Cavendish calculations of earth density

I have a decent concept of the mechanics of Cavendish's experiment and data, but I have not found how to go from the data listed in his chart of conclusions to the density figures.

I found this link to the data chart. It lists the motion of the weight and the arm and the time of vibration (not sure I get the significance of this). These figures apparently lead to the calculation of the density of the earth in terms of the density of water.

Any pointers in how that calculation is made from the experimental data is appreciated, even a suggested reference.