Research And Dr. Langmuir

Authors: Laurence Ashley Hawkins

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August 1955 | Volume 6, Issue 5

Text Complexity Grade Level

Mr. Hawkins, who was born in Pittsfield, Massachusetts, in 1877, went to the General Electric Company in 1903 and was executive engineer of its research laboratory from 1912 to 1945. The following passages comment interestingly on some of the scientists whose work helped to make radio possible.

The term “research” has been used to cover a multitude of activities but in General Electric it has a very special significance. Research is not testing, it’s not development, it’s not measurement, it is exploration of the unknown. The research man deals with unknown things, the engineer deals with things that are known.

Dr. Irving Langmuir, who came to Schenectady in 1909 and later became associate director of the laboratory, tells of his initial experience in the laboratory when he asked Dr. Whitney, the director, what he had better do. Dr. Whitney told him to look around the laboratory to see if he found anything that interested him. He did so and became interested first in the darkening of the bulbs of the tungsten filament lamps, the result of Coolidge’s work, which were on light tests in considerable number in the laboratory. Langmuir always wanted to know the reason why, so he started a study of the blackening. He had no definite improvement in mind, he wasn’t looking for a better lamp, he simply was curious as to why it was that this gradual darkening took place.

He found out why, and his studies resulted in the invention of the gas-filled lamp which is the universal incandescent lamp of today except in the very smallest sizes. It also led to the invention of atomic hydrogen welding, and later some of his work became directly applicable to the studies he made on electron tubes, which were a large element in laying the foundation for broadcasting.

Langmuir’s initial contribution to radio came about this way. An engineer, Dr. E. F. W. Alexanderson, who already had established a world-wide reputation for his contributions to radio—among others the high frequency alternator—came to Langmuir to find out why the De Forest audion which was used in radio reception couldn’t be made to handle real power and so act as an amplifier and transmitter for radio telephony.

The De Forest audion, which had its genesis in an old experiment of Edison’s in which he discovered what is known as the Edison effect, was essentially what is called in X-ray parlance, a soft tube. That is, it had an appreciable amount of residual gas left in it and if the vacuum were made too good, the tube refused to work. The current belief at the time of Alexanderson’s visit to Langmuir was that the residual gas had something to do with the emission of electrons from the hot filament. But Langmuir made this study and found that that was not so, that electrons came out from the hot filament just as freely in the

highest possible vacuum as when there was some residual gas. The reason for the audion’s stopping to function if the vacuum became too good was that in high vacuum, the first electrons coming out from a filament, being negative charges, built up a negative field around the filament and repelled other electrons that were trying to leave the filament. Langmuir showed that by bringing the elements of the tube very close together and using a high voltage so as to pull the electrons quickly across the space, he could build a tube which would operate at the highest obtainable vacuum and which meant that high voltage could be used and consequently the tube could carry real power. In other words, that was the way that Langmuir invented the radio power tube which is the heart of the broadcasting station today.

I think the first tube which Langmuir built operated with something like 3,000 volts, but the current that the tube would carry was carried progressively to higher and higher values. It was Langmuir’s work which made it possible for the research laboratory to supply to Army and Navy and Coast Guard all the transmitting tubes that were used in World War I for radio telephony.

The work which Langmuir did in developing the high-vacuum power tube, was paralleled by Arnold in the Bell Telephone laboratories. There has always been some question as to the priority between the two.

Before the United States entered World War I, all the elements for not only radio telephony, but also for radio broadcasting had been developed. The only essential difference between the transmitter for telephony as used in that war and for broadcasting as used today was in the amount of power. That development meant nothing more than producing higher powered tubes, which was a simple development after Langmuir’s fundamental work.

It was not until a year or two after the Armistice that the idea of broadcasting, which was due to Conrad of the Westinghouse Company, came into being. Then immediately the broadcasting industry started a very rapid growth.

Research And Dr. Langmuir (August 1955 | Volume: 6, Issue: 5)

Research And Dr. Langmuir

Text Complexity Grade Level