The octobass is an experimental instrument created in 1850 by Jean Baptiste Vuillaume. It is a member of the viol family, 3 stringed, and really really big (3.5 meters high). so big that to play a note required one man to operate a series of foot pedals connected to capos on the fingerboard and another to bow the strings. it is tuned in 4ths (C, F, B) rather than fifths (C, G, D) as a cello. The reason being that you don't have to stretch your fingers quite as far when fingering notes. the concept of tuning in 4ths was originally developed for double basses, explaining why it carried over to the octobass even though it was fingered by capos anyway. it was said to have a fantastic sound, although it was never widely adopted due to its impracticality, weight, difficulty in playing, et cetera. one example is on display in the Musee de la Musique, taking its rightful place next to the hurdy gurdy, Chilean stick fighting guitar, and other bizarre impractical instruments.