•( 774 ) 



Batavia. 



Out of the (liiigi'aiiib ulitaincd in the period 1882 J899, I mea^^urcd 

 for 131 eases tlie amount and the duration of the initial movements 

 of the three components (Hoiizontal Intensity = //, Declination = I), 

 Vertical Intensity = Z. 



Direction- of the initial movement. 



A H was without exception positive. 



A D was with a few exceptions West ; but 12 \ of the number 



of cases was introduced by a slight Easterly movement. 

 A .Z was negatixe; but in 6^ „ of the nuud>er the movement was 



introduced by a slight positive movement. 



Duration. 



Here I have not taken into consideration the duration of the slight 

 introductory movement. 



124 cases furnished : 



A //= 4.5 min. A /) = 3.2 min. A Z= 12.0 min. 



The duration of the Z movement is in general diflicult to deter- 

 mine, as the decrease of the vertical force keeps on mostly much 

 longer. 



It is important to notice that the initial movement of D stops or 

 is inverted, whilst of H the increasing movement keeps on. 



Amount. 



The average amplitude of the movement, arranged according to 

 the ditferenr parts of the day in which it took place, expressed in 



O.OOUOl C. (i. S. (rrz y) : 



h A// 



0—6 a.m. + 45 



6—12 „ +41 



0— 6 p.m. -f52 



6—12 „ +40 



Of a characteristic inequality of the vector during the day little 

 is noticeable. The amount A H arranged according to the duration 

 of tlie movement is : 



Duration A H Number of cases 



— 2 min. 53 y 15 



2— 4 „ 43 45 



4— 6 „ 42 35 



6— 8 „ 33 20 



8- 15 ., 46 6 



