Proceedings of the Polytechnic Association. 1007 



imported from tlie other hemisphere, it is certain that, without the 

 co-operation of the three first named conditions, neither it nor any 

 other fungus can be propagated, to the injury of individual or public 

 health. Hence, whatever contributes to the prompt removal, from 

 this or any other city, of the decomposable organic matter, the 

 surplus water or moisture, and gives to all its inhabitants air and 

 sunlight, contributes directly to the public health. 



Improved Fuenace. 



Mr. Jonathan Amory, of Boston, exhibited a model of a furnace. 

 He said it had been extensively applied in the smelting of ores in 

 California, Nevada, Montana, etc. Fairbairn and other engineers of 

 equal reputation, have given certificates of a saving of thirty-seven 

 per cent over the best results before attained. A slow combustion is 

 kept up in one chamber, from which the carbonic oxyd .is taken to 

 another chamber, where, between reverberating plates, it meets with 

 currents of hot air, when it is at once converted to carbonic acid, 

 generating at the same time an intense heat. This is the chamber 

 of quick combustion ; from here the highly heated gases are con- 

 ducted along the surfaces that are to absorb the heat. By this means 

 all the combustible gases are burned, and none are left to take fire at 

 the top of the chimney. In steamers the air may be taken from the 

 deck, and the furnaces so arranged that the fires may burn well when 

 the water was up to the grate bars ; a great advantage in case of 

 springing a leak at sea. These furnaces are also in use on some eight 

 locomotives. A church holding twelve hundred persons had been 

 warmed by only two of these furnaces. 



Mr. Robert Weir asked if the great heat would not burn out the 

 curv^es or iron bridges. 



Mr. Amory replied that he did not find it so ; he makes the curves 

 so that they will last as long as the boiler. Thirteen years ago he 

 applied this furnace to some eight locomotives, and by it we were the 

 first to use our coal on locomotives in this country. 



Improved Steam-boiler. 



Mr. McGinnis showed a model of his vertical boiler. He proposed 

 to use a number of them on board of steamships, and carry steam of 

 very higli ])ressure. 



Mr. J. B. Eoot said that the more this boiler approached to the 



