MICROSCOPIC WORK ON THE STRUCTURE OF WOOD 



By H. D. TIEMANN, 



In Charge Section of Timber Physics, Forest Products Laboratory 



XT IS remarkable that, in the present age of development of practical 

 uses from scientific knowledge, there should still remain a field of very 

 common and wide interest undeveloped in a practical manner. In the 

 knowledge of the relationship of wood-structure to its physical properties 

 and uses nothing appears to have been worked out in a complete and concise 

 form such as to be of use to the busy man. This field of investigation might 

 be better spoken of as an adjoining frontier, since it is the common ground 

 upon which the technological knowledge of the properties and uses of woods, 

 and the scientific study of the growth and anatomy of the wood substance 

 from the botanical standpoint join together. In both of these separate fields 

 an enormous amount of study has been carried on, and a great deal of 

 knowledge exists, and there has been a number of very extensive works pub- 

 lished in an attempt to cover the entire subject. Almost without exception, 

 however, where the treatise is so broad in its scope, this frontier of knowledge 

 has been narrowed down to a line or largely obscured. Such works, however, 

 are beyond the use of the busy man because of their very comprehensiveness. 

 As a rule it is the botanist who is most familiar with the anatomy or histology 

 of wood structure, while he knows but little of the processes of manufactui'e 

 of wood or of its use in framed structures. On the other hand, the manu- 

 facturer, cari)enter and engineer know little or nothing about the microscopic 

 make-up of the very material with which they are working and which they 

 have been handling most of their lives. Why is white oak more lasting and 

 better wearing than red oak, and why is the former suitable for light cooperage 

 while the latter is not? Why are firs so difficult to treat with preservatives 

 and pines so easy? Why is eucalyptus so difficult to dry? Ask questions 

 like these of the artisan or engineer and what, as a rule, can he reply? Yet 

 the answers are simple and can be clearly shown in a way to be at once com- 

 prehensible to the business man without scientific training. 



As a rule, in works discussing the properties of woods where the 

 microscopic structure is shown, it is done from the standpoint of the identifica- 

 tion of species, and little or nothing is said in regard to the correlation of 

 structure with properties and uses. 



While it is fully realized that many of the properties of wood cannot 

 be predicted nor explained from a microscopic examination of structure alone, 

 yet it is believed that much information of value would result from a sys- 

 tematic study of this kind. Already the importance and effect of thoroughly 

 drying wood for preservative treatment and the effect of steaming have been 

 demonstrated by a study of this kind, made at the Yale laboratory of the 

 Forest Service,* and the reason whv white oak is suitable where red oak is 



*In Bulletin 107 and 120 of the American Railway Engineering and Maintenance of 

 Way Association 1909 and 1910, on the "Physical Structure of Wood in Relation to its 

 Penetrability," by H. D. Tiemann. 



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