LIST OF ILLUSTRATIONS. 



FKiURES. PAGE 



1— i. Method of sawinsj; tost sticks -^ 



5. Stiimlardiziug tests with ca.librat.iujc springs 5 



6. Determination of relative elastic resilience 9 



7. Relation between eross-broakiug strength anil modulus of elasticity 12 



8. Relation between compressive strengtli and specific gravity 113 



SI. Variation of compressive strength and specific gravity for varying percentage of moisture 13 



10. Kolatiou between cross-ljreakiug strengtli and percentage of moisture 13 



11. Method of constructing curves of averages -3 



X2. Diagram showing the relation between strength and weight, when reduced to a standard dryness of 



15 per cent moisture. Long-leaf yellow pine 25 



13. Diagram showinsr the range of individual results, in all kinds of tests, in terms of tlie percentage of 



the average, of 430 tests on small specimens. Long-leaf yellow pine 26 



14. Relative average quality of different trees as compared with strength in cross-bre ikiug and crushing 



endwise - -7 



ir>. Results of tests on 4" by 4" sticks from log 1, tree 52, Fmiis paluslris, showing variation of strength 



acro.ss section of log 28 



ICi. Variation of strength with distance from tlie gri>und. Mean values from trees 1, 2, 3, and 4 29 



17. Metliod of chemical analysis of turpentine 37 



18. Method of distillation of turpentine 38 



11). l)istril>utiou of turiiontino in trees - '10 



20. Relationship of dill'ereut parts of same disk 11 



21. Yield of volatile oil from constant quantity of turiientine 42 



22. Diagram of detail analyses representing radial-dimeusions of test pieces in each disk Hi 



PLATES. 



I. Floor plan of test laboratory at St. Louis. 

 II. Plan of large beam-testing maehine. 



III. Plan of small beiim-testing machine. 



IV. Plan of universal (Riehle "Harvard") testing machine. 

 V. Illustration of tension and shearing tests. 



VI. Plan of columu-testing machine. 



VII. Fig. 1. Diagram showing the increase in the modulus of rupture in cross-breaking, with decrease in 

 percentage of moisture. Tree averages plotted. Long-leaf yellow pine. Fig. 2. Diagram show- 

 ing the increase in the modulus of strength at the elastic limit, with decrease in the ]>erccutage of 

 moisture. Tree averages plotted. Long-leaf yellow pine. 



VIII. Fig. 1. Diagram showing the increase in the modulus of elasticity or tlie modulus of stiffness, with 



decrease in the percentage of moisture. Tre(! averages plotted. Long-leaf yellow pine. Fig. 2. 

 Diagram showing tlie increase in the relative elastic resilience, with decrease in tln^ percentage 

 of moisture. Tree averages plotted. Long-leaf yellow pine. 



IX. Figl. Diagram showing tiie increase in crushing strength endwise, with decrease in pen-entage of 



moisture. Tree averages plotted. Long-leaf yellow pine. Fig. 2. Diagram showing thl^ increase 

 in crushing strength across the grain, with decrease in pi^rcentage of moisture. Tree averages 

 plotted. Results correspond to a distortion of 3 per cent of dejith of specimen. Long- leaf yel- 

 low pine. 



X. Fig. 1. Diagram showing the increase in shearing strength, with decrease in the percentage of moist- 



ure. Tree averages plotted. Long-leaf yellow pine. Fig. 2. Diagram showing the relation be- 

 tween strength and stiffness, when reduced to 15 per cent moisture. Tree averages plotted. 

 Long-leaf yellow pine. 



XI. Fig. 1. Diagram showing the crushing strength endwise and the specific gravity or weight, when 



reduced to 15 per cent moisture; I.ong-leaf yellow pine. Fig. 2. Diagr.am showing the absence 

 • of any material change in specific gravity, with changes in moisture, as a ri'sult of seasoning. 



Tree averagers of "green" and "dry" tiwts plotted. Long-leaf yellow pine. 



XII. Diagram showing the absence of .any geni^ral relation between tensile strength and jii^rcentage of 



moisture. Tree averages of "green" and "dry " tests plotted. Long-leaf yellow pine. 



VU 



