Electricity of High-Pressure Steam. 377 



returned much surprised at the phenomena it presented. The 

 singular circumstance of a steam-boiler yielding electrical 

 sparks, and giving shocks, now began to be noised abroad ; 

 and my friend, Mr. Henry Smith, of Newcastle, who had 

 heard the account both from Mr. Golightly and Mr. Marshall, 

 wrote me a note acquainting me with the matter, and desiring 

 me to go with him to see it, which I did on the 11th inst., and 

 again on the following day, having with us the second time 

 proper electrical apparatus. On our first visit, the boilers 

 being unplugged and empty, we merely satisfied ourselves as 

 to all the particulars of their setting, etc., already detailed. 

 Next day, on our arrival, we found the engine at work, the 

 steam up to a pressure of thirty-five pounds an inch, and blow- 

 ing off strongly at the joint in the boiler. The day was a little 

 damp, but yet not unfavourable, and we were informed on 

 alighting that the indications of electricity were very faint and 

 weiik ; however, we proceeded to our examination, of which 

 the following is the result. 



1 . On touching the boiler with the blunt point of a pen- 

 knife anywhere about the circular end, the weight or the safety- 

 valve itself, with the steam strongly blowing out of the joint, 

 but with no part of the person exposed to the volume of steam, 

 no spark could be perceived whatever. 



2. On immersing one hand in the current of steam, and 

 touching the parts of the boiler already named with the point 

 of a penknife held in the other, a very minute but distinct 

 spark was perceived, and this occurred equally on all parts of 

 the boiler, or safety-valve, within reach. 



3. By standing in the current of steam, so as to allow it to 

 blow forcibly upon the person, the spark became larger; it 

 was then one-eighth of an inch long. 



4. On holding a large shovel in the current of steam with 

 one hand, and touching the boiler with a penknife held in the 

 other, a spark was obtained three-eighths of an inch long. 



5. The cap of a gold-leaf electrometer, the bottom of 

 which was held in the hand, was applied to the weight, the 

 body of the operator being entirely out of the current of steam; 

 and no divergence was produced whatever. 



6. The electrometer held in the hand had its cap applied 

 to the weight, the other hand of the operator being immersed 

 in the current of steam : strong divergence was immediately 

 produced. 



From this it was evident that the electricity proceeded from 

 the steam ; but as the boiler-house was damp, so that insulation 

 by glass could not well be preserved, a copper wire was at- 

 tached to the shovel already mentioned, the end of which wire 

 terminated in the engine-house, some yards distant from the 



