in the following description , specific details are set forth in order to provide a thorough understanding of the invention . however , it will be apparent that the invention may be practiced without these specific details . the present invention teaches an improved mud sill 1 having a foot 2 that is easy to install and remove with a minimal amount of labor required . the improved mud sill attaches securely as to the baseplate 20 of a screw jack 24 on a vertical member on a scaffolding assembly without the use of extraneous fasteners , such as nails or screws , as shown in the prior art uses in fig1 a and 1b to increase the supporting area bounded by the peripheral edge of the foot compared to the area bounded by the peripheral area of the baseplate . the improved mud sill 1 of fig2 is generally disk shaped with top surface 1 a and a bottom surface 1 b and an axis extending between the top surface and the bottom surface . a multi - layered /- part recess 3 is provided in the improved mud sill to receive a baseplate 20 axially with the foot 2 and baseplate 20 in a first relative angular orientation with respect to a vertical axis and then the improved mud sill is rotated around the vertical axis relative to the baseplate 20 to place the foot 2 and baseplate 20 in a second relative angular orientation to secure the baseplate 20 in place . once installed the improved mud sill of this important invention is restricted three dimensionally to the baseplate and yet it can easily be removed by a counter - rotation from the installation process . no nails or tools are required . without departing from the generality of the invention disclosed herein and without limiting the scope of the invention , the discussion that follows , will refer to the invention as depicted in the drawing . according to one embodiment of the invention , an improved mud sill 1 , for use with a generally horizontal baseplate 20 of a base of a vertical scaffolding member 22 , that is in turn part of a scaffold assembly as shown in fig1 b , is taught comprising a foot 2 with a transverse dimension measured in all directions that is substantially greater than each dimension in a parallel direction of the generally horizontal baseplate 20 , and with a top surface that has an opening , a bottom surface , and an axial dimension , measured between the top surface 1 a and the bottom surface 1 b , that is perpendicular to the transverse dimension of the foot 2 . the top surface 1 a has an internal peripheral edge 4 a defining the opening 4 and a recess 3 extends axially from the opening 4 . the recess 3 is suitably sized to receive the baseplate 20 of the scaffolding member 22 , so that the baseplate 20 can be disposed in the recess 3 of the foot 2 and the weight of the vertical scaffolding member 22 is directed against the mud sill 1 that distributes the weight forces over the area of the mud sill bearing on the subjacent surface 10 . preferably , a drain hole 5 extends from a lower surface 3 a of the recess 3 to the bottom surface 1 b of the foot 2 . a preferred opening 4 has a transverse dimension measured in all directions that is greater than each dimension in a parallel direction of the generally horizontal baseplate 20 . moreover , the recess 3 may comprise a first axial layer 7 defined by an upper surface having the internal peripheral edge 4 a of the opening 4 , a first lower surface 7 b having a peripheral edge , and an inner wall portion 6 bounding a first recess part and having an upper edge connected to the internal peripheral edge 4 a of the opening 4 and a lower edge connected to the peripheral edge of the first lower surface 7 b . the first recess part in the first axial layer 7 may have a transverse shape corresponding nominally to the transverse shape of the baseplate 20 so that the foot 2 and baseplate 20 interact to limit relative turning between the foot 2 and baseplate 20 . the peripheral transverse shape of the first axial layer 7 may correspond to the peripheral transverse shape of the baseplate 20 . additionally , the recess 3 may have a plurality of axial layers of varying transverse dimensions , so that the baseplate 20 can be inserted past the first recess part bounded by the wall portion 6 on the first axial layer 7 into a second recess part bounded by a second wall portion on a second axial layer 8 at a pre - determined axial depth and rotated in the second axial layer to secure the baseplate axially in said recess 3 . preferably , the second axial layer 8 has the shape of a circular disk . in the preferred embodiment shown in fig3 - 7 and 10 - 11 , the recess 3 has a second axial layer 8 comprising at least one radial recess part 3 disposed axially at a predetermined distance from the top surface 1 a of the foot 2 . the at least one radial recess 3 has an axial dimension greater than the thickness of the baseplate 20 between oppositely facing , and parallel , flat surfaces and has a radial