86 SOME NOTES 0:S JUPITER DURINa HIS 0PP0SITI02T OP 1876. 



drawings I have been aided by a most efficient driving- clock, 

 which keeping the object in the centre of the field of the telescope 

 leaves both the hands free for other work, the advantage of which 

 can only be appreciated by those who, in their attempts to deli- 

 neate the heavenly bodies, are obliged to have one hand constantly 

 employed in screwing away at a handle, to follow the motion of 

 the object as it rapidly flits through the field. 



The construction also of the Newtonian reflector is peculiarly 

 adapted for drawing purposes, as the erect position of the observer 

 is easy and natural ; and with your desk at your elbow, you can 

 rapidly transfer your eyes from the telescope to the paper before 

 you. 



On the w^hole I must say that the weather we have been 

 favoured with since I commenced these observations has not been 

 eminently adapted to telescope-work. "We have had a rather 

 more than fair allowance of cloudy evenings, and many of the 

 most brilliant nights have been utterly worthless, from their 

 blurred and tremulous definition ; moreover, there appears to be 

 at all times present a considerable amount of vapour in the higher 

 regions of the atmosphere, so that even when definition is most 

 steady, you have a consciousness that you are looking^ at the 

 object under a veil, the field of the telescope not appearing per- 

 fectly dark as it should do. This is more especially tantalizing, 

 as even on some of the most inferior nights you get moments — 

 they only last for a second — of most startling definition, when 

 the planet seoDis to be brought to within half its usual distance, 

 and details start out before you so numerous, and so complex, 

 that the eye in that evanescent moment totally fails to grasp 

 them, and the next second they are gone, and you are left with a 

 dazed impression that you have seen something that would tax 

 the skill of a far more accomplished artist than yourself to do the 

 slightest justice to. I have at times — but only, as I said before, 

 for a second — seen the whole of the disk of Jupiter covered with 

 fine lines ; even the white belts, which ordinarily present not a 

 trace of marking, are scored by them all over ; and the darker 

 equatorial zone appears a mass of flocculent, cloudy matter ; but 

 to attempt to put this on paper during the fleeting moment it is 

 visible is an impossibility, 



- "While on this part of my subject I may mention that one of 

 the first things that attracted my attention, when looking up the 

 observations recorded of Jupiter during the last ten or fifteen 

 years, was the remarkable paucity, I might almost say the entire 

 absence, of any reliable or well-executed drawing of the planet. 

 I must, of course, confine this assertion to any published draw- 

 ings for there may be, and probably are, many fine delineations 

 in the hands of those who drew them, which will never see the 

 light ; but speaking of those pictures which have been given to 



