« ПредыдущаяПродолжить »
commerce. signal officer, is in time of peace undergoing a thorough most important ends ever devised for the benefit of habits of exactness acquired by the Signal Corps in time is being educated to science, and also serving one of the he may be afterwards ihrown. The training, skill, and time that it is passing through a most thorough discipline, has a protission at all tunes lucrative to himself wherever training in the art of telegraphy and signalling, at the same the telegraph, and to becoine a skiliul operator. He thus
of peace will be of the greatest value to the army in time
At Fort Whipple, Virginia, every man is taught to use
The telegraph is capable of indefinite utilisation. ordered before a board, consisting of three army officers, General Von Moltke, it is well known, conducted the late for examination, when, if considered incompetent, he is operations of the German army on the battle-fields of returned to Fort Whipple for further instruction and France sitting in the rear with his map before him, and practice. his telegraphic operator at his side, keeping him in com- If, after a rigid examination, he is found capable, he is munication with all parts of the field. It has been fre- assigned to a station, and the necessary stationery and quently said by distinguished military men that the instruments furnished him (the latter consisting of the telegraph will be one of the most effective weapons in any barometer, thermometer, hygrometer, anemoscope, anewar that may now occur. How necessary for the Govern mometer, and rain-gauge), and instructions to make three ment to keep up the efficiency of such a corps as that of observations daily, viz., at the time corresponding with which we have spoken !
7'35 A M., 4.35 P.m., and 11.35 P.M. Washington time, so As the organisation under General Myer now exists, the that every observer at each station should be reading his President and Secretary of War have a responsible mili- instruments at the same moment, and in the following tary man at every important post in the country. If a order, viz., ist, barometer ; 2nd, thermometer ; 3rd, hywarlike expedition appears on any part of our coast, grometer ; 4th, anemoscope; 5th, anemometer; and 6th, causing a panic or stampede, there may be a thousand wild rumours of frightened message-senders. The Govern- In addition to the duties discharged by the officers of ment, however, is in the receipt every eight hours (and the Examining Board, Colonel Mallery, A.S.O., has the can be in the receipt every hour if it wishes) of a reliable general charge of the very large correspondence of the
office ; Captain Howgate has charge of the statistics and all observations of the service; and Lieutenant Capron has the difficult post of instructor of sergeants at Fort Whipple.
Where a single person has been required to do the work of a station, receiving full reports from all stations, the labour occupied twenty hours out of the twenty-four. But the rule now adopted is to provide each station with two men-one a sergeant in charge and the other a private soldier as assistant. The observer stationed on Mount Washington has been alone on the mountain most of the time, and always responsible for the work.
In addition to a number of officers who form the Board of Examination, General Myer is also ably assisted by Major L. B. Norton, the property and disbursing officer of the Signal Service.
Prof. Cleveland Abbé, long known as an officer of the Cincinnati Observatory, and as an eminent meteorologist, is employed chiefly in the work of making out the daily synopsis of the weather, and deducing therefrom the weather "probabilities,” which are given to the public by telegram through all newspapers desirous of furnishing them to their readers.
To the conspicuous ability of all of these officers is attributable the success of the enterprise.
The ordinary barometer in use by Signal Office observers is that of Mr. James Green (the well-known scientific instrument maker of New York)--an instrument adopted by the Smithsonian Institution, and also by the American navy, as the most perfect to be obtained.
This barometer has its cistern furnished with a small glass index, which shows when the mercury is at the right height in the cistern. This is adjustable by a screw which works through the bottom of the instrument against the flexible bottom of the cistern. The instrument is ready
for use when the mercury touches the little V-shaped message from its own agent, who reports on his responsi- index in the cistern. So simple and complete is this bility what he saw and knows to be true ; and this barometer that any one can use it, and it ought to be in observer will not leave his post until ordered to do so. the hands of all business gentlemen, and all who are inteAs a mere Government police, therefore, the Signal Corps rested in watching the mutations of the weather. would be worth to the nation far more than it can ever Latitude and longitude on the earth's surface mark very cost, even if its operations should be more widely extended, conspicuous differences in the mean barometrie pressure, as will speedily be done.
