84 SOME NOTES ON JUPITEE DUEING HIS OPPOSITION OP 1876. 



poles, which, by their diminishing during the Martial summer 

 and increasing in his winter, convince us to be ice. Still, with 

 the possessors of small telescopes. Mars is not I think a prime 

 favourite. The period during which we can advantageously 

 observe him is short — a few weeks before and after opposition ; 

 after which he rapidly recedes from us, and his orbit carries him 

 so far off that his disk dwindles down to most uninteresting pro- 

 portions, and his markings are lost to all small glasses. Besides, 

 even at opposition it requires a really good and powerful telescope 

 to do satisfactory work on Mars. In the best drawings that I 

 have seen there is a strange haziness about details, and different 

 observers appear to me to disagree most woefully in their 

 delineations. 



Saturn has for many I must confess, including myself, a large 

 number of attractions. I cannot well dwell at present on the 

 subject, as it is foreign to the object of this paper ; and even a 

 short account of his wondrous details would require a paper by 

 itself. Still, confining myself to the premise that I am speaking 

 almost exclusively of amateurs, and as such possessing only mode- 

 rately powerful telescopes, Saturn, from his enormous distance, 

 presents difficulties which Jupiter does not ; his ring, with Ball's 

 division, perhaps a belt, and three or four of his satellites, are as 

 much as most small telescopes show ; what has been discovered 

 besides are details of great delicacy, and some points connected 

 with Saturn remain tests for the largest and most perfect tele- 

 scopes of the present day. 



So there remain but Uranus and Neptune ; and I wonder, out 

 of all that have ever lived on the earth, how many have ever seen 

 these at all. Indeed, a very few. They might, I fancy, be 

 counted on your fingers ; and, should an ordinary observer get 

 one of these outside wanderers by accident into the field of his 

 glass, he would probably pass them by as fixed stars. 



We return therefore to the subject which brings me before 

 you — Jupiter. How readily his noble disk shows out in even the 

 smallest glass, many of you — and I suppose that there are few 

 here who at some time or other have not seen him through a 

 telescope — are well aware. An aperture of even a couple of 

 inches will show some signs of streaks on his disk, and his moons 

 quite brilliantly. As we increase our aperture and power, more 

 and more detail comes into view, the belts assume definite form, 

 traces of colour are seen, and his four satellites turn out very 

 respectable-sized disks of their own. Their shadows, their occul- 

 tations, and their eclipses present a scene of ever-varying interest 

 and beauty ; and this, W' ith the extreme facility with which it can 

 be seen in even what are now considered small telescopes, makes 

 Jupiter, as I said before, a most interesting object for all 

 amateur observers. 



