The photocopy of the original Edward Knox(1885) birth certificate that is posted on several family trees shows his father Edward Knox age 33 (b. ~1852), b. NY Occupation Gas fitter.(Gas fitter is the same thing as fitter, steam fitter, and pipe fitter.)
Your Edw. b. July 1885 is living with his Aunt in Hartford CT in 1900.I proved the connection between the Aunt and the father Edw. Knox, Gas fitter, b. 1851/2. (and the rest of the Knox family.)
Since Edw. was Mary Shield's 5th child, she almost had to have been married by 1880, but I sure can't find them in that census.