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"Air pump" by Robert Boyle (detail)
"Air pump" by Robert Boyle (detail)

Experiments on the spring of the air

You have seen in the previous steps that the theological and metaphysical convictions can interfere with the scientific practice in various ways: in how the experiments are designed, which questions are asked, but also in reading and interpreting of the experimental results.

Read the following texts and think about the points of agreement and disagreement between the three authors, Robert Boyle, Francis Linus, and Henry More, regarding the possibility of creating void and the theory according to which air can be unequal (what is called the string theory):

It has been admired by very ingenious Men, that if the exquisitely polished surfaces of two flat pieces of marble be so congruous to each other that from their mutuall application there will result an immediate contact, they will stick so fast together, that he that lifts up the uppermost, shall, if the undermost be not exceedingly heavy, lift up that too, and sustaine it aloft in the aire. A probable cause of this so close adhesion we have elsewhere endeavoured to deduce from the unequall pressure of the Air upon the undermost stone; for the lower superficies if that stone being freely exposed to the Air is pressed upon by it, whereas the uppermost surface, being contiguous to the superior stone, is thereby defended from the pressure of the Air which consequently pressing the lower stone against the upper, hinders it from falling, as we have elsewhere more fully declared. (…) But what we may learn from our own Engine, that two bodies, though they touch each other but in a small part of their surfaces, may be made to cohere very strongly, only by this, That the Air presses much more forcibly upon the inferior superficies of the lowermost Body, then upon the upper surface of the same.

A. Robert Boyle, New Experiments Physico-Mechanical touching the String of the Air, experiment 31, printed by H. Hall, 1660, pp. 229-230.

Since, when falling, the lower stone would have to disconnect simultaneously from the whole of the upper surface, nor could the neighbouring air insinuate itself into the whole remaining space, it is necessary that the stone would descend in no other way than by leaving after itself a fine substance, which mercury or water leave behind them when descending this way. Yet since such a substance is separated from the marble with more difficulty than from mercury, or any other fluid body, it thence follows that it adheres here so tenaciously. (…) I do not deny there to be some weight in the air, and even elasticity, or a force or regaining its extension if it be reduced to a smaller space (…); however, I deny that in this was it may have enough gravity or elasticity as are imagined.

B. Francis Linus, Tractatus de corpus inseparabilitate, XVI, printed by T. Roycrost, 1661, pp. 125-126 (trans. Steven Shapin and Simon Schaffer, Leviathan and the Air Pump, Princeton University Press, p. 160).

[N]either the Aire it self, nor any more subtile and Divine Matter (which is more throngly congregated together in the Receiver upon the pumping out of the Aire) has any freedome of will, or any knowledge or perception to doe any thing, they being so puzzel’d and acting so fondly and preposterously in their endeavours to replenish the Receiver again with Aire. For if the external Aire and that subtiler Matter in the Receiver had been knowing and free Agents, there would have been that Correspondence between them, that the Exteriour Air would have suspended or withdrawn its pressure without, and the subtile and Divine Matter within would have directed its motion against the Stopple and Valve to let in the Air, according to the intention of Nature. Or if noting but that Subtile body be free and knowing, that alone by mutual Correspondence (that in the Aire without bearing off the pressure of the outward Aire against de Receiver, & that part within bearing against the Valve or Stopple) would let in the Aire, according to the earnest and serious purpose of Nature.

C. Henry More, An Antidote against Atheism, II, 2, 8, in A Collection of several Philosophical Writings, printed by J. Flesher, 1662, p. 44.

What are the differences in explaining the phenomenon produced in the air pump? Do the differences refer to the experiment itself or the theory attach to explaining it?

Please share your ideas and discuss them with other learners.

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This article is from the free online course:

The Scientific Revolution: Understanding the Roots of Modern Science

University of Groningen

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