Another method is to shore the central standard from the foundation, as in [fig. 3.]
The legs in this manner can be made to support a platform up to 120 feet in height.
The required height having been reached, the legs are connected by trussed beams in the following manner: Two balk timbers of about 12 in. by 8 in. are laid immediately above each other between the king leg and each queen leg, resting on the two top transoms, as shown in [fig. 1.] They are from 6 to 9 feet apart, the top bay being sometimes made slightly lower than the others.
The lower balks are connected to the centre standard of the king leg by wrought-iron straps.
Fig. 2.—Plan of King Leg
A, Central Standard.
B, Shorings.
Fig. 3.—Showing Shoring to Central Standard
The top balks project from 6 to 10 feet beyond the king leg, and are halved at their point of intersection. The projecting ends are connected to each other by pieces 8 in. by 6 in., and again to the return balk by similar pieces (see [fig. 4]). They are also supported by struts from the central standard, as shown in [fig. 1.] The upper and lower balks are connected by iron bolts about 10 feet apart, and each bay thus formed is cross-braced in the same manner as the legs.
The iron bolts are covered by pieces of the same scantling as the braces.