Show WONDERFUL WEATHER BUREAU cleveland plain dealer he that is weather wise Is seldom otherwise pays ays the proverb and the saying Is without a shrewd amount of truth perhaps nowhere can we find a combination of imperfect observation ge and inconsistent ahr than in the saws which form the in trade of the ordinary would weather prophet how common it is find men full of the conviction that weather must change at the so called changes of the moon forgetful that it if wed no moon at all and that may seem strange we still should have weather subject to change they will say truly enough no doubt that they have known the weather to change in new or full as the case way may toe ie and they argue that it therefore must always do so but in tact fact they have only noted a few chance coincidences and have let the great number lumber of discordances discor dances pass pasa by unnoticed but observations of this kind seem scientific and respectable compared with those numerous weather proverbs which are based upon the mere jingle of a rhyme as it the ash is ia out before the oak you may expect a thorough soak 8 proverb which is deftly inserted in some districts by making oak rhyme to t 0 choke others again are based upon a mere childish fancy as tor for example when the y young moon lying on her back to supposed to bode a spell of dry weather because it looks like a cup gna so might be thought of as able to bold the water waiter during the present reign however different method of weather ft very study has come into action and the foundations of a true weather wisdom have been laid these have been based not on fancied analogies or old wives rhymes or a few fore chosen coincidences but upon observations carried on oa tor for long periods of time and over wide vwe areas of country and discussed in their entirety without selection and bias above all mathematical analysis it g been applied to the motion of the air and ideas ever gi gaining in precision ft exactness have been formulated atthe at of the gen general eral circulation of the atmosphere ere ac compared va red with its ita sister science astronomy onomy O 1 meteorology appears to be 0 faff in s n lomery a very undeveloped state there such a difference between the power the astronomer to foretell the precise position of sun moon aw and I 1 planets planeta e for years even for centuries beforehand and the failure of the meteorologist to predict the weather for a single gingle season ahead that the impression has imm been widely spread that there to is yet no true meteorological science at all it to As forgotten that astronomy to is offered up IHL in the movements of the heavenly bodies the very simplest and easiest problem ism of related motion yet for how many thousands of years did men watch atch the planets and speculate ate concerning them before the labors of ty eho kepler and newton culminated in the revelation of their meaning for countless count leos generations it was supposed that shot their movements regulated the iwo arres characters and private fortunes fin men just as quite recently it was fancied that the new moon on an a saturday or two full moona moon tj well within the same calendar calenda month brought bad weather V it to in still impossible impassible to foresee the change for long ions ahead but in I 1 awe countries especially in the united tt it me has been found possible to I 1 the weather of the coming twenty four hours with considerable exactness and anc often to forecast the coming coining of a great storm several dabu ahead this is the chief purpose of the two great observatories of the storm swept indian and chinese seas hong kong and mauritius and the value ol of the work which they have done in preventing the loss of ships and the consequent loss of lives and property has been beyond all estimate the royal observatory greenwich is a meteorological as well as an astronomical trono mical observatory but it does not itself issue any weather forecasts the greenwich observations of weather are sent to the meteorological office there to be combined with similar records from every part of the british isles to form the basis of the dally daily forecasts which the latter office publishes to each of these three offices therefore the royal observatory greenwich stands in the relation of a purveyor it supplies them with the original observations more or less in reduced and corrected form without which they could not carry on most important portions of their work let it be noted how closely the three several departments the nautical almanac office the time department and the meteorological office are related to practical navigation whatever question of pure science of knowledge that is apart from its useful application may arise out of the following up of these several inquiries yet the first thought the first principle of each Is to render navigation more sure the first of all meteorological instruments is the barometer which under its two chief forms forma of mercurial and aneroid is simply a means of measuring the pressure exerted by the atmosphere there are two important corrections to which its readings axe are subject the first is for the bight of the station above the level of the sea the second Is for the effect of temperature upon mercury in the barometer itself lengthening the column to overcome these the bight of the standard barometer at greenwich above sea level has been most carefully ascertained and the hights bights relative to it of the other barometers of the observatory particularly those in rooms occupied by fundamental telescopes have also been determined ter mined while the self recording barometer Is i mounted in a basement where it is almost completely protected from changes of temperature next in importance to the barometer as a meteorological instrument comes the thermometer the great difficulty in the observatory use of the thermometer la Is to secure a perfectly unexceptional exposure so that the thermon ter may be in free and perfect contact with the air and yet completely sheltered from any direct ray my of the sun this to is secured in the great thermometer shed ast art greenwich by a double series of louvre boards on the east south and west sides of the shed the north side being open the shed itself is anade a very roomy one in order to give access to a greater body of air A most important use of the thermometer In Is in the measurement of the amount of moisture in the air to obtain this a pair of thermometers are in mounted close together the bulb of one being covered by damp muslin and consequently the two thermometers will read the same but it if the air be comparatively ively dry the wet bulb and its temperature will sink to that at which the air would be fully saturated with the moisture it already contained tor for the higher the temperature the greatti its power of containing conta inin g moisture the difference of the reading of tha the two thermometers is therefore an index of humidity the greater the difference the theater the power powe of ab sture moisture pr or in other words th the dry neon feea of the air the great shed abed already alluded to is devoted to these companion thermometers very closely connected with atmospheric pressure as shown us by the barometer is the study of the direction of the winds if we take a map of the british isles and the neighboring countries and put down upon them the barometer readings from a great number of stations and then join together the different places which show the same barometric pressure we shall find that these lines of equal pressure technically called isobars isobats iso bars are apt to run much nearer together in some places than in others clearly where the isobars isobats are close together it means that in a very short abort difference