John Michell

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Torsion balance in the
Cavendish experiment
Simulation: A galaxy passes behind a black hole. The deflection of the light and the own darkness of the "star" also expected Michell.
Animation of an eclipsing double star with resulting light curve

John Michell (born December 25, 1724 , † April 29, 1793 in Thornhill , Yorkshire ) was an English natural philosopher and geologist.

life and work

Michell 1762 Woodwardian Professor of Geology at Queens' College of Cambridge University . In 1760 he was appointed a member of the Royal Society of London .

Michell constructed a torsion balance to measure the force of gravity for the first time , but did not carry out the relevant investigations. However, after his death in 1797, Henry Cavendish successfully used his device to determine the gravitational constant . In his report to the Royal Society, Cavendish expressly refers to Michell's merits.

Michell is also considered a co-founder of seismology . In 1760 he attributed earthquakes to undulations in the earth. He suspected a connection between earthquakes and volcanism.

Based on the then prevailing corpuscle theory of light, in 1783 he suspected the corresponding influence of gravity on light and also the existence of "dark stars", similar to black holes .

Also in 1783, the explanation with two different stars for the eclipsing Algol was first described in a letter from Michell to Cavendish.

Works

  • Observations on the Same Comet. In a Letter to Mr. James Short, FRS In: Philosophical Transactions of the Royal Society . Vol. 51, 1759/1760, pp. 466-467, doi: 10.1098 / rstl.1759.0044 .
  • A Recommendation of Hadley's Quadrant for Surveying, Especially the Surveying of Harbors, Together with a Particular Application of It in Some Cases of Pilotage. In: Philosophical Transactions of the Royal Society. Vol. 55, 1765, pp. 70-78, doi: 10.1098 / rstl.1765.0010 .
  • Proposal of a Method for Measuring Degrees of Longitude upon Parallels of the Equator. In: Philosophical Transactions of the Royal Society. Vol. 56, 1766, pp. 119-125, doi: 10.1098 / rstl.1766.0016 .
  • An Inquiry into the Probable Parallax, and Magnitude of the Fixed Stars, from the Quantity of Light Which They Afford us, and the Particular Circumstances of Their Situation. In: Philosophical Transactions of the Royal Society. Vol. 57, 1767, pp. 234-264, doi: 10.1098 / rstl.1767.0028 .
  • On the Means of Discovering the Distance, Magnitude, & c. of the Fixed Stars, in Consequence of the Diminution of the Velocity of Their Light, in Case Such a Diminution Should be Found to Take Place in any of Them, and Such Other Data Should be Procured from Observations, as Would be Farther Necessary for That Purpose. In a letter to Henry Cavendish, Esq. FRS and AS In: Philosophical Transactions of the Royal Society. Vol. 74, 1784, pp. 35-57, doi: 10.1098 / rstl.1784.0008 .

literature

Web links

Individual evidence

  1. ↑ Russell McCormmach: Weighing the World: The Reverend John Michell of Thornhill. Verlag Springer Science & Business Media, 2011, p. 360 middle
personal data
SURNAME Michell, John
BRIEF DESCRIPTION English natural philosopher and geologist
DATE OF BIRTH December 25, 1724
DATE OF DEATH April 29, 1793
Place of death Thornhill , Yorkshire