694 



The prti-t of tlie enclosure above the screens E is entirely of brass 

 with the exception of tube A,, which is glass. 



At A^ and at the joint with the upper part of the enclosure 

 above ^3, A^, (the letter is omitted in the figure,) the parts fit each 

 other with friction, which is of great convenience in the building 

 up of the apparatus. 



At the upper end the enclosure A is enlarged to a wide chamber 

 containing the parts which serve to keep the carrier afloat. It is 

 closed by an arched cover A^^, which again fits on the w^all with 

 friction. To this part of the enclosure is attached the german silver 

 tube B^B^ which narrows down towards the bottom and to which 

 is fastened at B^ the spring which guides the movable carrier in a 

 vertical direction and the two stopping pins B^, which prevent the 

 carrier from moving too far up or down. ') 



The enclosure further serves to suspend the entire apparatus from 

 two hoi'izontal beams; by means of the ball socket C\6\ the direc- 

 tion of the axis of the apparatus may be changed, without altering 

 its height. The plate C, bears with three adjusting screws (7, on 

 the ground plate 6\, which in its turn is fixed to the beams, and 

 may be shifted in a horizontal plane in two directions at right 

 angles to each other by means of the screws Cj. With the adjusting 

 screws the apparatus may be moved 8 cms up or down; this is 

 necessary in using Faraday's method in order to find the maximum 

 force by displacing the apparatus with respect to the electromagnet. 



b. The movable carrier with adjuncts. In the figure the carrier 

 is indicated by M. It consists of a long thinwalled tube of brass, 

 at the same time light and firm, lengthened by a narrow german 

 silver tube which at its end carries a thread JJ^. The experimental 

 objects are also fitted with german silver top-pieces, which may be 

 screwed on to M^. They are thus easily attached to and detached 

 from the carrier. At convenient heights the brass tube is provided 

 with the following parts : the springs R^ and R^ which guide the 

 rnotion, the marks M^ for the purpose of reading the position of 

 the carrier, a stopping ring 63 for confining the motion between 

 the pins, the electromagnetic coil M^ moving with the carrier, the 

 carriers F^ of the floats and a scale M^. As regards these various 

 parts the following may be added. 



1) The german silver tube might without disadvantage have been replaced by 

 a simpler arrangement ; in the design experiments were contemplated which were 

 not carried out. If due care is taken, the stopping pins may also be dispensed 

 with. 



