Abstract
In this article Mr Kyle has drawn attention to an error which is supposed to occur in the measurements with the K. Ångström compensation pyrheliometer. The poor thermal conductivity of the blackening applied to the receiving strips of the pyrheliometer has the consequence that equalizing the temperature of the back surfaces does not strictly equalize the temperature of the front surfaces, the front temperature of the illuminated strip being slightly higher than that of the front surface of the strip heated from within by the electrical current. DOI: 10.1111/j.2153-3490.1968.tb00362.x