V6 ON PREVENTING "IHE DRY-ROT? IN WOOD. 



in entirely washing out ths ferraentible sap, which therefore 

 makes them much more subject to the decay of which we 

 ure treating. It may however stili be doubted, whether it 

 acts in any other way than by furnishing a disposition, which 

 requires to be called into action by tlie same cause which 

 operates in all other cases, moisture. 

 Tnsfanff^of In proof of what I have stated, I have been informed by 



tiiejrjiijjfficucy. ^^^ ^f ^^^ Y'lce Presidents, th^t in a large vat or set of vats 

 for beer, belonging to him, the staves formed of oak 2|- 

 iiiches thick, notwithstanding they were previously steeped 

 in hot water, and then thoroughly dried, in a very short 

 time undei'went the dry rot, while others in the same situ- 

 ation contl^nned unchanged five or ten times that period. It 

 is highly worthy of remark, that the outside of ihese staves, 

 which was painted, continued fourn], and that the decay 

 began ou the inside, where, from the vats being at different 

 time^ more or less filled, tliey were subject to the joint and 

 «uccessive irjfluence of moisture and air. 

 F^npc of tern. J have mentioned above, that the putrefactive fermenta- 

 ?«hith h oc- *'on cannot take place except in certain temperatures, the 

 cufs. lowest of which, according to Thomson, must be but lit- 



tle below 45 degrees of Fahrenheit's thermometer, and the 

 highest within the degree which pirodnces dryness by evapo- 

 ■ ration. The temperature most conducive to this effect has 

 . not, so far as I knovy, been ascertained, though riiuch use- 

 ful information on thiy head might be obtained from a set of 

 well conducted experiments. 

 Tlioopi- of the The following then appears to be the whole theory of the 

 4ry-rot. dry-rot; that it is a more or less rapid decomposition of the 



substance of wood, from moisture deposited on it by con- 

 densation, to the action of which it is more disposed in cer- 

 tain situations? than jn pthers ; and that tiiis moisture op^- 

 . rates ijiost quickly qn wooqj which most abounds with the 

 saccharine or fennentible principles of the sap. Let us see 

 how this theory coneaponds with the best known means 

 of prevention, and what more effectual measures it may sugr 

 gest. 

 Tnnbcr should The first point is certainly to choose timber properly 

 bc{t;llcdata felled and well dried. And here, in order to prevent the 

 >*L'li dried. ' ' Mijudicipu.» fall of large oak timber, it may be of some con- 

 sequence; 



