Gentry Bros. Steam Calliope #3

My father wrote on the back of this picture "John Robinson Circus, air calliope. Old Gentry steam calliope". The boiler, whistles and keyboard have been removed and replaced with by this much smaller air calliope and operated by a generator which probably made more noise than the instrument. This is confusing to me since I always thought that this wagon came with Floyd King's purchase of the Gentry-Patterson Circus in 1926. Perhaps a Wagon Historian can straighten this out.