HARDWICKE'S SCIENCE-GOSSIP. 



261 



GEOLOGY, &c. 



The Earthquake at Ischia. — Mr. H. Johnston- 

 Lavis, whose name is familiar to many of our readers 

 from the excellent papers he contributed to our 

 pages a short time ago on volcanoes, has been person- 

 ally studying the effects of the earthquake at Ischia, 

 and he sent a paper on the subject to Section C at 

 the British Association. He gave the results of his 

 observations as follows : — The iso-seismals have 

 almost exactly the same form and arrangements as in 

 1 88 1, but from the far greater violence of the shock 

 they are naturally larger. The houses were ruined 

 to such an extent that hardly the stumps of the walls 

 were left, and it was rare to find a piece of masonry 

 not in fragments, or two or three stones still attached 

 to each other. Objects were projected considerable 

 distances ; the iron tie-bars, put into walls after the 

 1S81 injuries, were broken and bent like thin iron 

 wire. The effect of geological structure was remark- 

 able. Most of the houses on the brink of a valley, 

 where the tufa was loose and incoherent, were quite 

 destroyed from the fissures of an incipient landslip. 

 Building with foundations on the loose alluvial tufas 

 of the plains of valley-bottoms suffered less than 

 others built directly upon the solid tufa. A number 

 of landslips occurred — three remarkable for their 

 extension. The reported fissures from which vapour 

 was said to have escaped were really the sudden 

 exposure of hot and moist tufa. He could find no 

 change, either in the level of any locality, or in the 

 fumaroles or mineral waters. The wells, said to have 

 been dried up, were in two cases merely cisterns for 

 rain-water. Cliff edges either slipped away or were 

 fissured ; roads along declivities either slipped down 

 bodily, or were divided by fissures. There were 

 many facts that negatived the idea of a submarine 

 eruption. Fontana, as in 1SS1, again showed a set 

 of injuries dependent on a vertical shock, but the 

 damage was much more strongly marked. There 

 were a set of fractures denoting a wave path coming 

 from the north at a very low angle of emergence. 

 The explanation of 1881 seemed to be confirmed. 

 The vertical injury seemed to be due, as then, to the 

 conduction along a column of trachyte, followed by 

 the direct shock from Casamicciola, which produced 

 the second set of fissures. The coast of the island 

 showed no apparent change of level. The azimuths 

 were regular, except near the mass of trachyte, which 

 seemed to have reflected the shock so that the build- 

 ings received a direct and a reflected wave path, 

 producing two sets of fissures, which caused compli- 

 cation. The focus seemed to have been an enlarge- 

 ment of the former one, and occupied almost the 

 same topographical position, except that its northern 

 extremity was more prolonged. The molecular 

 velocity had not been ascertained. 



The Lower and Midland Bagshot Sands. — 

 The Rev. A. Irving, F.G.S., contends in the "Geo- 

 logical Magazine " that the well-known green colour 

 of these beds is not due to mineral matter, but to 

 vegetable impurities. 



Erratic Blocks.— The British Association 

 Committee appointed to report on these objects, 

 stated that a remarkable group occurs at Crosspool, 

 near Sheffield, at a height of 730 feet above the sea. 

 It consists of slate rock, a tuff from the Borrowdale 

 volcanic series of the lake district, carboniferous 

 limestone and chert from North Lancashire ; speci- 

 mens also occur which were probably derived from 

 the East Lowlands of Scotland, with magnesian 

 limestone from the north-east of England. Near 

 Clun, Shropshire, boulders from Rhayader and 

 Machynlleth and neighbourhood are recorded. The 

 highest boulder is upon Black Hill. It travelled from 

 Rhayader, twenty-three miles west-south-west, and has 

 an elevation of about 1400 feet. The report included 

 a description of an enormous number of boulders, 

 spread over an area of about two miles long by half a 

 mile wide, the longer direction being south-east of 

 Markfield, Leicestershire, from whence they were 

 derived. It also gives an account of the erratics of 

 the north of Herefordshire. At Kelsall, on the ridge 

 dividing the district draining into the Thames from 

 that draining north and north-east into the Cam, are 

 two boulders lying about 500 feet above the sea level. 

 The boulders noted point generally to a derivation 

 from the Midland oolites and coal measures, and 

 from crystalline rocks farther north. 



The Common Inorganic Substances. — Mr. 

 Thomas Laurie is publishing a new work on quali- 

 tative chemical analysis of the common inorganic 

 substances, by Mr. A. H. Scott White, B.Sc, B. A. It 

 is prepared specially with a view to the preparing 

 of candidates for the examinations of the London 

 University and South Kensington and the Local 

 Examinations of Oxford and Cambridge. 



The Origin of the Rhinoceroses. — At the 

 British Association meeting, Messrs. W. B. Scott, 

 and H. F. Osborne, two American naturalists, read 

 a paper on this subject, based upon extensive 

 researches made by them in the Tertiary lacustrine 

 deposits in the North-Western Territories. There, 

 they believe, they have discovered the ancestor of 

 the rhinoceros group — an ancestor from which also 

 the tapirs have descended — in a fossil animal called 

 Orthocynodon. 



Nordenskiold's Voyage to Greenland. — 

 News has reached us from Baron Nordenskiold of his 

 endeavour to penetrate into the interior of Greenland. 

 His party made their way nearly 300 miles inland, 

 when they reached the height of 7000 feet. Baron 

 Nordenskiold was originally of opinion that the 



