7 o8 



. COS t) COS ." COS ft L{R COS ft -{- ffjl - /.) 



sin fi sin-/; A- . </, ; (3 9I 



// = //] 

 and 



f | A cos,-; -f ,/,. i. A /. cos^^ 

 1 ' "' /,. / 4 "- ,, ''." (401 



A - (in tin ) 



A 



In this ruse llu-n, tin: magnetic effect along the radius vector is equal, and in the reverse direction 

 to the din et eilcet ot the external system, which is a fact well known from tin: theory of electro- 

 magnetic screens. 



154. In accordance with the- above formula', we have calculated the current-field at the earth's 

 surlare lor a system like the previously employed 1' = 20 and // = 400 km. 0.063 '^- 



It appears tnmi the lormuke that liu'c too we may calculate o- functions similar to those in Art. 91, 

 that is to say, functions by the aid of which we can find by .subtraction the various quantities answering 

 to the external current-system with an arbitrary Ju . 



In the tables below, a series of such quantities are given The index o has the same significance 

 as in Art. 91. ] urther the value of the current-function and the current-components are calculated for 

 the. same three values of Jit as before, namely, 75, J 80, and aye>. 



On the charts (lii^s. 277 282!, the current-lines are drawn for equidistant values of ip answering 

 to the two extreme cases in these systems. 



1' or the magnetic effect (if the earth-currents, the components /'/, and /',, are calculated for 3 lati- 

 tudes, H = 20, 40 and 90 (see Table CXXY). 



TAI'.LK CXIX. 

 Values of ip in the first extreme case. 



-If = 75 C 



i8o r 



".315 --0.315 -0.315 -3'5 - o-^i.S, o-3'5 0.315 0.315 -0.315 --'3'5 0-315 -3 ! 5 3'5 - -3'J 



--o.;->8:." -0.28-' - o._8o 0.^77 0.274-0.275 0.278 --0.283 0.288 -0.293 0.297 ~-3 01 -33 -~ -33 



O.O|O 0.013 0.058 O.OQO 0.127 0.162 -0.103 ~ O.2l8 -O.2(O 0257 0.269 0.277 0.282 0.202 



1-0.252 ---0.247 o.:'ii ^ o. i |8 -+0.072 o.ooi 0.065 0.117 1 5^ O.JQO 0.213 0.227 ~- 2 35 ~- 2 3" 



* 0.250 - O.2|t) -4-O.22O ^0.173, 4 O.I I.} -O.O5I O.OO9 - O.O6I O.1O5 0.130 0.165 O.l8l O.190 0.191 

 *O.2OI 4-0.199 -^0.183, -^0.153 ^O.115 -+ O.O7 I ^O.O26 O.O15 0.05: -O.o8l O.1O.) -O.II9 -O.I^7 0.120 



- o.ioo 4o.log ^0.103, -t-o.of)~' ^0.078 -*- o.oo i ^0.042 4 0.1123 -^-0.006 0.009 0.021 i 0.029 ~ -33 ~-33 



