An important problem confronting the designer of machines and structures which may be subjected to suddenly applied loads is the determination of the actual forces which the members must withstand. This investigation has been confined to a study of impact forces on beams in simple flexure. Margerum (American Society of Testing Materials, 1922) suggested a method whereby the maximum load might be found by obtaining indentations on a calibration bar attached to the moving head of the impact machine, and suggested using this in conjunction with an autographic stress strain diagram. Tests have been made upon both notched and unnotched bars, but the results were not satisfactory. It has been proposed that an accelerometer be designed with which the acceleration could be measured directly. After the acceleration is known the force producing the acceleration can be calculated. The acceleration of a point can be determined by a double differentiation of a space-time diagram. This method is being employed in this thesis. / M.S.