72 STEPHEN HALES 



some slight interest, for Newton died on March 20, and Vegetable 

 Staticks must have been one of the last books he signed. 



The dedication is to George Prince of Wales, afterwards 

 George III. The author cannot quite avoid the style of his 

 day, for instance : " And as Solomon the greatest and wisest of 

 men, deigned 1 to inquire into the nature of Plants, from the 

 Cedar of Lebanon, to the Hyssop that springeth out of tJie wall. 

 So it will not, I presume, be an unacceptable entertainment to 

 your Royal Highness," etc. 



But the real interest of the dedication is its clear statement 

 of his views on the nutrition of plants. He asserts that plants 

 obtain nourishment, not only from the earth, " but also more 

 sublimed and exalted food from the air, that wonderful fluid, 

 which is of such importance to the life of Vegetables and 

 Animals," etc. We shall see that his later statement is not so 

 definite, and it is well to rescue this downright assertion from 

 oblivion. 



His book begins with the research for which he is best 

 known, namely that on transpiration. He took a sunflower 

 growing in a flower-pot, covering the surface of the earth with 

 a plate of thin milled lead, and cemented it so that no vapour 

 could pass, leaving a corked hole to allow of the plant being 

 watered. He did not take steps to prevent loss through the 

 pot, but at the end of the experiment cut off the plant, 

 cemented the stump and found that the " unglazed porous 

 pot" perspired 2 ozs. in 12 hours, and for this he made due 

 allowance. 



The plant so prepared he proceeded to weigh at stated 

 intervals. He obtained the area of the leaves by dividing them 

 into parcels according to their several sizes and measuring one 

 leaf 2 of each parcel. The loss of water in 12 hours converted to 

 the metric system is 1-3 c.c. per loosq. cm. of leaf-surface ; and 

 this is of the same order of magnitude as Sachs' result 3 , namely 

 2*2 c.c. per 100 sq. cm. 



1 The original reads "deigned not," an obvious slip. 



2 This he does by means of a network of threads inch apart. Pfeffer, Pfianzen- 

 physiologie^ ed. I, I. p. 142, recommends the method and gives Hales as his authority. 



3 Pflanzenphysiologie, 1865 (Fr. Trans. 1868), p. 254. 



