The reason I ask is because I have heard say that tempo ordinario is something like 60 bpm. Is it much of a stretch to assume Bach and his contemporaries could have used pendulum clocks as metronomes (on occasion)?
From what I have read (various books and articles) would (should my memory be accurate) indicate that clocks or watches were used in some case. Other cases would us terms like "heartbeat" or "moderate walking" (probably used to define "moderato") or "quick counting" or "slow counting."
It's not so easy to know what the actual timing was. Human heartbeat seems to be the most common measure.