105 



it intarl ami liinil\' attaclu'il to tlu' pile. Aside from slei'w |)ipc i^rotcctioiis or concrete 

 shells placed armiiid |>iles, tlu- .iriiior is usually attached to the wood by means of 

 wire or nails at a comparatively few points. Corrosion weakens these fastenings, 

 various stresses betiin to act on the se\eral parts — such as unequal expansion or con- 

 traction, wave action, shell fish and uioUusc attack in the small crevices — and rupture 

 of the protection soon I'ollows. Shed nu'lal is easily ruiiturcil and torn away; a pro- 



Fie;. 40. Driving creosoted piling. Note cap on pile under hammer to avoid splitting. 



(5. P. Co. Photo.) 



tection such as vitrified pipe will break in pieces and fall off. The homogeneous 

 character of the creosoted pile avoids all these difficulties. 



On the other hand it must be strongly pointed out that in respect to damage, if 



