372 Mr. H. G. Armstrong on the Electricity 



through an aperture in a non-conducting material, while in a 

 vast majority of cases the escape must take place through a 

 metallic orifice. Can the explosion of boilers, respecting the 

 cause of which so much uncertainty at present exists, have 

 any connexion with the rapid production of electricity which 

 thus appears to accompany the generation of steam ? 



In the present case the incrustation in the boiler is very 

 rapidly formed, and I therefore expect that in a few days the 

 effects will have become as strong as they were at first. 

 Whenever this takes place I shall again go over to witness 

 them, and if you wish for any further information, I shall 

 be glad to obtain it for you. In the mean time you are at 

 liberty to make any use of this letter that you think fit. 



I am, Sir, very respectfully yours, 

 Newcastle-upon-Tyne, Oct. 14, 1840. H. G. ARMSTRONG. 



Newcastle-upon-Tyne, Oct. 22, 1840. 



Dear Sir, — I yesterday revisited the boiler at Seghill, in 

 company with some friends, and took with me such apparatus 

 as I deemed necessary for experimenting on the electrical 

 steam. The results of this second visit I now hasten to com- 

 municate, and you will find in the following account of my 

 proceedings, answers to all the queries you were kind enough 

 to send me, for the purpose of directing my attention to the 

 proper points of inquiry. 



I found the boiler, and everything connected with it, pre- 

 cisely in the state in which I have already described it, and 

 on trying the steam in the same way as I did on the former 

 occasion, the effect was very nearly the same ; but when 

 I placed myself on an insulating stool, the intensity of the 

 sparks which passed between my hand and the boiler was 

 greatly increased, as well as the twitching sensation in the 

 knuckles and wrist, which accompanied the operation, and 

 which in my former letter I designated a slight electrical 

 shock. In pursuance of your instructions, I had provided 

 myself with a brass plate, having a copper wire attached to 

 it, which terminated in a round brass knob. When this 

 plate was held in the steam by means of an insulated handle, 

 and the brass knob brought within about a quarter of an 

 inch from the boiler, the number of sparks which passed in a 

 minute was from sixty to seventy, as nearly as we could 

 count; and when the knob was advanced about one-sixteenth 

 of an inch nearer to the boiler, the stream of electricity be- 

 came quite continuous. The greatest distance between the 

 knob and the boiler, at which a spark would pass from one to 



