Oxford: printed by W[illiam]. Hall for R[ichard]. Davis, 1666.
Octavo: 16.2 x 10.5 cm. , 247,  p., With 3 folded plates. Collation: A8, a8, b2 (contents, imprimatur), B-Q8, R4
A fine copy in contemporary blind-ruled calfskin, front joint strengthened. Contents crisp with the only faults being: edges of imprimatur leaf and head of t.p. lightly browned, tiny tear to leaf D4 affecting the catchword, N1 with small burn hole. The three folding plates are in excellent condition. Provenance: 18th c. Latin inscription at head of title "Ex lib. Guilielmi Hunt Donum Gualterii Grubbe Armigeri 1714". Several other books are known with this same inscription, including “The Compleat Soldier” (1681). Possibly given to Hunt by Walter Grubbe MP, of Potterne, Wiltshire, died 1715.
“[Through his experiments in hydrostatics,] Robert Boyle provided a mechanical account of the features that distinguish liquids and air from solids and from each other. In his pneumatics, Boyle articulated his notion of the 'spring' of the air for that purpose. Pressure appeared there in a common, rather than in a technical, sense. It was when he turned to hydrostatics that Boyle found the need to introduce a technical sense of pressure to capture the fluidity of water which, unlike air, lacked a significant spring. Pressure, understood as representing the state of a liquid within the body of it rather than at its surface, enabled Boyle to trace the transmission of hydrostatic forces through liquids and thereby give a mechanical account of that transmission according to his understanding of the term. This was a major step towards the technical sense of pressure that was to be adopted in Newton’s hydrostatics and in fluid mechanics and thereafter.…
“Boyle had not focused on the issue of a theoretical characterization of liquids as distinct from solids and air in his ‘Spring of the Air’. In that work, Boyle distinguished air from solids by stressing that spring is distinct from weight, which solids and air alike possess, and that the spring of the air is distinct from elasticity in solids through being isotropic and being expansive only. Forces are transmitted mechanically from point to point in air on account of its spring. That is why Boyle had no need to develop a notion of pressure that went beyond the common sense one and which he could use to describe the forces exerted by air on solid surfaces. That standpoint could not work for liquids because they lack a corresponding spring, a fact that Boyle appreciated and had explored experimentally. He seems to have become aware of the theoretical challenge posed by liquids, as distinct from solids and air, after reading Pascal's ‘Equilibrium of Liquids’. His response was spelt out in ‘Hydrostatical Paradoxes made out by New Experiments (for the Most Part Physical and Easy)’ (1666).
“Apart from some minor qualifications, Boyle accepted the theoretical content of Pascal's hydrostatics as 'worthy of the author' . However, he had problems with the experimental evidence Pascal invoked in its support. He raised doubts about whether Pascal had performed the experiments he described and whether they could possibly be performed following Pascal's prescriptions. His doubts ranged from the probability that stoppers in apparatus as described by Pascal would leak to the observation that some of the experiments required that experimenters make extended observations twenty feet under water. He also pointed out the difficulty of readily reproducing Pascal's experiments due to the fact that many of them required large quantities of mercury and glass tubes over twenty feet in length. Boyle presented himself as an expositor of Pascal's hydrostatics seeking to clarify aspects of it by way of easy to perform experiments. He aimed to show how various hydrostatic phenomena, some of which can appear as 'surprising' and even 'abstruse' can be 'made out by new experiments (for the most part physical and easy)', as announced in the title of his tract.
“Near the beginning of Hydrostatical Paradoxes, Boyle characterized his objective as follows:
‘It not being my present task to deliver the elements, or a body of hydrostatics, but only ten or twelve paradoxes, which I conceive to be provable by this new way of making them out, I shall to avoid confusion, deliver them in as many distinct propositions; after each of which, I shall endeavour in a proof, or an explication, to show, both that it is true, and why it ought to be so.’
“It is clear from his earlier remarks that Boyle aimed to go beyond 'geometricians' such as Stevin who, in his opinion, had asserted various propositions to be true without showing how or why they are true. Boyle found the seeds of what he needed in this respect in Pascal's ‘Equilibrium of Liquids’. Pascal had indicated that hydrostatic forces are transmitted through liquids by virtue of their 'continuity and fluidity', giving rise to forces on bounding surfaces that are independent of their orientation. However, Pascal did not specify the way in which forces are transmitted from point to point within the body of liquids. As I see it, Boyle's main contribution to the theoretical grasp of hydrostatics was to fill this gap, thereby completing a mechanical account of how hydrostatic phenomena come about.”(Chalmers, Robert Boyle's mechanical account of hydrostatics and pneumatics: fluidity, the spring of the air and their relationship to the concept of pressure, in Archive for History of Exact Sciences , September 2015, Vol. 69, No. 5 (2015), p. 444-445
"Hydrostatical Paradoxes is both a penetrating critique of Pascal's work on hydrostatics, full of acute observations upon Pascal's experimental method, and a presentation of a series of important and ingenious experiments upon fluid pressure" (DSB).
“Boyle points out, among other things, that since pressure in a liquid is transmitted equally in all directions, divers need not fear the greatest depths. To make quite certain that excessive water pressure was not harmful he placed young tadpoles, so tender that the seemed 'but organiz'd Gelly', into his container and caused a pressure equal to that of a cylinder of water 300 feet in height to be brought upon the fluid; the tadpoles seemed to shrink slightly, but swam as before and showed no evidence of injury when the pressure was released. The celebrated experiments 'that water may be made as well to depress a Body lighter then it self, as to buoy it up' are recorded in Paradox 8. The observation is still made in much the same fashion by all students in their 'practical' courses on physics."(Fulton).
Wing B3985; Fulton 72; Madan III, 2738