. Elementary woodworking . Fig. 73. Log cut lengthwise, showinghow Grain is formed 60 ELEMENTARY WOODWORKINCx. Fig. 74. Showing WeatherChecks and Shake Looking at the length of the log we see that the lines in a board, which we call the grain, are really the edges of the annual rings. It often happens in the forestthat the wind sways the treesto such an extent that the an-nual rings separate and slide onewithin the other; this produces^ a defect in the wood called ashake (see s, Fig. 74). There are other characteris-tics of wood known as warjnngand a tree has been cut down the
. Elementary woodworking . Fig. 73. Log cut lengthwise, showinghow Grain is formed 60 ELEMENTARY WOODWORKINCx. Fig. 74. Showing WeatherChecks and Shake Looking at the length of the log we see that the lines in a board, which we call the grain, are really the edges of the annual rings. It often happens in the forestthat the wind sways the treesto such an extent that the an-nual rings separate and slide onewithin the other; this produces^ a defect in the wood called ashake (see s, Fig. 74). There are other characteris-tics of wood known as warjnngand a tree has been cut down the cut end at first looks like Fig. 72. If it is allowed to lie for some time exposed to the weather, its appearance changes to Fig. 74. This is due to the evaporation of the sap, and as there is more sap toward the outside, the shrink-age is greatest there and becomes less toward the center where the heartwood is comparatively dry. This is an important fact to know, because if we had cut the log, while it was still green, into planks, as shown in Fig. 75, the
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