and knowing the present and antecedent rain fall higher up the river-valley, the office is thus enabled to calculate and announce the time and degree of coming changes. Thus timely premonitions of the great flood-waves that pass down the Mississippi, and also its fluctuations, are issued from the office to the places which it reached on its southerly way.

The gauge used is very simple. It is a plank (A, Fig. 2) of pine or oak timber, two inches thick, ten inches wide, and long enough, when placed obliquely on the slope of the riverbank, to cover the extreme low-water and high-water marks. When firmly imbedded in

the earth, the mean level of the river or "benchmark" is marked on it as zero, and it is carefully graduated in feet and inches by means of an upright measuring-rod (B), a straight-edge and spirit-level crosswise, as shown by the dotted lines (C) in the cut, each foot and its subdivisions exactly corresponding to the vertical foot and subdivisions of which they are intended to be indices. A "danger-line" is marked on the gauge, showing how tar the water may rise, but no farther, without danger of a flood. The reports telegraphed to the press, stating how near each stream has risen to or fallen below the "danger-line," enable the public to predetermine dangerous inundations, and furnish steamboat-men and merchants the daily information requisite for intelligently directing the movements of their craft. During the flood - months the tele

graphic river-reports are especially valuable to all river-shipping, and to all interested in the traveling and transportation facilities which depend upon it, as well as giving timely warnings of ice-floods or sudden rises and falls. The levee systems of the Mississippi and other great rivers can thus be guarded, and the immense agricultural interests secured, as the flood-warning comes in time to summon the State force to strengthen the imperiled works. Daily bulletins of the river-reports are regularly displayed at Augusta (Ga.), Cairo, Chattanooga, Cincinnati, Davenport, Dubuque, and Keokuk (Iowa), La Crosse (Wis.), Leavenworth, Louisville, Memphis, Morgantown (W. Va.), Nashville, New Orleans, Omaha, Pittsburgh, Portland (Oregon), Red Bluff (Cal.), Shreveport, St. Louis, St. Paul, Umatilla (Oregon), Vicksburg, and Yankton (D. T.).

In connection with this service, surface and bottom water-temperatures at points upon the rivers, lakes, and seacoasts are observed and reported for the United States Commissioner of Fish and Fisheries, with a view to ascertain the proper waters in which to plant the various food-fishes and furnish statistics desired for the development of the national system of pisciculture.

There is also to be mentioned the oversight given by the office to the changes of temperature by which the canals are closed by freezing, or opened by thaws for transportation. During the months when the market-rates and freightschedules are affected by the probabilities of the canals closing, and when these waterways are thronged with hundreds of laden barges, the daily predictions indicate the thermometric conditions likely to ensue along their lines of transit. Such information may often protect the public from the imposition of excessive railway-rates in the shipment of the graincrops, especially in any autumn season of protracted mildness, and effect a large saving to the mercantile world.

The Cautionary Storm-Signals, which accompany the "Synopsis and Indications" issued to the press three times each day, constitute a very important part of the Signal Service work; and it was the possibility of preparing such storm-warnings for the benefit of navigation that originally gave the chief stimulus to the establishment of a Weather Bureau. The United States has a double front with over 7,000 miles of sea-beaten coast, exclusive of the shore-line of its great lakes, rav aged by terrific tempests; and this vast stretch of marginal territory needs to be environed with stations from which observations can be taken, and premonitory intelligence of cyclone and anticyclone signaled by day and by night to storm-menaced shipping. If no other duty devolved upon the Service, this alone would more than justify its whole cost, and warrant its extension. It is one of the most difficult and responsible tasks which can fall to the meteorologist, to put his science to its utmost

stretch of accurate prevision (and often it must be done with a very few minutes for deliberation) to decide at what points on the coast the storm-wind will strike with dangerous effect. It is practically fatal to the value of his warnings if they are found to be superfluous, since in that case they cease to command the attention of seamen. Nor, for like reason, must they be displayed too late; nor yet too early, lest they should interfere with the movements of vessels which might run out of the dangerons vicinity before the storm can reach them. Thus the perplexing questions which spring up at every display of the signals lend to this part of the Service duty the intensest interest. No such work had ever been undertaken in this country when the Signal Service was organized; and though maritime storm-signaling on a small scale had been tentatively prosecuted in England by Admiral Fitzroy, his labors were held by his own Government of questionable success, and at his death in 1866 the experiment had been abandoned by it as premature, if not utterly hopeless.

On the organization of the United States Weather Service in 1870, the Chief Signal Of ficer began with great caution to prepare for this difficult and delicate part of his arduous task; and on the 24th of October, 1871, the display of signals on the seacoasts and lakes commenced. The order regulating this dis

play contemplated that the warning should be sent only to stations at which a storm-wind having a velocity of twenty-five miles an hour would occur. As the anemometer at every station registers the wind's velocity for every hour, it is easy to ascertain whether any signal has been justified. Every such display is carefully followed up by the office, and the result "justified" or "not justified "-is recorded, as reported by the observers hoisting the signals by telegraphic order from the Chief Signal Officer.

