Answer:
I'm a ruler with 12 agents. Half of them work in the darkness. Who am I?
Cold head and feet; round as a ball; always turning around myself.
I have all the knowledge you have. But I am so small that I can fit into your hands. What am I?
I tremble at each breath of air, and yet can heaviest burdens bear. What am I?
I am tomorrow's yesterday and yesterday's tomorrow. What am I?
Runs over fields and woods all day. Under the bed at night sits not alone, With long tongue hanging out, Resting at your feet until we go for a walk