84 



we must admit, that an hypothesis, according to 

 which organic life seems gradually to augment 

 on the Globe, occupies more agreeably our ima- 

 gination, than the old system of the cooling of 

 our planet, and the accumulation of the polar 

 ice. Some parts of physics and geology are 

 merely conjectural ; and it might be said, that 

 science would lose much of it's attraction, if we 

 endeavoured to confine this conjectual part 

 within too narrow limits. 



HYGROMETRi AL STATE OF THE AIR. 



\( 



Notwithstanding the doubts which have been 

 raised in these latter times respecting the accu- 

 racy, with which hair or whalebone hygrometers 

 indicate the quantity of vapours mingled in the 

 atmospheric air, it must be admitted, that, even 

 in the present state of our knowledge, these in- 

 struments are highly interesting to a naturalist, 

 who can transport them from the temperate to 

 the torrid zone, from the northern to the south- 

 ern hemisphere, from the low regions of the air 

 that rest on the sea to the snowy tops of the 

 Cordilleras. I would rather, says Mr. de Saus- 

 sure*, that the most imperfect instrument were 

 made use of, a hempen string with a stone sus- 

 pended to it, than entirely neglect researches, 



* Essai sur PHygrometrie, § 353. 



