22 



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



The experiments were carried out with two increments of load, 

 namely from \ — 1 ton and 1 — 1 J tons. 



Table V contains the results both in differences of scale readings 

 and in increments of strain per half ton. 



The curves are plotted in fig. 5, and it will be seen that, whilst on 

 the tension side the two curves practically agree, on the compression 

 side the increment of strain is greater for the higher load. 



Fig. 5. 





■3-4 



. £ fi 1 Ton 

 k i n li Tons 



■ 2* 



Lateral Stxaih 



4- a 



■ /-2 « >> ^^^^ 



.3-4 «■ 



Relations between Stress and Lateral Strain. 



In order to appreciate the results of the foregoing experiments, and 

 to compare them with those which would be expected from purely 

 theoretical considerations, it became necessary to investigate the 

 relations which obtain between the lateral strain and the stress 

 producing it, in specimens under direct tensile and compressive forces. 



To obtain these relations for the material of the first cast-iron beam 

 specimens were cut from the less strained portions of the beam itself. 



The tensile piece was 1*956 cm. in diameter, and was of uniform 

 cross-section for a length of about 25*0 cm. The ends were screwed, 

 and gripped in the testing machine by the ordinary ball and socket 

 arrangements. 



The instrument used was very similar in principle to that employed 

 for measuring the lateral strain in the beams. It has been fully 

 explained and illustrated in a paper published in the 'Philosophical 

 Magazine ' (6th series, vol. vi, p. 417, October, 1903). 



The total magnification was 2744'5, and the load was advanced 

 J ton at a time. 



The lateral strain per J ton of load was then calculated by dividing 

 the difference of scale readings by 84540, and the corresponding- 

 stress was 169 "07 kilogrammes per square centimetre. 



The results are tabulated and reduced in Table VI (Appendix). 



