xlviii Trans. Acad. Sci. of St. Louis. 



reference to the calibration of tuning forks, illustrating his 

 remarks by the use of the apparatus employed. 



Professor E. A. Engler discussed the locus of the inter- 

 section of a line through the focus making a constant angle 

 with the tangent to a parabola. 



Dr. William H. Warren, of St. Louis, was elected to active 

 membership. 



Nine persons were proposed for active membership. 



January 22, 1900. 



President Engler in the chair, fifty-four persons present. 



The resignations of Messrs. F. F. Gottschalk, G. C. Kins- 

 man and A. T. Terry were reported by the Council, which 

 further reported that Dr. O. Widmann, for some years treated 

 as a corresponding member, had at his request been added to 

 the list of non-resident active members, and that at the 

 request of a committee of the Engineers' Club of St. Louis 

 the President had appointed a committee of three* for con- 

 ference with said committee and other committees which 

 might be appointed by representative bodies to consider the 

 action necessary to secure the filtration of the water supply 

 of St. Louis. 



A paper by Mr. Charles Robertson, entitled Some Illinois 

 bees, was presented and read by title, and referred to the 

 Council with a view to its publication. 



Mr. William D. Denton addressed the Academy on But- 

 terflies and their mimicry, illustrating his remarks by a 

 series of beautifully prepared and mounted specimens. 



Mr. Gustav Cramer, Dr. E. H. Gregory, Mr. R. J. Hyatt, 

 Dr. Charles F. V. Ludwig, Dr. E. W. Oelfcken, Mr. Herbert 

 F. Roberts and Mr. James Lyall Stuart, of St. Louis, and 

 Professors T. H. Macbride, of Iowa City, Iowa, and Louis 

 Trenchard More, of Lincoln, Nebraska, were elected to active 

 membership. 



Seven persons were proposed for active membership. 



* The members of this committee were Mr. I. W. Morton, Dr. Amand 

 Ravold, and Dr. E. H. Keiser. 



