In the construction of modern metal airplanes there are many locations where a more or less concentrated load is transferred to a large area of material. Therefore the design-engineer is frequently confronted with the problem of “shear lag.” This problem can be treated in a few simple cases by the mathematical theory of elasticity, especially by Airy’s stress functions, but in many other cases, in order to avoid mathematical complexities, certain assumptions must be made which will simplify the analytical solution of the problem. These assumptions usually do not agree with the actual conditions therefore the results are not adequate. By the photoelastic method, however, the results obtained by the mathematical theory can be checked. It is the purpose of this experiment to check the results which have been obtained by the theoretical investigation for a few simple cases.