Report of the Committee on Steam Boilers. 75 



surrounded by the heated gases. The water was maintained, during 

 the trial, just above the fourth row of tubes. 



The inventor claims that by the contraction of the passages, caused 

 by the method of connecting the tubes, the steam is disengaged from 

 the water in a comparatively dry state. 



The areas of heating and grate surfaces of tliis, and of all the boiler? 

 under consideration, are given in the table of results.* 



Description of the Allen Boiler. — (Plate 2.) 

 This boiler possesses several novel features. There are nine (9) 

 cast iron cylinders, A, A, A, etc., each seven (7) inches internal diame- 

 ter, and eleven (11) feet long; and into each of these cylinders eigh- 

 teen (18) wrought iron tubes, B, B, each three and a half (3-§-) inches in 

 diameter, and closed at one end with plugs, are screwed. In eaoli 

 section of wrought iron tubes, nine (9) of the tubes have a length of 

 three (3) feet and two (2) inches, and the remaining nine (9) have a 

 length of four (4) feet and five (5) inches each. The sections are all 

 connected by the cast iron cylinders to a steam drum, C, two (2) feet 

 in diameter and eight (8) feet long ; and this drum is connected with 

 another, D, two and a half (2-|-) feet in diameter, and eight (8) feet 

 long. (This drum has been omitted in the engraving.) From 

 this latter drum the steam leaves the boiler by the pipe E. These 

 drums are so arranged as to superheat the steam, being surrounded 

 by the products of combustion ; and in the bottom of each of 

 the drums are pipes, F, G, connecting with H, the lowest point 

 of the boiler, to allow the water carried over by the steam to drain 

 back. The feed and the water gauge and gauge cocks are con- 

 nected to the steam and water spaces by the pipes J, K, L, leading to 

 the steam drum, C, and the cross connection, H, respectively. The 

 wrought iron pipes are connected to the cast iron cylinders at an 

 angle of 20° from the vertical, the inventor claiming that as the most 

 effective position. The inventor also claims great facility for making 

 repairs by merely unscrewing a defective tube and substituting a 

 good one. 



Description of the Phleger Boiler. — (Plate 3.) 



This consists of a number of wrought iron, tubes, connected to cast 



iron tube plates, and set in brick-work. There are seventeen (IT) 



bent tubes, A, each two (2) inches in diameter, and fifteen (15) feet 



long, so arranged as to form the furnace and a " water-grate," being 



* The total of all snrfaces exposed to contact with the products of combustion is taken as heating 

 surface. 



