Immediately after a symposium session on mesotron instability reached a consensus that more definitive observations were needed, Rossi and Compton began to plan an experiment. Because the intensity of the hard component increases with altitude, while the density of air decreases, Compton suggested that the investigations should be carried out on Mount Blue Sky in Colorado, where he had worked in the early 1930s, and where access to a research site at 4,310 metres (14,140 ft) elevation is provided by the Mount Blue Sky Scenic Byway, the highest paved road in North America. He urged Rossi to begin a series of experiments that summer, before snow blocked the road, and to help, enlisted two of his friends, Norman Hillberry and J. Barton Hoag, and a student, Winston Bostick. Rossi and his helpers hurriedly assembled equipment and loaded it onto a dilapidated bus that Compton borrowed from the zoology department.