  We are interested in the "Journal de Math\'ematiques Pures et Appliqu\'ees"
(JMPA) over the period 1917-1937. From the end of 1921, two mathematicians
worked to its publication, Henri Villat as editor in chief and Robert Montessus
Ballore as associate editor. Through unpublished letters, we descrive the
operation of the JMPA.
