Unpublished letter, regarding paper on imperfect vision from Whitlock Nicholl to Sir Joseph Banks In this covering letter for Nicholl's paper found at AP/9/19/2, he introduces his paper and acknowledges that he chose to submit it because Banks had previously responded favourably to another paper on colour blindness communicated by [Benjamin Collins] Brodie but not published. Subject: Physiology Written by Nicholl in Ludlow [Shropshire, England]. 5 February 1820