Journal of the Society of Motion Picture Engineers (1930-1949)

measure 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 thoughts, advanced to the stage of science, whatever the matter may be." This observation is probably more important today than it was sixty years ago, because our apparatus and systems have become more and more complex and operate faster and faster. One of the most important of our relatively new measuring tools is high-speed photography. The use of high-speed photography in research and development work leading to new devices and new systems and in understanding older devices, is becoming increasingly important. In our own organization we have established a regular service for the use of engineers, which is readily available, in the form of a variety of good equipment and skilled people to operate the equipment. As measurements are taken of apparatus or systems we frequently change our ideas of how and why devices act as they do. I can think of no other tool available to the engineer which has caused him to change his view of things as much as high-speed photography. Intuition is a valuable human trait but it may easily lead us astray in engineering matters. It has been said that our troubles are not always due to facts we do not know but frequently to those things that we are sure are true but which are in reality untrue. This applies particularly to those things which operate so fast that they cannot be seen or judged by the naked eye. High-speed photography extends our limited human powers of observation. It not only expands time so that we can readily see what happens in extremely short periods of time but it also makes possible the quantitative measurement of these effects. High-speed photography itself is a broad field of activity and has been covered in many excellent papers which have appeared in the Journal of this Society. However, for the application to research and development work, it is important to know that high-speed photography is capable of expanding time for mechanical or electrical effects, or for both at the same time. It can be used to study fast complex mechanical motions and it can also be used to study cathode-ray oscilloscope traces of high speed. The ability to do these things quantitatively has an important economic value. The economic value of the use of high-speed photography comes about in two major ways: 1 . As a saving in manhours of engineering effort by doing a job with fewer men, or — more likely — by doing more jobs with the same men; and 2. As savings in materials, devices or systems either by avoiding failures in service, by extending the useful life of these items or by making faster operation possible so that less equipment may be used to perform the required operations. To illustrate these savings, some specific examples can be cited taken from the experiences at Bell Telephone Laboratories in research and development activities. A good illustration of the savings in engineering manpower is the case of the development engineer working on a new and complex mechanism. Without high-speed photography, it might be necessary to build a series of mechanisms and to test all of them for performance and life, a very expensive proposition both in material and in engineering manhours. From the experience gained with such a large variety of designs, it would then be possible to select one particular design for application. In contrast, the more modern practice of using high-speed photography enables the engineer, sometimes from a single model or parts of a model, to determine by measurement whether 366 November 1952 Journal of the SMPTE Vol. 59