TIMBER PHYSICS — METHODS AND AIMS. ^ 379 



An authority on engineering matters writes regarding this woik: 



a Inasmuch as what passes* current among engineers and architects as information on the strength of timber is 

 really misinformation, and that no rational designing in timber can be done until something more reliable is furnished 

 in this direction, the necessity for making a competent and trustworthy series of such tests is apparent. This is a 

 work which the Government should undertake if it is to be impartial and general." 



A caieful lecord of all that pertains to the history and conditions of the growth from which the lest pieces 

 come, and of their minute physical examination, will distinguish these tests from any hitherto undertaken on 

 American timbers. 



The disk pieces will be studied to ascertain the form and dimensions of the trunk, the rate and mode of its 

 giowth, the density of the wood, the amount of water in the fresh wood, the shrinkage consequent upon drying, the 

 structure of the wood in greatest detail, the strength, resistance, and working qualities of the wood, and lastly, its 

 chemical constituents, fuel value, and composition of the ash. 



In Bulletin 6* we are introduced to the science of "timber physics" in the following language: 



Whenever human knowledge in any particular direction has grown to such an extent and complexity as to make 

 it desirable for greater convenience and better comprehension to group it, correlate its parts, and organi/e it into 

 a systematic whole, we may dignify such knowledge by a collective name as a now science or branch of science. 

 The need of such organization is especially felt when a more systematic progress in accumulating new knowledge is 

 contemplated. In devising, therefore, the plans for a systematic and comprehensi re examination of our woods it has 

 appeared desirable to establish a system under which is to be organized all the knowledge we have or may acquire 

 of the nature and behavior of wood. 



To this new branch of natural science I propose to give the name of "timber physics/ 7 a term which I have 

 used first in my report for 1887, when, in devising a systematic plan of forestry science the absence of a collective 

 name for this class of knowledge became apparent. 



While forest biology contemplates the forest and its components in their living condition, we comprise in timber 

 physics all phenomena exhibited in the dead material of forest production. 



The practical application of timber or wood for human use, its technology, is based upon the knowledge of 

 timber physics, and under this term we comprise not only the anatomy, the chemical composition, the physical and 

 mechanical properties of wood, but also its diseases and defects, and a knowledge of the influences and conditions 

 which determine structure, physical, chemical, mechanical, or technical properties and defects. This comprehensive 

 science, conceived under the name here chosen, although developed more or less in some of its parts, has never yet 

 been dignified by a special name, nor has a systematic arrangement of its parts been attempted before. It comprises 

 various groups of knowledge derived from other sections of science, which are neither in themselves nor in their 

 relations to each other fully developed. 



While plant physiology, biology, chemistry, anatomy, and especially xylotomy, or the science of wood structure, 

 are more or less developed and contribute toward building up this new branch of science, but little knowledge exists 

 in regard to the interrelation between the properties of wood on one side and the modifications in its composition 

 and structure on the other. Even the relation of the properties of various woods, as compared with each other, and 

 their distinct specific peculiarities are but little explored and established. Less knowledge still exists as to the 

 relation of the conditions which surround the living tree to the properties which are exhibited in its wood as a result 

 of its life functions. Suppositious and conjectures more or less plausible preponderate over positive knowledge 

 derived from exact observation and from the Jesuits of experiments. Still less complete is our knowledge in regard 

 to the relation of properties and the methods and means used for shaping or working the wood. 



The close interrelation of all branches of natural science is now so well recognized that I need not lemind my 

 readers that hard and fast lines can not be drawn whereby each field of inquiry is confined and limited; there must 

 necessarily be an overlapping from one to the other. Any system, therefore, of dividing a larger field of inquiry 

 into paits is only a matter of convenience ; its divisions and correlations must be. to some extent arbitrary and varied 

 according to the point of view from which we proceed to divide and correlate. 



There are two definite and separate directions in which this branch of natural science needs to be developed, 

 and the knowledge comprised in it may be divided accordingly. On one side it draws its substance largely from the 

 more comprehensive fields of botany, molecular physics, and chemistry, and on the other side it rests upon investi- 

 gations of the wood material from the point of view of mechanics or dynamics. In the first direction we are led to 

 deal with the wood material as it is, its nature or appearance and conditions; in the second direction we consider 

 the wood material in relation to external mechanical forces, its behavior under stress. 



The first part is largely descriptive, concerned in examining gross and minute -structures, physical and chemical 

 conditions and properties, and ultimately attempting to explain these by referring to causes and conditions which 

 produce them. This is a field for investigation and research by the plant physiologist in the laboratory in connec- 

 tion with studies of environment in the forest. The second part, which relies for its development mainly upon 

 experiment by the engineer, deals with the properties which are a natural consequence of the structure, physical 

 condition, and chemical composition of the wood as exhibited under the application of external mechanical forces. 

 It comprises, therefore, those studies which contemplate the wood substance, with special reference to the uses of 

 man, and forms ultimately the basis for the mechanical technology of wood or the methods of its use in the arts. 



The correlation of the results of these two directions of study as cause and effect is the highest aim and 

 ultimate goal, the philosophy of the science of timber physics. Timber physics, in short, is to furnish all necessary 

 knowledge of the rational application of wood in the arts, and at the same tune, by retrospection ? such knowledge 

 will enable us to produce ?n pup owu forest growth qualities of given character, 



