Abstract
Measurements of global radiation Eg↓ made in the first half of the 20th century are reviewed. The thermoelectric pyranometers used to measure Eg↓ in the United States, Western Europe and Russia are described and the published sources of data available up to and including the 1957 International Geophysical Year are documented together with the few analyses of this data which have been reported. Two 100‐year‐long series measured at Potsdam, Germany and Washington, DC in the United States are presented to illustrate the potential value of the early measurements in understanding the changes in Eg↓ which have occurred in the last 60 years.

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