498 



NA rURE 



\_March 24, 1881 



It is worth obsemng that from this side of the island the four 

 or five historic eruptions have occiu-red, and all the principal 

 thermo-mineral springs are confined mostly to this district. 



It is at this very spot that the late earthquake has taken place, 

 resulting in the total destruction of Ca-amicciola, with the ex- 

 ception of the hotels, baths, and a few well-constructed privafe 

 houses. A hundred and twenty bodies have been excavated, 

 and they are not all, besides 1 60 seriously wounded. At the 

 village of Lacco thirteen houses have fallen, and five deaths are 

 reported. 



On March 4, at five and a half minutes past one p.m., a terrific 

 shock shook the whole island, but its maximum intensity was at 

 this point leaving Ischia and Forio almost uninjured, togfther 

 with the villages on the opposite side of the mountain. 



There was but a moment of premonitory trembling, w hen the 

 terrific blow shook the houses about the ears of their inhabitants. 

 The corpse of the shoemaker was found in his usual position, 

 with the last between his knees, and we saw the corpse of a 

 woman with the half-finished stocking in her hand and the 

 needle in its sheath. The two cases show the suddenness of the 

 catastrophe. 



The first shock was described as a sudden blow beneath the 

 feet, followed by a series of undulations, which appear from 

 accounts to have radiated from a point which I shall immediately 

 describe. This was followed shortly by faint vibrations, accom- 

 panied by loud subterranean thunder, such as was heard in the 

 slight earthquake of last July. 



On vi^iting the island a few hours after we were struck by the 

 severity of the shock and by its extremely limited area. Fol- 

 lowing the methods adopted by our eminent countryman Mr. 

 Mallet, F. R.S., in his investigations of the great Neapolitan 

 earthquake of 1857, we have come to the conclusion that the 

 undulations occurred in a series of closed curves radiating from 

 a point which must have been situated about a quarter of a kilo- 

 metre to the south-west of the upper town, that is in the direction 

 of Lacco. 



It is interesting to note that the seismographs at Naples and 

 Vesuvius were not at all affected by the earthquake. This led 

 Prof. Palmieri to conclude from the extremely local effects pro- 

 duced that the phenomenon was due to the excavation and 

 removal of matter by the mineral springs and the collapse and 

 falling in of the superincumbent ground. It feems difficult to 

 satisfy oneself with the theory of my respected teacher and friend 

 Prof. Palmieri for the following reasons : — 



1. The collapse of earth in Cheshire in no way produces efi'ects 

 at all similar or equivalent to those under consideration, and yet 

 the amount of salt in solution removed is equal to much more 

 solid matter than is removed by the dilute mineral waters of 

 Ischia which are also small in quantity. Landslips like that of 

 Lyme Regis are quite incomparable in effects to the present 

 case. 



2. The waters that issued immediately after the disaster were 

 as usual clear, and flowed at the same rate. If this explanation 

 was tenable, then the collapse of the earth should have forced 



■ lut a large body of water and vapour and have rendered the 



■ ormer turbid and muddy. Such however was not the case. 



3. The disturbance in Ischia was coincident vrith the seismic 

 movements that were felt in various parts of Europe from the 

 2iid to the 5th of March, and which was severe throughout 

 Northern Italy. 



We know from the following facts that Ischia cannot be 

 eckoned amongst extinct volcanoes. The great number of 

 fumaroles and thermo-springs that exist on its surface ; the sand 

 111 the sea-shore in some parts is so hot a few inches from the 

 urface that the hand cannot be borne in it ; the continual 

 eismic disturbances to which it was and is subject — all point to 

 the conclusion that there still exists igneous matter not far from 

 the surface. 



The seismic waves of the beginning of March causing in- 

 creased tension in the igneous matter through which they 

 travelled would tend to rupture the superficial crust at its 

 weakest point ; the Island of Ischia presents to us such suitable 

 conditions, and the volcanic matter, vapour, or lava may by 

 those means have endeavoured to force its way towards the 

 surface. 



