Page:Philosophical Transactions - Volume 095.djvu/106

92 ^ ^r. Ksribttt cancemng the State in Tvhich

less rkpiflky ttf its growth. These ^ou4*ces of ^r6r tnigHt ^^ parently have ^eWi avoided by ttrttiftg off, "at diljfeirerit seicsttos, pontons of lJr6 same trmrk or %rarich : btit tTie wormd thus taade might, fe some decree, haVe impeded fte Aie )prdgtess of 'the ^ap ?h its accent, aitd iJte part l)elow might have bedh m&Ae heavier %iy the sta^ation t)f the sap, tmd ifcft aflboSre Ughter by privation of its proper quantity of nutriment. The mcfet eligible ^method therefore, tvhich occurred te me, was to select and mark in the winter some ^f the poles of an oak cdppice, where all are of «qual age, and where miny, ^f the same Sizre and growing with equal vigour, spring fixym the same stool. 'One half of thepoles which I marked and num- bered were cuft on the gist of December, 1B05, and the remainder on the 15th of the foHos4ng May, when ^he leaves Xvere tteatly half grown. Proper marks wet'c put to'distinguish atie wimer-felled from the summer-felled poles, the bark being ieft on all, ahd ail being placed in the same situation to dry.

In the beginning of August T cut off nearly equal portions from a winter and summer-felled pole, which had both grown on the same stool ; and both portions were then put in a situation, where, during the seven succeeding weeks, they were kept very warm by a fii'e. The sunlmer-felled wood was, when put to dry, the most heavy ; but it evidently contained much more water than the other, and, partly at least, from this cause, it contracted much more in drying. In the 'begin- ning of October both kinds appeared to be perfectly dry, and I then ascertained the specific gravity of the winter-felled wood to be 0.679, and that of the siimmer-felled wood to be 0.609 ; after each had been immersed five minutes in water.

This difference often per cent, was considerably more than