That's true, but in this case it's used to describe a clock that's used to record and pay for an employees time. That being said, we could digress to talk about any kind of clock here.

Ever notice the anagram of HORUS = HOURS?

Speaking of being "on the clock" I have to get ready for work. In the meantime.. here's a 10,000 year clock.

"Let the dot of light beckon you.."

The 10,000 Year Clock

There is a Clock ringing deep inside a mountain. It is a huge Clock, hundreds of feet tall, designed to tick for 10,000 years. Every once in a while the bells of this buried Clock play a melody. Each time the chimes ring, it’s a melody the Clock has never played before. The Clock’s chimes have been programmed to not repeat themselves for 10,000 years. Most times the Clock rings when a visitor has wound it, but the Clock hoards energy from a different source and occasionally it will ring itself when no one is around to hear it. It’s anyone’s guess how many beautiful songs will never be heard over the Clock’s 10 millennial lifespan.

The Clock is real. It is now being built inside a mountain in western Texas. This Clock is the first of many millennial Clocks the designers hope will be built around the world and throughout time. There is a second site for another Clock already purchased at the top of a mountain in eastern Nevada, a site surrounded by a very large grove of 5,000-year-old bristlecone pines. Appropriately, bristlecone pines are among the longest-lived organisms on the planet. The designers of the Clock in Texas expect its chimes will keep ringing twice as long as the oldest 5 millennia-old bristlecone pine. Ten thousand years is about the age of civilization, so a 10K-year Clock would measure out a future of civilization equal to its past. That assumes we are in the middle of whatever journey we are on – an implicit statement of optimism.

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[link to longnow.org]