upennmanuscripts:smithsonianlibraries:Time marches on….welcome Autumn (or Spring) from ev
upennmanuscripts: smithsonianlibraries: Time marches on….welcome Autumn (or Spring) from everyone in the Northern (or Southern) Hemisphere! Original image from Otto von Guericke’s Experimenta nova (ut vocantur) Magdeburgica de vacuo spatio Though the first part of his Experimenta is dedicated to explaining cosmic systems, it is more well known for the later sections where he describes the creation of a vacuum between two spheres and a device that produces static electricity by generating friction against a moving ball of sulfur. Apropos of volvelles… -- source link