Atom comes from a Greek word meaning “uncuttable,” and so in terms of physics an atom is literally an “indivisible” particle. In Old English, however, atom also came to be used for what was then considered the smallest measureable quantity of time: there were once reckoned to be 376 atoms in a minute, making one atom equal to a little under 1/6th of a second (or 0.15957 seconds, to be more precise).
In the Middle Ages, all kinds of contraptions and devices were used to keep track of time, one of the simplest and neatest of which was an Indian water-clock called a ghurry. It comprised a large metal or wooden bowl, pierced with several holes, which would be placed in a basin full of water, and as the water poured into the bowl through the holes in its sides, it would slowly sink to the bottom of the tank. The entire process from start to finish took a fixed amount of time, which was usually precisely 24 minutes. Ultimately, there were once considered to be 60 ghurries in a day.
Note: contraption 奇妙的装置，新奇玩意儿
A lustre is a period of five years. Its use dates back to Ancient Rome, when a lustrum was a five-year period at the end of which a full census of the Roman population would be carried out. Once the figures were in and the counting was complete, a vast celebratory procession would be held through the streets of Rome, which culminated in a vast purifying sacrifice called a lustratio (literally, “a washing”) made in honor of all of the people of the Empire.
If a “light-year” sounds like a unit of time but is actually a unit of distance, then a mileway is the complete opposite. It sounds like a unit of length, but in the early Middle Ages it was actually a name for a period of around 20 minutes—or roughly the amount time it takes to walk one mile.
A nundine was a Roman market held every ninth day, which takes its name from the Latin word for “ninth,” novem (as in November, the ninth month of the Roman calendar). A nundine, ultimately, is a period of nine days—or, not counting inclusively, an eight-day gap between two dates.
Note: nundine 根据古罗马历法，每九天举行一次的集市日
Derived from the Greek words for “night” (nyks) and “day” (hemera), a nychthemeron is nothing more than a fancy alternative name for a period of 24 hours.
Note: nychthemeron 一天一夜，一昼夜
Also called a point or a prick, in Medieval Europe a punct was a quarter of an hour…
“A punct”也被称为“a point(一点)”或“a prick(一刺)”，在中世纪的欧洲，一“punct”表示一刻钟……
…while a quadrant is one-quarter of a day, or a period of exactly six hours.
Note: quadrant 四分之一圆(或圆周)，象限
Quinzième literally means “fifteenth” in French, and in this sense the word was borrowed into English after the Norman Conquest of England as the name of a tax or duty equivalent to 15 pence in every pound. In the early 1400s, however, the word began to be used in religious contexts to refer to the day of a major church festival or holiday and the first two full weeks following it. As a result, a quinzième is a period of 15 days.
Scruple comes from scrupulus, a Latin word for a small stone or pebble. Historically, a scruple was also an old apothecaries’ measurement equal to 1/24th of an ounce (roughly 1.3 grams). In the early 17th century scruple also came to be used as another name for 1/60th of a degree of a circle (i.e. one minute), 1/60th of a minute (i.e. one second), and 1/60th of a day (i.e. 24 minutes).