BY R. VON LENDENFELD, PH.D. 441 



of dust was the cause of the eruption. I have given the reasons 

 above why I believe the former not to have been the case, and we 

 must now therefore consider the second alternative. 



A dust cloud Hearing the earth must necessarily influence the 

 earth by its attraction. The general gravitation will attract the 

 dust cloud to the eai-th, but also the latter towards the former. 

 When the dust cloud comes near the earth this attraction will be 

 local, near the place where it reaches the outer surface of the 

 atmosphere very much stronger in the moment when it falls than 

 anywhere else, the part of the globe nearest the falling dust cloud 

 will be attracted in a great measure. If the globe were liquid 

 the consequence of this local attraction would be, that on and 

 near the surface from those parts around the place where the dust 

 cloud was descending the mass would tend to flow towards that 

 cloud. The firm crust of the earth cannot of course yield to such 

 a local attraction from without, which can only disturb the 

 equilibrium on the surface ; but the outer liquid coating, the sea, 

 and the inner liquid or semi-liquid mass can obey, and in this case 

 did obey the strain. The sea rose high and swept over the 

 islands, and the liquid mass in the interior of the earth broke 

 forth at a place of little resistance, where the pre-existing 

 volcanoes prove the earth's crust to be weaker than elsewhere in 

 the vicinity of that place, where the cosmic dust cloud struck the 

 atmosphere. 



I have ascertained an interesting fact, which goes far to prove 

 the correctness of these statements, and in fact the conclusions 

 drawn therefrom brought me to the explanation which I have 

 presented above. 



Tidal waves caused by volcanic eruptions are not rare. They 

 are always caused by a centrifugal shock, and consequently consist 

 of high waves much higher than those caused by the highest tide, 

 which are separated f iom each other by steep rare valleys. In this 

 case, I had occasion to observe the tidal waves at Lyttleton. Here 

 the irregularity consisted in a sinking of the water, which during 

 the whole day never reached even middle water-mark, and was at 



