716 Transactions of the American Institute. 



inventor put a copper plate in the boiler, so that the scale should 

 form on this plate instead of on the iron shell ; but it made such 

 galvanic action that the boiler corroded at a fearful rate. I have put 

 steel points in a boiler, but the result was negative. 



Mr. Hudson — It would be reasonable to infer from the argument 

 that the electricity developed in a boiler is part of its working power ; 

 so that withdrawing that electricity by lightning rods, or otherwise, 

 takes away part of the power. 



Dr. D. D. Parmelee — It would be easy to attach a galvanometer 

 to an insulated rod inside of a boiler and test it. If we can get a 

 spark in that way, we shall have something to work upon. 



Dr. P. H. Van der Weyde — I thank the gentlemen for the sugges- 

 tion. I have now in Philadelphia four or five boilers in which that 

 can be easily tried. If there is electricity there the galvanometer 

 will show it. 



The President — The boiler might be entirely insulated, and then 

 if any quantity of electricity is generated it must escape through the 

 wire and manifest itself. 



Dr. P. H. Van der Weyde — The theory that the gases are ignited 

 by electricity is absurd. The presence of the gases in the boiler can 

 be easily tested. We have only to draw steam, and see if it will all 

 condense into water. There may be a little air mixed with it; but 

 if. there should be an explosive mixture left after condensation, it 

 would settle that question. 



Professor R. H. Thurston — I understand that Judge Hayes bases 

 his whole argument upon the supposition that the pressure of steam 

 could not cause the destructive violence witnessed in explosions. 

 The report lying on your table, to the Secretary of the Navy, written 

 by Mr. Isherwood, will sufficiently show whether that supposition is 

 correct. 



Professor E,. H. Thurston then read the following report : 



New York, December 12th, 1871. 



Sir. — Agreeably to your orders of the 18th ultimo, appointing the 

 undersigned a board to witness, report upon, and give all necessary 

 information relating to the experiments being made at Sandy Hook, 

 New York, by Mr. Francis B. Stevens, of Hoboken, New Jersey, on 

 steam boiler explosions, we have the honor to submit a description of 

 them as far as they have progressed, accompanied by our observations 

 on their results 



The experiments referred to were devised by Mr. Stevens in pursu- 