as will be seen by a study of the Isobarometric Chart for Each sergeant is sent to the Signal Service school for the United States, which we gave last week. instruction at Fort Whipple, Virginia, where he is imme- The barometer has a slight fluctuation also under diately supplied with Loomis's “ Text-book of Meteoro- several influences. It rises when the moon is on the logy," Buchan's “Hand-book of Meteorology,” Pope's meridian in some places. It has a diurnal oscillation, “ Practical Telegraphy," and the “Manual of Signals for amounting on the equator to more than one-tenth of an the United States Army," together with all the instruments inch, but in the latitude of New York to only o‘05 inch, necessary for practical instruction. The books he must the greatest height being about ten A.m., and the least thoroughly master. He is required to cite once daily about four P.M. The nocturnal variations are much less. didactically, and to practise a certain time with the instru- In the latitude of Philadelphia and New York the northments. He is required to remain under tuition until con- | east wind causes another variation of one-fourth of an sidered by the instructor competent to take charge of a inch, due to the meeting of two atmospheric waves giving station and perform the necessary duties, when he is a still higher wave, and hence a higher barometer. There
FIG. 6.-SECTION OF GREEN'S STANDARD BAROMETER
is also the variation due to the height of the observer's which may influence the barometer to the extent of two station above the sea. This is, of course, of the first inches. These causes, separately or conjointly with the importance. The other fluctuations are comparatively temperature, produce either steady or rapid barometric unimportant, and do not blind an observer to those oni- variations, according to their force. nous Auctuations which precede the storm, the tornado, and the hurricane. The oscillations which indicate a storm
PRESENT OPERATION OF THE SERVICE are very marked. The tornado which recently ravaged St. Louis was preceded by a gradual fall of the mercury
Although the Signal Service is yet in its infancy, and in the barometer, for thirty hours previous, of an entire
must be patiently nursed and cherished by the people for inch. At Boston, within thirty-seven years, the barometer
some years before it can expect to do and discharge its has ranged from 31'125 inches to 28:47 inches, the diffe- full mission, under General Myer's indefatigable care rence being 2.655 inches. At London it has ranged and skilful management it has already achieved much through more than 3'5 inches; but in the tropics not so
good, and more than compensated the public for the exmuch.
pense of its establishment. Since it was instituted last During the passage of a cyclone the mercury oscillates summer," the chief signal officer has," to quote the words rapidly. The most noticeable fall occurs from four to six of the New York World, “thoroughly organised and hours before the passage of the storm centre. This fall equipped a system which now embraces in its scientific is often over an inch, and sometimes two inches.
grasp every part of the land from Sandy Hook to the Great changes are usually shown by falls of barometer Golden Gate of California, and from Key West to the exceeding half an inch, and by differences of temperature
Dominion of Canada." exceeding fifteen degrees. If the fall equals one-tenth of
Three times every day synchronous observations are an inch an hour we may look out for a heavy storm. The taken and reports made from the stations-one at eight more sudden the change the greater the danger. But it A.M., one at four P.M., and the third at midnight. These is too often forgotten that the fall of the mercury is a fore observations are made by instruments, all of which are warning of what will occur in a day or two, rather than in perfectly adjusted to a standard at Washington. They a few hours.
are also all taken at the same moment exactly, these A variation of an inch is certain to be followed by a
observations and reports being also timed by the standard tornado or violent cyclone. In the tropics “the glass of Washington time. The reports from the stations are has been known to show a fall of more than an inch and transmitted in full by telegraph. By a combination of a half in one hour !
telegraphic circuits, the reports of observations made at The following guides in predicting weather changes are
different points synchronously are rapidly transmitted to selected from the " Barometer Manual” of the London the different cities at which they are to be published. Board of Trade, and are suggestive :
They are, however, all sent of course to the central office 1. If the mercury standing at thirty inches rise grad in Washington, These reports are limited to a fixed ually while the thermometer falls, and dampness becomes number of words, and the time of their transmission is less, N.W., N., or N.E. wind; less wind or less snow and also a fixed number of seconds. These reports are not rain may be expected.
telegraphed in figures, but in words fully spelled out. 11. If a fall take place with a rising thermometer and There are now about forty-five stations for which provision increasing dampness, wind and rain may be expected from has been made, and which are in running order. These S.E., S., or S.W.; a fall in winter with a low thermometer have been chosen or located at points from which reports foretells snow.
of observations will be most useful as indicating the Ill. An impending N, wind before which the baro- general barometric pressure, or the approach and force of meter often rises may be accompanied with rain, hail, or
storms, and from which storm warnings, as the atmospheric snow, and so forms an apparent exception to the above indications arise, may be forwarded with greatest despatch rules, for the barometer always rises with a north wind.
