George's Cause of Dry Rot, 197 



ployed as a preventive, viz. the passing and repassing of currents of heat 

 through the body of the timber. 



He took up this idea from an instance observed on his own premises, 

 namely, the destruction of an inner door in his wine-cellar. This was a new 

 deal door in an oak frame, which he had put up in 1821. It was well 

 painted on both sides, and completed in the best manner. In 1825 or 1826 

 this new door was found so decayed, that the pressure of a thumb indented 

 it, the interior having entirely lost its hardness and consistency, nothing 

 but the coats of paint keeping it in form. This accident attracted his par- 

 ticular attention, and induced liim to commence a course of observations to 

 ascertain the temperature of the air, both within and without the inner 

 vault. The result was, his finding, as in all similar cases, that there was al- 

 most constantly going on, an interchange of temperature from the interior 

 to the exterior, or vice versa, of the vault, and chiefly through the sub- 

 stance of the door. 



. As there is a never-ceasing ascent of vapour raised by heat from the earth, 

 and especially from any subterranean cavity such as the vault described, he 

 found that the heat only passed through the door, leaving the globules of 

 water condensed on the inside, when the heat was escaping outwards, and on 

 the outside, when the summer heat was pressing inwards to maintain an equi- 

 librium of the general temperature. No moisture, however rarefied, could 

 possibly pass through with the heat, the double coat of paint preventing. 

 The heat, therefore, was the only agent to which the author could attribute 

 the decomposition of the door, and it immediately occurred to him, that 

 if timber can be protected from becoming a conductor of heat, or placed 

 in equal temperature on both, or all sides, it will be free from any danger of 

 dry rot. 



On this hypothesis or fact Mr. George has founded his plan of pre- 

 vention, and has invented a curious and effective apparatus for ventilating 

 ships and cargoes liable to damage from heat, and for which he has ob- 

 tained a patent. 



The inductions which led to the conclusion are detailed with the utmost 

 minuteness by the author. The spontaneous transmission of heat from 

 place to place, and from one body to another, is accurately and naturally 

 given ; and though he conscientiously believes that the alternating transit 

 of heat is the decomposing cause, he does not venture to explain how it acts 

 to produce the effect. He offers a conjecture, however, which is to the fol- 

 lowing purport : " Heat is capable of entering into combination with other 

 things, and of making with them new and distinct substances, each sui 

 generis, and which substances may be either in a gaseous, or a liquid, or a 

 concrete and solid form. I think the process of vegetation, in the growing 

 of timber trees causes a quantity of heat to enter into chemical combination, 

 and in a concrete form, with other substances, and wilh them compose tim- 

 ber. So that, I think, heat in a concrete form, and in that form, as a part 

 of a visible material substance, visible to the eye, and having weight, like 

 other substances, is one of the component parts of timber, and as well of 

 other combustible substances." This combination, however, may be dis- 

 rupted; and " my notion, then, as to how the current or stream of heat, in 

 passing through timber, decays it, is, that when its motion is sufficiently 

 quick, it, by degrees, disengages its sister heat in the timber from its chemi- 

 cal combination in a concrete form with other substances, and makes it as- 

 sume its original form or shape of active heat, whereupon they both pass 

 out together, leaving the timber deprived of one of its component parts, 

 which consequently becomes decomposed and rotten." (pp. 44,4 5.) " Should, 

 however," he adds, "my notion on this matter be proved completely erro- 

 neous, it will be of no consequence, my undertaking having been not to 

 show how heat, by working its way through timber, decays it, but only the 

 fact that it does so." 



O .3 



