Lesley.] 5o [ Feb 2 i, 



sylvania Anthracites," xiv, 706 ; "The Geological Distribution of Natural 

 Gas in the United States," xv, 565 ; "The Geological Relations of the 

 Nanticoke Disaster," xv, 629; "Coal Production in Utah,'' xvi, 356; 

 " Petroleum and Natural Gas in New York State," xvi, 906 ; "The Devel- 

 opment and Statistics of the Alabama Coal Fields for 1887," xvii, 206 ; 

 "The Geology of Buffalo, as related to Natural Gas ; Explorations along 

 the Niagara River," xvii, 398 ; " Statistics of Coal Mining and of Miners' 

 Wages in the United States," xviii (in pr'ess); " Natural Gas Explorations 

 on the Ontario Peninsular" (in press). A "Biographical Notice of 

 Captain W. R. Jones, of Pittsburgh," is among his unpublished papers. 



But his lasting fame will depend more upon his " Reports of Progress 

 of the Geological Survey of Pennsylvania," and the sheets of the "An- 

 thracite Coal Fields," than upon the admirable generalizations in the 

 papers mentioned above, proofs as they are of the healthy maturity of his 

 native genius for a true and broad synthesis of facts. It was in recogni- 

 tion of the high value of his Reports that the University of Pennsyl- 

 vania conferred on him the degree of Doctor of Science. 



Were I called to enumerate his actual discoveries, I should begin with 

 that of the curious ninety-foot side-throw in the Black Log Mountain gap 

 at Orbisonia, dying out at each end of the fault. It is worthy of special 

 notice as the only cross-fault as yet detected in any of the many mountain 

 gaps of the State, and as throwing a clear light upon the curious system 

 of throws encountered by the Rock Hill Iron and Coal Company in driving 

 their gangways westward, showing that the whole district had been sub- 

 jected to a warp movement fracturing it in parallel lines at right angles to 

 the strike. 



Then I would cite the Three Springs fault in the same district of South- 

 ern Huntingdon county, exhibiting the same features, but with a maximum 

 side-throw at the present surface of 1200 feet. In " Report F " will be 

 found his beautiful geometrical construction of this fault in the under- 

 ground, determining its extent in depth. 



I would cite also his discovery of the unsuspected subcarboniferous 

 coal measures in the Pocono (Vespertine) formation, No. X, cut by the 

 East Broad Top railroad through Sideling hill in the same county. The 

 immediate appreciation of the great importance of this revelation, by so 

 young a field worker, was the best evidence of his scientific genius that 

 could be given ; and his section of these very curious coal beds at the 

 dawn of the Coal Age has been our guide through a most difficult chap- 

 ter of Appalachian geology. 



Of equal importance to the petroleum industry was his discovery of the 

 increase in thickness of the Pocono formation, overlying the Bradford 

 oil formation, southward into Elk and Cameron counties, for it fully ex- 

 plained the failures of oil-well sinkers to reach the oil horizon which they 

 sought by rule of thumb, supposing that the same number of feet would 

 avail them in all parts of that region. 



His determination that the Salamanca conglomerate of New York was 



