( 646 ) 



Rv moans of an elements-switch of wliicli the arrangement may be 

 seen without further description from PI. I fig. 7 and PI. II, we 

 can switcli the single elemejits or combinations of them in series or 

 ill opposition and obtain electromotive forces in the i-atios of 

 J, 2, 3, 4, 5, 6, 7 which bv the central commutator of the elements- 

 switch are connected to the gahanometer wires (jr in a positive or 

 negative sense. The elements-switch has been made of galvanoplastic 

 copper (mounted on ebonite) and packed in a case with cottonwool 

 so that there elec(romoti\e forces are excluded. 



The electromotive forces mentioned cover at intervals of about 

 30 (legs moi-e than the whole range of temperatures below 0° C. 

 Tiierefore in the measurement of a temperature we can each time 

 use a verv near combination of standard-thermoelements for comj)arison. 



§ 3. Di'tci'iiiiiKitions of the clcctroniotirc forces of the obscrratloji- 

 f'/('nieiif. Iji Comm. N". 27 the obserxatioji- and the comparison- 

 element were compai-ed bv means of the detlcctions which they 

 l)roduced successi\ely on the same galvanometer. This deflection- 

 method must always be applied whenever the determinations must 

 be made (piickly. For these determinations of the deflection the 

 string-gahajunnetoi' of Kinthox kn ^) Avhich owing to its sensibility 

 and inde[)endence of magnetic disturbances would for the rest be 

 probably also very suitable for thermoelectric determinations, would 

 ha\e the advantage above other galvanometers that the indications 

 are instantaneous. An opportunity to test this instrument has not 

 yet presented itself. 



In determinations, however, where we especially want to observe 

 fluctuations of the electromotive force about an almost constant value 

 a compensation-method offers lai-ge advantages. In order to avail 

 ourselves of the adxantages offered by the circumstance that the 

 electromotive forces to be compared are approximately equal, the 

 switching in opposition of the observation- and the comparison- 

 element was rendered possible in Comm. N". 27, Avhere the batter}^ 

 of the standard-elements of the nearest electromoti\'e force would 

 then be used. To the arrangement of Comm. N°. 27 for measure- 

 ments of deflections an arrangement has l)een added which allows 

 of a determination of the electromotive force of the observation- 

 element at perfect compensation by means of a zero-method. Thus 

 the comparison of the standard-clemejit with the Clakk-ccII of the 

 arrangements of Comm. N". 27 by means of the deflection-method 

 is left out. Ill tills case the element must give a very small but 



1) Proc. 1003-1004 p. 107. 



