110 GLASS. 



tural buildi igs so vexatious as having the roof glazed with 

 bad glass ; plants of almost every kind are certain to suffer 

 under it. Knotted and wavy glass is the worst of all, as the 

 knots and waves form lenses, and concentrate the sun's rays 

 upon the plants, and that part on which the concentrated ray 

 falls is sure to be burnt. It cannot for one moment be doubted 

 that the glass used in the majority of horticultural buildings is 

 not only inferior, but is of the very worst description ; and, on a 

 recent examination of one hundred houses, we found scarcely 

 one free from the defects here spoken of. Indeed, we are fully 

 aware of the difficulty of procuring really good glass, at reasona- 

 ble prices, for glazing hot-houses. But there cannot be a doubt 

 that the money saved is money lost; and if the vexation and 

 annoyance subsequently incurred by the use of inferior glass, be 

 taken into consideration, few persons of sound judgment will 

 hesitate in paying an increased price. 



No doubt many of our readers will suppose that we are 

 unnecessarily particular on this point, but our experience has 

 taught us a severe lesson, and one, too, which no doubt has 

 been strongly impressed upon the mind of every gardener, of 

 lengthened experience in these matters. Against such an evil 

 there is but one resource, — and a bad one it is, — which is 

 shading, either by means of cloth blinds, or by painting, the 

 worst method of the two ; but the one or the other is absolutely 

 necessary. The first is troublesome, the other is unsightly; 

 and, to be done right, both are expensive. We have a large 

 house now under our management, on which the glass is so bad 

 as to render its opacity absolutely necessary to prevent burning, 

 even when the sun's rays have lost their meridian power. 



In very small houses bad glass may be used with less chance 

 of injury, as they may be easily shaded with blinds during the 

 noonday sun ; but in very large structures this is only accom- 

 plished at very great expense ; and in curvilinear houses, and 

 houses with irregular roofs, covering them with blinds is almost 

 impossible. Painting the glass, then, is the only resource, 

 unless glass be used which does not require it. 



Little has been said on the effects of glass used in hot-houses, 

 by writers on practical horticulture. Although facts are obvious 



