1018 Transactions of the American Institute. 



any part gives out there is no large single body of water to flasli into 

 steam and thus cause the destructive effects so common to steam 

 boiler explosions. 



10th. All parts should be readily accessible for cleaning and 

 repairs. 



Tliis boiler is composed of lap-welded wrought iron tubes, placed 

 in an inclined position and connected by T heads with each other, 

 and a horizontal steam and water drum, the T heads forming verti- 

 cal passages at each end, while a mud-drum connects the tubes at the 

 lower end. The tubes are " staggered " (or so placed that one row 

 comes over the spaces of the previous row), and the whole are held 

 together by a series of strong bolts. The fire is made under the 

 higher end of the tubes, and the products of combustion pass up 

 between the tubes into a combustion chamber under the steam and 

 .water drum; from thence they pass down across the tubes, then 

 once more up through the spaces between the tubes" and off to the 

 chimney. The water is fed in at one end of the mud-drum and 

 blown out at the other ; and the steam is taken out at the top of -the 

 steam drum, near the back end of the boiler. 



ClKCULATION OF WaTER. 



The water being inside the tubes, as it is heated tends to I'ise toward 

 the higher end, and as it is converted into steam — the mingled 

 column of steam and water being of less specific gravity than the 

 solid water at the back end of the boiler — rises through the vertical 

 passages into the drum above the tubes, M'here the steam separates 

 from the water and the latter flows back to the rear and down again 

 through the tubes, in a continuous circulation. As the passages are 

 all large and free this circulation is very rapid, and produces three 

 very important advantages : 



1st. It sweeps away each particle of steam as fast as formed, and 

 supplies its place with a particle of water, thereby absorbing the heat 

 of the fire to the best advantage. 



2d. It causes a thorough commingling of the water throughout the 

 boiler, and a consequent equal temperature, thus preventing those 

 very serious strains from unequal expansion, M-hicli occur in all boilers 

 of ordinary constructions, and which are a frequent cause of explo- 

 sions. 



3d, The ra])id circulation prevents, to a great degree, the formation 

 of deposits or incrustations upon the heating surfaces, sweeping them 



