The planet should be frequently examined during every opposition with the highest powers that are consistent with a perfectly distinct image; and the observer should closely scan the various parts of the disk, with an endeavour to trace spots, breaks, or other irregularities in the belts. Certain inequalities of tone have been occasionally apparent in past years, and they will doubtless reappear. The recovery of these features will form a welcome addition to our knowledge, and, if adequately observed, will enable the rotation-period of the planet to be rediscussed. In an enquiry of this kind many observations are needful, and the longer the interval over which they extend the more accurate the results derived from them are likely to be. If a broken belt should appear on Saturn, the time of its passing the planet’s central meridian should be recorded, either by measurement or careful estimation, and an ephemeris computed based on a rotation-period of 10-1/4^h, which is equal to a daily rate of nearly 843°. Then it should be carefully looked for on subsequent evenings at the times given in the ephemeris, and on every occasion when re-observed its time of transit should be noted as at first. As long as the break continues visible, so long ought it to be kept in view and the times of its central passages tabulated. It would be advisable in such a case to secure cooperation from other observers, as more numerous observations would be sure to accrue, so that, on the appearance of a marking such as that alluded to, the discoverer will do well to announce it immediately to other amateurs who are engaged upon planetary work and most likely to assist him. A white or dark spot, or any condensation on the belts, would of course serve the same purpose as a broken belt. The nature of the object is not necessarily to be considered, the main requirement being that it is one of which the longitude admits of determination. Markings on the belts, if they are ever discernible, must be watched with corresponding assiduity for traces of motion; and if such motion should betray itself, the object of the observer will be to ascertain its rate.