1) Laboratory glassware 
A half hour sand glass used keep time during the watches.
A watch glass is a circular concave piece of glass used in chemistry as a surface to evaporate a liquid, to hold solids while being weighed, or as a cover for a beaker. The latter use is generally applied to prevent dust or other particles entering the beaker; the watch glass does not completely seal the beaker, and so gas exchanges still occur. W...
[n] - laboratory glassware