His result was in close agreement with his estimate of the age of the earth.The solar estimate was based on the idea that the energy supply for the solar radioactive flux is gravitational contraction.
Of course there seem to me to be fairly reasonable explanations for this observation which may allow for more slowly forming granitic rocks.
For instance, polonium radiohalos are sometimes associated with polonium bands generated by the polonium being transported by hydrothermal fluids along fractures.
Based on these assumptions he at first suggested an age of the Earth of between 100 Ma and 500 Ma.
This estimate was actually reduced over his lifetime to between 20 Ma and 40 Ma and eventually to less than 10 Ma. Perry, in particular, a noted physicists and former assistant to Kelvin, showed that cooling calculations using different but equally likely assumptions and data resulted in ages for the Earth of as much as 29 Ga.
These two independent and agreeing dating methods for of the age of two primary members of the solar system formed a strong case for the correctness of his answer within the scientific community.
This just goes to show that just because independent estimates of age seem to agree with each other doesn't mean that they're correct - despite the fact that this particular argument is the very same one used to support the validity of radiometric dating today.Of course, the detected variation is no more than 0.2% of the published rates, but this paper is still quite interesting since such a correlation was never suspected before.If magnetic fluxuations or other influencing forces are strong enough, radiometric decay rates could be much more significantly effected.Potassium - Argon and Argon - Argon dating are based on the current understanding that radioactive Potassium-40 decays to the stable form, Argon-40 with a half-life of approximately 1.25 billion years.There are some circumstances that can affect this rate such as magnetic fluctuations etc...Other factors and basic assumptions must also be considered.