"Twenty-seven years after Goethe had been left in the rear as a naturalist, or rather forgotten under the title, his day of triumph arrived. De Candolle appeared with the rich booty he had collected during his admirable researches into the teratology of vegetables. De Candolle, who had passed through every grade of botanical knowledge, adopted, under a slightly-different form, the notions of the great poet on the analogy of organization, and immediately afterwards determined to visit, at Weimar, the illustrious old man who had enunciated these excellent ideal preconceptions in the science. There, cordially congratulating the philosopher, so tardily admitted to the title, he beheld in him a real naturalist, in the midst of a valuable cabinet of natural history, and occupied in observations upon living beings!"-GEOFFROY SAINT-HILAIRE. Grand Scientific Survey, by order of the Russian Government. A SCIENTIFIC expedition for the purpose of accurately determining the long-disputed question of the levels of the Caspian and Black Seas, was to commence its operations in July last. The government of Russia has undertaken it on the suggestion of the Imperial Academy of Sciences, at St. Petersburgh. It has approved of the plan of operations drawn up by the Academy, and munificently placed 8000l. at their disposal to defray the expenses. The details of the organization of this expedition, and the selection of the scientific corps who are to carry its operations into effect, have been confided to Professor Struve, the astronomer of Dorpat. He has appointed three of his former pupils; Hr. George Fuss, assistant-astronomer of the Central Observatory, and who has given evidence of his ability by his labours in China and in the south-east of Siberia; Hr. Sabler, assistant-astronomer of the University of Dorpat; and Hr. Savicht, Professor of Mathematical Sciences in the University of Moscow. These are accompanied by a mechanician, and furnished with a complete selection of the necessary instruments. The time required for the operations is estimated at about eighteen months. The line of this vertical survey is to be conducted trigonometrically, and will be run, according to local circumstances, either between Taganrog and the mouth of the Kouma, along the Manitch, and across the steppe, or between Taman and Kisliar, following the range of the Caucasus. Simultaneous barometrical observations, with instruments regularly compared, will be made, not only by the travellers along the line of operation, but also at Astracan and at Taganrog, by experienced and confidential persons stationed in those towns. Mirage in Iceland. 'WE have had very often the phenomenon of the mirage under observation; and, contrary to the opinion of some navigators who have visited the North, I was never able to remark that objects were elevated by it. It always appeared to me like a bright fog on the surface of the sea, which, variously modifying the bases of objects, might, I believe, in certain circumstances, so influence the illusion, as to give an idea of their being elevated by the phenomenon."ROBERT. Letter from Iceland, July, 1836. When this extract was read in the Académie des Sciences, M. Libri remarked, that it could not be affirmed, as M. Robert appeared to do, that objects were not elevated by the mirage, for this phenomenon, which takes place under very different circumstances, produces very varied effects. In the sandy countries of the south, lakes and sheets of water are seen during the mirage, while in the north and at sea, it is very distant objects only, and even those below the horizon, that are visible. As to whether these objects shall be seen elevated, more or less, by the effect of of the mirage, that will principally depend upon local circumstances, and the state of the atmospheric strata through which the rays must pass which emanate from the objects affected by the phenomenon. Extemporaneous malleable Platinum. "THE process of Wollaston for the manufacture of platinum is made use of by those persons only who manufacture this metal for commerce. Chemists never prepare malleable platinum for the uses of the laboratory, and the process is described in no public course of instruction. Hr. Liebig is, I believe, the only person who in his lectures teaches it. Though the mode he follows is exactly, in every respect, that of Wollaston, and though it presents nothing new in a scientific point of view, I nevertheless am of opinion that I shall perform a useful and agreeable office to chemists, in directing their attention to a process far too much neglected, and so easy of execution, that one may say there is really no operation whatever more simple, or more expeditious, than that of making malleable platinum in the following little apparatus. "It is a hollow cylinder, slightly conical, one end of which is closed by a small thick metallic plate. After having decomposed, at the lowest possible temperature, the ammoniacal muriate of platinum, the froth produced is to be removed by a wooden rod, and mixed with water; after being