  Poincar\'e's approach to the three body problem has often been celebrated as
a starting point of chaos theory in relation to the investigation of dynamical
systems. Yet, Poincar\'e's strategy can also be analyzed as molded on - or
casted in - some specific algebraic practices for manipulating systems of
linear equations. These practices shed new light on both the novelty and the
collective dimensions of Poincar\'e's M\'ethodes nouvelles. As the structure of
a cast-iron building may be less noticeable than its creative fa\c{c}ade, the
algebraic cast of Poincar\'e's strategy is broken out of the mold in generating
the novel methods of celestial mechanics. But as the various components that
are mixed in some casting process can still be detected in the resulting alloy,
the algebraic cast of the M\'ethodes nouvelles points to some collective
dimensions of Poincar\'e's methods. An edited version of the present preprint
is to be published in the journal \textit{L'astronomie} under the title
"L'approche de Poincar\`E sur le probl\"Eme des trois corps". This publication
is an abstract in French language of a forthcoming paper - "The algebraic cast
of Poincar\`E's \textit{M\`Ethodes nouvelles}" - which will develop its main
claims as well as the historiographical and mathematical issues raised in
section 4 and section 5.
