SIMON STEVIN 23 



importance in making clear to us the concept of work. We 

 see that the amount of work, as measured by the product of 

 force into distance, remains unchanged in the case of all 

 machines. 



Also in the case of the equilibrium of liquids (hydrostatics), 

 we are acquainted with investigations by Stevin of funda- 

 mental importance, and dealing with practically all import- 

 ant points. He deduces the laws of distribution of pressure 

 in liquid, and the pressure at the bottom of the vessels, 

 whereby he again starts from the idea of the impossibility 

 of perpetual motion, and adds a further rule, according to 

 which the equilibrium in a liquid is not disturbed, when 

 a part of it becomes solid (without change of volume). He 

 thus arrives at the important fact, which appears a paradox, 

 that the pressure at the bottom of a liquid is independent 

 of the section and shape of the liquid column producing it, 

 the height and specific gravity of the liquid being the sole 

 factors determining the pressure. He tested and proved this 

 law by means of a pair of scales, one pan being the bottom 

 of a vessel of liquid, to which he could give different shapes. 

 In his consideration of liquids in communicating tubes, and 

 of floating bodies, he again has points of contact with Archi- 

 medes and Leonardo, but he goes beyond the Archimedean 

 principle, inasmuch as he does not merely determine the 

 magnitude and position, but also and for the first time, the 

 point of application of the buoyancy, the 'metacentre,' which 

 remains fixed, even when the floating body is moved within 

 certain limits. He made use of this new piece of knowledge 

 in the construction of ships. 



Stevin also introduced calculations by means of decimals, 

 but at the time these did not find further adherents. The 

 fact that he studied not only Archimedes, but as was usual 

 at the time, Aristotle, is shown by his experiments on the 

 fall of bodies of different weight, which, in opposition to 

 Aristotle, he found to fall at equal speed. He says in a work 



