A practical course in botany : with especial reference to its bearings on agriculture, economics, and sanitation . In laying shingles, why are they made to touch, if the work 1: donein wet weather, and placed somewhat apart, if in dry weather? (136.) 5. What is the difference between timber and lumber? Between aplank and a board ? Between a log, stick, block, and billet ? 6. Why does sap wood decay mjre quickly than heartwood? (131.) 7. Explain the difference between osmosis, diffusion, capillarity, andimbibition. (9, 56, 57, 136; 53.) VI. FORESTRY 138. Practical bearings. â This part of
A practical course in botany : with especial reference to its bearings on agriculture, economics, and sanitation . In laying shingles, why are they made to touch, if the work 1: donein wet weather, and placed somewhat apart, if in dry weather? (136.) 5. What is the difference between timber and lumber? Between aplank and a board ? Between a log, stick, block, and billet ? 6. Why does sap wood decay mjre quickly than heartwood? (131.) 7. Explain the difference between osmosis, diffusion, capillarity, andimbibition. (9, 56, 57, 136; 53.) VI. FORESTRY 138. Practical bearings. â This part of our subject isclosely related to lumbering and forestry. The business ofthe lumberman is to manufacture growing trees into mer-chantable timber, and to do this successfully he must under-stand enough about the structure of wood to cut his boardsto the best advantage, both for economy and for bringing outthe grain so as to produce the most desirable effects forornamental purposes. 139. Forestry has for its object: (1) the preservationand cultivation of existing forests; (2) the planting of new THE STEM 125. Plate 7. âTirnlM-r iv,- sp.,il,.,l l,v -iAuMn,- l-- â mirl, ;,l,,,â- iâ ,,,ilv how the cruwdcd .\ .uin>^; l inilicr in the I .mcLlmmiumI i- n-litinti itcif, the lowerbranches dying ofY early from ovcrshading, leaving tall, atraight, clean bules. (FromPiNCHOT, U. S. Dept. of Agr.) 126 TRACTICAL COURSE IN BOTANY ones, or the reforestation of tracts from which the timber hasbeen destroyed. Forests may be either pure, that is, com-posed mainly of onekind of tree, as a pineor a fir wood ; or mixed,being made up of a vari-ety of different growths,as are most of our com-mon hardwood Enemies of theforest.â-The first stepin the preservation ofour forests is to knowthe dangers to bej2;uarded against. Thechief of these are*<\) fires; (2) the igno-rance or recklessness ofman in cutting forcommercial purposes;(3) fungi; (4) injurious insects; (5) she
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