落とし懸けという,木製火鉢の内側にはめて灰や火を入れるための金属板製の客器

a metal pan in a wooden hibachi, used to insert fire or ash, called 'otoshigake' - EDR日英対訳辞書

19通の割り印つきの封筒を郵便で送って、中身を透視して返送してもらうものだったが、「透視」されて返却されたのは七通で、残りのうち三通は「うっかり火鉢に落として燃えた」、他は「疲れて出来ない」ということだった。

He sent her 19 envelopes with tally impressions by mail, telling her to see through the contents and send them back to him; however, she sent back the 7 of them which she tried 'toshi,' mentioning that the 3 as 'she carelessly dropped them into a hibachi brazier and were burnt,' and as to the rest that 'she was too tired to do the job.' - Wikipedia日英京都関連文書対訳コーパス