1.  Field of the Invention
This invention relates to a heat actuable directing device capable of moving a member to be directed to a more favoured disposition with respect to the source of heat, such as the sun, which actuates said device, should the source of heat move relative to said member.  The heat actuable directing device in accordance with the present invention preferably derives all its energy requirements from the source of heat which determines the favoured disposition. 
2.  Description of the Prior Art
With the current emphasis upon meeting energy requirements without resorting to the exploitation of oil or other fossil fuels, there is a growing interest in the use of solar energy.  To this end, many types of collectors have been devised and all are satisfactory to some extent or other.  It is fundamental however, when dealing with solar energy collection to realize that the amount of heat absorbed is totally dependent upon the area of the collection surface visible to the sun.  Accordingly, unless some means is provided to align solar collection devices to optimal dispositions with respect to the sun as the sun moves, the effective collection area, i.e. the area projected on to a plane normal to the sun's rays, would be well below the optimum for the actual surface area and cost of the particular solar energy collection device.  In the past means have been provided whereby backup energy sources are utilized to move solar energy collection devices with respect to the sun as it moves.  The programming of such movement has been controlled by such well known devices as photocells.  Less accurate devices have been devised which involve a timed movement.  All prior art methods, however, utilize a backup energy source and do not derive their energy requirements for aligning the member to be directed from the source of heat itself, e.g. in the case of solar energy collection, the sun.