Jacob Clay () (January 18, 1882–December 31, 1955) was a prominent Dutch physicist who first suggested and provided evidence that

cosmic rays Cosmic rays or astroparticles are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light. They originate from the Sun, from outside of the Solar ...

are charged particles.

Early life

Clay was born "Jacob Claij" in Berkhout on 18 January 1882 as the son of Pieter Claij and Neeltje Molenaar. After attending the Erasmiaans Gymnasium, he studied physics at the

University of Leiden Leiden University (abbreviated as ''LEI''; ) is a public research university in Leiden, Netherlands. Established in 1575 by William, Prince of Orange as a Protestant institution, it holds the distinction of being the oldest university in the Neth ...

under Heike Kamerlingh Onnes and

Hendrik Antoon Lorentz Hendrik Antoon Lorentz ( ; ; 18 July 1853 – 4 February 1928) was a Dutch theoretical physicist who shared the 1902 Nobel Prize in Physics with Pieter Zeeman for their discovery and theoretical explanation of the Zeeman effect. He derived ...

. After obtaining his Ph.D. degree in 1908 he married Tettje Clay-Jolles with whom he had a son.

Career

After teaching in Leiden and at the Technische Hogeschool in

Delft Delft () is a List of cities in the Netherlands by province, city and Municipalities of the Netherlands, municipality in the Provinces of the Netherlands, province of South Holland, Netherlands. It is located between Rotterdam, to the southeast, ...

from 1906 to 1920, he was appointed Professor at the newly founded

Bandung Institute of Technology The Bandung Institute of Technology (; , abbreviated as ITB) is a public research university located in Bandung, Indonesia. It has produced many notable leaders in science, engineering, politics, business, academia, and culture. ITB is one of th ...

. Clay collaborated with his wife Tettje Clay-Jolles on research which discovered that atmospheric radiation varies according to geographic latitude. On a trip back to the Netherlands he measured the cosmic radiation and noticed an increase the further he was from the equator, which suggested to him that cosmic rays are deflected by the geomagnetic field and let him to propose that they are charged particles rather than photons. This proposal was generally accepted by 1932. In 1929 he became professor at the

University of Amsterdam The University of Amsterdam (abbreviated as UvA, ) is a public university, public research university located in Amsterdam, Netherlands. Established in 1632 by municipal authorities, it is the fourth-oldest academic institution in the Netherlan ...

, publishing over 200 papers until his retirement in 1952. In 1928 he became correspondent of the Royal Netherlands Academy of Arts and Sciences, he resigned a year later. In 1936 he became a full member. Clay died on 31 December 1955 in

De Bilt De Bilt () is a Municipalities of the Netherlands, municipality and town in the Provinces of the Netherlands, province of Utrecht (province), Utrecht, Netherlands. It had a population of in . De Bilt houses the headquarters of the Royal Netherland ...

Personal life

Clay met and fell in love with Tettje Jolles, a fellow PhD student, and in 1908 the two were married. They had three children. In 1920, the family moved to

Bandung Bandung is the capital city of the West Java province of Indonesia. Located on the island of Java, the city is the List of Indonesian cities by population, fourth-most populous city and fourth largest city in Indonesia after Jakarta, Surabay ...

, Java when Jacob Clay was hired as a professor of physics at the Institute of Technology.

References

* H.F.Jongen
Claij, Jacob (1882-1955)
in Biografisch Woordenboek van Nederland. 2-11-2013 {{DEFAULTSORT:Clay, Jacob 1882 births 1955 deaths People from Koggenland 20th-century Dutch physicists 20th-century Dutch philosophers Leiden University alumni Academic staff of the University of Amsterdam Academic staff of Bandung Institute of Technology Members of the Royal Netherlands Academy of Arts and Sciences Fellows of the American Physical Society