The spectrograph – the first ever built – looked at the spectrum of bursts of radiations from the Sun over a wide spectral range for frequencies from 40 to 70 megahertz. It produced some spectacular results, demonstrating the great complexity of burst and storm phenomena. At Penrith, 50 kilometres west of Sydney in the foothills of the Blue Mountains, a fairly primitive wooden aerial was pulled around with ropes, and every twenty minutes it was changed so that it pointed towards the Sun. The data were analysed after four months of observations. In the first paper, published in 1950, he wrote: "We have identified three distinct spectral types of burst and … we shall call them Type I, Type II and Type III."