23 IRON ROOFS . width to resist the thrust which is conveyed through the gallery girders to the outer walls . The roof cost 12 £ . 15s . per square , exclusive of erection and covering . The roof over the Coventry Fig . 34 . … Market Hall , designed by Messrs . Coe and Robinson ( see Figure 36 ) , is in a single span of 90 feet springing from the ground , and constructed somewhat similarly to the main roof of the Agricultural Hall . The centre of the top of the arch is 45 feet above the ground , and the thrust of Fig .…
