t is shown in Figure 2.2. The loop has a certain resistance, which is a function of its length and the diameter of the wire. The longer we make the loop, the greater the resistance. As the length increases (the resistance increases), the current in the loop decreases. There will be some point where the current (in amperes) is SO low that the buzzer will not work. The maximum loop length can be increased by using wire with a greater diameter. It can be increased still further by using electrical repeaters placed near the maximum length point. Another relay technique involved a human operator. At the far end of the loop an operator copied the message and retransmitted it down the next leg of the circuit. SIGNALS CONVEY INTELLIGENCE Buzzer Figure 2.2 A simple electrical telegraph circuit. 2.3.2.1 Conveying Intelligence over the Electrical Telegraph. This model of a simple telegraph circuit consists of a copper wire loop with a buzzer inserted at the distant end where the wire pair loops around. At the near end, which we may call the transmitting end, there is an electrical switch, which we will call a key. The key consists of two electrical contacts, which, when pressed together, make contact, thereby closing the circuit and permitting current to flow. The key is spring-loaded, which keeps it normally in the open position (no current flow). To convey intelligence, the written word, a code was developed by Morse, consisting of three elements: a dot, where the key was held down for a very short period of time; a dash, where the key was held down for a longer period of time; and a space, where the key was left in the "up" position and no current flowed. By adjusting the period of time spaces, the receiving operator could discern the separation of characters (A, B, C, and separation of words, where the space interval was longer. Table 2.1 shows the land- line and international versions of the Morse code. By land-line, we mean a code used communicate over land by means of wire conductors. The international Morse code was