The observations of such meteorological phenomena as affect the fisheries continue to be published by the German government, under the supervision of the Commission to Investigate the German seas. This prompt monthly publication must greatly facilitate and stimulate the study and utilization of these data, and naturally suggests the advantages that must result from a regular monthly publication of all meteorological data specially pertaining to the United States fisheries, forestry, injurious insects, etc., etc.

The United States Fish Commissioner has collected an immense amount of data relative to water-temperatures, winds, currents, etc., in the United States rivers, lakes, and seas, which will be properly collated.

In a memoir on Red Snow, in the "Memoirs of the Academy of Toulouse,” vol. vii., Dr. Armieux advances the hypothesis that the Uredo nivalis of Bauer, or the Protococcus nivalis of Agardh, the Protococcus pluvialis of Cohn, and possibly the Lepraria kermesina of Wrangel are the same; and that to these spores, in different stages of development, are due the green, red, etc., snows-that, in fact, these cryptogams can also live on rocks, in peculiar circumstances, as at Rioulet.

Refraction of Light and Sound.

Dr. Fabitius, of Kief, shows that atmospheric refractions may be computed for great zenith distances on the assumption that the coefficient of refraction is constant quite as well as for small distances. To this end he simply adopts for distances greater than 75° a value of the reciprocal coefficient of refraction increasing in direct proportion with the zenith distance. He hence concludes that the constitution of the highest portion of the atmosphere has but little influence on the horizontal refraction, and that it is sufficient to assume for the upper portion the same law for the variation of temperature and density as obtains near the earth's surface. On this assumption he develops the formula for atmospheric refraction, which he is able to express in a series whose successive terms diminish very rapidly, and which are extremely convenient for the computation of special tables for any locality. The atmospheric refraction has been studied by Professor Kowalski, of the University of Kazan, Russia. With most other investigators, he pays special attention to the law of

diminution of the temperature of the air.

The law of this

diminution is, according to him, fixed by the mechanical theory of heat, and Lubbock, in 1856, was the first to find the solution to this question by starting with the principles of this theory. The present essay dates from 1867, or earlier. By the aid of the mechanical theory of heat, as developed by Thomson and Mendelieff, but with still further generalizations as deduced by. himself, Kowalski finds-first, during winter the diminution of temperature with altitude is, on the average, very small, and it augments in proportion as the temperature observed near the surface of the earth becomes higher; second, during the heat of summer the diminution of the density of the layers of air near the surface of the earth can become very feeble, so that the least force suffices to disturb the stability of the equilibrium of the layers, which case can rarely happen during winter; third, the variation of temperature in a higher stratum of atmosphere always manifests itself by the relatively greater variations taking place between the lower layers.

Kowalski's volume is, therefore, of interest to the meteorological observer principally because of its bearing on the question of the temperature of the air.

The important Experiments on Fog-signals, by Tyndall and others, under the auspices of the Elder Brethren of the Trinity House, have an important bearing upon meteorological matters, as they apparently give us a new method of exploring the atmosphere; in fact, as the spectroscope tells us of the total amount of moisture in a great length of the atmosphere, so do Tyndall's aerial echoes tell us of irregularities in density throughout a circle of many miles in diameter. Practically, however, the most important result of the Trinity House experiments has been to definitely establish the fact that two to four ounces of gun-cotton exploded 1000 feet above the sea by a rocket give forth such a volume of sound, and the sound-waves are so little affected by echoes or acoustic opacity, as to immensely surpass all other methods of fog-signaling hitherto tried. Such discharges were heard very loud at six miles, distinct, as distant thunder, at fifteen miles, and with a rumbling detonation at twenty-five miles. "A signal of great power, handiness, and economy is thus placed at the service of our mariners."

In the "Smithsonian Report" for 1877 is given a summary of the results of the investigations of Professor Henry in reference to fog-signals and the audibility of sound, and as this summary includes his very latest results, it will have permanent interest. He finds the most efficient cause of the loss of audibility is the direct effect produced by the wind. Sound is heard farther when moving with the wind than when moving against it. This is due to a change in its direction: it is refracted or thrown down towards the earth when moving with the wind, but passes over the head of the observer when moving against the wind. Sometimes a strong upper wind opposite to the surface wind produces an apparent reversal of the preceding law, as shown by his experiments in 1874. Although sound issuing from a trumpet or parabolic reflector is at first concentrated, yet it tends to spread so rapidly that at the distance of three or four miles it is heard nearly equally well on all sides. Neither fog, snow, hail, nor rain materially interferes with the transmission of sounds. Sound-shadows of great extent can be produced by buildings or other obstacles. The alternate audibility and inaudibility of a sound, as we approach to or recede from its origin, is attributed to the upward refraction of the soundwave and its successive reflections at the upper and lower surfaces, or the right-hand and left-hand bounding surfaces of shallow or narrow currents of air. The phenomenon of an aerial echo which comes back to the observer from a portion of the horizon directly in front of the trumpet is attributed provisionally to the fact that in the natural spread of the waves of sound, some of the rays must take such a curved course as to strike the surface of the water in a perpendicular direction, and thus be reflected back towards the origin of the sound.

