A range curve of the external beam of the University of Chicago synchrocyclotron was taken inG5 stripped nuclear emulsion. The range of this beam in copper was also measured in order to determine its energy. Having a mean range of 41.1±0.1 g/cm2of copper, the beam had an energy of 208±4 Mev according to Aron's tables. The mean range of the same beam inG5 nuclear emulsion at 47 percent relative humidity was 41.3±0.2 g/cm2which is about 1.2 percent longer than that from Heinz's measurements and about 1.3 percent shorter than that calculated by Vigneron. At 47 percent relative humidity the average density of the emulsion was measured to be 3.85±0.01 g/cm3, in good agreement with the calculations of Wilkins.