Letter from Richard Mackenzie to Richard Butcher Manuscript letter from Richard Mackenzie to Richard Butcher asking him to send details of his recent case of excision of the knee joint as the operation will 'again be under discussion at the Medico-chirurgical society'. Mackenzie wishes to use Butcher's experience to support his own idea that the operation is 'both a justifiable and a good one'. 24 February 1854