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under as well as over the wear, carrying with it, of course, the silt, which would otherwise accumulate in the bed of the river. The paper gave rise to a short discussion, in the course of which Sir M. I. Brunel, F.R.S., and Mr. Fairbairn, civil engineer, expressed their approbation of the principle, and the former thought it highly worthy of a trial.

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Ventilation of Dwelling-Houses and Public Buildings. - Mr. Andrew Liddell, of Glasgow, read a paper on a mode of ventilation adopted under the direction of Mr. Fleming, a surgeon, of Glasgow, in different public and private buildings, in and near that city; one of them a large building, four stories high and occupied by a considerable number of the poorest families. This mode of ventilation, which consisted in drawing of the foul air from each room by a pipe leading to the chimney of a steam engine, had been attended with the most beneficial results as regarded the health of the inmates, and paticurlarly by a great diminution in the mumber of fever cases. similar plan has also been applied, with the best results, to the cabins of the Princess Royal steamer, which plies between Glasgow and Liverpool. Sir John Robinson observed, that it was highly satisfactory to find sound principles in regard to ventilation, making their way amongst the people of this country; but it was at the same time to be regretted, that ineffective plans should be resorted to, when the very best plans had been many years before the public. The mode of ventilating the Derby Infirmary, devised by Mr. Strutt, and published by Mr. Silvester more than twenty years ago, had exhausted the subject of ventillation; and since that time nothing new had been invented, nor had any real improvement upon Mr. Strutt's plans been devised by anybody.

On Fractures of the Axles of Locomotive Engines.-Mr. Vignolles read a paper, the object of which, he stated was to fix the attention of the scientific engineers and manufacturers of Manchester on certain circumstances connected with the late frightful accident on the Paris and Versailles Railway, originally caused by the breaking of one of the axles of an engine. After some remarks on the identity of the circumstances under which the accidents had occurred on the Paris and Versailles, and the Brighton lines, glancing at the much disputed question of the relative merits of four and six-wheeled engines, and pointing out the precautions which should be adopted in forging axles for railway engines and carriages, the paper statedthat some of the French engineers had suggested that the source of the often unexplained breaking of axles on railways must be looked for in another quarter than the mere quality of the iron of which they were composed, or the care which had been bestowed upon its fabrication. M. François and Colonel Aubert, who had both read papers at the Royal Academy of Paris, on the subject of the late accident, attributed the fracture of the axle to the iron having become crystallized by the heat or magnetism, arising from the severe strains and blows to which it was exposed. In support of

this opinion, they stated that the axle was formed of the very best iron, and was of sufficient dimensions; but that the fracture exhibited a decidedly crystalline appearance. M. François stated in his paper, that he had made a long continued series of experiments, and had observed that a magnetic action on iron, in a state of fusion, would produce similar effects, and change the small and closely adhering particles into coarse and large crystals, depriving the iron of its compact character. He therefore inferred, that the action of heat or of percussion on the axles of railway engines, when moving at high velocities, might produce a magnetic action which would be attended with the same results. Both M. François and Colonel Aubert, seemed to be of opinion, that the only effective precaution was to change the axles of locomotive engines so frequently as not to give them time to undergo this crystalline change. In seeming corroboration of the opinions of these distinguished French engineers, Mr. Fairbairn had stated to him (Mr. Vignolles) that cold swaging of hammered iron would cause it to assume a crystalline form; and, if so, the shocks which the axles receive during rapid transit, might easily operate in producing this remarkable change of texture. Although this reference to the supposed change in texture of iron constituted, in our judgment, the most interesting portion of the paper, it contained, as we have already intimated, a number of other points of considerable importance. This paper gave rise to a long, animated, and most interesting discussion, but of a character so diversified and desultory as to forbid any attempt at a detailed or consecutive report. We shall, therefore, omit such portions of it as related to the comparative merits of cranked and straight driving axles, and of four and six-wheeled engines, and confine ourselves to an abridgment of what was said on the important point suggested by the papers of the French engineers. On this point Sir Mark Brunel said, that he had been involved in a railway accident at Rugby, in which two or three axles were broken, and he had observed that the fractures exhibited a crystalline appearance, more like that of cast than of wrought iron. Mr. Hodgkinson said that some of his experiments on cast iron tended to show that a force which would produce a very slight deflection in a long bar, would to some extent impair its elasticity, and prevent it from resuming its former shape, which seemed to show that there was some change in its internal structure. His experiments were certainly made upon cast iron; but he had reason to believe that the same results would be experienced with respect to wrought iron.Mr. Fairbairn observed, that it was a fact well known, that if iron bars were swaged below a blood-red heat, the iron would become crystalline, however fibrous and ductile it might previously have been. Mr. Hawkins said that at a recent meeting of the Society of Civil Engineers, a very interesting paper had been read on this subject, and numerous speecimns of fractured iron had been exhibited, which, though undoubtedly fibrous originally, had become decidedly

