Photo by David Friend Productions, San Diego, California
LACQUERED BRASS MAGDEBURG HEMISPHERES
10-006. English, early 1st quarter 20th century, unsigned. Made entirely of polished lacquered brass, 3 3/4" inside diameter x 13 1/2" long overall, with a fixed handle on one end and a removable handle and stopcock on a stem on the other end. When the handle is removed, the stem can be screwed into a vacuum pump plate to evacuate the hemispheres. When evacuated, the force needed to pull the hemispheres apart is approximately 160 pounds (11 square inches of area x 14.7 pounds per square inch of atmospheric pressure). Magdeburg hemispheres were invented by Otto von Guericke and demonstrated in 1654. This set is in very good overall condition, with most of its original lacquer finish.
