252 



THE WORLD'S ADVANCE 



at random within the box interior, it is 

 suggested that bare wire encased in thin 

 rubber tubing be used, the wires thus in- 

 sulated, being fastened to the box in a 

 pre-arranged manner by means of small 

 escutcheon pins. 



This set will perhaps furnish a little 

 difficulty, as regards facility of opera- 

 tion, when used for the first few times.* 



"No matter what coupling may be used, the 

 set is always tuned to two wave lengths. Pro- 

 vided all other adjustments of the set remain 



"Assume that the original setting is coupling 

 Ki t and condenser capacity Ci (No. I con- 

 denser) the set being tuned at 1200 metres 

 and 200 metres. Then assuming that it is 

 desired to receive from a 1200 metre station, 

 and eliminate one at 200 metres, the process 

 of tuning out is as follows: 



"i. Increase the condenser capacity Ci to a 

 new value Ci, so that the 1200 metre station 

 is lost for a moment, and the 200 metre 

 station has become very faint or is also cut 

 out. 



"2. Loosen the coupling until a point is 

 reached where the 1200 metre station is again 



Wifhwf Telephone Switch 



I f ~^ilamem} Aljdi n 



vvv\ 



dudion wing - 

 fad ~ cc/l switch- 



useoud/on Ikedet 



To rig/i f C i in porg/tel with load coil. JJS-i to left C tin senes with bod coil 

 Intermediate c/rcuif in use ttJ-2 intermediate circuit cut out. 



The /s turns co// on second primary withCz short circuited 



Wiring Diagram for Complete Receiving Set Without the Telephone Switch. 



fixed, increasing the coupling causes an in- heard, but at this new coupling, the 200 metre 

 creasing difference between the two waves ** i pntirplv mt nut * 

 to which the set is tuned, one a long, the 

 other a short wave. 



station is entirely cut out.' 



Arlington may be heard by turning 



*See London Electrician, July 19, 1912, p. 623, and 

 Electrician & Mechanic, September, 1911. 



*Quoted from a lecture by Mr. A. S. Blatterman 

 at the Washington University, 1914, on the Marconi 

 multiple tuner. 



