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XLIIT. On the Form which the Glass of a Forcing-house ought, 

 to have, in order to receive the greatest possible quantity of 

 Rays from the Sun. In a Letter to the Right Hon. Sir 

 Joseph Banks, G. C. B. P. R. S. $c. By Sir George 

 Stewart Mackenzie, Bart. F. R. S. fyc. 



Read August 1, 1815. 



Dear Sir, 



Th e debt which horticulturists owe to Mr. Knight is of 

 such a magnitude, that any attempt to improve on what 

 he has advanced may be considered hazardous, if not pre- 

 sumptuous. Yet I feel persuaded, that the lucubrations of 

 a fellow labourer will be received by him with that candour 

 and indulgence which are the distinguishing features of a 

 true philosopher ; a title which no one can deny to the Pre- 

 sident of the Horticultural Society of London. The observa- 

 tions, with which Mr. Knight has introduced his remarks, 

 on the best construction of a Forcing-house, are consistent 

 with what constantly occurs. The frequent changes of form, 

 which are announced as improvements, are sufficiently noto- 

 rious ; and I myself am one of those who have contributed 

 to their accumulation. In the second volume of the Memoirs 

 of the Caledonian Horticultural Society* I have described an 

 ceconomical hot-house, in which as great an extent of surface 

 as possible, is made use of for training. Give plants heat 

 and food, as Mr. Knight observes, and they will grow; 



* Page 55. 



vol. ii. A a 



