The Tarawera Outbreak. 125 



These official reports mention the levelling of the forests 

 "by the storm, but they do not say whether any attempt to 

 use the tree-trunks as anemographs has been or will be 

 made. 



The distribution of the volcanic deposits is well shown on 

 Dr. Hector's map. The mud lies in a straight, broad track, the 

 axis of which bears about one point west of north. This 

 should indicate the prevalence of a steady wind from the 

 south or near by. 



Yet the people at Rotorua state that the wind there was 

 first from the south-east, and that it then blew with great 

 violence from the south-west. If the south-westerly direc- 

 tion of the wind had prevailed generally, it would have 

 carried the falling mud away to the north-east of the 

 volcano, which it certainly did not do according to 

 Dr. Hector's plan. 



It appears to me that the mud distribution is more con- 

 sistent with the theory of a local indraught, and tliat the 

 wind direction at Rotorua was a purely local phenomenon. 



The sand, again, is distributed over a differently-shaped 

 and a differently-placed area. Instead of having a long 

 band we have an oval. It has fallen far to the eastward of 

 the mud track, and also some miles to the south of the 

 vents. From the latter circumstance it is clear that over 

 this part of the area, during some part of the time, or at 

 some altitude, a wind must have blown from the quarter 

 exactly opposite to that of the wind which spread the 

 mud. 



The grey ash is distributed over an oval also, but the oval 

 is a much larger one. 



The discrepancies between the tracks of the several di^st- 

 clouds and between these and the recorded winds may be 

 susceptible of the following explanation: — It may be that 

 at the earth's surface a broad zone of southerly wind pre- 

 vailed, within which a small cyclone raged round the 

 volcanoes, like an eddy in a wide river. The main stream 

 may have carried along the heavy mud, and so have pre- 

 served to it the straightness of direction which is so marked 

 a feature of its distribution. The dust, which was carried 

 at once into the higher regions, escaped the wetting which 

 made mud of that which remained within the plane of the 

 southerly wind, and being light, because dry, it was easily 

 whirled about to different points by the different winds, or 

 by the gyratory movement which was prevailing above. 



