"B & J stands for Buegeliesen and Jacobson. B&J was an instrument distributor based in New York City. They did not manufacture their own instruments. Instead, they sold instruments made by an assortment of different companies. Their instruments were sold under a number of brand names, including Serenader, Mele, and SS Stewart. The Serenader name was first used on Ukuleles in 1926. The trademark was registered in 1927 and renewed in 1947, so it was used for quite a long period of time. Your ukulele was made by the Harmony Company of Chicago in the 1930s. It is one of Harmony's better ukuleles, with all mahogany construction. It appears to be in very nice condition."
- from Ukulele Hall of Fame Site