In 1779 the Comte du Buffon tried to obtain a value for the age of Earth using an experiment: He created a small globe that resembled Earth in composition and then measured its rate of cooling. This led him to estimate that Earth was about 75,000 years old.
In 1862, the physicist William Thomson, 1st Baron Kelvin published calculations that fixed the age of Earth at between 20 million and 400 million years
Thomson gave his last estimate in 1897 : "that it was more than 20 and less than 40 million year old, and probably much nearer 20 than 40
Boltwood, by the end of 1905 had provided dates for 26 separate rock samples, ranging from 92 to 570 million years.
Refinements in the technique would later give ages for Boltwood's 26 samples of 410 million to 2.2 billion years.
Holmes published The Age of the Earth, an Introduction to Geological Ideas in 1927 in which he presented a range of 1.6 to 3.0 billion years.
An age of 4.55 ± 0.07 billion years, very close to today's accepted age, was determined by Clair Cameron Patterson using uranium-lead isotope dating (specifically lead-lead dating) on several meteorites including the Canyon Diablo meteorite and published in 1956