The experiments also used lead and cork balls. For these experiments, egg-shaped fishing weights and a cork fishing float were used. Time measurement was a major issue in many of Galileo's experiments. For his pendulum experiments, Galileo seems to have compared the pendulums in pairs over the same time. This method was used for comparison in these experiments.
Pendulums nearly return to their release heights.
Galileo observed that the bobs of pendulums nearly return to their release height. Today this fact demonstrates conservation of energy, a principle not yet discovered in Galileo's time. As a recreation, pendulums were released from different heights. The height the pendulum returned to was noted and compared to the release height. No quantitative measurements were made, but in every trial, the pendulum's return height was very close to its release height.