To avoid lateral drift of the batten as the lift lines pay out of the grooved drums, the helical groove orientation on the drums of the line shaft may be alternated between drums to balance competing fleet angles.
12.
The lowest parts of the four columns of Bernini's Baldachin have a helical groove, and the middle and upper sections of the columns are covered in olive and bay branches, which are populated with a myriad of bees and small putti.
