OTTO GUERICKE 6i 



whereupon a loud report resulted; whereas the simple open- 

 ing of a stop-cock caused them to fall apart of themselves. 

 The large pair, having a diameter of one ell, was calculated 

 by Guericke to require two teams of twenty-four horses. 

 These experiments were shown by Guericke in Regensburg 

 at the Reichstag in 1654, first to a small circle, and then by 

 request to the Emperor and the princes. The news of his 

 discovery then spread rapidly, and particularly the knowledge 

 and conviction of the magnitude of the atmospheric pressure, 

 if much had not, as is probable, already become known 

 already from Magdeburg. Guericke contributed to this by 

 handing over the apparatus he had brought with him to 

 some influential personalities who desired it. Part of it then 

 came to the university of Wiirzburg, and from there, and 

 later by Boyle in England, a printed account was published 

 of Guericke's original experiments, and also of some varia- 

 tions, whereby his priority appears to have been suppressed 

 to some extent.^ This caused Guericke himself to write a 

 book De Vacuo Spatio ('New Magdeburg Experiments on 

 Empty Space'); it was finished in 1663, and finally printed in 

 1672. 



Guericke also engaged in other investigations. He dis- 

 covered electrical repulsion; hitherto only attractive forces 

 had been known. For this purpose he made use, in place of 

 small pieces of resin excited by friction, of a large cast ball of 

 sulphur, which could be turned about an axis, whereby a 

 beginning was made of the later frictional electrical machine. 

 Guericke's original machine, an example of which was 

 early received by Leibniz, produced electric sparks for the 

 first time (1672), a fact reported by Leibniz in a letter to 

 Guericke. 



Guericke's old age was clouded by remarkable ingratitude 



^ A striking sign of this is found in Huygens' famous essay on Light 

 (1678), where Boyle is described as the inventor of the air-pump, though 

 Boyle himself mentions Guericke as the originator. 



