A system of natural philosophy, designed for the use of schools and academies (1845)
Moffat, J[ohn] M. [from old catalog] · Philadelphia, E. C. Biddle · leaf 374
d,and B /, as if theyissued from a focus H in front of the lens beyond O. When G,the point of convergence, coincides with O, the rays will be pa-rallel after refraction; and when the point G falls within the pointO, the refracted rays will converge to a focus on the same side ofthe lens with G, but… … What directions will rays generally follow after refraction by a con-cave lens ? Where is the principal focus of such a lens conceived to be situated ?- In what manner will the principal focal distance be ascertained ? How will converging rays be refracted, which, before refraction, con-verge to a…
Physics
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![An illustration from Sidereus nuncius : magna, longeque admirabilia spectacula pandens, suspiciendaque proponens vnicuique, praesertim verò philosophis, atq[ue] astronomis, quae à Galileo Galileo ... perspicilli nuper à se reperti beneficio sunt obseruata in lunae facie, fixis innumeris, lacteo circulo, stellis nebulosis, apprime verò in quatuor planetis circa Iouis stellam disparibus interuallis, atque periodis, celeritate mirabili circumuolutis; quos, nemini in hanc vsque diem cognitos, nouissimè author depraehendit primus; atque Medicea sidera nuncupandos decreuit (1610)](https://img.insideoutlibrary.com/img/200/ia-sidereusnunciusm00gali-18-4.webp)
