PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 911 



circulfition of wuter within it. A flame was applied to this model 

 aad the rapid circuhxtiou of the water was made visible to the 

 whole audience. 



The object of this new invention is to overcome the objections 

 to, and prejudice against the ordinary upright and other forms of 

 boilers, in which, on account of the want of proper circulation, 

 the sediment collects upon the crown sheets and bet^vecnthe tubes, 

 thus destroying the utility of the most important heating surface ; 

 and in which the upward and downward currents so interfere Avith 

 each other, that it is impossible for the water to return to the 

 bottom, and be presented to the heating surfaces in a solid form. 



Its superiority consists in the fact that it accomplishes the fol- 

 lowing objects indispensable in a safe and efficient boiler, viz.: It 

 circulates the water in a body, (as will be seen by reference to the 

 drawings and description), thus passing it over the steam making 

 surfaces rapid)}', keeping them at the best steam making tempera- 

 ture, and taking the heat away from them as fast as thc}^ gather it. 



The circulation also, keeps the sediment from settling on the 

 tube sheet, and deposits it in the fire box legs, which fact is proven 

 by the experience of a year or more, with the dirtiest kinds of 

 water. 



The beneficial results of this boiler may be thus summed up. 

 1st. It prevents foaming. 2d. It prevents incrustation. 3d. It 

 gives dry steam. 4th. It keeps the fire surfaces covered with 

 water. 5th. It gives equal temperature. The boiler, it will be 

 seen, is simple in construction and very strong ; it is easily set up 

 and readily repaired. 



The description of the boiler and its operation will be under- 

 stood by a reference to the annexed illustration. 



'J'he vertical section through centre of boiler, shows the steam- 

 drying cone and circulating cylinder, part in section and part out- 

 side view. 



A is outside shell of boiler. B is the fire-box sheet. 



C is the lower tube-sheet. E is the upper tube-sheet. 



D is the fire-grate, resting on the foundation plate. 



F is the sheet-iron circulating cylinder or thimble around the 

 tubes, kept in place by being braced to the fire-box sheet ; extend- 

 ing from a short distance above the lower tube-sheet to the ivatei'- 

 line, dividing the water among the tubes from the water near the 

 outside shell of the boiler. 



G is the sheet iron steam-drying cone around the upper part of 



