( 21 7Z ) 
At another time I made ufe of t\f o flat Shells of Oyfters 
well dry'd $ inftead of the Woollen for the Attrition of 
the Glaft, each Arm of the Brafs Spring had one fixt to it. 
Upon the ufual Motion given the Glafs in Vacuo^ a Light 
appeared, rcfembling a fierce flaming Spark, juft upon the 
fpot where the Glafs and Shells toucht one upon another. 
The Light feenVd not to extend itfelf, but was comprc- 
htndcd inafmall Compafs. 
I try'd next what would enfue upon the Attritioaof 
Woollen on the prementiond Shells in Vacuo. Thefuccefs 
tvas, that there was a Light produced, but appeared very 
dim and gloomy, at beft like a faint Hdo. 
After all thcfe, I thought it not amifs, to try in what 
degree the Woollen might contribute to the Ph£nomcna of 
the foregoing Expenments. I took fome of the Lift former* 
ly mentioned, and bound it about the edge of a Wooden 
Wheel i had caus'd to be Turnd for that purpofe , the 
Wheel, with its Woollen edge, 1 faften d on the Spindle, 
as ufual, and upon the Brafs Spring was ufed the fame Gar- 
tering, as in the firft Experiment. Thefe being put toge- 
ther, as in all the others, and the Receiver exhaufted, 
the large Wheel wasturn'd, and upon the Attrition of the 
Woollens, a fmall glimmering Light did fucceed 5 but the 
Continuance of the Motion, gave no encouragement to 
hope for any increafeof it. lexpefted to have found the 
Woolleos at leaft difcolour'd, upon the Friftion of them, 
which was fometimes made more than moderate. On the 
contrary, not the leaft Sign of any fuch thing appeared. 
The Light totally difappear'd, upon the rcadmiffion of lefs 
than a quarter of the Recipients natural Content of Air, 
altho the Attrition then made v/as as great as it had been 
at any time before* I cannot dilcover that the various 
Colours of Woollen ( as yet that I have try'd) does any 
thing contribute to the Different Colours of Light, exhi- 
bited in any of thefc Experiments; 
Expe- 
