4-21-21. Thomas Craig to H. Poincaré

May 7 1887

American Journal of Mathematics

Johns Hopkins University


My dear friend,

I have just read your memoir “Sur les résidus des intégrales doubles” in the Acta, and want to tell you how much pleasure it has afforded me.11endnote: 1 Poincaré (1887). I don’t remember having read anything in a long time that has interested me so much. I had read all I could find on the subject, but found it all, as you describe in the beginning of your memoir, unsatisfactory. Picard’s definition of a “period” bothered me a good deal; I saw that the integrals were not constants. That the “periods” did not depend on the assumed function but upon the choice of the auxilliary variables etc. I began to be afraid that I did not really know what a “period” was. Please send me a tirage à part if you have any. I have only written to express my pleasure in reading your memoir, as I have long wished to read something on the subject, and have expressed that wish to friends here a score of times. Hoping my dear friend to hear from you soon, I remain as ever,

Sincerely yours,

Thomas Craig

ALS 2p. Collection particulière, Paris 75017.

Time-stamp: "28.01.2021 13:47"



  • H. Poincaré (1887) Sur les résidus des intégrales doubles. Acta mathematica 9, pp. 321–380. link1 Cited by: endnote 1.