The Birmingham age-herald., 1922-04-30
VACUUM TUBE IS
 ALADD|N'S LAMP
Its Development Made Radio Telephony PossibIe-HaS
 Great Future Uses

There is no invention the genius of man has produced so important and so far-reaching in it's possibilities as the vacuum tube used in radio com munication It is in every respect the modern Aladdins Lamp, and the genii il will conjure up in the future are unlimited in their number.
 It is only in recent years that the full impertance of this marvellous little instrument has become req lized. and scientists the world over are working feverishly day and nlght to develop the possibilities Tn Whlch the tube can be utilized
 Before describing the steps when led to its invention it might be well to briefly outline some of the impor- tant uses to which 1t is now being put. Ii is the instrument that mas made possible simultaneous multlple& telegraphy and telephony on single wire between two cities, 1t has rev olutionized telephone conversation across the continent, and it has also revolutlonized radio communication
 Win Replace Aiternators
 In the immediate future it will re- place the present cumbersome alter nators as generator of alternating current and it will be used for all kinds of prospecting work in locat- ing metals and valuable minerals. In fact, so far as a generator ot alter mating current is concerned, very rapid strides are being i-.ade in it's development, and have seen vacuum tubes in one of the big commercial laboratories which have an output of ten kilowatts at any frequency de- sired.
 This wonderful little instrument was first conceived more than 30 years ago. when Thomas A. Edison was experimenting with the incan- descent electric bulb. He found at that time that by placing a second electrode into the vacuum tube he had devised that very peculiar | phenomenon occurred when the fila ment was lyhted and another bat tery was joined to the second elec- trode and the filament This became known as the "Edison effect" It was the property of allowing a current only to pass in one direction.
 This discovery lay dormant for sew eral years until wireless telegraphy had been successfully accomplished by Marconi.
 In the early days of radio commit nication practically every scientist was seeking more sensitive detec- tor. One of these Prof J. A. Fleming. scientific advisor to Marconi. devel- oped out of the Edison effect the so- called "Fleming valve which con sisted of an ordinary electric bulb with a plate placed around the fila ment This Instrument immediately increased the range of every wirelesa station several times by It's extreme sensitivity. The manner in which it operated was exactly the same as the crystal detector-that is. in the form of an electric valve. It cut the in- coming alternating radlo currents IT two. permitting only one half 10 pass through the telephone receivers anu completely stopping the passage ol the other half of the current. II was on this device that Professor Elem ing, through the Marcon company obtained basis patent on all vacuum tubes.
 De Forest Discovered Grid
 Shortly after this Dr. Lee De For est. while experimenting with the vacuum tube. placed nttle coll of wire in between the filament and the plate. This little coil became knowA as the grid" and 1t IS this little coll that makes the vacuum tube the won-