"Above us a continuous mass of clouds; below us, detached clouds, which seem to roll towards Paris. We feel a fresh breeze. "4h. 13m. Barometer 597-73 mm. attached thermometer+9.° C. Height 2013 metres. "4h. 15m. "4h. 20m. 66 558.70 9. 66 66 66 2567 "The cloud into which we are penetrating presents the appearance of a common very thick fog: we no longer see the earth. "Barometer 405-41 mm. attached thermometer -7°. Height 5121 metres. "Some rays of the sun become perceptible through the clouds. "The barometer oscillates between 366.99 and 386-42; the thermometer -9°; height from 5911 to 5492 metres. "The balloon is completely distended; the tube appended, which up to this time had remained flattened under the pressure of the atmosphere, is now distended, and the gas escapes by its lower orifice, as a whitish streak; we perceive its odor very distinctly. A tear is found in the balloon at the distance of 1.5 metres from the origin of the tube. clearer space shows itself, and allows the position of the sun to be vaguely seen. A "After again throwing over some ballast, the balloon resumes its ascent. "4h. 25m. Barometer oscillates from 347-75 mm. to 367-04; thermometer-10-05 to -98.o; Height 6330-5902 metres. "The mist, much less intense, allows a white and feeble image of the sun to be seen. Barometer oscillating. We are covered with little icicles in extremely fine needles, which collect in the folds of our clothes. During the descending period of the barometric oscillation, that is, during the ascending motion of the balloon, the note-book opened before us receives them so that they appear to fall upon it with a kind of crepitation. Nothing similar shows itself during the ascending period of the barometer, that is during the descent of the ærostat. "The horizontal thermometer with glass bulb gives 4.069. 66 silvered" 66 -8.095. 66 66 "We see distinctly the disk of the sun through the frozen fog, but at the same time, in the same vertical plane, we see a second image of the sun nearly as intense as the first; the two images appear symmetrically placed above and below the horizontal plane of the car, each making an angle of about 30° with this plane. This phenomenon was seen for more than 10 minutes. "The temperature falls very rapidly; we attempt to make a complete series of observations upon the thermometer for radiation, and on the thermometers of the psychrometer, but the mercurial columns are hidden by the corks, because so sudden a fall of the temperature had not been foreseen. The thermometer with the coverings of tin plate gives -23.079. "4h. 32m. The clouds separate above us, and we see a place in the sky of a light azure blue, like that which on a clear day is seen from the earth. The polariscope shows no polarization in any direction on the clouds, in contact with us, or farther off. The sky-blue is, on the conVOL. XXI.-THIRD SERIES.-No. 1.-JANUARY, 1851. trary, strongly polarized. Barometer oscillates. Ballast thrown out, by which a new ascending movement is obtained. "4h. 45m. Barometer 338.05 mm. attached thermometer -35°. Height=6512 metres. "Our fingers are stiffened with the cold, but we experience no pain in the ears, and the respiration is not at all obstructed. The sky is again covered with clouds, but the clouded sun and its image are still visible. We throw out ballast, which gives a new ascent. "4h. 50m. Barometer 315-02. The extremity of the attached thermometer is about 2° below the lowest division traced on the instrument. This division is-37°; the temperature was then about -39°; height 7016 metres. "The barometer oscillates from 315.02 to 326-20; thus the ærostat oscillates from 7016 to 6765 metres. We have but 4 kilogrammes of ballast left, which we deem prudent to keep for our descent. We hoped to keep ourselves for some time at this height, but although the silk tube was raised up to avoid the exit of gas from its orifice, the balloon begins its descent. We take the air for examination. The tube of one of the globes is broken by the efforts made by us to turn the stop-cock. The second is filled with air without accident. "5h. 2m. Barometer 436-4; temperature -9°. Height 4502 metres. "We again meet the little needles of ice. "These oscillations were produced by the last portions of our ballast which we threw out. We think of nothing but moderating our descent by sacrificing every thing disposable except the instruments, and we put the thermometers in their cases. "5h. 30m. Reached the earth, at the hamlet des Peux; commune de Saint Denis-les-Rebais; arrondissement de Coulommiers, (Seine et Marne,) a short distance from the residence of M. Brulfert, the Mayor of this commune, situated 70 kilometres (43 miles) from Paris. We were so fortunate as not to break any of the instruments in the descent. We found at the village nothing but a cart to carry us to the nearest station of the Strasburg