THE RINGED PLANET. 51 



that, whereas there is nothing inexplicable or even very surprising in 

 supposing that Saturnian cloud-layers, resulting from the action of 

 intense Saturnian heat, alter greatly at times in level, the observations 

 we have described become altogether inexplicable, and cannot, in fact, 

 be rejected, if we adopt the theory that Saturn resembles the earth on 

 which we live. 



It may be asked whether Jupiter, to which planet the same rea- 

 soning may be applied, has ever shown signs of similar changes. To 

 this it may first be replied, that we should not expect Jupiter to be 

 affected to the same degree, simply because the chief disturbing causes — 

 his satellites and the sun — are always nearly in the same level, owing 

 to the peculiarity in Jupiter's pose to which attention has already been 

 directed. But, secondly, such briefly-lasting changes as we might ex- 

 pect to detect have occasionally been suspected by observers of con- 

 siderable skill; and among others by the well-known Schrftter, of Lili- 

 enthal. Such changes have consisted, for the most part, merely in a 

 slight flattening of a part of Jupiter's outline. But on one occasion a 

 very remarkable phenomenon, only (but very readily) explicable in 

 this way, was witnessed by three practised observers — Admiral Smyth, 

 Prof. Pearson, and Sir T. Maclear — at three different stations. Ad- 

 miral Smyth thus describes what he saw : " On Thursday, June 26, 

 1828, the evening being extremely fine, I was watching the second 

 satellite of Jupiter as it gradually approached to transit Jupiter's disk. 

 It appeared in contact at about half-past ten, and for some minutes 

 remained on the edge of the disk, presenting an appearance not unlike 

 that of the lunar mountains coming into view during the moon's first 

 quarter, until it finally disappeared on the body of the planet. At 

 least twelve or thirteen minutes must have elapsed, when, accidentally 

 turning to Jupiter again, to my astonishment I perceived the same 

 satellite outside the dish ! It remained distinctly visible for at least 

 four minutes, and then suddenly vanished ! " For our own part, we 

 can conceive of no possible explanation of this remarkable phenomenon, 

 unless it be admitted that the change was in the apparent outline of 

 Jupiter. Of course, to suppose that even a cloud-layer rose or fell, in 

 a few minutes, several thousand miles (about 8,000, if the stated times 

 be correct), is as inadmissible as to suppose the solid crust of a globe 

 to undergo so vast a change of level ; but nothing of this sensational 

 description is required. All that would be necessary would be, that 

 an upper cloud-layer should for a few minutes be dissipated into vapor, 

 either by warm currents, or more probably by a temporary increase 

 of the heat supplied by Jupiter's fiery globe within the cloud-envelopes, 

 and that a few minutes later the clouds should form again by the 

 condensation of the vaporized matter. The changes in the aspect of 

 the Jovian belts are often sufficiently rapid to indicate the operation 

 of precisely such processes. 



Associated with such phenomena as we have mentioned is the evi- 



