In this issue

The accuracy of the daily 10.7-cm solar flux measurements taken at the National Research Council, Ottawa, has been investigated. The various system parameters are examined and an auxiliary experiment, using a horn antenna, is described. These studies lead to a revision of the early values of the solar flux and require the use of conversion factors to some of the published data. It has been estimated that the relative error between observations separated by intervals of months may be ??10 per cent during 1947 through 1949, and ??3 per cent during subsequent years. The systematic error in 1952-1953 was estimated at ??7 per cent.