. Report on the relation of railroads to forest supplies and forestry : together with appendices on the structure of some timber ties, their behavior, and the cause of their decay in the road bed, on wood preservation, on metal ties, and on the use of spark arresters . pression produced in driving the spike lubricates the latter so that theadhesion is not as great as it should be according to the specific gravityof the wood; and after the spike is started the adhesion decreases rap-idly. This feature has been noticed when the rails are raised up onthick shims, the spikes holding but little in
. Report on the relation of railroads to forest supplies and forestry : together with appendices on the structure of some timber ties, their behavior, and the cause of their decay in the road bed, on wood preservation, on metal ties, and on the use of spark arresters . pression produced in driving the spike lubricates the latter so that theadhesion is not as great as it should be according to the specific gravityof the wood; and after the spike is started the adhesion decreases rap-idly. This feature has been noticed when the rails are raised up onthick shims, the spikes holding but little in the ties, and being easilydisplaced. The fibers of the wood are broken and bent down, so that they do notclose up tightly to the body of the spike, as in Chestnut and Oak ties. * Seo Figs. 1 and 2, p. 61. 61 Experiments I I, L5, and LG show fclio results of boring doles for thespikes. Tbo ., inch hole seemed too Large; the -,7(.-iiieh hole showed animprovement ; while the |-inch one gave the best results. Experiments 17 to L9, inclusive, are instructive, and correspond tospikes driven into dry bridge ties; showing also the increased adhesiongained by driving spikes tangentially to the layers of wood ; of course,ties ballasted would not be as dry as this Fig. 2. Longitudinal section of a portion of a tie showing the effect of driving a spiko. White Cedar gives the most irregular results. No. 22 is good, andprobably above the average results; No. 26 was in the same tie, but thespiko was blunt and tore the wood, leaving but little in front and backof the spike j such results are common in practice. Nos. 23 and 24 showthe improvement over No. 26 gained by I >ring holes,- the adhesion wasincreased as the spike was drawn out at different lengths. The White Oak tie holds a spike firmly, not giving up its hold rapidlyas it is drawn out. Boring holes increases the adhesion* and materiallylessens the checking of the layers and injury to the wood-fibers. * See experiments No.
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Keywords: ., boo, bookcentury1800, booksubjectforestsandforestry, bookyear1887
