Airi". 9— K. HONDA AND S. SHIMIZU: CHANGE IN LENGTH 



was from time to time compared with a deciampere balance. The 

 wire to be tested was soldered into well annealed coj)per wires of 

 about the same diameter, as shown in the annexed cut. It was 

 hun"' vertically in the axial line of the maw-netizinfj* 

 coil so as to lie nearly in the uniform field. The pan 

 attached to the lower end of the wire carried on its 

 under face a few pieces of cotton which softly touched 

 a piece of wood for the purpose of damping without pro- 

 ducing sensible pressure. The lens had a focal length of 

 G6.95 cm., and the number of divisions of the micrometer 

 ocular was 100 to 1 cm. The form of the rotating cylinder 

 is drawn in actual size in the annexed figure. It was 

 made of steel ; the thickness of the cylinder, on which the 

 thin vertical wire came in contact, was 2.85 and 1.51 mm. 

 for nickel and other metals respectively. The front view 

 of the brass socket for holding the steel cylinder is shown 

 in the same figure. The stand on which it was fixed, 



could be made to move 



<: 



> 



up and down as well as 

 forward and backward 

 by means of screw 

 adjustment. By this 

 arr.angement, the cy- 

 linder could be made to 



touch the vertically suspended wire with suitable pressure, and a small 

 rotation of the mirror be given at our disposal. The arrangement is 

 omitted in the first figure. 



The sensibility of the apparatus can easily be changed by simply 

 altering the thickness of the rotating cylinder. In the present 

 experiment, it was such that one division of the micrometer ocular 



