Dark part of the moon

Someone named Gruithuisen reported, in Sci. Amer. Sup., 7-2712, that at 5 a.m. on Oct. 20, 1824, a light was seen upon the dark part of the moon. It disappeared, and six minutes later it reappeared. It disappeared again, then flashed intermittently until 5:30 a.m., when sunrise ended the observations.

–Charles Fort, New Lands, p395 (The Complete Books of Charles Fort, Dover, c1974).