TIMBER PHYSICS. 



INTRODULTOKY. 



The progress report liercwitli presented on the work of timlier investigations is published 

 iu less complete form than had been eontciuplated, in order to avoid longer delay in brini;ing resnlts 

 before tlie public. The delay is occasioned by inadequate apiJiopriiitions for the work; and since 

 the work is now to be stopped entirely for lack of funds, it was thought best to publish what 

 lesultswere in such shape as to present valuable information. 



The data contained in the report refer altogether to the timber of long-leaf pine (1'. palustris) 

 from Alabama, being the results of mechanical tests obtained in the test laboratory under direc- 

 tion of Prof. J. B. John.son at St. Louis. These data refer to over 2,(t()0 tests on material furnished 

 by twenty-six trees collected from fonr different sites by Dr. Cliarles Molir. 



These tests inay be said to represent fairly well the range of strengtli pertaining to the 

 species, unless unexpected differences are found in the material collected from other climatic sta- 

 tions. Such material has been collected from Louisiana and Texas, but the hick of funds mentioned 

 before has prevented its utilization for this report. 



The following table represents the range of value of tlie various exhibitions of strength as 

 compiled from Table I of Prof. Johnson's report: 



Coiidcnxrd hibh' of iiiirJiiniicdl properties of Loiuj-lcaf I'inc. 

 [Kaii^r.s rccUici'd to 15 per ct-lit iiioiBturo. ] 



Prof. -Tohnson has attempted to relate the values of strength to other qualities, especially 

 moisture contents of the test piece, and compared the various exhibitions of strength with each 

 other, t« find if possible their relation. It is to be understood that tliis di,scussiou refers only to 

 the species in hand, and does not a<lmit of generalization to other timbers. 



Some of the deductions for the long leaf pine may even have to be modilied upon further 

 study. We summarize the more important deductious as foUoiii's: 



(1) With the exception of tensile strength, a reduction of moisture is accompanied by an 

 increase in strength, .stiffness, and toughness. 



(H) Variation in strength goes generally hand in hand with variation in sjiecitic gravity. 



(3) The strongest timber is found in a^ region lying between the pith and the sap at about one- 

 third of the radius from the pith in the butt log; in the top log the heart ptu'tion seems strongest. 

 The difference in strengtli in the same log ranges, liowever, not over 12 per cent of the average, 

 excei)t in crushing across the grain and shearing, where no relation according to radial situation 

 is apparent. 



