By Thomas Andrew Knight, Esq. 231 



It has been objected, that the water which drops from 

 bars of iron is extremely noxious to Pine Apple plants ; but 

 I have not found this to be in any degree the case : for having 

 placed a plant in such a situation that the water from a cast 

 iron rafter dropped upon it, in summer, and removing it only 

 as soon as the mould became sufficiently moist, I could not 

 discover that the plant had, during a month, sustained the 

 slightest injury. Another objection made to iron roofs is, that 

 the metal is very subject to rust. This is perfectly true, pro- 

 vided they be not kept well painted; but if one third of the 

 sum requisite to keep a wooden roof properly painted be 

 expended upon the iron roof, no injury will ever be sus- 

 tained from the liability of that to suffer from rust. I must, 

 however, take this opportunity of observing, that the bars of 

 all the iron roofs I have yet seen have been exceedingly ill 

 formed. The metal, instead of being rolled thin with grooves, 

 and made to descend into the house far below the level of the 

 glass, should be compressed into the least compass consist- 

 ent with sufficient strength ; and its lower surface, instead of 

 being brought to a thin edge, should be hemicylindrical in 

 form. None of the edges or angles, which are now presented, 

 and which are most subject to rust, would then exist ; less 

 shade would be thrown upon the plants in the mornings and 

 evenings ; and the condensed steam would be less subject to 

 drop from the bars upon the plants ; though this, in a house 

 constructed as mine is, can never do any injury. 



I have remarked, in a former communication,* that I sus- 

 pected Pine Apple plants might suffer under the influence of 

 a bright sun during the whole length of an English summer's 



* Horticultural Society's Transactions, Vol. iv. page 548. 



vol. v. H h 



