TETRANDRIA 51 



hasten or retard this operation of nature. A burn- 

 ing sun contributes to hasten the dropping of the 

 leaves. Hence in hot and dry summers the leaves of 

 the Lime-tree and Horse-chesnut turn yellow about 

 the first of September, whilst in other years the yel- 

 lowness does not appear till the beginning of October. 

 Nothing, however, contributes more to hasten the fall 

 of the leaves than immoderate cold or moist weather in 

 autumn ; moderate droughts, on the other hand, serve 

 to retard it. As a proof of this position, M. Adamson 

 relates, that in the year 1 759, the leaves of the Elm- 

 tree, which generally fall off about the twenty-fifth 

 of November, continued in verdure and vigour at 

 Paris, where the autumn was remarkably dry, till the 

 tenth of December. — In Worcestershire it is the 

 general opinion that this tree should be without 

 branches ; and a Baronet of very considerable 

 landed property in that county, has improved upon 

 this prevalent taste by terminating his pruning with 

 cutting off the top, and nailing a flat board on the 

 headless tree. 



The following table respecting the mean times in 

 which different trees shed their leaves, is founded 

 upon observations. 



