...d the performance was interrupted by himself at intervals, to look for an imaginary pianist and singer who never came, but who became as real to the audience as Jefferson's imaginary dog Schneider in Rip Van Winkle , for whom he was always vainly whistling. This unseen singer, we were told, would thrill every heart with his song, Is it Raining, mother Dear, in South Boston? or, Mother, you are one of my par...