926 Transactions of the American Institute. 



generated, and contained in the products of combustion, would pass 

 through a series of pipes inclosed with disks, and such gaseous pro- 

 ducts, after losing most of their heat, be discharged within the circle 

 of the hollow ring, upward. In this case the whole apparatus could 

 be constructed of -cast iron. 



In the several structures described, the same general features are 

 found, the novelty of which consists in furnishing very great area of 

 heating surface, at the same time securing to the fluid to be heated a 

 rapid ingress and egress. 



The Chairman invited the closest criticism of the paper just read, 

 for he was as anxious as any present to detect a fallacy in his reasoning. 



Prof. P. H. Van der Weyde — I see one advantage in the proposed 

 plan which has not been mentioned. Those who have experimented 

 with the boiling of fluids, know that there is sometimes an explosive 

 boiling. It generally occurs when the vessel in which the liquid is 

 boiled is very smooth. Sometimes sand is put in to prevent this. A 

 steam-boiler which is smooth inside, or the tubes of which are smooth, 

 is more in danger of explosive boiling than it would be if it were 

 rough or had many projecting points. It is much better to have steam 

 developed in small bubbles than in large bubbles. I think that this 

 plan will tend to prevent explosive boiling and priming in steam- 

 boilers. 



Mr. J. K. Fisher — As you have invited criticism, I will freely sug- 

 gest the doubts that arise in my mind, as to the advantages of the 

 proposed plan. In the illustrated catalogue of Morris, Tasker & Co., 

 of their tubes, instructions are given, if the water is to be outside of 

 the tubes, to reckon the outside surface of the tubes, and if the water 

 is to be on the inside, to reckon on the inside surface. That indicates 

 their opinion that the surface exposed to the water parts with its heat 

 more readily. When the tube is to be used in a heater, with steam 

 on one side and gas on the other, they act direct, taking the mean of 

 the two surfaces. That seems to me to conflict with your view, that 

 it is necessary to extend the surface exposed to water. In the 

 case of the Perkins steam-boiler, made in London, twenty-five or 

 thirty years ago, which consisted of a series of tubes, with water cir- 

 culating through them, and passing under the fire, Perkins allowed 

 2.6 feet of heating surface in the fire, to 1.6 in the water. His 

 experiments led him to adopt that as the best proportion. That also 

 indicated that it requires less surface in the water than in the fire of 

 gases. I should not regard these projections, then, as heating surface. 

 According to these authorities, the surface exposed to the water is 



