﻿Energy of the Amperian Molecule. 



479 



thereby. The pile and test-piece were therefore together 

 embedded in a slab of paraffin wax, 2*55 centim. thick, 

 through which passed two brass pins 2*65 centim. long and 

 0*3 centim. in diameter, which were melted into the wax on 

 either side of the test-piece, and served to prevent any relative 

 motion between it and the pole-pieces. 



On trying this soon after the paraffin had set, the following 

 readings were obtained in the right* direction ; that is to say, 

 they pointed to a cooling of the iron when the field was 

 strengthened. 



t= 



15 



30 



45 



60 



30 



60 sees 



00 +0-31 +083 +1-29 +1-26 +126 +135 +137 



Here t stands for the time in seconds after altering the 

 field between the values 3310 and 3090 either way (H = 220). 



The readings (which correspond to the { final mean differ- 

 ences " of Table I.) : are plottedjn curve (a). Curve (h) in 



* The + sign is used in what follows to indicate that the readings 

 are in accordance with theory, and vice versa. 



