HIS CONCLUSIONS. 97 



the third (highest) branch only began to absorb 

 the sap on the 3rd of May, thirteen days after the 

 middle one. 



We see from this experiment, as HALES observes, Conciu- 

 " That the cause which produces the flow of the HALES. 

 sap does not proceed from the root alone, but that 

 it belongs to a force inherent in the stem and 

 branches. For the middle branch followed more 

 rapidly the changes of temperature, of dryness and 

 of moisture, than the two others, and absorbed the 

 sap nine days before one, and thirteen days before 

 the other, both of which, during this time, poured out 

 sap instead of absorbing it. (The cause of the efflux 

 and pressure had, in the older branch, disappeared, 

 and given place to an opposite influence, while it 

 still continued active in the two younger branches.) 



" The middle branch was 3 feet 8 inches higher 

 than that next the stem. The height of the mer- 

 cury in the three tubes was, respectively, 14|, 12^, 

 and 13 inches. The maximum was 21, 26, and 26 

 inches. These numbers prove that the greater length 

 of the middle branch had no perceptible influence 

 on the height of the mercury, as compared with that 

 in the other tube." 



In his experiment XXXVIII., HALES observes, Effect of 

 " Moisture and warmth made the sap most vigorous, of shade on 

 If the beginning or middle of the bleeding season, thesap. 

 being very kindly, had made the motion of the sap 

 vigorous, that vigour would immediately be greatly 

 abated by cold easterly winds. 



H 



