
A sketch (Ѻ) of the so-called “Torricellian space” or region above the Torricelli barometer; a topic of much philosophical debate from 1644 into the 1670s.

A sketch (Ѻ) of the so-called “Torricellian space” or region above the Torricelli barometer; a topic of much philosophical debate from 1644 into the 1670s.

In science, Torricellian space refers to the region or empty area left at the top of a tube if mercury when inverted into a large tub of mercury, as in the Torricelli barometer. [1]

Overview
In 1660, Robert Boyle, in his New Experiments (pg. 9) was citing Johannes Kepler as estimating the height of the atmosphere to be 8 miles and Giovanni Riccioli (Ѻ) saying it might be 50 miles. Today we defined the Karman line to be 62 miles in height.

Quotes
The following are related quotes:

“For Descartes, the mercury was sustained by the weight of the atmosphere, but the Torricellian space was filled by some form of subtle matter. For Descartes’ inveterate opponent Roberval, the Torricellian space was indeed empty, but the height of the mercury depended upon the limit of the horror of the vacuum (horror vacui).”
— Steven Shapin (1985), Leviathan and the Air Pump [1]

References
1. Shapin, Steven; Schaffer, Simon. (1985). Leviathan and the Air Pump: Hobbes, Boyle, and the Experimental Life (Torricellian space, 5+ pgs). Princeton, 2011.