The formation of a fissure, together with the blow that would 

 he produced by the immediate falling of such, would explain the 

 phenomena. Much the same results occur from the formation of a 

 dyke in an active volcanic mountain ; in fact the conditions may 

 be looked upon as analogous. 



Although lava has failed to reach the surface on the present 

 occasion, a repetition may be sufficient to produce an eruption 

 such as has often occurred at this spot. VVe may look for the 

 homologues of the present earthquake in that of A. D. 63, pre- 

 ceding the outburst of Vesuvius in 79, or those that disturbed 

 Pozzuoli and its neighbourhood immediately before the forma- 

 tion of Monte Nuovo, but which were not felt at Naples. 



The fact that the undulations produced little effect on the 

 southern side of the island shows the extreme thinness of the 

 earth-crust at this spot ; the weight and bulk of the superficial 

 configuration acting as deterrent agents to the propagation of 

 the seismic undulations to any great distance. The earthquakes 

 in Ischia have at times been very disastrous, compelling various 

 Greek colonies to forsake the island. There is generally a 

 slight shock about once a year, nearly aU\ays accompanied by 

 subterranean thunder. These have sometimes caused injuries, 

 as on February 2, 182S, when three or four houses fell and 

 some thirty people were killed. The details of the observa- 

 tions being made will be published as soon as they can be 

 fonnulated . 



It is an interesting fact that since writing the above, on 

 comparing notes with Signor P. Franco, my colleague, although 

 our observations were quite independent and unknown to each 

 other, yet we have arrived at exactly the same conclusion in 

 almost every detail. 



H. J. Johnston-Lavis 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE 



Oxford. — The following notice respecting scholarships in 

 Natural Science has been published by Merton College : — 



There v ill be an election in June next to one (or two) Physical 

 Science Postmasterships. 



The examination will begin on Tuesday, June 28; it \\ill be 

 held in common with Magdalen College, and at the same time 

 and place. Candidates may give in their names at either College, 

 but all will be regarded as standing at both, unless special notice 

 is given to the contrary. In the event of election a candidate 

 will be requested to state which College he would prefer. The 

 Postmasterships are of the annual value of So/., and are tenable 

 for five years from election, provided that the holder does not 

 accept or retain any appointment incompatible with the pursu- 

 ance of the full course of University studies. After two years' 

 residence the College may raise, by a sum not exceeding 20/. per 

 annum, the Postmastership of such Postmasters as shall be 

 recommended by the Tutors for their character, industry, and 

 ability. Candidates for the Postmasterships, if members of 

 the University, must not have exceeded six terms of University 

 standing, b\it there is no limit of age. The subjects of examina- 

 tion will be Chemistry and Physics. There will be a practical 

 examination in Chemistry. Candidates will have an opportunity 

 of giving evidence of a knowledge of Biology ; but it must be 

 borne in mind that in such cases the examiners w ill look for 

 evidence of an acquaintance with the principles of Chemistry 

 and Physics at least equal in extent to that which is required in 

 the Preliminary Honour Examination in the Physical Science 

 School. A paper will be set in Algebra and Elementary 

 Geometiy (Books I. -VI.), and a Classical paper of thcjstandard 

 required by the University for Responsions. 



Magdalen College has published the following notice respect- 

 ing Natural Science Scholarships (Demyships) : — There will be 

 an election at this College in June next to not less than seven 

 Demyships, of which one at least will be Mathematical, one at 

 least in Natural Science, and the rest Classical. No person will 

 be eligible for the Demyships who will have attained the age of 

 twenty years on October 10 next. The stipend of the Demy- 

 ships is 95/. per annum, inclusive of all allowances : and they 

 are tenable for five years, provided that the holder does not 

 accept or retain any appointment which in the judgment of the 

 electors will interfere with the completion of his University 

 studies. 



The Oldham Lyceum and Science and Art Schools, opened by 

 Lord Derby last Thursday, seems to be a handsome and useful 

 building, and imder Mr. Phythian's superintendence we have no 

 doubt much good work will be done in the future as in the past. 

 Chemical and physical laboratories and other arrangements of 

 scientific work have been provided for. 



