At the tenth General Assembly of U.R.S.I. held in The Hague, Netherlands, in August 1954, the author presented a set of curves showing spectra of five bright, non-thermal, discrete radio sources. The spectra were based on the recent measurements at centimetre wave-lengths made with the 50-ft. antenna at the Naval Research Laboratory and on earlier published values for the flux at longer wave-lengths. The spectra are shown in Fig. 1. It is seen that there is in each case a discontinuity in the region between 30 and 100 cm. wave-length. Unfortunately, there had been no measurements made in this middle region. The slope of the two ends of the curve is nearly the same. There was considerable doubt at the time as to whether the spectra were in fact S-shaped as they would be if the two ends were joined in the simplest fashion. One possibility was that, due to the different techniques used in the centimetre and metre regions both in antennas and receivers, there might exist a calibration error of sufficient magnitude to cause the offset. For many reasons, this was hard to believe. In particular, measurements of solar flux at long and short wave-lengths yield a consistent picture.