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persons who have a taste for physical geography. In an analogous way, anything of isothermal countries (countries of equal annual thermal temperature) has, for the first time, become really fruitful. Since Dove has taught us the isotherms of the several months chiefly on the land-since two-thirds of the atmosphere rest upon the sea-Maury's work is so much the more welcome and valuable; because it includes at the same time the oceanic currents, the course of the winds, and the temperature."
It is comparatively easy to map out the course of rivers over the land, and follow them from the glacier of the mountains to the ocean estuary, through their channels. This is but the visible half of the ceaseless circle which the waters make over the land. A far more difficult task it is to track the viewless winds, and weigh the watery freights they carry from the ocean, and lay down so lowly and gradually in the fog, the dew, the shower, and the noiseless snow; or to pursue the oceanic currents that feed these thefts of the winds, and map out their path
Parietibus textum cæcis iter.
The solution of the grand problems of physical science connected with navigation do not rest there; they overflow to other branches of human labor and interest. Agriculture, and the health and happiness of mankind, are blended with the course of the winds and the distribution of heat and moisture. The farmer, as well as the mariner, looks up and watches the appearance of the heavens; and plentiful crops and prosperous voyages equally depend on the agencies which set in motion the winds, and uplift the clouds from the ocean. The beauty and impressiveness of these signs, in which Nature addresses Man, render them worthy of the poet. Happy he who can read them aright.
THE LANGUAGE OF NATURE.-"The wind and rain, the vapor and the cloud, the tide, the current, the saltness, and depth, and temperature, and color of the sea, the shade of the sky, the temperature of the air, the tint and shape of the clouds, the height of the tree on the shore, the size of the leaves, the brilliancy of the flowers-each and all may be regarded as the exponent of certain physical combinations, and therefore, as the expression in which Nature chooses to announce her own meaning; or, if we please, as the language in which she writes down the operation of her own laws. To understand that language, and to interpret aright those laws, is the object of the undertaking which those who co-operate with me have in hand. No fact gathered in such a field as this, therefore, can come amiss to those who tread the walks of inductive philosophy; for in the
hand-book of Nature, every such fact is a syllable; and it is by patiently collecting fact after fact, and by joining together syllable after syllable, that we may finally seek to read aright from the great volume, which the mariner at sea, and the philosopher on the mountain, see spread out before them.
Among the friends and collaborators of Lieut. Maury may be mentioned Dr. Buist, a distinguished savant of India, who announces in the Transactions of the Bombay Geographical Society, that the Assistant-Secretary, Mr. Macfarlane, "has made considerable progress in the construction of wind and current charts, founded on the information supplied by ships' logs, and on the principle of Lieut. Maury." What has been done for the Indian and the Northern Atlantic Ocean reveals the value of concert of observation among the navigators and meteorologists of the world. In a letter to Lieut. Maury, dated 17th November, 1851, Dr. Buist, after alluding to a vast mass of facts collected by observers in the Indian seas, observes:
"Three years since, I began to perceive that we had certain classes of storms that occurred periodically, not only all over India, but all over the region to which my information extended, and that these were synchronous, or nearly so. I then began a series of maps, illustrative of the matter."
A system of stations and the co-operation of navigators is naturally suggested by what has already been done. It must be seen that a true science of meteorology is impossible from local observations. We may watch the height of the barometer, and record the amount of moisture in the air, set rain gauges for ever, and yet be merely accumulating facts that in themselves have no significance. The relations of the river, the rain, and the ocean, are not local; they belong to universal geography, and are, literally,
"General, as the casing air,"
the atmosphere which forms the invisible link in the mighty orbit of the waters about the earth. Nature herself seems here to refuse to be evoked by the efforts of the individual mind, and demands for the revelation of her secrets to be everywhere watched.
Towards the end of the year 1851, the idea of a conference between the meteorologists of Russia and those of the United States was suggested by Kupffer, a laborious meteorologist of the former country; and about the same time a proposition was made by the British Government that that of the United States should co-operate in making these observations at certain foreign stations, and according to instructions prepared by General Burgoyne, Inspector-General of Fortifications. This was felt to
be an auspicious moment to secure concert of action among meteorologists on shore, and co-operation among navigators at sea everywhere; and Lieut. Maury then, in reply to the British proposition, suggested that sea and land should be included as the field, and that a general conference of meteorologists and navigators should be held to discuss the plans, draw up the forms, fix the standards, and select the instruments to be employed on this grand field of research.
A UNIVERSAL SYSTEM OF OBSERVATIONS.—The basis originally proposed by the British Government to that of the United States, is contained in the instructions drawn up by order of the Inspector-General of Fortifications, Sir John Burgoyne, the circular letter of Lord Palmerston to British consuls, and that of Lord Glenelg to Colonial Governors. Nineteen principal stations in the colonies of Great Britain were selected as the points of regular record. These were to be supplied with sets of instruments of similar construction. Twenty sets were to be sent to India, by the Board of Directors of the East India Company, and provision made of the same character for observations at Ascension, Rio de Janeiro, Callao and Valparaiso.
