Telescopes in Edo-Period Japan

"Young Woman Looking Through a Telescope" by Edo artist Katsushika Hokusai (1760-1849). (Visipix.com)

During the Edo period in Japan (1603-1868), a device came from Europe to Japan that revolutionized science and astronomy, helped change the calendar, and became a hot novelty item among the public. That device was the telescope.

The first refracting telescope (which was the type of telescope most widely used by the public before the reflecting telescope started becoming more popular over the past century) was brought to Japan in 1614 during a mission to open trade between England and Japan. That telescope was presented as a gift to the shogun Tokugawa Ieyasu from the English captain John Saris and one of his sailors,William Adams.

A few years later, the first homemade telescope was made by Tohichi Ikushima. Unfortunately, this milestone also led to telescope manufacturing being initially banned in Japan by the Tokugawa shogunate due to its dual purpose as a military application.

In 1659, telescopes received their first major military usage when they were used at three different observation towers set up along Japan's coast for observing foreign ships arriving in Japanese waters.

According to Peter Abrahams's in-depth history of the Japanese telescope, it was used throughout the course of the 17th and early 18th centuries mainly for terrestrial purposes, such as measuring angles and military observation. Over the course of the 18th century, more and more of the general Japanese public, including astronomers, would use the telescope for observing the nighttime skies. The telescope was used by Edo astronomer and government official Harumi Shibukawa when, in the early 18th century, he discovered a series of new stars and added them to the traditional Chinese celestial map, which had been used for centuries. This new celestial map, named the "Tenmon Seisho-zu", became the foundation of modern Japanese astronomy.

After the creation of the new map, new advances were made in Japanese astronomy, such as a new set of celestial globes by Shibukawa and the creation of a new "lunisolar" calendar. Astronomy became a popular subject of study for the country's intelligentsia. All of these advances were helped in 1720 by the Tokugawa lifting their ban on scientific research from the West that had no religious implications. However, the Tokugawa shogunate made the priority of the nation's new science not of mapping the galaxies, but for making new calendars to justify its own power and prestige.

Throughout the 17th and 18th centuries, the Japanese learned about the art of the telescope from the Dutch, who also imported their own telescopes and telescope parts such as lenses. Also during the 1700s, a number of Japanese astronomers and artisans started making their own telescopes. By the end of the century, homemade telescopes and lenses were very commonplace.

During the late 18th and early 19th centuries, the telescopes made in Japan started catching up to the Western models that were imported to Japan. The famed telescope-maker Zenbei Iwahashi's (1756-1811) refracting telescope from the late 1700s was equal - and possibly superior to - the Western telescopes which were the standard of the time! Also during the early 19th century, the Asada school, founded by astronomer Asada Goryu (1734-1799), created modern astronomy instruments and used Iwahashi's telescopes for their observations. These and other developments set the basis for the optical industry in Japan - a tradition that continues today with Japan's leading camera and optical equipment manufacturers.

Kunitomo Ikkansai's telescope, c. 1832. (Wikimedia Commons)

In 1833, after spending a little time in Edo (modern-day Tokyo) learning about telescopes from the Dutch, the ex-gunsmith Kunitomo Ikkansai created Japan's first Gregorian reflecting lens telescope. This telescope allowed him to make some very detailed observations of sun spots and the surface of the moon.

After the Tokugawa shogunate became a little less paranoid about the usage of telescopes, they became a popular novelty item among the public. Telescopes made their way into Japanese fiction such as kibyōshi (黄表紙). They were used by ordinary people for observing nature, nearby cities, and so on. Many ukiyo-e prints from the time depict ordinary people watching birds or observing ships at sea with telescopes. During the 19th century, crowds gathered at observation points to look out over mountains or the ocean.

Telescopes also became popular during the Edo period for gossip and voyeuristic purposes! As a matter of fact, some of the "pleasure districts" in Japanese cities offered telescopes for this very purpose.

In 1854, the Tokugawa shogunate opened Japan's borders to foreign trade. In 1868, the Tokugawa shogunate's rule came to an end and the Meiji Restoration began. During the Meiji period, Japan opened its doors to the outside world. The Meiji government formally adopted the solar calendar used by the West and Japanese astronomers were finally able to study the science of astronomy in full.

The telescope is an instrument that has become a part of our everyday lives, but in Edo-period Japan, it was instrumental in changing science and society.

For more about Japanese astronomy in the Edo period, here's another site you might want to visit:
http://teapot.lib.ocha.ac.jp/ocha/bitstream/10083/3391/1/P242-244.pdf