Spectral and spatial distributions of neutrons and gamma rays were measured in a simple cavity-duct configuration to observe profiles of cavity streaming. The change of the profiles of neutrons and gamma rays is examined by blocking source neutrons with a 32-cm-thick aluminum plug. The following observations resulted from the experiments: Fast neutrons of several million electron volts energy streamed through ducts. The neutron and gamma-ray spectra were similar except in the source neutron beam. The gamma rays were predominantly those arising from neutron capture in iron. The aluminum plug greatly decreased the fast neutron flux but had only a limited effect on the low energy neutron flux. The applicability of the albedo Monte Carlo calculational method to this problem was examined with the following conclusions: For ducts of small radius, the calculations overestimate the streaming because the albedo data were given for plane geometry. Low energy neutrons were underestimated by the calculation due to the neutron penetration through the cavity wall.