to imperilled ports. IV. The barometer being at 29.1 inches, a rise foretelis These stations are occupied by expert observers furless wind or a change of it northward, or less wet. But nished with the best attainable instruments, which are if at 29 inches a fast first rise precedes strong winds or every day becoming more perfect, and to which other squalls from N.W., N., or N.E., after which a gradual rise instruments are being added. with falling thermometer, a S. or S.W. wind will follow, The reports of observers are as yet limited to a simple especially if the rise of the thermometer has been sudden. statement of the readings of all their instruments, and of V. A rapid barometric rise indicates unsettled, and a any meteorological facts
existing at the station when their rapid fall stormy weather with rain or snow ; while'a steady tri-daily report is telegraphed to the central office in barometer, with dryness, indicates continued fine weather. Washington. VI. The grzatest barometric depressions indicate gales
Each observer at the station writes his report on manifrom S.E., S., or S.W.; the greatest elevations foretell fold paper.* One copy he preserves, another he gives to wind from N.W., N., or N.E., or calm weather.
the telegraph operator, who telegraphs the contents to VII. A sudden fall of the barometer, with a westerly Washington. The preserved copy is a voucher for the wind, is sometimes followed with a violent storm from the report actually sent by the observer ; and if the operator N.W., N., or N.E.
is careless and makes a mistake, he cannot lay the blame VIII. If the wind veer to the S. during a gale from the on the observer, who has a copy of his report, which must E. to S.E., the barometer will continue to fall until the be a fac-simile of the one he has handed to the operator. wind is near a marked change, when a lull may occur. The The preserved copy, is afterwards forwarded by the gale may afterward be renewed, perhaps suddenly and observer-sergeant to the office in Washington, where it is violently; and if the wind then veer to the N.W., N., or filed, and finally bound up in a volume for future N.E., the barometer will rise and the thermometer fall.
reference. IX. The maximum height of the barometer occurs When all the reports from the various stations have during a north-east wind, and the minimum during one been received they are tabulated and handed to the officer from the south-west ; hence these points may be consi- (Prof. Abbé) whose duty it is to write out the synopses dered the poles of the wind. The range between these and deduce the "probabilities," which in a few minutes two heights depends on the direction of the wind, which are to be telegraphed to the press all over the country. causes, on an average, a change of half an inch ; on the moisture of the air, which produces in extreme cases a dry stylus, and being pressed on the upper sheet, it makes a similar mark on
• Thin paper with black carbon paper between the sheets. The pen is a change of half an inch ; and on the strength of the wind, the sheets bencath i.
This is a work of thirty minutes. The bulletin of Whipple, Virginia), who will go forth hereafter as valued probabilities,” which at present is all that is undertaken, auxiliaries. It has been fully demonstrated by the signal is made out thrice daily, in the forenoon, afternoon, and officer that the army of the United States is the best after the midnight reports have been received, inspected, medium through which to conduct most efficiently and and studied out by the accomplished gentleman and able economically the operations of the Storm Signal Service. meteorologist who is at the head of this work.
Through the army organisation the vast system of teleThe “probabilities” of the weather for the ensuing graphy for meteorological purposes can be, and is now day, so soon as written out by the professor, are imme- being, most successfully handled. “Whatever else General diately telegraphed to all newspapers in the country which Myer has not done,” says the New York World," he has are willing to publish them for the benefit of their readers. demonstrated that there can be, and now is, a perfect net
Copies of the telegrams of "probabilities” are also work of telegraphic communication extending over the instantly sent to all boards of trade, chambers of commerce, whole country, working in perfect order, by the signalmerchants' exchanges, scientific societies, &c., and to men, and capable of furnishing almost instantaneous mesconspicuous places, especially sea-ports, all over the sages from every point to the central office at Washington. country.
Think of a single jump by wire from San Francisco 2,700 While the professor is preparing his bulletins from the miles eastward three times a day! When General Myer reports just furnished him by telegraph, the sergeants are undertook to put this system in working order, the telepreparing maps which shall show by arrows and numbers graph companies said it was impossible-no such thing exactly what was the meteorologic condition of the whole had ever been heard of in telegraphing. It is now a grand country when the last reports were sent in. These maps fait accompli, as much as the passing of the Suez Canal are printed in quantities, and give all the signal stations. by ships or the escaping from Paris by balloons.” * A dozen copies are laid on the table with sheets of carbon At present the signal officer aims only to give a synopsis paper between them, and arrow stamps strike in them of each day's weather, and a statement of what weather (by the manifold process) the direction of the wind at each may be expected or will probably occur. The “proba: station. The other observations as to temperature, bilities" so far have been most beautifully verified and barometric pressure, &c., &c., are also in the same way confirmed. put on them.
It is not thought wise to undertake more than can be These maps are displayed at various conspicuous points securely accomplished. The synopses and “probabiin Washington-e.g., at the War Department, Capitol, lities” are all that intelligent shippers and careful seamen Observatory, Smithsonian Institution, and office of the require. Shippers will not send their vessels to sea if the chief signal officer. They serve also as perfect records of weather synopsis indicates threatening or alarming the weather for the day and hour indicated on them, and weather. are bound up in a book for future use.
