The first three photos measure 4.25 inches wide by 6.5 inches high, and the last two are smaller at 2.5 inches wide by 4 inches high. The first two men seem to be wearing the same suit, so they could be brothers.
As far as I can tell from newspaper articles and census records, James Wesley Rothwell was the first photographer in Washington, Pa. and worked there from 1870 until at least 1900. However, it's unknown if another photographer kept the studio name after Rothwell's death in 1904.
If you are one of my husband's cousins and can help identify these Cowden photographs, I would love to hear from you!