Proceedings of ihe Polytechnic Association. 1067 



constructed ones this may be so ; but that should be understood in 

 order to have ones that will do the Avork econoinicallj. A good 

 boiler should have a proper separation of water and steam, and the 

 water shonld be so arranged as to let the steam rise fully to the sur- 

 &ce. In the boiler feeder here shown, everything is seen at once, 

 and it may be considered a good thing. He had seen engineers who 

 thought tliey knew so much that they would start the engine and go 

 and take a nap, and for this reason there are many intelligent engi- 

 neers who will have no device for securing safety, but trust to their 

 own care and watching. If a bridge is constructed, wg make it four 

 times as strong as the weight it will ever have to bear, and many 

 water detectors are faulty on account of not having power enough to 

 overcome any unusual circumstance that may occur, so they fail often 

 from very slight causes. 



Mr. Emery here made a drawing on the blackboard of the appara- 

 tus used by Alban, the German engineer, author of a work on the 

 high pressure steam engine. This float, by its power, he said, 

 would overcome any defects that miglit casually arise, while the hol- 

 low float would not have power to do so. 



The Chairman announced that the proceedings of this evening 

 would be the last reported in the next volume of the Transactions of 

 the American Institute, which will embrace the doings of the Poly- 

 teclmic Association from May 1st, ISGO, to May 1st, 1870. 



Adjourned. 



