But I do not wish to mislead you in any way, and I can speak from personal experience in this case. We do not race off with man's messages in the same sense as these other messengers do. Our swiftness of communication depends upon the simple fact that man provides a whole connecting regiment of us between the two distant places. And when the order to march is given we all move off at practically the same moment. In this way the electrons at the far end of the connecting wire are able to cause signals there immediately. This is the secret of man's success in being able to hold immediate communication with his distant friends. His success is due entirely to the co-operation of us electrons. My personal experience has been in connection with a very simple telegraphic arrangement. Indeed, the most of our duties in transmitting messages are performed with this particular kind of instrument, known as a "Morse sounder." At the time of which I speak, I had become attached to an atom of iron in the end of a long telegraph wire. From this you will probably guess that my experience was gained some time ago, for man does not use iron wires nowadays in fitting up telegraph lines. He used iron at first, and some of these lines still exist, but when he discovered that a very much lighter copper wire would serve the same purpose, he discarded the heavy iron wires. Man explained the matter by saying that the copper offered less resistance to the electric current, and the majority of people were quite satisfied with this kind of explanation. Of course these are merely convenient phrases which give man no real reason for the difference. The real reason is that we electrons are able to move about from one copper atom to another with very much greater ease than we can among the iron atoms. That is the reason why man made the change from iron to copper wires, although he had no idea of the reason at the time. To return to my experience in connection with a telegraph instrument, I found that we were being subjected to a series of forced marches. The whole regiment of electrons along the line made a forward move. The line of march ended in a short length of fine wire wound around a piece of soft iron to form an electro-magnet. The end of the wire dipped into the earth, as I have explained in an earlier chapter. Now all that we electrons had to do was to make a forward move, halt, forward again, another halt, and so on. Sometimes the signal to halt was longer in being given than at other times, but we found that this was intentional, and that there were two definite lengths of march. I have explained already how we marching electrons cause an electro-magnet to attract a piece of iron and let it go again as soon as we cease marching. It only remains for me to give you a general statement of how we work the Morse telegraph.