of a Jet of Steam issuing from a Boiler. .371 



boiler and safety-valve, by which it will be seen that the valve 

 is placed on the top of a small cylinder, having a flange round 

 the lower end, which is fastened by bolts to the summit of the 

 boiler, between which and the flange, a cement, composed of 

 chalk, oil and tow, is interposed for the purpose of making 

 the joining steam-tight. 



About three weeks ago the steam began to escape at this 

 joining, through a fissure in the cement, and has ever since 

 continued to issue from the aperture in a copious horizontal 

 jet. Soon after this took place, the engine-man, having one 

 of his hands accidentally immersed in the issuing steam, 

 presented the other to the lever of the valve, with the view of 

 adjusting the weight, when he was greatly surprised by the 

 appearance of a brilliant spark, which passed between the 

 lever and his hand, and was accompanied by a violent wrench 

 in his arms, wholly unlike what he had ever experienced be- 

 fore. The same effect was repeated when he attempted to 

 touch any part of the boiler, or any iron-work connected with 

 it, provided his other hand was exposed to the steam. He next 

 found that while he held one hand in the jet of steam, he com- 

 municated a shock to every person whom he touched with the 

 other, whether such person were in contact with the boiler, 

 or merely standing on the brick-work which supports it; but 

 that a person touching the boiler, received a much stronger 

 shock than one who merely stood on the bricks. 



These singular effects were witnessed and experienced by 

 a great many persons, and among others by two gentlemen 

 with whom I am personally acquainted, and who fully corro- 

 borate the above account, which I obtained from the engine- 

 man. 



The boiler had been cleaned out the day before I saw it, 

 and a thin incrustation of calcareous matter reaching as high 

 as the water level had been removed, and the consequence 

 was, that the indications of electricity, though still existing, 

 were very much diminished. Still, however, what remained 

 was very extraordinary ; for when I placed one hand in the 

 jet of steam and advanced the other within a small distance 

 of the boiler, a distinct spark appeared, and was attended 

 with a slight electrical shock. 



From the effect produced by the cleaning of the boiler, it 

 appears pretty obvious that the phaenomenon is in a great 

 measure, though not wholly, dependent upon the existence of 

 an incrustation within ; and the reason why such effects do 

 not in any degree attend the effluxion of a jet of steam from 

 a boiler in ordinary cases, must, I apprehend, be sought for 

 in the fact, that in the present instance the steam escapes 



2 B2 



