Swiss physicist and mathematician Daniel Bernoulli's 1738 pressure apparatus diagram. |
“At eight o'clock, we met in the gardens of the Minim Fathers, which has the lowest elevation in town. First, I poured 16 pounds of quicksilver into a vessel, then took several glass tubes, each four feet long and hermetically sealed at one end and opened at the other. Then placed them in the vessel of quicksilver. I found the quicksilver stood at 26" and 31⁄2 lines above the quicksilver in the vessel. I repeated the experiment two more times while standing in the same spot. They produced the same result each time. Taking the other tube and a portion of the quicksilver, I walked to the top of Puy-de-Dôme, about 500 fathoms higher than the monastery, where upon experiment, and found that the quicksilver reached a height of only 23" and 2 lines. I repeated the experiment five times with care. Each at different points on the summit, found the same height of quicksilver, in each case.”
“The weight P holding down the piston in [a given] position is the same as the weight of the overlying atmosphere, which we shall designate P in what follows.”
“The weight of air on the earth’s surface is as great as the weight of water about 20 Magdeburg cubits deep. In other words, if water should rise 20 cubits above the earth’s surface, the pressure it would exert on all things beneath is the same as the pressure of air.”— Otto Guericke (1663), Magdeburg Experiments on the Vacuum of Space (pg. 113)