and the Economy of Fuel. 153 



curiosity and excite the attention of ingenious men, 

 of such as take pleasure in exercising their ingenuity 

 in contriving and perfecting useful inventions, and who 

 delight in contemplating the progress of human in- 

 dustry. 



Model of a perpetual Lime-kiln. 



The particular objects principally had in view in the 

 construction of this lime-kiln (which stands in the court- 

 yard of the Dublin Society) were,yfrj-/, to cause the fuel 

 to burn in such a manner as to consume the smoke, 

 which was done by obliging the smoke to descend and 

 pass through the fire, in order that as much heat as 

 possible might be generated. Secondly, to cause the 

 flame and hot vapour which rise from the fire to come 

 into contact with the limestone by a very large surface, 

 in order to economize the heat and prevent its going 

 off into the atmosphere, which was done by making 

 the body of the kiln in the form of a hollow truncated 

 cone, and very high in proportion to its diameter; and 

 by filling it quite up to the top with limestone, the fire 

 being made to enter near the bottom of the cone. 

 Thirdly, to make the process of burning lime perpetual, 

 in order to prevent the waste of heat which unavoidably 

 attends the cooling of the kiln in emptying and filling 

 it, when, to perform that operation, it is necessary to put 

 out the fire. And, fourthly, to contrive matters so that 

 the lime in which the process of burning is just finished, 

 and which of course is still intensely hot, may, in cooling, 

 be made to give off its heat in such a manner as to 

 assist in heating the fresh quantity of cold limestone 

 with which the kiln is replenished as often as a portion 

 of lime is taken out of it. 



