The division viol is an English type of bass viol, which was originally popular in the mid-17th century, but is currently experiencing a renaissance of its own due to the movement for historically informed performance.
The division viol also had a very large range with the tuning D–G–c–e–a–d', resulting in the ability of skilled players to play divisions on any part in a polyphonic vocal piece.
[1] The division viol may be historically connected with the viola bastarda, and came into being in the mid-17th century in England.
Christopher Simpson, a prominent viol player, wrote a treatise on how to play the division viol, aptly titled The Division-viol, or The Art of Playing ex tempore to a Ground (1665), and also The Division-Violist (1659).
Both of these are frequently used as references by those interested in historically informed performance on the viol.