  Galatius and Randal-Williams defined a topology on the set of closed
submanifolds of ${\mathbb R}^n$. B\"okstedt and Madsen proved that a
$C^1$-version of this topology is metrizable by showing that it is regular and
second countable. Using that the scanning map of a topological sheaf on
manifolds is an embedding, we give an explicit metric to the space considered
by B\"okstedt and Madsen. Then, we compare this topology with the Fell topology
and we use the Hausdorff distance to give another metric to the space of
Galatius and Randal-Williams.
