245. In many kinds of the " hard-woods," and especially in the 

 oak, ash, elm, etc., each annual layer is more sp miry and porous on 

 the inner side, and harder on the outer side. The former is some- 

 times called the fjn'imj and the latter the nntnmiml growth. This 

 aurumnal growth is, however, formed in the summer, and its dens- 

 ity and relative thickness appears to depend upon the character of 

 the M'uxiii that follows after it lias been deposited. If it remains 

 humid and cold, it will be les< dense than if it be dry and warm. 

 The amount of growth for the year is usually determined by the 

 weather in the spring and early summer. 



240. In exceptional eases, such as an early and protracted drouth, 

 followed by heavy rains and a warm autumn, a second growth may 

 start ; the buds may expand into leaves, and blossoms may appear. 

 In such eases, it is possible for a double ring of growth to form, but 

 it will not lie entirely distinct in every part. Such an autumn, if 

 it is followed by a cold winter, is very apt to prove fatal to trees, or 

 at leasl to check their growth for a time, if it does not destroy them. 



247. In tropical woods, the 



annual layers are obscure, and 

 the age of a tree can not i 

 ascertained from them. 



24s. In the soft-woods, th- 

 is >carcely any difference be- ~ 



tweeil thcHver< -Hid the -eii-i-"' 1 - Sl>11 ''"ii " f Mahc.irimy. Mi-pwiii- imlNMnrt 

 ' ' '" not -.lowtliinaTrui.H'ul W 1. 



ration between the growth of 



different years is sometimes difficult to find. 



241). Deciduous trees, when stripped of their leaves, as sometimes 

 occurs from insect ravages, will put forth a new crop, from the buds 

 intended for the next season. The formation of wood is thereby 

 greatly checked, and the foliation of the next season weakened. 

 The chance of blossoms for the coming year may also be ruined. 



2 ">(>. In cross-sections made years ~.~, - _ Xf ram^ . -- 







afterwards, the record of the sea- ?l'i i " * 



s- us for a lon-r ]>eriod may be de- 

 termined, at least in effect, by the 

 width of the rings of annual 



trrowth. We sometimes find, at &>. Effectof Different Seasons upon the 



Growth of Wood. 



recurring intervals, a narrow ring, 



perhaps in every third year, that may have been caused by the loss 



