What Tunings Did Bach Use?

People probably regard Bach as being the baroque composer, though in aspects like his preference for traditional polyphonic forms such as fugues and canons (he was a master at writing, even improvising the most complex of fugues) he must have been regarded a rather traditional composer at his time. On the other hand, he did expand into new, previously (almost) unexplored keys on the keyboard and thus may have helped advancing music towards the pre-classical era…