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.