352 Suggestions for a plan for Forcing-houses. 



may be held in their proper position, by an iron wire of half 

 an inch diameter passing from G to H, and attached to each 

 bar : and if such wire be reduced to a square, where it comes 

 into contact with each bar, and let in, to the necessary depth, 

 it will not in any degree obstruct the descent of the con- 

 densed vapour. 



I have given (Fig. 3), a sketch of the size and form, which 

 I suppose to be eligible for the iron bars to support the 

 glass. I imagine, that the necessary form may be easily 

 given by the roller ; and if so, I do not conceive that the 

 expense of the iron work will much exceed half that of wood, 

 including the greater surface to be painted. 



A plate of iron two inches broad, and nearly half an inch 

 thick, may be made to extend from D to E, Fig. 2, round 

 the front of the house, and along the top of it, to receive the 

 ends of the bars ; and if this plate be properly secured to 

 the brick work, I doubt whether any wood work will be 

 wanted. 



POSTSCRIPT. 



August 1, 1817. I was not prepared to state, when the 

 foregoing observations were written, whether the iron bars 

 therein mentioned, could be easily reduced to the proper 

 form by the roller of the iron mill ; nor the price per ton at 

 which, when rolled, such bars could be afforded by the manu- 

 facturer : but I have subsequently obtained the necessary 

 information from the most competent authority. The bars 

 can easily be reduced to the proper form by the roller, and 

 could have been obtained a few months ago (the price of iron 

 has since somewhat risen) at about fourteen pounds a ton ; 



