384 Transactions. — Miscellaneous. 



of the sun-glows in different places are so important ; e.g., we could tell the 

 rate of progress of the dust to us in Nelson pretty well if we knew for 

 certain when the glows first appeared in Port Darwin, Brisbane, Sydney, 

 and Nelson. Unluckily people did not attach much scientific importance to 

 the phenomena when they first appeared, and so made no notes. 



5. The intermittent nature of the phenomena, also, Hazen thinks, is 

 against the supposition that dust is the cause ; but I see no force in this. 

 It is only natural that the appearances should vary in intensity with vary- 

 ing meteorological and atmospherical conditions, and, as I have already 

 said, the dust may not have been very evenly distributed. 



6. Hazen's last objection is that ashes are opaque, and the appearances 

 indicate a transparent something. Another writer (in the " Sci. Amer.") 

 puts this objection in this way : — He says, earthly or lunar volcanic dust 

 cannot be the cause of the glows at the rising and the setting of the sun, or 

 the ordinary light from sun, moon, Mars, Jupiter, etc., would be affected. 

 But there is no diminution of this light. Therefore the cause of the glows 

 lies far beyond the sun's orbit. 



But are the premises in this argument true ? Have we not already 

 stated that a haziness of the sun has been observed at several places — e.g., 

 at Seychelles and Tokio ? And is not a change in the colour of the sun 

 and moon virtually a change in the intensity of their light ? Moreover, 

 although individually the particles may be opaque (which their intense 

 character leaves open to doubt), collectively they do not constitute an opaque 

 mass, being exceedingly minute and widely scattered. Also, before we can 

 attach much importance to this objection we must know accurately what 

 the photometer has to say on the subject. As the writers quoted do not 

 tell us this, we may presume they speak from conjecture only. 



7. Some may say that the volcanic force of Krakatoa, however great it 

 might be, would scarcely be great enough to force up such a vast amount of 

 ashes to so great a height. It is generally considered that the dust cloud, or 

 whatever it was, lay very high indeed ; but what gigantic forces were at 

 work at Krakatoa ! An electrical force was in violent action also, for 

 simultaneously with the outbreak all the telephones in Singapore were 

 unworkable, and on one line reports like pistol shots and a mighty roar 

 were continually heard ; and again the heated air, emanating from the 

 crater of Krakatoa, would carry with it to unknown heights vast volumes of 

 dust, etc. ; and incidentally I may mention that the heated air of the tropics 

 ascending as it always does, to be replaced by cooler air from the north and 

 south temperate and polar zones, would account to some extent for the dis- 

 persal of the dust. 



