378 FORESTRY INVESTIGATIONS U. S. DEPARTMENT OF AGKICULTl 



development of the investigation and its methods was not published until I .ullctin fi, in 



which Mr. Fernow described the aims, objects, and methods at length. 

 In the report for 1890 the following language is used: 



TIMBER TESTS. 



While the use of wood pulp and other substitutes may displace in many ways the use ot ood in its natural 

 state, there will always be desirable qualities inherent in the latter that make its u.sn In , . Hence the 



desirability of knowing the qualities of our Umbers and, if possible, of knowing the condit: nmier which the 

 wood crop will develop the desirable qualities. 



Much work and useful work is done in the world by the rule of thumb. All such wori not reliable and 

 certainly not economical. With the need of greater economy in production, the need of moi < urate measuring 

 arises, and with that the need of more specific knowledge of the materials to be measured. 



Wood is one of the materials which has been measured by the rule, of thumb longer tha others. Iron and 

 other metals used in the arts have their properties much more accurately determined than wood n i rial. Especially 

 in the United States, when we speak of quality of our timbers, it can only be in general terms; \\ ack definite data. 



One difficulty in determining reliably the qualities of our timbers lies in the fact that livir things are rarely 

 precisely alike. Every tree differs from every other tree, and the material taken from the one hi a different value 

 from that taken from the other of the same species. Yet every tree has some characteristics < ommou with all 

 those grown under similar conditions. But even these common properties differ in degree in d: rent individuals. 

 Individual variation tends to obscure relationship. 



The factors which determine the quality of timbers are found directly in the structure of i \\ood, and it is 

 possible from a mere ocular examination to judge to some extent what qualities may be expeetedrom a given piece 

 of timber, although even in this direction our knowledge is very incomplete, and but few detinii Nations between 

 structure and quality, or between physical and mechanical properties, are established. We kno that the width of 

 the annual rings, their even growth, the closeness of grain, the length, number, thickness, and istribution of the 

 various cell elements, the weight, and many other physical appearances and properties of the nod influence its 

 quality, yet the exact relation of these is but little studied. Conjectures more or less plausible, npositions, and a 

 few practical experiences preponderate over positive knowledge and results of experiments. A u we know, in a 

 general way, that structure and composition of the wood must depend upon the conditions ot -oil, climate, and 

 surroundings under which the tree is grown, but there are only few definite relations establishc We are largely 

 ignorant as to the nature of our wood crop, and still more so as to the conditions necessary fo.roduce desirable 

 qualities, and since forestry is not so much concerned in producing trees as in producing quality i trees, to acquire 

 or at least enlarge this knowledge must be one of the first and most desirable undertakings in v. ich this Division 

 can engage. 



Accordingly .a comprehensive plan has been put into operation to study systematically 01 more important 

 timber trees. 



It will at once be understood that as long as the qualities are to be referred to the conditioi -mder which the 

 tree is grown, the collection of the study material must be made with the greatest care, and tli aierial must be 

 .accompanied with an exhaustive description of these conditions. Since, further, so much individi . variation seems 

 to exist in trees grown under seemingly the same conditions, a large number must be studied in rder to arrive at 

 reliable average values. For the present it has been decided to study the pines, especially the v. .ie pine and the 

 three Southern lumber pines. 



In selecting localities for collecting specimens, a distinction is made between station and siti 



By station is understood a section of country (or any places within that section) which is . iracteri/ed in a 

 general way by similar climatic conditions and geological formation. Station, then, refers mail' to the general 

 geographical situation. Site refers to the local conditions and surroundings within the station, si. as difference of 

 elevation, of exposure, of physical properties and depth of the soil, nature of subsoil, and forest rxwlitions, such as 

 mixed or pure growth, open or close stand, etc. 



The selection of characteristic sites in each station requires considerable judgment. 



On each site five full-grown trees are to be taken, four of which are to bo representative anrage trees; the 

 fifth or "check" tree, however, should bo the best developed tree that can be found on the site. ; omc additional 

 test trees will be taken from the open and also a few younger trees. The trees are cut into varying iigths, and from 

 each log a disk of fi-iuch height is secured, after having marked the north and south sides and nof.i the position of 

 the log in the tree. 



The disks are sent for examination of the physical and physiological features to the Michigan iiiversity, while 

 the logs, and later on special parts of the disks are to be sent to the test laboratory of the Wash-ton I'niverslly 

 of St. Louis. Here, for the first time, a systematic series of beam tests will be made and compared ith the tests on 

 the usual small- laboratory test pieces. Such tests with full-length beams in comparison with tesl-oii small speci- 

 mens promise important practical results, for a few tests have lately developed that large timbers win to have but 

 little more than one-half the strength they were credited with by standard authorities, who relied imn the tests on 

 small specimens. 



From the " check " tree mentioned before only clear timber is to be chosen, in order to ascertainhe possibilities 

 of the specks and also to establish, if possible, a relation between such clear timber and that, <ed in general 

 practice, where elements of weakness are introduced by knots and other blemishes. 



