20 On the M Tl N of 



As to the firft, the fap had iffued on the 24th inftant at the ninth 

 incifion, which was juft below the infertion of this branch, 

 but had been kept from afcending higher, for three days pad, 

 by a great degree of cold. During thefe days, I watched 

 every morning to find when the fap would appear at the lowefl 

 incifion upon the branch ; but the cold was too great to fuffer 

 it to make any progrefs till this day. Accordingly, all the 

 feven incifions on the branch did this day bleed fucceflively, 

 from the bottom to the top, between nine o'clock in the morn- 

 ing and two in the afternoon. 



COR. 14. In anfwer to our firfl enquiry, we therefore find, that 

 the fap moved in this young branch feven feet in one day ; 

 but when the thermometer was at the fame degree of 49. the 

 fap moved in the trunk of the tree only at the rate of feven 

 feet in feven days. We may therefore, in general, conclude, 

 that the fap makes a fwifter progrefs in young than in old 

 wood ; and that, in fome cafes, the proportional difference is 

 no lefs than feven to one. 



ON the 1 6th of March, the birch on which this experiment was 

 made, being about thirty feet high and thirty-five years old, 

 bled no higher than four feet above the ground; but a younger 

 birch, {landing clofe by it, being only about fourteen years 

 old, did, on that day, bleed at the top, or fifteen feet high. 

 Many fuch inftances might be adduced to mew, that the fap 

 runs more freely, and with a quicker afcent, in young than 

 in old wood. In confequence of this, the young trees of 

 every fpecies, ccetcrls paribus^ difclofe their leaves in fpring 

 fooner than thofe which are old. 



OBS. 23. As to the fecond enquiry, the firft bleeding of thefe 

 feven incifions on the branch B was attentively marked, that 

 I might know whether the fap would firft appear on the under 

 or upper fide of each incifion, or on both at the fame time. 

 Accordingly, this morning, the fap made its firft appearance 

 upon the loweft fide of the loweft incifion, at h ; and fo fuc- 



ceffively, 



