OF AllTS AND SCIENCES. 305 



then appeared a very different object, but the change was only tem- 

 porary, as on the 23d it had resumed its former appearance. How- 

 ever, it is probable that some irreguhirity will be found on that date, 

 and a jumj) may be noticed. 



Between the 14th and 2Gth of September, 1877, the angular mark D 

 was not seen, although ten observations and drawings were made 

 during that interval. From calculation of the period of this mark, it 

 is found that it should have been on the disk on the 16th, 19th, and 23d, 

 at the time the observations were made. On the IGth, it should have 

 been l"* 1 6'" east of the centre ; on the 19th, 2"^ 9" west, and on the 23d, 

 1*^ 3™ east of it. If the marking had been visible, it certainly could 

 not have escaped my observation on the 1 6th and 23d, when it was less 

 than 40^ from the centre, especially as the sight was very good at the 

 time the observations were made. On the 19th, it might have passed 

 unnoticed, as it must have been quite close to the limb and consider- 

 ably foreshortened. 



At the time the disappearance of this mark occurred, great changes 

 were seen to be going on, in and about the equatorial belt, from which 

 the disappearance probably resulted. 



On the 26th, as already said, the mark was seen again, at the same 

 place, and with precisely the same characteristic form it had from the 

 beginning of my observations. 



Again, from Nov. 6 to Dec. 9 of the same year, the same 

 angular marking was not once seen, although the planet was ob- 

 served and drawn thirteen times during this interval. Calculation 

 showed that it should have been visible in November, on the 13th, 

 37™ east; on the loth, l*" 52"" east; on the 18th, 26" west; on 

 the 20th, l*" 9"" east; and on the 30th, 15"' west of the central mcr 

 ridian ; while in December it should also have been on the disk on 

 the 2d, 1'' 34"" east, and on the 3d, 2*' 19™ west of the centre. But 

 not the slightest traces of it were detected, although looked for ; not 

 even on the 13th, 18th, and 30th of November, when it should have 

 been close to the central meridian. 



On Nov. 13th, when this mark should have been near the centre, 

 it was found that, at the very place it should have occupied, the 

 southern margin of the equatorial belt was wavy, irregular, and some- 

 what swollen, but nothing looking like the familiar object so often 

 observed was visible. 



After Dec. 9, 1877, the observations were discontinued, Jupiter 

 being too near the Sun to be observed with advantage, and were 

 not regularly resumed after conjunction until Sept. 6, 1878. 



VOL. XVI. (n. s. viii.) 20 



