744 EXPERIMENT STATION RECORD. 



wood material which cau lie thoroughly and uniforinly dried, such as carriage 

 stock, cross-arms for telegraph poles, etc. The author states that the- designs 

 of structures should be based on the unit strengths which have been derived 

 from actual tests of large sticks in the condition in which they are to be used. 



Drying was found to produce a remarkable increase in the strength, stiffness, 

 and elastic limit of the wood. The effect of dryness upon the shearing strength 

 parallel to the grain is a variable quantity which can not be relied on. .Soaking 

 in cold water does not diminish the strength of the wood beyond the point at 

 which the wood fiber becomes saturated. This point the author calls the fiber- 

 satui-ation point, which is described in substance as follows : Upon immersing 

 a piece of dry wood in water the water is gradually drawn into the pores and 

 also absorbed by the walls of -the wood substance. As the latter absorbs more 

 and more water the strength continues to decrease luitil the point is reached 

 where the walls are saturated and will hold no more. This is the fiber-satura- 

 tion point and although more water may be taken iip by the pores the strength 

 of the wood does not diminish beyond this point, which may also be termed the 

 point at which swelling ceases. Heating the water, however, gradually reduces 

 the strength, since the wood fibers become more fully saturated. Wood that 

 has been dried and remoistened is weaker than wood of an equal degree of 

 moisture which has not been dried. This weakened effect is most marked in 

 the case of steaming at high pressure and is less obvious where the wood is 

 dried slowly at a low heat. 



In the introduction to the bulletin W. K. Hatt states, in su.bstance, that as a 

 re.^ult of these investigations there have been fully determined the factors by the 

 use of which the results of tests at different degrees of moisture may be reduced 

 to an equal basis in the case of certain species and certain kinds of tests, thereby 

 establishing a percentage of moisture at which the cell walls ai-e saturated in 

 the case of these species, and determining the true nature of the law represent- 

 ing the etTect of any further reduction of moisture on the strength of timber. 

 The subsidiary studies in connection with the work, such as casehardening, pro- 

 longed soaking, and soaking followed by drying, are believed to have direct 

 application to the technology of various products and to be of great value to 

 students and engineers. 



Two appendixes follow the main subject-matter. Appendix A treats of the 

 formulas used in the calculations and describes special studies and subordinate 

 investigations in connection with the work. Appendix B is a discussion of the 

 microscopic study of the fractures produced in the woods by the various tests. 



Mechanical tests, properties, and uses of thirty Philippine woods; Philip- 

 pine sawmills, lumber market, and prices, R. Gardner {[Pfiilippine] Bur. 

 Forrisiry Bui. -'/, pp. 69). — This bulletin was prepared to meet inquiries concern- 

 ing the Philippine woods and milling operations in the Philippines. Tabulated 

 data are given showing the results of tests in cross bending, compression, shear 

 tests, and moisture determinations. These results are also illustrated by several 

 linear curves. The different species tested are discussed as to their structural 

 qualities, appearance, uses, in-ovinces leading in production, sizes, and common 

 and botanical names. 



Part 2 gives an account of the present condition of the sawmill industry in 

 the Philippines, together with a discussion of the lumber market and prices. 



Wood production and commerce in Europe, Africa, and North America, 

 .7. Makchet (HolzproduktUni uiid HolzhandvJ von Europa, Afrika, uiid Nord- 

 Amcrika. rienna: W. Frick, 1905, pp. J, 59). — Statistical data are given show- 

 ing the timber production of different important timber-producing countries of 

 the world for a number of years up to 1904. and in many instances of the timber 

 imports and exports of the different countries. 



