It seems clear that the Eldar in Middle-earth, who had, as Samwise remarked, more time at their disposal, reckoned in long periods, and the Quenya word yén, often translated ‘year’ (p. 377), really means 144 of our years. The Eldar preferred to reckon in sixes and twelves as far as possible. A ‘day’ of the sun they called ré and reckoned from sunset to sunset. The yen contained 52,596 days. For ritual rather than practical purposes the Eldar observed a week or enquië of six days; and the yén contained 8,766 of these enquier, reckoned continuously throughout the period.
In Middle-earth the Eldar also observed a short period or solar year, called a coranar or ‘sun-round’ when considered more or less astronomically, but usually called loa ‘growth’ (especially in the north-western lands) when the seasonal changes in vegetation were primarily considered, as was usual with the Elves generally. The loa was broken up into periods that might be regarded either as long months or short seasons. These no doubt varied in different regions; but the Hobbits only provide information concerning the Calendar of Imladris. In that calendar there were six of these ‘seasons’, of which the Quenya names were tuilë, lairë, yávie, quelle, hrívë, coirë, which may be translated ‘spring, summer, autumn, fading, winter, stirring’. The Sindarin names were ethuil, laer, iavas, firith, rhîw, echuir. ‘Fading’ was also called lasse-lanta leaf-fall’, or in Sindarin narbeleth ‘sun-waning’.
Lairë and hrívë each contained 72 days, and the remainder 54 each. The loa began with yestarë, the day immediately before tuilë, and ended with mettarë, the day immediately after coirë. Between yavië and quelle were inserted three enderi or ‘middle-days’. This provided a year of 365 days which was supplemented by doubling the enderi (adding 3 days) in every twelfth year.
How any resulting inaccuracy was dealt with is uncertain. If the year was then of the same length as now, the yén would have been more than a day too long. That there was an inaccuracy is shown by a note in the Calendars of the Red Book to the effect that in the ‘Reckoning of Rivendell’ the last year of every third yén was shortened by three days: the doubling of the three enderi due in that year was omitted; ‘but that has not happened in our time’. Of the adjustment of any remaining inaccuracy there is no record.
The Númenóreans altered these arrangements. They divided the loa into shorter periods of more regular length; and they adhered to the custom of beginning the year in mid-winter, which had been used by Men of the North-west from whom they were derived in the First Age. Later they also made their week one of 7 days, and they reckoned the day from sunrise (out of the eastern sea) to sunrise.
The Númenórean system, as used in Númenor, and in Arnor and Gondor until the end of the kings, was called Kings’ Reckoning. The normal year had 365 days. It was divided into twelve astar or months, of which ten had 30 days and two had 31. The long astar were those on either side of the Mid-year, approximately our June and July. The first day of the year was called yestarë, the middle day (183rd) was called loëndë, and the last day mettarë; these 3 days belonged to no month. In every fourth year, except the last of a century (haranyë), two enderi or ‘middle-days’ were substituted for the loëndë.
In Númenor calculation started with S.A. 1. The Deficit caused by deducting 1 day from the last year of a century was not adjusted until the last year of a millennium, leaving a millennial deficit of 4 hours, 46 minutes, 40 seconds. This addition was made in Númenor in S.A. 1000, 2000, 3000. After the Downfall in S.A. 3319 the system was maintained by the exiles, but it was much dislocated by the beginning of the Third Age with a new numeration: S.A. 3442 became T.A. 1. By making TA. 4 a leap year instead of TA. 3 (S.A. 3444) 1 more short year of only 365 days was intruded causing a deficit of 5 hours, 48 minutes, 46 seconds. The millennial additions were made 441 years late: in T.A. 1000 (S.A. 4441) and 2000 (S.A. 5441). To reduce the errors so caused, and the accumulation of the millennial deficits, Mardil the Steward issued a revised calendar to take effect in T.A. 2060, after a special addition of 2 days to 2059 (S.A. 5500), which concluded 51/2 millennia since the beginning of the Númenórean system. But this still left about 8 hours deficit. Hador to 2360 added 1 day though this deficiency had not quite reached that amount. After that no more adjustments were made. (In T.A. 3000 with the threat of imminent war such matters were neglected.) By the end of the Third Age, after 660 more years, the Deficit had not yet amounted to 1 day.