96 SOME 25-OTES ON JUPITEE DrEING HIS OPPOSITION OF 1876. 



A brief change might be readily explained as due to such causes 

 as affect our own air. Large regions of the Earth are at one 

 time cloud-covered, and at another time free from clouds ; such 

 regions seen from Yenus or Mercury would at one time appear 

 white, and at another would show whatever colour the actual 

 surface of the ground might possess when viewed as a whole. 

 But it seems altogether impossible to explain in this way a 

 change or series of changes occupying many years, as in the case 

 of the coloui' changes of Jupiter's belt. It is one of the strongest 

 arguments agaiQst the theory that solar action has to do with 

 these changes, that any changes produced by solar influence 

 would be so slight as to be in effect scarcely perceptible. If, 

 however, Jupiter's whole mass be in a state of intense heat, we 

 can understand any changes, however amazing ; we can see that 

 enormous quantities of vapour must be continually generated in 

 the lower regions, to be condensed in the upper ; and although we 

 may not be able to indicate the precise reason why at one time 

 the mid-zone or any other belt on Jupiter's surface should 

 exhibit the whiteness which would seem to indicate the presence 

 of clouds, and at another should show a colouring which appears 

 to indicate that the glowing mass below is partly disclosed, we 

 remember that the difficult}- corresponds in character to that 

 which is presented by the phenomena of solar spots. The most 

 probable hypothesis appears to be that the ruddy glow of Jupiter's 

 equatorial belt is due to the inherent light of glowing matter 

 underneath his deep and cloud-ladenatmosphere. 



This seems, as I said before, to be about the best theory yet 

 advanced in this matter ; but the human mind craves for some- 

 thing more substantial than mere supposition. And the questions 

 that naturally arise when concluding a series of observations like 

 the present are — Shall we ever in our present state hnoio any 

 more of the real nature and purpose of these magnificent orbs ; 

 shall this opposition of 1876 ever furnish a link in the chain that 

 is to lift the veil that hangs on all outside ; or are we but 

 accumulating a pile of facts, a mass of observations, which, like 

 the scattered necklace-beads, want the connecting string to form 

 them into one harmonious whole ? Are we, like the benighted 

 wanderer in the desert, travelling in a circle, to find ourselves 

 back at the point whence we started ? Is it ever with the telescope 

 and spectroscope to be " thus far and no farther" ? 



Ko ! I cannot but believe that the time will come, though it be 

 generations hence, when the fruit of many years of patient watch- 

 ing shall be, — the reversal of the complex pattern on the under 

 side" of which we have so long toiled, tracing with anxious care its 

 numberless perplexing threads, and then the design of the Creator 

 in the solar system will stand revealed in all its symmetry and 

 beauty. 



