INTRODUCTION TO AERODYNAMIC MEASUREMENT TECHNOLOGY SPECIAL SECTION

In physical science a first essential step in the direction of learnin g any subject is to find principles of numerical reckoning and methods for practicably measuring some quantity connected with it. I often sa y that when you can measure what you are speaking about, and express i t in numbers, you know something about it; when you cannot express it in numbers, your knowledge is of a meager and unsatisfactory kind; it may be the beginning of knowledge, but you have scarcely, in your thou ghts, advanced to the stage of science, whatever the matter may be.