Page:Professional papers on Indian Engineering (second series).djvu/241

 No. CCCII.

REPORT ON EXPERIMENTS MADE AT LUCKNOW ON STRENGTH OF SAL AND TEAK TIMBER, IN 1877 AND 1878.

By Capt. J. DUNDAS, V.C., R.E., Assistant to Inspector General, Military Works.

EXPERIMENTS made in the Panjab having shown that the recorded con- stant coefficients ordinarily used in calculations of the transverse strength and stiffness of deodar timber were too large* to give correct results in the case of seasoned beams of some size, the question was raised whether the constants commonly used for sal and teak timber might not be found on trial to be equally untrue. Instructions were accordingly given for a series of experiments to be made at Lucknow, under the conditions stated below. (a). On 12 pieces of seasoned sal wood; each piece 12 feet long and 6" x 4" scantling. (6). On 12 pieces of seasoned teak wood; of the same dimensions. (c). On 12 pieces of seasoned sal wood; each piece 30 inches long and 1 inch square. (d). On 12 pieces of seasoned teak; of the same dimensions. The distance between the supports to be 10 feet in the case of the larger scantlings, and 2 feet in the case of the smaller ones. The load to be applied at the centre. About ab of the calculated breaking weight to be first applied and to be left on for 7 days. The deflection at the centre to be then carefully measured in inches and decimals. • The experiments showed Eg = 1,800, instead of the usual 3,500. pb = 300, 153 500. D 29