830 On Preventing the Decay of Wood, 
In proof of what I have stated, I have been informed 
by one of our vice presidents, that in a large vat or set of 
vats for beer, belonging to him, the staves formed of oak 
two inches and a Jtialf thick, notwithstanding they were 
previously steeped in hot water, and then thoroughly 
dried, in a very short time underwent the dry rot, while 
others in the same situation continued unchanged five or 
ten times that period* It is highly worthy of remark, 
that the outside of these staves, which was painted, con- 
tinue d sound, and that the decay began on the inside, 
where, from the vats being at different times more or less 
filled, they were subject to the joint and successive influ- 
ence of moisture and air. 
I have mentioned above, that the putrefactive fermen- 
tation cannot take place except in certain temperatures, 
the lowest of which, according to Thomson, must be 
but little below 45 degrees of Fahrenheit’s thermometer, 
and the highest within the degree which produces dry- 
ness, by evaporation. The temperature most conducive 
to this effect has not, so far as I know, been ascertained^ 
though much useful information on this head might be 
obtained from a set of well conducted experiments. 
The following then appears to be the whole theory of 
the dry-rot; that if is a more or less rapid decomposition 
of the substance of wood, from moisture deposited on it 
by condensation, to the action of which it is more dis- 
posed in certain situations than in others ; and that this 
moisture operates most quickly on wood which most 
abounds with the saccharine or fermentible principles of 
the sap. Let us see how this theory corresponds with 
the best known means of prevention, and what more ef- 
fectual measures it may suggest. 
The first point is certainly to choose timber properly 
felled and well dried. And here, in order to prevent 
the injudicious fall of large oak timber, it may be of some 
