Need Research help know any good websites?

Question

Does anyone know how the people of the 17th and 18th century tried to compute the mass of the earth?

Answer 1

To know the mass of Earth you need to know the universal gravitational constant. To know that you need to be able to measure the actual gravitational force between two masses small enough to weigh on a regular scale. See the source for how this was measured by Cavendish in the 1700s.