Steam digester Torricelli and further developed by German scientist Otto von Guericke with his Magdeburg hemispheres. Guerike's demonstration was documented by Gaspar Schott, in a book that was read by Robert Boyle. Boyle and his assistant Robert Hooke improved Guericke's air pump design and built their own. From this, through various experiments, they formulated what is called Boyle's law, which states that the volume of a body of an ideal gas is inversely proportional to its pressure. Soon the ideal gas law was formulated. Based on these concepts in 1679 a Boyle's associate, named Denis Papin, built a "bone digester", which is
Pressure vessel pressure vessels are designed to have a thickness proportional to the radius of tank and the pressure of the tank and inversely proportional to the maximum allowed normal stress of the particular material used in the walls of the container. Because (for a given pressure) the thickness of the walls scales with the radius of the tank, the mass of a tank (which scales as the length times radius times thickness of the wall for a cylindrical tank) scales with the volume of the gas held (which scales as length times radius squared). The exact formula varies with the tank