2.  A round ball of quartz crystal or glass used as focal point in skrying. Gazing at the ball, one enters into a trance-like state where dream like scenes and symbols are seen and interpreted. Similar aids are the Magic Mirror, a pool of black ink, a piece of obsidian.

Suggested Reading:

• Crystal Balls & Crystal Bowls, Tools for Ancient Scrying & Modern Seership, by Ted Andrews
• Divination for Beginners: Reading the Past, Present & Future, by Scott Cunningham