METEOROLOGY. 



21 



with meteorological instruments, to say nothing 

 of the interest that every tiller of the soil takes 

 in comparing one season with another, which 

 can only be done with any degree of accuracy 

 by the aid of a neatly-kept weather record. 



The meteorological instruments necessary for a 

 well-ordered garden need be but few in number 

 They are as follows: a barome- 

 ter, a maximum and a minimum 

 thermometer, a thermometer 

 sunk in the ground to give the 

 temperature of the soil, and a 

 rain-gauge. All the readings 

 should be taken, and the instru- 

 ments set, at a certain fixed 

 hour, the most suitable being 

 9 A.M. The observations should 

 be entered in a pocket note-book 

 each day in the same order, and 

 afterwards copied into a proper 

 meteorological register, 1 or any 

 other suitable book having lines 

 ruled for the purpose^ When 

 once the observer is able to take 

 the observations with ease, he 

 will find that they will occupy 

 less than ten minutes of his time 

 each morning. 



The Barometer. — There are 

 many forms of this instrument, 

 but the best for the purpose is 

 that known as the pediment 

 barometer (fig. 1). Asulficiently 

 good one may be obtained for 

 about 25.5. Like all other weather 

 instruments, great care is neces- 

 sary in selecting a suitable posi- 

 tion for it. It may be suspended 

 in any room not exposed to 

 sudden changes of temperature. 

 It must not be near a fire or 

 stove, or where the sun can shine 

 directly upon it. On the other 

 hand, it should be in a good 

 light, and at a convenient height from the floor 

 for reading its indications easily. 



The scale will be found to be divided into 

 inches and tenths of an inch. In order to take 

 a reading, turn the button beneath the scale 

 until the index-pointer attached to the bottom 

 of the vernier is just level with the top of the 

 mercury in the tube. By the vernier is meant 

 a narrow vertical plate with divisions upon it, 

 apparently similar to those on the scale of the 



1 Symons's blank Meteorological Register may he obtained of 

 E. Stanford, Cockspur Street, London, S.W. Price 2s. 



Fig. 1.— Pediment 

 Barometer. 



barometer, which, by means of the button re- 

 ferred to, can be made to slide up and down the 

 face of the scale. The object of the vernier is 

 to enable the observer to read correctly to 

 hundredths of an inch, which it would be im- 

 possible to do with the unaided eye. Having 

 adjusted the vernier, notice the division on the 

 scale of the instrument next below the bottom 

 of the vernier. Suppose this to be 29*3, or 29 

 inches and 3 tenths. Then look along the 

 vernier until one of its divisions is seen to be 

 in the same line with a division on the scale. 

 Should this be 2, as in fig. 2, then the reading 







III 







' 31 



1 





















1 







2 



3 



4 

 5 

 6 

 7 

 8 

 lHII 9 



















30 













































29 













Fig. 



-Vernier of Barometer. 



will be 29-32 inches, or 29 inches, 3 tenths, and 

 2 hundredths of an inch. 



The barometer, as its name implies, is an 

 instrument for measuring the weight or pressure 

 of the atmosphere. It is popularly known as 

 a "weather-glass", because alterations in the 

 weight of the air are so often accompanied by 

 changes in wind and weather. As indicating 

 coming weather, it is not so much the actual 

 height of the mercury at the time that is to be 

 noted, as the change in level which has taken 

 place since the last observation was made. If 

 the rise be gradual, the fine weather which 

 follows is likely to last longer than if it be a 

 sudden one. In the same way a gradual fall 

 indicates, as a rule, continued unsettled weather, 

 while a rapid dip shows rough weather of shore 

 duration, making good the lines : 



" Long foretold— long last, 

 Short notice — soon past". 



When the mercury has been unusually low and 

 begins to rise again, there is nearly always a 



