VOL. XXV.] PHILOSOPHICAL TRANSACTIONS. 327 



a body brought near it seemed to be quite lost ; also the light produced on the 

 attrition of the exhausted tube, appeared wholly within it, whereas in the 

 former case it seemed to be altogether on its outside. 



I have procured also a solid tube, or rather rod, of glass, about the size of 

 the other ; and upon trial find no great difference from the other, only its effluvia 

 seemed to continue a little longer, though it attracts not at a greater distance 

 than the former. With this new tube I made the following experiment: I took 

 a little lamp-black, and having dried it on a paper before the fire, and the tube 

 being rubbed till it was warm, then being held near the lamp-black, it was 

 pleasing to behold the brisk agitation of a number of the little bodies, seeming 

 promiscuously ascending and descending with great velocity; and it was admir- 

 able to see, that bodies so light in specie, and which by their own gravity falling 

 on paper, would make no sensible noise, yet the same returned with such force 

 from the tube that their striking the paper was very audible. 



I further procured a glass nearly cylindrical, about 7 inches both in length 

 and diameter; which was put into motion by a machine of a new contrivance: 

 its axis lying parallel to the horizon, which in the like experiments before made 

 was perpendicular to it. After this cylinder was exhausted of its contained air, 

 and the motion made by the wheel, it succeeded in respect to the light pro- 

 duced on its attrition, as in the experiments before. But when all its air had 

 been readmitted, and the attrition and motion continued as at first, it was very 

 surprising to behold from the point of one's finger to the glass a strong light, 

 which began first at the finger; and seemed to gravitate on it, being sensibly 

 felt there, though the moving body was about half an inch from it. This light 

 seemed to issue from the glass with a considerable hissing noise. To try whe- 

 -ther it would exhibit any phenomenon by day light, one day in the afternoon, 

 between 2 and 3 o'clock in a very light room, I found that immediately after 

 the attrition was made on the moving glass, and the finger approached as before, 

 a pure purple light became very visible, extending from the finger to the cylinder, 

 and was accompained with the like noise as before. This experiment I have 

 repeated several times since, at different hours, and with like success, being 

 always made with a glass unexhausted of its air. To proceed. 



As to the electricity of this body on such a motion and attrition being given 

 as usual, I do not find that it exceeds in thatquality what already has been re- 

 lated in former experiments. I then took a piece of fine muslin, which was 

 sewed to two wires bent archwise, that it might surround the upper surface of 

 the glass, almost at 4 inches distance from it. I made the muslin as ragged as 

 I could, by breaking the threads of it every where; then the motion and attri- 

 tion being given, it was pleasing to see a multitude of small sparks of light 

 every where on the ends of the torn threads, which resembled so many little 



