Here are two pipes I recently purchased that have the Peterson "P" on the stems. I've tried to find any photos of when they possibly were made by Peterson and I would love some help from my buds on here. If you have any info, that would be WONDERFUL. I've dug up some history about Pre-Patent/Patent Era Peterson's, but I'm very reserved about claiming that these were made during that time. There are no patent markings or "Made in Ireland" type stamps on the stem, only the "P" that Peterson is so known for as you can see pretty clearly in the second photo.