From Italy, Burr continued to Paris, where he matriculated at the Sorbonne and the Ėcole Pratique des Hautes Ėtudes. In Paris, he met the founder of comparative religious studies, Ernest Renan (1823-92), the author of important works on early Christianity, also known for his theories on nationalism and national identity. Burr focused his attention on the historical method and on developing technical skills at the Ėcole des Chartes, where, as he noted with surprise, it was possible to attend lectures for free. One of his favorite professors there was Arthur Giry (1848-99), an expert on medieval town charters who revived the study of diplomatics, i.e., the study of documents and manuscripts based on script, style, seals, signatures, and testimonia. Burr also enjoyed the lectures of Robert de Lasteyrie (1849-1921) on Merovingian archaeology.

On March 19, 1886, White wrote to Burr –who was still in Europe – asking for his opinion of the President’s plan to increase the coverage of medieval history in the Cornell curriculum:

“I have been greatly impressed, during this year, with the unsatisfactory condition of our course in history and political science. With the exception of the instruction given by Prof. [Moses] Tyler in American History, it seems to me exceedingly fragmentary and consequently unsystematic. Mr. Holder has taught the freshmen in Greek and Roman history, and in the history of England, giving them a good, rigorous course of text-book instruction […] It seems to me, a year should be given to the Middle Ages, for either two or three times a week [emphasis added–LF]. This course might alternate with a course of modern history, beginning with the time of the Reformation and reaching, say, to the French Revolution. […] Every student would have the opportunity of getting them both. […] I should be glad to have you write me without any delay as to how the whole scheme looks to you.”

[Frank Heywood Holder (1860-1935) served as instructor in ancient history and economics at Cornell between 1885 and 1889. He later spent two years at the universities of Freiburg and Göttingen. In 1891 he moved to Lawrence, Kansas, where he taught American history. In 1908 he became Chair of the Department of History at the University of Kansas.]

Burr returned to the United States in 1888 and resumed his duties at Cornell, where he was appointed Assistant Professor in 1890 and Professor in 1892. In addition to his academic duties, Burr was in charge of the transfer of President White’s magnificent collection of books and manuscripts to the Cornell University Library, a task completed in October 1891. In April 1892 he received – and declined – an offer from Stanford University, despite the blandishments of Stanford’s President David Starr Jordan, who wrote to him:

“You certainly do not know what a beautiful country [California] is, or what it is to be perfectly happy in the enjoyment of life and air until you get here, and certainly this fact taken with the fact that there are more musty old tomes and worthless incunabula (which, by the way, is the only cradle that you are ever likely to come in contact with if you go in your present reckless course) than you will find in all the collections on the east side of the Rocky Mountains.” (Burr Papers 14-17-22, box 2, folder 10.

In 1907, Burr married a Cornell student, Mattie Alexander Martin (B.A. 1902, M.A. 1906), who died during childbirth in 1909.

In the fall of 1892 Burr became the first Professor of Ancient and Medieval History at Cornell and in 1919 he was appointed John Stambaugh Professor of History. In addition to teaching and research, Burr supervised the acquisition of rare books and manuscripts for the Cornell Library – except for the Dante and Petrarch Collections assembled by Daniel Willard Fiske (1831-1904), which were the responsibility of Miss Mary Fowler.