My goof on Francis death, 08 Nov 1936 is correct!! (my typo)
We both found the correct Madison Sewall Dow by different routes. Francis & Eugenia had a cottage at Goose Rocks Beach, then known as Beachwood, which is 3 miles from Cape Porpoise. Both Goose Rocks Beach and Cape Porpoise are part of the Town of Kennebunkport.Francis moved from PA in the early 1890s to Concord, where he was a professional photographer. Its likely that they happened to be at Goose Rocks in March (not beach weather by anyone's standards!) when Madison was born, but living in PA. Have not chased a formal birth record for Madison, but could easily see how PA got into the 1900 census as their home at that time.
Have no idea where the family lived in 1910 (have not looked).