OF THE PINE-APPLE. 



299 



in hot-houses that are not covered, by the seve- 

 rity of the weather : this I grant is often the case 

 when the squares of glass are large, and when 

 the glazing- work is injudiciously performed. We 

 know that thin window-glass (such as is used for 

 hot-houses) is an elastic body, and that its elas- 

 ticity increases and decreases in proportion to the 

 temperature of the air. 



The method of glazing in lead is now exploded \ 

 and what glaziers term slate-glazing in putty, is 

 most generally adopted. 



When squares of glass are cut of a large size, 

 they are generally cast or warped ; therefore, it is 

 a practice with glaziers to tack them down with 

 small tacks or sprigs, in order to make the work 

 look neat. The glass bears this confinement 

 during the time the weather is warm ; but in 

 a hard frost the squares so strained frequently 

 break. 



The squares for a hot-house, where covering is 

 not intended, should not be larger than 8 by 6 

 inches ; and the groove in the wood- work to re- 

 ceive them should be 5-8ths of an inch deep, which 

 will admit of their being put in, without straining 

 them in the least from their natural form ; they will 

 then withstand the severity of the weather with- 

 out danger. Added to this, there is a great saving 

 in point of expense, by having the squares of glass 

 of so small a size, for the price of glass varies ac- 

 cording to the different size of the squares : be- 

 sides, as each square, when put in with putty, has 



