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IMPROVEMENTS in ELECTRICITY. 
TOEING appointed to deliver the annual differtation 
on fome philofophical fubjeCt, inftituted by our 
worthy brother the late Mr. henry baker, I will en- 
deavour to explain fome contrivances in electricity which 
I invented a good while ago, one of which has been 
much employed, and has undergone feveral material 
improvements fince I firft thought of it. 
IT is now about fifteen years ago fince I began to 
make ufe of flat glafles inftead of globes or cylinders, to 
excite eleCtricity. Finding that a greater quantity of 
electricity could be excited upon a flat piece of glafs, when 
rubbed on both furfaces, than when it was only expofed 
to friCtion on one fide; I thought it would be an advan- 
tage to fubftitute a round plate, or disk, of glafs, to a globe 
Vol. LXIX. 4 R or 