dimension that is greater than a maximum transverse dimension of the baseplate , so that when the baseplate is inserted into the recess 3 and aligned with the second recess part in the axial layer 8 , the baseplate 20 can be rotated freely through 360 ° in the recess 3 to secure the baseplate axially in said recess 3 by placing the upwardly facing surface of the baseplate 20 in confronting relationship with a parallel flat surface on the foot 2 . moreover , the second axial layer 8 of the recess 3 may have at least one protuberance 8 a in the path of a rotating baseplate 20 to restrict the rotation of the baseplate within the second axial layer 8 of the recess 3 to limit movement of the baseplate rotationally in said recess 3 , as shown in fig1 and 11 . in one embodiment , as shown in fig3 - 7 and 10 - 11 , the recess 3 may have a third axial layer 9 comprising at least a third radial recess part 3 disposed axially between the second axial layer and the lower surface of the recess 3 . the third axial layer 9 preferably has a transverse shape corresponding to the transverse shape of the baseplate 20 and the third axial layer is axially aligned with the first axial layer 7 and the second axial layer 8 , and said third axial layer 9 is rotatingly nonaligned with the first axial layer to limit axial and rotational movement of the baseplate in said recess 3 . the peripheral wall portion on the layer 9 bounding the third recess part and the baseplate interact to limit relative turning of the foot 2 and baseplate 20 around a vertical axis . referring to fig8 , the bottom surface 1 a of the foot 2 may be convex , allowing the weight of the vertical scaffolding member 22 to be distributed perpendicularly to the tangent of the convex bottom surface of the foot 2 so that the scaffolding member 22 can be laterally restrained at its base . this embodiment is particularly well suited to soft soil conditions . another preferred embodiment of the improved mud sill 1 , for use with a generally horizontal baseplate 20 of a base of a vertical scaffolding member 22 , comprises a foot 2 , having a transverse dimension measured in all directions that is substantially greater than each dimension in a parallel direction of the generally horizontal baseplate 20 , with a top surface that has an opening 4 , a bottom surface 1 b , and an axial dimension , measured between the top surface and the bottom surface , that is perpendicular to the transverse dimension of the foot 2 . the top surface has an internal peripheral edge defining the opening 4 . the opening has a transverse dimension measured in all directions that is greater than each dimension in a parallel direction of the generally horizontal baseplate 20 and a recess 3 extends axially from the opening with a drain hole 5 extends from a lower surface of the recess to the bottom surface of the foot 2 . the recess is suitably sized to receive the baseplate 20 of the scaffolding member 22 , so that the baseplate can be disposed in the recess 3 of the foot 2 and the weight of the vertical scaffolding member can be distributed over the transverse dimension of the foot of the mud sill 1 . referring to fig9 , the recess 3 may comprise a first axial layer 7 defined by an upper surface 7 a having the internal peripheral edge of the opening 4 , a first lower surface 7 b having a peripheral edge , and an inner wall 6 having an upper edge connected to the internal peripheral edge of the opening and a lower edge connected to the peripheral edge of the lower surface . in one embodiment , as shown in fig1 , the improved mud sill 1 , for use with a generally horizontal baseplate 20 of a base of a vertical scaffolding member 22 of a scaffolding system with a predetermined distance between the vertical scaffolding members , comprises an elongated foot 2 , having a longitudinal dimension that is greater than the predetermined distance between the vertical scaffolding members and a transverse dimension measured in all directions that is substantially greater than each dimension in a parallel direction of the generally horizontal baseplate 20 , with a top surface that has at least one opening 4 , a bottom surface , and an axial dimension , measured between the top surface and the bottom surface , that is perpendicular to the longitudinal dimension of the foot 2 . the top surface has an internal edge defining each of the at least one opening 4 , each opening having a transverse dimension measured in all directions that is greater than each dimension in a parallel direction of the generally horizontal baseplate 20 with a recess 3 extending axially from each opening 4 . each said recess 3 is suitably sized to receive at least one baseplate of the scaffolding member 22 , in this way , at least one baseplate can be disposed in the recess 3 of each opening of the foot 2 and the weight of each vertical scaffolding member associated with each at least one baseplate can be