made into a clear paste it is to be introduced into the cylinder; then, by means of an iron piston, it is to be slightly pressed for one or two minutes; this is to be followed by the greatest possible compression. A ring of iron in which the cylinder stands, permits the easy disengagement of the bit of platinum, by striking a blow on the piston. "The platinum, when thus removed, will be found to have already acquired great density, and a brilliant metallic aspect. It should be dried gently, and afterwards exposed for a quarter of an hour to a white heat, then be suddenly withdrawn from the crucible, and struck once with a hammer. It is to be so treated four or five times, gradually augmenting the number of blows. "In less than half an hour the whole operation is finished, and is so easy, that the result is always certain. "I offer for the examination of the Academy a spatula and a knife-blade of platinum, which I saw manufactured, in a few minutes, in the laboratory of Hr. Liebig, at Giessen."-PELOUSE. Geological Hebrew. IN sawing through a block of marble, Motion of Water on Heated Surfaces. PHYSICIENS have long remarked the phenomenon which water presents when thrown upon a metallic surface heated to a very high temperature. If a small quantity of water be thrown into a crucible of platinum at nearly a white heat, for instance, the drops will be seen to be tossed about from one side to the other of the crucible, or to spin round on themselves, but always continuing a very long time, though their evaporation would have been rapid, had the metal been less hot. M. Baudrimont has concluded, from experiments made with a view to explain the phenomenon, that the drops of water so moving at the bottom of an incandescent crucible, have a temperature much below that of ebullition, and that it never exceeds 122° Fahr. M. Laurent, in repeating these experiments, obtained very different results; according to him, the water, notwithstanding the slowness with which it evaporates, has a temperature approaching very nearly to 212o. M. Laurent also does not admit, that the drops, during the whole time of their existence, are separated from the bottom of the crucible by a thin sheet of vapour; he believes that, on the contrary, they leap continually, and that at each of these bounds they touch the incandescent surface, though for a very short time only. During these movements they present a singular appearance; their outline, instead of being circular, has projections more or less in number, but always of an even number. "It is in the following way," says M. Laurent, "that the generation of these forms may be understood. Let us suppose an elastic circle suddenly compressed in two points, diametrically opposed to each other; it will take the form of an ellipse; but if the compressing cause be suddenly annihilated, the ellipse, by its elasticity, will return to the previous circular form, and, by virtue of the velocity acquired, will not stop there, but proceed to form a second ellipse, the greater axis of which will be perpendicular to that of the first. Thus there will succeed a series of oscillations which will give ellipses whose greater axes are alternatively perpendicular to each other, and, if the movement be very rapid, the impression of a previous ellipse will remain on the retina, when that of a succeeding one is produced upon it, and the two images will be superposed in such a manner, that they will exhibit a cross with rounded ends, or a wheel with four teeth. If the images of the two extreme ellipses, and that of their mean circle, be seen at the same time, a star of eight points will be produced, &c. It is easy from this to see why the number of projections of the figure should always be of an even number. "That which has been said of a circle will hold of a sphere, if it be elastic, as is the water-drop on the floor of an incandescent crucible. "I convinced myself that these forms were owing to vibratory motion, by the following experiment. I placed in a porcelain cup about an ounce of mercury; I set the cup on an elastic board, which I made to vibrate with a violin-bow. The mercury presented immediately the same figures as the water in the heated crucible." Instantaneous Calculation of Areas. M. GAETANO CAÏRO has invented an instrument, to which he has given the name of Tachymeter (rapid measurer). Its object is to give the area of plane surfaces bounded by any outline whatever, without the necessity of any arithmetical operation. There are several means more or less rapid for ascertaining the areas of plane surfaces, among which that of the planimeter of MM. Oppikofer and Ernst has the remarkable property, that nothing more is necessary than to draw a point over the outline of any figure whatever, and the superficial content of it is marked immediately upon a dialplate by an index. M. Caïro, who has also devoted himself to reduce the calculation of surfaces of land, &c. to a purely graphic operation, substitutes for the figure proposed a number of trapeziums, having their bases parallel, and their