rt would be impossible to estimate the direct and indirect losses \Yhich the country suffers from 

 our ignorance as to the true values and strength of our building timbers. Such losses occur by 

 using kinds unsuited for given purposes, or by emi)loying either more or else less timber than 

 necessary. Engineers and architects are fully aware of this defi(;iency in our knowledge, which 

 approaches "a state of ignorance" remarkable to contemplate when it is considered that timber 

 has always been a foremost building material. 



To make good this assertion a resumd of some hundred letters received by the Department from 

 leading engineers, scientific societies, and others is appended to this report, which, while strongly 

 i;ivorin<^ the thorough investigation of our timbers, are of interest also as showing the multiplicity 

 of directions in which the work would be of benetit. 



Not only are our engineers' tables, giving values of strength, uncertain, uureliable for practical 

 use, i)ascd n\mu European timbers, etc., but probably not one in a hundred engineers or architects, 

 who specifies timber for work, is capable of determining whether a given stick of timber is or is not 

 capable of doing the duty it is designed to do. Even if he recognizes the species of timber, which 

 he rarely can do with accuiracy, he would fail to recognize any relation between the appearance or 

 structure of the material and its expected or desired quality. And if he be better informed than 

 the majority it will be only through dearly-bought experience. Empiricism in this branch of 

 engineering still reigns supreme. 



It is only six years ago that Prof. Lanza showed that tests made on small specimens, and on 

 which our tables for engineers' use are based, may give results more than twice as high as those 

 made on full-sized sticks; and although a factor of safety of 4 may have been applied in the speci- 

 fication, when it is found that material may have actually a strength .50 per cent less than that 

 <>iven in the tables, we may often strain our material, without knowing it, to its full capacity and 

 feel safe in so doing. 



The following statement, which occurs in one of the letters referred to, may serve as an illus- 

 tration. Mr. D. H. Burnham, engineer of construction for the World's Columbian Exposition, 

 writes : 



When I was apijointed ougiucer of coustniction, Woilil's Columbian Exposition, August 1, I found it necessary to 

 make changes in most of the biiililings because I (lid not dare to use as high u-iit stress in timber as was used by my 

 predecessor, aUliougli he claimed to be perfectly safe in his strains, and brought forward authorities— Trautwine and 

 others — to ]ir<)ve his statements. 



Inquiries from woodworkers in all branches show that the same lack of reliable knowledge exists 

 with regard to the adaptation of woods to technical purposes. Especially are the ideas as to the 

 relation of properties to structure, physical condition, h)cality of growth, etc., entii-ely at variance 

 and lacking a sound basis derived from accurate observation and research. It would then appear 

 that from a practical point of view the need for an investigation exists, the more so since our forest 

 resources begin more decidedly to show the signs of lavish wastefulness, and proper economy 

 would dictate a more careful employment of our wood materials. 



Lastly, since we are beginning to plant forests and since forestry does not concern itself with 

 the production of wood simply, but is to produce wood of given quality, we need this knowledge 

 in order to proceed intelligently in the selection of plant material with reference to local ily and 

 in order to be able to control in a measure the quahty of the product. 



It is of interest to inquire why our ignorance exists and has prevailed so long, and to lind out 

 what is necessary in order to remove it. 



There is one important factor of difference between other materials of construction and timber. 

 It is the factor of life. Life means variety, change, variability. Each individual differs from every 

 other in its development, and each part of the individual differs from its other parts in structure, 

 and hence in qualities. Each living tree of the same species, therefore, converted into building 

 material offers a different problem as to its properties, especially its strength, and each stick taken 

 from a ditlerent part of the tree shows different quality. 



This endless variability it is that has kept us in ignorance as to the capabilities of oiu- timbers. 

 While, by experience, we have learned that these differences exist, and even learned to find some 

 relations between physical appearances, anatomical structure, and mechanical properties, the enor- 

 mity of the enterprise has battled investigators ami deterred them from carrying on, in a systematic 



