803 



upon the experimcnlii! siibslaiu'e in tlic tube, when it is phu'cd in 

 an inhoniogeneons nuignetic tield, was lueasureil in Kameklingii Onnes 

 and Perrier's apparatus by electro- nuignetic compensation. This can 

 be rei)hiced with advantage by a conn pen sat ion by means of weights, an 

 op[)ortunity for wliich is given by the scale Q [)Uiced upon the carrier ^). 

 The hook S serves to move tlie weights on and otf the scale, while 

 the apparatus remains air-tight; it can be moved from the outside, 

 through the opening 0. The rubber tube V is hei-metically attached 

 to the rim of the opening 0, and also to the extremity of the hook ; 

 in this way, the tube and the hook together can be moved sufiiciently ") 

 to be able to lift the weights from the wall table IF and place 

 them on the scale, or vice versa. The glass plate Z enables these 

 manipulations to be watched from the outside. To prevent the rubber 

 tube collapsing when there is a partial vacuum in the apparatus, 

 it is supported on the inside by a flexible spiral of steel wire. We 

 further refer to the ligures, in which the upper portion of the apparatus, 



1) In the apparatus described in Comm. N''. 189» there was also a scale fixed 

 at the top of the carrier; the weights placed upon it did not however serve to 

 measure the force, but only to obtain an approximate equilibrium against the 

 upward pressure of the liquid. (See § Sf' Comm. N'\ 139«). 



~) Compare the similar arrangement for stirring in cryostats, Comm. N . 88 g 4. 



