The shadow of the planet on the rings may be well seen with a good 2-inch telescope, which will also show Ball's division in the rings. The shadow of the rings on the planet is a somewhat more difficult feature. The shadow of the planet on the rings is best seen when the rings are well open and the planet is in or near quadrature. It is to be looked for to the left of the ball (in an inverting telescope) at quadrature preceding opposition, and to the right at quadrature following opposition. Saturn is more likely to be studied at the latter than at the former quadrature, as in quadrature preceding opposition he is a morning star. The shadow of the rings on the planet is best seen when the rings are but moderately open, and Saturn is in or near quadrature. When the shadow lies outside the rings it is best seen, as the dark ring takes off from the sharpness of the contrast when the shadow lies within the ring. It would take more space than I can spare here to show how it is to be determined (independently) whether the shadow lies within or without the ring. But the 'Nautical Almanac' gives the means of determining this point. When, in the table for assigning the appearance of the rings, l is less than l' the shadow lies outside the ring, when l is greater than l' the shadow lies within the ring.
Uranus is just visible to the naked eye when he is in opposition, and his place accurately known. But he presents no phenomena of interest. I have seen him under powers which made his disc nearly equal to that of the moon, yet could see nothing but a faint bluish disc.
Neptune also is easily found if his place be accurately noted on a map, and a good finder used. We have only to turn the telescope to a few stars seen in the finder nearly in the place marked in our map, and presently we shall recognise the one we want by the peculiarity of its light. What is the lowest power which will exhibit Neptune as a disc I do not know, but I am certain no observer can mistake him for a fixed star with a 2-inch aperture and a few minutes' patient scrutiny in favourable weather.
