Proceedings of the Polytechnic Association. 889 



only the proper equivalents of carbon (and in bituminous coal also 

 hydrogen) with oxygen, but in forming this combustion at a sufficient 

 degree of temperature to produce a perfect ignition before permitting 

 the flame and gas to be subjected to the refrigerating effects of the 

 boiler. Is not this point, the requisite temperature for a perfect 

 ignition, more worthy the attention of engineers than is generally 

 supposed ? 



Mr. T. R. Pickering said his experience confirmed the remarks of 

 Mr. Cole. 



Mr. C. E. Emery stated that a forced draft makes a very hot fire 

 and burns more coal ; it requires, therefore, more heating surface to 

 absorb the heat of the products of combustion. If the heat that passes 

 up the smoke pipe of an ordinary boiler could be utilized in vaporiz- 

 ing water, and the draft be obtained by means of a blower, much 

 saving of fuel would be eflTected. In a marine boiler some fifty -three 

 per cent of the evaporation is due to the heating surface in the 

 furnace alone. The surface near the furnace is nearly as efficient, and 

 the remainder of the surface are less and less efficient, the further 

 they are removed from the furnace. 



Globe Yalve. 



Mr. Henry Burt exhibited his Perpetual Globe Yalve. 



Burt & Towsley's patent perpetual globe valve is always tight, 

 and costs not half the sum of any other valve to do the same 

 work. 



Figure 1 represents the valve complete ; figure 2 is a detached 

 view of the interchangeable valve-seat ; and figure 3 is a detached 

 view of a duplicate valve. 



The shell or globe, A, fitted for connections with the pipe-sections 

 in the usual or in any suitable manner, has its neck, B, of such size 

 that the valve, C, and valve-seat, D, may be passed through it into 

 the globe. This neck has screwed into it the piece, E, through 

 which is screwed the tubular valve-stem, F. Upon the upper end of 

 this valve-stem is fixed the lower half, G, of a divided hand-wheel, 

 and passing centrally through the valve-stem is a rod, upon the upper 

 extremity of which is provided the upper half, I, of the double wheel 

 just adverted to. Upon the lower extremity of the just named rod 

 is fixed the valve, C, the latter being, of course, immediately below 

 the lower end of the valve-stem itself, with which, in this manner, it 

 is connected. 



