168 Jounsron-Lavis—The Eruption of Vesuvius in April, 1906. 
Casini. South, and towards Terzigno. 
(a) 0:04 m. fine, brownish-black scoria-lapilli, almost totally essential ejecta. 
(6) 0.08 m. coarse, black scoria-lapilli of essential ejecta. 
(c) 0°20 m. red and brown lapilli of different coarseness, chiefly accessory 
ejecta. 
(d) 0:03 m. of greyish dust. 
Trrzicno. (South of) in a quarry at Caposecchi. 
The three elements of the deposit are similar to those above recorded. The 
total amounts to about 0:12 m., but the accurate measurement of 
each component is obviously approximative. 
Lacgno DEL Purearorio, right or west bank just above main road, west of Somma- 
Vesuviana. 
(a and 6) 0-015 m. black sand, chiefly small fragments of essential scoria. 
(c) 0:05 m. red, minute lapilli. Accessory ejecta. 
(d') 0:012 m. red dust. Accessory ejecta. 
(d’?) 0:015 m. grey dust. Accessory ejecta. 
Laeno 8. Patrizio, just above main road to the east of Sta. Anastasia. 
(a and 4) 0:01 m. black sand. LHssential ejecta. 
(c) 0:02 m. red dust. Accessory ejecta. 
(d) 0:015 m. purple-grey dust. Accessory ejecta. 
The variations in thickness, as the distance increases or decreases from the 
eruptive centre, are very marked. Thus at Ottajano, above the town, near the 
Castello, the entire thickness attained 1:20 m. at the P. S. Francesco, in the 
middle of the town, as above detailed, 0°76 m., and at the lower extremity of the 
town only 0°55 to 0°60 m., yet this last is only one kilometre farther from the 
eruptive axis. 
At Ottajano and its neighbourhood, in the sections of the final dust-shower, 
very little difference is shown in the colour at that place, and in the sections to 
the east and south of that locality ; but immediately to the west and south-west, 
we find the dust, as at the Vallone del Purgatorio and Vallone S. Patrizio, 
markedly divided into two beds, one reddish or cocoa-coloured, emitted at an 
earlier period, and a light-grey in the final phase of the output from the crater. 
In another series of sections, taken in an oblique manner, cutting off, as it were, 
the north-west quadrant of the volcano, we shall see how these two elements 
formed the main constituents of the fragmentary ejecta on that side. I look upon 
