Milestone-Proposal:Walter Guyton Cady

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Docket #:2017-11

This Proposal has been approved, and is now a Milestone

To the proposer’s knowledge, is this achievement subject to litigation? No

Is the achievement you are proposing more than 25 years old? Yes

Is the achievement you are proposing within IEEE’s designated fields as defined by IEEE Bylaw I-104.11, namely: Engineering, Computer Sciences and Information Technology, Physical Sciences, Biological and Medical Sciences, Mathematics, Technical Communications, Education, Management, and Law and Policy. Yes

Did the achievement provide a meaningful benefit for humanity? Yes

Was it of at least regional importance? Yes

Has an IEEE Organizational Unit agreed to pay for the milestone plaque(s)? Yes

Has the IEEE Section(s) in which the plaque(s) will be located agreed to arrange the dedication ceremony? Yes

Has the IEEE Section in which the milestone is located agreed to take responsibility for the plaque after it is dedicated? Yes

Has the owner of the site agreed to have it designated as an IEEE Milestone? Yes

Year or range of years in which the achievement occurred:


Title of the proposed milestone:

Piezoelectric Quartz Oscillator, 1921-1923

Plaque citation summarizing the achievement and its significance:

In 1921, research at Wesleyan led to development of the first circuit to control frequencies based on a quartz crystal resonator. This technique was later applied in standards of frequency as a filter and for coupling between circuits. Piezoelectric quartz oscillators advanced ultrasonics, sonar, radar, and myriads of other electronic applications. They appeared in everyday life through their use in quartz wristwatches.

200-250 word abstract describing the significance of the technical achievement being proposed, the person(s) involved, historical context, humanitarian and social impact, as well as any possible controversies the advocate might need to review.

IEEE technical societies and technical councils within whose fields of interest the Milestone proposal resides.

In what IEEE section(s) does it reside?


IEEE Organizational Unit(s) which have agreed to sponsor the Milestone:

IEEE Organizational Unit(s) paying for milestone plaque(s):

Unit: UFFC
Senior Officer Name: Clark Nguyen

IEEE Organizational Unit(s) arranging the dedication ceremony:

Unit: UFFC
Senior Officer Name: Clark Nguyen

IEEE section(s) monitoring the plaque(s):

Milestone proposer(s):

Proposer name: Sidney Lang
Proposer email: Proposer's email masked to public

Please note: your email address and contact information will be masked on the website for privacy reasons. Only IEEE History Center Staff will be able to view the email address.

Street address(es) and GPS coordinates in decimal form of the intended milestone plaque site(s):

265 Church StreetMiddletown, Connecticut 06459, USA41.553366, -71.657601

Describe briefly the intended site(s) of the milestone plaque(s). The intended site(s) must have a direct connection with the achievement (e.g. where developed, invented, tested, demonstrated, installed, or operated, etc.). A museum where a device or example of the technology is displayed, or the university where the inventor studied, are not, in themselves, sufficient connection for a milestone plaque.

Please give the address(es) of the plaque site(s) (GPS coordinates if you have them). Also please give the details of the mounting, i.e. on the outside of the building, in the ground floor entrance hall, on a plinth on the grounds, etc. If visitors to the plaque site will need to go through security, or make an appointment, please give the contact information visitors will need. The site is the present Physics Department building. It is located within 300 meters of the site where Cady did his research.

Are the original buildings extant?

Yes. The buildings current use has been reconfigured for offices.

Details of the plaque mounting:

The plaque will be wall mounted in a meeting room that was dedicated to Cady on his 100th birthday, 10 December 1974

How is the site protected/secured, and in what ways is it accessible to the public?

The building is open 6 AM to 10 PM and the room is freely accessible any time that the building is open.

Who is the present owner of the site(s)?

