ADDRESS BY THE PRESIDENT, NOVEMBER 3, 1875. 15 



growing in wet and ill-drained soil are subject to rot. The more 

 abundant the alburnum or sap-wood, the more liable are trees to 

 decay. The disease which has recently attacked the larch is 

 attributed by some to the roots reaching ungenial soil, and to the 

 production of dry rot. This rot in the larch begins in the heart- 

 wood, near the root, and it spreads outwards ; layer after layer 

 crumbling like saw-dust. Among the crumbling mass is to be 

 found, in abundance, the mycelium of some fungus. When the 

 rot has reached the alburnum a thick leathery white formation 

 appears between the bark and wood, which formation is identical 

 with the appearances connected with dry rot. In dry rot the 

 decay takes place, in the first instance, in the contents of the 

 woody tubes, and thus a suitable soil is supplied for the spores of 

 fungi, such as Merulius lacrymans or vastator, and Polyporus 

 destructor. When these plants begin to grow, they spread their 

 mycelium with great rapidity. If air is allowed to circulate freely 

 around wood, dry rot does not attack it. But if it is placed in 

 a damp situation, without a circulation of air, then decay takes 

 place. The spawn of the dry-rot fungus deprives the woody tubes 

 of their contents, for the purpose of getting the nourishment it 

 requires, and the wood loses its consistency and toughness, the 

 walls of the tubes becoming brittle, and ruptured. 



The great cause of decay in wood is moisture. Wood in a dry 

 state may be preserved for a long time, as may be seen in the 

 case of wood in some old buildings, as Westminster Hall. Saw- 

 dust is wood in small pieces ; when wet it soon rots, but when 

 dried thoroughly it may be kept for an indefinite period. To have 

 timber in the driest state, it ought to be felled between the fall of 

 the leaf and the spring, the nearer the former time the bettei*. 

 The timber of some trees is much more subject to decay than that 

 of others. The wood of the cypress is very dm-able. A great 

 error in building is painting wood early, and thus enclosing within 

 it the elements of decay, by not allowing the escape of moisture. 

 In olden times the wood was left bare, and exposed to currents of 

 air which kept it dry. Hence its durability. Such is the case 

 with the roof of Westminster Hall, which dates from the time of 

 Richard the Second, and still is sound. So also the wooden roof 

 of York Minster, constructed in the thirteenth and fourteenth 

 centuries ; also the timber of the Hospitium, constructed about 

 the same period, in the garden of the Yorkshire Philosophical 

 Society. Old doors and ancient pews in village churches owe 



