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.

A paper on “Flapping Flight of Aeroplanes ” by the present writer was communicated by the late Professor G. F. FitzGerald to the “ Proceedings ” of the Royal Society (Vol. 64, pp. 420-430) in 1899. At that date much that is now almost common knowledge concerning the mechanics of flight was little thought of, much less understood, practical aviation did not exist, and a limited supply of experimental results presented confusing specimens of discordant and unreliable data to the inquirer. The development, during the last eight years, of the practice and science of aviation, seems to justify a review of the paper1 of 1899 in the light of better information, and of a better understanding of the influence of head resistance and other things, ignored fifteen years ago.

I owe the greater part of the following information about the flight of the albatross to Captain E. H. Gordon, of the P. and O. ss. Company. He has studied these birds during numerous voyages, both on steamers and sailing ships. He has seen them near Cape Horn, the Cape, off the south coast of Australia, and at many other places.