Bulletin Volume 6-8; No. 13

Bulletin Volume 6-8; No. 13

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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1892 edition. Excerpt: ...by an increase in strength, stiffness, and toughness. A (2) Variation in strength goes generally hand in hand with variation in specific gravity., (3) The strongest timber is found in a region lying between the pith and the sap at about one-third of the radius from the pith in the butt log; in the top log the heart portion seems strongest. The difference in strength in the same log ranges, however, not over 12 per cent of the average, except in crushing across the grain and shearing, where no relation according to radial situation is apparent. (4) Regarding the variation of strength with the height in the tree, it was found that for the first 20 to 30 feet the values remain constant, then occurs a more or less gradual decrease of strength, which finally, at the height of 71) feet, amounts to 20 to 40 per cent of that of the butt log for the various exhibitions of strength. (5) In shearing and crushing across and parallel with the grain, practically no difference was found. (6) Large beams appear ll) to 20 per cent weaker than small pieces. (7) Compression tests seem to furnish the best average statement of value of wood, 'and if one test only can be made this is the safest, as was also recognized by Bauschinger. " The investigations into the effect of bleeding the trees for turpentine leave now no doubt of the fact announced in a preliminary circular, that bled timber is in no respect inferior to unbled timber. This conclusion, to which the mechanical tests lent countenance, is strengthened by the chemical study of Mr. M. Gomberg into the distribution of resinous contents throughout the trees bled and unbled. These show what physiological considerations would lead us to anticipate, that the resinous contents of the heart wood take no part in...show more

Product details

  • Paperback | 194 pages
  • 189 x 246 x 10mm | 354g
  • Rarebooksclub.com
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 1236633172
  • 9781236633170