FORCING DEPARTMENT. 310 



quired. It is, also, a great preservation to the glass, 

 owing to its non-absorbing qualities, an advantage 

 which wood does not possess. The oil from the putty 

 is never abstracted from it by metal substances, as it 

 is in wood, consequently the putty 'remains sound 

 on the copper rabbits, and prevents the glass being 

 shaken out ; while, as soon as the oil is absorbed from 

 it by the wood bars, the putty scales off, and away 

 goes the glass to destruction. 



RAFTERS, &C 



Where strength again is requisite, as in the Rafters, 

 Standards, &c. I am decidedly of opinion that cast 

 metal is the best material for this purpose, as it is 

 not subject to swag by weight, nor so liable to cor- 

 rode and exfoliate as wrought iron. 



SASH FRAMES. 



The frames of the lights may be either made of 

 wrought iron or wood ; for this purpose, I certainly 

 prefer the latter material, as it renders the sashes 

 much lighter, and easier moved up or down, than 

 those with iron rims. They are, also, easily re- 

 paired ; and, by having a few of the different lengths 

 of the copper bars as a reserve, an entire light 

 might be got ready for re-glazing in much less than 

 half the time that would be requisite to prepare a 

 wooden sash. Although the wooden rims are not 

 so durable as those composed of metal, new frames 

 can be readily substituted as required. 



