John Somer 1340 -1410

Friar John Somer ca. 1340 -1410

A Franciscan Friar

John Somer was a contemporary of Geoffrey Chaucer (ca. 1340 -1400). He was probably born in the 1340s and the last record of his receiving a grant was 10 October 1409, so he probably died in that year.

Somer seems to have entered the order of the fratum minorum, Franciscan friars, in the friary at Bridgwater. There were Somers in Bridgwater who were of some standing and who leased or owned property in Friarn Street. John Somer is a witness to a document in 1307, but this must be perhaps our man’s father. John Somer appears in the Borough Archives in the 1330s and 1340s along with an Alice Somer (d 1352); perhaps his wife. Thomas Somer, co-executor of Alice’s will may be her son. Later archives tell of Margaret, daughter of John Somer, in Bridgwater in 1405. Another John Somer appear in the archives in 1374, 1376, and 1379, but is not given the style friar, so perhaps not the same man.

Our John Somer, the author of a Kalendarium and other works, might be related to this family, It is safe to assume that Fr. John Somer was in Oxford by 1380, when he wrote his kalendar ad meridiem Oxonie (for the meridian of Oxford). He was still a member of the Greyfriars convent in Oxford in 1394 and 1395, where he was recognised as an astronomer.

At Oxford, Somer would have had access to the Merton school of astronomy. He would have found instruction and resources to stimulate his scientific investigations and resulted in the production of his Kalendarium. Chaucer, in his Treatise on the Astrolabe, makes reference to the kalendar of the “reverent clerk Frere J Somer”.

By 1380, Somer had established a reputation as an astronomer . The Kalendarium was produced for Joan of Kent, the Princess of Wales, and mother of Richard II. The Princess died in 1399, and he then received a royal grant from the new king, Henry IV. He continued writing astronomical and astrological treatises and updating the charts accompanying the kalendar thorough the 1390s. His reputation as an astronomer survived well into the fifteenth century and the horoscope figure and a copy of Tabula Planetarum where still being ascribed to him in the sixteenth century.

The Kalendarium is in four parts: a prologue, including instructions for use of the tables; the monthly kalendar; additional tables containing Zodiac Man and explanatory text; and eclipse tables. 43 manuscripts containing the kalendarium or parts of it survive.

Somer wrote a Chronicle, identified in a manuscript in the British Library Chronica quedam brevis fratris Johannis Somour ordinis S Francisci de conventue ville Briggewater. In this, are listed every year from AD 1001 to 1532 and tabulated are the historical, religious, astronomical and political entries, probably in Somer’s own hand between 1348 until 1402, when a great thunderstorm was noted in Taunton, and the Walsingham comet noted in the same year. Probably after Somer’s death, the Chronicle records the laying of the foundation stone of the new church of the friars minor at Bridgwater between 9 and 10 o’clock in the morning of 4th March 1411.

It seem that John Somer was one of the leading , if not the leading, astrologer of his day. William Worcestre said he met a old man in 1478, Fr. John Wells, in Bridgwater then a tanner, who said he had been servant to John Somer.

John Somer left 40 marks for the library at the Bridgwater friary, and 200 marks for the new friary church .

Other works attributed to Somer are

Of Ille Days of the Yere (Days to be avoided in the year)

Canones pro veris motibus habendis planetarum : a perpetual calendar

Regule ad sciendum nati vitam secundum Johannem Somer ordinis minorum

Tabula medii motus solis in singulis 24 horis

Tabula proportionis diversitatis aspectus

Verus Motus Ultimo Decembri 1393 completus

A figure for casting a horoscope (in the Corpus Christi Library, Cambridge).


Mooney, L R, ed The Kalendarium of John Somer, The Chaucer Library, Athens: University of Georgia, 1998

Catto, J and Mooney, L R, The Chronicle of John Somer, Camden Miscellany XXXIV, 5th series Volume 10, 1997, pp201-285

Dilks, T B, Bridgwater Borough Archives, Somerset Record Society, 1933, 48.


An article on almanacs

A version of the kalendarium copied about 1417

Dictionary of National Biography

Dr Peter E Cattermole 31 January 2011