Watch List notes:

MEDALS BY SUBJECT, Science, Norway, Christopher Hansteen (1784-1873), Copper Medal, 1861, by R Bergslein, bust right, rev legend within and around wreath, 38mm (Wurzb 3566). Very fine though the reverse stained.
Hansteen, Norwegian geophysicist, astronomer and physicist, first to map the Earth's magnetic field.

Estimate: £30-50