In this second volume, we translate another group of works among those published
by Gabrio Piola. Our aim is approaching: Probably, we are at one half of the task
which we assigned to ourselves. We believe that two more volumes will be enough
to give to the scholars who cannot read Italian but can read English, the possibility
to access to the complete works by Gabrio Piola. After the translation of the works
included in this volume, our convincement is even stronger than before. Piola seems
to us a giant in mechanical sciences and, tout court, in mathematical physics. Indeed
the very first Memoir published by Piola in 1825 is already full of original results,
deep mathematical concepts, and useful mechanical considerations. We have found
in this Memoir a formulation of Hamilton principle which surely dates some years
before the papers by Hamilton himself. We have found exciting epistemological
considerations in his first published work, and we can conclude that his scientific
personality was already completely developed at the age of 29 years. In our
opinion, the whole history of Continuum Mechanics and some parts of Analytical
Mechanics must be rewritten now. We hope that after the reading of our commentaries but especially the word by word translation of Piola’s Memoirs, the
reader will agree with us.