250 



THE WORLD'S ADVANCE 



JS 



Various Parts of the Mineral Detector. 



and 3/1 6" inside diameter. Into one end 

 solder or "sweat in" a piece of tubing 

 y%" inside diameter. It will probably be 

 necessary to sandpaper the outside of 

 this latter tube to a considerable extent, 

 as the nearest sized tubing manufactured 

 is somewhat larger than 3/16" outside 

 diameter. Drill the standard as indicated 

 for a J4" hole, and after sandpapering 

 the tube, and the standard as well, ready 

 for finishing, drive the tube into posi- 

 tion. Then drill and tap a piece of 3/16" 

 rod for a 4-36 thread, and screw into 

 this a piece of threaded y%" 

 rod, about 2" long. Obtain a 

 spring to fit over the y%" rod 

 and fit the parts together as 

 indicated. Purchase or turn 

 a rubber handle a disc may 

 be used and fasten to the 

 y%" rod by drilling and 

 threading for a 4-36 thread. 

 A forced fit, using a drill 

 slightly smaller than the rod, 

 will frequently give good re- 

 sults. 



It will probably be found 

 easier to purchase the cup 

 and fit it to a 3/16" rod than 

 to turn it up. A piece of 

 3/1 6" rod should be sol- 

 dered, or fastened by thread- 

 ing, to the cup. 



Drill 3/16" holes in the 

 standard bases, and solder 



in 3/1 6" rod, threaded at the other ends 

 for a 10-24 thread. Drill through the 

 lower part of the movable standard, fit- 

 ting the rod to the lower part, the up- 

 per part serving as a socket for the 

 pivot. These standard pieces should be 

 squared up with considerable care, the 

 centers for the holes also being located 

 carefully. 



ADDITIONAL DETAILS : Besides the four 

 handles for the switches, one should be 

 turned up to the size indicated in E, 

 Fig. 6, as a handle for the coupler axis. 



Turn up three rings to the size indi- 

 cated in Fig. I, 2>" O. D. and i^" 

 I. D., and from $/s" to %" thick. The 

 rings should preferably be of black fibre, 

 though stained wood will serve the same 

 purpose. 



In case the telephone key is not used, 

 it will be necessary to use the Type D, 

 a three pole Keystone rubber base 

 switch, as indicated, as well as a double- 

 pole double-throw switch, placed not on 

 the box but conveniently near it. 



ASSEMBLY. 



If the box was not made with the 

 top and sides hinged to the bottom the 

 top being glued to the sides it will be 

 necessary to fasten the interior apparatus 

 to the bottom instead of the top. How- 



I#J 



Details of a Perikon Type Detector. 



