Canadian Inventions – The Quartz Clock

The telecommunications revolution that occurred at the turn of the 20th Century was invariably accompanied by new technologies created to support the burgeoning industry sector. Practical, commercial telephone and radio networks required greater precision than had been necessary in the laboratory, and the inadequacies of technological infrastructure were becoming increasingly evident. One particular deficiency was the lack of an accurate frequency reference to allow the various networks to be calibrated precisely. In 1925, Warren Marrison, a 29-year-old engineer at Bell Laboratories in New York, began work on a new frequency reference. Marrison was a radio enthusiast. He had been the first graduate of the new engineering physics program at Queen’s University in Kingston, Ontario (near his birthplace in Frontenac County) and had served as a radio communications engineer with the Royal Flying Corps during the World War I. Intrigued by the recent success his colleagues had experienced with crystal oscillators, Marrison believed that he could create an accurate frequency reference from the oscillating vibrations of a quartz crystal. Marrison soon developed a prototype frequency reference based on the piezoelectric behaviour (a defined relationship between the mechanical state and electrical state) of a refined quartz crystal. The crystal was excited by an alternating electric field and the induced vibrations transformed into an oscillating signal by vacuum tube electronics. The prototype was cumbersome, occupying a small room in the laboratory, but seemed to provide an accurate frequency reference signal. Marrison wanted to accurately determine the frequency of the reference signal, but the oscillating frequency of the crystal was too high to be displayed by existing electronics. After several attempts, he was able to successfully divide the reference signal frequency and drive a synchronous motor to display the accumulated vibrations. Although his intention had been to quantify the oscillating frequency of the reference signal, Marrison had inadvertently also created the first quartz clock. After confirming the accuracy of the time signal generated by the oscillating crystal, Marrison set about improving his prototype, now with the intention of creating a time-standard clock. Over the next decade quartz oscillators were adopted in place of mechanical escapements in precision laboratory time standards throughout the world. The greater accuracy of the quartz oscillator allowed scientists to detect irregularities in the earth’s rotation that would eventually lead to a new definition of time (based on atomic half-life instead of on the earth’s rotation). However, the general public had to wait until the arrival of digital logic in the 1960s before the quartz timepiece became widely available. Marrison continued to work as a telecommunications engineer, despite being recognised by many leading horology institutions. He received numerous patents for his work with quartz oscillators and was granted over 70 patents during his life. Summary by: Richard Murphy