Heitengi (平天儀)

Heitengi is an astronomical volvelle, which is consisted of five parts; four of which are rotatable. By rotating the discs, you are able to figure out things like the paths of the sun, the moon, stars and the ebb and flow of the tide. The right page provides a general explanation of each components of the volvelle in Kanji and Katakana.

It was created in 1801(Kyowa 1st) by a Japanese telescope manufacturer, Iwahashi Zenbē (referred as Iwahashi Yoshitaka in the Tokugawa map collection).

According to Christie’s, one of Heitengi was priced at US$10,625, albeit our version at UBC seems slightly different.

Who was Iwahashi Zenbē(岩橋善兵衛)?

Iwahashi Zenbē(1756-1811) was born in today’s Osaka as a son of a fish dealer family. As mentioned above, he was a very famous telescope manufacturer in the late Edo period. His telescopes were quite well made (considered to be one of the best at that time) and they were used by many astronomers of the time. It even contributed greatly to the surveying project of Inō Tadataka who was working on the first map of Japan by using modern surveying techniques.  It is not certain how he was able to produce such good quality lens, however, reseachers speculate that he self studied through examining the Dutch telescopes. His telescope manufacturing business was succeeded to his family for five generations.

Heitengi Zukai(平天儀図解)

Heitengi Zukai was published the following year in 1802, as a supplementary book to Heitengi. This book gives the instruction of Heitengi in detail. It was also like a beginner’s guide to astronomy. It contained his view of the universe along with many illustrations.

Cover page of Heitengi Zukai
Pg.66-67 from Heitengi Zukai

First layer: 第一紙

Screen Shot 2018-03-28 at 0.32.18It is the smallest component of the volvelle and it shows the northern hemisphere from above(the north pole being the centre).

Japan and Africa are coloured in green. China, North America and Arabian Peninsula are in pink. The rest of the Asia and South America are in red. Korea and Europe are in yellow. However, it is interesting that Netherlands is purposely coloured in red.

Second Layer: 第二紙Screen Shot 2018-03-28 at 1.03.17

It is described as 月ノ天 in the explanation on the right page. In the window, it indicates the phase of the moon. When it is almost completely black as in the picture on the left, it means that that the moon is waning crescent.

The pale blue part shows the ebb and flows of the tide. 満(man) is when the tide is at the highest. 干(kan) is when the tide is at the lowest.

Third layer: 第三紙 Screen Shot 2018-03-28 at 1.04.18

It is named as 日ノ天 in the explanation on the right page. The inner circle(white) indicates the date in lunisolar calendar≒月齢(getsurei) + 1

The window of the outer circle(yellow) reveals 二十四節気 or a solar term in English. By rotating this disc, you are able to find the month of lunisolar calendar.

It also tells which constellations(depicted in the fourth layer) the sun is close to.

Fourth layer: 第四紙 Screen Shot 2018-03-28 at 1.41.47

It is named as 二十八宿ノ天 in the explanation on the right page. 二十八宿 or twenty eight mansions in English is a Chinese constellations system. They are depicted in both Kanji and the actual drawing of the constellations.

The inner part of the circle is divided into a little over 360 scales. (I am not sure whether this signifies 360 degrees or 365 days.)

Fifth layer: 第五紙Screen Shot 2018-03-28 at 1.42.33

This is the larget but the only circle that is not rotatable and it shows time and directions using the Chinese zodiac.

The top half of the circle is white, which signifies daytime. The bottom half of the circle is black, which signifies nighttime.

午 on the very top is horse, meaning south and 11:00am to 1:00pm.

子 on the very bottom is rat, meaning north and 11:00pm to 1:00am.


Let’s Use Heitengi!


I have created a video, which explains how to use Heitengi.

Click here to watch the video!



Date, Eitaro, ” lwahasi-Zenbei’s telescopes of 140 years ago 百四十年前岩橋善兵衛氏の作りし望遠鏡 (幕末天文学史特輯)” vol. 13 no. 142 (1933): 53-56. accessed April 22, 2018. http://hdl.handle.net/2433/162316

Kobayashi, Eisuke. “岩橋善兵衛” 江戸時代の天文学【10】vol. 21 no. 1 (2009): 20-24. accessed April 22, 2018. https://tenkyo.net/kaiho/pdf/2009_01/2009-01-06.pdf

“JAPANESE ASTRONOMY — Heitengi (Astronomical Volvelle). Izumi province?, southern Osaka: Iwahashi Kobodo, Jokyo 1 [1801].” Christie’s. Accessed April 22, 2018. https://www.christies.com/lotfinder/Lot/japanese-astronomy-heitengi-astronomical-volvelle-izumi-5388586-details.aspx

juntag00. “平天儀 演義.wmv”. Youtube video, 7:18. Posted [July 2010]. https://www.youtube.com/watch?v=NF2tPT5_DkQ&t=6s&index=1&list=LLauGAkkANvSbqOqZYaqWUWQ