Introduction 
xm 
The regret is increased that his observations could not have been published shortly after they were concluded and 
during his lifetime. It is evident that they are of such a degree of accuracy that they might safely be made the basis 
of investigations of various problems of the sun’s rotation, aside from their value as records of the solar activity. 
The editor acknowledges his indebtedness to his wife for assistance in reading the proofs, and to Mr. Philip 
Fox for aid in various ways; also to Professor Samuel J. Saunders, of Hamilton College, for his thorough but 
unavailing searches for the missing papers of Dr. Peters. 
Yerkes Observatory 
The University of Chicago 
September, 1907 
