Determining Time Timber Was Cut. 407 



points of delivery where large numbers of ties were accumulated. 

 This led him to investigate the problem, and although the results 

 of his study do not contain anything which was not known to 

 students of wood before, yet their practical application makes 

 them of considerable interest to both foresters and users of wood. 

 His method presupposes as a conditio sine qua non that there 

 should be present in the wood a portion, no matter how small, of 

 wood containing a part of the last ring, a condition which can 

 be readily met in all hewn ties, piling, and similar material. He 

 extended his study of the differences in the structural appearance 

 of the last layer over a whole year, during which he cut a tree 

 on the first day of each month. From each tree thus cut he took 

 two disks about one inch thick from the butt and the crown, in 

 order to study the formation of the cells at different heights in 

 the tree. Since he was chiefly interested in the species which were 

 used for railroad ties, his studies were confined exclusively to 

 pine and oak. The method which he followed in preparing the 

 sections for examination was this : From each disk he cut with 

 a penknife small sections parallel to the long axis of the tree, 

 including in every case the last layer of wood near the bark and 

 placed these in water so that they should become soft and more 

 easily cut. He then obtained by means of a microtome, thin, 

 transparent cross sections of these pieces not more than the thick- 

 ness of thin writing paper, for examination under the compound 

 microscope. The last layer of wood was examined under the mi- 

 croscope, and its structural appearance in each month of the 

 year studied. As a result of these investigations Rashevsky 

 came to the conclusion that it is possible to tell from the appear- 

 ance of the cells of the last layer of wood not only whether the 

 tree was cut in summer or winter, but whether it was cut in the 

 spring, summer, fall, or winter. This he determined by compar- 

 ing the width of the last layer of wood elements with the width 

 of a similar layer of the previous year. If, for example, the 

 winter layer directly adjoining the bark appeared under the mi- 

 croscope to have a width of half an inch, and the winter layer of 

 the previous year a width of one inch, he inferred that the tree 

 was cut in the middle of winter. If, however, the winter layer of 

 the last wood appeared to have a width of about an inch, he 

 would take it for granted that the tree was cut at the close of the 

 winter. The same rule he applied to the summer layers. If the 



