Hugh Longbourne Callendar

Birth & education

Callendar was born in Hatherop, Gloucestershire, the eldest son of the Reverend Hugh Callendar and Anne Cecilia Longbourne. He was christened in his father's church on May 24, 1863. After his father's death in 1867, he developed skills in languages and mathematics with a private tutor, building devices and teaching himself Morse code by age 10. At 11, he entered Marlborough College, participating in football, shooting, and gymnastics.

He began at Trinity College, Cambridge in 1882, earning first class honors in Classics in 1884 and graduating as 16th wrangler in mathematics in 1885. He then studied experimental physics at the Cavendish Laboratory under J.J. Thomson, developing a thesis on platinum thermometry and becoming a Fellow of Trinity in 1886. At Cambridge, he invented a shorthand system that Thomson learned and used.

Family and personal life

Callendar married Victoria Mary Stewart, whom he met at Cambridge, in 1894 in England. They had a daughter, Cecil (1895), and three sons: Guy Stewart Callendar (1898), Leslie Hugh (1896), and Maxwell Victor (1905). Guy Stewart proposed the effect of carbon dioxide emissions on the climate, known as 'The Callendar Effect'. One of Callendar's interests was motoring.

He undertook research on internal combustion engines, purchased a motorcycle in 1902 which he modified and improved himself, and in 1904 purchased and modified a car for family travels around England. His other interests included astronomy, nature study, competitive shooting, gymnastics, soccer, tennis, and handicraft, including automotive mechanics. He published a number of works on what he called 'Cursive Shorthand' and wrote on English spelling reform.

Career

At Cavendish Laboratory, Thomson advised Callendar to study metallic resistance thermometry. Werner von Siemens had first proposed a platinum resistance temperature detector in 1860, but his instrument readings were unstable. Callendar developed an equation for the resistance of metal as a function of temperature, accurate to within 1% from 0-600 °C. This equation was used to develop a standard scale of temperature, accepted by the Committee on Electrical Standards in 1899 for international use.

By 1886 he had developed a design for an accurate platinum resistance thermometer, correcting Siemens' errors. The thermometer measured temperatures with accuracy from -190 °C to 660 °C. J.J. Thomson praised it for providing a new tool that 'could determine temperatures with an ease and accuracy never obtainable before'. Callendar improved the heat range from -200 °C up to 1000 °C. His design underwent vigorous testing at the National Physical Laboratory, confirming its reliability.

The thermometer could measure the melting point of metals, aiding metal alloying, and was produced commercially by the Cambridge Instrument Company. Modern platinum thermometers are based on his model, with continual improvements in purity and size. His work led to the development of the rolling-chart thermometer for measuring climatic temperature over time. Platinum resistance thermometers continue to be used, primarily as calibrating devices due to their high accuracy and stability.

Birth & education

Callendar was born in Hatherop, Gloucestershire, the eldest son of the Reverend Hugh Callendar, a local Anglican rector, and Anne Cecilia Longbourne. He was christened in his father's church on May 24, 1863. His father died in 1867. From a young age, with a private tutor, he developed skills in languages and mathematics, built devices such as induction coils and generators, and taught himself Morse code by age 10.

At age 11, he began at Marlborough College, where he participated in football and represented the college in shooting and gymnastics. He started at Trinity College, Cambridge in 1882, earned first class honors in Classics in 1884, and graduated as the 16th wrangler with first class honors in mathematics in 1885. In 1885 he began studying experimental physics at the Cavendish Laboratory under physicist J.J. Thomson, with no practical experience or knowledge of physics.

There he developed his thesis on platinum thermometry and in 1886 became a Fellow of Trinity. While at Cambridge, he invented a new system of shorthand for writing quickly, which J.J. Thomson learnt and used.