Travellers can consult the "probabilities” before leavEvery report and paper that reaches the Signal Office ing home; and any severe storm that menaces any city is carefully preserved on file, so that at the end of each or port is now specially telegraphed thither, and the
, year the office possesses a complete history of the meteo- announcement is made by bulletins posted in the most rology of every day in the year, or nearly 50,000 observa- public places. tions, besides the countless and continuous records from By the modest estimate of the signal officers, the folall of its self-registering instruments.
lowing is a table showing percentage of "probabilities” When important storms are moving, observers send that have been verified : extra telegrams, which are despatched, received, acted
50 per cent. upon, filed, &c., precisely as are the tri-daily reports. One
Verified in part
25 invaluable feature of the system as now organised by
25 General Myer is that the phenomena of any particular
It must, however, be borne in mind that the failures storm are not studied some days or weeks after the occur
have often been due to lack of information from points rence, but while the subject is fresh in mind. To the
where as yet no observer-sergeant is stationed. study of every such storm, and of all the “probabilities.”
FUTURE issued from the office, the chief signal officer gives his personal and unremitting attention. As the observations The Signal Service has, up to this time, acted upon the are made at so many stations, and forwarded every eight wise maxim of " making haste slowly," and undertaking hours, or oftener, by special telegram from all quarters of to do nothing which was not in its power to do safely the country, the movements and behaviour of every de- and securely without risk of failure. It has acted upon cided storm can be precisely noted ; and the terrible the confidence it has in the people that they will patiently meteor can be tracked and “raced down” in a very few await the development of solid science, meantime leaving hours or minutes. A beautiful instance of this occurred no stone unturned to hasten forward the observations on the 22nd of February last, just after the great storm which may lead to a more exact acquaintance with the which had fallen upon San Francisco. While it was still habits, movements, and tracks of our American storms. revolving around that city, its probable arrival at Corinne, Great progress has in a very short time been made in this Utah, was telegraphed there, and also at Cheyenne. knowledge, and every day new light is dawning upon the Thousands of miles from its roar, the officers at the Signal science of storms. Office in Washington indicated its track, velocity, and The instruments of the service have been bought on force. In twenty-four hours, as they had forewarned trial. They are undergoing the most varied experiments. Cheyenne and Omaha, it reached those cities. Chicago In a short time, it is hoped, they will be greatly
, was warned twenty hours or more before it came. Its and perfected, and then the chief signal officer's results arrival there was with great violence, unroofing houses will be more satisfactory to himself, and his labours will and causing much destruction. Its course was telegraphed be greatly facilitated. The celerity with which important to Cleveland and Buffalo, which, a day afterwards, it duly results have already been attained by this officer has survisited. The president of the Pacific Railroad has not prised and startled both himself and the friends of the more perfectly under his eye and control the train that great movement. left San Francisco to-day than General Myer had the As soon as possible, therefore, the Signal Office will storm just described.
have its signal posts along the lakes and on our Atlantic While the observers now in the field are perfecting sea-board, where cautionary signals will be displayed, themselves in their work, the chief signal officer is train- warning vessels of approaching gales and storms, and ing other sergeants at the camp of instruction (Fort
New York World, March 5, 1871.
also a signal for clear weather. These will be displayed months. At Fourneaux things were even worse, there by day and by night by a very simple and suitable con- being an ordinary population of only 400 inhabitants. trivance now being perfected by General Myer. In New The first problem to be solved, says Mr. Fras. Kossuth, York already arrangements have been made for displaying one of the Royal Commissioners of Italian Railways, in the signals to shipping in the harbour from a lofty struc- his able report on the Mont Cenis Tunnel, was threefold. ture on the roof of the Equitable Life Insurance Company's (1) To fix across the mountain several points which would office, the best station that could be chosen. The display all be contained in the vertical plane drawn through the of these storm signals proper will place the American axis of the tunnel. (2) To obtain the exact length between Signal Bureau at once in a position to render inestimable | the openings. (3) To know the precise difference of level service to shipping and all commercial interests.
between the two extremities of the tunnel, so as to obtain These signals will at first be neglected by ruder and the proper gradients. In order to execute this programme, more unskilful seamen and shippers ; but, as in the case a series of observations was established on all the faof the famous Fitzroy signals on the English coast, every vourable points, and an elaborate trigonometrical survey week will add new demonstrations of the value and urility of the district was commenced. By the end of ihe season of this system-one of the most splendid gifts bequeathed little could be done in the way of surveying; in the winter by modern science to the human race.
