24 



Bauscliins'er tbiiiid that wintci-felled wood of these couifers was lT) per eeut stionger than the 

 summer felled, if they are both used immediately after felliug, but that this difference passes away 

 with seasoning. Heclaims a direct proportion between strength and density (or weight of the dry 

 liber), which he ventures to formulate thus: 



Crushing strength per cubic inch = 6.35 D - 0.635, where D denotes density of wood with 15 per 

 cent moisture, calculated upon the dry wood. He considers crushing tests, using test pieces 6 

 inches high, as the most satisfactory for tiudjer. 



Altogether the work of Bauschinger ranks as one of the best and most caretiil researches in 

 this direction, and has to some extent served as a basis for the work now proposed on American 

 timbers. Further illustrations of the results of Bauschinger's work will be found further on in this 



bulletin. 



Although not undertaken for the ]iuri)osc of determining any relation of mechanical and phys- 

 ical properties of timbers, we may here mention, on ac.'ount of careful methods, the tests performed 

 by David Kirkaldy, of Loudon, commented upon in an interesting publication entitled Illustra- 

 tions of David Kirkaldy's System of Mechanical Testing, by Wm. G. Kirkaldy, 1891. 



It is interesting and gratifying to note liere that almost simultanecmsly, but without knowledge 

 of the fact, both the Governrae"nts of Prussia, and of the United States in the present proposed tim- 

 ber investigations conceived the necessity of more careful, painstaking, and comprehensive work in 

 timber physics than has been attempted before. 



With the careful and circumsi)ect manner which chanuterizes all tlic (loverument work of 

 Prussia, before engaging fully ui)on the main work, a ])reliminary investigation into methods was 

 determined upon in 1884, when a special conimission was charged by the Minister for Agricultuie, 

 Public Lands and Forests to determine upon a working jilan. 



The results of this preliminary investigation, in which three pine trees were most carefully 

 investigated, were published in 1889 as. a report by M. Kudeloft', first assistant of the Eoyal Tech- 

 cal Exi>eriment Station, at Berlin. IJi)ou the basis of this investigation a plan for the executiou 

 of the principal work has been elaborated. Although this preliminary work was not known to the 

 writer when devising similar work for Ameri<-au timbers, it appears that in the main the working 

 plans resemble each other closely with the one exception, namely, that the need of i)ractically 

 applicable results has here been kept in the foreground. We have not spent time to arrive at sat 

 isfactory methods befoi'c proceeding to the main work, but expect to improve the methods as the 

 work i)roceeds, meanwhile accunuilating valuable and useful data. 



In regard to the mechanical properties which adapt wood to building, construction, and engi- 

 neering purposes generally, there exists since (Ihevandier and Wertheim a considerable, rich, and 

 varied mass of results of experimentation. We hare, hoirerct; hardhj Jhiinil vioir thun the meth- 

 ods of investigation and a few examphs to illustrate them. To satisfy scientife inquin/ more fully 

 will require a considerable amount of mental and peeiiniari/ effort, ahieh should be si/stenuitiealli/ ear- 

 ned on after a well-dinested plan like thai now inaugurated in the Forestry JUrision, and not be 

 dependent on aevidental opportunity. 



The knowledge of other groups of properties is in some respects still further removed fi-om 

 the goal that it is desirable to reach. The least has bec'n done with regard to the scientific develop- 

 ment of technology. While Habtig, at Dresden, has taught how to test wood- working machines 

 with reference to their effectiveness, nobody yet has tried to determine quantitatively the working 

 (pialities of wood in such a manner that the expenditure of energy necessary in t heir working could 

 be determined beforehand; nobody has yet discussed the connection of these degrees of quality 

 with the mechaiucal and physical properties and with the structure and chenustry of wood. 



Carl KARMAi!sii,the celebrated technologist, who raised descriptive technology to tlic rank 

 of a science, laid the foundation for the discussion <if all technical jiroijerties which stand in rela- 

 tion to the working and use of wood in the industries in his celebrated stantlard work, Han(ll)uch 

 der mechanischeu Technologie (Handbook of Mechanical Technology), 1st ed., 1837; 5tli ed., 

 187."); last edition, enlarged by II. Fisher in 188S. In this work elasti<'ity and even strength are 

 considered of less moment than density, hardness, deavability, change of volume, which are of so 

 much account in shaping and in keeping in shape wood structures. The main merit of his work 

 lies in the comprehensive representation of all the reliable old and new data and in bringing to- 



