A recent addition to the Peabody’s History of Science and Technology collection harkens back to when religion, astronomy, and astrology together shaped Europeans’ understanding of time.
Yale Professor Emeritus Thomas Lentz, MD donated a rare perpetual calendar to the collection which might have been made in about 1580 in Nuremberg, Germany. It is an intricately engraved silver disc with plates which rotate to reveal information about time, astronomy, and the calendar. Professor Lentz is a curatorial associate and longtime donor for the collection.
“This is a real jewel, combining beautiful craftsmanship with many different types of knowledge,” said Alexi Baker, Ph.D., Collections Manager of the History of Science and Technology. “It is called a perpetual calendar because, in theory, it would work forever. Of course, it doesn’t work forever, but it should work for a good long time. And you can actually look up past, present, and future dates with it.”
The calendar is a little over two inches in diameter and consists of a central fixed disc with four rotating silver discs, riveted two to each side. You can set the day of the week, represented by an astronomical symbol, within the month. The front of the calendar shows the months of January to June, and the back shows July to December. There are important Christian dates including saints’ days engraved under each month.
“This instrument brings together calendrical information including important dates in the Christian faith, astronomical information like where the sun and moon will be on specific dates, and how much daylight you will be getting,” Baker said. “It’s combining the natural, religious, and astronomical knowledge and thought that shaped early modern Europeans’ perceptions and uses of time.”
The discs on the front of the calendar rotate to indicate the seasons, the day of the lunar cycle, and the hours and minutes of moonlight to be expected. They also reveal a little image of where the moon is in its phases, waxing and waning between New Moon and Full Moon.
The discs on the back of the calendar trace the path of the Sun over time. They reveal for each month the zodiac symbol of the constellation through which the Sun will appear to pass in the sky, the time of sunrise, and the length of day. The rotating discs also reveal the time of sunset each day and the length of night.
Baker explained that a metal engraver, who specialized in instruments like this and perhaps sundials and astrolabes, likely made this piece. “Based on its design, this calendar might have been made in Nuremberg, which was a real hotbed of artisanal and mathematical knowledge and skill in the early modern period. Professor Lentz has given us other amazing artifacts from the same place and time, from microscopes to vision aids,” she said.
A well-off individual would have bought a calendar like this. “Because it is silver and finely engraved, it was a somewhat more expensive object,” Baker said. “It would be something to show off to people and still enjoy yourself, but at the same time, it was practical. The original owner could have also been someone we would consider a professional or a religious figure.”
Historical objects like this offer tangible ways for students and researchers as well as the public to understand the past. The calendar has already been included in object-based university classes which take place at the Peabody Museum and is being considered for inclusion in an exhibition about time.
“You can approach this from many different angles,” Baker said. “The calendar can offer insight into early modern science, mathematics, fashion, technology, and of course religion and daily life. We can learn about the craftsmanship and international networks of materials and skills necessary to manufacture these instruments as well. Classes and museum visitors will look at pieces like this and often contrast them with today’s disposable culture. They are always surprised by how finely crafted and long-lasting many past technologies were.”
This and other artifacts from the History of Science and Technology collection, as well as from the museum’s Anthropology collections, reflect the changing perceptions and technologies of time over the centuries. When this perpetual calendar was made in Europe in the 1500s, most people understood and perceived the passage of time in terms of the natural rhythms of the sun and moon and how long it took for light sources such as candles to burn down.
There were early mechanical timekeepers, but they were not yet that accurate, and they were too expensive for most people to own. They also needed to be wound regularly to keep operating, and sundials were often used to reset their time. Baker explained that people continued to use sundials well into the 1880s, both at home and in public spaces.
“It was still largely a natural and religiously oriented conception of time,” she said. “Astronomy was both the mathematical and observational discipline and what everyone could see in the skies and experience with the changing light and seasons, and it was intimately intertwined with Christianity as well as with astrology for medicine and other uses. In some ways, this seems quite alien to how many of us experience time today, but there are also always surprising resonances between life centuries ago and life now.”
