MERCA
The Magic Energy Resonance and Collimation Amplifier. (MERCA)
The MERCA used in the books is a development of a desktop toy which used to be popular with society witches in Victorian times. The toy consists of two hemispherical geodes mounted with their open faces aligned with each other. When a witch places a finger between the two, the finger will glow brightly when seen with the witch's magical sense. The effect is due to the focussing effect of the thousands of tiny crystals which line the interiors of each half-geode.
The Full Scale MERCA in the Phoenix uses the same principle. A cutaway drawing is shown to scale in the image. The initial build was static and was secreted in the basement of a theatre in the West End. Since the directed beam technology had not been developed the unit had to be built big enough to contain its victims.
As with all MERCAs the magical energy source is most often life-force provided by sacrifice.
To produce a sustainable amplification effect, the second geode is replaced with an array of large crystals which are fed from a circumferential arrays of smaller crystals. These act as magical energy directors and reflectors feeding the magical energy back to the focus of the crystal-lined hemisphere suspended above them. The loop formed creates a resonance, building up the magical field until it reaches an energy level which can either burst through the crystals containment or be absorbed into an object placed at the focus. The energy can reach levels which can create powerful magical artefacts such as god-stones.
In The Quicksilver Wyrm, the technology has moved on and smaller but more powerful versions of the MERCA have been developed. The table-top version shown here can produce an intense beam of controlled concentrated magic. This is achieved by the linearising crystals and the crystal lined focus rings added to the device. Even small animal sacrifices can produce significant results.
