glimmering Light, by taking

it into Bed with me, and holding it a good while upon a warm part of my

Naked Body.

Twelfthly, To satisfie my self, whether the Motion introduc'd into the

Stone did generate the Light upon the account of its producing Heat there,

I held it near the Flame of a Candle, till it was qualify'd to shine pretty

well in the Dark, and then immediately I apply'd a slender Hair to try

whether it would attract it, but found not that it did so; though if it

were made to shine by Rubbing, it was as I formerly noted Electrical. And

for further Confirmation, though I once purposedly kept it so near the hot

Iron I just now mention'd, as to make it sensibly Warm, yet it shin'd more

Dimly than it had done by Affriction or the Flame of a Candle, though by

both those ways it had not acquir'd any warmth that was sensible.

Thirteenthly, Having purposely rubb'd it upon several Bodies differing as

to Colour, and as to Texture, there seem'd to be some little Disparity in

the excitation (if I may so call it) of Light. Upon White and Red Cloths it

seem'd to succeed best, especially in comparison of Black ones.

Fourteenthly, But to try what it would do rubb'd upon Bodies more hard, and

less apt to yield Heat upon a light Affriction, than Cloath, I first rubb'd

it upon a white wooden Box, by which it was excited, and afterwards upon a

piece of purely Glazed Earth, which seem'd during the Attrition to make it

Shine better than any of the other Bodies had done, without excepting the

White ones, which I add, lest the Effect should be wholly ascrib'd to the

disposition White Bodies are wont to have to Reflect much Light.

Fifteenthly, Having well excited the Stone, I nimbly plung'd it under

Water[40], that I had provided for that purpose, and perceiv'd it to Shine

whilst it was beneath the Surface of that Liquor, and this I did divers

times. But when I indeavour'd to produce a Light by rubbing it upon the

lately mentioned Cover of the Box, the Stone and it being both held beneath

the Surface of the Water, I did not well satisfie my self in the Event of

the Trial; But this I found, if I took the Stone out, and Rubb'd it upon a

piece of Cloath, it would not as else it was wont to do, presently acquire

a Luminousness, but needed to be rubb'd manifestly much longer before the

desired Effect was found.

[40] XV. _We likewise Plung'd it as soon as we had excited it, under

Liquors of several sorts, as Spirit of Wine, Oyl both Chymical and

express'd, an Acid Spirit, and as I remember an Alcalizate Solution, and

found not any of those various Liquors to destroy its Shining property._

Sixteenthly, I also try'd several times, that by covering it with my warm

Spittle (having no warm Water at hand) it did not lose his Light.[41]

[41] XVI. _Having found by this Observation, that a warm Liquor would not

extinguish Light in the Diamond, I thought fit to try, whether by reason

of its warmth it would not excite it, and divers times I found, that if

it were kept therein, till the Water had leisure to communicate some of

its Heat to it, it would often shine as soon as it was taken out, and

probably we should have seen it Shine more, whilst it was in the Water,

if some degree of Opacity which heated Water is wont to acquire, upon the

score of the Numerous little Bubbles generated in it, had not kept us

from discerning the Lustre of the Stone._

Seventeenthly, Finding that by Rubbing the Stone with the Flat side

downwards, I did by reason of the Opacity of the Ring; and the sudden Decay

of Light upon the ceasing of the Attrition, probably lose the sight of the

Stones greatest Vividness; and supposing that the Commotion made in one

part of the stone will be easily propagated all over, I sometimes held the

piece of Cloath upon which I rubb'd it, so, that one side of the Stone was

exposed to my Eye, whilst I was rubbing the other, whereby it appear'd more

Vivid than formerly, and to make Luminous Tracts by its Motions too and

fro. And sometimes holding the Stone upwards, I rubb'd its Broad side with

a fine smooth piece of Transparent Horn, by which means the Light through

that Diaphanous Substance, did whilst I was actually rubbing the Stone,

appear so Brisk that sometimes and in some places it seem'd to have little

Sparks of fire.

Eighteenthly, I took also a piece of flat Blew Glass, and having rubb'd the

Diamond well upon a Cloath, and nimbly clapt the Glass upon it, to try

whether in case the Light could peirce it, it would by appearing Green, or

of some other Colour than Blew, assist me to guess whether it self were

sincere or no. But finding the Glass impervious to so faint a Light, I then

thought it fit to try whether that hard Bodies would not by Attrition

increase the Diamonds Light so as to become penetrable thereby, and

accordingly when I rubb'd the Glass briskly upon the Stone, I found the

Light to be Conspicuous enough, and somewhat Dy'd in its passage, but found

it not easie to give a Name to the Colour it exhibited.

