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7:017 13,894,000 ⚫00003109 204307811 79.83 7.031 14,112,666 ⚫00003061 204309133 91.21 68102037 7.094 16,246,966 ⚫00002659 203806701 68.28 7.028 15,787,666 ⚫00002737 7.087 16,534,000 .00002613 7.038 13,971,500 ⚫00003092 7.007 13,845,866 ⚫00003120 6.920 13,790,000 ⚫00003133 7.080 13,136,500 ⚫00003288 6.979 15,394,766 ⚫00002806 7.051 15,852,500 ⚫00002725

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6.953 13,294,400 ⚫00003250 1917 07881 7.185 16,156,133 ⚫00002674 1912 06141 6.969 14,322,500 ⚫00003016 190309412 6.955 14,304,000 ⚫00003020 189007378 6.916 12,259,500

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the external, and do the internal diameter,
in inches.

the external, and do the internal depth or
vertical diameter in Elliptical sections.
the external, and d

= the internal breadth or

horizontal diameter in Elliptical sections.

L = the length of the beam in feet.

W

T

the load in lbs., tons, &c., dependent on the terms of Mr.

M1 = Multiplier which varies with the Material, mode of fixing, loading, &c.: the value for rectangular and cylindrical beams is given by Tables 64, 65, 66, and the Ratios in (359), (362). (335.) The value of M, may be found from direct experiment by rule (327). Its most useful value is when W = the ultimate or breaking weight in the centre of a rectangular beam supported at both ends :-in that case it is simply the breaking load of a beam 1 inch square and 1 foot long.

Table 64 gives in col. 7 the mean value of M, for the breaking weight of 54 kinds of British cast iron at 2063 lbs., or 18.4 cwts., or 92 ton, and of course W will come out in lbs., cwt., or tons according to the Multiplier used:-col. 10 gives Mr for the safe dead load, which is taken at 3rd of the breaking weight. This Table is based on Fairbairn and Hodgkinson's experiments.

Table 65 gives the value of MT for Timber, and Table 66 a reduced and condensed general summary. Table 67 gives the Transverse strength in connection with the Stiffness for the Safe working load as well as for the breaking weight: the ratio which these should bear to one another, or the "Factor of Safety," varies with the nature of the material and the character of the Strain, &c. See (880), &c.

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(336.) The application of the rules and Tables may be illustrated by examples. Thus to find the breaking weight for a beam of English Oak, 12 inches deep, 6 inches wide, and 15 feet long; we may take M, from col. 6 of Table 66 at 2272 ton; then the rule (324) becomes 122 × 6 × 2272 ÷ 15 = 13·1 tons breaking weight in the centre. Again: to find the depth of a beam of Riga Fir 10 feet long, 3 inches wide, to carry the

T

TABLE 65.-Of the TRANSVERSE STRENGTH of TIMBER, or the Value of Mr, being the central Breaking Weight of a Beam 1 inch square, 1 foot long between end bearings.

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TABLE 65.-TRANSVERSE STRENGTH of TIMBER, &c.-continued.

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TABLE 65.-TRANSVERSE STRENGTH of TIMBER, &c.-continued.

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