86 



nearly Ihe same as the sum of the resistances r' -\- v" in 

 the circuits, consisting of the one or the other apparatus, 

 the galvanometer and the earth-plate. 



f) If the galvanic resistance in a circuit P n — Z n i = r" 

 and in an other Pi— Z n i = r', the resistance r is in the com- 

 posed apparatus Pn-f-Pi — Z n i such that 



r r' 



r / _|_ r // 



or in other words: when two point-apparatus Pi and P n are 

 united by a wire and conducted through the galvanometer 

 to the zinkplate Z nI in the earth, the conducting power of 

 this circuit is equal to the sum of powers in the circuit 

 from Pi to Z n i and from P n to Zni. 



If r' and r" are equal, we will have 



1 , 

 r = — r 



2 



The observations on which are founded the properties 

 of the electrical air-current, cited here below, were made 

 in Sodankylä from November 1883 to 31 August 1884 with 

 a point-apparatus on the hill Kommattivaara 129,7 m. 

 high at a distance of 6 km from the station. 



They comprice: 



a) Observation 3 time dayly 5 h a. m. l h p, m. and 9 h p. m. 



Göttinger meantime, 

 H) d:o every 5 minut during 24 hours the 1 and 



th 15 of every month (but Januar 2), 

 <■) d:o 8 and 22 of every month from 8 h 30 m p. m. 



to 10 h 30 m p. m. each half minut, 

 d) d:o 1 and 15 of every month from 8 h 30 m tolO h 



30 m p. m. each half minut, 

 é) d:o 14 and the last of the month during 1 hour 



beginning from the 14 Januar 1884 at 7 h 



