Fig. 2.-THE METEOROGRAPH. est point, the registering pen G being at the bottom of the drum. Now, in order that we may be able to register the barometer on any part of the drum sheet, it is necessary that the striking hammer should be elevated and locked before the upward motion of the lever commences. As the hammers are raised by means of an arm carried by the hour shaft of the clock, at the point where the hammers begin to rise the snail for elevating the lever A is cut away, so that it remains at rest during a period of fifteen minutes, the time required for elevating the hammers H and H'. As soon as this is accomplished the lever begins to rise slowly, by means of the double snail on the hour shaft, the time required for traversing the drum being about fifteen minutes. When the position of the lever is such that the carriage in the rear of the clock touches the float in the shorter leg of the siphon, an electric current is established through the magnet, F, which un- |ures of the invention of Professor Hough is that locks the hammer H, causing the pen G to it prints its own records. And this is done by make a record on the drum sheet. After the a single screw, which rises or falls with the merlever has reached the top of the drum it re-cury in the barometer. This screw carries a mains at rest fifteen minutes, while the ham- pencil, which traces upon a revolving cylinder mers are being raised, when it is gradually de- or roll of paper a line showing the minutest pressed. So soon as the platinum wires-at- movements of the column of mercury for every tached to the carriage over the thermometers-minute in twenty-four hours. This same screw touch the surface of the mercury in the ther- also gives motion to a series of wheels which carry mometer tubes, electric currents are established types, by which, at the end of every hour, the height through the magnets F and J, simultaneously of the column of mercury is printed on a slip of or successively unlocking the hammers, and, as paper to the accuracy of THE THOUSANDTH PART the case may be, making records as before. OF AN INCH! A complete double motion of the lever re- One of the most beautiful and simple contrivquires one hour. During this time the baromances used is a Wild's self-registering barometer, eter and wet and dry bulb thermometers have of which we give a cut one-quarter the actual each been recorded once. The records of the size. It scarcely needs explanation except to barometer and thermometers differ in time about say that the tube, A, is suspended in a cistern half an hour. The wet and dry bulb thermom- of mercury, represented on the left of Fig. 1. eters are recorded within about one minute of As the atmospheric pressure changes, the level each other, depending on the difference between of the mercury changes in the cistern, and the them. tube A rises or falls as the atmospheric pressure One of the most marked and wonderful feat- increases or diminishes. The weight of this four hours. At the end of every day this part of the roll is detached and put by to be bound up in book form in the records of the office in which the instrument is kept. The roll of paper is on a reel, n, passing between two rollers, g and k, as seen in Fig. 3. By these perfectly simple devices, instead of obtaining only three daily recorded observations, the observer at every station gets a continuous and perpetual record for every second in the day. That is to say, instead of getting, as by the common barometer (observed three times a day), observations for three seconds in twenty-four hours, he gets them for as many seconds as there are in twenty-four hours, or 86,400. Thus it follows that the value of the self-registering barometer, as compared with the ordinary one, is as 86,400 to 3! The marvelous accuracy and exquisite nicety with which all the observations forwarded to General Myer by the observers are marked ought to assure the public that nothing is wanting to give reliability to the published results and the "probabilities" issued from his offices. A self-registering barometer, as well as other instruments of equal sensitiveness, will be used by all the observer-sergeants. It is scarcely possible for this invaluable instrument to suffer derangement or to get out of order. A third most beautiful and sensitive self-registering instrument is that of Mr. Peelor, of Johnstown, Pennsylvania, used with great success and satisfaction by the Signal Service. This needs no battery, no electricity, to work it. A simple clock-work is all that is required, and its operations are as exquisitely accurate and trustworthy as the best navy chronometer. A barograph and thermograph made by Mr. Beck, of London, similar to those used in the Kew Observatory, are on trial in the Signal Office, and good results are hoped from them. Their beautiful machinery might also be mentioned and described, but our space fails. Indeed, our limits have allowed mention to be made only of the most novel instruments em of one of these is presented on page 414, showing the synchronous readings, on a given day and at a given place, of the thermometers (wet and dry bulb), the hygrometer, and the barometer, all upon one sheet of paper. tube as it floats in the mercury, and also that of the arm, I, which supports it at G, is exactly balanced by the arm, II, to which is attached a sliding weight, III, adjustable by a small thumb-ployed by the signal offices. A specimen record screw. K is a steel crayon-holder fixed to the balance I II, and to which is fixed a crayon, c, whose point is seen in Fig. 3 to impinge upon a sheet of paper, l l. This sheet is moved by clock-work. When the atmospheric pressure is increased, the tube A is forced to rise a little We have already spoken of the beautiful out of the mercury in which it floats, and as it adaptation of Professor Hough's meteorograph rises at G the arm I is elevated. The crayon- to the work of printing its own registrations. holder, being fixed on the balance at the ful- The mechanics of meteorology have been adcrum, f, by two little screws, swings a little to vanced one step higher than this, and the registhe left, and the crayon which it carries with trations of the automaton are instantly and perit makes a mark on the paper beneath it, which fectly photographed. The sheet of paper, suitmark indicates the rise of the barometer, or the ably prepared for photographic impressions, is increase of atmospheric pressure. If the press- made to slide, by means of clock-work, before ure decreases, the pencil, of course, moves in the a gas flame. The mercury in the tubes proopposite direction, and shows the barometric tects a portion of the paper from the action of fall. The roll of paper on which the record is the light of the lamp, while above the mercury made by this automatic instrument is divided the rays of the