Masato Sakurai has just located for me a couple of sources for the tune called (in the Japanese Sanbika (???, 1954 ed.) "CROSBY" and attributed there to Ms. Van Alstyne. I've been trying to find this source for years. I am thrilled. And it does appear to be in all probability one of Fanny's relatively few original musical compositions. Not sure how or when I'll be able to incorporate this into the Hymnary, but it'll be one of my life goals now.