. The London, Edinburgh and Dublin philosophical magazine and journal of science . e one case, oncooling below a certain temperature, there was a sudden yield-ing to the stress, in the other there was a sudden diminutionof permanent strain. A careful consideration of the resultsof my own experiments, and of those of Mr. Gore and Pro-fessor Barrett, satisfied me that in this, as in many otherinstances, temporary stress and permanent strain act in oppo- * This is not so if the wire be heated rather slowly ; but, on the con-trary, in this case there is a very decided permanent untwist (see experi
. The London, Edinburgh and Dublin philosophical magazine and journal of science . e one case, oncooling below a certain temperature, there was a sudden yield-ing to the stress, in the other there was a sudden diminutionof permanent strain. A careful consideration of the resultsof my own experiments, and of those of Mr. Gore and Pro-fessor Barrett, satisfied me that in this, as in many otherinstances, temporary stress and permanent strain act in oppo- * This is not so if the wire be heated rather slowly ; but, on the con-trary, in this case there is a very decided permanent untwist (see experi-ment V.). t Phil. Mag. ser. 4, vol. xlvi. p. 472. Phil. Mag. S. 5. Vol. 24, No. 148. Sept. 1887, S 258 Mr. H. Tomlinson on raising Iron under Temporary site directions as regards their effects on the physical propertiesof matter. I was moreover led to test, not only the effects oftorsional stress and strain, but also those of other mechanicalstresses and strains, for the most part with arrangementswhich will now be described. Fig. 1. Battery of30 Groves cells SIZE Galvanometer. ■• Galvanometer The wire was suspended vertically in the axis of a glasstube, A (fig. 1), being clamped at its upper extremity into a Stress or Permanent Strain to a Bright-red Heat. 259 brass block, B, resting on a wooden support fitting on to thetop of the tube, and provided with a terminal for makingconnexion with one pole of a battery of thirty Groves cells,arranged ten in series and three in parallel arc. The currentfrom the battery passed through a set of resistance-coilsarranged so that the resistance could be altered by smallamounts at a time ; the current was also conducted throughan amperemeter and through the wire, passing in or out ofthe latter through the intermediation of a mercury-cup, lower extremity of the wire was clamped into a secondbrass block, 0, to which was secured a mirror, M, reflectingthe light of a lamp on to a scale placed at a distance of onemetre. This block was
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