go TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



density and resistance to pressure of the wood increase regularly 

 in passing from above downwards in the trunk of the tree. 

 Before testing, all the samples were thoroughly dried in an oven 

 kept just below the temperature of boiling water. Miinch found 

 that the infected wood became slightly lighter in weight and 

 weaker with regard to compression, but he attributed these 

 effects to the presence of other wood-destroying fungi in the 

 samples used for testing, and concludes that neither the specific 

 gravity nor the resistance to compression is altered by infection 

 with Ceraiostomella. Weiss and Barnum,i in the United States, 

 have tested "blued" and normal pieces of the timber of 

 Finus palustris, and find that for all practical purposes the 

 infected wood is as strong as the healthy samples. But heavily- 

 stained timber of Finns echinata^ having the same water-content 

 as the normal, was found to be slightly weaker and showed less 

 surface hardness than the unstained. 



The experiments of Professor Hudson Beare were carried out 

 on timber of the Scots pine .obtained from Deeside, Strathdon, 

 and Inverness. The infected pieces were included amongst 

 a number of healthy samples, which were being tested to 

 determine their fitness for aeroplane construction. Only cross- 

 breaking tests were carried out on the infected wood, the size 

 of the specimens used being approximately 2x1 inch, and the 

 length 4 feet. The specimens were air-dried under cover for 

 some time before testing, and the moisture-content at the time 

 of the test was determined by drying six sections from each 

 specimen in an oven kept at a temperature of 212° F. For 

 purposes of comparison the standard moisture-content of 

 15 per cent., as proposed by Bauschinger," was adopted, and 

 the results were reduced to the standard by the formula given 

 by this investigator. 



Professor Hudson Beare states his conclusions as follows: — 

 "Taking first of all the eight specimens from Deeside and 

 Strathdon, the conclusion I formed was that the presence of the 

 fungus had a distinct tendency to lower the limit of elasticity 

 of the material, and also to reduce the modulus of elasticity. 

 The four Deeside specimens had an average limit of elasticity 

 of 2834 lbs. per sq. inch, and an average modulus of about 



^ Quoted by Hubert, I.e., p. . 



^ See W. C. Unwin, "Testing of Materials of Construction," 3rd ed., 

 1910, p. 402. 



