Ritchey, nebula round Nova Persei, [401];
photographs of nebulæ, [432]
Ritter, development of stars, [375]
Roberts, A. W., southern variables, [392]
Roberts, Isaac, search for ultra-Neptunian planet, [306];
photographs of Orion nebula, [408]
of Andromeda nebula, [409]
of the Pleiades, [411]
Roberval, structure of Saturn's rings, [299]
Robinson, reflectors and refractors, [431]
Roche, inner limit of satellite-formation, [301];
modification of nebular hypothesis, [321]
Römer, star places,[ 10];
invention of equatoreal and transit instrument, [120]
of altazimuth, [121]
velocity of light, [231]
satellite transit on Jupiter, [291]
Rosenberger, return of Halley's comet, [101]
Rosetti, temperature of the sun, [219]