b PEEFACE 



pupil, Miss M. M. Tevis, from Dr. H. Carrington Bolton, Professor T. H. 

 Norton of the University of Cincinnati, Professor H. P. Talbot of the 

 Institute of Technology, and many others who cannot be enumerated. 

 Dr. Bolton's invaluable Catalogue of Scientific Periodicals and the Eoyal 

 Society Catalogue have been freely used and of great help in the verifi- 

 cation of data. 



Jas. Lewis Howe. 



Washington and Lee University, Lexington, Va., 

 December, 1896. 



