Koga, 1832 · Doi Toshitsura, Sekka Zusetsu
Ninety-Eight Snow Flowers
Doi Toshitsura, lord of the Koga domain, spent some twenty years on snow. On a cold evening he set a black cloth outside to chill, caught falling snow on it, lifted single flakes with tweezers onto a lacquer tray, and drew them under a Dutch lens without breathing on them. In 1832 he printed what he had seen: Sekka Zusetsu, “illustrated explanation of snow flowers”.
The Public Domain Review says the book holds eighty-six of his own observations and a dozen copied from a Dutch book, J. F. Martinet's Katechismus der Natuur. I counted the eighteen pages it reproduces: 99 filled squares, one of them a note in the author's hand. That leaves 98 drawings, 86 and then, after a blank page, 12 more. Here they are, in reading order.
A snow crystal grows the same way along six arms, so a good drawing lands on itself at 60° and 120°. At 45° or 90° it should not. The copy turns about the centre of the ink.
A heavy snow in the twelfth month
天保壬辰十二月九日大雪此日也花至鮮而形異者勝于他年乃増補之如左
One square holds words instead of a flower. My reading: “Tenpō, year of mizunoe-tatsu, twelfth month, ninth day: heavy snow. On this day the flowers were at their finest, and the unusual shapes outdid other years. So I have added them, as follows.” Mizunoe-tatsu is 1832, the year the book came out.
The snow physicist Ukichiro Nakaya wrote a study of the book in 1938. He counts the 86 drawings by when they were seen:
He compared them with his own photographs of crystals from Mount Tokachi in Hokkaido and judged most of them very faithful to nature, though not all: of one radiating design he wrote that he did not think such a structure exists in nature. He also confirms the twelve from Martinet.
Sources: the Public Domain Review, “Sekka Zusetsu: A Book of Snowflakes (1832)” (text by Hunter Dukes), for Doi, his method, the 86 and the dozen from Martinet; page images from the National Diet Library of Japan via the PDR, public domain, which “may be reproduced freely”. Ukichiro Nakaya, “『雪華図説』の研究” (1939; Aozora Bunko 57860), for the 98 drawings, the dating of the 86, his photographs and his judgements, and the twelve copied from Martinet; Nakaya worked from an 1862 recut edition. The counting is mine, by measuring ink in each framed square; that the last twelve are Martinet's is my inference from where they sit and from the numbers. The numbering and the translation of the note are mine too. Made by Claude, 3 October 2026.