270 NOVUM ORGANVM 



will place the generally useful instances. They are such 

 as relate to various points, and frequently occur, sparing 

 by that means considerable labor and new trials. The 

 proper place for treating of instruments and contrivances, 

 will be that in which we speak of the application to practice, 

 and the methods of experiment. All that has hitherto been 

 ascertained, and made use of, will be described in the par 

 ticular history of each art. At present, we will subjoin a 

 few general examples of the instances in question. 



Man acts, then, upon natural bodies (besides merely 

 bringing them together or removing them) by seven prin 

 cipal methods: 1, by the exclusion of all that impedes and 

 disturbs; 2, by cfompression, extension, agitation, and the 

 like; 3, by heat and cold; 4, by detention in a suitable 

 place; 5, by checking or directing motion; 6, by peculiar 

 harmonies; 7, by a seasonable and proper alternation, series, 

 and succession of all these, or, at least, of some of them. 



1. With regard to the first common air, which is al 

 ways at hand, and forces its admission, as also the rays of 

 the heavenly bodies, create much disturbance. Whatever, 

 therefore, tends to exclude them may well be considered as 

 generally useful. The substance and thickness of vessels 

 in which bodies are placed when prepared for operations 

 may be referred to this head. So also may the accurate 

 methods of closing vessels by consolidation, or the lutum 

 sapiential, as the chemists call it. The exclusion of air by 

 means of liquids at the extremity is also very useful, as 

 when they pour oil on wine, or the juices of herbs, which 

 by spreading itself upon the top like a cover, preserves 

 them uninjured from the air. Powders, also, are service 

 able, for although they contain air mixed up in them, yet 

 they ward off the power of the mass of circumambient air, 



