Signature of Dr. R. Shelton MacKenzie on the cover of “Songs for Music.” by Charles Mackay.  In the February 10th, 1838 issue of “The Durham Advertiser” there appeared a letter signed “Charles Dickens.”  The letter indignantly refutes a statement in the previous issue of the paper made by MacKenzie.  MacKenzie wrote a life of Dickens in 1870.