But the original division of the day, probably Chaldæan, was strictly sexagesimal. It was divided into 60 parts (= 24 minutes), each part into 60, and this again into 60.
In medieval times the Sun’s daily path was divided into 24 hours, each of 15 degrees; and each hour was also divided into 3 miles or mileways of 5 degrees (= 20 minutes). This division was connected with the popular concrete idea of time in which 20 to 24 minutes was the common unit. In India the popular unit is still the time required to boil a pot of rice (20 to 24 minutes) or do some similar domestic task. In the Middle Ages the Western unit was the time required to walk a mile, on medieval roads.
‘And thogh I stonde there a myle’ (Gower, 1390).
‘And maketh every minute seem a myle’ (Spenser, 1594).
Then the degree was divided sexagesimally into 60 minutes each of 60 seconds, as at present. These divisions were at first called scruples, from the above-mentioned division of the day into 60 scruples of 24 minutes (the ounce being divided into scruples each of 24 light grains). Here the scruple-sense of 1/24 passes to 1/60.
‘1610. The latitude fiftie degrees and fortie scruples or minutes’ (Quot. _N.E.D._).
The hour was also divided similarly into 60 scruples or minutes, each of 60 second scruples or seconds.
The ounce and scruple division of time is shown in the following passage from ‘Le Breviari d’Amor,’ a thirteenth-century poem by Ermengaud, a monk of Beziers. I have freely translated it from the Languedocian. ‘The day is divided into quarters, each of 6 hours; and the fourth part of an hour is a point, the tenth part of which is a moment; the moment is divided into 12 parts called ounces, and each of the ounces yields 47 atoms, which time called an atom cannot be further divided.’ It seems almost certain that ‘atomus xlvij’ is either a mistake for xlviij or deliberately put for _set_ (7), to rime with _ret_ (yields). The ounce of time, = 7-1/2 seconds, would be divided into 24 scruples and 48 oboli, called atoms as being the end of the division. Similar dropping of a unit from Roman numerals is to be found in medieval Acts of Parliament and Ordinances.
In the lunar year used by Moslems and Jews, and also recognised by law in the movable date of Easter and some other feasts, the month is approximately of 29-1/2 days, so that the year is 354 days, less than the solar year by 11 days, or 12 in leap years. Hence Moslem feasts or fasts, such as the Ramadán and the times of pilgrimage, are that number of days earlier each year.