  We study the selfsimilarity and the Gibbs properties of several measures
defined on the product space $\Omega\_r:=\{0,1,...,\break r-1\}^{\mathbb N}$.
This space can be identified with the interval $[0,1]$ by means of the
numeration in base $r$. The last section is devoted to the Bernoulli
convolution in base $\beta={1+\sqrt5\over2}$, called the Erd\H os measure, and
its analogue in base $-\beta=-{1+\sqrt5\over2}$, that we study by means of a
suitable system of numeration.
