SECTIOJT VI. 



PROTECTION OF PLANT-HOUSES DURING COLD 



NIGHTS. 



1. Before concluding this brief treatise on horticultural 

 buildings, we will just cursorily advert to one more topic con- 

 nected therewith, which we are inclined to think is of far more 

 importance than is generally credited, at least, it certainly is so, 

 if we are to judge from the degree of its practical application, 

 viz., the protection of plant-houses, and, more especially, forcing- 

 houses, during cold nights, both with a view to the economizing 

 of fuel, and the equalization of heat. If duly considered, the 

 advantages of such covering are obvious. The low degree of 

 night temperature, which the best cultivators of the present day 

 agree in regarding as being most favorable to the healthfulness 

 ind general welfare of their plants, would depend upon the com- 

 bustion of fuel, so much less, in proportion, as the escape of 

 the internal heat, by radiation and otherwise, was prevented by 

 means of a covering exterior to the conducting surface of the 

 glass. 



The manifest advantage of such a protecting body does not 

 wholly consist in the economizing of fuel. In such n variable 

 climate as we have in the New England States, with the exter- 

 nal atmosphere acting on the glass at a temperature of 25 or 30 

 degrees below the freezing point, it is, then, almost under any 

 system of heating, unavoidably necessary to apply an excess of 

 artificial heat, to ensure the safety of the plants against injuri- 

 ous depressions of temperature. Now, if a covering of non- 

 conducting materials be employed to intercept the action of the 

 changing atmosphere upon the surface of the glass, the plants 

 will be as ^afe at a much lower internal temperature, as if no 

 such protection were afforded them, with a high t€mperatur3. 

 The plants, therefore, will, under these circumstances, be in v 



