382 Transactions. — Geology. 



line from Gisborne to Tarawera is just 90 miles ; the height, 

 therefore, of the cloud of vapour and dust which was visible 

 here at the time of the eruption must have been veij great. 

 An object at that distance, to be visible at all on the horizon, 

 must be at least one mile in height above the level of the sea. 

 It is not possible to obtain an absolutely correct measurement 

 of tlje height of the cloud above the horizon, but a close approxi- 

 mation can be arrived at by the aid of other objects with which 

 it could be compared. In this way it appears that the angular 

 measurement of the height of the cloud, as seen from Gisborne, 

 was from 3i to 4 degrees, corresponding to a height aljove the 

 plane of the horizon of from 5-5 to 6-3 miles. For the full 

 height, we must add to this the distance between the plane of 

 the horizon and the top of the mountain, which will bring the 

 whole height, at the lowest computation, to a little over 6 miles 

 from the top of the mountain. 



Art. XL VIII. — Notes on the Eruption of Tarawera, as ohsei'ved at 



Opotiki. 



By E. P. DuaiERQUE. 



[Read before the Auckland Institute, 21st July, 1886.1 



On 10th June, 1886, at about 2 a.m., people were aroused by 

 violent noises as of peals of thunder, and volcanic rumblings, and 

 towards the south-west the sky was illumined with strong light, 

 from the midst of which at intervals shot forth balls and forks 

 of fire. 



From about 2 till 9 a.m. there was a succession of shocks 

 of earthquake of moderate force, accompanied by a peculiar 

 floating or rolhng, as it were, of the earth. 



At about 3 a.m., the sky at the time being perfectly clear 

 and starlight, an inky-black cloud rose in the south-west and 

 drifted towards the north-east, and gradually quite overspread 

 the heavens ; and a rain of fine ash, and subsequently dust, 

 commenced, which lasted till noon, and covered the Opotiki 

 district to a depth of about 1^ inches. The air was unusually 

 cold. It was pitch dark till 10.20 a.m., at which hour 

 the fall became slighter and daylight gradually appeared, and 

 the rest of the day was twilight. 



Animals were greatly distressed, and cattle gave vent to 

 constant bellowings. Many small birds died, and insect hfe 

 suflfered severely. 



No tidal disturbance was noted. 



