OF IRON BEAMS. 445 



made at Messrs. Hatton's foundry in Salford. 

 The intention was, to endeavour to ascertain 

 the relative proportion of the ribs in a cast iron 

 beam, to enable it to bear the most without 

 breaking, the thickness of the ribs and of the 

 middle part between them being invariable. 



For this purpose I got a model made of wood ; 

 the middle part of which was a uniform board, 

 3 inches deep, J inch thick and nearly 8 feet 

 long ; to the top and bottom edges of this board 

 there were nailed equal triangular ribs, of the 

 same thickness as the board ; the breadths of 

 the ribs being so disposed that the sum of the 

 top and bottom ribs in any cross section of the 

 model was always the same, and the ribs were 

 each just an inch broad in the middle of the 

 model, and varied toward the ends in all pro- 

 portions from equality to 8 to 1. 



The figures below are intended to represent, a 

 vertical plan of the model, its middle and end 

 sections, and an elevation or side view of it. 



•KOT. anr. 



ELEVATION. 



ZJ 