height constant. This latter quantity is taken as the unit, so that if the mean bases are successively measured, the nunber of linear units contained in the sum of all these bases expresses that of the superficial units contained in the figure proposed. For a very long period it has been customary to calculate approximatively the area of an irregular curve, by means of equidistant ordinates taken so near to each other that the portions of the curve intercepted by them may be considered, without any sensible error, to be short right lines. A much greater degree of precision is, however, attained by considering the given curve, on the contrary, as an assemblage of small parabolic lines, in which three points are known. Legendre, in his Exercices de calcul intégral, has, in certain respects, improved this method. It is also given in several other modern works. But in the operations of the most extensive surveying, even in the most important of them, the former process may be safely employed; and it is this which M. Caïro uses. Although, in general, the area of any irregular figure bounded by a curved line, may be easily obtained by means of the tachymeter, yet when the space to be measured is any right-lined polygon, it is desirable to select a mode of decomposition which will lead to the end desired in the most simple and convenient manner. Now, in these cases, the instrument of M. Caïro, even following the process which he has himself described, abridges but very little the ordinary method of finding the area of a triangle, rectangle, &c. the bases and heights being known. Finally, though the tachymeter does not give, under any circumstances, the area of a plane figure with the same celerity as the instrument of MM. Oppikofer and Ernst, it is, however, of a very simple construction, and it may be advantageously substituted for the graphical methods used in surveying.PUISSANT. Height of Waves at Sea, THE following observations on the height of waves in the open sea, were made during a voyage from Dieppe to Newfoundland, in the Spring of the present year. Though evidently, but approximations, we give them as an instance of the extensive and valuable effects which scientific circulars, of the nature of that* compiled by M. Arago in the Annuaire of this year, are calculated to produce. Pointing out the untrodden fields of nature, and describing the links still wanting to complete the chain of scientific investigation, they urge observation in the right direction; and suggesting, at the same time, the mode of operation, they render its exercise easy and inviting. 66 As we had not the dip-sector described by M. Arago, we could not use that means of measuring the height of waves; we, therefore, proceeded as follows. On the 26th of March, the day before a gale of wind, there being a heavy sea, M. Aigremont ascended the mast, and attempted to place his eye in a line which should touch the crests of two waves. This he found difficult to do. He then sought to refer the crest of a wave to the horizon, at the moment when the vessel was in the trough. The mean of several observations of this kind, gave 18 feet for the height of the waves. On the 29th, in the neighbourhood of La petite Solé, two vessels of different magnitude passed very near us during the day, running à contrebord, and crossing the waves. The sea was frightful; it may sometimes be worse, but rarely. These circumstances appeared favourable for the attainment of the measurement we desired. At the times when a vessel was in a trough of the waves, a position in which it was nearly upright, we remarked a point on the mast which was in the right line with two wave-crests in the interval between it and us, taking care that our eyes were in the same right line. The altitude of such a point on the mast above the sea, was evidently the height of the waves. We estimated the size of these vessels, (and sailors come very near the truth on such occasions,) and supposing their masts to be of the usual proportions, 崇 the mean of the observations made Publishing in the present and other numbers of this Magazine. on the larger vessel of the two, gave Comparative Intensity of the Solar Rays in different Latitudes. THE meteorological observations made navigators in the arctic regions, have during the later voyages of English excited a warm discussion among some physiciens, on the question, whether the solar rays thrown on the blackened bulb ofa thermometer, produce a greater poles. One party maintaining, that the effect at the equator than near the heating-power increases with the latitude; the other, considering this idea servations of Sir John Herschel, comto be rash and unsupported. Some obmunicated to the Académie des Sciences, on the 31st of October last, appears to restore, definitively, to the countries in the vicinity of the equator the privilege of which it has been attempted to deprive them. By means of a new instruschel found that, at the Cape, the direct ment, the actinometer, Sir John Herthermometical effect of the solar rays was 120° Fahr. In Europe, the maximum never exceeds 85°t.