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fied, that in copper, iron, and tin, simple traction, leaving permanent 

 elongation, leaves also a thermo-electric effect, the same as Magnus 

 had found by wire-drawing, which is a composite application of lon- 

 gitudinal traction and lateral compression ; and that in a variety of 

 metals, namely, iron, copper, brass, tin, platinum, permanent lateral 

 compression (by hammering) leaves still the same thermo-electric 

 effect, as Magnus had found by wire-drawing. In cadmium, not 

 examined by Magnus, and lead, which had not a given result, the 

 experiments now adduced show a thermo-electric effect of hammering, 

 the same as in all the other metals except iron. Zinc wire was also 

 tested, and found to exhibit the same effect as copper, though 

 Magnus had found a reverse quality as due to wire-drawing. The 

 discrepance in this case is probably due to the peculiar effect of 

 annealing on zinc wire, making it brittle and crystalline, which might 

 give a different condition, as the "annealed" in Magnus's experi- 

 ment, and the "unhammered" in the experiment now adduced. 

 Setting aside this case, the author concludes that generally the effect 

 of permanent lateral compression is the same as that of permanent 

 longitudinal extension, or of hardening by wire-drawing, upon the 

 thermo-electric quality of a wire placed longitudinally in an electric 

 circuit; that in iron it is a deviation from the constrained metal 

 towards bismuth, and that in all the other metals mentioned it is a 

 deviation towards antimony ; and that in copper and iron it is the 

 reverse of the effect experienced by the same metal while under the 

 stress that caused the strain. Since no kind of strain, except uni- 

 form condensation or dilatation in all directions, is free from the 

 directional attribute, it appeared probable to the author that the 

 thermo-electric effects remaining in a metal left with a longitudinal 

 strain, retained after the stress that caused it is removed, must be 

 different in different directions. He therefore experimented on iron 

 hardened by longitudinal compression, and found that it deviates 

 from soft iron towards antimony, or in the contrary way to iron 

 hardened by longitudinal traction. From this, and from the results 

 quoted above, it follows that in iron hardened by compression in one 

 direction, the thermo-electric qualities in this direction differ from 

 those in lines perpendicular to it, as antimony differs from bismuth ; 

 that the reverse statement applies to iron hardened by traction in. one 

 direction ; and that these differing thermo-electric qualities have in 



