•20 



Mr. J. Morrow. On the Distribution of [Oct. 27, 



The general conclusions to be drawn from these curves are, firstly, 

 chat as the load increases, the increment of lateral strain in the outer 

 tensile layers becomes less, and that this is accompanied by a much 

 increased increment in the less stressed fibres nearer the neutral surface ; 

 and, second, that on the compression side, with higher loads, the 

 increment of lateral strain in the outer fibres increases. 



To what extent these actions take place before fracture can only be 

 inferred from the experimental results. The greatest changes occurred 

 between 2 and 2J tons, that is with a bending moment at the section 

 under observation of not more than four-fifths of that which the beam 

 was capable of resisting before fracture at the middle of the span ; and 

 between these limits the effects noticed would become much more 

 remarkable. 



The most striking fact brought out is, as will be seen later, that the 

 values of the strains thus obtained are considerably lower than would 

 be expected from theoretical considerations. 



This fact appeared so important that it was decided to further verify 

 the result by the examination of a second cast-iron beam. 



The beam used for this further investigation was 7*578 cm. deep 

 and 3*212 cm. broad. The span was 91*44 cm. as before, and the 

 section examined 37 cm. from one of the supports. Readings were 

 taken at the middle points of the depth and 1*2, 2*4, and 3 * 6 cm. 

 both above and below these points. 



The load was varied between J and 1 ton only. In all other 

 respects the procedure of the previous experiments was repeated. 



Table IV contains the results in differences of scale readings, the 

 first column showing the distance of the point under observation from 

 the middle of the depth. The curve is given in fig. 4. 



It will be shown that these results corroborate those obtained from 

 the beams previously described.. 



Experiments on Cast-iron Beam No. 2. 



Table IV. 



Position of 

 instrument. 



Differences of 

 scale readings. 



3*6 

 2*4 

 1*2 

 0-0 

 1*2 

 2-4 

 3*6 



+ 7*30 

 + 5-00 

 + 2*40 

 + 0*25 

 -1*97 

 -4*34 

 -6-28 