Lastly, To comply with the Suspition I had upon the whole Matter, that the

chief manifest Change wrought in the Stone, was by Compression of its

parts, rather than Incalescence, I took a piece of white Tile well Glaz'd,

and if I press'd the Stone hard against it, it seem'd though I did not rub

it to and fro, to shine at the Sides: And however it did both very

manifestly and vigorously Shine, if whilst I so press'd it, I mov'd it any

way upon the Surface of the Tile, though I did not make it draw a Line of

above a quarter of an Inch long, or thereabouts. And though I made it not

move to and fro, but only from one end of the short Line to the other,

without any return or Lateral motion. Nay, after it had been often rubb'd,

and suffer'd to lose its Light again, not only it seem'd more easie to be

excited than at the beginning of the Night; but if I did press hard upon it

with my Finger, at the very instant that I drew it briskly off, it would

disclose a very Vivid but exceeding short Liv'd Splendour, not to call it a

little Coruscation.[42] So that a _Cartesian_ would scarce scruple to think

he had found in this Stone no slight Confirmation of his Ingenious Masters

_Hypothesis_, touching the Generation of Light in Sublunary Bodies, not

sensibly Hot.

[42] _I after bethought my self of imploying a way, which produc'd the

desir'd Effect both sooner and better. For holding betwixt my Fingers a

Steel Bodkin, near the Lower part of it, I press'd the point hard against

the Surface of the Diamond, and much more if I struck the point against

it, the Coruscation would be extremely suddain, and very Vivid, though

very Vanishing too, and this way which commonly much surpris'd and

pleas'd the Spectators, seem'd far more proper than the other, to show

that pressure alone, if forcible enough, though it were so suddain, and

short, that it could not well be suppos'd to give the Stone any thing

near a sensible degree of Warmth, as may be suspected of Rubbing, yet

'tis sufficient to generate a very Vivid Light._

* * * * *

A Postscript.

Annexed some Hours after the Observations were Written.

_So many particulars taken notice of in one Night, may make this Stone

appear a kind of Prodigie, and the rather, because having try'd as I

formerly noted, not only a fine Artificial Crystal, and some also that is

Natural, but a Ruby and two Diamonds, I did not find that any of these

disclos'd the like Glimmering of Light;[43] yet after all, perceiving by

the Hardness, and the Testimony of a Skilfull Goldsmith, that this was

rather a Natural than Artificial Stone; for fear lest there might be some

difference in the way of Setting, or in the shape of the Diamonds I made

use of, neither of which was like this, a flat Table-stone, I thought fit

to make a farther Trial of my own Diamonds, by such a brisk and assiduous

Affriction as might make amends for the Disadvantages above-mention'd, in

case they were the cause of the unsuccessfulness of the former Attempts:

And accordingly I found, that by this way I could easily bring a Diamond I

wore on my Finger to disclose a Light, that was sensible enough, and

continued so though I cover'd it with Spittle, and us'd some other trials

about it. And this will much lessen the wonder of all the formerly

mention'd Observations, by shewing that the properties that are so strange

are not peculiar to one Diamond, but may be found in others also, and

perhaps in divers other hard and_ Diaphanous _Stones. Yet I hope that what

this Discovery takes away from the Wonder of these Observations, it will

add to the Instructiveness of them, by affording pregnants Hints, towards

the Investigation of the Nature of Light._

[43] We afterwards, try'd precious Stones, as Diamonds, Rubies, Saphires,

and Emeralls, &c. but found not any of them to Shine except some

Diamonds, and of these we were not upon so little practice, able to

fore-tell before hand, which would be brought to Shine, and which would

not; For several very good Diamonds, either would not Shine at all, or

much less than others that were farr inferiour to them. And yet those

Ingenious Men are mistaken, that think a Diamond must be foul and cloudy,

as Mr. _Claytons_ was, to be fit for Shining; for as we could bring some

such to afford a Glimmering Light, so with some clear and excellent

Diamonds, we could do the like. But none of those many that we try'd of

all Kinds, were equal to the Diamond on which the Observations were made,

not only considering the degree of Light it afforded, but the easiness

wherewith it was excited, and the Comparatively great duration of its

Shining.