String of pearls

Let a fine jet of water pour on a finger held about two inches under the tap. If you look carefully, you will see a strange wave-like pattern in the water. If you bring your finger closer to the tap, the waves become continuously more ball-shaped, until the water jet resembles a string of pearls. It is so strongly obstructed by the finger that because of its surface tension - the force that holds the water particles together - it separates into round droplets. If you take your finger further away from the tap, the falling speed of the water becomes greater, and the drop formation is less clear.