Person: Ferrel, William
William Ferrel was an American astronomer who worked on the theory of tides.
Mathematical Profile (Excerpt):
- An event which heightened Ferrel's scientific interests and encouraged him to pursue his education further was the partial eclipse of the sun which he witnessed in 1832.
- In 1837 Ferrel was twenty-two years old and by that time he had saved enough money from his wages as a school teacher to allow him to finance his studies at college.
- (In 1853 the College merged to become the present day Franklin and Marshall College.) Ferrel studied at Marshall College for two years but by that time his savings were exhausted and he had to return to school teaching to make enough money to allow him to complete his studies.
- He entered Bethany College in 1842; it had been founded two years earlier in the Greater Wheeling area of West Virginia, so it had not been open when Ferrel began his studies for the first time.
- After graduation Ferrel returned to school teaching but not to his home, rather he taught in Liberty in western Missouri from 1844 to 1850 and then in Allensville in Todd County, Kentucky, from 1850 to 1854.
- It was while he was in Liberty around 1850 that Ferrel came across the a copy of Newton's Principia which had been ordered by a resident of Liberty but then never collected.
- Ferrel studied this work and began to form his own theories about tides.
- This conclusion contradicted that which Laplace had come to and Ferrel decided that Laplace had made an error in neglecting second order terms.
- The theories that Ferrel put forward became his first scientific paper which was written at the age of 36 in 1853.
- The year after this first paper appeared in Benjamin Gould's Astronomical Journal, Ferrel moved to Nashville Tennessee where he set up his own school.
- One particular friend was William Bowling who was a physician.
- In 1856 Ferrel published An essay on the winds and currents of the ocean in the Nashville Journal.
- His theory involved what is now known as a Ferrel cell in which air flows towards the pole and eastward near the earth's surface and towards the equator and westward at higher altitudes.
- Despite being an important step forward, Ferrel's theory does not match up with precisely what happens in practice although it was the first theory to explain the westerly winds in the middle latitudes of both the northern and southern hemispheres.
- In 1857 Ferrel was offered a position on the staff of The American Ephemeris and Nautical Almanac.
- It was not a post which he had applied for, indeed Ferrel never applied for any of the scientific positions which he held, but it was offered to him through Benjamin Gould who knew of Ferrel's abilities because of several papers which he had published by this time in the Astronomical Journal.
- Ferrel visited the staff of The American Ephemeris and Nautical Almanac in Cambridge, Massachusetts in the spring of 1857, was given certain work to undertake, then returned to his school in Nashville where he worked for another year.
- In the spring of 1858 his school was taken over by his partner and Ferrel moved to take up his new post.
- This law is now sometimes called Buys Ballot's law after the Dutch meteorologist Christoph H D Buys Ballot who gave the law independently of Ferrel but later acknowledged Ferrel's priority.
- From 1858 until 1867 Ferrel was a resident of Cambridge, Massachusetts while he worked for The American Ephemeris and Nautical Almanac.
- However he was now close to Harvard University and he made use of its library and discussed his ideas with the mathematicians there such as Benjamin Peirce, Simon Newcomb, Asaph Hall, and J D Runkle who was the editor of the American Mathematical Monthly in which Ferrel published a number of important articles.
- Benjamin Peirce later joined the United States Coast and Geodetic Survey and he persuaded Ferrel to join him.
- Ferrel went to Washington to take up this new post on 1 July1867.
- We have seen above how Ferrel's early work on tides sought to correct some problems which were in Laplace's treatment.
- Ferrel became the first to treat the non-linear case successfully.
- As well as research on tides Ferrel studied currents and storms, used tidal data to determine the mass of the moon, and he invented a machine to predict tidal maxima and minima.
- A decision was taken quickly to construct the tide predicting machine according to Ferrel's specification but it required a high quality machinist to undertake the work and it was eighteen months later before such a person could be found.
- With the construction still underway, Ferrel approached the Superintendent of the Coastal Survey on 9 August 1882 to offer his resignation so that he could take up a post with the United States Army Signal Service.
- The Superintendent asked Ferrel if he would continue to supervise the work of construction of his tide predicting machine after leaving the employment of the Coast and Geodetic Survey and of course he agreed.
- After working for four years Ferrel retired at the age of seventy.
Born 29 January 1817, Bedford (now Fulton) County, Pennsylvania, USA. Died 18 September 1891, Martinsburg, West Virginia, USA.
View full biography at MacTutor
Tags relevant for this person:
Astronomy, Origin Usa
Adapted from other CC BY-SA 4.0 Sources:
- O’Connor, John J; Robertson, Edmund F: MacTutor History of Mathematics Archive