USEFUL PROJECTS. 



S69 



tdnvinced that the evil frequently 

 thus originates, and its preyeiitioii 

 would be in using timber previous- 

 ly well dried and seasoned. 



Since I communicated the preced- 

 ing observations relative to the dry 

 rot in timber. I have been busily en- 

 gaged in draining from 4 to 500 acres 

 of ground, and larther ideas on the 

 Subject of the dry rot have recurred 

 to me from the work I have been 

 engaged in, which may probably be 

 worthy of attention. 



Where houses are troubled with 

 damp walls, near the earth's sur 

 face, it is generally, if not univer- 

 sally, occasioned by the percolation 

 of water from the higher adjoining 

 ground, which, thus intercepted in 

 its current, attempts to follow the 

 general hydrostatic law, of elevating 

 itself, by the syphon line, to a height 

 equal to that from whence it has its 

 origin. Thus in houses differently 

 situated, we see the damp arising, 

 to varying degrees of height, on tlje 

 walls ; and those arc probably ail 

 corresponding to the height at which 

 the moisture circulates in the adjoin- 

 ing ground. At its first entrance 

 to the building, and whilst the mois- 

 ture is in smaU quantity, the exca- 

 vated pnrt of the foundation wall 

 may absorb, and gradually quit such 

 propordon ; but the excess, as is 

 generally the rase in moist weather, 

 exceeding that power, the foun- 

 dation stones arc then saturated in a 

 r\ore ra|)»d proportion than the ad- 

 joining rarefied internal atmosphere 

 can evaporate : the watery particles 

 then creep up, in degrees propor- 

 tionate to the ascent from which 

 they originally descended, excepting 

 when prevented or driven otf by 

 the superior heat of the adjoining 

 rooms; whan, in addition to the 



disagreeable damp they c.iuse, they 

 I'requentiy occasion considerable da- 

 mage to pictures, furniture, •kc. 

 Drains laid out athwart the ascend- 

 ing ground, with a wry slight de- 

 sci.'nt or fall, and made of the d'jpth 

 of one yard for each yard of ascent, 

 and from the foundafion until equal 

 to the height that such damp ever 

 rises, would, there is little doubt, 

 completely secure the house and 

 furniture from the inconveniencies 

 hitherto Sustained, and would gene- 

 rally prove an effectual prevention 

 to most cases of the diy rot, whero 

 it onn;inates in extreme moisture. I 

 am of opinion that the fungus which 

 pervades decaying wood is not the 

 tirst cause, but an attendant op the 

 peculiar state to which such wood 

 bas been reduced by prior causes. 

 The dissenjinated seeds finding a 

 proper bed, or nidu^, like to the 

 mushroom, toadstool, Sec. Hx there 

 their abode, and pervade (he mIioIc 

 substance, thus accelerating the se- 

 neral law of providence, which tends 

 to make all matter reproductive. 

 Cellars, or such other places^ 

 should be drained in the manner I 

 have above mentioned, by taking oft' 

 the percolating water, prior to its 

 gaining admission to, or contact 

 with, the walls; and it is probable 

 that, in most Cases, a single drain 

 will have a complete effect; it 

 would assuredly do so, if it was not 

 for the variation of the earth's inter- 

 n;W strata, which are not easily dis- 

 cernible. If attention to this rule 

 was paid prior to the building any 

 new streets or towns, it would prove 

 essentially useful. 



The society have been informed, 

 that mortar made of lime from burnt 

 chalk, is much more destructive to 

 timber than stonc-lime, or that burnt 



3 K 3 from 



