Designent AB , BC , CD , &c. pulsuum successivorum æquales distantias; ABC plagam motus pulsuum ab A versus B propagati; E , F , G puncta tria Physica Medii quiescentis, in recta AC ad æquales ab invicem distantias sita; Ee , Ff , Gg , spatia Page 365 æqualia perbrevia per quæ puncta illa motu reciproco singulis vibrationibus eunt & redeunt; ε, φ, γ loca quævis intermedia eorundem punctorum; & EF , FG lineolas Physicas seu Medii partes lineares punctis illis interjectas, & successive translatas in loca εφ, φγ & ef , fg . Rectæ Ee æqualis ducatur recta PS . Bisecetur eadem in O , centroque O & intervallo OP describatur circulus SIPi .