414 METHODrS OBSERVJNDl 



chius qnidcni ad hoc diio fii:! micromentm duosqiie obfer- 

 vatores rcquirit , quornm altcr dillantinm a fe inniccm 

 cornunm phalcos , altcr phafui ccliplijos , (cu dilhuitiam 

 maximam limborum dilci obli;nrantis dilciquc cclip(:uKis 

 codcm momcnto tcmporis oblernarc dcbct : Scd quia ob« 

 feruatores non cadcm dcxtcrinnc rcm expcdicndi pollent , 

 punclaquc oblcruanda alia f;icilins dilhcilius alia pcr fe 

 obfcruari poirunt , indc fit , vt dum vnus cornm cochleas 

 micromctri ad puinfla lua probc dircxit , altcr dirigit ad- 

 huc , et fi altcr bcnc dircxerit , prior itcrum dirigcic dc- 

 bct , ct fic porro ^ punfta cnim illa , quorum dillanriam 

 mcnliirant , in icftu oculi clocis fuis cxcunt , Ibtimqne ali- 

 tcr tam intcr fe , qnam rcfpcdu cochlcarum ponuntur : 

 adco vt maxime difhcile fit , mnltas vcl accnratas id ge- 

 nus obfcniationcs opc micromctri huius obtincrc , pnie- 

 fertim autcm in pcicgrinatiduibus , vbi ncc duo obfcrna- 

 torcs bcnc excrcitati , ncc locus ad oblciu.uioncs a duo- 

 bns obfcruatoribus inflitucndas commodus ficilc adcffc gotcfl. 

 Ad Hirii micromctron methodumquc pcr iilud obfcruandi 

 a Rortio dclcriptam quod attinct , in illa vnicui quidcm 

 oblcruator ad oblcruationcm hanc infiitucndam rcquiritnr, 

 fed cui multa , caquc maximc diihcilia ncgotia fimul cx- 

 pcdicnda funt : dcbct cnim is , dirigcndo rcpctitis vicibus 

 capillum aliqucm micromctri imniobiicm ad limbnm altc- 

 rutrius difci in fitu capilli ad cornua phafcos par.illclo , 

 f()llicitc obfcruarc tcmporis momcntum , qnando altcrius 

 difci limbus altcrnm cnpillum immobilcm fimul cnm prio- 

 ri rtiingit , codem(]nc momcnto , (]Uo hoc accidit , diri- 

 gcre tcnctnr capillum micromcrri mobilcm ad cornua pha- 

 feos , vt cadcm fimul cum prioribus cxadc contmgat : id 



quod 



