256 Observations on Humboldt's Works 



an ancient union, we might suppose that the same had existed 

 between Europe and New Holland, for these countries, as has 

 been already remarked, have plants that are common to both. 



The hypothesis, advanced by the author, p. 54, viz. , that the 

 great spread of Adianthum Capillus VeneriSj may, perhaps, be 

 ascribed to the transport of filtering stones, will scarcely find 

 support. 



5. Comparative View of the Temperature of both 

 Great Continents, p. xxvi. — xxxiii. 



This part of the treatise presents a most valuable addition to 

 our knowledge of the relations of climate in different countries, 

 and corrects likewise some erroneous conclusions hitherto re- 

 ceived. The author particularly points out the unsoundness of 

 the opinion, that every part of North America is colder in the 

 same proportion than parts of Europe, placed under the same 

 latitude, and proves that the difference between the two parts 

 of the world is always greater towards the North Pole *. 



Although we must certainly agree with the author here in 

 the main question, yet the progression of the decrement of 

 heat in the two parts of the world, as laid down by him, does 

 not appear to be demonstrated ; in the first place, it is founded 

 upon too few observations ; and, secondly, the comparisons are 

 made in too arbitrary a manner. To render this more, clear I 

 will cite a few of these comparisons : — 



• The author here speaks of the difference between the New and Old 

 Continents ; but the points of comparison are taken from the western parts 

 of Europe and Africa. He also shews afterwards that the climate in the 

 eastern part of the Old Continent is colder than in the western. 



t No place in Egypt is mentioned in the table. 



