When one plate goes under another what is the force pulling it down?

Idon't know. the question you are trying to ask doesn't make sense.

Historians are researchers of the past or people who understand the history of people. with this field, they must possess qualities such as being unbiased, patient, efficient reader, has a knack for logic and critical thinking and reasoning, disciplined, open-minded, resourceful, with good analytical ability, good reasoning skills and problem solving!

The answer to the first one is barometer.