OTTO VON GUERICKE. 391 



edge, based on physical experimenting, gave new basis for 

 one or the other. Therefore when a man had made novel 

 discoveries, instead of contenting himself with stating 

 simply what he had done and how he had done it, and 

 leaving other people to make and find useful applications 

 of the new-found information, he was far more likely to 

 begin his dissertation either with a new cosmical hypothe- 

 sis or a re-statement of his favorite old one, and then to 

 adduce the discoveries as establishing the new notion or 

 as affording additional proof to the preferred doctrine. 

 The suppression, by the way, of this discursiveness, as 

 broad as the universe itself, and the limitation of scien- 

 tific treatises to matters strictly germane and relevant to 

 their subjects, is one of the great achievements of the 

 Royal Society and of the various philosophical bodies 

 modeled after it. 



Consequently, as might be expected, when von Guericke 

 gave the results of his pneumatic and electrical experi- 

 ments to the world, he did it in a treatise on Vacuous 

 Space "in quo totum Mundi Systemi consistit." 1 His 

 first book deals with the universe generally, and his sec- 

 ond with interstellar space. His own discoveries occupy 

 the third and fourth books, and then he gets back to vast 

 conceptions again, and, in successive divisions of his work, 

 considers the 'earth and moon, comets (whereof it may be 

 noted in passing he first pointed out the periodicity), the 

 planets and the fixed stars. We need not here occupy 

 ourselves with his astronomical or cosmical notions, and 

 the detailed history of his beautiful discoveries in pneu- 

 matics belongs to a different field in physics from that in 

 which we are now wandering. Hence the matters which 

 interest us, and those which astonished Monconys more 

 than two centuries ago, are also set forth in the book, 

 wherein are treated "the mundane virtues and other things 

 thereupon depending." 



Guericke; Experimenta Nova (ut vocantur) Magdeburgica de 

 Vacuo Spatio. Amsterdam, 1672. 



