Beds upon which Philadelphia stands, 363 



that devotion of time, opportunities, and action, to which I have 

 consecrated my life, not without hope that science may benefit 

 by my labours. 



As to geology, my dear F., you know as well as myself, that 

 I am not in the country for that. The instructions you gave me 

 are very valuable, and I shall be vigilant. The aspect of the 

 country will soon begin to change, and as I proceed, I will write 

 to you about all we see and do. Whatever I state to you, you 

 may rely upon ; and if you think my letters, such as they are, are 

 worthy of a place in your valuabie Journal, there you are at 

 liberty to place them, or any part of them. Do not be afraid of 

 my safety ; I take a reasonable care of my health and life. I 

 know how to guard against real difficulties, and I have no time 

 to attend to that worst of all kind of difficulties, imaginary ones. 

 Circumstances never within my control, threw me upon my own 

 resources, at a very early period of my life. I have grown up in 

 the school of adversity, and am not an unprofitable scholar there, 

 having learnt to be satisfied with providing for my family and 

 myself by my own exertions. The life I lead is my vocation, full 

 of smooth and rough paths, like every vocation that men variously 

 try. My physical constitution has always been good, and the fine 

 flow of spirits I have, has often greatly assisted me in some of 

 the most trying passages of my life. 1 know that I am engaged 

 in an arduous undertaking ; but if I live to complete it, I will 

 offer to my country a beautiful monument of the varied splen- 

 dour of American nature, and of my devotion to American orni- 

 thology. John James Audubon. 

 Ther. this day at 2, P. M. 78° Fahr. 



ON THE GEOLOGICAL CHARACTER OF THE BEDS UPON WHICH 

 THE CITY OF PHILADELPHIA STANDS. 

 By Peter A. Browne, Esa. 



Dr. Troost, in his geological survey of the environs of this city, 

 has stated, that it is placed on an alluvion. I am of an entirely 

 different opinion ; and the distinction between alluvial and di- 

 luvial, is important, and has been well pointed out by Conybeare, 

 and other geologists. These two deposites should never be con- 

 founded. The superficial soil upon which the city is built, con- 

 sists of boulders, gravel, sand, loam, clay, and iron. All these 



