] \ / f ANY studies have been made of the elastic be^-*havior of the structure of airplane wings and a number of theories have been advanced as a result of these studies. In general, however, it may be said that too little attention has been directed in these studies to the properties of the shear webs and their relative importance in defining the elastic properties of the structure. It was with this end in view that the investigation described in this paper was undertaken. Tests were made at the University of Michigan of several aluminum alloy box beams having dissimilar front and rear shear webs, and the results have been compared with those obtained by theory. These tests were conducted with the cooperation of the National Advisory Committee for Aeronautics and are presented here by the permission of that Committee. At the present time designers using the elastic axis method for the stress analysis of their wing beams are unable to predict accurately the exact location of this factor. Full-scale tests are frequently necessary to establish its position. It was found that an accurate prediction of the elastic properties of a simple rectangular box beam can be made. Theoretical results are in error principally due to a limited knowledge of the shear deflection characteristics of the webs. The influence and importance of additional knowledge concerning the shear webs themselves is definitely shown.