Wesleyan University

What is the historical significance of the work (its technological, scientific, or social importance)? If personal names are included in citation, include justification here. (see section 6 of Milestone Guidelines)

Professor Walter Guyton Cady died on December 9, 1974, the day before his 100th birthday. Professor Cady, best known for his discovery of the principle of the crystal oscillator and his monumental treatise Piezoelectricity , well deserves the title of the "Father of Modern Piezoelectricity".

The piezoelectric effect was discovered by Jacques and Pierre Curie in 1880. They found that a pressure on certain faces of a quartz crystal produced electric charges and a voltage could be measured between the faces. This is the direct piezoelectric effect and it is exhibited by single crystals, ceramics, polymers, and biological materials that have no center of crystallographic symmetry. Twenty of the 21 non-centrosymmetric point groups show this effect. The Curie brothers had discovered the direct piezoelectric effect. In the converse piezoelectric effect, an electric field applied between certain surfaces of a piezoelectric material results in a strain, a change in dimensions of the material. It was predicted by Gabriel Lippmann in 1881 and was immediately confirmed experimentally by the Curies. The piezoelectric effect was only a scientific curiosity until 1917 when Paul Langevin showed that a device consisting of a mosaic of quartz crystals mounted between two steel plates and immersed in sea water could generate longitudinal waves and pick up reflections from objects some distance away.

Cady was born on December 10, 1874, in Providence, Rhode Island. He studied at Brown University, receiving the Ph:B. degree in 1895 and the M. A. degree in 1896. His master's thesis on the dynamic behavior of a top with a blunt tip was carried out under the direction of Carl Barus. During this time Cady published his first paper, on the determination of the volume of an air bulb thermometer. He continued his graduate studies at the University of Berlin receiving the Ph.D. degree in 1900. His thesis was a study of the energy of cathode rays, under the direction of Warburg and Walter Kaufmann.

Upon his return to the United States, Cady joined the U.S. Coast and Geodetic Survey and became the head of a magnetic observatory in Maryland. During this time he published his first completely independent work on a direct recording magnetic variometer. In 1902 he joined the Physics Department of Wesleyan University in Middletown, Connecticut. He rose to the rank of Assistant Professor the next year and became Professor and Head of the Physics Department in 1907. He remained at Wesleyan University until 1951, becoming Professor Emeritus in 1946. During his early years at Wesleyan he studied arc and glow discharges between metallic electrodes.

Professor Cady's interests in piezoelectricity were first aroused in 1917. The German submarine menace in World War I had reached very severe proportions. A conference sponsored by the National Research Council was convened in Washington on June 14-16, 1917 under the leadership of Robert A. Millikan to discuss the problem. Cady was invited to the conference because of his interests in submarine detection with ultrasonic waves produced by a magnetostrictive generator. At the conference, the French delegates announced that Paul Langevin had been generating and detecting ultrasonic waves under water by means of quartz-steel "sandwich" transducers. As a result of the meeting, Cady's research interests permanently turned to piezoelectricity. He first collaborated with a General Electric group studying quartz and Rochelle salt crystals in 1917 and then with a Columbia University group where he worked on Rochelle salt hydrophone receivers designed to resonate at the transmitted frequency. These studies culminated in field tests at the Navy Yard in Key West, Florida in 1918 and the Naval Station in New London, Connecticut in 1918-1919.

During the course of his tests in 1917 and 1918, Cady noticed the effect on the driving circuit of a quartz crystal when the frequency was close to the natural mode of vibration of the crystal. On February 26, 1921, Cady described a piezoelectric resonator at a meeting of the American Physical Society and suggested that it could be used as a standard of frequency or a coupling device between circuits. Immediately after, he began the investigation of the control of the frequency of an oscillator by means of a crystal. A description of the first piezo-oscillator circuit, using a 39-mrn long quartz bar oscillating in a longitudinal mode at about 70,000 Hz, was presented to the American Physical Society on December 28, 1921.

