228 



REPORT 1876. 



showing curved fractures ha^e broken at points more or less removed from centre 

 of span, and that in general the curve of fracture increases with distance of fracture 

 from centre. 



In all cases the fractured parts were found to fit exactly together, no piece of the 

 metal being thrown out on fracture talcing place ; and where the fractures were 

 curved the line of fracture pointed towards point of application of load, the results 

 of several experiments showing that fracture commences at the convex side of the 

 bar and passes upwards, gradually curving towards centre of span. 



The curved fractures occur also in bars of 1 square inch section, their forms not 

 being, however, so well marked as in the bars already referred to. 



With a view to obtain the relati\ e strength of bars showing straight and curved 

 fractures, a note was kept of the hreaking loads, deflection, forms, and positions of 

 fracture, the result of which is given in Table I. 



(The results given in ths following Tables are all from bars of 2 inches deep, 

 1 inch broad, and 36 inches span.) 



Table I. 



The above results show a slight excess of strength in bars breaking at centre of 

 span and with straight fractures. 



In general the deflections were found to increase with increase of load ; but in 

 some cases, the bars being exceptionally strong and remaining unbroken, a decrease 

 of deflection accompanied an increase of load. 



The results obtained from 14 such bars are shown in Table II. 



Table II. 



Average results obtained from 14 unbroken bars with increasing Loads. 



Loads to which bar was subjected . . 3360 lb. 3930 lb. 4480 lb. 



Average deflections at these loads ... . -327 in. '317 in. -313 in. 



Table III. contains the results of some experiments made to determine the 

 amount of " set " which took place in bars when subjected to several applications 

 of the same load. 



Table III. 

 Load applied 2800 lb. 



