CCXXIV 



while in this country, where we do things in a hurry, the proximate analy- 

 sis is used. Prof. Potter remarked that both were important. He had 

 therefore made an ultimate analysis of the Peruvian lignite with the fol- 

 lowing results : 



Moisture ii-iS 



Fixed Carbon 70.55 



Carbon in volatile matter 4 .05 



Hydrogen " " 1.884 



Oxygen 5 . 169 



Hydrogen with Oxygen 0.646 



Nitrogen 0.396 



Sulphur 0.205 



Ash 5 . 95 



Combined Water 5*8i5 



From the known heating power of the various combustible materials 

 here shown, the calorific power of this lignite was determined to be 80.4 

 per cent, of that of pure carbon. Prof. Potter finds the mean calorific 

 power of Colorado lignites to be 79 per cent, of that of pure carbon. Prof. 

 Potter will prepare a more complete paper for publication in the Transac- 

 tions. 



Mr. Riley exhibited a flint spear-head and hoe, found in this 

 county, the property of Mr. D. C. Lee, and also a water-urn, with 

 rounded bottom, which had been washed from the bank of the 

 Arkansas River, and was found floating down the stream. The 

 decoration of this urn was exceedingly interesting, consisting, of 

 the conventional wave-scroll so often seen in Greek ornament. 

 The figure was large, and was laid on in two colors, white, and 

 a red somewhat darker tlian the color of the material used in 

 construction of the vessel. 



Edwin A. Leslie, Charles Knower, John W. Sutherland, and 

 Frederick F. Hilder, were elected to associate membership. , 



November 6, 1876. 



Vice-President Albert Todd in the chair. 

 Twenty-two members present. 



EXPERIMENTS IN BINOCULAR VISION. 



Mr. Nipher made some remarks and described the following 

 experiments in Binocular Vision, the essential features of which 

 were published in Nature^ Aug. 10 : 



I. Fold a sheet of writing-paper into a tube about an inch in diameter. 

 Look through the tube at some distant object with one eye, and look 

 towards the open hand with the other eye, the edge of the hand being 



