180 DR. S. W. J. SMITH AND ME. J. GUILD: A THEE MOM AGNETIC STUDY OF 



heating and cooling curves very nearly coincide above 700 C. The slight difference 

 (exhibited in fig. 1 which contains the cooling curve above 730 C. for the iron as well 

 as its heating curve) is no doubt due partly to a slight excess of the temperature of the 

 thermocouple during cooling and to a slight defect during heating not amounting to 



660 



680 



700' 



720 740 



Temperature. 



760 



780 



800C 



more than 1 C. in either case compared with that of the specimen. The tempera- 

 ture was not altered quite as slowly in this case as in the others ; but the observations 

 serve to indicate the magnitude of the error which may arise owing to a temperature 

 gradient between the thermocouple and the specimen. 



