This is an investigation of the distribution of the local rate of mass transfer from 4.2-in-diam naphthalene cylinders to air at ordinary temperature and pressure, flowing normal to the axis. The air speeds are near and within the critical zone of the drag. The results in the laminar region are compared with approximate boundary-layer calculations of H. Schuh and of H. J. Merk and with corresponding heat and mass-transfer experimentation in the literature. It is shown that the calculations after Merk are reliable from the point of stagnation to the predicted point of separation.