4 M. G. Wiedemann on Torsion. 



which stretched the wire. Before placing them the wire was 

 annealed under feeble tension. 



3. Repeated Torsion in the same Direction. — First a brass 

 wire of 480 millims. length and 2 millims. thickness, which 

 was loaded beneath with altogether 10460 grams, was re- 

 peatedly twisted by increasing weights Gr, and the first tem- 

 porary torsion T which took place immediately after the initial 

 complete action of the weights was, so far as possible, con- 

 stantly observed (the commencement of which was known by 

 the little rod x striking against the wires w w), as well as the 

 final temporary torsion T 1? which was definitively produced 

 after a long time. Likewise on lifting the torsion-weights 

 the torsion P which at first set in, and the finally constant 

 permanent torsion P 1? were measured. The values of T and 

 P cannot be exactly determined by any method, since the 

 twistings of the wire that take place on lowering and winding 

 up the weights immediately pass over, at the full action and the 

 complete lifting of the weights, into the deformations produced 

 by the aftereffect. 



The results of the observations are contained in the follow- 

 ing Table, in which A denotes the differences between the con- 

 secutive values of T x — P : : — 



I. 



W. 30 40 50 60 70 80 90 100 110 120 130 140 



T 312 416 523 628 733 844 956-5 1070 1191 1338 1510 1725 



T, 312 416 523 628 734 845 959 1074 1204 1351 1543 1820 



P 0-6 1-3 2-3 3-8 5-8 9-8 16 26-3 44 73-3 132-8 253 



I\ 0-6 13 2-3 3-8 58 9'8 16 26-3 43-3 71-8 130 245 



Tj-P, 311-4 414-7 520-7 624-2 7282 835 943 1048-7 1160-7 1279-2 1413 1575 

 A 3.1038 103-3 106 103-5 104 1048 108 105-7 112 118-5 133-8 162 



Thereupon the wire was again twisted sixteen times by 

 the weight 140. Then was 



XVII. 



T. T . P. P . T — P . 



1913 1919 373-8 372 1547' 



If now the same wire was again twisted by increasing 

 weights, its permanent torsion remaining constantly P x = 372 ; 

 then was 



XVIII. 



W. 30 40 50 60 70 80 90 100 110 120 130 140 

 T 372 682 787 892 9995 1107 1217 1329-5 1442 1555 1673 1793 1909 

 Tj 372 682 787 892 1001-5 1109 1219 1332-5 1445 1559 1677 1797 1914 

 T 1 -? 1 310 415 520 6295 7375 847 960 1073 1187 1305 1425 1542 

 A 3.103 105 105 109-5 107-5 110 113 113 114 118 120 119 



