312 



Mr. Take Sone on the Magnetic Susceptibilities 



Eigr. 4. 



consisting of two Wollastone wires 0*015 mm. thick, M is a 

 small mirror attached to the lower end of: the bifilar system 

 and facing at right angles to the plane of the figure, and F 

 a copper vane damper dipped in vessel containing a mixture 

 of petroleum and machine oil. I is a rectangular brass 

 pillar with a slide-arm carrying a fixed suspension of the 

 bifilar system. Q is a Quincke microscope with an ocular 

 micrometer whose smallest division corresponds to 1/G0 mm. 

 With the microscope the breadth of the bifilar on its upper 

 end can be observed. S is a trifilar system consisting of 

 two horizontal Y-shaped wooden frames with a small 

 aluminium Y between them, these frames being connected by 

 three fine copper wires, as shown in fig. 4. The aluminium 

 frame can be moved upwards or downwards, 

 so that one can make a minute adjustment 

 of the height of the suspended tube. T is 

 the measuring tube suspended between the 

 pole-pieces of a Weiss electromagnet of inter- 

 mediate size, t is a thermometer placed near 

 the measuring tube to determine the tempe- 

 rature of the specimen under examination. 

 P is a microscope (shown in section) readable 

 to 0*005 mm., with which one can adjust the 

 measuring tube to a correct position. K is a 

 collimator tube of a spectroscope used for the 

 purpose of clamping the arm of the balance 

 by means of its vertical slit. This is necessary 

 when it is required to take the measuring- 

 tube away from the arm, or when the tube is 

 to be adjusted to a correct position by means of the trifilar 

 system without giving the least disturbance to the balance. 

 L is a pan in which a balancing weight is to be placed, 

 and G a metal damper dipped in a vessel of machine oil. 

 W is a glass cup containing water, into which is dipped a 

 fine glass tubing, connected with a fine copper tube U, both 

 being filled with water. 



The whole arrangement was set upon a stone foundation 

 and covered with a case to prevent the disturbances due to 

 air currents. The case has a large glass window, through 

 which we could observe the deflexion of the mirror with a 

 scale and telescope. To make the finer adjustment of the 

 orientation of the mirror from outside, an arrangement shown 

 in fig. 5 was used. 



AB is a kind of reservoir made of glass filled with water 

 and mercury; the left end of this reservoir is connected 

 with the copper tube U described above and the other end 



