MATERIALS FOR ORCHID HOUSES. 



45 



important, and the length must obviously be according to the quantity of plants grown. 

 Being mostly of a dwarf habit, a large number of cool orchids may be arranged in a 

 comparatively small house. When a uniform design is wanted the three compartments 

 may be built in one house, and in this case the cool house would have the same 

 aspect as the others. This will necessitate very heavy shading in the summer, but 

 from the abundance of light that reaches the plants from all sides the position would be 

 perfect for the winter treatment of the plants. Not more than half the above mentioned 

 quantity of piping need be allowed for the cool house, and fire heat is only necessary 

 during the coldest weather. 



With regard to the class of boiler required, this depends upon the size of the houses 

 and the nature of the soil in the neighbourhood. "Where there is no fear of water 

 finding its way to the stokehole the upright tubular boilers are excellent, but some kind 

 of saddle boiler should be used where water has to be contended with (see illustrations 

 pp. 251 and 252, Yol. II.). There is nothing more troublesome than a wet stokehole, so 

 if there is the least fear of water, means must be provided to drain it away. 



With regard to timber for orchid houses many are now built with teak, one of the 

 most enduring of woods, but far more costly than the best description of deal. Red 

 deal, as it is known in the trade, is very largely used in horticultural building, and is 

 excellent when carefully picked clean deals are selected, free from sap, large and dead 

 knots, and perfectly dry or seasoned. Although a lasting wood, pitch pine is not 

 suitable for orchid houses. It does very well for sills and wall plates, ridge cappings 

 and purlins, but is not so well suited for running lights, sashes and bars. A far better 

 timber is close-grained easily worked yellow deal, which in the moist heat of the structure 

 lasts well and is free from the unsightly exudations of turpentine and resin so common 

 in other foreign timbers. 



All sashes, doors, and lights must be very loosely fitted in their frames, otherwise 

 they swell and are difficult to open or shut, this leading to broken glass and hinges. 

 A quarter of an inch clearance is not too much, and if the inner stops or beads are 

 properly fitted there is no danger of draughts. In fact these are more frequently caused 

 by close-fitting sashes not properly shutting than in any other way. 



Ventilation should be continuous and on each side of span-roofed structures. 

 The lights must however work independently, for with a cold east wind blowing it 

 would be dangerous to ventilate from that side, though some air will be needed. It is 

 in this way that the lantern system of top ventilation falls short of perfection. The 



