The Astronomical Tide-Producing Forces: General Considerations At the surface of the earth, the earth's force of gravitational attraction acts in a direction inward toward its center of mass, and thus holds the ocean water confined to this surface.
(the earth's force of gravitational attraction acts in a direction inward toward its center of mass; holds; the ocean water confined to this surface) (the ocean water; confined; to this surface)
the earth's force of gravitational attraction acts in a direction inward toward its center of mass the ocean water
holds confined
the ocean water confined to this surface
to this surface