e.g. Max Harold Fisch, Christian J. W. Kloesel, "Essay on the Editorial Method", in Writings of Charles S. Peirce: 1879-1884, vol. 4 (1989), p. 629:
"In all MSS in this period, Peirce inscribed "st," "nd," "rd," and "th" in the superscript position: for convenience's sake, they are on the line in typewritten pieces. In published pieces the ordinals are superscripted to conform to Peirce's style; "2nd" and "3rd" are emended to "2nd" and "3rd". When Peirce typed abbreviated ordinals on the line, these mechanical exceptions attributable to his typewriter have been changed to superscript ordinals."