-ARAGO, The Weed-Sea.-Mar de Sargasso. "WILL you be kind enough to inform M. Arago, who recommended, in his Instructions for the Bonite, an examination, whether the numerous plants (Fucus natans) which are found in the open sea between the tropics, really + With deference to such high authority, we do not see how these insulated experiments are definitive of the question; nor how they subvert the facts given in Daniell's Meteorological Essays, and which induce I conclude, that the power of solar radia that author to observe, "From these facts, tion in the atmosphere increases from the equator to the poles."-ED. See page 478. vegetate in the middle of the Ocean, that I had the good fortune, in returning from Cayenne, some time before our second expedition to Iceland, to collect from a tuft of this very Fucus at 500 or 600 leagues (about 1700 to 2000 miles) from any shore, a bit of glass rounded by friction (roulé). This appears to me to be evidence, that the plant which contained it came from an inhabited coast, and that the same may be said of all the rest. The bit of glass is in the last collection of rocks, &c. which I sent to the Museum; in the catalogue will be found the latitude and longitude of the spot in which the fact occurred, and which I thought it proper to obtain."ROBERT. Letter from Iceland, July, 1836. Passive Patriotism. On the 4th of July last, the Académie des Sciences deposited in their secret archives, the model of a portable military telegraph, which may be used by night as well as by day, together with a dictionary of signals. The inventor of this machine, a M. Coulier, did not request that it should be submitted to any scientific or official examination by the Academy, but simply petitioned for the above cryptical deposition, in order, that if an occasion offered for its useful employment in the service of the French armies, its construction should not be previously known to the enemy! Electricity of Clouds. DURING the course of the summer of 1835, the far greater part of the clouds were electric, and nearly all which were so were positive. I scarcely found ten or twelve negative clouds among the whole mass which passed over my apparatus. This year it is very different. Up to the present time (August) the clouds have been generally neutral, and even among those that were supposed to be electric from their ashy colour, and their scalloped and changing edges, many did not disturb the repose of my apparatus. Those which were ascertained to be electric were nearly all negative; at least all have been go that I have had an opportunity of making any observation upon since March. This opposition in the electrical state of the clouds, in different years, will no doubt have the effect of rendering the problem to be solved far more complicated. But this is a very small matter, compared with the difficulties which the sudden or gradual changes produced by a mass of clouds present. These difficulties are such that I have little hope of solving even a few of them, compelled as I am to operate on far too confined a scale. My conducting wires are but about 90 feet above the surface of the ground, and do not penetrate it deeper than 40 feet. The apparatus is, therefore, constantly below the lower clouds, and receives the electrical influence from them only. It cannot, therefore, interrogate the superposed strata of clouds, to ascertain what belongs to each, and thus to obtain the necessary means for the analysis of the various phenomena which concur in the formation of tempests. Operations must be carried on upon a larger scale, in a country where lofty mountains would facilitate the fixing of the apparatus at different altitudes, so that it might indicate the electrical state of the clouds which interchange their electricities. I shall proceed to quote some observations which may be useful to those who are engaged in the same inquiries, or who may intend to be so. My apparatus consists of a copper wire, lapped with silk, and covered with several coats of thick varnish. The higher end finishes with a tuft of platinum wire, and the lower one is also of platinum, and is inserted in a well. In the middle is a multiplicator of 3000 turns of varnished wire, or an electroscope, according to circumstances. The electricity which forms the descending current of the wire being always of the same kind as that of the cloud, a simple indication of it is always sufficient to show that of the latter. On the 2nd, 3rd, and 8th of April last, the clouds being strongly negative, the deviation of the needle was main tained several times at 80° for four or five minutes. During the 8th, there were some great and sudden changes, which produced deviations of 90° in the opposite direction. As similar reverses are frequent at the moment of electrical discharges during storms, I do not doubt, although I did not hear them, that there were several claps of thunder. Each time that the negative deviation very suddenly increased, there followed a shower of rime or minute hail. I had |