14 THE ORCHID-GROWER'S MANUAL. 



inches wide ; twenty-one oz. glass is best, not being easily- 

 broken. I remember seeing an Orchid house after a hail- 

 storm much injured, a large portion of its valuable contents 

 being nearly spoiled. The glass used in this instance was 

 only sixteen oz., while, if it had been twenty-one oz., it would 

 most likely have withstood the storm. I should recommend 

 twenty-one oz. glass, or even more, as not being likely to get 

 broken by cleaning or otherwise. Too large squares are bad, 

 being apt to get broken by frost. The upright glass at the 

 sides ought to be of the size stated above, to correspond with 

 that in the roof and also in the ends and the door ; the sash 

 bars should have a small groove down them to carry drip to 

 the bottom, in order to prevent it dropping on the plants ; 

 even small pieces of zinc nailed to the bars serve to form a 

 sort of gutter to carry off drip. 



Ventilation. 



This is of great importance ; for if cold air is allowed to 

 pass among the plants they will not thrive, and all care 

 which has previously been bestowed on them will be in vain. 

 Means of ventilation should, therefore, be provided for, near 

 the ground, close to the hot-water pipes, in order that the 

 air may be warmed in entering the house. In the houses 

 here there are four ventilators on each side, two to each house. 

 The ventilating shutters are made of wood, about two feet 

 long, one foot wide ; sliding slate ventilators answer perhaps 

 better : there should be one glass ventilator at the south end 

 near the roof, and one at the north end, as the top lights of 

 the house are best not made to slide. 



/Shading. 



Every Orchid-house requires to be shaded. The best ma- 

 terial is canvas, and there should be blinds on each side, with 

 a strong lath at the top to nail the canvas to, and a roller 

 at the bottom. The canvas must be nailed to the roller, but 



