61 
Experiments I I, L5, and LG show fclio results of boring doles for the 
spikes. Tbo .', inch hole seemed too Large; the -, 7 ( .-iiieh hole showed an 
improvement ; while the |-inch one gave the best results. 
Experiments 17 to L9, inclusive, are instructive, and correspond to 
spikes driven into dry bridge ties; showing also the increased adhesion 
gained by driving spikes tangentially to the layers of wood ; of course, 
ties ballasted would not be as dry as this timber. 
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, and 
probably above the average results ; No. 26 was in the same tie, but the 
spiko was blunt and tore the wood, leaving but little in front and back 
of the spike j such results are common in practice. Nos. 23 and 24 show 
the improvement over No. 26 gained by I >ring holes,- the adhesion was 
increased as the spike was drawn out at different lengths. 
The White Oak tie holds a spike firmly, not giving up its hold rapidly 
as it is drawn out. Boring holes increases the adhesion* and materially 
lessens the checking of the layers and injury to the wood-fibers. 
* See experiments No. 30 and 33, p. 50. 
