taken at the Loivell Observatory. 495 



3. Turning now to the features themselves, we note that 

 the great red spot, as a spot, practically no longer exists — it 

 is now only faintly suffused with rose — but what was its 

 oval cradle is well defined in the photographs, shown much 

 as it has shown for the last thirty years. In fact in this 

 connexion it is interesting to note that this cradle proves to 

 be very much older than most people think. Long before 

 the red spot made its sensational appearance the cradle it 

 was to occupy was there. It is distinctly traceable in the 

 drawings of Sir William Huggins made in 1859-1860, 

 which he kindly sent me. My eye detected it the moment I 

 examined them. Here then we have evidence of a feature 

 which in its general outline has been stable and persistent 

 for fifty years, a marvellous length of time for a cloud form 

 as wfi know such things to continue to exist. This alone 

 would suffice to demonstrate that Jupiter's meteorologic 

 conditions owe nothing to the Sun. That this cradle then 

 became the centre of a vast ruddy mass, which after a time 

 disappeared to leave it in its former condition, indicated it 

 as the seat of some violent outburst from below, over which 

 the cloud veil, rent at the height of the explosion, settled 

 down again, covering the furnace from sight. That the 

 feature is so permanent hints at a certain plasticity as op- 

 posed to what we call gaseous in the constitution, and likens 

 it to those permanent seats of disturbance with whose vents 

 we are familiar on Earth. A volcano in embryo is what its 

 behaviour points it out to be. It probably forms a con- 

 necting link between volcanoes on the one hand and sun- 

 spots on the other. 



4. Perhaps the most interesting feature of the photographs 

 is their exhibition of the wisps lacing the equatorial belt. 

 These wisps were first detected and studied, I believe, by 

 Mr. Scriven Bolton, who communicated them here through 

 Prof. Turner. They were then visually observed at Flag- 

 staff, and many drawings made of them. Lastly, they 

 appeared in the photographs, being well shown in the prints. 

 They are very curious markings, being shreds or filaments of 

 a dusky character traversing transversely the bright equa- 

 torial belt. They proceed always from black spots of a 

 triangular shape set on the edge of the north or south 

 tropical dark belts as the case may be. They join such to 

 one another and to the medial dark line which with more or 

 less interruption threads the planet's equator. Their course 

 is usually inclined some forty-five degrees to the dark belts ; 

 but sometimes they go straight across. When tilted they 

 are as often right-handed as left-handed. They are widest 



