A clustering-based sampling approach for refreshing search engine's database.

A walking machine comprises two pillars 8 and 11 normally resting on the ground and supporting a load 22 on a platform 21 eccentrically between the pillars. A lifting leg 5 is connected by means of ball joints to a foot and the platform and can be moved by means of two double acting hydraulic jacks to alter its inclination in two planes. In use the platform is first tilted by extending the lifting leg towards the load and at an angle. One of the jacks is then actuated to get the lifting leg vertical so that the platform drags at one end. The platform is then levelled and the process repeated for as many times as are necessary.