sweep-second hand

sweep-sec·ond hand

(swēp′sĕk′ənd)
n.
A long hand on a clock or watch that measures seconds by moving the space of a minute for each second. Also called sweep hand.
References in periodicals archive ?
So, OK, the folks at CDC could have provided a little more certainty by referring us to the sweep-second hand on the clock, not leaving us to wonder.