ABSTRACT OF PROCEEDINGS. XIX. 



and described interesting observations of Dr. T, A. Jaggar, 

 Junr. and others at the volcano at Kilauea. 



exhibits : 



1. Mr. A. B. Hector briefly referred to certain analogies 



between sound and light in connection with the move- 

 ments of approaching and receding bodies. 



2. J. L. Somerville, B.Sc, and W. G. Woolnough, d.Sc, 



furnished the following note on a brilliant display of 

 marine phosphorescence which was seen at Pittwater, 

 Broken Bay. 



" On the evening of 6th September, 1920, we spent some 

 time in watching, from Newport Jetty, a somewhat excep- 

 tionally brilliant display of marine phosphorescence at Pitt- 

 water. The time was 8 "45 p.m. and the night was intensely 

 dark, phenomenally still and oppressively silent. The whole 

 surface of the bay was sparkling with pin-points of phosphor- 

 escent light, reminding one of a spinthariscope. 



When a stone or clod of earth was thrown into the water 

 there was the usual splash of pale phosphorescence, the comet- 

 like effect of the brilliantly illuminated sinking object, 

 followed by a 'tail' of ghostly light, and the phosphorescent 

 air bubbles rising through the water as they became detached 

 from the missile. If several stones were thrown into the 

 water in succession the response became progressively 

 weakened; in other words the phosphorescence exhibited a 

 decided fatigue effect. 



The fact which was unique in our experience of such 

 phenomena was that it was accompanied by an infinitesimal, 

 though distinctly audible crackling sound, somewhat resembl- 

 ing that of an electrical discharge, or the boiling of a very 

 viscous liquid. Our attention being drawn to the fact we 

 examined the matter critically, and were able definitely to 

 connect the appearance of each flash in the confined space 

 under the jetty with an individual minute explosion. 



