OBSERVATIONS

Made this 27^th.[a]³⁵] of October 1663. about Mr. Clayton's Diamond.[a]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[a]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.

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.[a]³⁸]

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[a]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.

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[a]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.

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.[a]⁴¹]

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.[a]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.