crystalline by use.-Sir M. Brunel observed, that any one who considers the ordinary motion of a railway engine or carriage, at a high rate of velocity, would see that the axle must receive an immense number of blows like blows upon an anvil, and which would probably have the same effect upon the texture of the iron. Mr. Jeremiah Garnet said it was well known that violent hammering or friction rendered iron magnetic, causing it to attract iron filings very freely; and it would probably be found that in all such cases there was some change in its molecular arrangement, similar to that described in railway axles.-Mr. James Nasmyth confirmed Mr. Fairbairn's statement, as to the injurious effects of swaging or hammering iron when nearly cold; and suggested that the only safe course was to have all axles annealed after forging, by which the injurious effects of injudicious workmanship would be entirely got rid of. The Chairman enquired whether Mr. Nasmyth supposed that annealing would remove the crystalline texture resulting from use, and restore the fibrous texture of the iron. Mr. Nasmyth said he had no doubt it would have that effect. He then made some very interesting observations on the absence of oxidation from those iron rails of railways on which the traffic was only in one direction, and observed that on the Blackwall line, where the trains travelled backward and forward on the same line, the extent of oxidation was very striking. After some further discussion, in which Sir John Robinson, Mr. Grantham, Mr. Lucas, Mr. Burdekin, and several other gentlemen took part, there was a pretty unanimous expression of opinion, that the subject was one well deserving investigation; and that the funds of the British Association could not be better employed than in defraying the expense of a series of experiments on a point so interesting to scientific men, and so important to the public; and Mr. Vignolles expressed a hope that next Monday would not be permitted to pass over without a motion for a grant for that purpose. At the conclusion of this discussion, the Chairman said he thought it would be quite useless to attempt to fix the attention of the section on any other subject, and he therefore proposed to adjourn to the following day; which was acceded to, and the section broke up.

THE FIRST GENERAL MEETING OF THE ASSOCIATION.

As was previously announced, this the first general assemblage of the members of the association at their twelfth meeting took place on Thursday evening last, in the spacious meeting-house of the Society of Friends, Mount-street, which, it is said, will contain about 2,000 persons. It was considerably more than half-filled, and a very great number of ladies were present. The assembly was indeed in every respect a most brilliant one, and the greatest interest appeared to prevail throughout the proceedings, notwithstanding the period of time which they occupied, and the comparatively late hour of the evening at which they commenced.

On the "preacher's gallery" were the presidents, retiring and elect, Roderick Impey Murchison, Esq., and Lord Francis Egerton, M.P., the Marquis of Northampton, Sir David Brewster, Sir John Herschel, Rev. Professor Whewell, General Sir Thomas Brisbane, Sir J. Robinson, Colonel Sabine, the Rev. Dr. Peacock, Dean of Ely; the Rev. Professor Powell, Professor Willis, Dr. Dalton, Dr. Turner, Sir H. T. de la Beche, the Hon. and Very Rev. Dr. Herbert, Dean of Manchester; the Rev. Richard Parkinson, B.D., Canon of Manchester; Colonel Sykes, the Rev. William Vernon Harcourt, Sir William Jardine, John Scott Russell, Esq.; Professor Sedgwick, Sir Charles Lemon, Dr. Richardson, Sir M. I. Brunel, Sir Oswald Mosley, Henry Hallam, Esq., F.R.S.; George William Wood, Esq., M.P.; Rev. Dr. Halley, Colonel Wemyss, Mr. Griffiths, Surveyor General of Ireland; Colonel Pringle, R.E.; George Webbe Hall, Esq.; R. D. Davenport, Esq., of Capesthorne; John Taylor, Esq., Treasurer of the Association; Professor Phillips, General Assistant Secretary; &c. The seats immediately in front of and below the gallery were reserved for the committee of the association.

