56o 



NATURE 



{Oct. 3, 1889 



bins of large size, where it soon becomes very hot, reaching a 

 temperature of 60° C. (140° F.). This temperature was sufficiently 

 high to kill or at least prevent the growth of nearly all animal 

 •and vegetable species, 50° C. being the upper limit. Upon the 

 proper examination of this hot material one soon finds that a 

 single species of Bacteria [Racillus btityricuni) is associated with 

 •the fermentation and subsequent rise in temperature. Further 

 tests prove that it is tlie cause of these changes. Secondary 

 changes are very liable to occur as the heat decreases, and lactic 

 •and acetic acid, the latter often in large amounts, are produced. 

 Possibly alcohol is sometimes, but never as a first product of the 

 hot material. 



On the whole, this the thirty-eighth annual meeting of the 

 American Association for the Advancement of Science may be 

 considered to have been a successful one. Close upon two 

 bundred papers were actually read in the various Sections, some 

 of these of course not reflecting that "dry light " which is supposed 

 to heat upon all scientific investigation, yet the majority of them 

 ■evincing real and enthusiastic work on proper lines. One thing, 

 however, might have been noticeable to an English ear, many of 

 the writers seemed to possess a greater mastery over abstruseness 

 of subject than over elegance of diction. 



Many eminent men, some famous in both hemispheres, were 

 present. The total number of persons in attendance on the 

 meetings, and actually belonging to the Association, either as 

 Fellows, Members, or Associates, was between four and five 

 hundred. 



Financially, the Association is declared to be in a better posi- 

 tion to-day than ever it has been before. The annual income is 

 at present about .$6000. It has also the sum of $4500 invested 

 at 5 per cent., the interest of which is devoted to the furtherance 

 of original research. For the ensuing year this sum has been 

 apportioned thus: $150 to. Prof. Moseley to continue his re- 

 searches on the velocity of light in the magnetic field ; and $50 

 to Prof. Attwater for the purpose of investigating the heats of 

 combustion of certain mineral and vegetable compounds. 



Indianapolis and the third Wednesday in August were chosen 

 as the place and time of meeting for 1890. Mr. G. L. Goodale, 

 of Cambridge, Massachusetts, was elected President for the 

 •coming year. 



The meeting was closed by a public gathering, at which many 

 complimentary speeches were made both by hosts and guests. 



Arnold Haultain. 



THE IRON AND STEEL INSTITUTE. 



T 



HE autumn meeting of the Iron and Steel Institute was held 

 last week in Paris under the presidency of Sir James 

 Kitson. The meeting was held in the rooms of the Societe 

 d'Encouragement, and was addressed, in the first instance, by 

 M. Eiffel, President of the Societe des Ingenieurs Civils, and by 

 M. H. de la Goupilliere, President of the Societe d'Encourage- 

 ment. The President of the Institute, after thanking M. Eiffel 

 •and M. de la Goupilliere for their kind hospitality, announced 

 that the Council had awarded the Bessemer Medal to M. Henri 

 Schneider, of Creusot, for his services to the iron and steel trade 

 of France, to whom it was presented on Friday by Sir Lowthian 

 Bell. Sir James Kitson made a brief address, referring to their 

 last visit to Paris in 1878, under the distinguished presidency of 

 the late Sir William Siemens, to the increase in the roll register 

 •of the Institute which had taken place since that date. He drew 

 attention to the improvements which had taken place during the 

 last decade in the metallurgy of steel and iron ; the commercial 

 development of the Siemens-Martin and Thomas-Gilchrist steel 

 processes ; the increased development in the manufacture of steel 

 owing to the extension which had taken place in its applications. 

 The Eiffel Tower was an elegant example of the scientific power 

 and imaginative genius of French engineering, whilst the French 

 •chemical study of the processes of metallurgy had rendered great 

 service, not only to their own industry, but to that of the world 

 at large. The names of many eminent French metallurgists 

 were mentioned, and the work they had done was briefly 

 referred to. 



The business of the meeting was then proceeded, with, viz. the 

 reading and discussion of the various papers which are referred 

 to below. 



Prof. S.Jordan's paper, "Notes on Iron and Steel Manufacture 

 in France in 1887, and as illustrated by the French exhibits at 

 Paris," the first paper read, was of a statistical c'laracter, and 



compared the present production of these metals with what it 

 was ten years ago. 



