THE Nobel Prize for physics for 1936 is divided equally between Prof. Victor F. Hess of Innsbruck for his work on cosmic radiation and Dr. C. D. Anderson of Pasadena for his discovery of the positron. It was Prof. Hess's experiments in manned balloons in 1912 which first definitely proved the existence of penetrating rays which enter the earth's atmosphere from outside. This conclusion followed from the discovery that the ionization in a closed ionization chamber at a height of 4,000 metres was greater than at sea-level, and above this increased rapidly. Hess also showed that the ionization due to this new radiation decreased neither during the night nor during an eclipse of the sun, thus showing that the rays cannot come directly from the sun, so long, at any rate, as the rays travel in straight or nearly straight paths. It was this pioneering work of Hess which led to the view that the penetrating rays were really cosmic in origin. In more recent years, Prof. Hess, besides contributing much to the subject of atmospheric electricity, has paid especial attention to the study of the variation of the intensity of the cosmic rays with time. This work demands very accurate measurements over a period of years, since the variations are complicated and small in magnitude. From these and other similar investigations, a small daily variation has been established with certainty, and probably also a quite small variation with sidereal time of the order of 0.1 per cent. The existence of such an effect was predicted by Compton as a consequence of the assumption that the rays had their origin outside the Galactic System, and about the expected variation was found from the measurements of Hess and Steinmaurer. Prof. Hess's work on cosmic rays has extended over a period of more than twenty-five years, and it is with very great pleasure that all workers in this field now see this work receiving its due recognition.