Abstract
Of the four annular nebulae known to the Herschels, only two are visible or easily visible in northern latitudes. One of these is the Ring nebula in Lyra, familiar to all observers with small telescopes. The other, in Cygnus, is small and faint, and hence has been very little studied. Many of the planetary nebulae are bounded by bright rings, or contain bright rings within an outer and fainter limit; but for various reasons these nebulae are usually placed in a separate class. In connection with a series of researches on the nebulae, now in progress with the Crossley reflector, the two ring nebulae above mentioned were photographed a number of times during the past summer. In what follows I give briefly the substance of a paper which was read before the conference of astronomers at the Yerkes
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