railroad, which is 18 kilometres (11.18 miles) distant. The journey was a severe one over the cross-roads; the horse fell. Two of the pieces of apparatus which we were the most desirous of bringing back to Paris unhurt were broken, or rendered valueless; the globe of air, and the instrument which indicated the minimum barometric pressure. Happily the minimum thermometer of M. Walferdin was brought back with its seal unhurt, to the College of France. "The seal was removed by MM. Regnault and Walferdin, and the minimum temperature, determined by direct experiments, was found -39-67, consequently differing very little from the lowest temperature which we ourselves had observed on the thermometer attached to the barometer. "At the request of M. Regnault, MM. Person at Besançon; de Breauté at Dieppe; Bertin at Strasburg; Hoghens at Versailles; Monod at Orleans; Renou at Vendôme; Malaguti at Rennes; Girardin and Bouton at Rouen; and Isidore Pierre at Caen, made, during the 26th and 27th July, barometric and thermometric observations every quarter of an hour." For the Journal of the Franklin Institute. Steam on the Upper Danube. In some high pressure steamers, recently fitted out at Munich, by Mr. Joseph Hall, for boats navigating the Upper Danube, there is an arrangement which may be considered an improvement, and which might be made available on our western waters. Attached to the cylinder is one valve for the admission of steam, and two for its escape; the former is worked in the usual way, but the latter are made to work as follows: the exhaust valve communicating with the atmosphere, opens when the piston is 13 inches from the end of the cylinder, and continues open until the piston has completed its full stroke, and has come back 13 inches, when the first exhaust valve is closed, and the second, communicating with a condenser, is opened, and the steam remaining in the cylinder is condensed in the usual way. B. Translated for the Journal of the Franklin Institute. Experiments on the Thermo-Electric Power of Crystallized Bismuth and Antimony. Extract from a note by M. SVANBERG, communicated by M. REGNAULT. For some time past the observation of facts which it is useless to mention here, had led me to think that the thermo-electric force of the metals might probably depend on some variability in their conducting power for electricity. I was, moreover, led to believe that this conducting power ought to be variable in different directions in crystallized bismuth and antimony, since their crystalline form, according to the recent examinations of MM. Faraday and G. Rose, does not belong to the regular system. I was hence led to examine whether the thermo-electric power of these two metals would not also be variable with the direction. This supposition has been completely verified by the experiments which I am about to describe. In large masses of bismuth or antimony the crystalline texture is never the same throughout, but it is not difficult to find homogeneous parts in them. Then with a saw we may form little bars whose length shall be differently inclined to their planes of crystallization. Among the planes of cleavage of these two metals in the crystalline state, there is one, noticed first by M. Faraday, which differs from the others by greater brilliancy. This plane is perpendicular to the principal axis of crystallization. Among the other planes of cleavage there is one whose brilliancy is not much inferior to that of the preceding. I shall call (A) the bar whose length coincides with the intersection of these two planes; by (B) I shall designate the bar whose length is perpendicular to the most brilliant cleavage-plane. Antimony and Bismuth have this common property-the bars (A) are more positive, and those (B) more negative, in the thermo-electric series, than any other bar which can be formed from the same metal. The thermo-electric force between the Antimony (A) and (B), or between the Bismuth (A) and (B), is quite considerable. If a bar is taken intermediate between (A) and (B), that is to say, so that the direction of the length is differently inclined to the plane of cleavage, or if it has not a regular crystalline texture, it is negative with (A) and positive with (B). It will be seen that the direction of the length of the bars (B) agrees with the magne-crystalline axis of M. Faraday, as has been tried and confirmed for every bar employed. This axis took the axial position in Bismuth, and the equatorial for Antimony, which accords with the observations of M. Plücker. This variability of the thermo-electric force of Bismuth and Antimony appears to give the key for the explanation of the currents observed by MM. Sturgeon and Matteucci, in circuits formed with only one of these metals. Heretofore they have not been explicable. As to the direction of the thermo-electric currents between hot bismuth and cold bismuth, or hot