274 Mr. G. Wilson. On a Method of detet 'mining the 



section at every point, but with a straight mean fibre, and hence the 

 method is applicable. 



Appendix. 



To find the magnitude of the reactions at the points of support of 

 a continuous girder of three spans (viz., 60 feet, 100 feet, and 

 40 feet respectively), and loaded with a uniform load of 3 tons per 

 foot run, the moment of inertia of the cross section being 2100 at the 

 commencement of the 60-foot span and increasing uniformly to 3300 

 at the commencement of the 100-foot span, and thence diminishing 

 uniformly to 3000 at the beginning of the 40-foot span, and further 

 diminishing uniformly to 2200 at the other end of the girder, the 

 units taken being feet and tons. 



The variation of the moment of inertia is shown in fig. 2. The 

 curve A BOA 3 in fig. 3 is the M/I curve for the beam resting on each 

 end support, and loaded with 3 tons per foot run. 



Treating this as a new load and reducing the ordinates in the 

 correct proportion, the curve A DEA 3 shows the amount of this load 

 transmitted to A to form the reaction there. 



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