M. G. Wiedemann on Torsion. 105 



mentioned in § 4, and loaded in all with 8175 grams, was set in 

 torsion-oscillations. The elongation A x and A 50 , of its first and 

 its fiftieth swing in the same direction, amounted, in scale-divi- 

 sions as follows : — 



A 1 520-390=130 500-372=158 

 A 50 516-394=122 525-378=147 



A 2 570-334=236 516-387 =129 

 A 50 559-346=213 512-390-5=121-5 



In order that the influence of the resistance of the air might 

 be estimated, a light pasteboard box closely similar in form to 

 the weights with which the wire was loaded was placed upon 

 them, which at the same time bore a pasteboard ring similar to 

 the brass ring, and some pasteboard appendages copying the 

 eccentric parts of the apparatus. The weight of them was only 

 68 grams ; so that the alteration thereby conditioned could not 

 exert any particular action ; the oscillation-period, too, was 

 not greatly changed ; the resistance of the air, however, was 

 probably about doubled. 



The oscillation-amplitudes A and A 50 were : — 



A 534-372=152 552-350=202 529-376=153 

 A 50 526-379=147 543-362=181 523-382=141 



From this, according to the formula A 50 — A^ 49 , follows 

 the ratio x of two successive elongations (in percentages): — 



Without the pasteboard addition 9995 99'98 99-94 99-97 

 With „ „ 99-82 99-92 99-94 



With the thick wire here employed, the influence of the 

 friction of the air is therefore not considerable. The diminu- 

 tion of the oscillation-amplitude does not amount on the ave- 

 rage to 0*1 per cent., while the shifting of the permanent posi- 

 tion of equilibrium in the same wire from +b to — b with the 

 alteration of the temporary torsion from +a to —a amounts 

 to about 3*8 per cent, of the latter. 



23. Accommodation. — As the same fractional relations that 

 condition the static displacement of the position of equilibrium 

 occur also in a perfectly analogous manner in the oscillations, 

 the analogous general relations must also result in the latter 

 as in the former. 



Just as in alternatingly directed torsions by temporarily 

 acting weights, we observe correspondingly in the oscillations 

 also first a period of accommodation. As during it with the 

 former the permanent position of equilibrium is first much 

 shifted, so at first the elongations of. the swingings diminish 

 greatly. Since in this period the permanent torsions rise very 



