Abstract: A tower is located within a tube and is arranged to displace a liquid, which preferably is water. The tower may be arranged to float in the water and its buoyancy is controlled to cause movement of the tower relative to the tube. An observation gallery may be is carried at the top of the tower for carrying passengers, being arranged to rotate relative to the tower. As the tower floats in water, and the volume of tower structure which moves out of the water is minimal, the amount of energy required to move it from the bottom of the tube to its highest position may be made relatively small.

Abstract: A weighing hopper (20) comprising: a body portion for containing articles; a port in the body portion; a door (21) pivotally connected to the body portion for rotation about a first axis (A) between a first position in which the port is closed by the door (21) to retain articles in the body portion and a second position in which articles contained in the hopper (20) can be discharged through the port; and a mechanism (23) for moving the door (21) between its first and second positions comprising a first member (58) rigidly connected to the door (21); a second member (60) pivotally connected to the first member (58) for rotation about a second axis (E) parallel to and spaced from the first axis (A); and a third member (62) pivotally connected to the second member (60) for rotation about a third axis (B) parallel to and spaced from the second axis (E), and pivotally connected to the body portion for rotation about a fourth axis (C) parallel to and fixedly spaced from the first axis (A) so that rotation of the t