860 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



As A Marine Boiler. 

 The position for setting the boiler as described has been adop- 

 ted for stationary l)oilers, as affording an easy method for making 

 up uniformly, and uniting the sections ; as well as for conveniently 

 securing a spacious furnace chamber, the roof of which, or lower 

 series of globes, thereby having a proper elevation above the fire 

 grate. But for marine uses a trial boiler has been set up, with the 

 sections vertical. In this case the lengths across the furnace end 

 forward of the bridge wall are each successively made one globe 

 shorter at the bottom, from back to front. This effects a similar 

 relative position to the grate bars with this arrangement as with 

 the former case ; the boiler being enveloped in a double jacket of 

 plate iron, with an intervening air space. The trials with this 

 boiler have been entirely satisfactory. 



As A Radiator. 

 The same system of spheres, similarly combined, are also used 

 as radiators of heat for either steam or hot water. In these cases 

 the globes are cast three-sixteenths of an inch in thickness. A 

 boiler of thirteen spheres, representins: one horse power, will 

 supply 100 radiating globes, capable of wapming 20,000 cubic 

 feet of space, and so on in that proportion. The boiler is, how- 

 ever, adapted to any form of radiator. 



Superheating. 

 The boiler is its own superheater, without the necessity of any 

 additional or intervening apparatus ; and is found more free from 

 priming than other boilers with like conditions of water. Guard 

 or shield plates of cast iron inserted horizontally between the sec- 

 tions, below the water line, deflect the heat from the steam spheres, 

 and regulate or avert superheating. 



Comparative Description with Boilers of Wrought Iron. 



It is not easy to fully describe the distinctive features of this 

 boiler without referring comparatively to those of wrought iron. 



Cast iron absorbs and transnu'ts heat more rapidly than wrought 

 iron, and, in the absence of free oxygen, it is improved under the 

 prolonged moderate heat. But wrought iron, under like treat- 

 ment, depreciates in strength. 



This assertion may be skeptically received by many experienced 

 in treating iron. It can, however, be easily tried. There are cer- 



