  In April 1925, Enrico Fermi was only 23 years old and he had graduated less
than three years earlier. Despite his age, Fermi was invited at the University
of Rome by Federigo Enriques to give several lectures on the recent advances in
physics at the Italian Mathematics Seminar. Enriques was also the editor of
"Periodico di Matematiche", an important Italian journal concerned primarily
with secondary school math teachers. Some of the articles published by
"Periodico di Matematiche" correspond to the lectures which Fermi gave during
seminars and meetings of Italian mathematicians. Here we propose an English
translation for one of these articles, entitled "Sopra la teoria cinetica dei
corpi solidi" and discussing the kinetic theory of solids. We believe that this
Fermi's work offers a twofold interesting perspective: on one side, it allows
us to explore the problems related to the structure of matter of emerging at
the time as seen by the eyes of a bright, young physicist. On the other hand,
it shows us the undoubtedly high scientific level of the articles read in Italy
by the secondary school math teachers in the Twenties.
