length of time. During almost all of its last apparition the 

 general appearance was that of a series of beautiful festoons, 

 sometimes depending from the northern dark belt, but usually 

 throwing out pillars to the southern and more conspicuous of 

 the two. The interior of these festoons was generally beauti- 

 fully white by contrast with the darker matter forming their 

 substance, and sometimes, under not very favourable atmos- 

 pheric conditions, would appear like brilliant white spots. I 

 think it is quite possible that this has given rise to a degree of 

 confusion with some astronomers in the northern hemisphere 

 in respect to this part of Jupiter's surface, which will be re- 

 ferred to presently. Underneath a remarkable hollow in the 

 south dark belt is the most striking feature on the whole planet 

 — the great red spot. Spot is hardly an appropriate name for 

 a space in which the whole of Australia would be lost, but it 

 is the name that happens to be attached thereto. It is just 

 possible that this spot was observed by Cassini in 1665 ; at all 

 events, a famous spot was observed in that year by this illus- 

 trious astronomer. The next notice of it is in 1792, when 

 Schroeter was observing an occultation of the planet by the 

 moon on April 7. The most remarkable phenomena noticed were 

 two nebulous undefined spots, perceptibly darker than the 

 principal belt; and a still more remarkable spot is represented 

 by Schroeter in the southern hemisphere of the planet, circular, 

 bright in the centre, and with a dusky shading all round. A 

 similar spot was also observed in 1786 and 1787. In 1868 Mr. 

 Denning records on the south belt a dark spot; of elliptical 

 form. This may have been the precursor of the great southern 

 ellipse first observed by Mr. Gledhill on November 14, 1869. 

 This ellipse was situated in about the same latitude as the 

 great red spot at present is, and is very likely the same object. 

 In fact, a sketch made on January 23, 1870, reveals a most 

 striking similarity to the present appearance of the planet in 

 almost every respect. The first certain record we have of the 

 appearance of the great red spot is from some observations 

 made at the Morrison Observatory by Professor C. W. Pritchett 

 in July, 1878. He says: — "On July 9 Jupiter was again 

 examined from llh. to 12h. 5m., Gl. M. T. I was surprised at 

 the extraordinary changes which had occurred both in the spots 

 themselves and in the contiguous parts of the belts. Two spots 

 still showed, but much enlarged, and with irregular outlines. 

 Their position, however, was very different from the position 

 noted on July 6. The place of one was a little west of the 

 most easterly one seen on July 6, and near the inner edge of 

 the northern equatorial belt; but the other had changed to the 

 south side of the southern equatorial belt, and far eastward, and 

 seemed to be rapidly breaking up. What was more remarkable 



