Warren Perry Mason (September 28, 1900 – August 23, 1986) was an American electrical engineer and physicist at Bell Labs. A graduate of Columbia University, he had a prolific output, publishing four books and nearly a hundred papers. He was issued over two hundred patents, more than anyone else at Bell Labs. His work included acoustics, filters, crystals and ceramics, materials science, polymer chemistry, ultrasonics, bonding to semiconductors, internal friction, and viscoelasticity. Mason founded the field of distributed-element circuits. He was the first to experimentally show viscoelasticity in individual molecules. He found experimental evidence of electron-phonon coupling in solids and made measurements that aided the theories of phonon drag and superconductivity. Many of Mason's inventions in electronics are still widely used by modern circuit designers.
Family and education Mason was born in Colorado Springs, Colorado, on September 28, 1900, to Kate Sagendorph Mason and Edward Luther Mason, a school principal and insurance salesman. Both his mother and father graduated from the University of Michigan around 1890. His father died when he was fifteen. His elder brother, Edward Sagendorph Mason, became a notable economist. Mason obtained a B.Sc. in electrical engineering from the University of Kansas in 1921. He continued his education part-time after this at Columbia University, obtaining an M.A. in 1924 and a Ph.D. in 1928, both in physics. Mason married Evelyn Stuart McNally in 1929. Evelyn was a graduate of Rutgers University and worked as a child psychologist in schools. They had a daughter, Penelope E. Mason. Evelyn died in 1953. Mason married his second wife, Edith Ewing Aylsworth, a teacher, in 1956. Mason and Edith were passengers in the 1965 Carmel mid-air collision. Their plane crash-landed near Danbury, Connecticut, where several people died, including the pilot, who re-entered the burning plane in an attempt to rescue a passenger. Edith died in 1985.
Career Mason joined the Western Electric Company in 1921. In 1925, Bell Telephone Laboratories (Bell Labs) was split off from Western Electric as a separate company. Mason went with Bell Labs and remained there for his entire career. He retired from Bell Labs in 1965 but remained a consultant there for a further two years. After retirement, he held a visiting professor post at Columbia University and was a research associate at Columbia's Henry Krumb School of Mines. Mason retired from Columbia in 1977. Mason was a founding member of the Acoustical Society of America, attending its first meeting in December 1928. He later became its president in 1956. Mason was amongst the first three fellows elected to the Society of Engineering Science in 1975 together with Ahmed Cemal Eringen and Harold Liebowitz. Mason died 23 August 23, 1986, in Gainesville, Florida.
Work Mason's work covered a wide range of fields. A large part of his work concerned filtering, not only in the electrical domain, but also in the mechanical and acoustic domains. Other fields of study included piezoelectric crystals and ceramics, ferroelectric crystals, underwater sound transducers, bonding of metals to metals and semiconductors, physics of wear, semiconductor strain gauges, metal fatigue, and internal friction of solids and liquids.
Radio-frequency engineering Mason worked on mechanical filters, a key component of frequency-division multiplexing in telephone carrier systems. They can be made with much sharper transition bands than can be achieved with conventional LC filters. Mason invented a new type of mechanical filter, the quartz crystal filter consisting of lattices of crystals, which became the standard form of filtering on these systems. Mason showed that the efficiency and bandwidth of acoustic transducers, such as those used in sonar, could be massively improved through mechanical–electrical analogies and applying electrical network theory, in particular filter theory.
Acoustic and electrical filters
Mason's doctoral thesis was on acoustic filters and horns. In this work, Mason pioneered the use of the distributed-element model to describe acoustic filters. He later extended this work for distributed electrical filters and distributed mechanical filters, making him the founder of the field of distributed-element circuits.
Piezoelectric crystals Mason was head of the Crystal Research Department 1935–1948, which studied piezoelectric crystals. He invented the GT crystal cut which has a near zero temperature coefficient of its resonant frequency. The crystal is widely used where accurate frequency is required such as in frequency standards and filtering. Other materials studied were ammonium dihydrogen phosphate, used in sonar transducers, barium titanate, an electrostrictive material, and ethylene diamine tartrate. The latter material was studied as a possible solution to the shortage of Brazilian quartz, since it was water-soluble and hence growable in the laboratory. However, it became unnecessary once quartz crystal growing was possible.
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