ELECTRICAL INDUSTRY — SMITH 201 



tion along transmission lines. Then came a quiet period of several 

 years in its development, followed about 1935 by an intensified ac- 

 tivity which shows no signs of any immediate slackening. The need 

 for high-speed relaying of long lines, the development of better tubes, 

 and other changes in the industry spurred engineers to adapt the 

 fundamentals of carrier current to relaying and supervision as well 

 as communication. 



Spot welding has been a practical, though limited, industrial tool 

 for many years. However, some 6 or 8 years ago, the idea was con- 

 ceived of using the ignitron * to control exactly the duration of the 

 welding current. Since that time, spot welding has grown enor- 

 mously both in total use and in diversity of applications. The ig- 

 nitron, incidentally, was originally developed not with welding in 

 mind but to increase the reliability of mercury-arc rectifiers. 



THE PROBLEM OF OBSOLESCENCE 



The industrial laboratory poses the inexorable problem of obsoles- 

 cence. Fortunately the leaders of the electrical industry have taken 

 the far-sighted view that, in order to make sound progress, the seem- 

 ing ruthlessness of obsolescence must be accepted. Unless one has 

 studied the rates of development and consequently the rates of obso- 

 lescence, it is seldom realized how relentless is the march of progress. 



A plant that is modern today may be out of date tomorrow. As 

 a matter of fact, the more progressive companies attempt to antici- 

 pate obsolescence. Capital expenditures are made on the basis of 

 the time at which the new plant or equipment will be obsolete, not 

 when it is worn out. 



The discovery of a new fact in science may completely upset an 

 existing design. Even though the style or performance of a product 

 may not be greatly modified, the practice of the art or process by 

 which it is produced may be radically changed. With the steep rise 

 of welding not long ago, in a few short years the method of con- 

 structing most large machines swung from casting to welded fabri- 

 cation. Neither the appearance nor the performance of the machines 

 was fundamentally altered by this change; the principal motive is 

 economy of time and of construction cost. 



It behooves all managements to keep themselves keenly alive to the 

 necessity of meeting changes resulting from progress. Of all com- 

 petition, there is none quite so ruthless as that which replaces. We 

 all can remember that during the early stages of radiobroadcasting, 

 several plants rapidly grew up for the making of radio headsets. 



♦The Ignitron is a special form of the mercury-arc rectifler, and is generally used to 

 convert alternating current to direct current. 



