25 



tension only 270 tests fell between 75 per cent and 125 per cent of the mean, wliile some fell as 

 low as 25 per cent and some were as high as 190 per cent of the mean. 



The greater nniformity of the tests in compression can be explained by the fact that in this 

 case some ten s(|uare inches were always under test, whereas in tension only about one square 

 inch was under test. 



If but a single test is to be made of timber, the compi-ession endwise gives the best indication 

 of the general value of the wood. 



Fig. 12. — Dinnruni sliowinj; tlie reliitioii lipt\v("<'ii strfiifjtli and \YeigTit 

 when ii'diici'il to ;i staiulaiil dryness dI' 1."i ]ii'1- rent nmistnrr. I,iinf;-leaf 

 yellow ])ine (I'hius jw/Mshv's). 



VARIATION IN STRENCJTH OF DIFFERENT TKEES. 



The accompanying diagram (Fig. 14), showing the variation in strengtli ol' diHerent trees, lias 



been made up from the results recorded iuTahlclli. This table gives in hold faced type the mean 



results of all tests on specimens taken from the first 20 fcH'tof the tree (butt). Tiic light-fat'ed tyiie 



gi^es the percentage which each result is of the mean of all. The average of these percentages 



14.500— No. 8 4 



