458 Inquiries relative to the Structure of Wood. 



From a comparison of these results it appears that 

 these woods, when exposed to the air at a temperature 

 of 45 F., contain twice the quantity of water that they 

 do when the temperature of the air is at 60 F. But it 

 is necessary that the wood be cut into very thin shav- 

 ings, to enable it to become suddenly in equilibria with 

 the air, conformably to its quality of a hygrometric 

 body ; otherwise the state of the air may change, and 

 that very frequently, before its humidity or dryness can 

 have had sufficient opportunity to produce all its effect 

 upon the wood. 



To discover what is termed the medium dryness of any 

 species of wood, in our climate, it is requisite that we 

 be acquainted with the quantity of water contained in 

 wood every day of the year, and even in every hour and 

 every minute, which is obviously impossible ; but there 

 is another method to be pursued in this inquiry, much 

 less laborious and which will lead to results as satisfac- 

 tory as the nature of the subject will admit. 



As a very large piece of wood, a large beam for in- 

 stance, dries so very gradually in the air as not to attain 

 a state of perfect dryness in less than 50 or 60 years, it 

 is sufficient to examine the interior of such a beam, after 

 having been sheltered for 80 or 100 years from the rain, 

 to discover the state of such part of the wood as may 

 still be considered sound. 



In pulling down old houses, we meet with beams 

 proper for the present inquiry. 



An old castle in my neighbourhood being pulled 

 down, I had an opportunity of examining the interior 

 of a large oaken beam, which had, without doubt, been 

 there more than 150 years, and as it formed part of the 

 timbers of the edifice, had been secured from the rains. 



