His name may be Peter T. Cox, although difficult to read in 1910 Census.

1910 Census, Chester Twp., Clinton Co., OH, Apr. 18-19, 1910, p. 891787
Cox, Peter T.,?, head, 55, 2nd marriage, married 11 years, b. IN, parents b. IN
Martha E., wife, 46, 1st marriage, married 11 years, b. IN, parents b. PA
David K., son, 10, b. IN, parents b. IN
Mary, dau., 8, b. IN, parents b. IN
Joseph, son, 4, b. OH, parents b. IN
Miller, Mary, mother-in-law, 87, b. PA, parents b. PA

Mary Miller matches age of Mary Miller, mother of Martha E. Miller.