ANIl IIATIO (W TIIKIR ATOMRl WEKillTS. 



39 



The closet is of brick, l."> (lecimetres liigli .•uul 12 decimetres scjiuire inside. At 

 one side are two pairs of diH)rs ; tlic space between tlieni could 1)(> lilled with sacks 

 of uoii-couductino: material if desired, but this has not been found necessary. The 

 wliole inner surface of the- closet is lined with sheet zinc, soldei'ed so as to leave no 

 openings but those which are recj^uired. 



Attached to the stone cover of this closet, directly undci- flic nn(hlle knife edge 

 of tlie ])alance, is the axis of the reversal mechanism, on which rotates an object 

 cai'riei', which is pi'ovided with six arms. All the rest of the mechanism serves to 

 mauipulate this carrier. 



The hooks which are supported on this carrier need to jiass in continuous 

 rotation through, the hooks which are attached to the pans of the balance. The 

 details of these hooks are shown in Figs. 17 and 18 ; one is seen at a. It consists 

 of two hollow cones, about 2.5 centimetres in diameter, joined by a cylinder about 

 1.5 centimetres long. The lower hollow cone has a slot four millimetres wide cut 

 through it perpendicular to the plane of the papei-, and the cylinder is cut away as 

 shown. The lower hook h is a smaller cone, fixed to a short rod, h g, on which is 

 also fixed the larger cone c : d is a hollow cone, borne on the object cai'Her, on 

 wdiich the system h c g is supported when not suspended from the hook a. 



Yw,, i7._(_)ne arm of revolving carrier, raised, honks disengaged. 



If the ol)ject carrier, of which the centre and one arm are shown at <? h h, is 

 I'aised, as in Fi'i-. 17, the hook /' is quite free from </, so that e h may be 

 rotated. If e h is lowered when it is in a proper position, h will engage with a, and 

 <I will descend some 2.5 centimetres, leaving a h c g (piite free. In order that a and 



