the use of coils. Or seeing the symbol will do the same thing
and later, just the capital letter "L" which represents the
electrical properties of an inductance coil in use.
Of course, a coil, a vacuum tube, or an aerial does not work
alone--any more than a door, a window, or a fireplace has any
practical value alone. The assembled job is what counts, for it
is the complete house--the complete Radio receiver--that the
paying public is interested in. So, just as the architect combines
doors, windows, walls, ceilings, etc., to make a house, so, too, in
a simple receiver, we combine an aerial, a ground, a coil, a
tuning condenser, a detector and earphones.
How shall we describe the connections or the arrangement
of the parts? We might use words: Connect the lead-in from
Fig. 5
the aerial to a tap at the lower end of the coil. Connect the
lower terminal of the coil to a water pipe as a ground. The
fixed plates of the condenser are connected to the upper end of
the coil while the rotating plates are connected to the opposite
end of the coil which is already connected to the gr6und. Place
the phones in series with the detector and then connect the free
ends to the terminals of the variable condenser. All this is
rather difficult to grasp, no matter how clear or how detailed our
word description is. And surely it isn't convenient if we deal
with any number of different circuits.
You might say, "Why not photograph the circuit?" That
might be all right for some purposes, but the eye of the camera
does not see through obstructions and even though several views
