Richard Dunthorne

Richard Dunthorne (1711--March 3, 1775) was an English amateur astronomer. Dunthorne was born in Ramsey, Cambridgeshire. He worked as head of a university preparation school in Coggeshall, Essex. He subsequently had a "butlership" at Pembroke College, Cambridge.

Dunthorne planned and funded the construction of an observatory in 1765. The observatory was to be situated on the Shrewsbury Gate of St. John's College. Dunthorne donated the astronomical instruments himself. He performed observations of the transits of Venus in 1761 and 1769. He also published tables on the motion of Jupiter's satellites in 1762.

Dunthorne studied the phenomenon of the speed of the Moon's orbit. The change in the Earth's rotational period was measured at the time using eclipses. The timing of the eclipses over the centuries seemed to indicate that the Moon was accelerating in its orbit, when in fact what was actually happening was that the Earth's rotation was slowing down. Dunthorne similarly reported that ancient accounts of eclipses indicated that the Moon was speeding up in its orbit –an acceleration of about 0.00001 mph over a century.

He published papers in the "Philosophical Transactions", including "On the motion of the Moon" (1747), "On the acceleration of the Moon" (1749), and the letter "Concerning comets" in 1751.

Dunthorne also published a book of astronomical tables in 1739 called "Practical Astronomy of the Moon: or, new Tables... Exactly constructed from Sir Isaac Newton's Theory, as published by Dr Gregory in his Astronomy, London & Oxford, 1739". Dunthorne modeled his new tables on Isaac Newton's lunar theory of 1702 in order to test Newton's theories.

In a 1749 letter to the keeper of Cambridge's Woodwardian Museum, Dunthorne wrote: "After I had compared a good Number of modern Observations made in different Situations of the Moon and of her Orbit in respect of the Sun, with the Newtonian Theory...I proceeded to examine the mean Motion of the Moon, of her Apogee, and Nodes, to see whether they were well represented by the Tables for any considerable Number of Years..."ref|dunthorne1 A contemporary wrote of Dunthorne that "without the benefit of an Academical education he arrived at such a perfection in many branches of learning, and particularly in Astronomy, as would do honour to the proudest Professor in any University...he joined to a consummate excellence in his profession a generosity without limit in the exercise of it." [http://www.hps.cam.ac.uk/whipple/within.html]

Dunthorne died at Cambridge. Dunthorne crater, on the Moon, is named after him.

Notes

# Richard Dunthorne, "A Letter from the Rev. Mr. Richard Dunthorne to the Reverend Mr. Richard Mason F. R. S. and Keeper of the Wood-Wardian Museum at Cambridge, concerning the Acceleration of the Moon," "Philosophical Transactions (1683-1775)", Vol. 46, 1749 - 1750 (1749 - 1750), pp. 162-172.

ources

* [http://www.hps.cam.ac.uk/whipple/within.html Whipple Museum]
* [http://www.plicht.de/chris/files/d.htm#Dunthorne_Richard Christof A. Plicht, "R. Dunthorne," Red Hill Observatory]
* [http://www.ucl.ac.uk/sts/nk/newtry.htm Newton's 1702 Lunar Theory]
* [http://curious.astro.cornell.edu/question.php?number=124 Curious About Astronomy]
* [http://www.fortunecity.com/emachines/e11/86/rightans.html# “Right” Answers]