Page:Timber and Timber Trees, Native and Foreign.djvu/71

From Wikisource
Jump to navigation Jump to search
This page has been proofread, but needs to be validated.

CHAP. IX.]
BRITISH OAK.
51


Table VI.—English Oak.
Transverse Experiments.—Second Example.
Number
of the
specimen.
Deflections. Total
weight
required
to break
each
piece.
Specific
gravity.
Weight
reduced
to
specific
gravity
1000.
Weight
required
to break
1 square
inch.
With the
apparatus
weighing
390 lbs.
After the
weight
was
removed.
At
the crisis
of
breaking.
  Inch. Inch. Inch. lbs.     lbs.
07 1.625 .125 4.125 674 780 864 168.50
08 1.625 .250 5.250 837 753 1112 209.25
09 1.500 .187 5.000 824 770 1070 206.00
10 1.625 .125 9.500 977 1005 972 244.25
11 1.750 .000 9.250 882 1003 879 220.50
12 1.500 .000 8.750 827 1002 825 206.75
Total 9.625 .687 41.875 5,021 5313 5722 1255.25
Average 1.604 .114 6.979 837 886 954 209.21
E = 605950.S = 2197.

Remarks.—No. 7 broke short: 8 and 12 with 7 to 13 inches length of fracture; 9, 10, and 11 with 15 inches scarph-like splintery fracture.

The Tables V. and VI. each refer to parcels of six pieces, which were taken from trees of good average quality and size, moderately seasoned, and fit to be applied to architectural works, the specific gravity varying from 670 to 905 in one set, and 780 to 1005 in the other. Of the twelve pieces tested, the elasticity of two, after the weight of 390 lbs. was removed, was perfect. One piece recovered its straightness to within .312 inch, while of the remainder, nine in number, the elasticity was in all something better, though not quite perfect.

The deflections varied under this weight of 390 lbs. from 3.125 to 3.625 inches in one set, and from 1.5 to 1.75 inch in the other, the ultimate deflections at the crisis of breaking varying from 5.25 to 11.00 inches, and 4.125 to 9.50 inches, respectively; while the break-