310 W. P. W/tite — Switch for Thermoelement Work. 



auxiliary. The rod, when pushed in, is locked by an iron bar. 

 It first raises the bar, unlocking any other rod that may have 

 been in. Hence, finally, to get a connection for any thermo- 

 element (or other "unknown") along witli its auxiliary, we 

 have only to push the rod for that thermoelement, paying no 

 attention to the auxiliary or to any previously connected ther- 

 moelement ; and the auxiliary can be instantly changed for 

 any thermoelement by rotating the rod between the thumb 

 and finger. 



Detailed Description. 



The base is a shallow wooden box, 5 cm high inside, and with 

 other dimensions as shown in fig. 2. Pins (cut from wire brads 



Fig. 1. 



(o) 



(Ob) 



Fig. 1. Operating rod and its orienting collar. 0'4 full size. 



about 3 mm in diameter) project from it at suitable places to serve 

 for attaching the other parts of the switch. Grooves i-7 cm deep 

 in front and back hold and guide the rod of the lower auxiliary- 

 connecting frame. The floor and sides project 13 cm beyond the 

 back. 



The operating rods (tig. 1) are pieces of 1/2 inch (I2 mm ) birch 

 dowel 18 cm long. The brass sleeve is turned from tubing i-s mm 

 thick, fitting the rod rather closely. It is pinned in place. 

 The coiled spring is for returning the bar when it is unlocked; 

 the pin, P 1} is to hold the spring. The pin, P 2 , is to move one of 

 the two auxiliary connecting frames. The wire collar (shown 

 separate in fig. lb) is to prevent the rod from rotating except 

 when purposely turned by the operator. The rod then turns 

 within the rather tight-fitting collar. The collar can never turn 

 far, since the projecting ends would then strike the flat surface of 

 the lower auxiliary frame. Hence the rod, when turned so as to 

 make its pin engage either auxiliary frame, stays so till pressure 

 enough is applied to turn it within the collar. 



The frame for the operating rods (F, fig. 2) is a rectangular 

 frame made of 4 wooden strips about 20 mm square, with holes 