distributed over the transverse dimension of the foot 2 of the mud sill 1 . in another embodiment , as shown in fig1 , the elongated foot 2 has a plurality of openings , each opening 4 being spaced from one another at the predetermined distance . in yet another embodiment the opening 4 comprises an elongated trough extending longitudinally along at least a substantial portion of the elongated foot 2 . a drain hole 5 may extend from a lower surface of the recess 3 to the bottom surface of the foot 2 . according to one embodiment of this important invention , an improved screw jack 24 , as shown in fig6 , is taught with a generally horizontal baseplate 20 secured to a bottom end of an externally threaded screw 26 and an internally threaded wing nut 28 , for use with a base of a vertical scaffolding member 22 that can rest on the wing nut 28 , the screw jack comprising a mud sill 1 , having a transverse dimension measured in all directions that is substantially greater than each dimension in a parallel direction of the generally horizontal baseplate 20 , with a top surface 1 a that has an opening 4 , a bottom surface 1 b , and an axial dimension , measured between the top surface and the bottom surface , that is perpendicular to the transverse dimension of the mud sill 1 . the top surface has an internal peripheral edge 4 a defining the opening 4 and a recess 3 extends axially from the opening 4 . the recess 3 is suitably sized to receive the baseplate of the scaffolding member 22 , so that a top end 26 a of the moveable screw 26 can be inserted into the base of a vertical scaffolding member 22 and the generally horizontal baseplate 20 can be disposed in the recess 3 of the mud sill 1 and the weight of the vertical scaffolding member can be distributed over the transverse dimension of the mud sill 1 . preferably , a drain hole 5 extends from a lower surface 3 a of the recess 3 to the bottom surface of the foot 2 . as shown in fig5 a - 5c , the opening 4 has a transverse dimension measured in all directions that is greater than each dimension in a parallel direction of the generally horizontal baseplate 20 . according to one aspect of the invention , the recess 3 comprises a first axial layer 7 defined by an upper surface 7 a having the internal peripheral edge 4 a of the opening 4 , a first lower surface having a peripheral edge , and an inner wall having an upper edge connected to the internal peripheral edge of the opening 4 and a lower edge connected to the peripheral edge of the lower surface . the mud sill 1 or foot 2 can be made of suitable materials , including wood , plastic or other hard material . it can be constructed in layers , as shown in fig7 , and fastened together with a fastener including a water insoluble adhesive . for mud sills having a uniform recess 3 , a simple boring process can be employed to make the recess 3 . while this invention has been described in connection with the best mode presently contemplated by the inventor for carrying out his invention , the preferred embodiments described and shown are for purposes of illustration only , and are not to be construed as constituting any limitations of the invention . modifications will be obvious to those skilled in the art , and all modifications that do not depart from the spirit of the invention are intended to be included within the scope of the appended claims . those skilled in the art will appreciate that the conception upon which this disclosure is based , may readily be utilized as a basis for the designing of other structures , methods and systems for carrying out the several purposes of the present invention . it is important , therefore , that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention . my invention resides not in any one of these features per se , but rather in the particular combinations of some or all of them herein disclosed and claimed and it is distinguished from the prior art in these particular combinations of some or all of its structures for the functions specified . with respect to the above description then , it is to be realized that the optimum dimensional relationships for the parts of the invention , including variations in size , materials , shape , form , function and manner of operation , assembly and use , and all equivalent relationships to those illustrated in the drawings and described in the specification , that would be deemed readily apparent and obvious to one skilled in the art , are intended to be encompassed by the present invention . therefore , the foregoing is considered as illustrative only of the principles of the invention . further , since numerous modifications and changes will readily occur to those skilled in the art , it is not desired to limit the invention to the exact construction and operation shown and described , and accordingly , all suitable modifications and equivalents may be resorted to , falling within the scope of the invention .