Abstract: The invention provides for a series of five related three-dimensional mechanical puzzle devices comprising of a real or imaginary spherical support element and a plurality of moveable interlocking shapes which can be manipulated around any of a number of distinct axes to assume a very high number of configurations. The external appearance of the devices are keyed so that the unique identity of each external segment can be determined and related to the global reference frame thus realising a series of puzzles which can be regarded as solved if the segments are positioned in a desirable rather than a undesirable configuration. The realisation of said devices via an electronic simulation.

Abstract: An extendable/retractable link apparatus 10 defines a fluid passage therethrough and may be connected between two relatively moveable components, e.g. an aircraft ejector seat and the adjacent fixed airframe, so that, when there is relative movement within pre-set limits, there is no significant displacement of fluid and no significant pressure force generated. The apparatus comprises a body 12 defining a fluid inlet/outlet port 16 and slidably receiving a piston 18 having a central bore which defines a fluid inlet/outlet port 24. The fluid passage is defined between said inlet and outlet ports 16 and 24. Relative movement of the piston 18 and the body 12 does not cause significant displacement of the fluid into or out of the fluid passage.