of the year 1858 all the surveys relating to the alignment The signalling of storms and desolating cyclones to the and to the length of the tunnel were completed, and all unsuspecting seaman will, it is believed, mark a new era was ready to compile the longitudinal setion along the in our lake and coast navigation, and be the means of axis of the tunnel The whole system consisted of twentyannually saving many lives and millions of dollars' worth eight triangles, and eighty-six was the number of mea. of our floating property.
sured angles. All of these were repeated never less than The comparison of these signals with the weather fol- ten times, the greater part twenty, and the most important lowing the signals will be then a matter of special atten- as many as sixty times. To give the reader an idea of tion. Every discrepancy can then be carefully noted and the extraordinary care and accuracy with which the surprobed, and every day the meteorologists in charge of the veying operations were carried out, it may be mentioned
probabilities” will find the means of rectifying any that Signor Mondino repeated his experiments for obtainerrors they may have fallen into, and daily increasing the ing the level of the tunnel, or rather of the signals over accuracy and perfecting the plan of their forecasts. the mountain in 1857 and 1858, and the difference in the
The storm signals will be displayed at any hour of the two surveys (over more than 13,000 yards), was only day or night when the instruinental indications give notice 3'93 inches. Even this was reduced afterwards by Signor of bad weather; and experience has already shown that | Termine to 1'57 inch. The preliminary measurements generally at least twenıy-four hours' fore warning can be gave a distance of 13,861'5 yards between the two tempogiven from the central office in Washington of all im- rary openings We say temporary openings, because, portant weather phenomena. With the telegraph to pre- although the tunnel is itself constructed in a perfectly monish, forecasts for two or three days in advance are straight line from Fourneaux to Bardonnecchia, passenhazardous and unnecessary. For almost all practical gers will not pass through the original straight tunnel, but purposes of life a day's notice of atmospheric disturbances will be conveyed through a branch one which joins the is quite sufficient, and more reliable than longer premo- main line a short distance from Fourneaux. The nature nitions. It will be a grand triumph for American science of the ground was such as to necessitate the definite when the electric telegraph is so utilised that it will and permanent tunnel being taken through the mounbring all citizens of the United States into electric com- tain in a curve ; but even the unprofessional reader munication with each other, and the most fearful storm, as
will see that straight line was indispensable, well as the sunshine and shower, shall be every day a
in order to
not only accuracy of direction, subject of forewarning or congratulation throughout the but also a through draught of air through the whole land, and even on the lakes and oceans that wash the length of the tunnel. A most important consideraAmerican coasts.
tion this latter, as one of the main objections brought against the scheme was the supposed difficulty there
would be in keeping the tunnel thoroughly well ventilated. OPENING OF THE MONT CENIS TUNNEL
It was also much easier to transmit the necessary motive
power along a straight line than on a curve. The tunnel, The present the favourite' designs of that ardent paHE project of constructing a tunnel under the Alps although its axis was straight, was not constructed on a
dead level. The gradients were : From the Bardontriot and eminent statesman, the late Count Cavour- has necchia (Italian) end, 4,408.50 feet above the level of the now been accomplished, thanks to the skill of the Italian sea, 1 in 2,000 (0002 per metre) for a distance of 20,997'33 engineers. The scientific requirements and methods feet. From the Fourneaux entrance (French side), 3 945 adopted are well stated in a recent article in the Daily feet above the sea, the rising gradient was I in 43 4782 News, to which we are indebted for the following inter- (023 per metre) for 20,587 feet. esting particulars : —
The absolute figures are as follows:
4,38125 donnecchia and Fourneaux, the former on the Italian, the Rise of gradient of 1 in 2,000 for 20,048 feet :
10024 latter on the French side of Moni Fiejus, the tunnel being nearly pierced under the above-named mountain, and not,
Summit level from Bardonnecchia 4,391'274 as common report would have it, beneath Mont Cenis. These two villages were of the smallest size and most
Elevation above sea-level at Fourneaux entrance 3,946.50 miserable character, and offered no accommodation what
Rise of gradient of 1 in 45,045 for 200,045'10 feet. 445.00 ever to the many hundred workmen employed on either
Summit level from Fourneaux 4,391.50 side the mountain. Bardonnecchia, on the Piedmontese side, is a village which, in 1857, when the works com- This shows a very slight difference from the calculations menced, contained about 1,00 souls. The houses of the summit level as reckoned at Bardonnecchia, and in it were really little better than huts, being gives a mean level for the highest point of 4,391 386 feet. mostly occupied by shepherds, who were absent with | The greatest height of the mass of the Alps over the their flocks on the mountains during the
tunnel is 5,307 feet.