April 14, 1 881] 



NA TURE 



569 



The third paper on steel was by Mr. J. R. Ravenhill, and 

 gave an account of the improvements which have recently been 

 made in mild steel castings. Many portions of machinery and 

 steam-engines which till quite recently were invarialily made of 

 ca-t iron can now be formed of cast steel, with the attendant 

 advantages of gain in strength and saving in weight. 



Perhaps the most interesting paper of the four was that by 

 M. BeiTier Fontaine, the eminent French naval architect, "On 

 the Use of Mild Steel for the Constraction of the Hulls of 

 Ships in the French Na\7." The French were undoubtedly 

 the first to introduce this material into the national navy ; 

 but though their experience of it is longer than our own, 

 tliey do not seem to have acquired the same confidence in its use 

 which is now felt in this country. For instance, we are in the 

 habit of constructing the entire hulls of ships, including the 

 below-water plating, of steel ; the French, on the other hand, 

 continue to U5e iron for all work which has to be exposed to the 

 action of sea water. The reason advanced is that they find that 

 steel \\hen immersed in salt water corrodes with far greater 

 rapidity than iron. M. Berrier Fontaine quotes as examples 

 two oTinboats, the Epcc and the Tromblon, the hulls of which, 

 completely steel-plated, have both given proof of rapid and 

 deep corrosion. "The Tromblon was launched at Toulon on 

 January 20, 1875, and remamed afloat till October 27 of the 

 same year. During that period of nine (months it was found 

 necessaiy to dock lier three times, that it is to say, about every 

 two months to _paint the hull, the plates being rapidly and 

 deeply attacked, especially in the neighbourhood of the water- 

 line. The progress of this corrosion went on with such unusual 

 rapidity, that \ihen the time came to pass the Tromblon into the 

 reserve it was thought necessary to haul her on to a slip instead 

 of keeping her afloat." The whole subject of the corrosion of 

 steel plates is at present involved in great mystery, and no two 

 authorities seem able to agree about the cause. In the Enghsh 

 Admiralty it is commonly believed that it is due to the presence 

 on the surface of the plates of portions of black oxide, which 

 constitute with the steel so many active galvanic couples, which 

 of cour-e rapidly promote corrosion, and hence great care is 

 now taken to remove all traces of this oxide before the plates 

 are coated. Whatever may be the cause, it is perfectly certain 

 that the experience of English builders does not tally with 

 that of M. Berrier Fontaine in this particular. Certain cases 

 of corrosion have no doubt occurred in this country, and the 

 hull of the Ins is an example in point ; but as far as present 

 experience goes such cases are the exception instead of the rule. 

 M. Berrier Fontaine gives an interesting account of the tools 

 and other plant used in the French dockyards for the working of 

 steel. He describes also the early difficulties which the work- 

 men experienced, all of which have been successfully overcome. 

 As regards the process of manufacture adopted in France, it 

 appears that equally good resuUs are obtained trom the Bessemer 

 and the Siemens meihods, so much so that when contracts are 

 given out it is never specified that the material is to be prepared 

 by either of the two processes. In some works the Siemens 

 system is employed for the superior sorts of steel, and the 

 Bessemer process reserved for inferior descri|Jtions, such as rails, 

 while in other works exactly the oppo^ite takes place. In this 

 country, on the contrary, it is almost universally the rule to 

 specify the Siemens process for the production of mild steel 

 plates for ship-building and for boiler purposes. 



