1861.] 281 



of Natural History, New York, dated Sept. 16; the trustees 

 of the New York State Librai^, dated Aug. 24 ; the Histori- 

 cal Society at Chicago, dated Aug. 30, 1861. 



A letter announcing the transmission of publications was 

 received from the Royal Academy of Madrid, dated July 15. 



A letter requesting correspondence and exchanges was re- 

 ceived from Mr. T. A. Cheney, librarian of the Georgie Li- 

 brary, at Leon, Cattaraugus County, New York, dated Sept. 

 10, 1861. 



Donations for the Library were received from Prof. Paolo 

 Volpicelli, of Rome ; from the Royal Observatory at Cadiz ; 

 from the Royal Asiatic, the Chemical, and the Royal Geo- 

 graphical Societies, in London ; from the Boston Society of 

 Natural History ; from the Entomological Society and Frank- 

 lin Institute, of Philadelphia ; from the editors of the Astro- 

 nomical Journal, American Journal, and Medical News and 

 Library ; from Mr. Lorin Blodget, Mr. George Ord, and Dr. 

 J. Aitkin Meigs, of Philadelphia. 



The committee on Prof. Tafel's paper reported progress, 

 through the chairman, Dr. Coates. 



Mr. Lesley described the structure of a primary limestone 

 bed on the Brandywine above Chad's ford, in illustration of 

 the tongue-structure of folded anticlinals. 



This exhibition of crystalline limestone is made at and above 

 water-level in a quarry, worked to the depth of between one and two 

 hundred feet, in from the oriizinal '•face of the cliff, and termi- 

 nated by vertical walls of thirty or forty feet in height. Li the floor 

 of the quarry, at water-level, are seen two rude walls of quartzite left 

 standing. These are apparently horses of quartz rock in the mass 

 of the limestone. In the walls of the quarry are seen similar lens- 

 shaped masses of quartz fringed in some cases with mica slate. A 

 grand semicylindrical mass of quartz forms part of the wall-heading; 

 and another plate of quartz rock overhangs the edge of limestone 

 seen on the right at the floor level. Judging by the general irregu- 

 larity of the exposure, taken in connection with the few outcrops of 

 serpentine and marble, in the midst of generally steep or vertically 

 dipping strata of primary slates and sandstones, in this region (south 

 of the Chester County Valley), one might carelessly pass by this ex- 

 posure as if it were merely, what it is apparently, some crushed layers 



