The very remarkable and beautiful sunsets which have been so frequent of late, in which the sky has been lit up with a wondrous wealth of colouring, and with a splendour more than earthly, has given rise to much interest and speculation as to the cause of the brilliant colouring. According to one explanation, the effect is produced by the light becoming coloured in its passage through the atmosphere by an excess of water vapour, or other absorbing medium, at present in the air. The other explanation is, that the effects are the result of a superabundance of atmospheric dust, probably due to the late eruptions of Krakatoa and other volcanic mountains.