[en] Isotopic series of 58 neutron-deficient secondary projectiles (^205,206At, ^205-209Rn, ^{208-212,217,218}Fr, ^211-223Ra, ^215-226Ac, ^221-229Th, ^226-231Pa, ^231-234U) were produced by projectile fragmentation using a 1 A GeV ²³⁸U beam. Cross sections of fission induced by nuclear and electromagnetic interactions in a secondary lead target were measured. They were found to vary smoothly as a function of proton and neutron number of the fissioning system, also for nuclei with large ground-state shell effects near the 126-neutron shell. No stabilization against fission was observed for these nuclei at low excitation energies. Consequences for the expectations on the production cross sections of super-heavy nuclei are discussed