Apparently a private
collection in Cherbourg, to which
Cohen had access, we may assume, either by personal inspection or by correspondence, Asselin sending
Cohen a list of the coins in
his collection that were missing in Cohen's first edition. I am not aware of an Asselin Sale, but maybe it would be possible to find out what happened to Asselin's
collection after
his death, which seems to have occurred between 1868 and 1880. In
vol. 7 of Cohen's first edition (1868), he always calls Asselin either just "Asselin" or "M. Asselin", e.g. p. XVII and p. 393, no. 15; whereas in the first volume of
his second ed. (1880), Asselin has become "Feu M. Asselin","the late Monsieur Asselin", e.g. p. 86, no. 157.
According to
Mattingly,
BMC V, p. cclviii, and
Carson,
BMC VI, p. 111, Asselin was a "
Collection,
Paris". Presumably they deduced that location from the fact that
Cohen cites Asselin, and
Cohen lived in
Paris. But
Cohen himself says Asselin lived in Cherbourg, in
his list of museums and collectors in the Supplement (
vol. 7) of
his first edition, published in 1868, to which you refer, p. XVII.