Mark Kapner

Mark Kapner is using an SG for this performance

In this video, Kapner can be seen playing a Farfisa Compact Duo at Woodstock.

In this video, Kapner can be seen playing a Hohner Pianet with Country Joe & the Fish. In addition to a Farfisa Compact Duo, Kapner also played a Hohner Pianet with the group at Woodstock.

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.