62 j. 



NATURE 



{Oct. lo, 1878 



"keepers" are, when set, farther apart than they \rere 

 at the previous setting, or whether they are, when set, 

 nearer toe;ether than at^ the previous setting. 



If they are farther apart the thermometers are said to 

 be "separating." If they are nearer together the ther- 

 mometers are said to be "approaching." Other things 

 being equal, the thermometers show, when they are 

 " separating," that the air is becoming more dry: — one 

 sign of approaching fair weather. The thermometers 

 show, when they are " approaching," , that the air is 

 becoming more moist or damp — one sign of approaching 

 rain. 



The reservoir at the bottom of the weather case ought 

 to be kept half filled always with pure water. The wick- 

 ing must be kept clean and changed occasionally— say, 

 once in each month. 



Uses of the Weather Case 



The weather case is not intended to be used inde- 

 pendently of the official weather reports. It is to be used, 

 always in connection with them. The weather case' is 

 for the purpose of supplementing the official reports by 

 showing the local instrumental indications, and giving 

 other information. It is intended especially for use at 

 Farmers' Post Offices and places reached with difficulty 

 by the printed reports. It will supplement often whatever 

 knowledge there be of local signs, with the indications of. 

 the instruments. Its careful use taken either with the 

 furnished reports or even without them (if they chance to 

 fail), will often enable the characterof the coming weather 

 on the coming day to be so judged as to determine what 

 kind of work or undertaking it is wise to plan for or to 

 omit. The case gives the local instrumental indications, 

 and will frequently aid in making fair forecasts for the 

 next day. 



It is well to limit the forecasting to the attempt to tell 

 only whether it will or will not raiti on the next day. 

 Days on which it does not rain at all, are rated "fair," 

 though the sky may be covered with clouds. Days on 

 which there is rain enough to injure crops in the harvest- 

 ing, are rated " foul." 



It must never be forgotten that the weather case is 

 only to aid, sometimes, in making up one's mind as to 

 what the weather of the next day will be. While it will 

 often be very useful, there will be many instances in 

 which everything will be left in doubt. 



Location 

 The weather case should be hung or stand in a fair 

 light, where it will be always shaded, preferably on the 

 northern side or part of the house, where it will not be 

 exposed to artificial heat, and where there will be a free 

 circulation of the air. It will be easier to find good loca- 

 tions in summer than in winter. As the readings of the 

 instruments are examined for their general indications 

 only, the great care as to the location will not be so 

 needed for general use as if the readings were for exact 

 record. For particular uses, the case maybe particularly 

 sheltered. 



To Use the Weather Case at Sunset 

 (i) Read the description : See that the mean barometer 

 index is set to the mean barometer reading for the place 

 and for the month. 



(2) Set the rain wind segment (or arc) and the dry wind 

 segment (or arc) at the proper places on the wind-disc 

 circle for the place and month. 



At sunset turn the "long barometer pointer" until it 

 covers the "short barometer pointer." Note whether on 

 the " main barometer scale " the long pointer is then at a 

 reading above or below (greater or less than) the mean 

 barometer reading for the place and for the month. 

 Move the "sunset barometer index" until it points to 

 the same reading on the " main barometer scale ' ' with 

 the " long barometer pointer." 



Note the direction of the wind and set the wind-disc 

 pointer. 



Set the sunset-disc. 



Set the dry- and wet-bulb thermometers. 



Endeavour to apply the "indications" printed on the 

 face of the case, to determine what is to be the character 

 of the next day. Read these "indications" carefully, 

 and see how many of the instruments or discs agree in 

 showing one or another kind of weather as to be 

 expected. 



Study the character of the clouds. The scud cloud is 

 one of the prominent signs of coming rain. Learn to 

 apply the local signs of weather changes, the more the 

 better. 



Examine the case frequently during the day. 



It can always be found whether the "pointer" is 

 moving toward the right or left — that is, whether the 

 barometer is rising or falling — by turning the long pointer, 

 so as to cover exactly the black barometer pointer ; if 

 then, on next examination, the black pointer is found to 

 have moved toward the right, the barometer is rising. If 

 the black pointer has moved toward the left, the baro- 

 meter is falling. 



At sunset of the next day set the case again ; note 

 whether the barometer has risen since the " Sunset Baro- 

 meter Index" was set at the last sunset, whether the 

 wind is in the rain or the dry direction, and for how 

 many hours it has been in either, approximately. Study 

 and record the character of the sunset and what it fore- 

 tells. Set the wet- and dry-bulb thermometer, and note 

 from the "keepers " whether the thermometers are ap- 

 proaching or separating. 



Endeavour to make a forecast whether it will or not 

 rain for the ensuing day, as well as a more general 

 forecast. 



For instance, if with a "fair weather sunset" there is 

 a " high and rising barometer," "winds in dry direction," 

 and "thermometers separating," the chances for a fair 

 day for the next ensuing are increased ; four indications 

 of pleasant weather coincide. If, with a "foul weather 

 sunset," the barometer is falling" (the pointer moving 

 toward the left), the winds are in the rain-wind direction, 

 and "thermometers approaching," four indications^ of 

 rainy or unpleasant weather coincide. So three indica- 

 tions may coincide, as, with " thermometers approaching " 

 there may be "fair weather sunset" — barometer pointer 

 moving toward the right or high barometer — wind steady 

 in the dry direction. The indications may be divided. 

 In such cases weight must be given the different indica- 

 tions as experience may show their correctness. The 

 purpose of the case is to be one aid only in making up a 

 forecast. 



The greater the number of the "indications," as stated 

 on the face of the case, which are found when the instru- 

 ment is set, to coincide in indicating dry or clear weather, 

 or rainy or stormy weather, the more likely the success of 

 the forecast. 



Continue this practice at sunset from day to day. Skill 

 will be found to increase with the knowledge and the use 

 of the instrument and the habit of close observation of 

 local signs which such use makes necessary. 



In instances where the printed synopses and indications 

 are had regularly, or where official weather charts, bul- 

 letins, &c., can be consulted, the weather case must be 

 used with careful study of those papers. Locate the areas 

 of high and low barometer on the map, and in reference 

 to any location, as nearly as is practicable from the de- 

 scriptions or data. Areas of cloudiness, rain-areas, areas 

 of unusual temperature, &c., may be similarly located. 

 When any such areas are found to the westward of and 

 at all near any place, it is rare that the effects of them 

 fail to be shown at such place by weather conditions 

 similar to those within the areas noticed, and in a short 

 time, as of hours or days. As the movements of the 



