Polytechnic Association. 925 



cal pipes, after they have been covered with thin plates of disks, so 

 as to be connected at each end with a hollow metallic ring. The steam 

 is admitted into the upper hollow ring, and, after passing through 

 each of the vertical pipes simultaneously, is discharged, either as steam 

 or water, through the lower hollow ring into an exit pipe. The thin 

 plates or disks surrounding the vertical pipes are inclined so as to be 

 lowest on the outside of the apparatus. As the air, drawn in on all 

 sides, is heated in its passage between each pair of disks, it moves 

 inward and upward ; and after escaping through the upper ring con- 

 tinues to rise until it reaches the ceiling of the room, and, passing 

 along its whole area, displaces the colder air, which sinks, and is 

 soon carried to the heating apparatus, thus insuring, by perfect con- 

 vection, a uniform temperature. A novel feature in this arrangement 

 is the method of preventing the air, which has passed between the 

 heating disks, from being immediately exposed to other heating sur- 

 faces before it escapes from the apparatus. "When this steam heater 

 is placed in the basement of a building, the cold air may be admitted 

 through the upper ring, and be discharged outward on all sides, in 

 which case the disks are inclined so as to be lowest on the inside of 

 the pipes. 



Of Condensers. 

 Air being about 815 times lighter than water, at the mean tempera- 

 ture of the atmosphere, and having much less specific heat, it is 

 evident that it cannot be substituted for the condensing water used 

 in ordinary low-pressure engines of large size on account of the great 

 number of tubes which must be exposed to cold air ; but in engines 

 of very small size, varying from one man to one horse-power, it is 

 feasible to add a series of apparatus, similar to that described for heat- 

 ing by steam, in which the quantity of inflowing cool air will be 

 sufficient to condense the exhaust steam from such an engine. The 

 air which thus absorbs the heat of the steam would be conducted into 

 a ctiimney, the draft of which would be sufficient to provide a full sup- 

 ply of cold air. It is evident that in winter the air, thus heated, could 

 be utilized with such an apparatus, and the water thus condensed, 

 could be pumped directly into the boiler. 



i 

 Of Stoves. 



The steam-heating apparatus described may be modified so as to be 

 applicable to stoves ; all that would be required is the substitution of 

 the upper plate of the fire-box for the lower hollow ring. The heat 



