Reproduction of Torricelli's experiment in 1644. Two glass tubes, 1 with a pear-shaped bulb, inverted and inserted into an open beaker. Mounted on wooden backboard with brass scale, divided 20-26 by 12ths, between tubes. Mercury in tubes would rise to same height despite differences in their tops. This illustrates that the height of the mercury is dependent on an outside force (air pressure) and not on any thing within the tubes.
