METHODS TO CYLINDRICAL RETURN TUBULAR BOILERS. 173 



three furnaces, and it has a tremendous number of 3^ tubes and does not have any of these 

 large spaces which have been referred to. However, these diagrams I do not thini< can, be 

 affected very much by the adoption of this practice, provided you do not make the space too 

 great, because by spreading these tubes slightly above the center of the furnace, it would 

 merely mean the elimination of three or four tubes on the circumference of the boiler, which 

 could readily be taken care of in estimating your heating surface from the diagrains. Per- 

 sonally, I think it is a good thing to do. 



Mr. Edward C. Gillette, Member (Communicated): — The subject has been ably han- 

 dled by Mr. Meyer and covers a number of points which have not heretofore appeared clearly 

 in print, and which are of invaluable assistance to the designer in cutting corners and check- 

 ing his work. 



I have no comments to make except that, as the shipping world is now resorting to oil 

 as fuel, it would appear that additions to your present data covering oil-burning boilers would 

 be very interesting and advantageous. In this connection it appears, from my experience, 

 that the question of added heating surface in furnaces with the omission of grate bars, etc., 

 the use of separate vs. one combustion chamber common to all furnaces ; size of tubes or the 

 use of retarders in boilers converted from coal to oil fuel, and the size of stacks and heights 

 of same, etc., should be given some consideration. 



With reference to the use of one combustion chamber common to all furnaces vs. sepa- 

 rate chambers, there are advantages and disadvantages in both, but it is thought that a 

 boiler fitted for burning oil, when under "banked fires," i. e., one burner in operation, the 

 one common chamber is preferable in that tlie heat is more evenly distributed, tending to 

 equalize in the chamber and all furnaces, thus eliminating expansion and contraction strains, 

 which would be more pronounced with separate chambers. 



The President : — Commander Stevenson Taylor expressed the opinion of the Chair 

 with reference to Mr. Meyer's paper. It is a record of interesting and valuable data, and I 

 am sure you will permit the Chair to extend the Society's thanks to Mr. Meyer for his pains- 

 taking care in the preparation of this paper and its presentation. 



The next paper is entitled "New Developments in High Vacuum Apparatus," by Mr. G. 

 L. Kothny, Member. 



Mr. Kothny presented the paper. 



