sentences:  Henry Cavendish (1798) was the first to attempt to measure the gravitational attraction between two bodies directly in the laboratory.Earth's mass could be then found by combining two equations; Newton's second law, and Newton's law of universal gravitation.In modern notation, the mass of the Earth is derived from the gravitational constant and the mean Earth radius by
  Where gravity of Earth, "little g", is
  
  Cavendish found a mean density of , about 1% below the modern value.