128 



Progress of Foreign Science. 



composed a rectangular circuit a b d c (Fig. 4.) One half, 

 a c d was antimony ; the other a b d bismuth. These two halves 

 were soldered together. There were thus two adjacent sides 

 of antimony, and two of bismuth. The length of the greater side 

 was 12 centimetres; that of the other 8. The circuit having been 

 placed horizontally on supports, with two of its sides in the 

 direction of the magnetic meridian, the needle was placed upon 

 one of them. After leaving the apparatus alone, to allow it to 

 assume throughout the equilibrium of temperature, ice was put on 

 one of the two solderings which joined the heterogeneous metals. 

 The needle then showed a deviation of 22° or 23°, the atmospheric 

 temperature being at 14° C. When the temperature of the air 

 was 20°, they observed a deviation of 30 degrees. 



2d Experiment. — Another circuit (Fig. 7.) was formed nearly of 

 the same size, but in which the opposite sides were of the same 

 metal; for example, a b and c d were bismuth, a c and b d an- 

 timony. The apparatus was put in action by placing ice on two 

 opposite angles. This circuit produced a deviation of 30° or 31°, 

 in the same circumstances in which the simple circuit afforded 

 only 22° or 23°. In this circuit the temperature soon comes to 

 an equilibrium, so that the thermo-electric effect appears weaker 

 in it than it would have been, but for this circumstance. 



Jig. 5. 



>\,m 



D C 



3d Experiment. — A circuit A B D C (Fig. 5.) whose contour had 

 double the length of that of the circuit in the first experiment, was 

 brought into action by ice placed on one of its soJderings. The 

 deviation was only from 13° to 15°, under the same conditions, in 

 which the circuit (Fig. 4.) gave 22° to 23°. 



4th Experiment. — Another circuit (Fig. 6.) was formed of the 

 same length with that of the preceding experiment, but four alter- 

 nations were given it, or four thermo-electric elements ab; a de- 

 notes antimony and b bismuth. This circuit was made active by 



