192 GERARDI REGNER! FOCKENS 



bene aulem omnia coordinasset unus Bradicius, hiiic principi viro darenl fidem aflir» 

 manti , parallaxin aut nullam iinquam , aut iion nisi virium nisu longe maximo aliquam 

 esse reperiundam. 



Detecla scilicet aberralione luculenler ille ostendit, omnes has varialiones fixariim , quas 

 observassent Picard, Flamstead, Römer, Cassini, Horrebow, Manfredi, 

 sed aut non omnino aul male explicassent , unico Iribuendas esse effeclui aberrationis, 

 aut , si quid eliam insuper ad observationum congruentiam desideretur , hoc ncquaquam 

 parallaxi , sed causae cuidam non semper latiturae adscribendum esse. Hanc causam 

 autem ajebat se jjersecuturum , et, ni spes fallalur, brevi eliam asseculurum esse. 



Quapropler , dum reliqui omues requiescuut , nos interim ad hujus soporis auclorem 

 redeamus. 



§ 17. 



Ad Bradl ei um itaqne incomparabilem reverlor. Quirlqiiid scribal , quidquid agat,' 

 ubivis nescio quid ingeniosum translucet et spirat singulare. Ergo perlustremus alteram 

 eliam epistolam , qua continetur observationum anleriorum continualio ('). 



« The great exaclness, wilh which inslruments are now constructed, halb enabled 

 « the astronomers of the present age to discover several changes in the positions of the 

 « heavenly bodies; which, by reason of their smallness, had escaped the notice of 

 « Iheir predecessors. And altho' the causes of such motions have always subsisled , yet 

 « philosophers had not so fully consider'd , what the elTects of Ihose known causes 

 « would be , as to demonslrale a priori the phaenomeiia they might produce; so that 

 « theory itself is here , as well as in many other cases, indebted to practice, for the 

 (c discovery of some of its most elegant deductions. This poinls out to us the great 

 « advantage of cultivating this, as well as every olher branch of natural knowledge , by 

 « a regulär series of observations and experiments. " 



« The progress of astronomy indeed has always been found to have so great a de- 

 « pendenre upon accurate observations, that, tili such were made, it advanced but 

 X slowly. For the first considerable improvemenls thut it received, in point of theory , 



<i we- 



C) Phil. Trans. Jannar. 1748. T. s'ive Tom. LXIX. (XLV) n''. 485. p. r. Titnlus est: » A htter 

 « 10 the Right Iwnourable George Earl q/'Maccleslield, concerning an apparent Motion obseroed 

 « in some 0/ tlie ßxed stai s , by James Cradley , D. D. Astronomer Royal , and F. R. S. Caput 

 est.- »Read at a meUing of the Royal Society, Febr. l(\^ •74/." Caliaalcni;«! Grtenwich Du, it , 

 ' 1747." 