The circular addressed to the officers of the government of India, desires them
"Upon the occurrence of any hurricane, gale, or other storm of more violence than usual, to note accurately the time of its commencement, the direction from which the wind first blows, whether in gusts or regular, and whether accompanied with rain, thunder and lightning, or other phenomena. Also, to note, with as much accuracy as possible, the changes of direction in the wind, and the time of occurrence of each; and lastly, the duration of the gale, and in what quarter the wind is when it ceases. The variations of the thermometer and barometer at each period noticed will also be of importance, if the means are forthcoming of making such observations."
On the transmission of these instructions to the United States government for the purpose of securing its co-operation in the plan, Lieut. Maury brought forward as an amendment a system of universal observation on sea as well as on land, and securing the assistance of the commercial marines of the civilized nations of the earth in carrying out its details. We copy the following from the paper of Lieut. Maury on this subject:
"The importance of concert among meteorologists all over the world, and of co-operation between the observer on the shore and the navigator at sea, so that any meteorological phenomenon may be traced throughout its cycle both by sea and land, is too obvious for illustration, too palpable to be inade plainer by argument; and, therefore, the proposition for a general conference to arrange the details of such a comprehensive
system of observations, addresses itself to every friend of science and lover of the useful in all countries.
"The domain of this science of the atmosphere: its boundaries embrace the land and cover the sea. To comprehend the laws which govern the movements of a machine so vast as it is, requires that its operations should be observed in all its parts and watched from all points at the same time. Its motions are freer and less obstructed over the water, than they are by the land and across the mountains. Indeed, the ocean itself may, in one sense, be regarded as a grand expression of meteorological agencies; therefore the good-will and friendly co-operation of private ship-owners and masters, in all maritime countries, are considered of great importance to the cause in hand."
The proposition for a universal system of observation, as suggested by Lieutenant Maury, was soon after submitted to the Royal Society, and, so far as an extension of these to the sea is concerned, it received a warm approval. The report adopted by the society recommends that instructions similar to those given to American shipmasters, according to the scheme submitted by Lieutenant Maury to the Bureau of Ordnance and Hydrography in 1842, be given "to every ship that sails" from British ports, with a request to transmit the results of them to the Hydrographer's Office of the Admiralty. The labors of the two greatest naval and commercial nations of the world, it is hoped, may be thus united in promoting the interest of navi gation.
The additions that have been made to geographical science since American shipmasters have been engaged, under the guidance of Lieutenant Maury, in the business of watching and recording the course of the winds, the clouds, and the currents, have not been few or unimportant. The power of such discoveries in changing the course of trade is well illustrated by the influence of the Gulf Stream on the trade of Charleston. During the colonial times, the course of trade was to make that port the half-way house for vessels bound from England to the northern ports. If driven off the coast during the winter by gales and snow-storms, they returned to Charleston, and there remained until spring. When Dr. Franklin taught the mariner to know when he crossed the banks of this ocean river, by dipping a thermometer into the water, it was, to use the graphic words of the navigators, as if blue and red lines were drawn on the ocean. This discovery shortened the passage to the west from sixty to thirty days. It changed the course of trade. Vessels, instead of running to Charleston to avoid a snow-storm, now stood off for a few hours, thawed out the ship and her crew in the warmth of the Gulf, and were ready for another attempt to make their port.
The view of the general circulation in the atmosphere, as traced by the investigations of Lieutenant Maury, is of the highest interest. The trade winds of the tropical seas have long been known, and form two links in the circuit of the winds around the earth. The ocean scenery of the region of the trades is among the most beautiful to the thoughts and the senses that can be conceived. The machinery of nature aiding so palpably the objects of man, and uniting lands divided so widely by the ocean; the canopy of flying clouds; the fresh and exhilarating breeze blowing day and night in one direction; the charming temperature and the moderate swell of the waves, make it the elysium of the mariner. The gentle spirit of the earth seems to be there bodily present; and the picture of a fleet hanging in the clouds, always an impressive object, becomes exquisitely poetic in its associations, when
They on the trading flood,
These trade winds are the great evaporating winds of the ocean; and, as we learn from the investigations of Lieutenant Maury, the belt of the S. E. trades in the South Atlantic is not only more extensive than the N. E. trades in the South Atlantic, but the winds themselves are fresher in the south. The very natural conclusion is, that the increased water thus taken up goes to feed in part the rivers of the northern hemisphere. At the equator these surface winds meet, and form a belt of calms, a node of upward winds, the northeast trade wind becoming a northwest upper current, and the southeast trade a southwest wind in the upper regions of the atmosphere overlying the north torrid zone. At the tropics, two other nodes of calms and of downward currents are met, with the two descending nodes of the orbit of the winds. The prevailing surface winds should now blow in spirals from the southwest towards the north pole, and in similar spirals from the northwest towards the south pole. At the poles the upward current produces another region of calms, whence the wind begins from north and south other revolutions towards the equator. And this system of winds is the source of
THE RAINS. "To evaporate water enough annually from the ocean to cover the earth, on the average, five feet deep, with rain; to transport it from one zone to another, and to precipitate it in the right places, at suitable times, and in the proportions due, is the office of the grand atmospherical machine. This water is evaporated principally from the torrid zone. Supposing it all to come thence, we shall have, encircling the earth, a belt of ocean 3,000 miles in breadth, from which this atmosphere