HIGH-STRENGTH PLASTICS

of changes in length of some two feet. These springs and the cable are mounted in permanent tension, and a large truck-type automotive shock absorber is installed across the springs. Again the damping of these absorbers is chosen so that their energy dissipation is somewhat greater than the expected energy input from the vortices, assuming a coefficient CK = 1. In conclusion it can be stated that welded steel stacks of the size described or larger stacks are unsafe, and that dampers or other means of suppressing the vibrations are essential.