XII PREFACE. 
The subject index contains a list of symbols; while [x] usually denotes 
the greatest integer ^x, occasionally such square brackets are used to 
inclose an addition to a quotation. The symbol * before an author's 
name signifies that his paper was not available for report. The symbol f 
before a date signifies date of death. Initials are given only in the first of 
several immediately successive citations of an author. 
Although those volumes of Euler's Opera Omnia which contain his Com- 
mentationes Arithmeticae CoUectse have been printed, they are not yet 
available; a table showing the pages of the Opera and the corresponding 
pages in the present volume of this history will be given in the concluding 
volume. 
The author is under great obligations to the following experts in the 
theory of numbers for numerous improvements resulting from their reading 
the initial page proofs of this volume: R. D. Carmichael, L. Chanzy, A. 
Cunningham, E. B. Escott, A. Gerardin, A. J. Kempner, D. N. Lehmer, E. 
Maillet, L. S. Shively, and H. J. Woodall; also the benefit of D. E. Smith's 
accurate and extensive acquaintance with early books and writers was for- 
tunately secured ; and the author's special thanl<:s are due to Carmichael and 
Kempner, who read the final page proofs with the same critical attention 
as the initial page proofs and pointed out various errors and obscurities. 
To these eleven men who gave so generously of their time to perfect this 
volume, and especially to the last two, is due the gratitude of every devotee 
of number theory who may derive benefit or pleasure from this history. In 
return, such readers are requested to further increase the usefulness of this 
work by sending corrections, notices of omissions, and abstracts of papers 
marked not available for report, for insertion in the concluding volume. 
Finally, this laborious project would doubtless have been abandoned soon 
after its inception seven years ago had not President Woodward approved 
it so spontaneously, urged its completion with the greatest thoroughness, 
and given continued encouragement. 
L. E. Dickson. 
November, 1918. 