antimony and cold antimony, different experimenters have obtained different results. Vorselmann de Heer, who is the last who has attended to this subject, found that the current went sometimes from the cold metal to the hot, sometimes from the hot to the cold. He believed, from his observations, that the direction of the current depended on the greater or less difference between the temperatures of the bars. He says that he found these reversals particularly with antimony. In order that such experiments shall have any value it is absolutely necessary that the bars operated on shall hold the same place in the thermo-electric series. Thus, for example, (A) must be compared with (A) and (B) with (B), but not (A) with (B). It ought, therefore, to have been first ascertained whether the two bars are absolutely homogeneous. It is very remarkable that (A) with (A) does not behave in the same way as (B) with (B). My mode of experimenting was as follows: The two bars were fixed in copper handles, which by wires also of copper, were put into communication with a very sensitive galvanometer. From the points of contact with the copper, the bars were immersed in snow nearly to their free extremities; in this way no current could be excited by bringing the extremities in contact, and giving them any elevated temperature. This is the method of ascertaining satisfactorily that the bars are thermo-electrically homogeneous. But if, before putting them in contact, the extremity of one of the bars be slightly either heated or cooled, a current is established, whose direction the galvanometer indicates. If the two bars are of Bismuth (A) or Antimony (A), the current passes from the cold metal to the warm; if the bars (B) are operated on, the direction is opposite: that is, the current goes from the warm to the cold metal. This difference between (A) and (B) appears to me to be very remarkable, but I have verified it by multiplied experiments with different bars. I have never been able, in my mode of operating, to find any reversal of the current when the difference between the temperatures of the two extremities was increased. For slight differences of temperature, M. Vorselmann de Heer found, while experimenting on Antimony, the current going from the warm to the cold metal. The opposite direction, which I found for the Antimony (A), cannot be explained by any slight elevation of temperature which might have been communicated from the heated end to the point of junction with the copper; for it is easy to see that such a warming would have produced a precisely opposite effect. But it is very possible that M. Vorselmann de Heer may have experimented with bars thermo-electrically heterogeneous, a very excusable inadvertence, since the connexion between the thermo-electric force and the direction of the current, relative to the plane of crystallization, was not then known. For Bismuth (B) I found, as did the experimenters who have made. the experiment before me, that the current passed from the warm metal to the cold. The opposite direction which I have observed for Bismuth (A) cannot either be explained by any slight elevation of temperature, which might have been communicated from the heated end to its point of junction with the copper, since an opposite effect would thus have been produced.—Comptes Rendus de l'Acad. des Sci., Aug. 19, 1850. For the Journal of the Franklin Institute. Screw Propellers. Cannot the Institute throw some real practical light on this subject, viz: What is the best form of propeller? Should it have 6, 4, 3, or 2 blades? Which is the best angle? Should they be run at high or low speed? There are at least a dozen different patents, but none of them settle these points. What proportion should the propelling surface of the propeller bear to the immersed midship section of the vessel? At present, scarcely any two propellers are built alike; constant changes are made without apparently affecting the result. Are they all right, or all wrong? H. English and American Steamship Building.—Ocean Navigation.--The Cunard and Collins Lines.* Sir, -The publication of certain facts and drawings, in Nos. 1398 and 1408, relative to the rival steam-ships of the Cunard and Collins' Transatlantic Lines, induce me to address you as heretofore, under the same signature, which, though anonymous, shall, I trust, be supported by facts and figures sufficient to neutralize that disadvantage. And I may state my reasons for this course. I do not wish to make your pages a vehicle for personal renown or professional advancement. I shall rigidly adhere to the truth, to the best of my belief, and utterly repudiate any personal allusions or antipathies. I should prefer to remain unknown; but I authorize you to give up my name to any one who, in your judgment, may require it for proper purposes. * From the London Mechanics' Magazine, for September, 1850. |