A preliminary report on our first extensive measurements of the cosmic‐ray intensities at medium underground (5880 m water equivalent) is given. In these experiments, carried out during 1951 and 1952, two identical portions of photographic plates, one bare and one shielded with Cd, were exposed at identical temperature. For the controls, which were exposed at the surface of the earth, there was found a good agreement between our results and those obtained by Yagoda and Kaplan for slow neutrons. The Cd difference counts obtained at the underground station were much higher than the controls.