The picture above is a page from the book, Mechanical Laboratory Methods (Smallwood and Keator, 1931), that I discovered in my very favorite used book store, MacKay’s in Chattanooga, TN.  The book, written for Engineering students, begins with the statement, “The science of experimental engineering rests primarily upon the art of measurement.  Conclusions relating to general laws or specific operating conditions, formed from test results, stand or fall according to the accuracy of measurements” and they conclude, “there is no such thing as absolute accuracy of measurement except by accident.”