614 



NA TURE 



[Oct. 2. 



vatory, by several years. The Lick. Trustees will have all the 

 Observatory, excepting the large telescope and the dome to 

 contain it, finished and ready for work during 1885. As soon 

 as two perfect disks of crown and flint glass are on hand, the 

 focal length of the telescope can be calculated, and the size of 

 the great dome determined upon ; and nothing can be done 

 until this focal length is known. Nineteen trials have been 

 made by the Messrs. Feil to cast a perfect crown disk, and a 

 delay of more than two years has been incurred through the 

 difficulties and risks of the operation. It appears from the 

 letter of Capt. Goodall to Capt. Floyd, which has been referred 

 to, that Messrs. Feil have cast two disks, which they expect to 

 be suitable for the purpose. The Captain visited their works 

 early in September, and they were expected to ship one of the 

 disks to Clark and Sons early in October. There is then reason 

 to believe that the rough disks for the large telescope will soon 

 be in the hands of the optician. The successful working of 

 these disks into the proper curve for a perfect object-glass is a 

 matter of the greatest difficulty, but the extraordinary skill 

 which the Clarks have acquired leave no doubt that within two 

 or three years after the receipt of a perfect disk the whole 36- 

 inch objective (the largest possible) will be finished. While the 

 objective is making, the dome and the mounting can be con- 

 structed, so that the whole delay is and has been due to the dif- 

 ficulties incident to the opticians' work. The work on Mount 

 Hamilton has progressed as far as possible under the present 

 conditions, and it will not be long before California possesses 

 the most perfect observatory in the world, placed in the most 

 favourable situation which can be found. 



The recent works of the United States Geological Survey, 

 and especially the remarkable report of Capt. Dutton, have 

 given an opportunity to Prof. Trautschold of Moscow, to draw 

 a parallel between the geological structure of Colorado and 

 that of European Russia, which appears in the Bulletin of the 

 Moscow Society of Naturalists. In Russia, the Silurian, De- 

 vonian, Carboniferous Limestone, and Lower Permian series are 

 marine deposits, while the Upper Permian is of fresh-water or 

 terrestrial origin. The Trias and Lower Jurassic rocks are also 

 continental deposits, — or seem to be so to a great extent, — while 

 the Upper Jurassic groups are again of marine origin, as is also 

 the Chalk, which contains only islands with land-vegetation. 

 Three parts of the Tertiary series consist of terrestrial and 

 fresh-water deposits, marine deposits appearing only in the 

 south ; and the Quaternary is also a continental formation. 

 Such being, according to Prof. Trautschold, the structure of 

 Russia, he had already concluded that in the Northern 

 Hemisphere there was a general retreat of the sea during 

 Palaeozoic times, and a growth of continents, upon which the 

 Carboniferous and then the Permian floras largely increased, 

 European Russia being, during the Triassic and the first half 

 of the Jurassic periods, a continent with nearly the same out- 

 ines as now. During the second half of the Jurassic period, 

 another subsidence of the continent, and an advance by it into the 

 Northern Hemisphere, again took place, without reaching, how- 

 ever, the same level that it had had during the Palaeozoic period ; 

 the sea remaining shallow. A second retreat of the water took 

 place during the Tertiary and Quaternary periods. Similar 

 oscillations might well explain, in Prof. Trautschold's opinion, 

 the structure of the Grand Canon district, where the connec- 

 tion between the Juras-ic and Triassic is as close as in Russia. 



The next ordinary general meeting of the Institution of Mech- 

 anical Engineers will be held in the large Lecture Theatre, Univer- 

 sity College, Shakespere Street, Nottingham, on November 5. 

 The chair will be taken at 4 p.m., by the President, I. Lowthian 

 Bell, F.R.S. The following papers will be read and discussed, 

 as far as time will admit : — On the Mineral Wagons of South 



Wales, by Mr. Alfred Slater, of Gloucester ; on the Applica- 

 tion of Electro-Magnets to the working of Railway Signals and 

 Points, by Mr. Illius A. Timmis, of London ; Second Report 

 on Friction Experiments, by Mr. Beauchamp Tower, of 

 London. 



The International Congress convened to deliberate upon the 

 best means of preventing the spread of Phylloxera vaslatrix was 

 opened on Monday at Turin. Among the personages present were 

 the Duke d'Aosta, Signor Grimaldi, Minister of Commerce, the 

 Syndic of Turin, and the French, Greek, Spanish, Portuguese, 

 Servian, and Roumanian Delegates to the Congress. After a 

 short address of welcome from the Syndic of Turin, Signor 

 Grimaldi explained the object of the Congress, and dwelt par- 

 ticularly upon the necessity of common legislative measures being 

 adopted in all infected countries in such a form as not to interfere 

 with the liberty of trade. It was, however, most requisite to 

 raise barriers to the spread of the Phylloxera. 



The last issue of the Transaet'ons of the Seismological Society 

 of Japan (vol. vii. part 1) contains a paper by Prof. Milne on 

 Earth Tremors, dealing successively with artificially produced 

 tremors, natural tremors, and at some length with various instru- 

 ments constructed to record these minute movements. Micro- 

 seismology, by the way, appears to be the name of this new 

 branch of science. The results which have been obtained so far 

 do not appear to be of great importance. The motions are more 

 law-abiding than earthquakes ; but it is impossible to say yet 

 whether their systematic study will enable us to foretell an 

 earthquake, although from examples quoted it appears that 

 earthquakes are frequently preceded by great microseismic 

 activity. Nor is the cause of these constant movements under- 

 stood. Among the theories on this subject mentioned by Prof. 

 Milne is one that they may be due to slight vibratory motions 

 produced in the soil by the bending and crackling of rocks caused 

 by their rise upon the relief of atmospheric pressure. Rossi 

 thinks they may be the result of an increased escape of vapour 

 from the molten material beneath the crust of the earth conse- 

 quent upon a relief of external pressure. In the same number 

 Dr. Du Bois writes on the great earthquake of Ischia ; and a 

 catalogue of earthquakes in Tokio between July 18S3 and May 

 1S84, as observed by a Palmieri's seismograph, is also given. 

 From the annual report of the Society we observe that the com- 

 mittee appointed to report on a system of earthquake observa- 

 tions give as their conclusion that the most important observation 

 is that of time, and experiments are now being carried out to 

 obtain a suitable clock for this purpose. The next number is to 

 contain an important paper by Prof. Milne giving a detailed 

 account, with a series of maps, of 387 earthquakes recently felt 

 in Northern Japan. 



Mr. Spence Paterson, H.B.M. Consul at Reykjavik, writes 

 to the Standard that on September 9 he visited Cape Reykjanes, 

 the south-west point of Iceland, in order to observe the volcanic 

 island which recently appeared oft" that Cape. It was first seen 

 by the light-keeper at Reykjanes on July 29, and had then the 

 shape of an irregular truncated cone, with a slight hollow on the 

 top and a projecting shoulder on the north side. No earth- 

 quakes or other volcanic manifestations accompanied its appear- 

 ance, but on August 5 a series of severe shocks occurred, which 

 split the walls of the lighthouse and damaged the lamps. For 

 several days rain and fog obscured the island ; when next seen, 

 its shape had altered ; part of the south side had fallen down 

 into the sea, forming two little mounds, and leaving a steep, 

 almost perpendicular face on the south. The height of the island 

 is about two-thirds of its length. It lies about west-south-west 

 of Reykjanes. Two officers of a French war-vessel, who recently 

 visited Reykjanes, estimate its distance from the coast at nine or 



