Lesley.] 4-j-i [March 5, 



Resume. The Bradford sand is fine but porous ; constant in thickness ; 

 homogeneous in section ; the character of the sections remaining the same 

 over a very wide area. 



The Venango sands are sometimes coarse, pebbly and porous, and sonic- 

 times fine, compact and clayey ; variable in thickness ; heterogeneous in 

 section and subject to sudden changes in very short distances. 



The difference in the structure of the sands, when considered in connec- 

 tion with their relative productiveness, is a strong argument in support of 

 the view which has been accepted by the best informed of our geologists 

 that the sands are only reservoirs or sponges which serve to hold the oil, 

 coming almost entirely from an inferior formation to which it is indigenous. 



The conditions under which these two sands were deposited must have 

 been essentially different. The Venango sands were undoubtedly shore 

 and shallow water deposits. The currents, by which the sediments form- 

 ing the group were transported, were evidently rapid and shifting. It has 

 been suggested that the sands may have been laid down in a river bed. 

 This would necessitate dry land at the time, on either side of the terri- 

 tory where the sands are at present found. 



The Bradford sand was possibly deposited in deeper water, by a slower 

 •and more constant current. It does not bear any evidences of being a 

 shore deposit, but was probably formed in a bay or estuary. 



An Obituary Notice of the Late John W. Harden. By J. P. Lesley. 



(Read before the American Philosophical Society, March 5, 1880.) 



John W. Harden was born at Leicester, England, June 19th, 1816, and 

 died at Philadelphia, November 8th, 1879. 



He was versed in the arts of Horticulture and Floriculture, and for a 

 Dumber of years followed them professional ly. Was especially successful 

 in designing, ornamenting and laying out estates, notably those of Hon. 

 Capt. Oust, Wormleybury, Hertfordshire and Sir Ralph Howard, Bart., 

 Craven Cottage on the Thames. 



He commenced practice as a Mining Engineer in 1846, and in that year 

 took the management of the Hawkesbury Colliery, near Coventry, Eng- 

 land. He was the means of introducing into the Warwickshire coal field 

 most of the modern improvements at that time only in use at the best col- 

 lieries in the North of England. Wire ropes took the place of hemp ropes 



