A GREEN SUN AND ASSOCIATED PHENOMENA. 403 



itself the rainfall was 19*17 inches, and in Masulipatam 1571 inches above 

 the average. We see then that aqueous vapour was present in large quantities, 

 and that the presence of aqueous vapour is sufficient to account for the 

 phenomena, so that it seems unscientific to call in the aid of any other agents, 

 such as dust or sulphurous vapours, unless their actual presence can be proved, 

 which, I submit, has not yet been done. Assuming then that the cause was 

 aqueous vapour, the farther question arises, Why the phenomena should not be 

 more frequently observed 1 ? This question cannot perhaps be fully answered at 

 present, but some light can, I think, be thrown upon it by the following con- 

 siderations: — In most cases, where we have an excessive amount of vapour 

 present in the atmosphere, part at least is condensed into clouds, and these 

 even when light, form a screen near the horizon which shuts out the sun at the 

 time when the greenness would be observed. In the present case, on the other 

 hand, the vapour was almost entirely uncondensed, only a very light haze being 

 observed, and a few clouds low down on the horizon. The vapour was also at 

 a greater height than usual, and was probably diffused through a great depth of 

 the air; while in India, at least, the meteorological conditions near the surface 

 of the ground prevented the formation of low clouds. 



An interesting question arises as to whether electrical action may not have 

 had something to do with this distribution of moisture. The observations 

 already described, both those made with the electrometer and those made on 

 lightning, show that the air was very highly charged with electricity. I am 

 not prepared to lay much stress on the electrometer observations, however, 

 until I have had an opportunity of investigating more fully the ordinary state 

 of the atmosphere during the prevalence of west and south-west winds. The 

 circumstance that the potential of the air was negative only when the wind was 

 westerly, and even then only when the surface of the ground was hot, seems 

 to indicate that the chief cause of the peculiar electrical state lay in the lower 

 parts of the atmosphere. At the same time, it seems well to record these 

 electrical observations along Avith the other meteorological ones. Even 

 neglecting the electrometer observations, we have still various indications of 

 an abnormal electrical state, for all the clouds that were formed about this time 

 were evidently highly electrified, and the abundant displays of sheet lightning — 

 which I ventured to say were not due to the reflection from distant storms— 

 accompanied by occasional flashes of forked lightning, were indications of the 

 great storm which burst on October 2nd, when the vapour had at length con- 

 densed into clouds. In this connection, it ought to be noticed that the storm 

 of October 2nd was one in which the discharges took place almost entirely 

 between cloud and cloud. I do not know that there is sufficient experimental 

 data to show whether or not highly electrified vapour would be less ready to 

 condense into clouds than non-electrified vapour, but it seems probable that 



