ioo Forestry Quarterly. 



not to have as in any other business 4.5%, but less. It is custom- 

 ary to assume a 3% rate in forest calculations but really a con- 

 stant interest rate has no justification in any business. (Yet in 

 life insurance the calculations are made on an assumed constant 

 interest rate. — Rev.) 



The author then concludes that an orderly forest management 

 which furnishes satisfactory material for the arts is possible only 

 for a people that has reached a stable civilization and has enough 

 idealism to see in the forest more than a certain quantity of wood. 

 It has taken much denial to bring for instance Prussia's forests to 

 the present status admired by other people. All that forestal 

 statics has done so far, has been simply "to open our eyes, that 

 we cannot find any management which will bring a high interest 

 rate on the capital involved. A large margin from forest prop- 

 erty can be made only by a purchaser who cuts everything that 

 pays and puts it into cash." 



The state alone can afford to manage for the interest of the 

 future. 



Zur Wiirdigung der forstlichen Statik. Forstwissenschaftliches Cen- 

 tralblatt, 1908, pp. 432-448. 



UTILIZATION, MARKET, TECHNOLOGY. 



Mr. H. D. Tiemann, in a paper read before 



Time the American Society for Testing Materials, 



Tests presented some results of his investigations 



of upon the effect of speed of testing upon the 



Strength. strength of wood. The author points out 



that the rate of strain, and not the rate of 



stress usually employed, should be used as the basis for strength 



tests, since the rate of strain can be controlled while the rate of 



stress cannot be determined in advance. He finds that the 



strength of wood varies with the speed at which the stress is 



applied, increasing more rapidly as the speed increases ; that wet 



or green wood shows much more change in strength than dry 



wood. The speed strength modulus is the ratio of the relative 



change in strength to the corresponding relative change in speed. 



