240 THE FORCING GARDENER. [B; iV 



In very wide houfes, it is cuftoinary to 

 ered light wooden or iron pillars to fup- 

 port the rafters, which are frequently a 

 greater nuifance than ornament. This is 

 done, not altogether becaufe of the inabi- 

 lity of the rafters to bear the weight of 

 the faflies ; but becaufe the rafters fall down 

 in the middle, which they would even do- 

 by their own weight, and obftrud the free 

 running of the fafhes, in the admiffion of 

 air, &c. There is a method of .obviating 

 this matter, and rendering the pillars ufe- 

 lefs } which, though very fimple, is per- 

 haps not generally underftood, and there- 

 fore may be worth the relating. 



Suppofe the rafter nine inches deep at 

 either end, let it be made ten in the 

 middle, rounding it gradually away to the 

 extremities \ whereby, when it comes to 

 fettle, the furface will become perfectly 

 ftraight. This rnuft be underftood of the 

 upper furface of the rafter and the fafli- 

 beds, and not of the under fide 3 which laft 

 will become roundifh as it fubfides. This 

 is what is termed, " cambering the raf- 



ten" 



In- 



