PRESERVATION OF TIMBER. 109 



one or more of the roots to effect the imbibition. He next bored a 

 hole into the bottom of the trunk, still erect ; and having brought 

 the cavity thus made to communicate with a reservoir, he still suc- 

 ceeded. This last plan was still further simplified in proceeding as 

 follows : the trunk of the tree is pierced by an auger through nearly 

 the whole diameter. Into the auger-hole thus made, a narrow saw- 

 is passed, by working which on either side, the trunk is divided in- 

 ternally to a very considerable extent, and the majority of its sap- 

 vessels are thus cut across and made accessible. An impervious 

 cloth is then tied round the trunk, below the opening, and this is 

 made to communicate with the reservoir of liquid.* 



M Boucherie was almost necessarily led, in the course of his ex- 

 periments, to inquire whether the absorbing power of trees differed 

 at different seasons or not. He ascertained by trials made in the 

 months of December and February, that though in the oak, the horn- 

 beam, and the plane, the solution of pyrolignite of iron always rises 

 several feet, and even several yards, yet that in the colder season of 

 the year, it never rises so high as it does in summer, in spring, and 

 especially in autumn, the season in which the power of ascent is 

 most remarkable. This conclusion is obviously of interest pbysio- 

 logically. It proves that if winter be a season of repose for the sap, 

 it is not so absolutely. There is one remarkable exception to the 

 general fact now announced, and this occurs among the resinous 

 trees that keep their leaves till the spring. It has been ascertained, 

 by direct experiment, that the ascent of tlie sap conliuues through 

 the whole course of the winter in the cone-bearing trees, and this to 

 such an extent, that it is always possible to impregnate every part 

 of their trunk by the way of simple absorption at any period of the 

 year. As M. Boucherie remarks, this fact might even have been 

 foreseen from the fresh and green state of the leaves of these trees. 



It now became important, in connection with the practical appli- 

 cation of M. Boucherie's view's, to ascertain whether or not the 

 penetration was energetic in the ratio of the vigor of the tree itself, 

 in proportion as it was more numerously provided with branches, 

 more thickly covered with leaves. Experiment showed that the 

 penetration still takes place after the removal of the greater number 

 of branches, provided only the leading bough or terminal crown be 

 left. A stem furnished with a number of leafy branches continues, 

 as has been said, to imbibe, though separated from the roots ; but 

 for how long a time will it continue to do sol This was a capital 

 point to determine. At the end of September, the bottom of a pine- 

 tree, about 14 inches in diameter, was first put into the solution 48 

 hours after it had been felled ; nevertheless the imbibition was com- 

 plete. In June the same success attended the experiment made on 

 a plane that had been cut for thirty-six hours. Still it is certain 

 that the penetration takes place with so much the more energy as it 

 is arranged close upon the time of the felling. The power by which 

 it is determined declines rapidly after the first day is passed, and by 



* Boucherie, Ann. de Chimie, t. Ixxiv. p. 134. 2e s6rie 

 10 



