  Sunspot observations with telescopes in 18th century were carried out in
Japan as well. One of these sunspot observations is recorded in an account
called Sansaizusetsu narabini Kansei irai Jissoku Zusetsu (Charts of Three
Worlds and Diagrams of Actual Observations since Kansei Era). We analyze
manuscripts of this account to show in total 15 sunspot drawings in 1749-1750.
These observations were carried out by contemporary official astronomers in
Japan, with telescopes covered by zongurasus (< zonglas in Dutch, corresponding
to "sunglass" in English). We count their group number of sunspots to locate
them in long-term solar activity and show that their observations were situated
around the solar maximum in 1749 or 1750. We also computed their locations and
areas, while we have to admit the difference of variant manuscripts with one
another. These observational records show the spread of sunspot observations
not only in Europe but also in Japan and hence may contribute to crosscheck or
possibly improve the known sunspot indices.
