. Essentials of botany. Botany; Botany. 348 ESSENTIALS OF BOTANY spring and summer growth (Fig. 236). Among the com- monest and most typical of the ring-porous woods are ash and oak, and of the diffuse-porous ones, birch and maple. 419. Wood as Fuel Although coal (Sect. 375) is the fuel of the world's great industries, yet there are large areas throughout which wood is still the principal fuel. All kinds of wood can be burned, but for certain purposes those kinds are preferred which make an abundant flame or which leave solid beds of glowing coals. In general the heating effect of well-dried w
. Essentials of botany. Botany; Botany. 348 ESSENTIALS OF BOTANY spring and summer growth (Fig. 236). Among the com- monest and most typical of the ring-porous woods are ash and oak, and of the diffuse-porous ones, birch and maple. 419. Wood as Fuel Although coal (Sect. 375) is the fuel of the world's great industries, yet there are large areas throughout which wood is still the principal fuel. All kinds of wood can be burned, but for certain purposes those kinds are preferred which make an abundant flame or which leave solid beds of glowing coals. In general the heating effect of well-dried wood when burned is nearly av-. -,-ar Sycamore Birch Fig. 236. Difiuse-Porous Woods. (Somewhat magnified.) ar, annaal rings. proportional to its weight per cubic foot. The fuel value per cord is therefore dependent on the weight per cord, and the heaviest woods, such as hickory, most of the oaks, hackberry, and some kinds of ash, are the best for burning. For certain purposes, where a concentrated smokeless fuel which lights easily and does not readily go out is required, charcoal is employed. Generally the heaviest woods make a dense charcoal of great heating power. 420. Forestry. — Forestry as a science deals with the factors which concern the occurrence and growth of for- ests. Forestry as an art deals with the rules of forest. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Bergen, Joseph Y. (Joseph Young), 1851-1917. Boston, Ginn
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