VOL. LXVIII.] PHILOSOPHICAL. TRANSACTIONS 279 



active state, or in the passive, that the whole or part which was frozen, was dead 

 when thawed. 



The winter 1775-6 afforded a very favourable opportunity for making experi- 

 ments relative to cold, which I carefully availed myself of: though, previous to 

 that winter, I had nriade many experiments on vegetables respecting their tem- 

 perature comparatively with that of the atmosphere, and when they were in their 

 different states of activity. I therefore examined them in different seasons. 

 with a view to see what power vegetables have. I shall relate these experiments 

 in the order in which they were made. They were begun in the spring, the 

 actions of life on which growth depends being then on the increase; and they 

 were continued till those actions were on the decline, and also when all actions 

 were at an end, but while the passive powers of life were still retained. 



The first were made on a walnut-tree, g feet high in the stem, and 7 feet in 

 circumference in the middle. A hole was bored into it on the north side, 5 feet 

 above the surface of the ground, 1 1 inches deep towards the centre of the tree, 

 but obliquely upwards, to allow any sap, which might ooze through the wounded 

 surface, to run out. I then fitted to this part a box about 8 inches wide and 5 

 deep, and fastened it to the tree : the bottom of the box opened like a door with 

 a hinge. I stuffed the box with wool, excepting the middle, opposite to the 

 hole in the tree : for this part I had a plug of wool to stuff in, which, when the 

 door was shut, inclosed the whole. The intention of this was to keep off as 

 much as possible all immediate external influence either of heat or cold. 



The same thermometer with which I made my former experiments, 7v inches 

 lono- was sunk into a long feather of a peacock's tail, with a slit on one side to 

 show the degrees ; by this means the ball of the thermometer could be introduced 

 into the bottom of the hole. 



Exp. 1. March 29th, I began my experiments at 6 in the morning, the at- 

 mosphere at 57°i, the thermometer in the tree at 55"; when it was withdrawn 

 the quicksilver sunk to 53°, but soon rose to 57"-^^.* This experiment was re- 

 peated 3 times with the same success. Here the tree was cooler than the at- 

 mosphere ; when one should rather have expected to have found it warmer, since 

 it could not be supposed to have as yet lost its former day's heat. — Exp. 1. April 

 4th, half past 5 in the evening, the tree at 56°, the atmosphere at 62°; the 

 tree therefore still cooler than the atmosphere. — Exp. 3. April 5th, wind in the 

 north, a coldish day, 6 o'clock in the evening, the thermometer in the tree was 

 at 55°, the atmosphere at 47° ; the tree warmer than the atmosphere. — Exp. A. 

 April 7th, a cold day, wind in the north, cloudy, at 3 o'clock in the afternoon, 

 the thermometer in the tree was at 42°, the atmosphere at 42° also. — Exp. 5. 



* The sinking of the quicksilver upon being withdrawn I imputed to the evaporating ol the mois- 

 ture of the fluid on the ball. — Orig. 



