Jacob Clay () (January 18, 1882–December 31, 1955) was a prominent

Dutch Dutch commonly refers to: * Something of, from, or related to the Netherlands * Dutch people () * Dutch language () Dutch may also refer to: Places * Dutch, West Virginia, a community in the United States * Pennsylvania Dutch Country People E ...

physicist who first suggested and provided evidence that

cosmic rays Cosmic rays 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 System in our ow ...

are charged particles.

Early life

Clay was born "Jacob Claij" in

Berkhout Berkhout is a village in the northwest Netherlands. It is in the municipality of Koggenland, North Holland, about west of Hoorn. History The village was first mentioned around 1312 as Berchout, and means "deciduous forest of birch (''Betula ...

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''; nl, Universiteit Leiden) is a public research university in Leiden, Netherlands. The university was founded as a Protestant university in 1575 by William, Prince of Orange, as a reward to the city of Le ...

under

Heike Kamerlingh Onnes Heike Kamerlingh Onnes (21 September 1853 – 21 February 1926) was a Dutch physicist and Nobel laureate. He exploited the Hampson–Linde cycle to investigate how materials behave when cooled to nearly absolute zero and later to liquefy heliu ...

and

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

. After obtaining his Ph.D. degree in 1908 he married

Tettje Clay-Jolles Tettje Clay-Jolles (1881–1972) was one of the first female Dutch physicists. She studied the variation of atmospheric radiation with geographic latitude. Early life Clay-Jolles was born in 1881 in Assen, Netherlands to Eva Dina Halbertsma and ...

with whom he had a son.

Career

After teaching in Leiden and at the Technische Hogeschool in Delft from 1906 to 1920, he was appointed Professor at the newly founded

Bandung Institute of Technology The Bandung Institute of Technology ( id, Institut Teknologi Bandung, abbreviated as ITB) is a national research university located in Bandung, Indonesia. Since its establishment in 1920, ITB has been consistently recognized as Indonesia's premi ...

. Clay collaborated with his wife

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, nl, Universiteit van Amsterdam) is a public research university located in Amsterdam, Netherlands. The UvA is one of two large, publicly funded research universities in the city, the other being ...

, 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 municipality and town in the province of Utrecht, Netherlands. It had a population of in . De Bilt houses the headquarters of the Royal Netherlands Meteorological Institute (KNMI). It is the ancestral home and namesake for the pro ...

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, 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 University of Amsterdam faculty Bandung Institute of Technology faculty Members of the Royal Netherlands Academy of Arts and Sciences Fellows of the American Physical Society