An RMI Band Organ can be seen on the cover of Jellyfish's album Spilt Milk (in background on far right). Manning is an avid collector of vintage keyboards, so he likely owned this rare calliope-style organ.

In this YouTube video, Kapner can be seen playing a RMI Band Organ. Kapner's solo begins at the 1:15 mark. A good view of the wheels and back of the organ can be seen at 2:48.

It is unknown if this is the same "calliope" that was used on the album version of the song, though it seems likely. The band's previous keyboardist David Cohen recalled,

“We spent three or four hours trying to arrange the song, trying to figure out how to make the song work for a rock band. We were frustrated. So we took a break, and I started to play a ragtime version of it on a piano, just fooling around. Sam Charters jumps up, and says, ‘That’s it!’ and everyone got all excited. So we decided to do it like a ragtime song. Then, one of the instruments that was sitting around the studio was this electric calliope, so Joe got the idea, ‘Let’s put that on it!’”

Cohen doesn’t recall the make of the small electric calliope, but says it was painted to look like a traditional circus model. It came from a local instrument rental company, and Charters says it had caught his eye in a catalog “because I knew about calliopes from early New Orleans jazz history.”

While this keyboard is purely electronic and therefore isn't a true calliope, its appearance and sound were purposefully crafted to best resemble that of a calliope, creating a potential source of confusion.

This is likely the "calliope" that was Cohen played on Country Joe & the Fish's "I-Feel-Like-I'm-Fixin'-to-Die Rag." Cohen recalled,

“We spent three or four hours trying to arrange the song, trying to figure out how to make the song work for a rock band. We were frustrated. So we took a break, and I started to play a ragtime version of it on a piano, just fooling around. Sam Charters jumps up, and says, ‘That’s it!’ and everyone got all excited. So we decided to do it like a ragtime song. Then, one of the instruments that was sitting around the studio was this electric calliope, so Joe got the idea, ‘Let’s put that on it!’”

Cohen doesn’t recall the make of the small electric calliope, but says it was painted to look like a traditional circus model. It came from a local instrument rental company, and Charters says it had caught his eye in a catalog “because I knew about calliopes from early New Orleans jazz history.”

The Band Organ fits both Cohen's carnivalesque description and the keyboard sound heard on the album. And while this keyboard is purely electronic and therefore isn't a true calliope, its physical appearance and sound were purposefully crafted to best resemble that of a calliope, creating a potential source of confusion. Additionally, Cohen's replacement in the band, Mark Kapner, later played this same RMI model on a television show, linking the instrument to the band.