The cauldron is used for many different purposes in magick and ritual.  It is a source of wisdom, and can be used for scrying and in any number of ways during sabbat rituals and can hold water, fire, incense or flowers.

 

The Cauldron is usually a three legged vessel, ideally made of iron and has the opening smaller than the body of the cauldron, ideally with a stout carrying handle.

 

The Cauldron is the tool of the West, and is associated with Water, and is feminine in nature, it represents the Goddess and fertility.  Leaping over the Cauldron is a known fertility rite.