Complex sentence: After successful experimentation with the sheathing Muntz also took out a patent for bolts of the same composition and these also proved a success, for not only were they cheaper they were also very strong and lasted longer.
Split into simpler sentences: After successful experimentation with the sheathing Muntz also took out a patent for bolts of the same composition. These too proved a success as they not only were cheaper but also very strong and lasted longer.