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THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[October, 



not only according to the external temperature, but also in the different por- 

 tions of the plants. This he attributes to the flow of the sap, which, having 

 received the vital heat from the direct action of the sun's rays, carries it as 

 it flows ; consequently, the portions immediately under the influence of the 

 sap have a higher degree of temperature than those which are most distant. 



Another report was made to the Academy, on the cjiirass of cotton felt, as 

 a means of defence in war. In the first report to the Academy, the con- 

 clusions of the commission were not altogether favourable ; for, although it 

 was admitted that the cuirass resisted the action of pistol balls, it bore traces 

 of injury from the concussion to which it was exposed. In the present 

 instance, it appears that the cuirass was exposed to a severe test, by being 

 fired at with cavalry pistols, at the distance of a few paces, and that it 

 effectually resisted the balls. 



July 25. — A paper was read by M. Vallee, " On ttie mode of rendering tfie 

 Lake of Geneva subsidiary to tlie Rhone." Amongst the phenomena pre- 

 sented by the Lake of Geneva is one which has particularly attracted the 

 attention of M. Vallee, viz. the sudden changes of level which in the country 

 are called se'ches. He attempts to account for this phenomenon by supposing 

 the existence of a subterranean lake, communicating on the one side with the 

 Leman, and on the other with the high valleys by means of natural wells, 

 which are nearly vertical. In this way he endeavours to explain the rising 

 and falling of the waters at Geneva, which have been frequently noticed to 

 vary as much as two metres at a time, and to account for the rapid and ex- 

 tensive changes which occur in the temperature of the lake. 



August 1. — M. Bessel, of Kocnigsberg, and Professor Erman, of Berlin, 

 were present. Each read in French a communication to the Academy. 

 The paper by M. Bessel was on the laws of atmospheric refraction as con- 

 nected with astronomical observations. The paper by Prof. Erman was a 

 report on a meteorological voyage of circumnavigation. In the course of 

 M. Erman's expedition round the world, the vessel in which he was, passed 

 four times from latitude 50' north to 58' south, and during this transition 

 M. Erman made observations with the barometer six times a- day. He states 

 from them that, in general, the pressure on the barometer goes on 

 diminishing very slowly from the equator to the poles, and what proves that 

 this depends on the general constitution of the atmosphere, is the fact that 

 the diminution is constant and regular. Thus in the waters of Cape Horn, 

 as well as on the coasts of Kamscbatka, the mean height of the barometer 

 is twelve millimetres lower than the mean height of the great equinoctial 

 ocean. Hence it follows, says M. Erman, that the pressure of the air is not 

 the same on basins of the same level in vast seas. M. Erman concludes, 

 from the result of his observations, that a hope may now be reasonably en- 

 tertained of becoming fully acquainted with the general law of the distri- 

 bution of the air over the surface of the globe, so far as that law may appear 

 to depend on pressure. 



A report was read by M. Dufrenoy, on a coniniunieation from M. Araedee 

 Burat, respecting the position of the coal veins in the basin of the Saone-et- 

 Loire. The veins are not in strata, and they exceed in thickness all others 

 known, but the veins are less continuous than in other coal districts in their 

 direction and inclination, are mLxed with clay, and he concludes that they 

 have been formed by a vegetation on the spot, periodically destroyed by the 

 rising of the neighbouring waters beyond their ordinary level. 



Aug. 8. — M. Arago gave an analysis of a paper by M. de Ruolz, on the 

 means of f. ring one metal upon another by the galvanic process. When the 

 first paper of M. de Ruolz, on this subject, was read, the practical use of the 

 discovery had gone no further than the precipitation of pure metals, and it 

 remained to be ascertained whether mixed metals could be precipitated. 

 This M. de Ruolz has done, and several specimens covered with a precipitate 

 of copper and tin, in the proportions which constitute bronze, were submitted 

 to the Academy. The red tint of copper, so offensive to the eye in objects 

 of art produced by the galvanic process, has given place to the more delicate 

 and pleasing appearance of bronze. The various advantages of the galvanic 

 system are fully shown in the paper of M. de Ruolz. A precipitated coating 

 must always be more regular and uniform than one laid on by hand. It can 

 be made to any degree of thickness, and cannot be detached from the mate- 

 rial to which it is appUed. Iron roofs, for instance, both as to frame-work 

 and sheet-iron, may be coated so as to resist the action of the atmosphere, 

 and this without any great augmentation of cost, for the coating may he 

 thin, and the iron work itself, not being exposed to atmospheric action, may 

 be made much lighter. For domestic purposes, the galvanic process as regards 

 a leaden envelope, may be advantageously employed in various ways, and M. 

 de Ruolz suggests that it would be well to employ it for iron shot, which 

 undergoes great deterioration from exposure to the atmosphere. 



A letter was read from M. Agassiz, who has been for some time encamped 

 on the summit of the Aar, for the purpose of studying the phenomena of 

 the glaciers. He writes that the mass of ice in that part advances towards 

 the valley at the rate of 220 feet annually, and the surface loses 7 feet of ice 

 every year, which loss, however, finds its compensation in the infiltrations 

 which become frozen, and raise the base. 



