I90 IN STARRY REALMS. 



a telescope of sufficient power, would no doubt generally 

 find a large part of our globe obscured by suspended 

 masses of vapour. He would also certainly see some 

 traces of those belts of cloud, parallel to the equator, 

 which inark the trade wind zones. And he would be 

 struck with the instability and fickle character of the 

 cloudy screen which in the course of a few hours would 

 reveal or obscure whole kingdoms or oceans. The obser- 

 vations of the clouds alone would make the telescopic 

 scrutiny of our world from some distant world a singu- 

 larly interesting and instructive research. There are 

 perhaps some regions on the globe which would be almost 

 continuously quite free from cloud, and these the Jovian 

 astronomer could draw without any special choice of 

 opportunities. But to trace the majority of the outlines 

 of the continents and the oceans would be an arduous, 

 if even a possible, task ; at the least it would require the 

 patient astronomer to wait until openings in the clouds 

 enabled the outlines of the coasts to be clearly appre- 

 hended. But on Jupiter the clouds are so massive, that 

 no amount of patience ever enables us to see through 

 them ; the chance is never given to us. We are there- 

 fore compelled to suppose that the heat by which the 

 vapours to form clouds are manufactured, must be much 

 more abundant and intense than it is on our globe. The 

 heat that provides moisture for our atmosphere is obtained 

 from the sun. The warm rays beating down on our vast 

 oceans create great volumes of water vapour, which ascend 

 thousands of feet, and are then borne by winds to other 

 less genial climes, where chills reduce the transparent 

 water vapour to that opaque material of visible steam or 