The cautionary signals are of two kinds: 1. Those premonishing dangerous winds to blow from any direction; 2. Those premonishing off-shore winds, likely to drive vessels out to sea. Both kinds are needed by mariners as the storm - centers approach or depart from a maritine station. The first, distinctively termed the "Cautionary Signal," consists of a red flag with a black square in the center, for warning in the daytime, and a red light by night. The second, or "Cautionary Off-Shore Signal," consists of a white flag with black. square in the center shown above a red flag with square black center by day, or a white light shown above a red light by night, indicating that, while the storm has not yet passed the station, and dangerous winds may yet be felt there, they will probably be from a northerly or westerly direction. The display of

and that of the number of "cautionary" sig nals displayed, 79.8 per cent. have been afterward reported as justified by dangerous winds; while of the number of "cautionary off-shore signals displayed, 93.9 per cent. have been afterward reported as justified. According to the rules of the office, a signal is set down as not justified unless it is shown after the dis

play that storm-winds exceeding twenty-five iniles an hour in velocity have occurred at the display-station or within a radius of one hundred miles.

The total number of seaports and points on the lakes and seacoasts where the storm-signals are hoisted now is one hundred and eleven. The points whence storm-signals are displayed, however, are only those of the maritime margins of the field of research. The network of the Signal Service stations now extends over the continent from the Atlantic to the Pacific coasts, and the intervening territory from the Gulf to the Canadian frontier, and is in receipt of daily telegraphic intelligence of the weather from the Canadian Dominion and its outlying posts. The office work is still hampered for want of more stations in the interior and Northwest; but it is thought provision will ere long be made for supplying them, as a new transcontinental telegraph-line is carried from Minnesota to the shores of the Northern Pacific.

Sunset Stations.-In this connection it may be as well to add that, besides the regular stations reporting by wire thrice daily to the office of the Chief Signal Officer, "sunset stations," as they have been called, have also been established. By careful study of the condition of the sky at sunset, especially on the interior plateau, it was believed an advance could be made toward a simple method of predicting the next day's weather, within the grasp of any unscientific but intelligent observer. The observers at the sunset stations note whether the western sky at the precise time of sunset is "fair," "foul," or "doubtful," and from these observations with others (instrumental) they make predictions for the ensuing day. Some of these observations are roughly spectroscopic, the sunset report being based in part on such different appearances of the sun and the effects produced by his rays as are caused by their passage through differently conditioned atmospheric media. The sergeants of the Signal Corps practiced in this kind of forecasting have acquired considerable skill and accuracy in predetermining the local weather-changes; their forecasts, as computed in the Chief Signal Office, having reached a percentage of 82.6 of cor rectness for trans-Mississippi districts, where the meteorological conditions are most constant, and 81.6 for the region east of the Mississippi Valley. "There can be no reason," says the Chief Signal Officer, "why any intelligent farmer, supplied with the necessary simple instruments, habituated to similar observations, and furnished with data, should fail to attain an equal accuracy."

Private Forecasts. To facilitate such private forecasting, especially by the agriculturists of the great West and the interior plateau, the Chief Signal Officer has caused to be prepared the "Weather - Case," or "Farmer's Weather-Indicator," before mentioned. This instrument is very simple, and when thoroughly tested, and by aid of the accompanying rules

for using it, it is hoped agriculturists and persons of ordinary education will find it possible to determine for themselves in advance the character of the weather from local indications. At isolated places, where the official reports can not be had, the diligent practice of such forecasting would probably in a short time afford good results. It is to call into play the intelligence of the popular mind and train it in the highly utilitarian work of private prognostications, as well as to explain its own forecasts, that the Signal Office issues a "Synopsis" of the weather-data with every bulletin of "Indications." That the farmer and seaman may know the changes going on each day, and acquire the habit of tracing the sequences of meteorological phenomena, the Synopsis" is invaluable. Most of the newspapers print only the "Indications," and omit the "Synopsis "-a practice to be greatly regretted. The late Professor Smee, F. R. S., one of the most gifted and practical of modern scientists, was much interested in the stormsignals hoisted on the English coast by Admiral Fitzroy. After much personal intercourse with the English fishermen, and close inquiry into the use made of Fitzroy's "warnings" among the humble coasters, he recommended that the reasons for hoisting the signal" should be communicated to the public, that those interested might study the official warning in its local applications. The Signal Service has always encouraged the private study and intelligent local application of its press reports, and expects those who use them to consult their own barometers and other instruments, and to examine the local signs of the weather, as clouds, etc., with the view of giv ing greater efficacy to its necessarily brief telegrams. Its plan is, not to deliver oracular and dogmatic statements to the people, but to guide them rather to meteorological knowledge as it is daily needed.

In the execution of the last-named plan, the "Daily Graphic" of New York publishes every twenty-four hours a reproduction of the Signal Service weather-map, showing the cyclonic, anti-cyclonic, thermometric, wind, rainfall, and other conditions prevailing over the country at the time of going to press. These charts, according to a plan devised by Lieutenant H. H. C. Dunwoody, Acting Signal Officer and Assis tant, are transmitted from the Washington office by telegraph. By this ingenious device, it is found not difficult to transmit to any city reached by telegraph-and by the common telegraphic instrument-such data prepared in the Chief Signal Office as will enable any newspaper to reproduce on its pages the official weather-map for the current period. Thus, the Signal Service weather-map for 1 A. M. of any day, precisely as charted then in the Washington office, can be telegraphed to Boston, Chicago, St. Louis, Indianapolis, or any other city, and published, in any size the editors may prefer, in the papers printed that morning!