Catalogue Entry: THEM00067

Proposals concerning calendar reform

Author: Isaac Newton

Source: Yahuda Ms. 24, National Library of Israel, Jerusalem, Israel

Custodial History

Bought at the Sotheby sale by Gabriel Wells for £54. Keynes asked to see it on 3 August 1936 but early in September he was informed that it had already been sold. On 4 November 1936 he asked Yahuda whether he had the lot and a week later Yahuda confirmed that he had. On 1 December Yahuda told him that he was sending him, as part of their exchange negotiations, lots 50 (now Keynes Ms. 35), 72 (now Keynes Ms. 44), 87 (now in the Boston Medical Library) and 222 (this manuscript), though in the event it would seem Keynes only kept the first two. See Spargo, '1936 sale', 130-32, where this manuscript is mistakenly referred to as SL225.

Sotheby Lot



A) 'Considerations about rectifying the Iulian Kalendar'. Two drafts and a fair copy, 10 pp. on 6 ff.; ff. 2v-2r (in that order) include part of an unrelated chemical text in Latin. On the deficiencies of both the Julian and the Gregorian calendars, with a proposed alternative to both.

B) 'The use of ye Kalendar for finding the Lords day and the moveable Feasts': draft table and method for determining these dates in the proposed new calendar, on the wrapper of a letter to Lord Chief Justice Greby, 1 f.

C) Variant set of proposals for rectifying the Julian calendar, with a table collating a year by the Julian calendar with Newton's proposed revision, and various calculations, 2 ff.

Calculations and rough drafts relating to the proposed revision, 1 f.

Notes about feast days in the early Church, 2 ff.; on the last page some statistics apparently relating to the French navy.

D) Various related calculations, a table entitled 'Observationes Hipparchi', and two drafts of a memorandum on the advantages of Newton's proposed calendar; 4 ff. of which 1 blank.

E) Draft and fair copy: 'Regulæ pro determinatione Paschæ [in the fair copy 'Paschatis']', 4 ff. The fair copy is in another hand.

F) Two variant drafts of a letter [apparently to the Bishop of Worcester] on calendar reform, in English, 4 ff. of which one blank. The text is interspersed with draft passages about Jewish chronology and Ezekiel's temple, and on f. 1v there is a note about Mint salaries and expenses.

G) Draft of a letter concerning 'the Paper, which his Lordp the Bp of Worcester [Edward Stillingfleet] sent to Dr Prideaux' (about ancient calendars), and Latin and English notes on Jewish chronology and the Temple of Zerubbabel, appended to the beginning of a draft letter addressed 'Reverendissimo Viro D. P. Allix S.T.D.' (i.e. Pierre Allix, with whom Newton corresponded in 1713), 2 ff.

Two wrappers, one with the heading in Thomas Pellet's hand: 'No 3 Considerations about the Iulian Calendar'.

See Brewster (1855), 2: 311-12 for discussion of the contents and dating of these documents

© 2024 The Newton Project

Professor Rob Iliffe
Director, AHRC Newton Papers Project

Scott Mandelbrote,
Fellow & Perne librarian, Peterhouse, Cambridge

Faculty of History, George Street, Oxford, OX1 2RL -

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