88 ESSAYS AND OBSERVATIONS 



from whence all efFedts in Nature arc deri^ 

 ved J when, in truth, he was unable to de- 

 duce from them the fimpleft cafes of coili- 

 fion. Many in this age, who write and fpe- 

 culate on phyfical fubjeds, feem to fall into 

 a like error ; while they employ their whole 

 ftudy in endeavouring to reconcile all pha^ 

 nomena with the new principles difcovered by 

 Sir Ifaac Newton : and, when they find, to 

 their mortification, that this will not always 

 fucceed ; phenomena mufl be difguiled, and 

 Nature tortured, to hide their ignorance. 

 From the lazy method of philofophizing in 

 the clofet, among books and diagrams, there 

 never arofe, there never will arife, any dif- 

 covery of confequence : Great inventors u- 

 fually under (land the extent of their own 

 principles too well, to leave much of the ap- 

 plication of them to others. 



The difcovery of the different refrangibi-* 

 lity of the rays, was an ineftimable addition 

 to natural knowledge ; as it ferves, at once, 

 for explaining innumerable phcenomena in Na- 

 ture which flow from it as immediate and 

 neceffary confequences : and, if it fhall be 

 demonftrated by the obfervation propofed in 

 N° 49. that the differently-coloured rays 



really 



