540 Account of the Country near the American Lakes, 



turn to rcftore the equilibrium, and an undulation will be vifible for feveral days after thofc 

 ftorms, and appears to be but flightly affefted by the alternate breezes already mentioned. 



In the wellern country, and efpecially in the neighbourhood of the lakes, dews are very 

 heavy. On the Ohio and Allegany rivers, and their numerous branches, fogs are very 

 common, and of remarkable denfity ; they do not however appear to contain any portion of 

 thofe noxious miafmata, which are fo frequently combined with the fogs on the eaftern 

 fide of the mountains ; nay the inhabitants of Pittfburgh confider them as poflefled of falu- 

 brious qualities. From a variety of obfervations I am convinced that the atmofphere in the 

 weftern country, and particularly in the vicinity of the lakes, contains a greater quantity 

 of moifture than in the middle Atlantic dates; The wooden works which contained my 

 inftruments were always uncommonly fwelled, and frequently very much injured in that 

 country, though conftantly defended from the rain, and occafionally expofed to the fun. 

 The ivory and wood of my feftors with brafs joints, always expanded above the metal ; 

 this expanfion was not fudden, but efFefled by flow degrees. Whether this excefs of 

 moifture arifes from the extenfive foreils which conftantly preferve the earth in a ftate of 

 humidity or from more permanent caufes, future obfervations muft determine. 



Iron is here more fufceptible of ruft, and brafs fooner tarniftied than in the Atlantic 

 Itates 5 but this fufceptibility of ruft I obferved to be greater in the forefts than in thofe 

 parts of the country that had been cleared for cultivation, and from thefe circumilances the 

 probable caufe is afcertained. 



The fouthern fliores of Lake Erie are generally high; in many places they are perpen- 

 dicular, and various ftrata of ftone are confiderably elevated above the furface of the water. 

 The ftreams which difcharge themfelves into the lake over thefe ftrata form a great variety 

 of cafcades of a romantic appearance, which increafe the beauty of the country, and muft 

 at fome future period enhance the value of the lands. 



At the lower end of the lake, and for fome diftance up it, thefe ftrata confift of lime- 

 ftone intermixed with flint and marine petrifaftions, but the other ftrata are generally flatc 

 and excellent freeftone. About Prefqu' Ifie there is but little lime-ftone to be feen, it lic» 

 in detached pieces, and is likewife interfperfed with flint and marine petrifaflions. 



In a large extent of country on the weftern fide of the Allegany Mountain, the ftrata 

 of ftone are horizontally difpofed, except in fome places where that pofition has been 

 changed by the undermining of creeks and rivers. In thefe places where the ftrata have 

 been deprived of their fupport, they have fallen from their original pofitions, and therefore 

 deviate from the general rule. This law of nature is eftabliflied on the fouth fide of Lake 

 Erie, but how far weft of the mountains the fame obtains, has never yet been afcertained. 

 The horizontal pofition of the ftrata on that lake has a pleafing efFed ; the fofter lamina are 

 worn away by the beating of the waves, the harder remain projected, and at a diftance 

 refemble wainfcotting or mouldings. 



From the horizontal difpofition of thefe ftrata the following conclufions may be deduced j 

 firft, that the country has eever been difturbed by thofe terrible convulfions which a great 



part 



