The following examples do not take up the discussion of viewpoints to be heeded in determining the design of a framework for given external conditions. Rather they are methods for determining the forces in airplane fuselages and wings, though similar considerations are applied to certain simple cases of a different kind. The object of this treatise is to summarize and amplify these considerations from definite viewpoints.

Autogenous welding is discussed and various methods of testing those welds are presented.

"The present paper treats less of the effect of the union (of spars and ribs, namely, the reduction of the bending moment at the fixed ends of the spars) than of its influence on the torsional rigidity of the wing. The calculations are carried out for a two-spar wing of constant cross section, in which the ribs are replaced by a continuous member of constant rigidity" (p. 1).

Even before the publication of the results of the Gottingen experiments on the removal of the boundary layer by suction, experiments with nozzle-slotted wings were begun. A report of those experiments will be given here. Taken collectively, the experiments show that, as regards increasing the lift values, the effect of the air flowing from the nozzle-shaped slots is similar to the effect produced in the case of ordinary slotted wings. The high lift values are attained, however, at the smaller angles of attack employed in ordinary flight.