Aug. 15. — M. Dumas placed before the Academy some specimens of the 

 power of the newly-invented roller, by M. Schatteamann, which, according 

 to a former report, has been used with great effect in compressing together 

 into one solid mass the fractured portions of the stones used for macadamizing 

 roads. The specimens now submitted to the Academy are of two kinds. In 



the one the interstices of stone are filled with sand, so compressed as to be- 

 come as solid as the stone itself; in the other, fragments of stone are rolled 

 together, and form the most complete cohesion. 



Aug. 29. — A further communication was read from M. Agassiz. M. Agas- 

 siz informs the Academy that he has ascertained that the glacier is throughout 

 mined and sapped by watercourses, as he was convinced, from experiments 

 which he had before performed, and of which he had given an account, that 

 ice is porous in a high degree, and that the motion of glaciers is due in part 

 to the infiltrations of water through the mass, thus imdermining the base ; 

 and that the experiments on the glacier of the Aar have established the truth 

 of this theory. M. Agassiz also mentions a fact which tends to corroborate 

 what has been stated as to the phosphorescence of clouds. He mentions 

 that it is more easy, on the glaciers at night, to distinguish the hands of a 

 watch when the sky is covered with clouds, than when it is cloudless and 

 the light of the stars is seen. He also states that the appearance of a peculiar 

 snow, well known to all visitors of the glaciers, is not a snow that falls, but 

 merely a modification of the frozen surface. 



In a paper lately read on some remarkable circumstances connected with 

 the Daguerreotype, it was stated that a cameo having been suspended so as 

 to hang near, but not to touch, a polished plate in a box from which all 

 light was excluded, the engraving of the cameo was clearly and distinctly 

 marked on the plate. M. Breguet,the celebrated watchmaker, has addressed 

 a letter to the Academy, in which he states that he has frequently seen, on 

 the polished inner surface of the gold cases of his flat watches, the name of 

 his house plainly and legibly marked, the impression having been received 

 from the engraved letters of the covering of the works, which did not touch 

 the case. 



Sept. 5. — A communication was read from M. Valle, a colour-maker, on 

 the employment of a solution of caoutchouc for canvas used by painters. M. 

 Valle was led to the researches which have terminated in the invention which 

 he has submitted to the Academy, by observing the injury caused to the 

 works of some of the greatest masters by the influence of the atmosphere 

 upon the canvas. M. Valle's method of preparing the solution is at present 

 a secret. Although applied to both sides of the canvas, it leaves it sufficiently 

 elastic to prevent cracking, and secures it against the action of the atmos- 

 phere. To this discovery he adds that of a peculiar kind of varnish for the 

 painting, and thus he defies the ravages of time. 



The subject of the meteors commonly called sliooting or falling stars, was 

 alluded to. According to the last communications from M. Arago, the period 

 between the 10th and 12th of August still retains a marked superiority for 

 this phenomenon, which is still so little understood. M. Littrow, of Vienna, 

 counted, on the night of the 10th of August, 129 of these meteors per hour. 

 On the same night M. Bonard, of Rennes, counted 44 per hour ; at Tours, 

 and in the department of the Doubs, M. Laugier and M. Mauvais witnessed 

 a shower of these meteors. At Paris and at Toulouse the observations of 

 M. Eugene Bouvard and M. Petit were attended with less marked results, 

 but still they were sufiicient to prove that the period of the year above named 

 is that in which the phenomenon abounds. In a commuuication to the 

 Academy, M. Bourdot, of Grand-Lemps, in the Isere, states that he watched 

 with great attention the passage of these meteors on the night of the llth 

 ult. In no instance, when they exploded, did he hear any noise, but the 

 explosion was, in several instances, followed bv a long train of phosphoric 

 light. 



INSTITUTION OF CIVIL ENGINEERS. 

 Aiml 26. — The President in the Chair. 



" A description of a netv arrangement for raising S/iips of all classes out 

 of water for repair, proposed to replace the Graving Dock or tlie Patent 

 Slip in certain situations ; with observations upon tlie other metliods used al 

 different periods for t Ids purpose." By Robert Mallet, M. Inst. C. E. 



This communication describes an apparatus proposed by the author as a 

 substitute for the graving dock or the patent shp, in situations where such 

 constructions would be too expensive, or an inappropriate locality prevents 

 their adoption. It reviews the principal methods hitherto in use— such as 

 stranding by bilge-ways, careening or beeUng over, lifting by the camel, the 

 graving dock, the floating dock or caissoou, the screw and the hydraulic 

 docks (both American inventions), and Morton's patent slip ; it euumerates 

 the localities for which each of these inventions is most applicable, and then 

 gives the objections to them. The author then describes the general prin- 

 ciple of his invention to be, the diffusion of the load or strain over the great- 

 est possible number of fixed points, avoiding casual and unequal strains ; that 

 there should be uniform motion, with a power proportioned to the resistance. 

 In providing for this, the joggle-joint is used throughout. The machine con- 

 sists of a platform, supported upon a series of frames with joints at each end, 

 attached at the lower extremities to fixed points in the foundation, and at 

 the upper ends to the under side of the platform, which is traversed by a 

 series of beams, to the ends of which are fastened rods coimected with rollers, 

 working in grooves along a suspended railway on the cantilevers of two 