At twenty minutes past eight o'clock, the retiring president of the association, the Rev. Professor Whewell, F.R.S., &c., took the chair, amidst great applause; and proceeded to open the business of the meeting. He said it was not necessary that he should announce to any one present, that this was the twelfth meeting of the British Association, or that this was the first day of that meeting; on which, according to the custom observed on former occasions, it was the rule that the president and the other officers of the association should appear before the assembled members. His position here was that of an individual who held the high office of president; but his business in that capacity was very brief: it was merely that of surrendering the cares and duties of his office into the hands of his successor. It might perhaps appear an anomaly to some, that he should continue, not only to act as chairman, after the appointment of his successor, but even after the business of the present meeting of the association had begun; those, however, who knew anything of the mode in which their proceedings had been conducted on former occasions would be aware of the circumstances which led to that arrangement. On the first day of their assembling, many members from a distance did not arrive early in the day, so that the general meeting could not be held till the evening; yet as it was not deemed advisable to lose a day in waiting for the arrival of all the members, the various sections were accustomed to meet for the transaction of business; and he had much pleasure in announcing that the whole of the various sections had already been most actively engaged, and that they had got through a great deal of business. His duty now, however, was very brief and simple. It was merely to hand to his successor the torch of knowledge; which you commit to us (said the chairman), which we hand to one another, and which derives all its powers of illumination

from your exertions and your talents.

I have often thought, in see

ing this office transmitted in this manner, from one to another, in having unexpectedly received it myself, and in now transmitting it to my successor, I might say, in the words of the poet

"Et quasi cursores vitaï lampada tradunt,"

which I may alter to

"Et quasi cursores musarum lampada tradunt," which, if you will allow me to offer a translation, as ladies are present, I would say

"As in the torch-light of the Grecian youth,

We pass from hand to hand the lamp of truth."—(Applause). As he had now filled all the various offices of the association, it was impossible that he should not look with no small degree of interest to its future fortunes. It was impossible that he sould not feel some anxiety in glancing into its future, that he should not wish to know in what respect it might resemble or might differ from the past. During the period which had elapsed since the formation of the British Association, it had successively visited York, Oxford, Dublin, Cambridge, Edinburgh, Bristol, Liverpool, Newcastle, Birmingham, Glasgow, Plymouth-great cities, powerful and opulent, among the greatest in the empire-and it is now held in Manchester, inferior in these respects, we might say, to none. (Applause). In this manner, the British Association had gone through a great number of the most prominent and distinguished towns in the empire; and as long as the association came to such places, its members were sure to find persons who would share in and take an interest in their labours. An abundant number of persons would be found ready to engage in those laborious offices which were necessarily connected with the preparations for the reception of the association, and the rendering of their proceedings agreeable and useful. And when the association left this town for another, they would go with a feeling which he ventured to express, on dissolving the last meeting at Plymouth, "To-morrow to fresh fields, and pastures new." But the number of towns so circumstanced in the empire was limited; and if they looked forward to the time when such pastures began to fail - when there were no opulent cities able thus to receive us, which were not visited before, the association were naturally led to enquire what was the course it should then take. It appeared to him, that there were three courses open to them. After visiting all the great towns, the association might then go to towns of a smaller size, which might derive their power of receiving them not only from themselves, but from those districts which they represented; or the association might return to those towns in which they had already held their meetings; or it might be found convenient to suspend the proceedings of the association, and look forward to some future course. He wished it to be understood, that in making these observations, he spoke as an individual, and without the sanction of any official persons. He trusted that his views, thus

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