O'Reilly — On the Constitution of Calp Shale. 569 



perience of another captain as well as his own during and subsequent 

 to the Krakatoa eruption : — 



" Ship ' Venezuela' was at Samarang on the 27th August 

 (1883) : there was intense rain in the evening ; pumice was 

 first observed in lat. 6° 43' S., and long. E. 104° 1'. The 

 vessel sailed through about 200 miles of it. The barometer 

 was very high in the morning and very low in the evening. 

 There was dust floating like a scum, about 9 inches thick, 

 on the water and pieces of pumice floating here and there 

 in it. 



" Ship ' Mei Nepoti.' — On the 26th of August was in 

 Batavia. The captain on going on board in the evening- 

 noticed the sky to be very black, as if a squall about to 

 come on ; heard explosions from 12 o'clock until 4 o'clock 

 nest morning (27th). On the 27th the dust fell from 12 

 o'clock noon until 3 o'clock p.m. After 4 o'clock a.m. heard 

 no more reports. At 8 o'clock a.m. of the 27th all the ships 

 in the roads spun once or twice round their anchors. There 

 was darkness from 8 o'clock a.m. till 1 o'clock p.m. on the 

 27th ; then noticed the tide to rise three times, at 1|- o'clock, 

 3 o'clock, and 8 o'clock p.m. of the same day, and the red 

 pumice (of which a specimen contributed by the captain) 

 was picked up on the 28th October in long. 97° 20' E., and 

 lat. 13° 20' S." 



These notes furnish evidence not merely of the vast amount of 

 pumice ejected on that occasion, but of the existence of a scum of fine 

 pumice dust (such as might be represented by the matrix of the 

 section referred to), 9 inches thick and of vast extent. Such a scum 

 would, before becoming completely waterlogged and sinking to the 

 bottom of the ocean, become inhabited by minute marine organisms, 

 such as small sponges and radiolarians, and in sinking would carry them 

 down and become deposited on the bottom of the sea as these calp 

 shales were. Taking into consideration the vast thickness of this 

 formation in Ireland and assuming that in general the calp shales are 

 largely composed of fragments of pumice as in the particular case 

 under consideration, may it not be inferred that they measure more or 

 less completely the volcanic activity of the periods to which they have 

 been referred, and in this manner add to the data furnished by the 

 trap rocks which have been fully described by the authors mentioned 

 as characteristic of the Carboniferous formation in Ireland. 



