686 Transactions of the American Institute. 



much more smooth. For many uses, when only cue color is 

 required, the coloring material is added to the pulp. 



THE DAVIS SUPERHEATING STEAM BOILER. 



Mr. Wrio^ht illustrated on the blackboard the arrangement of 

 the Davis boiler, which is simply an upright tubular boiler, having 

 above the tubes a series of hollow globes, Avhich are connected by^ 

 pipes, and through which the steam must pass on its way to the 

 cylinder. Within this circular series of hollow globes, is the steam 

 drum. It is claimed that the effect of the passage of the hot pro- 

 ducts of combustion around these globes superheats the steam, and 

 that steam is not cooled on its passage to the cylinder to as low a 

 degree as that in the main parts of the boiler. The novelty in this 

 boiler is not of great importance. It is doubtless an efficient boiler, 

 but the discussion which followed on its merits seemed to indicate 

 that it is not more safe than the ordinary tubular boiler. 



THE BABCOCK AND WILCOX STEAM ENGINE. 



R. N. Thurston, of the U. S. Navy, explained, b}^ means of 

 diagrams on the blackboard, the construction of this engine, which 

 is fully set forth in the following paper: 



The inventors of this engine make no pretension to the introduc- 

 tion of radical improvements in the principle of using steam expan- 

 sively, but they have devised and perfected a new and simple 

 method of operating and controlling the action of the valves for 

 admitting and cutting oft' the steam, by means of which better 

 results are obtained than by the devices heretofore in use. 



The adaptation of a cut-oft" mechanism to act in conjunction with 

 a plain slide valve, the latter to admit and exhaust the steam, and 

 the former to close the port at any desired point in the stroke, has 

 been a favorite pursuit of engineers for the past half centur}'; but 

 in all arrangements previous to the invention of Babcock & Wilcox, 

 the motion of the main valve had more or less cfiect upon the 

 action of the cut-oft' and the latter would not work with the desired 

 rapidity at all points, nor would it admit of a range of motion 

 throughout the stroke of the piston. Nine-tenths of all the expan- 

 sion engines now built in Europe have some modificalion of this 

 form of valve gear, and the engine of Messrs. Farcot & Sons, which 

 received the grand prize at the late Paris Exposition, was of this 

 class. 



One of the points in which the Babcock & Wilcox engine difi'ers 



