MECHANICAL TESTING OF IRON AND STEEL. 227 



produce any appreciable effect on the results recorded in 

 such testing. 



Should the metric system become compulsory it would 

 certainly be advisable to try and obtain an international 

 agreement as to the leading dimensions for ordinary test 

 bars. 



Next as to the observations which should be carried out 

 and recorded. Every test record sheet should have a column 

 in which could be briefly recorded the past treatment of the 

 specimen, such as whether it had been turned down or 

 forged down to size, whether sheared off, annealed, and so 

 forth, for without some such brief history it is almost im- 

 possible to properly interpret the test records. 



The original dimensions should be given, the Yield Point 

 as determined by the steelyard drop, and the maximum 

 load carried with the ratio of these two, both of course 

 expressed in pounds or tons on the square inch ; also the 

 whole extension expressed as a percentage of the whole 

 original length, and the extension on the two inches or one 

 inch which includes the point of fracture (according to the 

 original length of the bar) also expressed as a percentage ; 

 lastly, the reduction of area per cent., meaning by this the 

 ratio of the lost area to the oriofinal. These observations 

 are perfectly easily recorded in every test, and with no more 

 time spent, as repeated experience has convinced me, than 

 when some of them are omitted. Finally, I would have the 

 work spent in fracturing the bar, calculated as above, per 

 cubic inch, entered on the record sheet, and a brief note as 

 to the condition of the fractured surfaces. 



With figures such as these before him from the test 

 house, with similarly carefully recorded results of the im- 

 pact and bending tests, no engineer would have the least 

 difficulty in coming to a decision as to the value of the 

 material the maker was supplying to him, nor would he ever 

 have the slightest future cause for anxiety in regard to any 

 material which had successfully passed the ordeal. Checked 

 by the chemical analvsis the maker too would know the 

 lines on which he was working, and how and where he 

 could improve the quality of the material he was putting on 



