152 THE AMERICAN BOTANIST 



but flowers with green rays were not rare. The green rays 

 were about half the length of the yellow rays of the ordinary 

 flower. A green flowered yellow daisy is a very noticeable plant ; 

 as plants producing conspicuous green flowers are rather unusual 

 in our floras. This pasture is near where this western plant 

 was introduced about 1856. Hundreds of typical plants were 

 in bloom in this field. Among the plants, were found occasion- 

 ally, flowers with a double row of orange-yellow rays. — 

 Stewart H. Burnham. 



Strength of Wood. — One of the earliest relations which 

 foresters have established with a fair certainty is that between 

 the specific gravity of wood and its technical qualities. Some 

 foresters even go so far as to claim that the specific gravity of 

 wood is an indicator of all other mechanical properties and that 

 the strength of wood increases with the specific gravity irre- 

 spective of the species and genus. In other words the heavier 

 the wood, all other conditions being equal, the greater its 

 strength. Even oak, which apparently formed an exception, 

 has been recently shown to follow the same law. If there is 

 still some doubt that the specific gravity of wood can be made 

 a criterion of all mechanical and technical properties of wood, 

 the correlation between the specific gravity and the resistance 

 to compression endwise (parallel to the grain) is apparently 

 beyond question. The compression endwise equals 1,000 times 

 the specific gravity minus TO. One of the other properties of 

 wood, namely, hardness, was found to have a definite relation 

 to the bending and compression strength of wood and this fact 

 tempts to the conclusion that by hardness alone all other me- 

 chanical properties can be determined. Hardness was also 

 found to have a definite relation to the proportion of the 

 summerwood in the annual ring, and consequently to the 

 specific gravity of the wood. — Henry S. Graves in Journal of 

 the Washington Academy of Sciences. 



