O of the important factors in the design of a compression member is its end fixity, for, as long as the slenderness ratio of a member is reasonably large, the load-carrying ability of the member is directly proportional to its end fixity. I t is unfortunate that the few cases in which the end fixity is definitely known (theoretically) seldom occur in practice. The commonly known theoretical cases are: pin-ended columns where the end-fixity coefficient is 1.0, built-in ends where the end fixity is 4.0, and the case of one fixed end and the other pin ended which has an end fixity of 2.04. These three cases never actually occur in practice, since in pinended columns there is always some friction present, and built-in ends are not infinitely rigid. In a few cases of elastically built-in columns, the end fixity can be calculated theoretically, but in general the designer of an airplane does not know the conditions of the ends of his members accurately enough to be able to use these means. Until the present time the designer has had to estimate the end fixity of various panels or columns because he could not take into account the effect of clips, eccentric loading, flexibility of ribs, bulkheads, or edge restraints. I t is the object of this paper to present a method whereby the actual end fixity of a member on an airplane or in a test assembly can be determined experimentally without failing the member. Engesser's modified Euler equation for both long and short columns is