348 REPORT OF THE FOREST, FISH AND GAME COMMISSIONER. 



of practical forestry economics. Perhaps but few persons have considered 

 the preservation of timber from natural decay and from wood-destroying 

 animals in this light; yet it is perfectly evident that to prolong the life 

 of a piece of manufactured lumber, or of a pile, is to aid in the work of 

 perpetuating the forest quite as effectually as to guard the untouched 

 trees themselves from fire or axe. 



Poinds of Timber Hot 



The decay of manufactured lumber, and of timber and piles, may be 

 due either to dry-rot or wet-rot. 



Dry-rot may be caused by painting green, unseasoned timber, or it may 

 occur naturally, as when timber is kept in confined air, without ventilation. 

 In this case, whether or not moisture be present, dry-rot may be occasioned, 

 and the wood at last converted into a fine powder. This condition is often 

 noticed in sills and posts of old framed buildings and at the ends of joints 

 imbedded in brick and masonry walls. 



Wet-rot is the gradual disintegration and decomposition of all organic 

 matter when exposed to air and moisture, that is, alternate wetness and 

 dryness, as seen in timber lying on the ground or as exposed in a structure. 

 It also occurs in all surfaces of contact, as in the joints of timber frames 

 where the air is more or less confined and heat is developed, although 

 the degree of moisture is slight. Moisture is essential to wet-rot. This 

 form of decay is also developed in the tree while standing and growing, 

 as is often seen in hollow trees. Wet-rot is in reality the growth of bacteria 

 or fungus. 



Destructive Animal Forms 



The forms of animal life seriously destructive to commercial timber 

 may be divided into marine wood-borers and land wood-borers. There 

 are some fresh-water wood-borers, but they are very rare and their injuries 

 are generally negligible. 



Of the marine wood-borers, the common ship worm, or teredo, and 

 the limnoria, are the best known and the most destructive. The chelura 

 is of more recent discovery in this country, and the extent of its depreda- 

 tions is not vet fullv known. 



