CORRECTED (sorry, I forgot we are in the 21st century).
I know that Ampere speculated that all magnetic fields are due
to currents. But the prevailing explanation of magnetic fields,
at that time, was in terms of so-called magnetic charges. (In
that model B was defined as F acting on the N pole, per unit
pole.) Many textbooks published in 20th century still presented
magnetostatic in the same way in which they presented
electrostatics. The only difference was the recognition that
a magnetic dipole could not be cut into two monopoles. Did
Gauss believe in the reality of N (plus) and S (minus)
magnetic charges? When did the new definition of B (via
F=q*v x B) start to appear in textbooks?
Ludwik Kowalski