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PROPO SITI0 III. PROBLEMA. 
J \ 
In fyftemate duorurn planetarum in orbitis circulari- 
bus circa Solem revolventium, motum nodorum 
orbits planets interioris, quatenus ex vi planets 
exterioris oritur, inveftigare. 
Per motum nodorum hie intelligendus eft motus 
interfedlionis plani orbis planets interioris cum piano 
orbis planets exterioris fpedlato ut immoto. Itaque 
efto Sol in S (Fig. 5.) et centro S atque radio SC^de- 
feribantur in fuperfkie fphsrs duo circuli QN, PN, 
l'efe interfecantes in N, quorum prior Q^N defignet 
fttum plani orbis planets interioris et pofterior 
P N fttum plani orbis planets exterioris, cujus locus 
fit in re&a SP produdta. Eodem centro S et radio 
SP deferibatur circulus PK, cujus planum fit piano 
SQN 
