INTRODUCTION. 5 



fewer tests for each species. So far as known most specimens were 

 from butts. Nothing is known of moisture conditions save that 

 specimens were "carefully seasoned." Tests were upon about 

 twelve hundred specimens divided over four hundred and twelve 

 species, allowing but a small number for each. The series is most 

 valuable in that the species attempted were so numerous as to present 

 an almost complete American series; in that the botanical identity 

 of the specimens was beyond question, and because it gives a general 

 idea of relative values. The results are frequently quoted and appear 

 on the accompanying pages in spaces immediately following those 

 occupied by, or set apart for, ' ' Forestry ' ' figures or their alternates. 

 The tests are characterized as follows: 



Botanical Accuracy Assured. 



Specific Gravity Determinations. 



Uniformity of Methods. 



Limited Number of Individuals and Total Tests. 



Large Number of Species Covered. 



Small Test Pieces Only. 



Selection and Moisture Conditions Indefinite. 



They are originally described in Vol. IX, Tenth U. S. Census; 

 Executive Document No. 5, Forty-eighth Congress, First Session; 

 in Catalogue of the " Jesup Collection," by Professor C. S. Sargent, 

 and elsewhere. 



(3) Experiments conducted upon full-sized pieces. The most 

 reliable investigations under this head were either csnducted by 

 Professor Lanza, of the Massachusetts Institute of Technology, or 

 else are noted by him in his work, " Applied Mechanics " (ed. 1895, 

 pp. 673-711). They are valuable in that specimens were selected 

 on a commercial rather than on a scientific basis. Professor Lanza 

 claims that such actual pieces are less perfect and show approxi- 

 mately one half the unit strength developed by the more carefully 

 selected smaller specimens. These experiments are characterized as 

 follows : 



Life-sized Specimens. 



Miscellaneous Selections as if for Practical Construction. 



Moisture and Other Data Indefinite. 



(4) All other experiments. Many experiments have been made 

 from time to time which, while valuable, are not distinguished by 

 any particular method or principle, such as separate the investiga- 

 tions noted in the preceding articles. Data as to selection of 

 specimens, moisture, and other conditions are either incomplete or 

 else absolutely lacking. Such tests are referred to as are noted in 

 works of Hatfield, Trautwein, Lazlett, Rankine, Thurston, and 

 others. Some of these series are exceedingly valuable comparatively. 

 Professor Rankine and Mr. Lazlett experimented principally upon 

 foreign woods. 



