I'TII.ITY OK TMK TKST II A k, K'iV. 531
Benjamin, of the Case School of Applied Science, has shown that formulas used, prior to 1901 are unsuitcd and incorrect for figuring the strength of cast beams, etc.
The prevailing practice of recording tests to-day may, in some cases, where test bars not less than of one inch area are used, be accepted as an approximation in so far as relates to a firm's own practice in making comparisons for mixture, with permanent hands, but sin mid a firm desire to bring' in a new manager or tester, who has been guided in ruling's or records obtained from other shop practice or systems, his past experience will prove of very little value to him; hence the firm must lose in many ways before the new man is enabled to be rightly guided by information which he can deduce from his new system. Then, again, a manager or tester in making any changes from OIK' work to another is also a loser and is subjected to the same inconveniences, etc., just mentioned. This shows us thai lx>(h sides can lose some, saying- nothing as to what is lost by their not being able to make inlelligvnt romparisons with the outside foundry and engineering world, or with blast furnaces from which large quantities of pig metal must and should be intelligently purchased. Present practice shuts us up like a clam, and makes us dead to all the benefits which a standard of physical tests could insure*. Progression demands something" broader and of more eonvef utility than the practice of 1901 insures.
In reviewing tests recorded of test bars or castings in our engineering' text-books of the past, we find the practical utility of the same to be largely lost, for the reason that there is no base presented upon which to form ila.tr mixtures, to duplicate fairly the 4t grade " ofed standards seen in the next chapter., if they have not drawn '1