The Channel Bridge. — This was a paper by Messrs. Schneider 

 and Co., of Creusot, and M. H. Hersent, Past-President of the 

 Societe des Ingenieurs Civils, descriptive of a bridge for con- 

 necting England with the Continent. The paper consists of 

 three parts, an introductory notice, a general description of the 

 bridge, and of the superstructure, being preliminary projects of 

 M. Hersent and Messrs. Schneider respectively. From the 

 introductory notice it would appear that projects have been 

 submitted by Messrs. Fowler and Baker, but these are not 

 published in the paper. 



It is proposed that the bridge should span the Channel at 

 about its narrowest portion — namely, between Folkestone and 

 Cape Griznez, a distance of 25 miles, by which means also the 

 sand-banks of Varne and Colbart can be taken advantage of, 

 thereby diminishing the height of the piers necessary to be 

 erected. These banks are in mid-Channel, about 35 miles apart, 

 and are separated by a depression of between 80 and 90 feet 

 deep ; this is also about the depth between the bank and the British 

 coast, whilst on the French side, between the Colbart Bank and 

 the Cranaux-QLufs, the bottom sinks somewhat abruptly down to 

 132 feet, attaining 180 feet about midway across, when it gradually 

 rises again. In these parts the chief difficulties would be 

 encountered in laying the foundations. As the result of frequent 

 experiments, it is found that the blue and white chalk which 

 forms the Channel bottom is capable of supportinga load of from 

 140 to 170 pounds to the square inch, and the surface of the 

 bases of the piers has been so calculated that the foundations 

 should not have a greater load on them than the smaller of these 

 amounts. This would imply that no factor of safety has been 

 allowed, which is hardly likely to be the case, as in masonry 

 structures with a live load a factor of safety of 8 is generally 

 recommended ; on the other hand, the ordinary kinds of chalk 

 are capable of resisting a crushing pressure of 330 pounds per 

 square inch. The masonry piers are 190 feet in length at the 

 base, and 140 feet above, the width depending on the columns 

 which they have to support. The distance between the piers is 

 fixed at 1650 and 990 feet, 1155 and 660 feet, and 825 and 

 330 feet, the largest spans corresponding to the greatest depths, 

 and the smaller ones to smaller depths and the parts near the 

 shore. Each supporting pier will consist of a block of masonry 

 of best material, set with Portland cement, and laid on the sea 

 bottom ; the masonry will be built inside metal caissons similar 

 to those used for ordinary bridge piers, and forced by compressed 

 air down to the solid ground. Their surface above hi<^h-water 

 level will form the foundation for the metal columns, which are 

 cylindrical in shape, and vary in height between 132 and 140 feet, 

 and on them are placed the main girders of the bridge. These 

 girders are 200 feet above low-, and 178 feet above high-water 

 level. This height is amply sufficient for the passage of the 

 largest ships. The system of girders proposed to be employed 

 is simple, unlatticed, trussed, so as to insure the proper distribu- 

 tion of all the stresses. After consideration it has been found 

 advisable, instead of forming the 990 and 1650 feet spans of 

 I girders extending over the whole length of 990 feet, and extend- 

 ing on either side in the form of cantilevers of 825 feet, so that 

 ! the junction of the two cantilevers should constitute a span of 

 1650 feet in all, not completely to cover the spans by means of 

 cantilevers, but to connect these by an ordinary independent span, 

 j a saving of 17 per cent, being thus realized in each overhanging 

 j portion of the cantilever. In this manner the 1650-feet span 

 comprises two cantilevers of 619 feet each, and an independent 

 \ span of 412 feet. The metal flooring on the central span and 

 cantilever is formed of tuo girders resting upon two piers 

 990 feet apart, and lengthened on either side to the extent of 

 619 feet. These girders are 36 feet high at the ends of, the 

 overhanging portions, and 214 feet high almost throughout the 

 span of 990 feet. Each girder consists of two chords connected 

 by bracings forming isosceles triangles. The lower ribs of the 

 two girders have a distance of 82 feet between their axes in the 

 central span of 990 feet, and an interval of 33 feet at the ends. 

 The level of the permanent way is 237 feet above low water ; a 

 double set of rails is proposed, and the width of flooring proper 

 will be 26 feet. j 



The paper further gives a detailed description of the foundation 

 work, comprising the situation and dimensions of the piers, the j 

 construction, conveyance, and fitting into position of the support-,' 

 ing columns, and the materials and machinery required for the com- 1 

 pletion of the work ; also the construction, transport, and putting 



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