  A susceptibility function ${\chi}(L)$ is introduced to quantify some aspects
of the intermittent stick-slip dynamics of a rough metallic cylinder of length
$L$ on a rough metallic incline submitted to small controlled perturbations and
maintained below the angle of repose. This problem is studied from the
experimental point of view and the observed power-law behavior of ${\chi}(L)$
is justified through the use of a general class of scaling hypotheses.
