Edo. The government first invited Asada for this work, but, due to illness, Asada was
unable to accept the post and recommended two of his students, Takahashi Yoshitoki
(高橋至時, 1764–1804) and Hazama Shigetomi (間重富, 1756–1816). Asada himself stayed in Osaka and died in 1799 at age 65.
Takahashi was born the son of a lower-class official (同心, a policeman) in
Osaka. From his youth, Takahashi was interested in mathematics. In 1779, he took
over his father’s position and studied in his spare time at Asada’s Senjikan.
Takahashi found common interest with a wealthy pawnbroker and instrument
maker named Hazama, who was also a student of Senjikan. Hazama was talented
in technology and built many astronomical and geodetic instruments, including a
reflecting telescope and a spherical armillary.
Both Takahashi and Hazama moved to Edo in 1795 and started observations at
Asakusa Observatory for carrying out calendar reform. The new calendar was
completed in 1797 and was called the Kansei calendar (寛政暦). It was officially
put into operation in 1798.
The Kansei calendar was based largely on the sequel to the Li-Hsian K’ao Ch’eng
(暦象考成総編, Compendium of Calendrical Science and Astronomy), which was
chiefly edited by the German missionary Ignatius Kögler (1680–1746) and made use
of the elliptical orbit of the Sun without reference to the heliocentric system.
Takahashi was really the first to apply the elliptical theory. For planetary motions,
however, Takahashi and Hazama applied the Tychonic epicyclic system, following
the original Li-Hsian K’ao Ch’eng (暦象考成).
Just after completing the Kansei calendar, Takahashi encountered the Dutch
version of J. J. L. de Lalande’s Treatise on Astronomy (five volumes). He was
greatly impressed by this book and the comprehensive achievements of Western
astronomy with respect to planetary theory and mathematical technique. Takahashi
wrote a multivolume work entitled Lalande Rekisho Kanken (ラランデ暦書管見, A
Private Review of Lalande’s Astronomy, 1803) and began to translate this book, but
the work remained unfinished at the time of his death in 1804 (Nakayama 1972).
This work was taken over by his sons.
1.2.4 Tenpo Calendar
The complete translation of Lalande’s book was completed in 40 volumes by
Yoshitoki’s two sons, Tekahashi Kageyasu (景保) and Shibukawa Kagesuke (渋
川景祐). The translation was published in 1836 under the title Shinko Rekisho (新巧
暦書, Astronomy by the New Technique) and represented the highest level of
astronomy in China and Japan at the time. In 1841, the Tokugawa government
ordered to Shibukawa Kageyasu and his group, including Yamaji Kaiko (山路諧孝)
and Adachi Shinto (足立信頭), to undertake calendar reform. The calendar was
completed in 1842 and named the Tenpo calendar (天保暦), which was promulgated
in 1843 (Uchida 1986).
1.2 Calendar Reforms
5
unable to accept the post and recommended two of his students, Takahashi Yoshitoki
(高橋至時, 1764–1804) and Hazama Shigetomi (間重富, 1756–1816). Asada himself stayed in Osaka and died in 1799 at age 65.
Takahashi was born the son of a lower-class official (同心, a policeman) in
Osaka. From his youth, Takahashi was interested in mathematics. In 1779, he took
over his father’s position and studied in his spare time at Asada’s Senjikan.
Takahashi found common interest with a wealthy pawnbroker and instrument
maker named Hazama, who was also a student of Senjikan. Hazama was talented
in technology and built many astronomical and geodetic instruments, including a
reflecting telescope and a spherical armillary.
Both Takahashi and Hazama moved to Edo in 1795 and started observations at
Asakusa Observatory for carrying out calendar reform. The new calendar was
completed in 1797 and was called the Kansei calendar (寛政暦). It was officially
put into operation in 1798.
The Kansei calendar was based largely on the sequel to the Li-Hsian K’ao Ch’eng
(暦象考成総編, Compendium of Calendrical Science and Astronomy), which was
chiefly edited by the German missionary Ignatius Kögler (1680–1746) and made use
of the elliptical orbit of the Sun without reference to the heliocentric system.
Takahashi was really the first to apply the elliptical theory. For planetary motions,
however, Takahashi and Hazama applied the Tychonic epicyclic system, following
the original Li-Hsian K’ao Ch’eng (暦象考成).
Just after completing the Kansei calendar, Takahashi encountered the Dutch
version of J. J. L. de Lalande’s Treatise on Astronomy (five volumes). He was
greatly impressed by this book and the comprehensive achievements of Western
astronomy with respect to planetary theory and mathematical technique. Takahashi
wrote a multivolume work entitled Lalande Rekisho Kanken (ラランデ暦書管見, A
Private Review of Lalande’s Astronomy, 1803) and began to translate this book, but
the work remained unfinished at the time of his death in 1804 (Nakayama 1972).
This work was taken over by his sons.
1.2.4 Tenpo Calendar
The complete translation of Lalande’s book was completed in 40 volumes by
Yoshitoki’s two sons, Tekahashi Kageyasu (景保) and Shibukawa Kagesuke (渋
川景祐). The translation was published in 1836 under the title Shinko Rekisho (新巧
暦書, Astronomy by the New Technique) and represented the highest level of
astronomy in China and Japan at the time. In 1841, the Tokugawa government
ordered to Shibukawa Kageyasu and his group, including Yamaji Kaiko (山路諧孝)
and Adachi Shinto (足立信頭), to undertake calendar reform. The calendar was
completed in 1842 and named the Tenpo calendar (天保暦), which was promulgated
in 1843 (Uchida 1986).
1.2 Calendar Reforms
5