429' 



The death of Dr. Geo. W. IsTorris, at Philadelphia, March 

 4, 1875, aged 67 years, was announced by Mr. J. S. Price. 



Mr. Cope read a paper by the title, " A Synopsis of the 

 Vertebrata of the Miocene of Cumberland County, New 

 Jersey." (See page 361.) 



Dr. Cresson exhibited a map or diagram arranged on a 

 vertical scale to represent the five coal beds mined at EUen- 

 gowan, near Mahanoy City, representing the thickness and 

 subdivisions of each bed ; and on a horizontal scale to ex- 

 hibit the proportions of the various chemical elements ob- 

 tained by analysis. Of the mammoth bed, the uppermost 

 group of four benches is, at EUengowan, separated from the 

 middle group of three benches by 150 yards of rock, and the 

 middle from the lower group of four benches by an equal 

 distance, all three groups lying together, without the inter- 

 vention of rock measures, in the neio-hborino; collieries on 

 each side ; the total thickness of coal remaining always 

 about the same. 



Dr. Cresson exhibited and explained an American modifi- 

 cation of Bunsen's apparatus for determining the specific 

 gravity of any gas, and the obstacles to accuracy of the inves- 

 tigation when the given gas was either much heavier or 

 much lighter than the common air into which it escaped. 



Prof. Chase, being referred to, said that he had been re- 

 quested by Dr. Cresson to experiment with the instrument 

 in order to discuss its eccentricities, and had used the city 

 gas, obtaining various curves of velocity of exit, when the 

 uppermost and lowermost, or the two, or three, or other 

 numbers of inches at the top or bottom of the tube were 

 paired against each other ; but without entirely satisfactory 

 results. 



He considered it probable that the causes of irregularity 

 fell under three heads, viz.: 1st, the difference of density of 

 the medium into which the fine jet of gas issued (through a 

 microscopic hole in platinum foil) ; 2d, the vertical spiral 

 forms into wliich the currents must be thrown ; and 3d, fric- 

 tion, varying with condensation inside the instrument, 