Cady took his only sabbatical leave from Wesleyan in 1923 to travel to Europe for an inter-comparison of quartz resonators, calibrated at the National Bureau of Standards, with frequency standards at the national laboratories of Italy, France, and England. During the next twenty years, Cady concentrated his efforts on the piezo-resonator and the piezo-oscillator as well as on fundamental piezoelectric studies, with special emphasis on Rochelle salt. In the early 1930's, Cady planned to write a short monograph on piezoelectricity. But upon a suggestion by F. K. Richtmyer, he extended it into a full-length book, the monumental Piezoelectricity , first published in 1946. The book was revised and republished in 1964, and, even today, is still so relevant that every researcher in the field makes use of it.

Cady's services were required for underwater detection problems again immediately after the attack on Pearl Harbor in World War II, and he spent a short period at the Naval and Sound Laboratory in San Diego in 1941. In 1945, he worked for the Radiation Laboratory in Cambridge, Massachusetts, on quartz transducers for radar trainers. After World War II and his official retirement, Cady remained at Wesleyan studying transducer theory, methods of measurement, and acoustic-radiation pressure with the support of the Office of Naval Research. He worked at the California Institute of Technology from 1951 to 1955 on problems of resonator and filter theory and measurement of acoustic power. In his 1955 experiments, he produced acoustic waves at a frequency of 3000 MHz. Cady continued an active life, publishing a mathematical paper on the circular tractrix in 1965 and receiving patents on a piezoelectric vibrator in 1968 and on a detector of mechanical vibrations in 1973. Professor Cady was active in a number of societies including the American Physical Society, the American Association for the Advancement of Science, the American Institute of Electrical Engineers, and the Institute of Radio Engineers of which he was president in 1932-1933. He was a member of several committees of the National Research Council and was a Lieutenant Commander in the U.S. Naval Reserve. Among the honors awarded him were the Liebmann Memorial Prize of the Institute of Radio Engineers in 1928 and the 1937 Duddell Medal of the Physical Society of London. He received honorary Sc.D. degrees from Brown University in 1938 and Wesleyan University in 1958.

Walter Guyton Cady wrote, "In experimental work I have learned the value of making a special study of obstacles, hindrances, and disturbing factors, to see if they can be made to serve a useful purpose. In other words, to convert stumbling blocks into stepping stones". Professor Cady's stepping stone of the piezo­ electric oscillator continues today to enter our laboratories and enrich our lives through devices as diverse as quartz thermometers, film-thickness gauges, piezoelectric chemical detectors, and quartz watches.

What obstacles (technical, political, geographic) needed to be overcome?

None are known

What features set this work apart from similar achievements?

Cady's accomplishments were unique. Nothing similar had ever been done previously.

Supporting texts and citations to establish the dates, location, and importance of the achievement: Minimum of five (5), but as many as needed to support the milestone, such as patents, contemporary newspaper articles, journal articles, or chapters in scholarly books. 'Scholarly' is defined as peer-reviewed, with references, and published. You must supply the texts or excerpts themselves, not just the references. At least one of the references must be from a scholarly book or journal article. All supporting materials must be in English, or accompanied by an English translation.

Supporting materials (supported formats: GIF, JPEG, PNG, PDF, DOC): All supporting materials must be in English, or if not in English, accompanied by an English translation. You must supply the texts or excerpts themselves, not just the references. For documents that are copyright-encumbered, or which you do not have rights to post, email the documents themselves to Please see the Milestone Program Guidelines for more information.

Documents will be sent separately as a zip file containing six files. The zip file will be e-mailed to

Please email a jpeg or PDF a letter in English, or with English translation, from the site owner(s) giving permission to place IEEE milestone plaque on the property, and a letter (or forwarded email) from the appropriate Section Chair supporting the Milestone application to with the subject line "Attention: Milestone Administrator." Note that there are multiple texts of the letter depending on whether an IEEE organizational unit other than the section will be paying for the plaque(s).

Please recommend reviewers by emailing their names and email addresses to Please include the docket number and brief title of your proposal in the subject line of all emails.