( ^05 ) 



tliu tirst time results iii une and tlie saiiio plate, in the same 

 uiaguetic field and at the same temperature, for all the phenomena 

 relating to the theory of the conduction of electricity and heat in 

 metals. For a complete theory it would also be necessary to investigate 

 the variation with temperature of the different phenomena; at the 

 same time a question would arise about a possible change of the 

 THOMSON-eftect in the magnetic field. But at this stage I wished to 

 leave variation with temperature out of consideration. It is true, in 

 measurements for which a current of heat is required, different tem- 

 peratures occur, but we will suppose this variation with temperature 

 small enough to be neglected in a preliminary theory of the phe- 

 nomena. So far as we can juilge fiom the results obtained, they are 

 not contradictory to this supposition. 



2. I have succeeded in representing variation of resistance and 

 longitudinal-etfect by means of an empiricil formula of the form 



Co i1/- 

 E= 1) 



i + rii/37^ 



in which E represents the phenomenon observed and jV the magnetic 

 force (in these calculations expressed in the unit 1000 C. G. !S.). 



Together with the quanties observed we also give the values ob- 

 tained by means of this empirical formula. It will be shown that 

 it represents the observations very satisfactorily; applied to those 

 made by others, it offers an easy way of comparing their results 

 with mine. Moreover the formula is of great use in deciding that 

 variation of resistance and longitudinal-effect are proportional for all 

 magnetisations, a result which is very important for the theory of 

 the phenomenon. If for instance, we consider the longitudiual-etfect 

 as a variation of the thermo-electric power, it follows that we might 

 deduce the change of the Thomson- effect in the magnetic field from 

 the variation of the increase of resistance with change of temperature. 



3. Varialion of' (he electric resistance. 



a. Measiireinents. The observations of this variation are made 



1) lu tlie denominator \/ M-, where the root has to be taken with a positive value, 

 was written in view of Goldiiammer's remark (Wied. Ann. 36, p. 824, 18S9) that 

 tlie phenomena which do not change sign on reversing tlie field should be functions 

 of JP. 



