Font enelle, of the Vfefulnefs 



None but Societies, of thofe too countenanc'd 

 and encourag'd by the Prince, can fuccefsfolly 

 make and prepare this Collection of Materials. 

 All the Learning, Care, Life and Wealth of 

 one Private Man can never anfwer this Defign. 

 There are too many different Experiments to 

 be made, which are to be too much vary'd, and 

 a Song time profecuted with the fame Temper 

 and Mind. The Caufeof the leaft Effect is fa 

 wrap'd up, that unlefs you very carefully open 

 all the various Foldings, you cannot come 

 at it. 



Hitherto the Academy of Sciences hath con- 

 fider'd Nature but by parcels : They have fix'd 

 upon no general Syftem, for fear of falling into 

 the inconveniency of hafty Syftems, which are 

 very grateful to the impatience of Humane Un- 

 derftanding j and being once fettled, are Obfta- 

 cles to what Truths are afterwards difcover'd. 

 This day we are fure of a Fact, to morrow we 

 (hall be fare of another that hath no relation 

 with the former. However fame Conjectures 

 are ventur'd at upon Caufes ; but they are only 

 Conjectures. So that this Colleclion, which 

 the Academy gives to the Publick, is compos'd 

 of faparate Fragments, independant of one ano« 

 ther j whereof every one who is the Author, 

 warrants the Facts and Experiments ; and whofa 

 Arguments are approv'd by the Academy, but 

 with Reftrictions becoming Wife and Wary 

 Scepticks. 



Time perhaps will come, when thefe fcat- 

 ter'd Fragments fhall be united into one regu- 

 lar Body; and if they be fach as they are 

 wifti'd, they may of themfelves Unite* A great 

 many Truths, when their Numbers is confide* 



rable, 



