622 



Popular Science Monthly 



Tapping Field Telephone Wires with a 

 Pocket Connector 



THE device illustrated is used in field 

 work for tapping telephone wires 

 where it is necessary to make a call on 

 the line at any point. It is made from 

 the body of the arms that form the 

 ordinary machinist's divider. The sharp, 

 tapering points are cut from a 9-in. tool, 

 leaving square stubs 5 in. long. In the 

 ordinary divider the arms are set apart 

 to allow space for the spring. The 

 arms must be bent to take up the space 

 so that their inner surfaces come close 

 together, then holes are drilled with 

 their centers on the parting surfaces so 

 that one-half the hole is in each member. 

 Two of those holes are shown having 

 different sizes to admit wires of different 

 diameters. Small holes are drilled at right 

 angles to these holes to intersect the half- 

 hole in one arm and 

 steel phonograjjh 

 needles are inserted 

 in them. 



Another small hole 

 is drilled through one 

 arm anil intersected 

 at right angles with 

 another, which is 

 tapped to receive a 

 knurled head machine 

 screw. This is used 

 for attaching a con- 

 necting wire to the 

 receiver of the tele- 

 phone. 



In ordinary use the connector is held 

 on the wire by hand, but if connections 

 are wanted for any length of time it is 

 best to retain the wing with its nut and 

 screw. In this case the wing should be 

 cut off, allowing only a ^^-in. stub to 

 project. The device is opened wide 

 enough to clear the stub of the wing to 

 admit the wire, then it is closed and the 

 wing-nut set. The needles should not 

 project too far or they will se\er the wire. 



A new type 

 vacuum tube relay 



A small iH>ckct device for mnkin); conncc- 

 liuns anywhere on a field telephone line 



Strengthening the Static Field 

 of an Amplifier 



THIi so-called audion principle, es- 

 pecially when used in telephone 

 relays, has been applied to \acuum 

 tubes built in a 

 great \'ariety of 

 ways. 



\\'hen the grid, 

 or corresponding 

 electrode through 

 which energy to 

 be amplified is led 

 to the device, is 

 placed close to 

 the filament, the 

 local battery cur- 

 rent is usually 

 controlled most 

 efficiently. The 

 closer t he grid and 

 the filament are lirought together, (he 

 stronger will be the static field between 

 them, and the better the amplification. 

 It is necessary, however, to keep the two 

 out of actual electrical contact. If 

 current could How directly from the grid 

 to (he filament the relay would be 

 partially short-circuited and consequent- 

 ly would not work. 



U. S. patent 1,169,422, issued in I9i(> 

 to A. M. Nicholson, shows the type of 

 vacuum tube relay illustrated. The U- 

 shaped electrode 1 is that through which 

 the incoming feeble cmreiits produce 

 their efTects, and takes tlu' place of the 

 grid in the more usual form <if tube. The 

 lilanient 2 is entwined about the U- 

 ilcclrode I, being wound aclually upon 

 it. The two are kept a])art by the insu- 

 lating effects of a thin la>'er of nickel 

 t).\ide on the forked conductor. The 

 plates 3, 3 are connected with the local 

 ballcry, and the whole relay structure 

 is enclosed in the evacuated bulb 4. 



