TYNDALL’S INSTRUMENT FOR MEASURING ABSORPTION OF INFRARED LIGHT BY TRACE GASES
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FIGURE 14.6 In 1861 John Tyndall published the results of his studies demonstrating that a number of trace atmospheric gases absorb infrared light, thereby identifying the mechanism for the warming of Earth’s atmosphere proposed a quarter-century earlier. In his tests, Tyndall would fill a tube in the instrument with a particular atmospheric gas, such as carbon dioxide. Then, by passing infrared light through the tube and measuring the amount absorbed, he could determine the potential contribution of that gas to the greenhouse effect. (From Tyndall, 1861)
(From Contributions to Molecular Physics in the Domain of Radiant Heat by John Tyndall, LL.D.F.R.S. D. Appleton and Company, 1873)