There are two ways, and only two, in which we can find out what a machine is capable of doing. One of these is to try it out, to “put it through its paces” by using it for every sort of work which it is expected to perform and observing whether or not it does what we want it to do. The other way is to measure it (or to take the measurements of it as supplied by its responsible manufacturer) and compare these with the measurements of the essential parts of machines with the performance of which we are already familiar. Unless it is a brand-new type of machine, designed to do something that has never before been done by machinery, or to do it by a different mechanical method, there is obviously a great saving of time and money in buying a machine from specifications that insure the correct performance of its expected duty over the other plan of first buying the machine and then trying it out in practice to see whether it will do what we want done. The manufacturer or business man who would purchase machinery of any sort without first making certain that its dimensions, speeds, weight, power-consumption, controls, and the materials used in its construction were such as to adapt it precisely to the work he expected to do with it would speedily bankrupt his business. It takes but a moment’s thought for the reader to prove this to himself. On the other hand, however, we find business men constantly employing men and women to perform specific duties without applying any tests or measurements, other than the most rudimentary ones, to determine in advance whether the person so employed is fitted for the work he or she is expected to do. And as every employer knows, one of the most costly wastes in almost every business or manufacturing establishment is the expense of constantly “breaking in” new employees to take the places of those who have left or have been dismissed because they were found, after trial, not to be fitted for the duties to be done.