890 Transactions. — Miscellaneous. 



The marked similarity between these two tables is most striking, and, as 

 in the first table, the greatest discrepancy is found between Krakatoa and 

 Mauritius, where the time is reckoned in so many hours, in which case an 

 hour or two makes a material difference in the diurnal velocity. 



At present I cannot find any station reporting the phenomenon between 

 Mauritius and Adelaide, but we may conclude that after it passed Mauritius it 

 crossed Africa, the South Atlantic, and South America, whence we may expect 

 to hear of it as there are many competent observers in that part of the world; 

 it then traversed the great South Pacific Ocean and North Australia, and, 

 after performing another such journey round the world, was seen at 

 Adelaide in South Australia about the 17th September. I conclude, as Mr. 

 Todd, the Government Astronomer there, says in his report to " Nature," 

 that it was visible during the last fortnight of September. We next hear 

 of it at the Cape of Good Hope on the 20th September. It again crossed 

 the South Atlantic and South America about the latitude of Buenos Ayres, 

 and a third time traversed the South Pacific, striking the coast of New 

 Zealand on the 25th September, the date of my first seeing it, on which 

 occasion the. western sky at sunset presented all the colours seen in the 

 pearl shell. Since then the western and eastern skies have presented those 

 beautiful crimson tints that have delighted and astonished the world, and 

 on many occasions have I seen it almost in the zenith two hours after sun- 

 set. During some evenings it has quite illuminated the western face of 

 buildings with a bright red glow, as from a fire, and on others it has been 

 very faint and sometimes not discernible, giving to my mind the idea of its 

 not being a continuous band, but a series of dust clouds with clear spaces 

 between. 



From an investigation of the two foregoing tables, it will be seen that 

 the mean diurnal velocity in the northern hemisphere was, during the first 

 revolution, about 2,162 miles, and during the second it increased to 2,192, 

 or 30 miles per diem extra. And the same increased velocity is observed hi 

 the southern hemisphere, where we find the approximate velocity during 

 the first two revolutions, viz., on its reaching Adelaide, to be 2,041, whereas 

 during the next revolution from Adelaide round to New Zealand it was 

 2,120 miles, or an increase of 80 miles a day. 



It will be further noticed that in the northern hemisphere the time 

 occupied in its first revolution was about 11 days, and the same rate is 

 observed during the next revolution and three-quarters — or, in other words, 

 within the tropics it encircled the world in 11 days. It is the same within 

 the southern tropics, where it took 21J days to reach Adelaide in its second 

 revolution ; but it performed the next revolution in about 9i days, reaching 

 New Zealand in 29J days after the eruption. Thus it performed two revo- 

 lutions and three-quarters (2f) in the northern hemisphere in 29f days, and 



