y . Soc. Edin. Vol. XXXVI 



i Barton on the Temperature Variation of the Permeability of Magnetite. Plate 1. 



Fig. 1. 

 primary and secondary circuits 



Fig. 2. 

 thermo-couple and potentiometer circuits. 



H 



Fig. 5. 



fragment of magnetite. 



MG. 4. 

 ELilON BETWEEN 



AND K 



-J. 



- 



Fig. 3. 

 details of cold junction, 



