OTTO VON GUERICKE (1602-1686), an experimental philosopher, distinguished by his original discoveries of the properties of air, was born at Magdeburg, in Prussian Saxony, November 20, 1602. Having studied law at Leipsic, Helmstadt, and Jena, and mathematics, especially geometry and mechanics, at Leyden, he visited France and England, and, returning to Saxony, took up the profession of engineer-in-chief at Erfurt. In 1627 he was elected alderman of Magdeburg, and in 1646 mayor of that city, and a magistrate of Brandenburg. It was whilst holding these offices that Guericke devoted his leisure to scientific pursuits, especially in pneumatics. Incited by the discoveries of Galileo, Pascal, and Torricelli, he attempted the creation of a vacuum, a desideratum in science from before Aristotle. He began by experimenting with a pump on water placed in a barrel, but found that when the water was drawn off the air permeated the wood. He then took a globe of copper fitted with pump and stopcock, and discovered that he could pump out air as well as water. Thus Guericke became the inventor of the air-pump (1650). This important discovery was publicly explained before the emperor Ferdinand III. at the imperial diet which assembled at Ratisbon in 1651. Guericke at the same time illustrated in a simple but effective way the force of atmospheric pressure. Placing side by side two hollow hemispheres of copper, he exhausted the air from between them by means of pump and stopcock, and it is recorded that thirty horses, fifteen back to back, were unable to pull them asunder. The apparatus used on this occasion is still preserved in the imperial and royal library at Berlin. Guericke further demonstrated, by the aid of the air-pump, that in a vacuum all bodies fall equally fast, that animals cannot exist therein, and other phenomena. He also invented the air-balance, and the anemoscope, a species of weathercock. The discovery of the property of electro-repulsion is also attributed to him; and he made successful researches in astronomy, predicting the periodicity of the return of comets. In 1681 he gave up office, and retired to Hamburg, where ho died May 11, 1686.

His principal observations are given in his work, Experimenta nova, ut vacant, Magdeburgica de vacuo spatio (Amsterdam, 1672). He is also the author of a Geschichte der Belagerungmid Eroberung von Magdeburg. See Hoffmann, Otto von Guericke, Magdeburg, 1S74.