42 M. G. Kirchhoff on the Relation of the Lateral Contraction 



I now pass on to a statement of the numerical results which the 

 observations and measurements have given. 



As far as the scale is concerned, the parts of each axis were 

 not found exactly equal, yet the differences which they exhibited 

 were so small that they may be here neglected. The differences 

 of the mean value of one part of the f axis, and of the mean 

 value of a part of the tj axis, w r ere, however, more considerable. 

 From the measurements made the former is 1*7993 millim., the 

 latter 1-8086 millim. 



An approximate value for C is 2357 millims. In the experi- 

 ments the particulars of which I here communicate, we had in 

 millimetres, 



a'=-24-l, £'=-147-0, g" = 329-6, &"=- 152-3, 



a'" = 147-5, #"=-1512, 2/= 108-85. 



"With a steel rod of about the dimensions given at the com- 

 mencement, which I will indicate by No. 1, 



5=145-04 millims.; 

 and in the first adjustment, 



X'= 143-2, I 7 = 93-3, X" = 12-4, Y"=98-0, 

 Z'=2355-2 millims., Z" = 2355-5 millims., 

 r'-£'=-21, r"-Z/'=-20, 

 f'- fl ' = 35, f'-a"=-29. 

 Using weights of 100 gr., the following readings were ob- 

 tained : — 



Y'. 

 88'2 

 122-9 

 88-1 

 53-0 

 88-5 

 122-8 

 88-0 

 52-8 

 88-2 



The readings were made first without the weights, then after 

 these had been suspended at D' and D n (fig. 1), then after 

 removing them, then when they acted at B' and B", then again 

 after their removal, then after they had been again placed at D' 

 and D", and so on. I have observed the rod several times under 

 similar conditions, first, in order to obtain greater accuracy 

 than one observation would afford; and secondly, in order to 

 notice whether if, after the weights had been removed, a per- 

 ceptible part of the flexion or torsion produced by them remained. 





X'. 



. , 



, . 137-2 



100 . , 



. . 101-2 



. , 



. . 137-0 



100 . , 



. . 101-8 



. . 



, . 137-2 



100 . . 



, . 101-2 



. . 



. 137-1 



100 . . 



. 101-4 



. . 



. 137-0 



X". 



Y". 



25-8 



92-5 



63-0 



56-4 



25-6 



92-4 



61-8 



127-3 



25-7 



92-8 



62-9 



56-4 



25-6 



92-3 



61-4 



127-1 



25-5 



92-6 



