All kinds of tin her several natural defects occur. There are caused by the nature of the soil upon which the tree grew and also by the changes in nature to which it was subjected while growing. 1. Heart shakes: These are the splits or cracks widest at the center and diminishing towards the outside circumference. This defect usually occurs in over matured trees and is probably caused due to the shrinkage of the heartwood. Heartwood shake which follows a straight course along the timber is not so serious as compared with that which follows a twisted course. 2.Star Shakes: These are radial splits or cracks widest at the circumference and get diminishing towards the center of the tree. Star shakes are more serious as they tend separate the log into a number of pieces when it is sawn. These may arise mostly from severe frost and fierce heat of sun.3. Cup Shakes or Ring Shakes: There are formed by the rupture of the tissues in a circular direction across the cross-section of a log, usually along annular rings. When the rupture extends only part around, it is called a cup shake and when the whole way round or almost so a ring shake. 4. Radial shakes: These are similar to star shakes but they are fine, irregular and numerous, They occur when tree is exposed to sun for seasoning, after being felled down. They run for a short distance from bark towards the center, then follow direction of annual ring and ultimately run towards pith. 5. Rind Galls The rind means bark indicates abnormal growth. hence, peculiar curved swellings
المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .
الرجوع الى لوحة التحكم
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