  The precise description of the motion of anisotropic particles in a flow
rests on the understanding of the force and torque acting on them. Here, we
study experimentally small, very elongated particles settling in a fluid at
small Reynolds number. In our experiments, we can, to a very good
approximation, relate the rate of rotation of cylindrical tungsten rods, of
aspect ratios \beta = 8 and \beta = 16, settling in pure glycerol to the torque
they are experiencing. This allows us to compare the measured torque with
expressions obtained either in the slender-rod limit, or in the case of
spheroids. Both theories predict a simple angle dependence for the torque,
which is found to capture very well the experimental results. Surprisingly, the
slender-rod approximation predicts much better the results for \beta = 8, than
for \beta = 16. In the latter case, the expression obtained for a spheroid
provides a better approximation. The translational dynamics is shown to be in
qualitative agreement with the slender-rod and spheroid models, the former one
being found to represent better the experimental data.