Pneumatics and Aeronautics.

The ventilation of buildings and railway tunnels, etc., and the driving of the carriages in pneumatic tubes, railways, etc., introduce the application of principles and data that also have an application in meteorological problems; while, on the other hand, meteorological data relating to wind, temperature, and pressure enter into the computations of the engineers. Among these problems whose discussion we have noted during the past few years, we mention, the Ventilation

and Working of Railway Tunnels, by Morrison and others, in Proceedings of the Institute of Civil Engineers, art. xliv.; also, in the same volume, the Pneumatic Transmission of Telegrams, art. xliii., by Culley, Sabine, etc.-a very thorough and important discussion.

The enthusiastic aeronaut De Fonvielle writes to Captain Howgate to say that the study of clouds and currents by means of small balloons will be now systematically pursued at the Paris Observatory. This is, he states, in consequence of the fact that Captain Howgate (at Mr. Abbe's suggestion) furnished the meteorologist of his preliminary expedition with a quantity of these balloons for use in the arctic regions. The resistance that the air experiences from friction and obstacles on the earth's surface is in many ways shown to be a very important factor in meteorology; and as it is very difficult to make even an approximate allowance for this friction, it will conduce greatly to the reconciliation of theory with observation if some of the national meteorological systems will introduce the daily use of these balloons to determine the direction and velocity of the air-currents within 1000 feet of the earth's surface.

Professor S. A. King, formerly of Boston, and now of Philadelphia, continues to make aeronautic ascensions as much. as possible in the interest of the science of meteorology, although also strictly a business and professional matter. Could the results of his balloon voyages since 1851 be collected together, it would be seen that he ranks among the foremost aeronauts in his intelligent appreciation of the physical and meteorological problems that concern his profession. Such a work has, we understand, been in progress for some years, and doubtless now only awaits an enterprising publisher.

Professor Mendelieff is understood to be devoting his time to an extensive historical and scientific work on aeronautics.

spare

An important volume on aeronautics has been published by Tissandier, entitled "Histoire de mes Ascensions," being a record of twenty-four aerial voyages. The work gives special attention to the scientific exploration and study of the atmosphere, and is, of course, particularly valuable as containing Tissandier's own experiences.

The great event of the year in the application of aeronautics to meteorology has been the success of Giffard's giant captive balloon. This balloon has proved, as far as is known, perfectly manageable, and has made from two to twenty ascensions on every pleasant day, carrying up each time about forty persons (among them always a meteorological observer). The revenue derived from it has more than paid the original cost of the apparatus. A complete description of the balloon has been published by Tissandier, extracts from which have been published in numerous periodicals. The diameter of the inflated gas-bag is 36 meters; it was inflated with pure hydrogen made by the action of sulphuric acid on iron. The balloon is confined by a cable 660 meters long. The material of which the gas-bag is made has shown itself capable of retaining the hydrogen with scarcely any loss during four months. So complete has been Giffard's success that the Abbé F. Moigno, editor of Les Mondes, asserts that, had he been properly encouraged ten years ago by the French government, the investment of Paris could never have been completed, and the payment of five milliards need never have been forced upon France.

The receipts during the first 60 days exceeded $100,000, which was about the original cost of the balloon. In the beautiful weather of the commencement of October, the balloon accomplished between 8 A.M. and 6 P.M. 24 consecutive ascensions, so that in a single day 900 persons ascended and descended. The captive balloon is a veritable aerial sounding-line, and continually reveals the existence of superimposed currents which escape the observer on the ground. One is frequently plunged, at an altitude of 100 or 200 meters, into rapid currents, while the air is calm below; sometimes, on the contrary, the balloon is becalmed while strong winds prevail at the earth.

The Giffard balloon has been lately sold to a London company, and will be removed thither; while a new and larger one will be built to replace it in Paris.

Aeronautic ascensions were made from Paris, June 30 and July 2, in small balloons of only 450 cubic meters, or less than 14,000 cubic feet, but filled with hydrogen gas. According to Nature, it was on these occasions noticed that cumuli have a height sometimes twice as great as their hori