396 NOTES ON DOCKS AND DOCK CONSTRUCTION. 



Crushing strain of timber usually used for piles 



Beech ... G, 100 Ibs. 011 the square inch. 



Fir red pine 5,375 to G,200 Ibd. 



Larch ... 5, 570 Ibs. 



English oak 10,000 Ibs. 



Elm ... 10, 300 Ibs. ! 



Formula for determining the supporting power of piles. 



! 2 . S 2 . X* 2.6.8.X 



Rankine P = 





I I I 



The factor of safety against sinking is from 3 to 10, whilst 

 against crushing it should not be less than 10. 2 



Stavelly 3 and Weisbach appear to give the same formula 



w h w 2 x h 



ELEVATION 

 FIG. 348. 



FIG. 319. 



In using this formula, the Dutch engineers adopt a coefficient 

 of from 6 to 10. 4 



Major Saunders's formula is more simple and more readily 

 applicable to practical work. 



w X h 



P = 



8 X x 



The result being the safe working load on the pile. 5 



1 Rankine's "Rules and Tables," p. K8. 



2 Raukine's " Civil Engineering," 2nd ed., p. G04. 

 * Stevc-nson's "Harbours," 2nd cd., p. IbLJ. 



4 M.P.I C.E., vol. xlii. p. 216. 



4 Journal Franklin Institnlr, 3rd series, vol. xxii. p. 304; and 

 Tol. xxvii. p. 307; vol. xxxii. p. 100. 



