of a circuit were taken, still some connections might be hidden,
as in Fig. 5. So for practical work, photographs of circuits
are never used. Radio-Tricians use drawings, but instead of
drawing pictures of the parts used in the circuit, they use
symbols, just as the architect does. Fig. 6 shows the circuit
described in the previous paragraph, as a Radio-Trician would
draw it. This shows every connection clearly and if we
understand every symbol perfectly, a circuit diagram of this sort will
mean more to us than a dozen photographs.
Just a word about these symbols--they are nothing but
actual drawings reduced to the fewest possible lines. In the
early days of Radio, the few Radio-Tricians there were all had
their own systems of symbols for their own use. That was good
enough until it became necessary to work together on common
problems--then they had to decide on a single symbol language
Fig. 6
which all could learn and understand. Now-a-days a certain
symbol represents an aerial, and every Radio-Trician seeing that
symbol immediately becomes conscious of a mental picture of a
real aerial which the symbol represents but does not actually
picture. In the same way a certain symbol represents a ground,
another symbol represents a coil, etc. At the end of this
textbook there is a number of Radio devices, also the accepted
symbols for each. You might call this list the alphabet of the
Radio-Trician's symbol language. It will gradually become just
as familiar to you as the a, b, c's, or English alphabet.
TABLES
From infancy we learned to do things with numbers. First
we added numbers, then we learned how to subtract one number
from another, then we learned more complex calculations,
multiplication and division. Whether we realized it or not, the two
