Computer simulation and flow visualization were conducted to study thermocapillary flow in a small zone of silicone oil held between two differentially heated rods. Despite significant zone necking, converting calculated streamlines to flow patterns that could be compared with the observed flow patterns was possible, by incorporating the lens effect of the oil zone. It was found that the lens effect causes the streamlines to appear to shift toward the free surface and away from the top and bottom of the zone. It also causes the vortex to appear to shift upward and outward. The calculated and converted flow patterns agree very well with the observed ones.