would be subject to attack and possible deterioration dovetail grooves may be formed in each segment edge and a long dovetail insert 71 may be pushed or driven through the length of the grooves from base end to apex end the dovetail insert may be of aluminum copper or plastic rather than wood for weather resistance fig1 and 16 show another system for drawing and holding the segments together a dome 75 shown here as not having an apex opening although it can have may be held together by a series of tension bolts or cables 76 for example three cables spaced at different levels as illustrated the cables pass through holes in each segment with the last several segments holes on one side of a joint 77 inclining slightly upwardly or downwardly so the ends 78 of the cable bolt can overlap as in fig1 the segment 11j in which the joint occurs can have a steel reinforcement plate 72 inlaid for bearing against by nuts 81 which draw the multiplicity of segments together into a tight circle nut tightening can be through access holes 82 in one face or the other of the dome a turnbuckle could be used in lieu of the nut and steel reinforcing plate 77 still hidden from view in the segment s this system gives the.