Kaishu KATSU at the age of 25, who aimed at ascetic practices of Western studies, rented "Doeff Halma" at the cost of 10 ryo (a currency unit) a year (equivalent of about 1.2 to 1.3 million yen) from a doctor of Dutch medical science, Genii AKAGI, despite his poverty, and he devoted one year to producing two copies of its manuscript while making the ink that did not blot, or the pen by shaving the feathers of birds.
蘭学修行を志した25歳の勝海舟は、貧窮にもめげず赤城玄意という蘭医から『ドゥーフ・ハルマ』を年10両（約120～130万円に相当）で借り受け、滲まないインクや鳥の羽根を削ったペンを自作しながら1年がかりで写本2部を製作した。