Judge Chase was defended by the ablest lawyers in the country, including Luther Martin, Robert Goodloe Harper (1765-1825), Philip Barton Key (1757-1815), Charles Lee (1758-1815), and Joseph Hopkinson (1770-1842).
Hopkinson pointed out that the greatest dissipation of energy which can be caused by a to-and-fro reversal is approximately represented by Coercive force X maximum induction fir.
As in Hopkinson's experiments, ring magnets were employed; these were wound with primary and secondary coils of insulated platinum wire, which would bear a much higher temperature than copper without oxidation or fusion.
According to Hopkinson's calculation, this sample behaved as if 91% of the iron contained in it had completely lost its magnetic property.'
Dr Hopkinson presented a rare combination of practical with theoretical ability, and his achievements in pure scientific research are not less intrinsically notable than the skill with which he applied their results to the solution of concrete engineering problems. His original work is contained in more than sixty papers, all written with a complete mastery both of style and of subject-matter.