Abstract
Results of heat transfer measurements in a differentially heated annulus of fluid for both the non-rotating and rotating cases are given. (In the latter case the flow is in the upper symmetric regime.) In all cases the upper surface of the fluid is free. The non-rotating heat transfer is essentially the same as that of vertical slot convection, whereas rotation modifies the heat transfer; the resulting main effects appear to be exerted through a decrease in the Ekman layer thickness.