L 373 ] 
rod, or with the brafs cap at the upper extremity of 
that tube, and the other end of the wire fattened to 
any part of the frame of the electrifying machine, 
and this laft put in motion, the eleCtrical corufcations 
are feen to pafs as before from one of the brafs 
plates contained in the tube to the other • and to con- 
tinue, unlefs the air infinuates itfelf, as long as the 
machine is in motion. If, under thefe circumftances, 
the hand of a perfon ftanding upon the floor is 
brought near the fides of the glafs, the corufcations 
will direCt themfelves that way in great variety of 
forms, extremely curious to behold. But here, as 
in the former experiment, our vacuum did not con- 
duct fo perfectly as metals or water ; as a perfon, 
ftanding upon the floor, and applying his finger to 
the upper brafs cap of the tube, receives a fmart 
ftroke : and this I conceive to arife, from the elec- 
tricity of this brafs being fo much more rarefied, or 
attenuated, than that of the body of the man, ap- 
plying his finger. 
This experiment fhould be made in the middle 
of a large room, and the machine, and man turn- 
ing it, fhould be raifed from the floor at leaft a foot : 
©therwife the effeCts defired will be diminifhed by 
the eleClricity being in part furnifhed by the floor to 
the machine. 
To what is here laid down it may be objected, 
that the eleCtrical corufcations in the laft experiment 
proceed, not from the floor of the room, as I have 
conjectured, but from the electricity being, from the 
globe in motion, diffufed at the fame time upon 
the prime conductor, as well as all over the machine,, 
and which in the tube becomes vilible in its paflage 
4 to 
