Safety scaffold

Claim 1

A SAFETY SCAFFOLD, COMPRISING: A PLANK STRUCTURE, CONTAINING AN OUTER PLANK MEMBER CONSTRUCTED OF FOLDED SHEET METAL HAVING A TOP SECTION INCLUDING A SUBSTANTIALLY ELONGATED RECTANGULAR TOP SURFACE WITH DEPENDING FLANGES EXTENDING DOWNWARD ON EACH SIDE THEREOF TO FORM A PAIR OF SIDE SECTIONS AND INNER FLANGES DISPOSED ALONG A BOTTOM TO DEFINE A SUBSTANTIALLY FLATTENED RECTANGULAR CROSSSECTION WITH A SUBSTANTIALLY OPEN BOTTOM, SAID INNER FLANGES BEING SECURED IN PARALLEL RELATION BY A PLURALITY OF STRAPS EXTENDING THEREBETWEEN, AN INNER PLANK MEMBER CONSTUCTED IN THE FORM OF A HOLLOW SHEET METAL UNIT OF SUBSTANTIALLY RECTANGULAR CROSS-SECTION AND FORMED WITH A TOP SECTION AND SIDE SECTIONS SIMILAR TO THE OUT PLANK MEMBER BUT SIZED TO FIT SLIDABLY WITHIN SAID OUTER MEMBER IN A SUFFICIENTLY TIGHT RELATION TO PREVENT LATERAL PLAY IN ANY DIRECTION, SAID TOP SECTION OF THE OUTER PLANK MEMBER INCLUDING A THIN EDGE ADAPTED TO FIT IN CLOSE RELATION TO THE TOP OF THE INNER PLANK MEMBER; A BACK RAIL, CONTAINING AN OUTER HOLLOW METAL BACK RAIL MEMBER OPEN AT ONE END, AND AN INNER HOLLOW METAL BACK RAIL MEMBER, SAID OUTER AND INNER MEMBERS HAVING SMOOTH SURFACES FITTING IN TIGHT SLIDABLE RELATION; AND BRACKETS FORMED FOR CARRYING THE PLANK STRUCTURE AND BACK RAIL STRUCTURE IN SUBSTANTIAL PARALLEL RELATIONSHIP, SAID BACK RAIL STRUCTURE BEING MOUNTED FOR TELESCOPING ADJUSTMENT INDEPENDENT OF THE ADJUSTMENT OF THE PLANK STRUCTURE.