224 REPORT OF NATIONAL MUSEUM, 1904. 



sufficient number of facts, but that it is probable maybe judged by what follows. 

 (See Mitchill's views on p. 231.) 



In the same journal Samuel Brown, of Lexington, Kentucky, gave a 

 description of a cave on Crooked Creek, with remarks and observa- 

 tions on niter and gunpowder; Robert Gilmore, a descriptive cata- 

 logue of minerals occurring in the vicinity of Baltimore; while S. L. 

 Mitchill proposed an amendment to Maclure's chart of the United 

 States so far as it related to the character of the north side of Long 

 Island, which he showed to be alluvial and not primitive, as stated, 

 and Benjamin Silliman described the plain of New Haven as wholly 

 alluvial and of very recent origin. This paper is evidently a partial 

 reprint of one offered before the Connecticut Academy of Sciences 

 in 1810 and referred to elsewhere (p. 216). 



A paper by J. Corre de Serra, the Portuguese minister then resid- 

 ing in Philadelphia, read before the American Philosophical Society 

 in 1815, and published in their Transactions in 1818, is of interest as 

 showing the condition of knowledge relative to so commonplace a 

 phenomenon as that of rock weathering and formation of soils. His 

 paper was entitled Observations and Conjectures on the Formation 

 and Nature of the Soil in Kentucky. He regarded this soil as the 

 product "of the decomposition of an immense deposit of vegetables 

 which the ocean had left uncovered by any other deposition." 



It may be remembered that Jefferson, in his notes on the State of 



Virginia, had described in considerable detail and very eloquently the 



now well-known Natural Bridge of Rockbridge County, which he 



regarded as spanning a gigantic fissure, the result of 



F. W. Gilmer's to r . ° 



ideas on the some great convulsion. In the Transactions of the 



Natural Bridge. . »-»,., , . ■. ,i • <■ -i - -« •. /-i ->< ,\ -n 



American Philosophical Society tor 1Mb (1818) 1 rancis 

 William Gilmer had a paper on the same subject, illustrated by a full- 

 page plate. The bridge was described in detail and its formation 

 ascribed, not to a sudden convulsion, as argued by Jefferson, or to 

 any extraordinarily sudden deviation from the ordinary laws of nature, 

 but to the "very slow operation of causes which have always and 

 must ever continue to act in the same manner. 1 " This cause he rightly 

 considered to be the solvent action of meteoric waters on limestone. 

 In this respect Gilmer, although scarcely known to geological science, 

 was vastly in advance of the workers of his day. 



Three years later the Rev. Elias Cornelius, a man of education and 

 culture, but whose professional training seems to have quite unfitted 

 him for the work of a geologist, also discussed the subject in a paper 



in the American Journal of Science, giving the results 



Views of the . . . , . „ TT . . . 



Rev. e. Cornelius, of his observations on the geologv ot parts of Virginia, 



1819. 



Tennessee, and the Alabama and Mississippi territo- 

 ries. He dissented from any of the vie'ws thus far expressed, and in 

 the sublimity of his faith could see no good reason, or in his own 



