MECHANICS AND USEFUL AKTS. 59 



enters the fire through the grate to support combustion, and which usually 

 escapes, highly heated, through the chimney. In order to make this heat 

 available in impelling the engine, this air is compressed to a high tension, 

 and forced in under the grate by a large pump connected directly to the 

 piston-rod, and is not allowed to escape into the chimney until it has passed 

 through the cylinder and impelled the piston. By this means all the expan- 

 sion due to the change of temperature serves to develop power in the propul- 

 sion of the machine, and if, as is the case in fact, the mixture of steam and 

 heated air be cut off early, and consequently be worked very expansively in 

 the cylinder, so as to reduce it nearly to the pressure of the external atmo- 

 sphere, the gain due to the use of the air is very considerable. One great evil 

 arising from this arrangement is the too high temperature of the air. It was 

 contemplated to overcome tin's by diluting it with a greater or less quantity 

 of equally compressed air not passed through the furnace, and also by 

 showering upon it a smaU quantity of water, which, by absorbing the heat 

 and changing to steam, would cool the gaseous matter, and w.ould itself impel 

 the engine in the usual approved style. These latter features are new, we 

 presume, and peculiar to the inventor, but the use of smoke or air heated in 

 this manner has been treated before, and like Ericsson's, abandoned as im- 

 practicable, although affording undoubtedly some degree of economy over the 

 yet triumphant steam. The difficulties experienced in former trials arose from 

 the scratching and destruction of the interior surface of the cylinder, and in 

 spite of ah 1 the precautions described, the same difficulty exists in the machine 

 under notice, to such extent as to render its success extremely doubtful 

 unless some new expedient can be adopted either to free the gases from 

 particles of coal and grit, or more efficiently and constantly to lubricate the 

 w r orkmg surfaces. In short, the results so far have demonstrated that, as 

 has been the case with ah 1 previous efforts in this direction, the saving in fuel 

 by the introduction of heated air, has been far more than counterbalanced by 

 the increased expense and rapid destruction of the machinery. 



LEE AND LAENED'S STEAM FIRE ENGINE. 



A new steam engine, differing in almost every respect from all others 

 within our knowledge, has lately been constructed in New York, and several 

 tunes exhibited with apparently the most complete success. 



As originally constructed the steam could not be kept up to the proper 

 point, but rapidly declined whenever the full power was applied, so that its 

 performance resembled that of the usual man-power machines, requiring 

 intervals of rest. This difficulty has now been overcome by fixing a grate in 

 the furnace, an addition not previously supposed necessary with wood fuel, 

 and it is now able without any artificial draught to generate steam as fast as 

 it is consumed, while throwing to a great height a steady stream through 

 a one and a quarter inch nozzle for a half day at a time. Messrs. "Wellington 

 Lee and J. G-. E. Lamed, of New York, are the inventors of this combination, 

 the whole of which weighed, before the grate was added, but 6.500 Ibs., and 

 is designed to be easily and rapidly hauled in any ordinary condition of the 

 streets by two horses, without assistance from the firemen. 



