242 



THE PEACH AND NBCTAEINE. 



worked aa well as more ornamental than those formed with spare glass 

 lights. They generally partake more of the character of glass walls than 

 glass cases, the lights being almost yerticaJ. Hence they inclose bnt 

 little air, and this is one of their greatest weaknesses. All narrow glass 

 cases heat, and consequei^tly also cool, with great rapidity, thus requiring 

 Uberal and prompt ventilation and the covering of the glass, to render 

 them efficient, otherwise the glass draws the flowers forward into abnormal 

 tenderness by day, and exposes them to so mnch cold at night that the 

 glass proves of bnt donbtfnl advantage. It is, in fact, highly problematical 

 whether the extra liabUity to injury induced by day forcing is baJanoed 

 by the extra protection afforded by a mere glass screen at night. 



II. — Orchard Houses. 



The majority of these are span-roofed (Fig. hi) ; bnt lean-to orchard 

 houses also abound. It is obvious that the term is applied rather to form 

 of trees and style of culture than to any special variety of glass house. 



Fia. 51. 



The term is also used by many cultivators to designate houses that are 

 either unheated, or to a less extent than peach houses. Most of these 

 distinctions are^ however, arbitrary, and as orchard houses increase and 

 multiply, they will probably lose their present significance, for there 

 seems no good reason why a peach orchard under glass — :that is, an orchard 

 house — should not be forced or treated exactly like other peach houses. 

 Orchard houses also differ broadly from glass oases, inasmuch as they 

 are seldom erected against walls already furnished with peach trees, but 

 rather filled with trees of a more free style of growth. However, there 

 are also orchard liouses filled with cordons and trees trained on trellises. 



