A Uniform System in Experimenting on Timber. 245 



moist, low-lying situation will produce, as might be expected, 

 a very different class of timber from that obtained from the 

 same species when found upon a dry and barren ridge. It 

 also appears to me, from a comparison of experiments, that 

 the closer any particular kind of tree approaches equatorial 

 regions the stronger is the timber which it produces. 

 Whether this is a general rule or not I am unable to say, 

 but it would not be unreasonable to suppose that it is so, 

 when it is recollected that the strongest timbers in the 

 world are produced in the tropics^ as witness the krangi of 

 Borneo, the ironwood of Burmah, the West Indian mora, 

 and the ironbark of Northern Queensland, 



3. Part of tree from which timber is taken. — Of the core, 

 the sapwood, and the heartwood, the latter is the only part 

 fit for practical use, and from it, of course, the specimens 

 should be taken. The butt also appears to afford timber of 

 greater density and strength than the top. In pine trees, 

 Mr. Fincham found that the pieces taken from the butt were 

 about nine per cent, stronger than those taken from the top. 

 Whether this holds true as to our own hardwoods it is 

 impossible to say, but still as it is probably a factor affecting 

 the strength of timber, the point should be noted in con- 

 nection with experiments. 



4. Length of time seasoned. — The process of seasoning 

 affects different kinds of timber in opposite ways, making 

 some stronger, others weaker. Buffon found that oak 

 timber lost strength in the course of seasoning, and was 

 accustomed to experiment upon it the third day after it was 

 felled. Mr. James Mitchell, on the other hand, finds that 

 blue gum is strengthened by seasoning, as will be shown by 

 the following extract from Baron von Mueller's Eucalypto- 

 graphia. The specimens were 7 feet long and 2 inches 

 square : — 



Length of Time Seasoned. 



Modulus of Eupture in lbs. 



8 months 



2 to 3 years 



3 years 



4 to 5 years 

 20 years 



13,270 



16,860 

 17,670 

 16,970 

 20,940 



Mr. Laslett, again, in his work upon " Timber and Timber 

 Trees," shows by experiment that the resistance to crushing 



