288 EEPORT — 1889. 



explosion from the crater in the evening of May 4, although the gradual 

 disintegration of the cone by crumbling in during the day had made 

 such rapid progress, that the truncation of its summit was most 

 marked. This may possibly be due to partial obstruction of the lateral 

 outflow, as the reflection from the lava was much less. The next day 

 reflection was still less, and the light from the vent almost if not quite 

 invisible. Under favourable circumstances, slight reflection from the 

 lava could be seen from time to time on the cone-slopes. 



On May 17 this increased, but diminished during the following days, 

 and during the last five days of the month much black smoke or sand, 

 lapillse and breccia, were ejected. 



The last day of May I found that within -the cone a very considerable 

 crater had been formed, perhaps 40m. in diameter, and quite as deep. A 

 mixture of pasty lava cakes, pieces of old lava, and lapillo-sand was being 

 ejected, proving that the molten rock was not far from the bottom of the 

 crater. In fact, the next day the crater showed the first degree of 

 activity, which was maintained between first and second degree during 

 the whole of the month of June, with occasional slight increase in the out- 

 flow of lava. During the month of July little change occurred, except 

 from the 6th to the 8th when a markedly increased outpour of lava 

 occurred, and on the 20th and 21st, when more of the crater edge crumbled 

 in, so that for three or four days no reflection from the crater was visible. 



During August lava always continued to flow, but increased on the 

 25th with greater activity at the crater. (Fig. 5.) 



Visiting the crater early the next morning, I found that the bottom 

 of it had been raised into a rough plain ; about 8m. from the lowest edge 

 in the N.N.W. corner was the eruptive mouth with a low ring surround- 

 ing it, constituting the commencement of a cone of eruption. 



The fissure crossing the 1872 crater plain in a S W. direction is still 

 very active, giving out abundant exhalations of HCl. There are also 

 indications of weakness at the site of the May eruption of 1885. 



It will be thus seen that Vesuvius has been much more interesting 

 during the present year than last. 



Railway Tunnels in the Phlegrean Fields. — Much progress has been 

 made with the two tunnels near Baja, of the new railway line. The first, 

 or that one that enters the hill at the Baths of Nero, had been com- 

 menced before my last report, and is one that I had shown to present great 

 diflBcultips in its construction. This proved to be the case, for the tem- 

 perature very rapidly rose as the work progressed, so that 70° to 80° C. 

 was the normal temperature of the working atmosphere, which rose 

 higher when a new face of rock was detached. In a hole made in the 

 newly exposed rock, a maximum temperature of 93° C. was registered by 

 one of the engineers. The workmen, absolutely naked, worked but an 

 hour or two at a time, and came out much exhausted. I myself visited the 

 works on various occasions, ray only costume being socks and boots, and 

 I could well appreciate the great difficulties of persistently and violently 

 exercising oneself in this highly heated, and, above all, moist atmosphere. 

 Fortunately, the tunnel is slightly inclined, and when work was stopped 

 at the lower end, it was proceeded with, with much greater ease, from the 

 upper end, until at last a headway through was opened up, after which 

 the temperature rapidly fell. 



Of great interest is the fact that a number of Roman ouniculi have 



