An estimate of the geological age of the Earth.

Dublin, The Royal Dublin Society, 1899. Large 4to (29.0 x 22.5 cm). 44 pp. Original printed wrappers. A well-written and well-reasoned treatise, dealing with one of the most important conundrums in 19th century geology, namely the age of Planet Earth. After careful calculations, based upon the original, hypothetical condition of the sea and the subsequent accumulation of minerals - in particular sodium - in seawater, the author concluded that Earth probably was between 80 and 90 million years old. This was a fair estimate, given the state of knowledge at the turn of the 20th century. The Irish physicist and professor of geology at the University of Dublin John Joly (1857-1933) ".was an famous for his development of radiotherapy in the treatment of cancer. He is also known for developing techniques to estimate accurately the age of a geological period, based on radioactive elements present in minerals, the uranium-thorium dating. . On 17 May 1899 Joly read his paper, An Estimate of the Geological Age of the Earth to the Royal Dublin Society. In it, he proposed to calculate the age of the earth from the accumulation of sodium in the waters of the oceans. He calculated the rate at which the oceans should have accumulated sodium from erosion processes, and determined that the oceans were about 80 to 100 million years old. The paper was quickly published, appearing 4 months later in the Society's Scientific Transactions. Although this method was later considered inaccurate and was consequently superseded, it radically modified the results of other methods in use at the time. . In 1903 he published an article in Nature in which he discussed the possibility of using radium to date the Earth and went on to study the radioactive content of the Earth's crust to formulate a theory of thermal cycles, and examined the radioactive constituents of certain rocks as a means of calculating their age. Working in collaboration with Sir Ernest Rutherford, he used radioactive decay in minerals to estimate, in 1913, that the beginning of the Devonian period could not be less than 400 million years ago, an estimate which is in line with modern calculations"(Wikipedia). The Smithsonian Institution in Washington, DC republished this work in octavo in their Annual Report. This, however, is the original edition. Uncut. Wrapper edges a bit toned, otherwise an excellent, clean copy. Rare.