It would not only be trouble~some to the workman, but often bring on mistakes, were he to count the turns of the handle, which perhaps for hours together he is moving; a zone-clock, therefore, has been contrived to release him from that care... It strikes a bell..when the telescope is come to one of the limits of the zone.
W. Herschel in Philosophical Transactions (Royal Society) vol. 85 398
Originally published as part of the entry for zone, n.
zone, n. was first published in 1921; not fully revised.