Works and Days

I have taken the title of this post from Hesiod's book. Although I won’t talk about works here, I will talk about days. The word day has two different meanings: the whole day (24 hours) and the part of the day when there is sunlight. Thus, it could be said that

day = day + night

which seems absurd, for a mathematician could deduce that the night does not exist. Instead of that equation, and to make it clear that there are two kinds of days, we should use this expression:

day₁ = day₂ + night

Here, day₁ is a natural cycle, the period of the Earth's rotational motion around its axis. But then a problem arises: when can we say that the Earth has made one complete rotation around its axis? The problem is, to define the period of a moving object, it is necessary to have a reference point. The results will be different depending on which point is chosen.

The Clock in Strasbourg Cathedral

Clock of Strasbourg Cathedral

One of the most surprising instruments used to measure time is the clock of Strasbourg Cathedral, which contains a mechanical computer, a marvel made up of gears and cogwheels, a pinnacle of the instrumentation of that time, which could be considered comparable to Charles Babbage's Analytical Engine, except that it is not a programmable computing device, but a computing machine built for the specific purpose of calculating time. More details can be found in this article in the journal The Sciences of the New York Academy of Sciences.

The clock is inside the building, rather than at a tower, like those of many other cathedrals. It has a long history, as it dates back since the 14th century, although it was completely rebuilt in the 16th. By the end of the 18th century it stopped working. Legend says that, at the beginning of the 19th century, an orderly who was showing the cathedral to a group of visitors mentioned that the clock had not been working for a long time. Then a boy who was part of the group exclaimed: I will fix it! Forty years later, he did. That child would have been Jean-Baptiste Schwilgué, who remodeled the clock around 1840.