of country we have a great difference of atmospheric pressure in this case we are likely to get a very st strong rong wind blowing from the region of high pressure to the region of low pressure la III order to restore the balance if further we had information from these various observing stations or of the direction in which the wind was blowing we should soon precelle prec elve other relationships lations lation hipo ships for instance if we found that the barometer read about the same in a line of country from east to west but that it was higher in the north ot of the islands than in the south we should then have a general set of winds to the east and a similar relation would hold good it if the barometer were highest in some other quarter that in ia the p ri pe e wind will come from a quarter at right angles to the region of highest barometer or as it is expressed in what is known as buys ballots law stand with your back to the wind and the barometer will be lower on the leac lefthand than on your right this law holds good for the northern hemisphere generally except near to the equator in the southern hemis hemisphere piere the left hand is the side of low barometer the instruments for wind observation are of two classes vanes to show its direction and anemometers to show its if speed and its pressure these may be regarded as two different modes to in which the strength ot of the wind manifests itself pressure anemometers aw usually of two forms one in which heavy plate is allowed to swing gwing by ito upper edge in a position fronting the wind the amount of its devI deviation aVon from the vertical being measured ana aar the other in which the plate is supported by springs the degree of compression of the springs being the quantity registered in that case of the speed anemometers mo meters the best known form Is them the Rob lson pon four hemispherical cups cup a are carried at the extremities ov of a couple of crossbars cross bars the two chief remaining instruments are those for measuring the amount of rainfall and of full bunsh sunshine ine the rate rain guage consists essentially of a dunnet to collect the rain and a graduated glass to measure it the sunshine recorder usually consists of a large slaw glass globe arranged to throw an image of the sun on a piece of specially prepared paper this image moves movee along the paper as the sun moves in the sky ch arring it as it moves and at the end of the day it is easy to see from the broken burnt trace at what hours hour the sun was shining clear and when it was hidden by a cloud an amusing difficulty was encountered in an attempt to set on foot another inquiry the orthe meteorological department at the time wished to have a measure of the rate at which evaporation took place and therefore exposed carefully measured quantities of water in the oven onen airi in a shallow vesse for a few days day the record seemed quite satisfactory then the evaporation showed a sudden increase and developed in the most erratic and inexplicable manner until lt it was found that some same sp arrowo had come to the conclusion that tm full of water was mv a 4 tor for their morning tub and had made use of it accordingly A large proportion of the meteorological instruments at greenwich and other first class observatories are arranged to be self recording it was early felt that it was necessary that the records of the barometer and the thermometer should be as nearly as possible continuous and at one time within the memory of the members of the staff still living it was the duty of the observer to read a certain set of instruments st at regular two hour intervals draing the whole of the day and nighta night a work probably the most monotonous ot onous trying and distasteful of any that the observatory had to show the two hour record was no doubt practically equivalent to a continuous one but it entailed a heavy amount of labor automatic registers were therefore introduced whenever they wery were available the earliest of these were mechanical and several still make their records in this manner on the roof of the octagon room we rind find besides the two turrets already referred to a small wooden cabin built on a platform several feet above the root roof level this cabin and the north western turret contain the wind regis bering instruments opening the turret door we find ourselves in a tiny room which Is nearly filled by a small table upon this table lies a graduated sheet of paper in a metal frame and as we look at it we see that a clock set up ilose close to the table is slowly drawing the paper across it three little pencils test rest lightly on the face of the paper at different points one of these and usi bally the most restless Is connected with a spindle which comes down into the turret from the roof and which is to in tact fact the s spindle indle 1 of the wind vane the gearing fa is so 0 o contrived that the motion on a pivot of the vane is turned into motion matlon on a straight line at right angles to the direction to which the paper to is drawn by the clock A second pencil Is connected with the wind sure anemometer the third pencil in dilates the amount of rain that has fallen since the last setting the pencil being moved by a float in the receiver of time rain guage an objection to all the mechanical methods of continuous registration is that thai however careful the gearing earing be tween the instrument itself itsel f and the pencil nell Is in contrived however lightly the pencil moves over the paper yet some friction enters in and affects the ord this Is of no great moment in wind registration when we are dealing with so eo powerful en an agent as the wind but it becomes a serious matter when the barometer Is considered since its variation require to be registered with the greatest minuteness when photography therefore was invented mete were very prompt to take advantage of this new ally A beam or light passing over the head of the column of mercury in a thermometer or barometer could easily be made to fan upon a drum revolving once in four hours and covered with a sheet of photographic paper in this case when the sensitive paper Is de ve loped we ae fad its upper half blackened the lower edge of the blackened part showing an irregular curve as an the iner mercury cury in the thermometer or bar od neter rose or fell and admitted less or r more light through the space above it here we nave have a perfect means of registration the passage of the light exercised no im friction or check on an the free motion of the mercury in the tube or OB taft taming of the cylinder col cohered Vered by bw toe tm sensitive lVe paper while it Is in easy to obtain a time scale on OB the register by br cutting off of toe the tight light for an aa instant MW y at each hew am in ift taft ordythe way the wt vot A dalr thermometer thermo tn ta tb abe great to dato I 1 their W sum to am office to Is not the only use ot of the greenwich meteorological observations two elements of meteorology the temperature pera ture and the pressure of the atmosphere mo sphere have a very direct bearing upon astronomical work and this in two ways an instrument Is sensible to heat and cold and undergoes changes of form size or scale which however absolutely minute become with the increased delicacy of modern work not merely appreciable but important so too with the density of the atmosphere the light from a distant star entering our atmosphere suffers refraction and being thus bent out of its path the star appears higher in the heavens than it really is the amount of the bending varies with the ane density of the layers of air through which the light has to pass the two great meteorological instruments the thermometer and the barometer are therefore astronomical instruments ab well |