lamp fall unobstructed upon the into rectangular parts, each one of which ex- paper, and, making their impression, reveal the hibits the atmospheric variations for twenty-exact height of the mercury in the tubes. The "photograph of a storm," page 415, shows the movements of the mercury in the two thermometers and barometer for twelve hours. This process, by which the weather is photographed, is employed by General Myer, and these necessarily exact records will prove most attractive pictorial representations of the great storms in the atmospheric ocean for the study of meteorologists all over the world. PRESENT OPERATIONS OF THE SERVICE. Although the Signal Service is yet in its infancy, and must be patiently nursed and cherished by the people for some years before it can expect to do and discharge its full mission. Under General Myer's indefatigable care and skillful management it has already achieved much good, and more than compensated the public for the expense of its establishment. Since it was instituted last summer "the chief signal officer has," to quote the words of the New York World, "thoroughly organized and equipped a system which now embraces in its scientific Bulb.) DRAPER'S PHOTOGRAPHIC REGISTER OF BAROMETER AND THERMOMETERS AT NEW YORK, APRIL 28, 1870. (The upper line of the Thermometers is the Dry Bulb, the lower line is the Wet grasp every part of the land from Sandy Hook to the Golden Gate of California, and from Key West to the Dominion of Canada." Three times every day synchronous observations are taken and reports made from the stations-one at 8 A.M., one at 4 P.M., and the third at midnight. These observations are made by instruments all of which are perfectly adjusted to a standard at Washington. They are also all taken at the same moment exactly, these observations and reports being also timed by the standard of Washington time. The reports from the stations are transmitted in full by telegraph. By a combination of telegraphic circuits, the reports of observations made at different points synchronously are rapidly transmitted to the different cities at which they are to be published. They are, however, all sent of course to the central office in Washington. These reports are limited to a fixed number of words, and the time of their transmission is also a fixed number of seconds. These reports are not telegraphed in figures, but in words fully spelled out. There are now about forty-five stations for which provision has been made, and which are in running order. These have been chosen or located at points from which reports of observations will be most useful as indicating the general barometric pressure, or the approach and force of storms, and from which storm warnings, as the atmospheric indications arise, may be forwarded with greatest dispatch to imperiled ports. These stations are occupied by expert observers furnished with the best attainable instruments, which are every day becoming more perfect, and to which other instruments are being added. The reports of observers are as yet limited to a simple statement of the readings of all their instruments, and of any meteorological facts existing at the station when their tri-daily report is telegraphed to the central office in Washington. Each observer at the station writes his report on manifold paper.* One copy he preserves, another he gives to the telegraph operator, who telegraphs the contents to Washington. The preserved copy is a voucher for the report actually sent by the observer; and if the operator is careless and makes a mistake, he can not lay the blame on the observer, who has a copy of sheets. The pen is a dry stylus, and being pressed on Thin paper with black carbon paper between the the upper sheet, it makes a similar mark on the sheets beneath it. his report, which must be a fac-simile of the one he has handed to the operator. The preserved copy is afterward forwarded by the observersergeant to the office in Washington, where it is filed, and finally bound up in a volume for future reference. When all the reports from the various stations have been received they are tabulated and handed to the officer (Professor Abbé) whose duty it is to write out the synopses and deduce the "probabilities," which in a few minutes are to be telegraphed to the press all over the country. This is a work of thirty minutes. The bulletin of" probabilities," which at present is all that is undertaken, is made out thrice daily, in the forenoon, afternoon, and after the midnight reports have been received, inspected, and studied out by the accomplished gentleman and able meteorologist who is at the head of this work. The "probabilites" of the weather for the ensuing day, so soon as written out by the Professor, are immediately telegraphed to all newspapers in the country which are willing to publish them for the benefit of their readers. Copies of the telegrams of "probabilities" are also instantly sent to all boards of trade, chambers of commerce, merchants' exchanges, scientific societies, etc., and to conspicuous places, especially sea-ports, all over the country. While the Professor is preparing his bulletins from the reports just furnished him by telegraph the sergeants are preparing maps which shall show by arrows and numbers exactly what was the meteorologic condition of the whole country when the last reports were sent in. These maps are printed in quantities, and give all the signal stations. A dozen copies are laid on the table with sheets of carbon paper between them, and arrow stamps strike in them (by the manifold process) the direction of the wind at each station. The other observations as to temperature, barometric pressure, etc., etc., are also in the same way put on them. These maps are displayed at various conspicuous points in Washington-e. g., at the War Department, Capitol, Observatory, Smithsonian Institution, and office of the chief signal officer. They serve also as perfect records of the weather for the day and hour indicated on them, and are bound up in a book for future use. Every report and paper that reaches the Signal Office is carefully preserved on file, so that at the end of each year the office possesses a complete history of the meteorology of every day in the year, or nearly 50,000 observations, besides the countless and continuous records from all of its self-registering instruments. When important storms are moving, observers send extra telegrams, which are dispatched, received, acted upon, filed, etc., precisely as are the tri-daily reports. One invaluable feature of the system as now organized by General Myer is that the phenomena of any particular storm are not studied some days or weeks after the occurrence, but while the subject is fresh PHOTOGRAPH OF A STORM.-(Print from Photographic Register from Noon, December 13, 1870, Inch per Hour.) |