Single unmarked glass. In cylindrical frame with rotating sleeve. Sleeve and inner frame each have two windows with scalloped edges. When the sleeve is rotated so that the windows are aligned, one can see the sand glass. Rotating the sleeve another 90 degrees seals up the glass in order to protect it from the elements during travel or at sea. Concentric circles on top and bottom of frame. Salmon-colored effluence. This may be a log glass.