Writings on the Vacuum and the Weight of Air
These writings record how Pascal repeated and varied Torricelli’s experiment with tubes of mercury, water and wine, and argue that the liquid column is held up not by nature’s horror of a vacuum but by the weight of the surrounding air. The posthumous treatises extend this into a general account of fluids in equilibrium, including the principle behind the hydraulic press.
Understanding the text
The New Experiments Concerning the Vacuum appeared in 1647 and drew Pascal into a dispute with the Jesuit Étienne Noël, who denied that empty space could exist. In 1648 his brother-in-law Florin Périer carried the tube up the Puy de Dôme and found the mercury lower at the summit. The treatises on fluids and air, finished around 1654, were published by Périer in 1663.
Key points
- 01
Burden of proof
Agreement with many phenomena never proves a hypothesis, whereas a single contrary phenomenon is enough to show that it is false.
- 02
Weight of air
Because the column falls with altitude, the effects once ascribed to a horror of the vacuum follow from the pressure of the air.
- 03
Equilibrium of fluids
Pressure on an enclosed liquid is transmitted in every direction, so a small force on a narrow piston can balance a large one.
Explore the ideas in depth
Experiment against authority
Reconstruct the experiments on the vacuum and Pascal’s rules for testing a hypothesis against the phenomena.
Situating the text
The New Experiments Concerning the Vacuum appeared in 1647 and drew Pascal into a dispute with the Jesuit Étienne Noël, who denied that empty space could exist. In 1648 his brother-in-law Florin Périer carried the tube up the Puy de Dôme and found the mercury lower at the summit. The treatises on fluids and air, finished around 1654, were published by Périer in 1663. These writings record how Pascal repeated and varied Torricelli’s experiment with tubes of mercury, water and wine, and argue that the liquid column is held up not by nature’s horror of a vacuum but by the weight of the surrounding air. The posthumous treatises extend this into a general account of fluids in equilibrium, including the principle behind the hydraulic press.
Following the arguments
Burden of proof : Agreement with many phenomena never proves a hypothesis, whereas a single contrary phenomenon is enough to show that it is false. Weight of air : Because the column falls with altitude, the effects once ascribed to a horror of the vacuum follow from the pressure of the air. Equilibrium of fluids : Pressure on an enclosed liquid is transmitted in every direction, so a small force on a narrow piston can balance a large one.
Continuing the reading
Read the account of the Puy de Dôme experiment with the reply to Father Noël, then the fragment of a preface on the vacuum, which contrasts progress in the sciences with authority in theology. The New Experiments Concerning the Vacuum appeared in 1647 and drew Pascal into a dispute with the Jesuit Étienne Noël, who denied that empty space could exist. In 1648 his brother-in-law Florin Périer carried the tube up the Puy de Dôme and found the mercury lower at the summit. The treatises on fluids and air, finished around 1654, were published by Périer in 1663.
Questions to carry into your reading
- Why does one contrary phenomenon count for more than many that agree?
- Where does Pascal draw the line between questions settled by reason and questions settled by authority?
In physics a hypothesis answers to experiment, while Pascal still leaves authority its own domain in theology.
How to read it
Read the account of the Puy de Dôme experiment with the reply to Father Noël, then the fragment of a preface on the vacuum, which contrasts progress in the sciences with authority in theology.
Editions & sources
Summaries and key points are original editorial interpretations. They accompany reading the work and do not replace an edition of the text. Editorial method ↗