In 1796 Korenori TSUTSUMI noted in "Korenori Jikken-ki (Diary)"that he, standing waist deep in the water, measured the stone chamber and found that it was 3 jyo (about 30.3 centi meters) in length and 1.5 jyo in width.
1796年（寛政8）の惟徳実見記で堤惟徳（つつみこれのり）は水が腰に及ぶ中、玄室の長さを3丈、幅1丈半と計測した。