Who decided on the value of a second

Last night, my overwrought brain decided to fasten onto bizarre thoughts and worries about time keeping. "If only we could restablish the value of a second," I thought. "We'd be to fix all the problems we have with time keeping."

This morning, of course, all I could think of is "What problems did I think it would solve, exactly?"

It does lead to an interesting question in waking life, however -- who did establish the values that are now part of our everyday life, and why?

An unrelated photo: