64 TIMBER AND TIMBER TREES. [CHAP. 



In these tables are recorded the results of 108 ex- 

 periments on the crushing strains applied .to specimens 

 of English Oak timber, varying from small pieces with 

 only I inch of base, and I inch in height, carrying 

 7,978 Ibs., to larger pieces with no inches of base, and 

 21 inches in height, carrying 734,272 Ibs., or 327 tons 

 1 6 cwt, before breaking. The intermediate sizes include 

 some pieces with 36 inches of base and 36 inches in 

 height, this being the greatest length upon which I have 

 been able to bring the crushing force to bear. 



It is to be regretted that these experiments could 

 only be carried on with pieces of inconsiderable length, 

 owing to the difficulty experienced in keeping the 

 centres perfectly straight with the line of pressure. Still, 

 enough has, I hope, been done to afford a fair guide 

 for determining the scantlings for pillars to beams, &c., 

 although, perhaps, there is not even yet sufficient data 

 to construct a formula upon. 



M. Rondelet ascertained that it took a force of 

 5,000 to 6,000 Ibs. to crush a piece of Oak having 

 I inch of base ; and Mr. Rennie gives 3,860 Ibs. as the 

 force required to crush a similar piece I inch in height. 

 These two statements vary considerably from each 

 other, and also from my own experience, inasmuch as 

 I found it required a force of 7,978 Ibs., or 3*562 tons 

 weight, to crush a I -inch cube of seasoned Oak ; vide 

 Table XVI. 



In a trial, however, of six pieces of unseasoned Oak 

 of the same dimensions, it was found that it took upon 

 an average only 5,367 Ibs., or 2-396 tons one piece 

 requiring only 4,480 Ibs., or 2 tons, to crush it; vide 

 Table XV. 



The experiments upon seasoned cubes of Oak, of 2, 

 3, and 4 inches (Table XVI.) show that the force re- 



