I’ve been watching Tudor Monastery Farm recently, and have found it just as interesting as the other historical series done by the same team. In episode 3, there was a fascinating bit about some of the earliest mechanical clocks. These were used in monasteries from the 13th Century to regulate the times of monastic offices, and ring a bell to call the monks to prayer at the appropriate times.

They needed to have seven offices during the day and one at night, but since the length of the day (and night, correspondingly) changed with the length of daylight over the seasons, this caused a problem. If they kept the measurement of an hour the same across the year, some of the offices would be incorrectly rung after dark in winter, and in summer, all of the offices would occur during the day. The way they got around this is fascinating: they stretched and compressed the hours to fit the length of daylight across the seasons. The clocks had a mechanism called a verge and foliot that regulated the speed of the clock by means of weights placed at different distances along the length of the foliot, which was a horizontal bar. By adjusting the weights, they could stretch the ‘hours’ in summer so that the interval between hours would be longer, and compress them in winter. Regardless of the length of the day throughout the seasons, each office would be rung at roughly the same fraction through the solar day.

I really like this idea. In summer, when there’s abundant light and warmth and you are full of energy and busy with lots of tasks, you would be able to get more done in each hour of the day. In winter, the hours would be shorter, but you had less to get done each day. I think it’s eminently sensible to regulate and adapt your measure of the day to the length of daylight. I wonder if, subjectively, people felt that the hour was about the same length between summer and winter, despite being an objectively longer interval in summer? If you are busy, time passes more quickly, so the longer hours might have seemed about the same length as the shorter, but more boring, winter hours.

Now that we have abundant artificial light, and many of us mainly work indoors, we have no need fit our working patterns to the movements of the sun, but I really wish we could. I have been very busy at work recently, and have been trying to force my brain and body to work on many hours after sunset, when my natural inclination is to finish at sunset, curl up in the warm and then go to bed early. I think we should bring back flexible hours — it would make for a much more pleasant working experience, and also save energy on lighting. However, since most people complain bitterly about having to move their clocks forward or back just one hour twice a year, I don’t think it’s going to happen.