the outer ring by screw threads and having support for a manhole cover the lower surface of the frame assembly has a part spherically curved surface resting on a similarly curved surface of the manhole basin upper section and which allows the orientation of the frame assembly to be adjusted also the frame assembly itself may have parts with part spherical mating surfaces allowing an upper part to be adjusted for slope when the remainder of the frame assembly has been fixed application_number US 93572301 A description fig1 shows a manhole cover 10 supported on the top section 12 of a manhole basin by a manhole cover frame assembly 14 which is adjustable in accordance with this invention the manhole basin of which the top precast section 12 is shown in fig1 is cast of concrete and has a cylindrical middle section 16 the top portion of which is shown and which rests on a lower section which is not shown the top section 12 rests telescopingly on the middle section 16 the invention allows adjustment of the height and slope of the cover 10 relative to the ground level g the frame assembly 14 in common with some prior art designs has two parts formed of cast metal firstly an inner upper ring part 20 having an internal flange 22 providing a recess for the edge of the manhole cover 10 and having a surrounding helical thread 23 and secondly an outer lower ring part 24 having an internal helical thread 24 a which.