In the first part of the report, an analytical method for determining the profiles of two-dimensional convergent nozzles is described. The complex potential of an infinite number of equal sources, distributed on the equally spaced lines parallel to a two-dimensional uniform flow, is obtained. The stream lines which surround the flow from each source are used as the profile of a convergent nozzle. Several types of the nozzle profiles and their velocity and pressure distributions are shown. In the latter part, experimental studies on the flow patterns for the two typical profiles of convergent nozzles are presented. Good agreement between the measured and calculated values of the velocity and pressure distributions was obtained. Observations were made on the stream lines and flow in the boundary layer along the nozzle walls, which were visualized by using evaporated-gas-oil smoke. The generation of vortices, with streamwise axes and sectional forms alike to those of mushrooms, was observed. The effects of the nozzle profile, the thickness of the upstream boundary layer and the use of a screen at the entrance section of the nozzle on the magnitude of vortices were examined.