The New Thoughts of Galileo

with another piece of wood, or some other hollow material, which serves to enclose the rope and the cylinder.

After this wrapping of filaments and fibers, by which one explains the texture that gives cylinders of wood and ropes such great resistance, he says that the avoidance of a void is the cause of the resistance of cylinders that have no fibers, beyond the natural glue that gathers and unites their parts.

As for the resistance on the part of the void, it is noticed in the difficulty one has when one pulls a piece of well-polished marble perpendicularly from another piece that is also polished: for the top piece carries and pulls with it the one underneath, which cannot separate from it because a void would be created, even if only for the short time required for the movement of the outside air to the middle of the piece: for example, if there is one foot from its extremities to the middle, the air would not employ a third of a minute to make this path; for its circles are naturally twenty-three feet in a third.