DUNES AND MOVING SANDS 



IN a communication made to the Russian Society of Natu- 

 ralists, M. Sokolofif has given a description of the dunes 

 which are seen close by Sestroryetsk, at the eastern end of the 

 Gulf of Finland. The whole of the Lsthmus between the Gulf 

 and the basin of Sestroryetsk is covered with dunes which have 

 a double origin. Those which are close by the sea-shore are 

 old shore-ridges, mostly covered with vegetation, parallel to one 

 another, and having each the form of a straight line, while those 

 which are situated more east are true dunes, built up of sand 

 driven by the wind. They have the direction north and south, 

 and they reach the height of a hundred feet. Several of them 

 are quite covered with pine-forests and with moss, while others 

 are almost quite naked. The latter are constantly brought into 

 motion by the west wind, and south of the Sesti-a River a high 

 dune will shortly cover the houses of the working men of the 

 Sestroryetsk manufactory. This dune, about 700 feet broad, 

 has already covered several houses, and it is always advancing 



further, forming smaller parallel dunes fifteen feet high ; its 

 western side is covered with numerous excavations, from which 

 the wind has taken the sand to move it further east. M. Soko- 

 Joffi \\hile agreeing with the well-kn .wn classification of dunes 

 established by the explorer of Sahara, M. Vatonne, thinks that 

 the dunes of the deserts, which owe their origin to the action of 

 wind, might be very easily distingui'-hed from the mostly lower 

 ridges which appear on the sea-shores under the influence of 

 waves, these last usually having the form of straight lines, whilst 

 the true dunes always have a semicircular form. M. Severtzoff 

 observed after this communication that in the steppe of Kyzyl- 

 koum, true dunes often have the same form of parallel, quite 

 straight ridges. However, having at their origin a circular form 

 which is so characteristic of the barkhans of the stepjie, they 

 lose by and by this form, and several smaller dunes, uniting 

 together at their ends, take the form of a long straight ridge 

 perpendicular to the prevailing direction of wind. M. Moush- 

 ketoft", who has made a close acquaintance with the sands of 

 Central Asia, observed that the.^e sands, which are all sporadic, 

 being spread among older formations, are very different as to 

 their extent, their stratigraphical and petrographical characters, 

 and their origin. They might be subdivided into three different 

 classes : — I. Those which have a marine origin and which might 

 be observed on the south-eastern shores of Lake Aral, and 

 especially in the Kara-koum steppe. They are about 250 yards 

 and 70 feet high, and mostly parallel to the shore. They 

 are typical marine dunes, but their extension closely depends 

 upon the extension of the Arab-Caspian formation, the fossils of 

 which are always found broken in these sands. 2. The fluvial 

 dunes, which are very common in the valleys of the Amou, Syr, 

 Sourkhan, and others ; their height rarely exceeds 10 to fifteen 

 feet, and their length is from 100 to 150 feet ; their s.md is steel- 

 gray, and contains gypsum and clay. 3. The bnrhham are sub- 

 aerial formations ; they prevail in the central part of the steppe 

 Kyzyl-koum, but are rather rare in the Kara-koum steppe. They 

 have the form of a sickle, and are somewhat conical, their maxi- 

 mum hei'^ht being as much as 20 to 30 feet ; their slopes are 

 very different, that which is under the influence of the wind 

 having an inclination from 5 to 13 degrees, whilst the other 

 slope is short and steep, the inclination reaching sometimes as 

 much as 43 degrees ; they consist of a dirty-yellow or red sand, 

 owing to their origin in the Tertiary sandstone, :or sometimes in 

 other harder rocks, as for instance, in the valley of the Hi River. 

 Sometimes typical barkhans are met with among dunes, being a 

 secondary formation arising out of the marine dunes. As to the 

 plantations of trees on dunes, M. Moushketoff thinks that it would" 

 be far more rational first to determine whence the sand is brought 

 by the wind, and to make the plantations of trees or bushes, 

 according to the chemical character of the sand on this place, 

 instead of making them on the dunes themselves. 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE 



Manchester. — We learn that the Council of the Owens 

 College proposes shortly to establish an independent Chair of 

 Applied Mathematics. 



Edinburgh. — The tercentenary of the University of Edin- 

 burgh will be celebrated in 1883. The senatus are to invite 

 representatives from other universities to be present ; they also 

 propose to bring out a history of the University during the first 

 300 years. 



The winter session of the College of Agriculture, Downton, 

 Salisbury, was brought to a close on Wednesday, when the prizes 

 were presented by Earl Nelson, who dwelt at consider-able length 

 on the present state and future prospects of British agriculture, 

 taking a very hopeful view of the latter. The High Sheriff of 

 Wilts warmly advocated such a combination of science with 

 prnctice as was in vogue at the College. The Scholarship 

 offered for competition amongst students who have conii'leted 

 their first year at the College was aw arded to Mr. Louis John- 

 stone, son of Sir Harcourt Johnstone, Bart., Hockurss Hall, 

 Scarborough, the Hon. Victor A. N. ViooA proxime accessit. 



SOCIETIES AND ACADEMIES 

 London 

 Royal Society, March 31. — "Permanent Molecular Torsion 

 of Conducting Wires produced by the Passage of an Electric 

 Current," by Prof. D. E. Hughes, F.R.S. 



