208 VARIOUS METHODS OF HEATING DESCRIBED IN DETAIL. 



house, so heated, is generally less arid than one heated by a hot- 

 air stove. This arises from the fact, that, by hot-water pipes, a 

 much larger radiating surface is presented to the atmosphere of 

 the house than by any other method, and the heat is radiated at 

 a lower temperature, and more equally diffused; hence, less 

 moisture is carried upwards by currents of heated air and 

 deposited on the glass by condensation. Thus, it is clear, that 

 the larger the heating surface that is acted upon by the air, and 

 the lower the temperature of that surface, the less moisture will 

 be drawn from the plants and the atmosphere of the house. It 

 is always desirable, however, to provide against aridity in the 

 atmosphere, as heated air will have its supply of moisture, come 

 from where it will ; and if it cannot draw it from anywhere else, 

 it will draw it from the plants, or whatever can supply the larg- 

 est quantity under its influence. For this purpose, a number 

 of troughs are made to fit on the pipes, made of zinc or gal- 

 vanized tin. These troughs may likewise be made of earthen 

 ware, and perhaps more cheaply than of zinc, though more lia- 

 ble to be broken. They may be filled with a syphon from the 

 pipes, or by a common water-pot. When moisture is required 

 in the house, an agreeable evaporation will be given off, and 

 which can be rendered still more healthful, by putting in a few 

 bits of carbonate of ammonia among the water, or common 

 pigeon's dung, or guano. As the water warms, ammonia will 

 be evolved into the atmosphere and greedily absorbed by the 

 plants. 



In recommending this system to the notice of those who may 

 be entering upon the erection of hot-houses, we would state that 

 we recommend it not only upon our own experience, but also 

 upon that of others, whom we consider much better qualified 

 to decide upon its merits. Nor do we mean to assert that it is 

 the ne plus ultra of a heating apparatus, although, under certain 

 circumstances, it is the nearest approach to it that has yet come 

 under our observation. In making this statement, we do not 

 wish to dispute the judgment of those who think differently, and 

 who have opposed it more from a feeling of groundless distrust, 

 than from any fact they can bring to bear against it. We have 

 conversed with many who would prefer heating each house with 



