FORMS OF TEST BARS 



307 



material, which was mild steel. All the others were of 

 the same material. In the bar B two small saw-cuts 

 were made, the bar was got to almost a welding heat, 

 and the nicks closed up, so that they were to all intents 

 and purposes hidden cracks in the material. Under the 

 test the strength of the remaining material was not so 

 much reduced as might have been supposed. Two bars 

 of the form C were tested, one held in the ordinary way, 

 and the other held in the machine by pins, both bars 

 being nicked on one side only. The test in this case 

 showed a considerable reduction on the original strength 





o 



FIG. 157. BAKER'S TESTS. EXPERIMENTAL BARS. 



of the steel, the bar held by the pin giving the lower 

 results. D and E are similar to Mr. Stromeyer's bars 

 already referred to (Fig. 156), except that in E two saw-cuts 

 were made in the side of the hole. The bar marked F 

 was first bent several times at a blue heat and afterwards 

 tested. 



The breaking stresses for these bars are given in the 

 following table : 



