On the Liriodendron Tulipifera. 85 



vided they rest upon respectable authorities. " The 

 fear of having credulity imputed should never hinder 

 the publication of physical facts — however unaccoun- 

 table they may appear ; for, no one will pretend that 

 we already are acquainted with all the laws of nature : 

 on the contrary, they ought to be made generally 

 known, that their truth or falsehood may be estab- 

 lished by numerous experiments, especially when, 

 as in the present instance, the means' are so much 

 within the reach of" so many, " who may wish to 

 dertermine the matter for" themselves. 



In this place, it may not be amiss to mention 

 (though the fact has but little connection with the 

 preceding ones), that the wood of the Liriodendron, 

 especially the variety with yellow wood, owing to its 

 great sensibility with respect to the changes of the 

 atmosphere, is found to make an excellent hygro- 

 meter. This wood is observed to shrink and swell 

 very considerably, by reason of the alterations in the 

 degrees of dryness and moisture in the air. For the 

 hygrometer, a narrow, thin, and broad piece of the 

 wood, cut across the grain, is used. Mr. William 

 Dunbar (to whom, I think, we owe the knowledge 

 of the fact) found, that the sensibility of the wood 

 was improved by boiling it, after it had been made 

 very dry, in a solution of mild alkali, or common 

 potash. 



