to the column was here substituted for diagonal bracing , and the thrust of the main rib was conveyed to the second tier columns , which were firmly secured to small arched roofed girders , and connected to the first tier columns . The effect of this was to produce a transverse strain upon the… … standards . Pulleys and balance - weights were con nected to this rod at various points , by means of cords reaching nearly to the floor of the building . By this contrivance the opening or closing of the ventilator could be managed by simply turning the valve . The ridge consisted of a piece of…
