``Weighing' the Earth: a Newtonian Test and the Origin of an Anachronism

The measure G, the universal gravitational constant, is attributed to Henry Cavendish. Nevertheless, the intention of the English physicist was to measure the density of the earth, which at that time was necessary in order to decide between different theories about the composition of this planet. G was measured much later. In this article I will try to explain how Cavendish accomplished the famous experiment and what his results were. Likewise, I will consider the problems that can arise in the scientific training of students from maintaining anachronisms such as this.