( 21^9 ) 
which exhibited fparlis of Hre in a very pknttful man- 
ner After fome Air had been withdrawn, che Great 
Wheel was turned^ asbefoje, but the number of Sparks 
then producd tlul ^^ut only feera to bekfren d, but a fen- 
fible decay of their Luflxe aod Vigour was manifeft. And 
(o at every ftop that wa'^; made, to repeat the tjipcrmtm 
at greater Rarefaftions, did the Sparks producd ftili 
dimioiih in their Qiiantity and Light 5 tiii at laft^ when 
the Receiver was' well exhaufted of Air, then akho 
a more violent Motion Was given the Steel than before, 
yet not the leafl: Spark appeared to be ftruck from it: 
But a fniall Centinaed Light was vifihie on the edge of 
the FHnt, that v/m robb'd by the Steel Upon the let- 
ting in a little Air, fome Sparks upon the niotion given, 
were difcovered of a dull glopmy hue 5 but upon letting 
in a little more Air, 1 know not by what Accident, the 
whole quantity Infinuated, and then upon the repetition 
of the Wheels motion, the SpMk$ appeared nuw^iokn 
md as vivid as at firft. 
Experiment I!L 
T^Hchmg the Vrodn&wn &f a Furpie Lights tjp(m the Atintio.^- 
ofGlafs on Woollen in Vacu®* Together with the V^rhm 
Phsenomcna of the fame Experiment at fever d Tryds, As 
Ukew'jfe fome other Experiments on the fame fnhjeU^ 
The manner of making the Attrition, and the ufes of 
the feveral Apparatus^ being already at large defcrib*d, I 
(hall not need now to take farther notice of them- The 
Clafsus'd in this Experiment was Globular, about 4hiches 
Diameter, having a Pallige ihro the Middle o£ it to re- 
ceive the Spindle, to which it was faften*d with Corks 
and Screw, The Woollen againfl: w hich it was tO rub, 
wac. inch as is now commonly fold for Gartering, the 
courier fort of which Ipurpofeiy chofe for its hardmeis,' 
think- 
