Periodical Literature. 22/ 



It is not easily found; usually in the mountainous regions^ on south- 

 ern exposures, on dry, stony, shallow soils. Conifers do no produce 

 any suitable wood. 



Die Verwendung von Faulhoh. Schweizerische Zeitsehrift fiir 

 Forstwesen. June, I906, pp. 173-176. 



In a more or less exhaustive, highly inter- 



Hardness esting discussion, Janka reports the results 



of of a series of tests made at the Austrian Ex- 



JVood. periment Station on the hardness of wood. 



It was not so much the object of the tests 

 to establish a scale of hardness of a large number of woods, although 

 some 27 woods were tested, as to find a suitable method of testing 

 and to determine the influence of various factors on hardness, nota- 

 bly moisture and specific weight. The author refers, somewhat crit- 

 ically, to preceding work on the same subject, to Nordlinger's scale, 

 based on mere judgment, copied in all books, and points out the de- 

 ficiency in method of Biisgen's determinations with a pin (briefed 

 and criticised in Forestry Quarterly^ Vol. II, No. -i, p. 232). He 

 defines hardness as the resistance which a body opposes to the pene- 

 tration of another body between its molecules. Practically, in speak- 

 ing of hardness of wood, we think of utensils used in shaping wood, 

 but it is evident that axe, adz, hatchet, wedge, knife, chisel, plane, 

 saw, rasp, file, each work in a very different manner upon the wood 

 substance and test different combinations of strength factors; more- 

 over, the use of the instrument by either thrust or push or pressure 

 or drawing and the rapidity with which they, are moved, influence the 

 exhibition of relative hardness. It would, for practical use, appear 

 necessary to make tests with each of these tools and conditions. To 

 establish a general scale of relative hardness, however, an indenta- 

 tion test must suffice, and in such a test the form of the indenting 

 body or piece is most essential. 



The method used in this work was an adaptation of one designed 

 by Brinell for testing hardness of steel, namely by using as indent- 

 ing piece the half of a steel ball of 1 cm.^ largest circle (r = 5.6-12 

 mm.), which is pressed into the test piece to its full depth, when the 

 mere reading of the pressure gives the relative hardness. The test 

 pieces were 2.5 cm. thick and 10 cm. square, the surface divided in 9 

 squares, and each square was tested to secure an average, and in the 

 comparative tests care was taken to test pieces of the same struc- 

 ture. 



