Woodwork and mechanical drawing . — 61 — LUMBERING The trees are cut down. The winter time is the best timefor cutting, as there is less sap in the tree at this time of theyear. The summer is the next best, the fall and the spring beingthe least favorable times. The trees are stripped of theirbranches, and shipped to the saw mill. Here they are sawedinto timbers, planks, boards, etc. Seasoning. Lumber cut from freshly felled trees is not fitfor use in permanent structures of any kind, as it is green. It. Upper, sawing logs into lengths; lower, a large load of white pine logs; right,yellow pine
Woodwork and mechanical drawing . — 61 — LUMBERING The trees are cut down. The winter time is the best timefor cutting, as there is less sap in the tree at this time of theyear. The summer is the next best, the fall and the spring beingthe least favorable times. The trees are stripped of theirbranches, and shipped to the saw mill. Here they are sawedinto timbers, planks, boards, etc. Seasoning. Lumber cut from freshly felled trees is not fitfor use in permanent structures of any kind, as it is green. It. Upper, sawing logs into lengths; lower, a large load of white pine logs; right,yellow pine in a southern forest. contains sap and moisture which will evaporate and cause thelumber to shrink, especially across the grain. Some woodsshrink as much as one inch to a board twelve inches wide. Inlength lumber shrinks very little. It is evident what wouldbecome of a structure made from wood in this condition. Toprevent this the lumber is seasoned. That is, it is piled in astack in such manner that the air may circulate around eachpiece. It is left in these stacks for a period ranging from threemonths to four years, depending on the lumber, its thickness, — 62 — and the use for which it is designed. Some of the best gradesof lumber are placed under open sheds to dry to protect themfrom snow, rain, and the direct rays of the sun. Too fast dryingcauses checks and cracks. Kiln Drying. Lumber that is used for furniture should bekiln dried as well as air dried. The lumber is piled into a roomth
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Keywords: ., bo, bookcentury1900, bookdecade1910, booksubjectmechanicaldrawing
