868 



ANNUAL REGISTER, 1805. 



snre. To bring the matter to the 

 test by experiments would require 

 the observation of a long period, 

 and in selected situations. 



Wood used for the general pur- 

 poses of man, is cut down at dilfer- 

 ent periods ; and although it may 

 Le felled at the proper season, or 

 ■when most free from sap or mois- 

 ture, it is not always to be effected. 



Even admitting it to have been 

 cut down in the most favourable si- 

 tuation, it still abo'inds with such 

 an extra proportion of moisture, as 

 to require a regular exposure to the 

 air, prior to its being applied to use, 

 if we wish to guard against that 

 shrinking, which always takes place, 

 ■jvhere this precaution has not been 

 taken. 



Altliough the fir kind contains 

 less of this watery portion, yet it 

 assuredly possesses a considerable 

 share ; and it is in this species, I 

 apprehend, that the evil called the 

 dry rot most generally occurs, as 

 irom the facility of working the 

 same, it is most generally applied in 

 buildings. 



But supposing it to be fir, or any 

 other species: wood felled when 

 abounding with any extra propor- 

 tion of sap, and applied to use with- 

 out the proper seasoning or expo- 

 sure to a free current of air, until 

 such extra moisture has had time to 

 cxhale,is most liable to the disease in 

 question ; aiul the cure, or principal 

 prevention against it. Mould be the 

 precaution of felling all wood only 

 at the proper season, or when the 

 sap is not in circulation. The next 

 mode of preventioQ would be to use 

 such wood only, as has been for a 

 considerable period exposed to the 

 influence of a free current of air, or- 

 where convenience will admit, to 



that of air heated to a moderate de- 

 gree ; such air extracting with great- 

 er facility the inclosed moisture, 

 and in a more certain ratio than the 

 irregularity of our atmosphere will 

 allov.-. 



In all rapid! y improving countries, 

 this evil is likely to be an increasing 

 one, as the current demand for wood 

 generally exceeds the supplies laid by 

 in store, so as to be applied to use 

 in regular succession, after being 

 properly seasoned Another cause 

 that aliects all wood most materially, 

 when not fully dried, is the applica- 

 tion of paint, the nature of which 

 prevents all exhalation, and confines 

 the enclosed moisture, till it occa- 

 sions a fermentation through tho 

 whole iibrous system of the wood, 

 aiid brings on a premature state of 

 decomposition, or the dry rot. 



A similar evil may be induced, in 

 consequence of any newly finished 

 building having all the doors and 

 windows shut up, and that for some 

 length of tiiiie, particularly in moist 

 weather. The wood, even though 

 unpaintcd, is thus frequei\tly placed 

 in an atmosphere more charged ^ith 

 vapour than its own internal con- 

 tents, and is consequently in an im., 

 bihing instead of an exhaling state, 

 and tending to decay. Wood 

 placid in dani|;isli situations, and the 

 ends of limbers near to moist walls, 

 surfer from similar causes. 



What particularly attracted my 

 observation to thecircutustances was 

 this, that both ash and fir posts 

 were brought into this prcniatnrt> 

 state of decay, froci their having 

 been painted prior to the due cra- 

 poration of their moisture : and then 

 extotiding the observation, and 

 tracing the history of other wood 

 affected in a similar manner, I am 



convince^ 



