Cope.] 14* 3 [Oct. 15, 



ent in large quantity. Journ. Franklin Inst., xxv, 1840, pp. 158-162; 

 Sturgeon. Ann. Elec, v, 1840, pp. 203-208. 



By Dr. H. R. Linderman and Prof. Robert E. Rogers 



Report upon the Wastage of Silver Bullion in the Melter and Refiner's 

 Department of the Mint of the United States, July 25, 1872. 8vo, pp. 82. 

 Government Printing Office, Washington, 1872. 



Report of the Committee [Franklin Institute] on Dynamo-Electric 

 Machines. Journ. Franklin Institute, lxxv, 1875, p. 289-303. 



Report of the Committee [Franklin Institute] on the precautions to he 

 taken to obviate the dangers of Electric Lighting. Journ. Franklin Insti- 

 tute, Dec, 1881. lxxxxii, pp. 401-408. 



Note. — In the preparation of the above lists, the Catalogue of Scientific 

 Papers, 1800-1873, compiled and published by the Royal Society of London, has 

 been consulted and used. 



Report on the Coal Deposits near Zacualtipan, in the State of Hidalgo, 

 Mexico. By E. D. Cope. 



(Read before the American Philosophical Society, Oct. 16, 1885.) 



Having obtained in the City of Mexico favorable information as to the 

 coal of Zacualtipan, in the State of Hidalgo, I resolved to devote some 

 time to an investigation of that locality. 



On my arrival at Zacualtipan, I was informed by my friend, Dr. San- 

 tiago Bernad, a French physician, who practices in the town and its sur- 

 rounding region, that the coal beds extend throughout a distance of five 

 leagues north and south, and two and a half leagues east and west. They 

 are owned in large tracts called quadras by different persons. I examined 

 sixteen exposures within a distance of five miles of Zacualtipan, north- 

 east, south- east and south, with the following results : 



The geological structure of the country is as follows : The town of 

 Zacualtipan is situated on the border of the plateau of Mexico, where it 

 begins to break off to the lower level, which two days' journey on horse- 

 back eastward becomes the Tierra Caliente of the State of Vera Cruz. 

 The plateau is, therefore, much broken by ravines which open to the east- 

 ward. The high plateau just east of Zacualtipan is about 7000 feet above 

 sea-level. The eastern border of the plateau is supported and protected 

 by the lines of several trap-dykes, whose faces form precipitous walls 

 which bound the ravines, generally on one side. To the east and west of 

 the town the high lands consist of a silicious limestone, which looks a 

 good deal like that of subcarboniferous age in the United States, but, is 

 said by M. Barcena, of the National Museum of Mexico, to be of Cre- 



