456 PHILOSOPHICAL TRANSACTIONS. [aNNO 1773. 



ately opposite to him ; and every one was persuaded that the greatest explosion 

 had been directly before himself. Hearing however a voice saying, un fulmine, 

 un fulmine ! they began to examine the gallery in which they were, and soon 

 discovered that the gilding of the cornish had been affected, for in the corners, 

 and at every junction, it was quite blackened; those that had been sitting under 

 the Cornishes were covered with the shining particles of the varnish that went 

 over the gilding, and which was thrown off in small dust, at the moment of the 

 explosion. In the apartment above, the same operation had been performed on 

 the gildings; and it is certain that the profusion of gildings, and the bell-wires, 

 prevented the lightning from making more use of the company to conduct it in 

 its course. For further particulars, see Sir Wm. Hamilton's Essays collected. 



XXXV. On some' Improvements in the Electrical Machine. By Dr. Nooth. p. 333. 



It is evident, that the electric matter is excited in the instant that the glass 

 passes over the rubber, and that it becomes sensible to us by its adhering to the 

 revolving surface of the glass. It also appeared highly probable, that the quan- 

 tity of fire, which we find on the glass in motion, is not the whole of that which 

 is excited by the passage of the glass on the rubber. The luminous appearance 

 in the angles between the glass and rubber, and which is extremely distinct in a 

 dark room, rendered it next to certain, that a part of the excited electric fluid 

 returns immediately to the cushion without performing a revolution with the 

 glass; and that of course a circulation of the fire is thus kept up in the substance 

 of the cushion in the common method of constructing the machines. 



To be convinced of this. Dr. N. attempted to make the passage of the fire 

 from the glass to the anterior part of the cushion, or to that part which cor- 

 responds with the ascending side of the cylinder, demonstrable, by placing a 

 piece of silk between the glass and cushion. This silk was larger than the 

 cushion ; and part of it was allowed to adhere, by the attraction of the electric 

 fire, to the ascending part of the cylinder. His view in doing this was to cut 

 off, in that part, the immediate communication between the excited glass and 

 cushion, and by that ineans render the circulation of electric matter visible, 

 which he suspected to take place in the machine; as it was thus forced to turn 

 over the loose edge of the silk before it could return to the cushion. The event 

 answered his expectation ; and he then perceived, that the greatest part of the 

 excited fluid was commonlv re-absorbed by the fore part of the cushion without 

 becoming sensible on the superior part of the glass. 



Having thus verified his supposition by actual experiments with silken flaps of 

 difFerent sizes, he endeavoured to discover a method of preventing that circula- 

 tion of the electric fluid, and if possible, of obliging the whole, or the greater 

 part of itj that is once excited, to make the revolution with the glass. This 



