These experiments were carried out in the aerodynamical laboratory at East London College, with a view to investigating the variation of air resistance of certain bars as the inclination of their longitudinal axes to the direction of the wind was varied, the current of air being kept at a constant velocity. Four bars were used, having the cross sections shown in Fig. I, that is, a square, a 2:1

rectangle, a circle, and a 3:1 streamline form. The bars were carefully made in wood to an equal length of 34m. and approximately a maximum width of lin. in each case. It was thought that interference due to the ends of the bars would be minimised by having some sort of entering edge fitted to the flats. Accordingly, wedge-shaped ends were tried in the case of a fifth bar, but various difficulties seemed to lead to erroneous results and they were abandoned in favour of squared-off ends.