Some idea of the ordinary appearance of the planet may be gained from Fig. 25, which reproduces a sketch made with a small telescope on October 9, 1891. The first feature that strikes the eye on even the most casual glance is the polar compression. The outline of the disc is manifestly not circular but elliptical, and this is emphasized by the fact that nearly all the markings which are visible run parallel to one another in the direction of the longest diameter of the oval. A little attention will reveal these markings as a series of dark shadowy bands, of various breadths and various tones, which stretch from side to side of the disc, fading a little in intensity as they approach its margin, and giving the whole planet the appearance of being girdled by a number of cloudy belts. The belts may be seen with very low powers indeed, the presence of the more conspicuous ones having repeatedly been evident to the writer with the rudimentary telescope mentioned in Chapter II., consisting of a non-achromatic double convex lens of 1-1/2-inch aperture, and a single lens eye-piece giving a power of 36. Anything larger and more perfect than this will bring them out with clearness, and an achromatic of from 2 to 3 inches aperture will give views of the highest beauty and interest, and will even enable its possessor to detect some of the more prominent evidences of the changes which are constantly taking place. The number of belts visible varies very considerably. As many as thirty have sometimes been counted; but normally the number is much smaller than this. Speaking generally, two belts, one on either side of a bright equatorial zone, will be found to be conspicuous, while fainter rulings may be traced further north and south, and the dusky hoods which cover the poles will be almost as easily seen as the two main belts. It will further become apparent that this system of markings is characterized by great variety of colouring. In this respect no planet approaches Jupiter, and when seen under favourable circumstances and with a good instrument, preferably a reflector, some of the colour effects are most exquisite. Webb remarks: 'There is often "something rich and strange" in the colouring of the disc. Lord Rosse describes yellow, brick-red, bluish, and even full-blue markings; Hirst, a belt edged with crimson lake; Miss Hirst, a small sea-green patch near one of the poles.' The following notes of colour were made on December 26, 1905: The south equatorial belt distinct reddish-brown; the equatorial zone very pale yellow, almost white, with faint slaty-blue shades in the northern portion; the north polar regions a decided reddish-orange; while the south polar hood was of a much colder greyish tone. But the colours are subject to considerable change, and the variations of the two great equatorial belts appear, according to Stanley Williams, to be periodic, maxima and minima of redness being separated by a period of about twelve years, and the