TROPICAL AND TEMPERATE HOUSES. 75 



and the north side with glass, — a plan which 

 admits abundance of light, and renders shading 

 wholly unnecessary. The whole structure is 

 placed on a slope, the lower part being consid- 

 erably below the outside ground-level. At this 

 lowest part is placed the furnace, and there is an 

 extra service of pipes there to maintain a stove 

 temperature. At the upper end, the pipes suffice 

 only to keep frost out. Thus in one house the 

 ferns of tropical, temperate, and frigid zones are 

 all accommodated ; and though the whole structure 

 is rough, and has been constructed on the most 

 economical principles, the interior presents at all 

 seasons a grand spectacle, and affords a most de- 

 lightful promenade." — Fern Garden, pp. 98, 99. 



Of course, to grow to perfection any of the taller 

 species of arborescent ferns, a very high roof, or a 

 dome on some portion of the structure, will be re- 

 quired. Alsophila excelsa at the Botanic Garden, 

 Cambridge, Mass., has now reached the glass at 

 the highest part of the house, some twenty-five 

 feet above the floor. This plant is many years old. 



Our greenhouses are usually built in summer ; 

 and, for this reason, there is danger of our uncon- 

 sciously making them too weak to endure the 

 strain of ice and heavy snows which the winter of 

 our rigorous Northern climate will bring. Between 

 May and October, it is " very hard to realize that 

 those charming designs contained in the English 



